#!/usr/bin/env python3
"""
update_playlists.py - Select the next unplayed episode per show and write an
annotated URI queue file for station.liq to consume.

Concurrency model mirrors fetch_podcasts.py: shares the same exclusive
lockfile (state/radio.lock); skips cleanly if the fetcher holds it. Databases
run in WAL mode with a busy timeout as a second safety net.

Selection: for each show, pick the earliest episode with played=0, write
playlists/<slug>.txt as a single annotated URI line, then mark it played.
Works identically for archived (local file_path) and live (enclosure_url)
shows because both store their episodes in the same table.
"""

import argparse
import fcntl
import json
import logging
import os
import sqlite3
import sys
from pathlib import Path

ROOT = Path(__file__).resolve().parent
CONFIG_PATH = ROOT / "config.json"

STATE_DIR = None
SUBS_DB = None
PLAYED_DB = None
PODCASTS_DIR = None
LOGS_DIR = None
PLAYLISTS_DIR = None
LOCK_FILE = None

def load_config():
    with open(CONFIG_PATH) as f:
        return json.load(f)

def init_paths():
    global STATE_DIR, SUBS_DB, PLAYED_DB, PODCASTS_DIR, LOGS_DIR, PLAYLISTS_DIR, LOCK_FILE
    cfg = load_config()
    storage = Path(cfg["storage"]).expanduser().resolve()
    STATE_DIR = storage / "state"
    SUBS_DB = STATE_DIR / "subscriptions.db"
    PLAYED_DB = STATE_DIR / "played.db"
    PODCASTS_DIR = storage / "podcasts"
    LOGS_DIR = storage / "logs"
    PLAYLISTS_DIR = storage / "playlists"
    LOCK_FILE = STATE_DIR / "radio.lock"

logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s [%(levelname)s] %(message)s",
    handlers=[logging.StreamHandler(sys.stdout)],
)
log = logging.getLogger("update_playlists")

def log_error(msg):
    log.error(msg)

def _setup_logging():
    fh = logging.FileHandler(LOGS_DIR / "update.log")
    fh.setFormatter(logging.Formatter("%(asctime)s [%(levelname)s] %(message)s"))
    log.addHandler(fh)

# Shared schema definitions (must match fetch_podcasts.py).
SHOWS_COLUMNS = {
    "slug":        "TEXT PRIMARY KEY",
    "guid":        "TEXT NOT NULL UNIQUE",
    "name":        "TEXT NOT NULL",
    "feed_url":    "TEXT NOT NULL UNIQUE",
    "source":      "TEXT DEFAULT 'manual'",
    "opml_import": "INTEGER DEFAULT 0",
    "archived":    "INTEGER DEFAULT 1",
    "media_class": "TEXT",
    "created_at":  "TEXT DEFAULT (datetime('now'))",
}

EPISODES_COLUMNS = {
    "id":            "INTEGER PRIMARY KEY AUTOINCREMENT",
    "show_slug":     "TEXT NOT NULL",
    "guid":          "TEXT NOT NULL",
    "title":         "TEXT",
    "file_path":     "TEXT",
    "enclosure_url": "TEXT",
    "runlength":     "INTEGER",
    "played":        "INTEGER DEFAULT 0",
    "played_at":     "TEXT",
}

def _connect(db_path):
    conn = sqlite3.connect(str(db_path), timeout=5.0)
    conn.row_factory = sqlite3.Row
    conn.execute("PRAGMA journal_mode=WAL")
    conn.execute("PRAGMA busy_timeout=5000")
    return conn

def _ensure_columns(conn, table, columns):
    exists = conn.execute(
        "SELECT name FROM sqlite_master WHERE type='table' AND name=?", (table,)
    ).fetchone()
    if exists is None:
        defs = ",\n        ".join(f"{name} {spec}" for name, spec in columns.items())
        extra = "\n        ,UNIQUE(show_slug, guid)" if table == "episodes" else ""
        conn.execute(f"CREATE TABLE {table} (\n        {defs}{extra}\n    )")
    else:
        existing = {row[1] for row in conn.execute(f"PRAGMA table_info({table})")}
        for name, spec in columns.items():
            if name not in existing:
                col_default = spec.split("DEFAULT", 1)[1].strip() if "DEFAULT" in spec else "NULL"
                conn.execute(f"ALTER TABLE {table} ADD COLUMN {name} {col_default}")
    conn.commit()

def open_subs_db():
    conn = _connect(SUBS_DB)
    _ensure_columns(conn, "shows", SHOWS_COLUMNS)
    return conn

def open_played_db():
    conn = _connect(PLAYED_DB)
    _ensure_columns(conn, "episodes", EPISODES_COLUMNS)
    conn.execute(
        "CREATE INDEX IF NOT EXISTS idx_episodes_show_played ON episodes (show_slug, played)"
    )
    conn.commit()
    return conn

