package playback

import (
	"fmt"
	"sort"
	"strconv"
	"strings"
	"time"

	"github.com/Silo-Server/silo-server/internal/models"
)

type PlannerSettingsV3 struct {
	TranscodeEnabled bool
	Allow4KTranscode bool
}

const (
	TerminalMessage4KTranscodeDisabledV3 = "A lower-resolution source is required because 4K transcoding is disabled."
	containerMP4V3                       = "mp4"
	mimeVideoMP4V3                       = "video/mp4"
	degradationAudioConvertedV3          = "audio_converted"
	audioLayoutMonoV3                    = "mono"
	audioLayoutStereoV3                  = "stereo"
	audioLayoutSurround51V3              = "5.1"
)

type PlannerInputV3 struct {
	Request         StartRequestV3
	RequestedFile   *models.MediaFile
	EffectiveFile   *models.MediaFile
	AudioTrackIndex int
	Settings        PlannerSettingsV3
	// Registry holds the transformations the local binary can execute.
	// Progressive remux routes always gate on it: they run in this process.
	Registry *TransformationRegistryV3
	// HLSRegistry optionally widens transformation availability for HLS
	// deliveries, which can execute on pooled transcode nodes as well as
	// locally. Nil means HLS routes gate on Registry alone. It is a lazy
	// producer because building the widened registry can touch the network
	// (node capability fetches): the planner only invokes it when a route
	// decision genuinely depends on node capabilities, so direct-play and
	// other source-preserving starts never pay for it. Producers must
	// return a superset of Registry (local ∪ node capabilities) and should
	// memoize; the transport layer re-validates whichever executor is
	// actually selected.
	HLSRegistry func() *TransformationRegistryV3
	// DVRPUStrippable reports whether this particular source survives the
	// Dolby Vision RPU strip. The registries answer whether the executor
	// carries the transformation; this answers whether the file does, which
	// no capability probe can. Nil means "assume it does", preserving the
	// pre-probe behaviour for callers that cannot run one (the shadow
	// planner, tests). Lazy for the same reason as HLSRegistry: it shells out
	// to ffmpeg, so it is consulted only once every cheap eligibility gate
	// has already passed and a strip route is genuinely on the table.
	DVRPUStrippable     func() bool
	Now                 time.Time
	AttemptedKeys       []string
	AdditionalSubtitles []SubtitleInventoryEntryV3
}

// SourceExecutionMetadataV3 is the immutable source probe snapshot used to
// reopen a frozen playback recipe without consuming later catalog drift.
type SourceExecutionMetadataV3 struct {
	VideoCodec          string
	SoftwareVideoDecode bool
	DurationSeconds     float64
}

// dvRPUStrippable resolves the per-source strip verdict, defaulting to true
// when no probe is wired in.
func (input PlannerInputV3) dvRPUStrippable() bool {
	return input.DVRPUStrippable == nil || input.DVRPUStrippable()
}

// hlsRegistry resolves the registry HLS deliveries gate on: the widened
// local∪node registry when provided, otherwise the local one. Callers must
// keep it behind short-circuits so transformation-free routes never force
// the lazy producer to run.
func (input PlannerInputV3) hlsRegistry() *TransformationRegistryV3 {
	if input.HLSRegistry != nil {
		if widened := input.HLSRegistry(); widened != nil {
			return widened
		}
	}
	return input.Registry
}

type PlannerResultV3 struct {
	Plan             *PlanV3
	Terminal         *TerminalV3
	PlayMethod       PlayMethod
	TranscodeAudio   bool
	TargetVideoCodec string
	TargetAudioCodec string
	// TargetAudioChannels caps the transcode's re-encoded channel count;
	// 0 keeps the historical stereo downmix.
	TargetAudioChannels         int
	TargetAudioBitrateKbps      int
	TargetResolution            string
	TargetBitrateKbps           int
	SubtitleTrackIndex          int
	SubtitleTransportTrackIndex int
	SubtitleBurnIn              bool
	SubtitleCodec               string
	// DownloadedSubtitleID comes from the same inventory snapshot used for
	// planning. Freezing must not re-list a mutable ordinal inventory after the
	// route has already been accepted.
	DownloadedSubtitleID int
	// FrozenSourceMetadata is set only when a durable executable recipe is
	// thawed for a seek reanchor. Transport construction must then use this
	// captured source snapshot instead of a freshly probed media row.
	FrozenSourceMetadata *SourceExecutionMetadataV3
}

func PlanPlaybackV3(input PlannerInputV3) PlannerResultV3 {
	if input.RequestedFile == nil {
		return terminalPlannerResultV3("source_unavailable", "The requested media source is unavailable.", false)
	}
	file := input.EffectiveFile
	if file == nil {
		file = input.RequestedFile
	}
	if input.Now.IsZero() {
		input.Now = time.Now()
	}
	source := SourceDescriptorFromFileV3(file, input.AudioTrackIndex)
	// A source without any video track is audio-only (audiobooks, future
	// music): the video, HDR, and subtitle-burn gates below have nothing to
	// gate, and requiring complete video metadata would terminal a perfectly
	// playable file. It gets its own reduced route family instead.
	if file.IsAudioOnly() {
		return planAudioOnlyV3(input, file, source)
	}
	// Subtitle renderability is delivery-specific, so every candidate route is
	// validated against the capabilities of the delivery class that would
	// execute it. The original_http delivery remains the canonical policy for
	// source-preserving routes and for the up-front terminal decision.
	subtitle := ResolveSubtitlePolicyV3(file, input.Request, input.Settings.TranscodeEnabled, DeliveryClassOriginalHTTPV3, input.AdditionalSubtitles)
	if subtitle.Terminal != nil {
		return PlannerResultV3{Terminal: subtitle.Terminal, SubtitleTrackIndex: -1, SubtitleTransportTrackIndex: -1}
	}
	remuxSubtitle := ResolveSubtitlePolicyV3(file, input.Request, input.Settings.TranscodeEnabled, DeliveryClassProgressiveV3, input.AdditionalSubtitles)
	hlsSubtitle := ResolveSubtitlePolicyV3(file, input.Request, input.Settings.TranscodeEnabled, DeliveryClassHLSV3, input.AdditionalSubtitles)
	// A remux route cannot burn subtitles, so it is only viable when its own
	// delivery can present the selected subtitle without one.
	remuxSubtitleOK := remuxSubtitle.Terminal == nil && !remuxSubtitle.RequiresBurn
	hlsRemuxSubtitleOK := hlsSubtitle.Terminal == nil && !hlsSubtitle.RequiresBurn
	quality := ResolveQualityPolicyV3(input.Request, source)
	videoOK, videoEvidenceInsufficient := videoEligibleV3(source, input.Request)
	var high10Quirk *AppliedQuirkV3
	if !videoOK {
		if quirk, ok := high10DecodeOverrideV3(source, input.Request); ok {
			videoOK = true
			high10Quirk = quirk
		}
	}
	rangeOK, videoClaims := outputRangeEligibleV3(source, input.Request)
	audioOK, passthrough, audioClaims := audioEligibilityV3(source, input.Request)
	if !audioOK && source.AudioCodec == "" && (file == nil || len(file.AudioTracks) == 0) {
		// Video-only media has no audio stream to adapt: treating the absence
		// as an unsupported codec would force a pointless AAC conversion — or
		// a terminal when conversion is unavailable — on a playable file. An
		// audio track whose codec merely failed to probe keeps the codec
		// gate: converting unknown audio is safer than copying it.
		audioOK = true
		audioClaims.Reason = "no_audio_track"
	}
	containerOK := containsFoldV3(input.Request.Capabilities.Containers, source.Container)
	hlsDeliveryOK := deliveryAvailableV3(input.Request, DeliveryClassHLSV3)
	// DV strip eligibility is split by executor pool: a progressive remux
	// executes on this process's ffmpeg, while an HLS remux may run on a
	// pooled transcode node advertising the transformation. Node capability
	// only counts when the client can actually run an HLS delivery, and the
	// widened registry is consulted lazily so non-DV sources never touch it.
	dvStripEligibleLocal := canStripDolbyVisionToHDR10V3(source, input.Request, input.Registry)
	dvStripEligible := dvStripEligibleLocal
	if !dvStripEligible && hlsDeliveryOK && source.DynamicRange == DynamicRangeDolbyVisionV3 {
		dvStripEligible = canStripDolbyVisionToHDR10V3(source, input.Request, input.hlsRegistry())
	}
	// A source whose RPU ffmpeg cannot parse must lose the strip here rather
	// than at the transport, so that the plan's HDR10 promise, the durable
	// session's RemuxDVMode and every restart derived from it stay consistent
	// with what the pipeline can actually produce. Ordered last: the probe
	// only runs once an executor has been found for a strip this client wants.
	dvStripUnsupportedBySource := false
	if dvStripEligible && !input.dvRPUStrippable() {
		dvStripUnsupportedBySource = true
		dvStripEligible = false
		dvStripEligibleLocal = false
	}
	clientDV81Eligible := canClientTransformDV7ToDV81V3(source, input.Request)
	clientHDR10Eligible := canClientTransformDV7ToHDR10V3(source, input.Request)
	// With the server strip gone, a client that cannot take the source range
	// and cannot run its own DV transformation has no route left: this
	// codebase has no tone-map recipe, so every remaining branch funnels into
	// planVideoTranscodeV3's hdr_transcode_unsupported. Terminate here instead
	// so the client is told the actual cause — a source whose Dolby Vision
	// metadata cannot be removed — rather than a generic HDR message that
	// sends the user looking for a missing encoder.
	if dvStripUnsupportedBySource && !rangeOK && !clientDV81Eligible && !clientHDR10Eligible {
		return terminalPlannerResultV3(TerminalDVConversionUnsupportedV3,
			"This source's Dolby Vision metadata cannot be removed cleanly, and this device cannot play the source as it is.", false)
	}

