import threading
from datetime import datetime, timezone
from uuid import uuid4

from psycopg2.extras import Json

from app.services.db import run_with_retry

_DEFAULT_USER_ID = None
_DEFAULT_LOCK = threading.Lock()


def _utc_now():
    return datetime.now(timezone.utc)


def get_default_user_id():
    global _DEFAULT_USER_ID
    if _DEFAULT_USER_ID:
        return _DEFAULT_USER_ID

    def _op(cur, _conn):
        cur.execute("SELECT id FROM app_user ORDER BY username LIMIT 1")
        row = cur.fetchone()
        return row[0] if row else None

    user_id = run_with_retry(_op)
    if user_id:
        with _DEFAULT_LOCK:
            _DEFAULT_USER_ID = user_id
    return user_id


def _default_run_id(user_id: str) -> str:
    return f"default_{user_id}"


def ensure_default_run(user_id: str):
    run_id = _default_run_id(user_id)

    def _op(cur, _conn):
        now = _utc_now()
        cur.execute(
            """
            INSERT INTO strategy_run (
                run_id, user_id, created_at, started_at, stopped_at, status, strategy, mode, broker, meta
            )
            VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s, %s)
            ON CONFLICT (run_id) DO NOTHING
            """,
            (
                run_id,
                user_id,
                now,
                None,
                None,
                "STOPPED",
                None,
                None,
                None,
                Json({}),
            ),
        )
        return run_id

    return run_with_retry(_op)


def get_active_run_id(user_id: str):
    def _op(cur, _conn):
        cur.execute(
            """
            SELECT run_id
            FROM strategy_run
            WHERE user_id = %s AND status = 'RUNNING'
            ORDER BY created_at DESC
            LIMIT 1
            """,
            (user_id,),
        )
        row = cur.fetchone()
        if row:
            return row[0]
        cur.execute(
            """
            SELECT run_id
            FROM strategy_run
            WHERE user_id = %s
            ORDER BY created_at DESC
            LIMIT 1
            """,
            (user_id,),
        )
        row = cur.fetchone()
        if row:
            return row[0]
        return None

    run_id = run_with_retry(_op)
    if run_id:
        return run_id
    return ensure_default_run(user_id)


def get_running_run_id(user_id: str):
    def _op(cur, _conn):
        cur.execute(
            """
            SELECT run_id
            FROM strategy_run
            WHERE user_id = %s AND status = 'RUNNING'
            ORDER BY created_at DESC
            LIMIT 1
            """,
            (user_id,),
        )
        row = cur.fetchone()
        return row[0] if row else None

    return run_with_retry(_op)


def create_strategy_run(user_id: str, strategy: str | None, mode: str | None, broker: str | None, meta: dict | None):
    run_id = str(uuid4())

    def _op(cur, _conn):
        now = _utc_now()
        cur.execute(
            """
            INSERT INTO strategy_run (
                run_id, user_id, created_at, started_at, stopped_at, status, strategy, mode, broker, meta
            )
            VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s, %s)
            """,
            (
                run_id,
                user_id,
                now,
                now,
                None,
                "RUNNING",
                strategy,
                mode,
                broker,
                Json(meta or {}),
            ),
        )
        return run_id

    return run_with_retry(_op)


def update_run_status(user_id: str, run_id: str, status: str, meta: dict | None = None):
    def _op(cur, _conn):
        now = _utc_now()
        if status == "RUNNING":
            cur.execute(
                """
                UPDATE strategy_run
                SET status = %s, started_at = COALESCE(started_at, %s), meta = COALESCE(meta, '{}'::jsonb) || %s
                WHERE run_id = %s AND user_id = %s
                """,
                (status, now, Json(meta or {}), run_id, user_id),
            )
        else:
            cur.execute(
                """
                UPDATE strategy_run
                SET status = %s, stopped_at = %s, meta = COALESCE(meta, '{}'::jsonb) || %s
                WHERE run_id = %s AND user_id = %s
                """,
                (status, now, Json(meta or {}), run_id, user_id),
            )
        return True

    return run_with_retry(_op)