use crate::model::{
    user_command::UserCommand, ActiveUserConnectionChange, ConfigType, LibraryScanProgressEvent, PermissionSet,
    PlaylistUpdateProgressEvent, PlaylistUpdateRunStateEvent, QueueRevision, RecordingTaskDto, StatusCheck,
    StreamMeterEntry, SystemInfo,
};
use bytes::Bytes;
use serde::{Deserialize, Serialize};
use std::{io, sync::Arc};

// Version 4 carries correlated run objects in PlaylistUpdateResponse. Version 3
// clients expect a bare state and must reconnect with an updated frontend.
pub const PROTOCOL_VERSION: u8 = 4;

#[derive(Default, PartialOrd, PartialEq, Debug, Clone)]
pub enum UserRole {
    #[default]
    Unauthorized,
    Admin,
    User,
}

impl UserRole {
    pub fn is_admin(&self) -> bool { self.eq(&UserRole::Admin) }
    pub fn is_user(&self) -> bool { self.eq(&UserRole::User) }
}

#[derive(Default)]
pub struct ProtocolHandlerMemory {
    pub token: Option<String>,
    pub permissions: PermissionSet,
    pub role: UserRole,
    pub subject_id: Option<String>,
    pub stream_meter_subscribed: bool,
}

pub enum ProtocolHandler {
    Version(u8),
    Default(ProtocolHandlerMemory),
}

pub enum WsCloseCode {
    // Normal,
    // Away,
    Protocol,
    // Unsupported,
    // Abnormal,
    // Invalid,
    // Policy,
    // Size,
    // Extension,
    // Error,
    // Restart,
    // Again,
    // Tls,
}

impl WsCloseCode {
    pub fn code(&self) -> u16 {
        match self {
            // WsCloseCode::Normal => 1000,
            // WsCloseCode::Away => 1001,
            WsCloseCode::Protocol => 1002,
            // WsCloseCode::Unsupported => 1003,
            // WsCloseCode::Abnormal => 1006,
            // WsCloseCode::Invalid => 1007,
            // WsCloseCode::Policy => 1008,
            // WsCloseCode::Size => 1009,
            // WsCloseCode::Extension => 1010,
            // WsCloseCode::Error => 1011,
            // WsCloseCode::Restart => 1012,
            // WsCloseCode::Again => 1013,
            // WsCloseCode::Tls => 1015,
        }
    }
}

#[allow(clippy::large_enum_variant)]
#[derive(Serialize, Deserialize, Debug)]
pub enum ProtocolMessage {
    Unauthorized,
    Error(String),
    Version(u8),
    Auth(String),
    Authorized,
    StreamMeterSubscribe,
    StreamMeterUnsubscribe,
    ServerError(String),
    StatusRequest(String),
    UserAction(UserCommand),
    // Responses
    StatusResponse(StatusCheck),
    ActiveUserResponse(ActiveUserConnectionChange),
    ActiveProviderResponse(Arc<str>, usize), // single provider
    ActiveProviderCountRequest(String),
    ActiveProviderCountResponse(usize),
    ConfigChangeResponse(ConfigType),
    PlaylistUpdateResponse(PlaylistUpdateRunStateEvent),
    PlaylistUpdateProgressResponse(PlaylistUpdateProgressEvent),
    UserActionResponse(bool),
    SystemInfoResponse(SystemInfo),
    LibraryScanProgressResponse(LibraryScanProgressEvent),
    StreamMeterBatchResponse(Vec<StreamMeterEntry>),
    /// Owner-filtered recording snapshot. The frontend requests one on
    /// connect and after a revision gap; the server publishes a full
    /// filtered list on every change. There is deliberately no delta
    /// message: a partial list must never be mistaken for a snapshot.
    RecordingSnapshotRequest,
    RecordingSnapshotResponse {
        revision: QueueRevision,
        /// Whether the DVR can accept work at all. Carried here so a
        /// client never has to poll a separate availability route.
        available: bool,
        quota: crate::model::RecordingQuotaSummaryDto,
        tasks: Vec<RecordingTaskDto>,
    },
    /// Notification that the rule repository changed. The frontend
    /// re-fetches `/api/v1/recording/rules` on receipt. No payload
    /// — the rule list is small and the GET is cheap.
    RecordingRulesChanged,
    /// Inputs in maintenance after a change. Carries the whole map: it is small,
    /// and a client never has to merge.
    MaintenanceChangedResponse(crate::model::MaintenanceEntries),
    /// The socket cannot serve recordings to this session, and the reason
    /// is actionable.
    ///
    /// Without this frame the socket answered every refusal with an empty
    /// task list, so a client whose token predated a permission-schema
    /// bump could not tell "you have no recordings" from "your token is
    /// too old to be trusted" — and sat on an empty library forever.
    /// `code` is the same stable code the REST routes return
    /// (`recording_token_refresh_required`, `recording_disabled`), so the
    /// frontend maps both surfaces through one table.
    RecordingWsError {
        code: String,
    },
}