	base := PlanV3{
		ProtocolVersion:        ProtocolV3,
		ExpiresAt:              NewPlanExpiryV3(input.Now),
		SelectedTracks:         selectedTracksForPlanV3(file, input.AudioTrackIndex, subtitle),
		EffectiveRecipe:        recipeFromSourceV3(source),
		Claims:                 ValidationClaimsV3{Video: videoClaims, Audio: audioClaims, Subtitles: subtitle.Claims},
		Subtitle:               subtitle.Decision,
		Transformations:        []TransformationV3{},
		AppliedQuirks:          []AppliedQuirkV3{},
		RuntimeCorrections:     []string{},
		DegradationWarnings:    []DegradationWarningV3{},
		RequestedMediaFileID:   input.RequestedFile.ID,
		EffectiveMediaFileID:   file.ID,
		Source:                 source,
		SubtitleFidelityPolicy: subtitlePolicyNameV3(input.Request.SubtitleFidelityPreference),
		Timeline:               TimelineV3{SourceStartSeconds: floatOrZeroV3(input.Request.StartPosition), PlayerStartSeconds: floatOrZeroV3(input.Request.StartPosition), CanSeekAnywhere: true, SeekRestoration: "player_position"},
	}
	base.AvailableQualities = availableQualitiesV3(input, source)
	base.Subtitle.Inventory = BuildSubtitleInventoryV3(file, input.AdditionalSubtitles)
	base.Claims.Audio.Passthrough = passthrough
	if source.DynamicRange == "hdr_unknown" && rangeOK {
		base.DegradationWarnings = append(base.DegradationWarnings, DegradationWarningV3{
			Code:    "hdr_range_assumed_hdr10",
			Message: "The source is flagged HDR without precise range metadata and is delivered as HDR10.",
		})
	}
	if dvStripUnsupportedBySource {
		// Say why the HDR10 route this client is capable of was not taken;
		// otherwise the fallback looks like an unexplained quality drop.
		base.DegradationWarnings = append(base.DegradationWarnings, DegradationWarningV3{
			Code:    "dolby_vision_strip_unsupported_by_source",
			Message: "This source's Dolby Vision metadata cannot be removed cleanly, so the validated HDR10 route is unavailable for it.",
		})
	}
	if !routeVideoMetadataCompleteV3(source) {
		return terminalPlannerResultV3("source_metadata_incomplete", "The source is missing video metadata required for a validated playback route.", true)
	}
	if !videoOK && videoEvidenceInsufficient {
		// The client's flat codec lists claim this stream, but its evidence
		// tier could not validate it for a direct route. Distinguish that from
		// a device that genuinely cannot play the stream so lower-tier clients
		// see an actionable degradation instead of a mystery transcode.
		base.DegradationWarnings = append(base.DegradationWarnings, DegradationWarningV3{
			Code:    EvidenceInsufficientForDirectV3,
			Message: "The client's capability evidence tier cannot validate this stream for a direct route; an adapted route is used instead.",
		})
	}

	// Automatic quality reductions (device resolution limit, bandwidth
	// estimate/cap, metered fallback) are best-effort. When the only reason to
	// transcode is such a reduction, a validated source-preserving route
	// exists, and the transcode itself cannot execute (HDR sources have no
	// validated reduced-quality recipe yet, or the client/server lacks the
	// transcode route entirely), deliver the source at original quality with a
	// degradation warning instead of refusing playback. Explicit user-selected
	// rungs keep the existing terminals.
	if quality.RequiresTranscode && !quality.ExplicitRung && !subtitle.RequiresBurn && videoOK &&
		(rangeOK || dvStripEligible || clientDV81Eligible || clientHDR10Eligible) &&
		!videoTranscodeExecutableV3(input, source) {
		warnings := append(quality.Warnings, DegradationWarningV3{
			Code:    "quality_reduction_unavailable",
			Message: "Reduced-quality transcoding is unavailable for this source; it is delivered at original quality.",
		})
		quality = originalQualityResultV3(source)
		quality.Warnings = warnings
	}
	base.DegradationWarnings = append(base.DegradationWarnings, quality.Warnings...)

	if quality.RequiresTranscode || !videoOK ||
		(!rangeOK && !dvStripEligible && !clientDV81Eligible && !clientHDR10Eligible) ||
		(subtitle.RequiresBurn && !remuxSubtitleOK && !hlsRemuxSubtitleOK) {
		reasonOverride := ""
		if !quality.RequiresTranscode && !videoOK && videoEvidenceInsufficient {
			// The only reason this route adapts is the evidence tier, not a
			// negative device fact; name that in the decision and in any
			// resulting terminal.
			reasonOverride = EvidenceInsufficientForDirectV3
		}
		return planVideoTranscodeV3(input, base, source, quality, hlsSubtitle, reasonOverride)
	}

	// Profile 7 is normalized on the client against the original range-capable
	// source. A decoder profile/max-instance claim alone is not proof of native
	// dual-layer output, so the default Android route mirrors Silo Apple: P8.1
	// base-layer Dolby Vision first, then same-file HDR10.
	if source.DVProfile == 7 && quality.PreservesSource && videoOK && containerOK && audioOK &&
		audioSelectionUsesContainerDefaultV3(file, input.AudioTrackIndex) && !subtitle.RequiresBurn {
		if clientDV81Eligible {
			plan := base
			plan.Delivery = DeliveryOriginalHTTPV3
			plan.Stream = StreamV3{Protocol: StreamHTTPProgressiveV3, Container: source.Container, MIMEType: MimeFromExtension(file.FilePath), Headers: map[string]string{}, HeaderRefresh: HeaderRefreshNoneV3}
			plan.DecisionReason = "client_dv7_to_dv81"
			plan.EffectiveRecipe.DynamicRange = DynamicRangeDolbyVisionV3
			plan.Claims.Video = VideoClaimsV3{DolbyVision: true, DolbyVisionReason: "client_profile7_to_profile81"}
			plan.Transformations = append(plan.Transformations, TransformationV3{
				Name: ClientDV7ToDV81V3, Executor: ExecutorClientV3, RecipeVersion: ClientDVTransformVersionV3,
				ValidatedClaims: []string{"profile7_rpu_converted_to_profile81", "hdr10_base_layer_preserved", "enhancement_layer_discarded"},
			})
			plan.DegradationWarnings = append(plan.DegradationWarnings, DegradationWarningV3{
				Code:    "dolby_vision_enhancement_layer_discarded",
				Message: "Dolby Vision Profile 7 is played as Profile 8.1 base-layer Dolby Vision; enhancement-layer pixel data is discarded.",
			})
			finalizePlanIdentityV3(&plan, input.Request.PlaybackAttemptID, input.Request.ClientPlaybackContext.Output.OutputContextID)
			if deliverySupportsPlanV3(input.Request, DeliveryClassOriginalHTTPV3, plan) && !planAttemptedV3(plan, input.Request.ClientPlaybackContext.Output.OutputContextID, input.AttemptedKeys) {
				return PlannerResultV3{Plan: &plan, PlayMethod: PlayDirect, SubtitleTrackIndex: subtitle.SelectedIndex, SubtitleTransportTrackIndex: subtitle.TransportIndex, SubtitleCodec: subtitle.Codec, DownloadedSubtitleID: subtitle.DownloadedSubtitleID}
			}
		}
		if clientHDR10Eligible {
			plan := base
			plan.Delivery = DeliveryOriginalHTTPV3
			plan.Stream = StreamV3{Protocol: StreamHTTPProgressiveV3, Container: source.Container, MIMEType: MimeFromExtension(file.FilePath), Headers: map[string]string{}, HeaderRefresh: HeaderRefreshNoneV3}
			plan.DecisionReason = "client_dv7_to_hdr10"
			plan.EffectiveRecipe.DynamicRange = DynamicRangeHDR10V3
			plan.Claims.Video = VideoClaimsV3{HDR10: true}
			plan.Transformations = append(plan.Transformations, TransformationV3{
				Name: ClientDV7ToHDR10V3, Executor: ExecutorClientV3, RecipeVersion: ClientDVTransformVersionV3,
				ValidatedClaims: DV7ToHDR10ClaimsV3(),
			})
			plan.DegradationWarnings = append(plan.DegradationWarnings, DegradationWarningV3{
				Code:    "dolby_vision_removed",
				Message: "Dolby Vision Profile 7 is played from the same 4K file as its HDR10 base layer.",
			})
			finalizePlanIdentityV3(&plan, input.Request.PlaybackAttemptID, input.Request.ClientPlaybackContext.Output.OutputContextID)
			if deliverySupportsPlanV3(input.Request, DeliveryClassOriginalHTTPV3, plan) && !planAttemptedV3(plan, input.Request.ClientPlaybackContext.Output.OutputContextID, input.AttemptedKeys) {
				return PlannerResultV3{Plan: &plan, PlayMethod: PlayDirect, SubtitleTrackIndex: subtitle.SelectedIndex, SubtitleTransportTrackIndex: subtitle.TransportIndex, SubtitleCodec: subtitle.Codec, DownloadedSubtitleID: subtitle.DownloadedSubtitleID}
			}
		}
	}

