"""Playoff bracket + per-series schedule caching.

Single table `playoff_cache` keyed by arbitrary cache_key. Stale rows are
served on fetch failure up to 24h old, with callers free to check staleness
via the returned `fetched_at` timestamp.
"""

import json
import logging
import re
import sqlite3
import time
from datetime import date, datetime
from zoneinfo import ZoneInfo

import requests

from app.config import DB_PATH

logger = logging.getLogger(__name__)

EASTERN = ZoneInfo("America/New_York")

BRACKET_TTL = 3600  # refresh at this cadence via scheduler
SERIES_TTL = 300  # lazy cache for per-series schedule fetches
MAX_STALE_SECONDS = 86400  # 24h

SERIES_ID_RE = re.compile(r"^(20\d{2})-([A-P])$")


def _connect():
    return sqlite3.connect(DB_PATH)


def create_cache_table(conn):
    conn.execute(
        """
        CREATE TABLE IF NOT EXISTS playoff_cache (
            cache_key TEXT PRIMARY KEY,
            payload TEXT NOT NULL,
            fetched_at INTEGER NOT NULL
        )
        """
    )
    conn.commit()


def _put(cache_key, payload):
    conn = _connect()
    try:
        create_cache_table(conn)
        conn.execute(
            "INSERT OR REPLACE INTO playoff_cache (cache_key, payload, fetched_at) "
            "VALUES (?, ?, ?)",
            (cache_key, json.dumps(payload), int(time.time())),
        )
        conn.commit()
    finally:
        conn.close()


def _get(cache_key):
    """Return (payload_dict, fetched_at_unix) or (None, None)."""
    conn = _connect()
    try:
        create_cache_table(conn)
        cur = conn.execute(
            "SELECT payload, fetched_at FROM playoff_cache WHERE cache_key = ?",
            (cache_key,),
        )
        row = cur.fetchone()
    finally:
        conn.close()
    if not row:
        return None, None
    return json.loads(row[0]), row[1]


# ── Bracket ────────────────────────────────────────────────────────


def bracket_key(year):
    return f"bracket:{year}"


def refresh_bracket(year=None):
    """Fetch /v1/playoff-bracket/{year} and store it. Returns payload or None."""
    if year is None:
        year = datetime.now(EASTERN).year
    url = f"https://api-web.nhle.com/v1/playoff-bracket/{year}"
    try:
        resp = requests.get(url, timeout=10)
        resp.raise_for_status()
        data = resp.json()
        _put(bracket_key(year), data)
        _maybe_record_start_date(data)
        return data
    except requests.RequestException as e:
        logger.warning("Failed to refresh playoff bracket for %s: %s", year, e)
        return None


def get_bracket(year=None):
    """Return (bracket_payload, fetched_at) from cache. Never triggers a fetch."""
    if year is None:
        year = datetime.now(EASTERN).year
    payload, fetched = _get(bracket_key(year))
    return payload, fetched


# ── Per-series schedule ────────────────────────────────────────────


def series_key(season, letter):
    return f"series:{season}:{letter.upper()}"


def parse_series_id(series_id):
    """Parse 'YYYY-L' into (season_str, letter). Returns None on invalid input."""
    m = SERIES_ID_RE.match(series_id or "")
    if not m:
        return None
    year, letter = m.group(1), m.group(2)
    season = f"{int(year) - 1}{year}"
    return season, letter


def fetch_series(series_id):
    """Fetch /v1/schedule/playoff-series/{season}/{letter}. 5-min cache.

    Returns the raw API payload or None on both cache miss and fetch failure.
    On failure we fall back to stale cache up to 24h old.
    """
    parsed = parse_series_id(series_id)
    if parsed is None:
        return None
    season, letter = parsed

    key = series_key(season, letter)
    payload, fetched = _get(key)
    if payload is not None and fetched is not None:
        if time.time() - fetched < SERIES_TTL:
            return payload

    url = (
        f"https://api-web.nhle.com/v1/schedule/playoff-series/{season}/{letter.lower()}"
    )
    try:
        resp = requests.get(url, timeout=10)
        resp.raise_for_status()
        data = resp.json()
        _put(key, data)
        return data
    except requests.RequestException as e:
        logger.warning("Failed to fetch series %s: %s", series_id, e)
        if payload is not None and fetched is not None:
            if time.time() - fetched < MAX_STALE_SECONDS:
                return payload
        return None


# ── Playoff start date (drives the "Day N" banner) ─────────────────

META_KEY = "meta:first_playoff_date"


def _maybe_record_start_date(bracket_payload):
    """Store the earliest scheduled round-1 series date as Day 1, once.

    The bracket endpoint doesn't include individual games — only the series
    list. So we record the current day as Day 1 on the first bracket fetch
    where any series has nonzero wins OR is otherwise underway. For a perfect
    Day-1 anchor we'd need the per-series schedule; the scoreboard-driven
    fallback (see record_start_date_if_missing) handles that case.
    """
    # No-op for now; the scoreboard-driven path is authoritative.
    return None


def record_start_date_if_missing(scoreboard_games, now=None):
    """Called from routes on every /scoreboard hit.

    If we haven't seen a playoff game yet and the current scoreboard contains
    one, record today (Eastern) as Day 1. Idempotent after first write.
    """
    existing, _ = _get(META_KEY)
    if existing and existing.get("first_date"):
        return existing["first_date"]

    has_playoff = any(g.get("gameType") == 3 for g in scoreboard_games)
    if not has_playoff:
        return None

    now = now or datetime.now(EASTERN)
    today = now.date().isoformat()
    _put(
        META_KEY, {"first_date": today, "recorded_at_utc": now.astimezone().isoformat()}
    )
    return today


def get_playoff_start_date():
    payload, _ = _get(META_KEY)
    if not payload or not payload.get("first_date"):
        return None
    try:
        return date.fromisoformat(payload["first_date"])
    except ValueError:
        return None


def day_n(now=None):
    """Returns (day_n, day_total_estimate) or (None, None)."""
    start = get_playoff_start_date()
    if start is None:
        return None, None
    now = now or datetime.now(EASTERN)
    today = now.date()
    n = (today - start).days + 1
    if n < 1:
        return None, None
    # Typical playoff length: ~60 days from first-round start through Cup final.
    return n, 60