//! Local-file streaming, rescan, and transcode routes.
//!
//! GET  /files/stream/:id                      — Range streaming (no auth)
//! POST /files/rescan                           — index rebuild (auth required)
//! GET  /files/transcode/:id/playlist.m3u8     — trigger transcode + serve playlist
//! GET  /files/transcode/:id/:segment           — serve .ts / .m3u8 segment
//! GET  /files/transcode-settings              — read TTL (auth)
//! PUT  /files/transcode-settings              — update TTL (auth)
//! GET  /files/transcode-stats                 — cache size (auth)
//! DELETE /files/transcode-cache               — clear cache (auth)

use axum::{
    Router,
    extract::{Path, State},
    http::HeaderMap,
    response::Response,
    routing::get,
};

use crate::{error::ApiError, state::AppState};

#[cfg(feature = "local-files")]
use axum::{
    Json,
    http::StatusCode,
    routing::{delete, post},
};
#[cfg(feature = "local-files")]
use serde::Deserialize;
#[cfg(feature = "local-files")]
use crate::{
    dto::{TranscodeSettingsResponse, TranscodeStatsResponse, UpdateTranscodeSettingsRequest},
    extractors::CurrentUser,
};

pub fn router() -> Router<AppState> {
    let r = Router::new().route("/stream/{id}", get(stream_file));
    #[cfg(feature = "local-files")]
    let r = r
        .route("/rescan", post(trigger_rescan))
        .route("/transcode/{id}/playlist.m3u8", get(transcode_playlist))
        .route("/transcode/{id}/{segment}", get(transcode_segment))
        .route(
            "/transcode-settings",
            get(get_transcode_settings).put(update_transcode_settings),
        )
        .route("/transcode-stats", get(get_transcode_stats))
        .route("/transcode-cache", delete(clear_transcode_cache));
    r
}

// ============================================================================
// Direct streaming
// ============================================================================

async fn stream_file(
    State(state): State<AppState>,
    Path(encoded_id): Path<String>,
    headers: HeaderMap,
) -> Result<Response, ApiError> {
    #[cfg(feature = "local-files")]
    {
        use axum::body::Body;
        use std::io::SeekFrom;
        use tokio::io::{AsyncReadExt as _, AsyncSeekExt as _};
        use tokio_util::io::ReaderStream;

        let root_dir = state.config.local_files_dir.as_ref().ok_or_else(|| {
            ApiError::not_implemented("LOCAL_FILES_DIR not configured")
        })?;

        let rel = infra::local_files::decode_stream_id(&encoded_id)
            .ok_or_else(|| ApiError::validation("invalid stream id"))?;

        let full_path = root_dir.join(&rel);
        let canonical_root = root_dir
            .canonicalize()
            .map_err(|e| ApiError::internal(e.to_string()))?;
        let canonical = full_path
            .canonicalize()
            .map_err(|_| ApiError::not_found("file not found"))?;
        if !canonical.starts_with(&canonical_root) {
            return Err(ApiError::Forbidden("path traversal detected".into()));
        }

        let mut file = tokio::fs::File::open(&canonical)
            .await
            .map_err(|_| ApiError::not_found("file not found"))?;
        let file_size = file
            .metadata()
            .await
            .map_err(|e| ApiError::internal(e.to_string()))?
            .len();

        let ext = canonical
            .extension()
            .and_then(|e| e.to_str())
            .unwrap_or("")
            .to_lowercase();
        let content_type = content_type_for_ext(&ext);

        let range = headers
            .get(axum::http::header::RANGE)
            .and_then(|v| v.to_str().ok())
            .and_then(|r| parse_range(r, file_size));

        let (start, end, status) = if let Some((s, e)) = range {
            (s, e.min(file_size.saturating_sub(1)), StatusCode::PARTIAL_CONTENT)
        } else {
            (0, file_size.saturating_sub(1), StatusCode::OK)
        };
        let length = end - start + 1;