	if source.DVProfile != 7 && deliveryAvailableV3(input.Request, DeliveryClassOriginalHTTPV3) && containerOK && videoOK && rangeOK && audioOK && quality.PreservesSource &&
		audioSelectionUsesContainerDefaultV3(file, input.AudioTrackIndex) && !subtitle.RequiresBurn {
		plan := base
		plan.Delivery = DeliveryOriginalHTTPV3
		plan.Stream = StreamV3{Protocol: StreamHTTPProgressiveV3, Container: source.Container, MIMEType: MimeFromExtension(file.FilePath), Headers: map[string]string{}, HeaderRefresh: HeaderRefreshNoneV3}
		plan.DecisionReason = "validated_original_playback"
		applyCopiedVideoQuirksV3(&plan, source, input.Request, high10Quirk)
		finalizePlanIdentityV3(&plan, input.Request.PlaybackAttemptID, input.Request.ClientPlaybackContext.Output.OutputContextID)
		if deliverySupportsPlanV3(input.Request, DeliveryClassOriginalHTTPV3, plan) && !planAttemptedV3(plan, input.Request.ClientPlaybackContext.Output.OutputContextID, input.AttemptedKeys) {
			return PlannerResultV3{Plan: &plan, PlayMethod: PlayDirect, SubtitleTrackIndex: subtitle.SelectedIndex, SubtitleTransportTrackIndex: subtitle.TransportIndex, SubtitleCodec: subtitle.Codec, DownloadedSubtitleID: subtitle.DownloadedSubtitleID}
		}
	}

