package handlers

import (
	"encoding/json"
	"errors"
	"fmt"
	"log/slog"
	"net/http"
	"strconv"
	"strings"
	"time"

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

type CatalogHandler struct {
	resolver *catalog.CatalogResolver
	itemsH   *ItemsHandler
}

func NewCatalogHandler(resolver *catalog.CatalogResolver, itemsH *ItemsHandler) *CatalogHandler {
	return &CatalogHandler{
		resolver: resolver,
		itemsH:   itemsH,
	}
}

type catalogResponse struct {
	Total      int                `json:"total"`
	TotalExact bool               `json:"total_exact"`
	HasMore    bool               `json:"has_more"`
	Items      []itemListResponse `json:"items"`
	Snapshot   string             `json:"snapshot,omitempty"`
}

type catalogFiltersResponse struct {
	Genres            []string  `json:"genres"`
	Studios           []string  `json:"studios"`
	Networks          []string  `json:"networks"`
	Countries         []string  `json:"countries"`
	OriginalLanguages []string  `json:"original_languages"`
	ContentRatings    []string  `json:"content_ratings"`
	Resolutions       *[]string `json:"resolutions,omitempty"`
	AudioLanguages    *[]string `json:"audio_languages,omitempty"`
	SubtitleLanguages *[]string `json:"subtitle_languages,omitempty"`
}

func (h *CatalogHandler) HandleGetCatalog(w http.ResponseWriter, r *http.Request) {
	if h == nil || h.resolver == nil || h.itemsH == nil {
		writeError(w, http.StatusInternalServerError, "internal_error", "Catalog is not configured")
		return
	}

	req, err := catalog.ParseCatalogRequest(r.URL.Query())
	if err != nil {
		writeError(w, http.StatusBadRequest, "bad_request", err.Error())
		return
	}

	result, err := h.resolver.Resolve(r.Context(), req, h.itemsH.accessFilter(r))
	if err != nil {
		if errors.Is(err, catalog.ErrInvalidCatalogRequest) {
			writeError(w, http.StatusBadRequest, "bad_request", err.Error())
			return
		}
		if errors.Is(err, catalog.ErrCatalogSourceNotFound) {
			writeError(w, http.StatusNotFound, "not_found", "Catalog source not found")
			return
		}
		slog.Error("catalog: resolve failed", "err_msg", err.Error())
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to resolve catalog")
		return
	}

	overlaySummaries := h.itemsH.listOverlaySummaries(r.Context(), result.Items, h.itemsH.accessFilter(r))
	userStates := h.itemsH.listItemUserStates(r, result.Items)
	episodeMetadata := h.itemsH.listEpisodeBrowseMetadata(r.Context(), result.Items)
	items := make([]itemListResponse, 0, len(result.Items))
	for _, item := range result.Items {
		resp := h.itemsH.toItemListResponseWithOverlay(
			r,
			item,
			overlaySummaries[item.ContentID],
			userStates[item.ContentID],
		)
		if meta, ok := episodeMetadata[item.ContentID]; ok {
			resp.SeriesTitle = meta.SeriesTitle
			resp.SeasonNumber = meta.SeasonNumber
			resp.EpisodeNumber = meta.EpisodeNumber
		}
		items = append(items, resp)
	}

	var snapshot string
	if !result.SnapshotAt.IsZero() {
		snapshot = result.SnapshotAt.Format(time.RFC3339Nano)
	}

	writeJSON(w, http.StatusOK, catalogResponse{
		Total:      result.Total,
		TotalExact: result.TotalExact,
		HasMore:    result.HasMore,
		Items:      items,
		Snapshot:   snapshot,
	})
}

func (h *CatalogHandler) HandleGetCatalogFilters(w http.ResponseWriter, r *http.Request) {
	if h == nil || h.resolver == nil || h.itemsH == nil {
		writeError(w, http.StatusInternalServerError, "internal_error", "Catalog is not configured")
		return
	}

	req, err := catalog.ParseCatalogRequest(r.URL.Query())
	if err != nil {
		writeError(w, http.StatusBadRequest, "bad_request", err.Error())
		return
	}

	includeTechnical := parseIncludeTechnical(r.URL.Query().Get("include_technical"))
	filters, err := h.resolver.ListFiltersWithOptions(
		r.Context(),
		req,
		h.itemsH.accessFilter(r),
		catalog.CatalogFilterOptions{IncludeTechnical: includeTechnical},
	)
	if err != nil {
		if errors.Is(err, catalog.ErrInvalidCatalogRequest) {
			writeError(w, http.StatusBadRequest, "bad_request", err.Error())
			return
		}
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to list catalog filters")
		return
	}