_lock_fd = None

def acquire_lock():
    global _lock_fd
    STATE_DIR.mkdir(parents=True, exist_ok=True)
    fd = os.open(str(LOCK_FILE), os.O_CREAT | os.O_RDWR, 0o644)
    try:
        fcntl.flock(fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
    except OSError:
        os.close(fd)
        return False
    os.ftruncate(fd, 0)
    os.write(fd, str(os.getpid()).encode())
    _lock_fd = fd
    return True

def release_lock():
    global _lock_fd
    if _lock_fd is not None:
        try:
            fcntl.flock(_lock_fd, fcntl.LOCK_UN)
            os.close(_lock_fd)
        finally:
            _lock_fd = None

def _annotate_uri(runlength, title, uri):
    def q(v):
        return '"' + str(v).replace('"', '\\"') + '"'
    ann = f"annotate:liq_runlength={q(runlength)},liq_title={q(title)}:"
    return ann + uri

def select_next_episode(slug, played_db):
    return played_db.execute(
        "SELECT guid, title, file_path, enclosure_url, runlength "
        "FROM episodes WHERE show_slug=? AND played=0 ORDER BY id ASC LIMIT 1",
        (slug,),
    ).fetchone()

def mark_as_played(slug, guid, played_db):
    played_db.execute(
        "UPDATE episodes SET played=1, played_at=datetime('now') WHERE show_slug=? AND guid=?",
        (slug, guid),
    )
    played_db.commit()

def write_queue_file(slug, ep, archived):
    uri = ep["file_path"] if archived else ep["enclosure_url"]
    if not uri:
        return None
    line = _annotate_uri(ep["runlength"], ep["title"], uri)
    out = PLAYLISTS_DIR / f"{slug}.txt"
    out.write_text(line + "\n")
    return out

def update_all():
    subs_db = open_subs_db()
    played_db = open_played_db()
    shows = subs_db.execute("SELECT slug, name, archived FROM shows ORDER BY name").fetchall()
    updated = 0
    for show in shows:
        slug = show["slug"]
        archived = show["archived"] == 1
        ep = select_next_episode(slug, played_db)
        if ep is None:
            continue
        out = write_queue_file(slug, ep, archived)
        if out is None:
            log.warning("No playable URI for %s (%s); skipping.", show["name"], slug)
            continue
        mark_as_played(slug, ep["guid"], played_db)
        updated += 1
        log.info("Queued %s: %s -> %s", slug, ep["title"], out.name)
    subs_db.close()
    played_db.close()
    log.info("=== Update complete: %d show(s) queued ===", updated)

def json_summary():
    subs_db = open_subs_db()
    played_db = open_played_db()
    shows = subs_db.execute("SELECT slug, name FROM shows ORDER BY name").fetchall()
    result = {}
    for show in shows:
        slug = show["slug"]
        counts = played_db.execute(
            "SELECT COUNT(*) AS total, SUM(CASE WHEN played=0 THEN 1 ELSE 0 END) AS unplayed "
            "FROM episodes WHERE show_slug=?",
            (slug,),
        ).fetchone()
        total = counts["total"] or 0
        unplayed = counts["unplayed"] or 0
        result[slug] = {"name": show["name"], "total": total, "unplayed": unplayed, "played": total - unplayed}
    subs_db.close()
    played_db.close()
    print(json.dumps(result, indent=2))

def main():
    parser = argparse.ArgumentParser(description="Playlist updater for radio automation")
    parser.add_argument("--json", action="store_true", help="Emit JSON summary and exit")
    args = parser.parse_args()

    init_paths()
    STATE_DIR.mkdir(parents=True, exist_ok=True)
    LOGS_DIR.mkdir(parents=True, exist_ok=True)
    PLAYLISTS_DIR.mkdir(parents=True, exist_ok=True)
    _setup_logging()

    needs_lock = not args.json

    if needs_lock and not acquire_lock():
        log.info("Another radio process holds the lock; skipping this run.")
        return

    try:
        if args.json:
            json_summary()
        else:
            update_all()
    finally:
        if needs_lock:
            release_lock()

if __name__ == "__main__":
    main()