	// A progressive remux maps only the base-layer video stream, so dual-layer
	// Profile 7 can never ship as native Dolby Vision here regardless of the
	// client's decoder claims; the validated HDR10 strip is the only eligible
	// P7 remux recipe.
	remuxRangeOK := rangeOK && source.DVProfile != 7
	// A copy-unsafe source (H.264 with conflicting in-band PPS) must not take a
	// video stream-copy route: the avc1/fMP4 segment would desync strict
	// decoders. Skipping the remux branch drops through to the HLS transcode.
	if videoOK && !source.VideoCopyUnsafe && (remuxRangeOK || dvStripEligible) && (remuxSubtitleOK || hlsRemuxSubtitleOK) {
		plan := base
		plan.Delivery = DeliveryRemuxProgressiveV3
		plan.Stream = StreamV3{Protocol: StreamHTTPProgressiveV3, Container: containerMP4V3, MIMEType: mimeVideoMP4V3, Headers: map[string]string{}, HeaderRefresh: HeaderRefreshNoneV3}
		plan.DecisionReason = "container_normalization"
		transcodeAudio := !audioOK
		progressiveAudioChannels := 0
		localAudioConvertOK := input.Registry != nil && input.Registry.Available(TransformationAudioToAACV3)
		if transcodeAudio {
			// The HLS remux branch below can offload the conversion to a
			// pooled node, but only for clients that can run an HLS
			// delivery: a progressive-only client must keep this terminal
			// (its retryable semantics included) rather than fall through
			// to a generic adaptation_unavailable for a route it can never
			// use. Short-circuit order keeps locally-capable planning from
			// consulting node capabilities at all.
			audioConvertOK := localAudioConvertOK ||
				hlsDeliveryOK && input.hlsRegistry().Available(TransformationAudioToAACV3)
			if !audioConvertOK {
				return terminalPlannerResultV3(TerminalAudioConversionUnsupportedV3, "The required validated AAC conversion toolchain is unavailable.", true)
			}
			progressiveAudioChannels = aacOutputChannelsV3(input.Request, DeliveryClassProgressiveV3, source.AudioChannels, false)
			plan.EffectiveRecipe.AudioCodec = "aac"
			plan.EffectiveRecipe.AudioChannels = intPointerV3(progressiveAudioChannels)
			plan.EffectiveRecipe.AudioLayout = audioLayoutForChannelsV3(progressiveAudioChannels)
			plan.Claims.Audio = AudioClaimsV3{Codec: "aac", Reason: "server_audio_adaptation"}
			plan.Transformations = append(plan.Transformations, TransformationV3{Name: TransformationAudioToAACV3, Executor: ExecutorServerV3, RecipeVersion: "1", ValidatedClaims: []string{ClaimAudioDecodeV3}})
			plan.DegradationWarnings = append(plan.DegradationWarnings, DegradationWarningV3{Code: degradationAudioConvertedV3, Message: fmt.Sprintf("The selected audio track is converted to AAC %s.", audioLayoutForChannelsV3(progressiveAudioChannels))})
			plan.DecisionReason = "audio_adaptation"
		}
		dvStrip := dvStripEligible && (source.DVProfile == 7 || !rangeOK)
		if dvStrip {
			plan.Transformations = append(plan.Transformations, TransformationV3{Name: TransformationServerDV7HDR10V3, Executor: ExecutorServerV3, RecipeVersion: "1", ValidatedClaims: DV7ToHDR10ClaimsV3()})
			plan.EffectiveRecipe.DynamicRange = DynamicRangeHDR10V3
			plan.Claims.Video = VideoClaimsV3{HDR10: true}
			plan.DegradationWarnings = append(plan.DegradationWarnings, DegradationWarningV3{Code: "dolby_vision_removed", Message: "Dolby Vision metadata is removed and the validated HDR10 base layer is preserved."})
		}
		if !dvStrip {
			applyCopiedVideoQuirksV3(&plan, source, input.Request, high10Quirk)
		}
		// The progressive remux executes on this process's ffmpeg, so its
		// server transformations must be locally available; when only pooled
		// nodes carry them, the HLS remux below ships the same recipe on a
		// node-offloadable delivery instead.
		progressiveExecutable := (!transcodeAudio || localAudioConvertOK) && (!dvStrip || dvStripEligibleLocal)
		if remuxSubtitleOK && progressiveExecutable {
			applySubtitleDecisionV3(&plan, remuxSubtitle.Decision)
			plan.Claims.Subtitles = remuxSubtitle.Claims
			finalizePlanIdentityV3(&plan, input.Request.PlaybackAttemptID, input.Request.ClientPlaybackContext.Output.OutputContextID)
			if deliverySupportsPlanV3(input.Request, DeliveryClassProgressiveV3, plan) && !planAttemptedV3(plan, input.Request.ClientPlaybackContext.Output.OutputContextID, input.AttemptedKeys) {
				return PlannerResultV3{Plan: &plan, PlayMethod: PlayRemux, TranscodeAudio: transcodeAudio, TargetAudioCodec: plan.EffectiveRecipe.AudioCodec, TargetAudioChannels: progressiveAudioChannels, SubtitleTrackIndex: remuxSubtitle.SelectedIndex, SubtitleTransportTrackIndex: remuxSubtitle.TransportIndex, SubtitleCodec: remuxSubtitle.Codec, DownloadedSubtitleID: remuxSubtitle.DownloadedSubtitleID}
			}
		}
		if deliveryAvailableV3(input.Request, DeliveryClassHLSV3) && hlsRemuxSubtitleOK {
			plan.AppliedQuirks = []AppliedQuirkV3{}
			plan.RuntimeCorrections = []string{}
			plan.Delivery = DeliveryRemuxHLSV3
			plan.Stream = StreamV3{Protocol: StreamHLSV3, Container: "hls", MIMEType: "application/vnd.apple.mpegurl", Headers: map[string]string{}, HeaderRefresh: HeaderRefreshNoneV3}
			hlsTranscodeAudio := transcodeAudio
			hlsAudioChannels := 0
			if hlsTranscodeAudio {
				hlsAudioChannels = aacOutputChannelsV3(input.Request, DeliveryClassHLSV3, source.AudioChannels, false)
				plan.EffectiveRecipe.AudioChannels = intPointerV3(hlsAudioChannels)
				plan.EffectiveRecipe.AudioLayout = audioLayoutForChannelsV3(hlsAudioChannels)
			}
			if audioQuirk, ok := hlsEAC3AudioCorrectionV3(source, input.Request); ok && !hlsTranscodeAudio {
				if !input.hlsRegistry().Available(TransformationAudioToAACV3) {
					return terminalPlannerResultV3(TerminalAudioConversionUnsupportedV3, "The device-specific HLS route requires the validated AAC conversion toolchain.", true)
				}
				hlsTranscodeAudio = true
				hlsAudioChannels = aacOutputChannelsV3(input.Request, DeliveryClassHLSV3, source.AudioChannels, false)
				plan.EffectiveRecipe.AudioCodec = "aac"
				plan.EffectiveRecipe.AudioChannels = intPointerV3(hlsAudioChannels)
				plan.EffectiveRecipe.AudioLayout = audioLayoutForChannelsV3(hlsAudioChannels)
				plan.Claims.Audio = AudioClaimsV3{Codec: "aac", Reason: "device_hls_audio_adaptation"}
				plan.Transformations = append(plan.Transformations, TransformationV3{Name: TransformationAudioToAACV3, Executor: ExecutorServerV3, RecipeVersion: "1", ValidatedClaims: []string{ClaimAudioDecodeV3}})
				plan.DegradationWarnings = append(plan.DegradationWarnings, DegradationWarningV3{Code: degradationAudioConvertedV3, Message: fmt.Sprintf("The selected audio track is converted to AAC %s for this device's HLS route.", audioLayoutForChannelsV3(hlsAudioChannels))})
				appendAppliedQuirkV3(&plan, *audioQuirk, "")
			}
			// DTS and TrueHD are not HLS-native audio codecs. A client's
			// progressive DTS decode claim does not transfer to segmented
			// fMP4/TS: copied DTS in an HLS route drags Media3's audio clock
			// (device stall corrections, ~0.3x pacing, frozen position
			// reports), so the copy is converted to AAC — surround-preserving
			// when the source is multichannel.
			if !hlsTranscodeAudio && !hlsNativeAudioCodecV3(source.AudioCodec) {
				if !input.hlsRegistry().Available(TransformationAudioToAACV3) {
					return terminalPlannerResultV3(TerminalAudioConversionUnsupportedV3, "The HLS route requires the validated AAC conversion toolchain.", true)
				}
				hlsTranscodeAudio = true
				hlsAudioChannels = aacOutputChannelsV3(input.Request, DeliveryClassHLSV3, source.AudioChannels, true)
				plan.EffectiveRecipe.AudioCodec = "aac"
				plan.EffectiveRecipe.AudioChannels = intPointerV3(hlsAudioChannels)
				plan.EffectiveRecipe.AudioLayout = audioLayoutForChannelsV3(hlsAudioChannels)
				plan.Claims.Audio = AudioClaimsV3{Codec: "aac", Reason: "hls_audio_adaptation"}
				plan.Transformations = append(plan.Transformations, TransformationV3{Name: TransformationAudioToAACV3, Executor: ExecutorServerV3, RecipeVersion: "1", ValidatedClaims: []string{ClaimAudioDecodeV3}})
				plan.DegradationWarnings = append(plan.DegradationWarnings, DegradationWarningV3{Code: degradationAudioConvertedV3, Message: "The selected audio track is converted to AAC for HLS delivery."})
			}
			if !dvStrip {
				applyCopiedVideoQuirksV3(&plan, source, input.Request, high10Quirk)
			}
			if hlsTranscodeAudio {
				plan.DecisionReason = "hls_audio_adaptation"
			} else {
				plan.DecisionReason = "hls_packaging_required"
			}
			applySubtitleDecisionV3(&plan, hlsSubtitle.Decision)
			plan.Claims.Subtitles = hlsSubtitle.Claims
			finalizePlanIdentityV3(&plan, input.Request.PlaybackAttemptID, input.Request.ClientPlaybackContext.Output.OutputContextID)
			if deliverySupportsPlanV3(input.Request, DeliveryClassHLSV3, plan) && !planAttemptedV3(plan, input.Request.ClientPlaybackContext.Output.OutputContextID, input.AttemptedKeys) {
				targetAudio := "copy"
				if hlsTranscodeAudio {
					targetAudio = "aac"
				}
				return PlannerResultV3{Plan: &plan, PlayMethod: PlayRemux, TranscodeAudio: hlsTranscodeAudio, TargetVideoCodec: "copy", TargetAudioCodec: targetAudio, TargetAudioChannels: hlsAudioChannels, TargetResolution: resolutionLabelV3(source.Height), TargetBitrateKbps: source.BitrateKbps, SubtitleTrackIndex: hlsSubtitle.SelectedIndex, SubtitleTransportTrackIndex: hlsSubtitle.TransportIndex, SubtitleCodec: hlsSubtitle.Codec, DownloadedSubtitleID: hlsSubtitle.DownloadedSubtitleID}
			}
		}
	}
	if deliveryAvailableV3(input.Request, DeliveryClassHLSV3) {
		return planVideoTranscodeV3(input, base, source, quality, hlsSubtitle, "copy_routes_exhausted")
	}

	return terminalPlannerResultV3("adaptation_unavailable", "No validated playback route is available for this source and output route.", false)
}

// availableQualitiesV3 publishes the server ladder rungs a client could
// request for this source through a quality_change replan. The source rung is
// always present; transcode rungs are listed only below the source's own
// height and only when the cheap transcode gates pass. Registry availability
// is deliberately not consulted: it can trigger lazy node-capability fetches,
// which source-preserving starts must never pay for, and a rung whose
// toolchain is missing degrades to a retryable terminal at replan time.
func availableQualitiesV3(input PlannerInputV3, source SourceDescriptorV3) []AvailableQualityV3 {
	qualities := []AvailableQualityV3{{
		Label:           QualityOriginalV3,
		Height:          source.Height,
		BitrateKbps:     source.BitrateKbps,
		PreservesSource: true,
	}}
	if source.Height <= 0 {
		// Fixed rungs must sit strictly below a known source height; unknown
		// probe metadata cannot prove that any advertised rung avoids upscaling.
		return qualities
	}
	if !deliveryAvailableV3(input.Request, DeliveryClassHLSV3) || !input.Settings.TranscodeEnabled {
		return qualities
	}
	if is4KSourceV3(input.EffectiveFile, source) && !input.Settings.Allow4KTranscode {
		return qualities
	}
	if hdrTranscodeUnavailableV3(source) {
		return qualities
	}
	for _, height := range []int{2160, 1080, 720, 480} {
		if height >= source.Height {
			continue
		}
		qualities = append(qualities, AvailableQualityV3{
			Label:       resolutionLabelV3(height),
			Height:      height,
			BitrateKbps: ladderBitrateKbpsV3(height),
		})
	}
	return qualities
}

// audioAvailableQualitiesV3 is the audio-only menu: quality rungs are a video
// concept, so the only entry is the source itself.
func audioAvailableQualitiesV3(source SourceDescriptorV3) []AvailableQualityV3 {
	return []AvailableQualityV3{{Label: QualityOriginalV3, BitrateKbps: source.BitrateKbps, PreservesSource: true}}
}

// decisionReasonBandwidthCapV3 marks a plan whose recipe was constrained by
// the request's bandwidth cap rather than by decode capability.
const decisionReasonBandwidthCapV3 = "quality_bandwidth_cap"