	var resolutions *[]string
	var audioLanguages *[]string
	var subtitleLanguages *[]string
	if includeTechnical {
		resolutions = &filters.Resolutions
		audioLanguages = &filters.AudioLanguages
		subtitleLanguages = &filters.SubtitleLanguages
	}

	writeJSON(w, http.StatusOK, catalogFiltersResponse{
		Genres:            filters.Genres,
		Studios:           filters.Studios,
		Networks:          filters.Networks,
		Countries:         filters.Countries,
		OriginalLanguages: filters.OriginalLanguages,
		ContentRatings:    filters.ContentRatings,
		Resolutions:       resolutions,
		AudioLanguages:    audioLanguages,
		SubtitleLanguages: subtitleLanguages,
	})
}

func parseIncludeTechnical(raw string) bool {
	if strings.TrimSpace(raw) == "" {
		return true
	}
	includeTechnical, err := strconv.ParseBool(raw)
	if err != nil {
		return true
	}
	return includeTechnical
}

func (h *CatalogHandler) HandlePostCatalogQuery(w http.ResponseWriter, r *http.Request) {
	if h == nil || h.itemsH == nil || h.itemsH.browseRepo == nil {
		writeError(w, http.StatusInternalServerError, "internal_error", "Catalog is not configured")
		return
	}

	var req filterItemsRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "bad_request", "Invalid request body")
		return
	}

	if req.Limit <= 0 {
		req.Limit = 20
	}
	if req.Limit > 100 {
		req.Limit = 100
	}

	fb := sections.NewFilterBuilder("mi")
	filterWhere, filterArgs, err := fb.Build(req.FilterConfig)
	if err != nil {
		writeError(w, http.StatusBadRequest, "bad_request", "Invalid filter: "+err.Error())
		return
	}

	accessFilter := h.itemsH.accessFilter(r)
	if req.LibraryID > 0 {
		accessFilter.PresentationLibraryID = &req.LibraryID
	}
	libraryIDs := accessFilter.AllowedLibraryIDs

	var conditions []string
	args := filterArgs
	argIdx := fb.ArgIdx()

	if filterWhere != "" {
		conditions = append(conditions, filterWhere)
	}

	disabledLibraryIDs := accessFilter.DisabledLibraryIDs
	fromClause := "media_items mi"
	if libraryIDs != nil || req.LibraryID > 0 || len(disabledLibraryIDs) > 0 {
		fromClause = "media_items mi JOIN media_item_libraries mil ON mi.content_id = mil.content_id"
	}

	if req.LibraryID > 0 {
		conditions = append(conditions, fmt.Sprintf("mil.media_folder_id = $%d", argIdx))
		args = append(args, req.LibraryID)
		argIdx++
	}

	if libraryIDs != nil {
		if len(libraryIDs) == 0 {
			writeJSON(w, http.StatusOK, browseResponse{Items: []itemListResponse{}, Total: 0})
			return
		}
		conditions = append(conditions, fmt.Sprintf("mil.media_folder_id = ANY($%d)", argIdx))
		args = append(args, libraryIDs)
		argIdx++
	}
	if len(disabledLibraryIDs) > 0 {
		conditions = append(conditions, fmt.Sprintf("NOT (mil.media_folder_id = ANY($%d))", argIdx))
		args = append(args, disabledLibraryIDs)
		argIdx++
	}
	catalog.ApplySectionAccessFilter("mi", catalog.AccessFilter{MaxContentRating: accessFilter.MaxContentRating}, &conditions, &args, &argIdx)

	whereClause := ""
	if len(conditions) > 0 {
		whereClause = "WHERE " + strings.Join(conditions, " AND ")
	}

	sortClause := "ORDER BY mi.created_at DESC"
	if req.Sort != "" {
		sortClause = filterSortClause(req.Sort, req.Order)
	}

	// Single-pass query: COUNT(*) OVER () returns the same total on every
	// row of the filtered set, so we read it once from the first scanned row
	// instead of firing a separate SELECT COUNT(*).
	query := fmt.Sprintf(
		`SELECT %s, COUNT(*) OVER () AS total_count FROM %s %s %s LIMIT $%d OFFSET $%d`,
		filterItemColumns("mi"), fromClause, whereClause, sortClause, argIdx, argIdx+1,
	)
	args = append(args, req.Limit, req.Offset)

	rows, err := h.itemsH.browseRepo.Pool().Query(r.Context(), query, args...)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to query items")
		return
	}
	defer rows.Close()

