import os
import secrets
import logging
from datetime import datetime, timedelta, timezone

import aiosqlite

from app.email import send_magic_link

logger = logging.getLogger(__name__)

SITE_URL = os.getenv("SITE_URL", "http://localhost:8000")
ENV = os.getenv("ENV", "development")
TOKEN_TTL_MINUTES = 15
SESSION_TTL_DAYS = 30


def _now() -> str:
    return datetime.now(timezone.utc).isoformat()


def _in(minutes: int = 0, days: int = 0) -> str:
    delta = timedelta(minutes=minutes, days=days)
    return (datetime.now(timezone.utc) + delta).isoformat()


def _expired(iso: str) -> bool:
    return datetime.now(timezone.utc) > datetime.fromisoformat(iso)


async def create_magic_token(email: str, db: aiosqlite.Connection) -> str:
    # Clean up old unused tokens for this email
    await db.execute(
        "DELETE FROM magic_link_tokens WHERE email = ? AND used_at IS NULL",
        (email,),
    )

    token_id = secrets.token_urlsafe(16)
    token = secrets.token_urlsafe(32)
    expires_at = _in(minutes=TOKEN_TTL_MINUTES)

    await db.execute(
        "INSERT INTO magic_link_tokens (id, email, token, expires_at) VALUES (?, ?, ?, ?)",
        (token_id, email, token, expires_at),
    )
    await db.commit()

    link = f"{SITE_URL}/auth/verify?token={token}"
    await send_magic_link(email, link)
    return token


async def verify_magic_token(token: str, db: aiosqlite.Connection):
    """Returns the email if token is valid and unused, else None."""
    async with db.execute(
        "SELECT email, expires_at, used_at FROM magic_link_tokens WHERE token = ?",
        (token,),
    ) as cursor:
        row = await cursor.fetchone()

    if row is None:
        return None
    if row["used_at"] is not None:
        return None
    if _expired(row["expires_at"]):
        return None

    # Mark token as used
    await db.execute(
        "UPDATE magic_link_tokens SET used_at = ? WHERE token = ?",
        (_now(), token),
    )
    await db.commit()

    return row["email"]


async def create_session(user_id: str, db: aiosqlite.Connection) -> str:
    session_id = secrets.token_urlsafe(16)
    token = secrets.token_urlsafe(32)
    expires_at = _in(days=SESSION_TTL_DAYS)

    await db.execute(
        "INSERT INTO sessions (id, user_id, token, expires_at, created_at) VALUES (?, ?, ?, ?, ?)",
        (session_id, user_id, token, expires_at, _now()),
    )
    await db.commit()
    return token


async def delete_session(token: str, db: aiosqlite.Connection):
    await db.execute("DELETE FROM sessions WHERE token = ?", (token,))
    await db.commit()