// planAudioOnlyV3 plans sources without a video track (audiobooks, music).
// The route family is deliberately small: the original container over
// progressive HTTP when the client decodes the audio codec, otherwise a
// progressive AAC conversion remux. Video, HDR, quality-ladder, and
// subtitle-burn gates do not apply.
func planAudioOnlyV3(input PlannerInputV3, file *models.MediaFile, source SourceDescriptorV3) PlannerResultV3 {
	request := input.Request
	audioOK, _, audioClaims := audioEligibilityV3(source, request)
	bandwidthCapKbps := optionalValueV3(request.BandwidthCapKbps)
	bandwidthCapExceeded := bandwidthCapKbps > 0 && source.BitrateKbps > bandwidthCapKbps
	if source.AudioCodec == "" {
		// A file with neither a video track nor a probed audio codec has no
		// stream the planner can validate a route for.
		return terminalPlannerResultV3("source_metadata_incomplete", "The source is missing audio metadata required for a validated playback route.", true)
	}
	base := PlanV3{
		ProtocolVersion: ProtocolV3,
		ExpiresAt:       NewPlanExpiryV3(input.Now),
		SelectedTracks:  selectedTracksForPlanV3(file, input.AudioTrackIndex, SubtitlePolicyResultV3{SelectedIndex: -1, TransportIndex: -1}),
		EffectiveRecipe: recipeFromSourceV3(source),
		Claims:          ValidationClaimsV3{Audio: audioClaims},
		// Audio-only routes bypass every subtitle gate, so the inventory is
		// empty rather than a list of tracks no route on this plan can deliver.
		Subtitle:               SubtitleDecisionV3{Mode: SubtitleOffV3, Inventory: []SubtitleInventoryItemV3{}},
		Transformations:        []TransformationV3{},
		AppliedQuirks:          []AppliedQuirkV3{},
		RuntimeCorrections:     []string{},
		AvailableQualities:     audioAvailableQualitiesV3(source),
		DegradationWarnings:    []DegradationWarningV3{},
		RequestedMediaFileID:   input.RequestedFile.ID,
		EffectiveMediaFileID:   file.ID,
		Source:                 source,
		SubtitleFidelityPolicy: subtitlePolicyNameV3(request.SubtitleFidelityPreference),
		Timeline:               TimelineV3{SourceStartSeconds: floatOrZeroV3(request.StartPosition), PlayerStartSeconds: floatOrZeroV3(request.StartPosition), CanSeekAnywhere: true, SeekRestoration: "player_position"},
	}
	containerOK := containsFoldV3(request.Capabilities.Containers, source.Container)
	if audioOK && containerOK && !bandwidthCapExceeded && audioSelectionUsesContainerDefaultV3(file, input.AudioTrackIndex) && deliveryAvailableV3(request, DeliveryClassOriginalHTTPV3) {
		plan := base
		plan.Delivery = DeliveryOriginalHTTPV3
		plan.Stream = StreamV3{Protocol: StreamHTTPProgressiveV3, Container: source.Container, MIMEType: MimeFromExtension(file.FilePath), Headers: map[string]string{}, HeaderRefresh: HeaderRefreshNoneV3}
		plan.DecisionReason = "validated_original_playback"
		finalizePlanIdentityV3(&plan, request.PlaybackAttemptID, request.ClientPlaybackContext.Output.OutputContextID)
		if deliverySupportsPlanV3(request, DeliveryClassOriginalHTTPV3, plan) && !planAttemptedV3(plan, request.ClientPlaybackContext.Output.OutputContextID, input.AttemptedKeys) {
			return PlannerResultV3{Plan: &plan, PlayMethod: PlayDirect, SubtitleTrackIndex: -1, SubtitleTransportTrackIndex: -1}
		}
	}
	if !deliveryAvailableV3(request, DeliveryClassProgressiveV3) {
		return terminalPlannerResultV3("adaptation_unavailable", "No validated playback route is available for this audio source.", false)
	}
	transcodeAudio := !audioOK || bandwidthCapExceeded
	if transcodeAudio && (input.Registry == nil || !input.Registry.Available(TransformationAudioToAACV3)) {
		return terminalPlannerResultV3(TerminalAudioConversionUnsupportedV3, "The required validated AAC conversion toolchain is unavailable.", true)
	}
	plan := base
	plan.Delivery = DeliveryRemuxProgressiveV3
	// The remux muxes an audio-only fMP4, so the plan must promise audio/mp4:
	// a declared-tier client probes the advertised MIME with isTypeSupported
	// before it will attach a source buffer, and "video/mp4" with no video
	// track is exactly the mismatch that makes that probe lie.
	plan.Stream = StreamV3{Protocol: StreamHTTPProgressiveV3, Container: containerMP4V3, MIMEType: AudioOnlyRemuxMIMEV3, Headers: map[string]string{}, HeaderRefresh: HeaderRefreshNoneV3}
	plan.DecisionReason = "container_normalization"
	targetAudioChannels := audioOnlyAACOutputChannelsV3(request, source)
	targetAudioBitrateKbps := 0
	if transcodeAudio {
		targetAudioBitrateKbps = audioOnlyAACBitrateKbpsV3(bandwidthCapKbps)
		applyAudioOnlyAACConversionV3(&plan, targetAudioChannels, targetAudioBitrateKbps, bandwidthCapExceeded)
	} else if !deliverySupportsPlanV3(request, DeliveryClassProgressiveV3, plan) && input.Registry != nil && input.Registry.Available(TransformationAudioToAACV3) {
		converted := plan
		targetAudioBitrateKbps = audioOnlyAACBitrateKbpsV3(bandwidthCapKbps)
		applyAudioOnlyAACConversionV3(&converted, targetAudioChannels, targetAudioBitrateKbps, false)
		if deliverySupportsPlanV3(request, DeliveryClassProgressiveV3, converted) {
			plan = converted
			transcodeAudio = true
		}
	}
	if !deliverySupportsPlanV3(request, DeliveryClassProgressiveV3, plan) {
		return terminalPlannerResultV3("adaptation_unavailable", "The progressive delivery cannot decode the planned audio recipe.", false)
	}
	finalizePlanIdentityV3(&plan, request.PlaybackAttemptID, request.ClientPlaybackContext.Output.OutputContextID)
	if planAttemptedV3(plan, request.ClientPlaybackContext.Output.OutputContextID, input.AttemptedKeys) {
		return terminalPlannerResultV3("adaptation_exhausted", "All compatible playback recipes have already failed for this output route.", false)
	}
	if !transcodeAudio {
		targetAudioChannels = 0
		targetAudioBitrateKbps = 0
	}
	return PlannerResultV3{Plan: &plan, PlayMethod: PlayRemux, TranscodeAudio: transcodeAudio, TargetAudioCodec: plan.EffectiveRecipe.AudioCodec, TargetAudioChannels: targetAudioChannels, TargetAudioBitrateKbps: targetAudioBitrateKbps, SubtitleTrackIndex: -1, SubtitleTransportTrackIndex: -1}
}

func audioOnlyAACOutputChannelsV3(request StartRequestV3, source SourceDescriptorV3) int {
	return aacOutputChannelsV3(request, DeliveryClassProgressiveV3, source.AudioChannels, false)
}

// aacOutputChannelsV3 picks an encoder-supported AAC layout that does not
// exceed the active delivery's ceiling. FFmpeg's planned AAC recipes support
// mono, stereo, and 5.1; an intermediate ceiling therefore falls back from
// 5.1 to stereo rather than advertising an output the encoder never creates.
func aacOutputChannelsV3(request StartRequestV3, deliveryClass string, sourceChannels int, preserveSurround bool) int {
	channels := 2
	if sourceChannels == 1 {
		channels = 1
	} else if preserveSurround && sourceChannels >= 6 {
		channels = 6
	}
	capability, ok := request.ClientPlaybackContext.Deliveries[deliveryClass]
	if !ok || capability.MaxChannels == nil || *capability.MaxChannels <= 0 || channels <= *capability.MaxChannels {
		return channels
	}
	if *capability.MaxChannels == 1 {
		return 1
	}
	return 2
}

func audioLayoutForChannelsV3(channels int) string {
	switch channels {
	case 1:
		return audioLayoutMonoV3
	case 6:
		return audioLayoutSurround51V3
	default:
		return audioLayoutStereoV3
	}
}

func audioOnlyAACBitrateKbpsV3(bandwidthCapKbps int) int {
	const defaultAACBitrateKbps = 192
	if bandwidthCapKbps > 0 && bandwidthCapKbps < defaultAACBitrateKbps {
		return bandwidthCapKbps
	}
	return defaultAACBitrateKbps
}

func applyAudioOnlyAACConversionV3(plan *PlanV3, targetChannels, targetBitrateKbps int, bandwidthCapExceeded bool) {
	layout := audioLayoutStereoV3
	warning := "The selected audio track is converted to AAC stereo."
	if targetChannels == 1 {
		layout = audioLayoutMonoV3
		warning = "The selected audio track is converted to AAC mono."
	}
	plan.EffectiveRecipe.AudioCodec = "aac"
	plan.EffectiveRecipe.AudioChannels = intPointerV3(targetChannels)
	plan.EffectiveRecipe.AudioLayout = layout
	plan.EffectiveRecipe.BitrateKbps = intPointerV3(targetBitrateKbps)
	plan.Claims.Audio = AudioClaimsV3{Codec: "aac", Reason: "server_audio_adaptation"}
	plan.Transformations = append(plan.Transformations, TransformationV3{Name: TransformationAudioToAACV3, Executor: ExecutorServerV3, RecipeVersion: "1", ValidatedClaims: []string{ClaimAudioDecodeV3}})
	plan.DegradationWarnings = append(plan.DegradationWarnings, DegradationWarningV3{Code: degradationAudioConvertedV3, Message: warning})
	plan.DecisionReason = "audio_adaptation"
	if bandwidthCapExceeded {
		plan.DegradationWarnings = append(plan.DegradationWarnings, DegradationWarningV3{Code: "bandwidth_cap_applied", Message: "Delivery quality is limited by the configured bandwidth cap."})
		plan.DecisionReason = decisionReasonBandwidthCapV3
	}
}