	var total int
	modelItems := make([]*models.MediaItem, 0)
	for rows.Next() {
		var item models.MediaItem
		var rowTotal int
		scanErr := rows.Scan(
			&item.ContentID, &item.Type, &item.Title, &item.SortTitle, &item.OriginalTitle,
			&item.Year, &item.Genres, &item.ContentRating, &item.Runtime, &item.Overview, &item.Tagline,
			&item.RatingIMDB, &item.RatingTMDB, &item.RatingRTCritic, &item.RatingRTAudience,
			&item.ImdbID, &item.TmdbID, &item.TvdbID,
			&item.PosterPath, &item.PosterThumbhash, &item.BackdropPath, &item.BackdropThumbhash, &item.LogoPath,
			&item.MetadataS3Path, &item.MetadataEtag, &item.SeasonCount,
			&item.Studios, &item.Networks, &item.Countries, &item.FirstAirDate, &item.LastAirDate,
			&item.MatchedAt, &item.Status, &item.CreatedAt, &item.UpdatedAt,
			&rowTotal,
		)
		if scanErr != nil {
			writeError(w, http.StatusInternalServerError, "internal_error", "Failed to scan item")
			return
		}
		modelItems = append(modelItems, &item)
		total = rowTotal
	}

	// COUNT(*) OVER () emits no rows when the data SELECT is empty, so total
	// stays 0 even when the broader result set has matching rows (e.g. OFFSET
	// past the last page). Re-query the count to give callers the real total.
	// Skip when offset == 0 because in that case an empty page genuinely means
	// total = 0. Mirrors the fallback in browse.go / query_executor.go /
	// favorites_browse.go / item_repo.go Search.
	if len(modelItems) == 0 && req.Offset > 0 {
		countQuery := fmt.Sprintf(
			"SELECT COUNT(*) FROM (SELECT 1 FROM %s %s) sub",
			fromClause, whereClause,
		)
		// Drop the trailing limit, offset args from the data query.
		countArgs := args[:len(args)-2]
		if err := h.itemsH.browseRepo.Pool().QueryRow(r.Context(), countQuery, countArgs...).Scan(&total); err != nil {
			writeError(w, http.StatusInternalServerError, "internal_error", "Failed to count items")
			return
		}
	}

	userStates := h.itemsH.listItemUserStates(r, modelItems)
	items := make([]itemListResponse, 0, len(modelItems))
	for _, item := range modelItems {
		if h.itemsH.detailSvc != nil {
			if localized, locErr := h.itemsH.detailSvc.LocalizeItemModel(r.Context(), item, accessFilter); locErr == nil && localized != nil {
				item = localized
			}
		}
		items = append(items, h.itemsH.toItemListResponseWithOverlay(r, item, nil, userStates[item.ContentID]))
	}

	writeJSON(w, http.StatusOK, browseResponse{
		Total:   total,
		HasMore: req.Offset+req.Limit < total,
		Items:   items,
	})
}

func (h *CatalogHandler) HandleLegacySearch(w http.ResponseWriter, r *http.Request) {
	if h == nil || h.itemsH == nil || h.itemsH.itemRepo == nil {
		writeError(w, http.StatusInternalServerError, "internal_error", "Catalog is not configured")
		return
	}

	if values, ok := buildLegacySearchCatalogValues(r.URL.Query()); ok && h.resolver != nil {
		h.itemsH.writeCatalogBrowseResponse(w, r, values)
		return
	}

	query := strings.TrimSpace(r.URL.Query().Get("q"))
	if query == "" {
		writeError(w, http.StatusBadRequest, "bad_request", "Search query 'q' is required")
		return
	}

	limit := catalog.ParseIntParam(r.URL.Query().Get("limit"))
	if limit <= 0 {
		limit = 20
	}
	if limit > 100 {
		limit = 100
	}
	offset := max(catalog.ParseIntParam(r.URL.Query().Get("offset")), 0)

	items, total, err := h.itemsH.itemRepo.Search(r.Context(), query, parseSearchTypes(r.URL.Query()["type"]), limit, offset, h.itemsH.accessFilter(r))
	if err != nil {
		slog.Error("search failed", "query", query, "error", err)
		writeError(w, http.StatusInternalServerError, "internal_error", "Search failed")
		return
	}

	userStates := h.itemsH.listItemUserStates(r, items)
	resp := make([]itemListResponse, 0, len(items))
	for _, item := range items {
		resp = append(resp, h.itemsH.toItemListResponseWithOverlay(r, item, nil, userStates[item.ContentID]))
	}

	writeJSON(w, http.StatusOK, browseResponse{
		Total:   total,
		HasMore: offset+len(resp) < total,
		Items:   resp,
	})
}