"""Audio stream — serves individual tracks with seek support.

The frontend requests /api/stream/next to get the next track, then plays
it via /api/stream/play/<id>. This gives the browser proper Content-Length
and Range headers for seeking.
"""

import os
import random
import re

from flask import Blueprint, jsonify, request, send_file

from ..config import BASE_DIR

bp = Blueprint("stream", __name__)

MUSIC_DIR = os.path.join(BASE_DIR, "media", "music")
FALLBACK_DIR = os.path.join(BASE_DIR, "media", "fallback")
QUEUE_DIR = os.path.join(BASE_DIR, "state", "queue")

# Playlist state — shuffled list with current index
_playlist = []
_playlist_index = 0


def _find_mp3s():
    """Collect all MP3 files from music and fallback dirs."""
    files = []
    for root_dir in (MUSIC_DIR, FALLBACK_DIR):
        if not os.path.isdir(root_dir):
            continue
        for dirpath, _dirs, filenames in os.walk(root_dir):
            for f in filenames:
                if f.lower().endswith(".mp3"):
                    files.append(os.path.join(dirpath, f))
    return files


def _find_queue_files():
    """Collect queued podcast files (priority playback)."""
    if not os.path.isdir(QUEUE_DIR):
        return []
    files = []
    for f in sorted(os.listdir(QUEUE_DIR)):
        full = os.path.join(QUEUE_DIR, f)
        if os.path.isfile(full) and f.lower().endswith(".mp3"):
            files.append(full)
    return files


def _title_from_path(path):
    """Extract a display title from a file path."""
    name = os.path.splitext(os.path.basename(path))[0]
    # Strip queue prefix: 20260313_182201_000001_filename -> filename
    queue_match = re.match(r"^\d{8}_\d{6}_\d{6}_(.+)$", name)
    if queue_match:
        name = queue_match.group(1)
    # Strip leading track numbers like "01. " or "22. "
    if len(name) > 3 and name[0:2].isdigit() and name[2] in "._ ":
        name = name[3:].strip()
    elif len(name) > 4 and name[0:3].isdigit() and name[3] in "._ ":
        name = name[4:].strip()
    name = name.replace("_", " ").replace("-", " ")
    return name


def _make_track_id(path):
    """Create a safe ID from a path for URL use."""
    # Use path relative to BASE_DIR
    try:
        rel = os.path.relpath(path, BASE_DIR)
    except ValueError:
        rel = os.path.basename(path)
    return rel.replace("\\", "/")


def _resolve_track_id(track_id):
    """Resolve a track ID back to an absolute path, with safety checks."""
    # Prevent path traversal
    if ".." in track_id:
        return None
    path = os.path.normpath(os.path.join(BASE_DIR, track_id))
    # Must be under BASE_DIR
    if not path.startswith(os.path.normpath(str(BASE_DIR))):
        return None
    if not os.path.isfile(path):
        return None
    return path


def _next_track():
    """Get the next track to play. Queue first, then shuffled music."""
    global _playlist, _playlist_index

    # Check podcast queue first
    queue_files = _find_queue_files()
    if queue_files:
        path = queue_files[0]
        return {
            "id": _make_track_id(path),
            "title": _title_from_path(path),
            "file": os.path.basename(path),
            "source": "queue",
            "size": os.path.getsize(path),
        }

    # Shuffled music
    if not _playlist or _playlist_index >= len(_playlist):
        _playlist = _find_mp3s()
        if not _playlist:
            return None
        random.shuffle(_playlist)
        _playlist_index = 0

    path = _playlist[_playlist_index]
    _playlist_index += 1

    # Verify file still exists
    if not os.path.isfile(path):
        return _next_track()

    return {
        "id": _make_track_id(path),
        "title": _title_from_path(path),
        "file": os.path.basename(path),
        "source": "music",
        "size": os.path.getsize(path),
    }


@bp.route("/stream/next")
def next_track():
    """Return metadata for the next track to play."""
    track = _next_track()
    if not track:
        return jsonify({"error": "No tracks available"}), 404
    return jsonify(track)


@bp.route("/stream/play/<path:track_id>")
def play_track(track_id):
    """Serve an MP3 file with Range support for seeking."""
    path = _resolve_track_id(track_id)
    if not path:
        return jsonify({"error": "Track not found"}), 404
    return send_file(
        path,
        mimetype="audio/mpeg",
        conditional=True,
    )


@bp.route("/stream/done", methods=["POST"])
def mark_done():
    """Remove a queue file after it finishes playing."""
    data = request.get_json() or {}
    track_id = data.get("id")
    if not track_id:
        return jsonify({"error": "Missing id"}), 400
    path = _resolve_track_id(track_id)
    if path and os.path.normpath(QUEUE_DIR) in os.path.normpath(path):
        try:
            os.remove(path)
        except OSError:
            pass
    return jsonify({"ok": True})


@bp.route("/stream/skip", methods=["POST"])
def skip():
    """Skip the current queue item (user-initiated)."""
    queue_files = _find_queue_files()
    if queue_files:
        try:
            os.remove(queue_files[0])
        except OSError:
            pass
    return jsonify({"ok": True})