        file.seek(SeekFrom::Start(start))
            .await
            .map_err(|e| ApiError::internal(e.to_string()))?;

        let stream = ReaderStream::new(file.take(length));
        let body = Body::from_stream(stream);

        let mut builder = Response::builder()
            .status(status)
            .header("Content-Type", content_type)
            .header("Content-Length", length.to_string())
            .header("Accept-Ranges", "bytes");

        if status == StatusCode::PARTIAL_CONTENT {
            builder = builder.header(
                "Content-Range",
                format!("bytes {}-{}/{}", start, end, file_size),
            );
        }

        return builder.body(body).map_err(|e| ApiError::internal(e.to_string()));
    }

    #[cfg(not(feature = "local-files"))]
    Err(ApiError::not_implemented("local-files feature not enabled"))
}

// ============================================================================
// Rescan
// ============================================================================

#[cfg(feature = "local-files")]
async fn trigger_rescan(
    State(state): State<AppState>,
    CurrentUser(_user): CurrentUser,
) -> Result<Json<serde_json::Value>, ApiError> {
    let index = state.local_index.read().await.clone()
        .ok_or_else(|| ApiError::not_implemented("no local files provider active"))?;
    let count = index.rescan().await;
    Ok(Json(serde_json::json!({ "items_found": count })))
}

// ============================================================================
// Transcode endpoints
// ============================================================================

#[cfg(feature = "local-files")]
async fn transcode_playlist(
    State(state): State<AppState>,
    Path(id): Path<String>,
) -> Result<Response, ApiError> {
    let tm = state.transcode_manager.read().await.clone()
        .ok_or_else(|| ApiError::not_implemented("TRANSCODE_DIR not configured"))?;

    let root = state.config.local_files_dir.as_ref().ok_or_else(|| {
        ApiError::not_implemented("LOCAL_FILES_DIR not configured")
    })?;

    let rel = infra::local_files::decode_stream_id(&id)
        .ok_or_else(|| ApiError::validation("invalid item id"))?;
    let src = root.join(&rel);

    tm.ensure_transcoded(&id, &src)
        .await
        .map_err(|e| ApiError::internal(e.to_string()))?;

    let playlist_path = tm.transcode_dir.join(&id).join("playlist.m3u8");
    let content = tokio::fs::read_to_string(&playlist_path)
        .await
        .map_err(|e| ApiError::internal(e.to_string()))?;

    Response::builder()
        .status(200)
        .header("Content-Type", "application/vnd.apple.mpegurl")
        .header("Cache-Control", "no-cache")
        .body(axum::body::Body::from(content))
        .map_err(|e| ApiError::internal(e.to_string()))
}

#[derive(Deserialize)]
#[cfg(feature = "local-files")]
struct TranscodeSegmentPath {
    id: String,
    segment: String,
}

#[cfg(feature = "local-files")]
async fn transcode_segment(
    State(state): State<AppState>,
    Path(params): Path<TranscodeSegmentPath>,
) -> Result<Response, ApiError> {
    let TranscodeSegmentPath { id, segment } = params;

    let ext = std::path::Path::new(&segment)
        .extension()
        .and_then(|e| e.to_str())
        .unwrap_or("");
    if ext != "ts" && ext != "m3u8" {
        return Err(ApiError::not_found("invalid segment extension"));
    }
    if segment.contains('/') || segment.contains("..") {
        return Err(ApiError::Forbidden("invalid segment path".into()));
    }

    let tm = state.transcode_manager.read().await.clone()
        .ok_or_else(|| ApiError::not_implemented("TRANSCODE_DIR not configured"))?;

    let file_path = tm.transcode_dir.join(&id).join(&segment);
    let canonical_base = tm
        .transcode_dir
        .canonicalize()
        .map_err(|e| ApiError::internal(e.to_string()))?;
    let canonical_file = file_path
        .canonicalize()
        .map_err(|_| ApiError::not_found("segment not found"))?;
    if !canonical_file.starts_with(&canonical_base) {
        return Err(ApiError::Forbidden("path traversal detected".into()));
    }

    let content = tokio::fs::read(&canonical_file)
        .await
        .map_err(|_| ApiError::not_found("segment not found"))?;

    let content_type = if ext == "ts" {
        "video/mp2t"
    } else {
        "application/vnd.apple.mpegurl"
    };