// planVideoTranscodeV3 always executes on the HLS delivery, so the caller must
// pass the subtitle policy resolved against DeliveryClassHLSV3.
func planVideoTranscodeV3(input PlannerInputV3, base PlanV3, source SourceDescriptorV3, quality QualityResultV3, subtitle SubtitlePolicyResultV3, reasonOverride string) PlannerResultV3 {
	if !deliveryAvailableV3(input.Request, DeliveryClassHLSV3) {
		return terminalPlannerResultV3("client_hls_unsupported", "The client cannot execute the required HLS adaptation route.", false)
	}
	if subtitle.Terminal != nil {
		return PlannerResultV3{Terminal: subtitle.Terminal, SubtitleTrackIndex: -1, SubtitleTransportTrackIndex: -1}
	}
	if !input.Settings.TranscodeEnabled {
		reason := "transcoding_disabled"
		if subtitle.RequiresBurn {
			reason = "subtitle_conversion_unsupported"
		}
		return terminalPlannerResultV3(reason, "The source requires video adaptation, but transcoding is unavailable.", false)
	}
	if is4KSourceV3(input.EffectiveFile, source) && !input.Settings.Allow4KTranscode {
		return terminalPlannerResultV3("no_alternate_version", TerminalMessage4KTranscodeDisabledV3, false)
	}
	if hdrTranscodeUnavailableV3(source) {
		return terminalPlannerResultV3("hdr_transcode_unsupported", "This HDR source requires video encoding, but no validated HDR-preserving or tone-map recipe is installed.", false)
	}
	if !input.hlsRegistry().Available(TransformationVideoToH264V3) || !input.hlsRegistry().Available(TransformationAudioToAACV3) {
		return terminalPlannerResultV3("conversion_tool_unavailable", "The required validated H.264/AAC conversion toolchain is unavailable.", true)
	}
	plan := base
	plan.Delivery = DeliveryTranscodeHLSV3
	plan.Stream = StreamV3{Protocol: StreamHLSV3, Container: "hls", MIMEType: "application/vnd.apple.mpegurl", Headers: map[string]string{}, HeaderRefresh: HeaderRefreshNoneV3}
	plan.EffectiveRecipe.VideoCodec = "h264"
	plan.EffectiveRecipe.AudioCodec = "aac"
	plan.EffectiveRecipe.Width = intPointerV3(quality.Width)
	plan.EffectiveRecipe.Height = intPointerV3(quality.Height)
	plan.EffectiveRecipe.BitrateKbps = intPointerV3(quality.BitrateKbps)
	// Surround sources keep 5.1 through the AAC re-encode (universal Media3
	// decode); only stereo/mono sources — and unknown layouts — downmix to 2.0.
	targetAudioChannels := aacOutputChannelsV3(input.Request, DeliveryClassHLSV3, source.AudioChannels, true)
	audioLayout := audioLayoutForChannelsV3(targetAudioChannels)
	plan.EffectiveRecipe.AudioChannels = intPointerV3(targetAudioChannels)
	plan.EffectiveRecipe.AudioLayout = audioLayout
	plan.Transformations = append(plan.Transformations,
		TransformationV3{Name: TransformationVideoToH264V3, Executor: ExecutorServerV3, RecipeVersion: TransformationVideoToH264RecipeVersionV3, ValidatedClaims: []string{ClaimH264DecodeV3}},
		TransformationV3{Name: TransformationAudioToAACV3, Executor: ExecutorServerV3, RecipeVersion: "1", ValidatedClaims: []string{ClaimAudioDecodeV3}},
	)
	plan.Claims.Audio = AudioClaimsV3{Codec: "aac", Passthrough: false, AtmosPreserved: false, Reason: "server_audio_adaptation"}
	applySubtitleDecisionV3(&plan, subtitle.Decision)
	plan.Claims.Subtitles = subtitle.Claims
	plan.DecisionReason = quality.Reason
	if reasonOverride != "" {
		plan.DecisionReason = reasonOverride
	}
	if subtitle.RequiresBurn {
		plan.DecisionReason = "subtitle_burn_in_required"
		plan.DegradationWarnings = append(plan.DegradationWarnings, DegradationWarningV3{Code: "subtitle_burn_in", Message: "The selected subtitle is rendered into the video."})
	}
	plan.EffectiveRecipe.DynamicRange = DynamicRangeSDRV3
	plan.Claims.Video = VideoClaimsV3{}
	if !deliverySupportsPlanV3(input.Request, DeliveryClassHLSV3, plan) {
		return terminalPlannerResultV3("adaptation_unavailable", "The HLS delivery cannot decode the planned transcode recipe.", false)
	}
	finalizePlanIdentityV3(&plan, input.Request.PlaybackAttemptID, input.Request.ClientPlaybackContext.Output.OutputContextID)
	if planAttemptedV3(plan, input.Request.ClientPlaybackContext.Output.OutputContextID, input.AttemptedKeys) {
		return terminalPlannerResultV3("adaptation_exhausted", "All compatible playback recipes have already failed for this output route.", false)
	}
	return PlannerResultV3{Plan: &plan, PlayMethod: PlayTranscode, TranscodeAudio: true, TargetVideoCodec: "h264", TargetAudioCodec: "aac", TargetAudioChannels: targetAudioChannels, TargetResolution: quality.Label, TargetBitrateKbps: quality.BitrateKbps, SubtitleTrackIndex: subtitle.SelectedIndex, SubtitleTransportTrackIndex: subtitle.TransportIndex, SubtitleBurnIn: subtitle.RequiresBurn, SubtitleCodec: subtitle.Codec, DownloadedSubtitleID: subtitle.DownloadedSubtitleID}
}

// applySubtitleDecisionV3 changes the delivery-specific subtitle policy without
// discarding the source inventory already frozen onto the base plan. Adapted
// routes still address the same combined ordinal space as original_http; only
// the rendering decision and claims vary by delivery capability.
func applySubtitleDecisionV3(plan *PlanV3, decision SubtitleDecisionV3) {
	if plan == nil {
		return
	}
	inventory := plan.Subtitle.Inventory
	plan.Subtitle = decision
	plan.Subtitle.Inventory = inventory
}

func canStripDolbyVisionToHDR10V3(source SourceDescriptorV3, request StartRequestV3, registry *TransformationRegistryV3) bool {
	if source.DynamicRange != DynamicRangeDolbyVisionV3 || !clientSupportsHDR10V3(request) || registry == nil || !registry.Available(TransformationServerDV7HDR10V3) {
		return false
	}
	// Profile 7 always carries an HDR10-viewable base layer. Profile 8 is
	// safe only when the DOVI compatibility id explicitly identifies HDR10.
	return source.DVProfile == 7 || source.DVProfile == 8 && source.DVBLCompatID == 1
}

func canClientTransformDV7ToDV81V3(source SourceDescriptorV3, request StartRequestV3) bool {
	return source.DynamicRange == DynamicRangeDolbyVisionV3 && source.DVProfile == 7 &&
		clientSupportsDVProfileV3(request, 8) &&
		clientTransformationAvailableV3(request, ClientDV7ToDV81V3, ClientDVTransformVersionV3)
}

func canClientTransformDV7ToHDR10V3(source SourceDescriptorV3, request StartRequestV3) bool {
	return source.DynamicRange == DynamicRangeDolbyVisionV3 && source.DVProfile == 7 && clientSupportsHDR10V3(request) &&
		clientTransformationAvailableV3(request, ClientDV7ToHDR10V3, ClientDVTransformVersionV3)
}

func clientSupportsDVProfileV3(request StartRequestV3, profile int) bool {
	hdr := request.ClientPlaybackContext.Output.HDRDetails
	if hdr == nil {
		hdr = request.Capabilities.HDRDetails
	}
	return hdr != nil && containsIntV3(hdr.DolbyVisionProfiles, profile)
}