impl ProtocolMessage {
    pub fn to_bytes(&self) -> io::Result<Bytes> {
        if let ProtocolMessage::Version(version) = self {
            Ok(Bytes::from(vec![*version]))
        } else {
            //let encoded = bincode_serialize(self)?;
            let json = serde_json::to_string(self).map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))?;
            Ok(Bytes::from(json.into_bytes()))
        }
    }

    pub fn from_bytes(bytes: Bytes) -> io::Result<Self> {
        if bytes.len() == 1 {
            Ok(ProtocolMessage::Version(bytes[0]))
        } else {
            //bincode_deserialize::<ProtocolMessage>(bytes.as_ref())
            let s = std::str::from_utf8(&bytes).map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))?;
            serde_json::from_str(s).map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))
        }
    }
}

#[cfg(test)]
mod tests {
    use super::{ProtocolMessage, PROTOCOL_VERSION};
    use crate::model::{PlaylistUpdateRunStateEvent, PlaylistUpdateState};
    use bytes::Bytes;

    #[test]
    fn playlist_update_protocol_version_distinguishes_legacy_clients() {
        assert_eq!(PROTOCOL_VERSION, 4);
        assert_eq!(ProtocolMessage::Version(PROTOCOL_VERSION).to_bytes().unwrap().as_ref(), &[4]);
        let ProtocolMessage::Version(legacy) = ProtocolMessage::from_bytes(Bytes::from_static(&[3])).unwrap() else {
            panic!("expected a protocol handshake");
        };
        assert_ne!(legacy, PROTOCOL_VERSION, "the server's version gate must reject legacy clients");
    }

    #[test]
    fn playlist_update_protocol_preserves_correlated_frames_and_legacy_decoding() {
        for state in [PlaylistUpdateState::Success, PlaylistUpdateState::Partial, PlaylistUpdateState::Failure] {
            let event = PlaylistUpdateRunStateEvent::correlated("review-run".into(), 17.into(), state);
            let bytes = ProtocolMessage::PlaylistUpdateResponse(event.clone()).to_bytes().unwrap();
            let ProtocolMessage::PlaylistUpdateResponse(decoded) = ProtocolMessage::from_bytes(bytes).unwrap() else {
                panic!("expected a correlated playlist update frame");
            };
            assert_eq!(decoded, event);

            let legacy = serde_json::to_vec(&serde_json::json!({"PlaylistUpdateResponse": state})).unwrap();
            let ProtocolMessage::PlaylistUpdateResponse(decoded) =
                ProtocolMessage::from_bytes(Bytes::from(legacy)).unwrap()
            else {
                panic!("expected a legacy playlist update frame");
            };
            assert_eq!(decoded, PlaylistUpdateRunStateEvent::uncorrelated(state));
        }
    }
}