    Response::builder()
        .status(200)
        .header("Content-Type", content_type)
        .body(axum::body::Body::from(content))
        .map_err(|e| ApiError::internal(e.to_string()))
}

// ============================================================================
// Transcode settings / stats / cache management
// ============================================================================

#[cfg(feature = "local-files")]
async fn get_transcode_settings(
    State(state): State<AppState>,
    CurrentUser(_user): CurrentUser,
) -> Result<Json<TranscodeSettingsResponse>, ApiError> {
    let tm = state.transcode_manager.read().await.clone()
        .ok_or_else(|| ApiError::not_implemented("TRANSCODE_DIR not configured"))?;
    Ok(Json(TranscodeSettingsResponse {
        cleanup_ttl_hours: tm.get_cleanup_ttl(),
    }))
}

#[cfg(feature = "local-files")]
async fn update_transcode_settings(
    State(state): State<AppState>,
    CurrentUser(_user): CurrentUser,
    Json(req): Json<UpdateTranscodeSettingsRequest>,
) -> Result<Json<TranscodeSettingsResponse>, ApiError> {
    if let Some(repo) = &state.transcode_settings_repo {
        repo.save_cleanup_ttl(req.cleanup_ttl_hours)
            .await
            .map_err(|e| ApiError::internal(e.to_string()))?;
    }

    let tm_opt = state.transcode_manager.read().await.clone();
    if let Some(tm) = tm_opt {
        tm.set_cleanup_ttl(req.cleanup_ttl_hours);
    }

    Ok(Json(TranscodeSettingsResponse {
        cleanup_ttl_hours: req.cleanup_ttl_hours,
    }))
}

#[cfg(feature = "local-files")]
async fn get_transcode_stats(
    State(state): State<AppState>,
    CurrentUser(_user): CurrentUser,
) -> Result<Json<TranscodeStatsResponse>, ApiError> {
    let tm = state.transcode_manager.read().await.clone()
        .ok_or_else(|| ApiError::not_implemented("TRANSCODE_DIR not configured"))?;
    let (cache_size_bytes, item_count) = tm.cache_stats().await;
    Ok(Json(TranscodeStatsResponse {
        cache_size_bytes,
        item_count,
    }))
}

#[cfg(feature = "local-files")]
async fn clear_transcode_cache(
    State(state): State<AppState>,
    CurrentUser(_user): CurrentUser,
) -> Result<StatusCode, ApiError> {
    let tm = state.transcode_manager.read().await.clone()
        .ok_or_else(|| ApiError::not_implemented("TRANSCODE_DIR not configured"))?;
    tm.clear_cache()
        .await
        .map_err(|e| ApiError::internal(e.to_string()))?;
    Ok(StatusCode::NO_CONTENT)
}

// ============================================================================
// Helpers
// ============================================================================

fn content_type_for_ext(ext: &str) -> &'static str {
    match ext {
        "mp4" | "m4v" => "video/mp4",
        "mkv" => "video/x-matroska",
        "avi" => "video/x-msvideo",
        "mov" => "video/quicktime",
        "webm" => "video/webm",
        _ => "application/octet-stream",
    }
}

fn parse_range(range: &str, file_size: u64) -> Option<(u64, u64)> {
    let range = range.strip_prefix("bytes=")?;
    let (start_str, end_str) = range.split_once('-')?;
    let start: u64 = start_str.parse().ok()?;
    let end: u64 = if end_str.is_empty() {
        file_size.saturating_sub(1)
    } else {
        end_str.parse().ok()?
    };
    if start > end || start >= file_size {
        return None;
    }
    Some((start, end))
}