func clientTransformationAvailableV3(request StartRequestV3, name, version string) bool {
	if !HasFeatureV3(request.ClientFeatures, FeatureClientVideoTransforms) {
		return false
	}
	delivery, ok := request.ClientPlaybackContext.Deliveries[DeliveryClassOriginalHTTPV3]
	if !ok || !delivery.Enabled || !delivery.SupportedOnDevice {
		return false
	}
	for _, transformation := range delivery.Transformations {
		if transformation.Executor == ExecutorClientV3 && transformation.Name == name && transformation.RecipeVersion == version {
			return true
		}
	}
	return false
}

func is4KSourceV3(file *models.MediaFile, source SourceDescriptorV3) bool {
	resolution := ""
	if file != nil {
		resolution = strings.ToLower(strings.TrimSpace(file.Resolution))
	}
	return resolution == "2160p" || resolution == "4k" || resolution == "uhd" || source.Width >= 3840 || source.Height >= 2160
}

type QualityResultV3 struct {
	Label             string
	Width             int
	Height            int
	BitrateKbps       int
	PreservesSource   bool
	RequiresTranscode bool
	// ExplicitRung marks a user-selected fixed rung, as opposed to an
	// automatic reduction from device limits, bandwidth evidence, or caps.
	ExplicitRung bool
	Reason       string
	Warnings     []DegradationWarningV3
}

// ResolveQualityPolicyV3 selects the delivery quality for a plan.
//
// bandwidth_cap_kbps is a hard delivery ceiling and is honored in every
// quality mode: source-preserving delivery is degraded when the source bitrate
// exceeds the cap, fixed rungs are lowered when their ladder bitrate exceeds
// it, and "auto" folds the cap into bandwidth-based rung selection. A metered
// connection with neither a cap nor a bandwidth estimate limits auto
// selection to the conservative 720p rung — the rung auto would pick for a
// mid-range bandwidth estimate — instead of assuming the link can sustain the
// original stream.
func ResolveQualityPolicyV3(request StartRequestV3, source SourceDescriptorV3) QualityResultV3 {
	quality, changed := NormalizeQualityV3(request.QualityPreference)
	var warnings []DegradationWarningV3
	if changed {
		warnings = append(warnings, DegradationWarningV3{Code: "quality_preference_normalized", Message: "Unknown quality preference was normalized to auto."})
	}
	capKbps := optionalValueV3(request.BandwidthCapKbps)
	capExceededBySource := capKbps > 0 && source.BitrateKbps > capKbps
	if quality == QualityOriginalV3 && !capExceededBySource {
		result := originalQualityResultV3(source)
		result.Warnings = warnings
		return result
	}
	targetHeight := source.Height
	reason := "quality_auto_source"
	explicitRung := false
	capApplied := false
	switch {
	case quality == QualityOriginalV3:
		// Only reached when the source bitrate exceeds the cap: the cap is a
		// hard ceiling and outranks the original preference.
		targetHeight = ladderHeightForBandwidthV3(int(float64(capKbps) * 0.8))
		capApplied = true
	case quality != "auto":
		targetHeight, _ = strconv.Atoi(strings.TrimSuffix(quality, "p"))
		reason = "quality_fixed_rung"
		explicitRung = true
	default:
		maxHeight := resolutionHeightV3(request.Capabilities.MaxResolution)
		if maxHeight > 0 && (targetHeight == 0 || maxHeight < targetHeight) {
			targetHeight = maxHeight
			reason = "quality_device_limit"
		}
		bandwidth := optionalValueV3(request.BandwidthEstimateKbps)
		if capKbps > 0 && (bandwidth == 0 || capKbps < bandwidth) {
			bandwidth = capKbps
		}
		if bandwidth > 0 {
			targetHeight = minPositiveV3(targetHeight, ladderHeightForBandwidthV3(int(float64(bandwidth)*0.8)))
			reason = "quality_bandwidth_limit"
		} else if request.Metered {
			if capped := minPositiveV3(targetHeight, 720); capped != targetHeight {
				targetHeight = capped
				reason = "quality_metered_limit"
			}
		}
	}
	if targetHeight <= 0 {
		targetHeight = 1080
	}
	if source.Height > 0 && targetHeight > source.Height {
		targetHeight = source.Height
	}
	// The cap also constrains the rung chosen above: a rung that would
	// preserve the source is forced down when the source bitrate exceeds the
	// cap, and a transcode rung whose ladder bitrate exceeds the cap drops to
	// the cap's rung.
	if capKbps > 0 && !capApplied {
		wouldPreserve := source.Height > 0 && targetHeight >= source.Height
		if (wouldPreserve && capExceededBySource) || (!wouldPreserve && ladderBitrateKbpsV3(targetHeight) > capKbps) {
			capApplied = true
			if capHeight := ladderHeightForBandwidthV3(int(float64(capKbps) * 0.8)); capHeight < targetHeight {
				targetHeight = capHeight
			}
		}
	}
	if capApplied {
		reason = decisionReasonBandwidthCapV3
		warnings = append(warnings, DegradationWarningV3{Code: "bandwidth_cap_applied", Message: "Delivery quality is limited by the configured bandwidth cap."})
	}
	if source.Height > 0 && targetHeight >= source.Height && !capApplied {
		return QualityResultV3{
			Label:           strconv.Itoa(source.Height) + "p",
			Width:           source.Width,
			Height:          source.Height,
			BitrateKbps:     source.BitrateKbps,
			PreservesSource: true,
			ExplicitRung:    explicitRung,
			Reason:          reason,
			Warnings:        warnings,
		}
	}
	label := resolutionLabelV3(targetHeight)
	effectiveHeight := resolutionHeightV3(label)
	if source.Height > 0 && effectiveHeight > source.Height {
		effectiveHeight = source.Height
		label = resolutionLabelV3(effectiveHeight)
	}
	width, bitrate := qualityDimensionsV3(effectiveHeight, source.Width, source.Height)
	if capKbps > 0 && bitrate > capKbps {
		// The ladder has no rung below 480p, so a cap under the lowest rung's
		// bitrate is honored by lowering the encode target directly: the cap
		// is a hard delivery ceiling, never advisory.
		bitrate = capKbps
	}
	result := QualityResultV3{Label: label, Width: width, Height: effectiveHeight, BitrateKbps: bitrate, PreservesSource: !capApplied && source.Height > 0 && effectiveHeight >= source.Height, ExplicitRung: explicitRung, Reason: reason, Warnings: warnings}
	result.RequiresTranscode = !result.PreservesSource
	return result
}

func originalQualityResultV3(source SourceDescriptorV3) QualityResultV3 {
	return QualityResultV3{Label: resolutionLabelV3(source.Height), Width: source.Width, Height: source.Height, BitrateKbps: source.BitrateKbps, PreservesSource: true, Reason: "quality_original"}
}

// hlsNativeAudioCodecV3 reports whether an audio codec can be stream-copied
// into an HLS delivery. The allowlist follows the HLS authoring spec (AAC,
// AC-3, E-AC-3, MP3); everything else — DTS, TrueHD, PCM, Opus — must be
// converted even when the client can decode it in a progressive container.
func hlsNativeAudioCodecV3(codec string) bool {
	switch strings.ToLower(strings.TrimSpace(codec)) {
	case "aac", "ac3", "eac3", "mp3":
		return true
	}
	return false
}

// hdrTranscodeUnavailableV3 mirrors planVideoTranscodeV3's terminal
// condition: no validated HDR-preserving or tone-map transcode recipe exists.
func hdrTranscodeUnavailableV3(source SourceDescriptorV3) bool {
	return source.DynamicRange != "" && source.DynamicRange != DynamicRangeSDRV3
}

// videoTranscodeExecutableV3 mirrors planVideoTranscodeV3's terminal
// preconditions: it reports whether a validated video transcode of this
// source could actually run for this client and configuration.
func videoTranscodeExecutableV3(input PlannerInputV3, source SourceDescriptorV3) bool {
	if !deliveryAvailableV3(input.Request, DeliveryClassHLSV3) || !input.Settings.TranscodeEnabled {
		return false
	}
	if is4KSourceV3(input.EffectiveFile, source) && !input.Settings.Allow4KTranscode {
		return false
	}
	if hdrTranscodeUnavailableV3(source) {
		return false
	}
	return input.hlsRegistry().Available(TransformationVideoToH264V3) && input.hlsRegistry().Available(TransformationAudioToAACV3)
}

func recipeFromSourceV3(source SourceDescriptorV3) EffectiveRecipeV3 {
	return EffectiveRecipeV3{VideoCodec: source.VideoCodec, AudioCodec: source.AudioCodec, Width: intPointerV3(source.Width), Height: intPointerV3(source.Height), FrameRate: floatPointerV3(source.FrameRate), BitrateKbps: intPointerV3(source.BitrateKbps), DynamicRange: source.DynamicRange, AudioChannels: intPointerV3(source.AudioChannels), AudioLayout: source.AudioLayout}
}

func selectedTracksForPlanV3(file *models.MediaFile, audioIndex int, subtitle SubtitlePolicyResultV3) SelectedTracksV3 {
	selected := SelectedTracksV3{}
	if file != nil && audioIndex >= 0 && audioIndex < len(file.AudioTracks) {
		index := audioIndex
		selected.Audio = &TrackIdentityV3{ID: TrackIDV3(file.ID, "audio", audioIndex), Index: &index}
	}
	if file != nil && subtitle.SelectedIndex >= 0 {
		index := subtitle.SelectedIndex
		selected.Subtitle = &TrackIdentityV3{ID: TrackIDV3(file.ID, "subtitle", index), Index: &index}
	}
	return selected
}

// audioSelectionUsesContainerDefaultV3 reports whether an untouched source
// stream can realize the selected audio track. Original HTTP serves the file
// byte-for-byte, so any non-default selection must use a remux/transcode route
// that can map the requested stream explicitly.
func audioSelectionUsesContainerDefaultV3(file *models.MediaFile, audioIndex int) bool {
	if file == nil || len(file.AudioTracks) == 0 {
		return true
	}
	defaultIndex := 0
	for index, track := range file.AudioTracks {
		if track.Default {
			defaultIndex = index
			break
		}
	}
	if audioIndex < 0 || audioIndex >= len(file.AudioTracks) {
		audioIndex = defaultIndex
	}
	return audioIndex == defaultIndex
}

func finalizePlanIdentityV3(plan *PlanV3, attemptID string, outputContextID string) {
	plan.PlanID = DeterministicPlanIDV3(attemptID, plan.RequestedMediaFileID, plan.EffectiveMediaFileID, *plan)
	plan.PlanAttemptKey = PlanAttemptKeyV3(*plan, outputContextID, nil)
}

// planAttemptedV3 compares FNV-hex attempt keys exactly after trimming
// whitespace; the keys are case-sensitive hashes, not free-form labels.
func planAttemptedV3(plan PlanV3, outputContextID string, attempted []string) bool {
	wanted := PlanAttemptKeyV3(plan, outputContextID, nil)
	for _, key := range attempted {
		if strings.TrimSpace(key) == wanted {
			return true
		}
	}
	return false
}

func terminalPlannerResultV3(reason, message string, retryable bool) PlannerResultV3 {
	return PlannerResultV3{Terminal: &TerminalV3{Reason: reason, Message: message, Retryable: retryable}, SubtitleTrackIndex: -1, SubtitleTransportTrackIndex: -1}
}
func subtitlePolicyNameV3(f SubtitleFidelityV3) string {
	if f == SubtitleFidelityPreserveV3 {
		return "require_authored_fidelity"
	}
	return "allow_simplified_rendering"
}
func floatOrZeroV3(v *float64) float64 {
	if v == nil {
		return 0
	}
	return *v
}
func intPointerV3(v int) *int {
	if v <= 0 {
		return nil
	}
	value := v
	return &value
}
func floatPointerV3(v float64) *float64 {
	if v <= 0 {
		return nil
	}
	value := v
	return &value
}
func optionalValueV3(v *int) int {
	if v == nil {
		return 0
	}
	return *v
}
func resolutionHeightV3(v string) int {
	value, _ := strconv.Atoi(strings.TrimSuffix(strings.ToLower(v), "p"))
	if strings.EqualFold(v, "4k") {
		return 2160
	}
	return value
}
func resolutionLabelV3(h int) string {
	switch {
	case h >= 2160:
		return "2160p"
	case h >= 1080:
		return "1080p"
	case h >= 720:
		return "720p"
	default:
		return "480p"
	}
}
func ladderHeightForBandwidthV3(kbps int) int {
	switch {
	case kbps >= 20_000:
		return 2160
	case kbps >= 8_000:
		return 1080
	case kbps >= 4_000:
		return 720
	default:
		return 480
	}
}
func minPositiveV3(a, b int) int {
	if a <= 0 {
		return b
	}
	if b <= 0 || a < b {
		return a
	}
	return b
}

// ladderBitrateKbpsV3 matches the established web ladder's standard shared
// rungs; 2160p is the v3-only extension until the web menu exposes a 4K
// transcode tier.
func ladderBitrateKbpsV3(height int) int {
	bitrates := map[int]int{480: 1_500, 720: 2_000, 1080: 6_000, 2160: 20_000}
	return bitrates[resolutionHeightV3(resolutionLabelV3(height))]
}

func qualityDimensionsV3(height, sourceWidth, sourceHeight int) (int, int) {
	rung := resolutionHeightV3(resolutionLabelV3(height))
	width := 0
	if sourceWidth > 0 && sourceHeight > 0 {
		width = sourceWidth * rung / sourceHeight
		width -= width % 2
	}
	if width == 0 {
		width, _ = dimensionsFromResolutionV3(resolutionLabelV3(rung))
	}
	return width, ladderBitrateKbpsV3(rung)
}

func SortedTransformationNamesV3(values []TransformationV3) []string {
	result := make([]string, 0, len(values))
	for _, v := range values {
		result = append(result, v.Name)
	}
	sort.Strings(result)
	return result
}

func deliveryAvailableV3(request StartRequestV3, deliveryClass string) bool {
	capability, ok := request.ClientPlaybackContext.Deliveries[deliveryClass]
	if !ok {
		return false
	}
	return capability.Enabled && capability.SupportedOnDevice
}

// deliverySupportsPlanV3 applies the capability limits scoped to the delivery
// class after a concrete recipe has been built. Empty lists preserve clients
// that only advertise class availability; non-empty lists are authoritative
// subsets of the top-level device capabilities.
func deliverySupportsPlanV3(request StartRequestV3, deliveryClass string, plan PlanV3) bool {
	capability, ok := request.ClientPlaybackContext.Deliveries[deliveryClass]
	if !ok || !capability.Enabled || !capability.SupportedOnDevice {
		return false
	}
	if len(capability.Containers) > 0 && !containsFoldV3(capability.Containers, plan.Stream.Container) {
		return false
	}
	if codec := strings.TrimSpace(plan.EffectiveRecipe.VideoCodec); codec != "" && len(capability.VideoCodecs) > 0 && !containsFoldV3(capability.VideoCodecs, codec) {
		return false
	}
	if codec := strings.TrimSpace(plan.EffectiveRecipe.AudioCodec); codec != "" {
		hasAudioConstraints := len(capability.AudioDecodeCodecs) > 0 || len(capability.AudioPassthroughCodecs) > 0
		if hasAudioConstraints {
			supportedCodecs := capability.AudioDecodeCodecs
			if plan.Claims.Audio.Passthrough {
				supportedCodecs = capability.AudioPassthroughCodecs
			}
			if !containsFoldV3(supportedCodecs, codec) {
				return false
			}
		}
	}
	if capability.MaxChannels != nil && plan.EffectiveRecipe.AudioChannels != nil && *plan.EffectiveRecipe.AudioChannels > *capability.MaxChannels {
		return false
	}
	if capability.HDRDetails != nil && !hdrDetailsSupportPlanV3(*capability.HDRDetails, plan) {
		return false
	}
	return true
}

func hdrDetailsSupportPlanV3(hdr HDRCapabilitiesV3, plan PlanV3) bool {
	switch plan.EffectiveRecipe.DynamicRange {
	case "", DynamicRangeSDRV3:
		return true
	case DynamicRangeHDR10V3, "hdr_unknown":
		return hdr.HDR10
	case DynamicRangeHDR10PlusV3:
		return hdr.HDR10Plus
	case DynamicRangeHLGV3:
		return hdr.HLG
	case DynamicRangeDolbyVisionV3:
		profile := plan.Source.DVProfile
		for _, transformation := range plan.Transformations {
			if transformation.Name == ClientDV7ToDV81V3 {
				profile = 8
				break
			}
		}
		return containsIntV3(hdr.DolbyVisionProfiles, profile)
	default:
		return false
	}
}
func ExplainPlannerResultV3(result PlannerResultV3) string {
	if result.Plan != nil {
		return fmt.Sprintf("%s:%s", result.Plan.Delivery, result.Plan.DecisionReason)
	}
	if result.Terminal != nil {
		return "terminal:" + result.Terminal.Reason
	}
	return "invalid"
}