import hashlib
import os
import sqlite3
from datetime import datetime

from config import get_storage_root

DB_CONN = None


def init_db():
    global DB_CONN
    DB_CONN = sqlite3.connect("fileserver.db", check_same_thread=False)
    cursor = DB_CONN.cursor()
    cursor.execute("""
        CREATE TABLE IF NOT EXISTS users (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            username TEXT UNIQUE NOT NULL,
            password_hash TEXT NOT NULL,
            quota_mb INTEGER NOT NULL,
            used_mb REAL DEFAULT 0.0
        )
    """)
    cursor.execute("""
        CREATE TABLE IF NOT EXISTS sessions (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            username TEXT NOT NULL,
            session_id TEXT UNIQUE NOT NULL,
            created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
            last_access TIMESTAMP DEFAULT CURRENT_TIMESTAMP
        )
    """)
    DB_CONN.commit()


def hash_password(password):
    return hashlib.sha256(password.encode()).hexdigest()


def get_user_quota(username):
    cursor = DB_CONN.cursor()
    cursor.execute(
        "SELECT quota_mb, used_mb FROM users WHERE username = ?", (username,)
    )
    row = cursor.fetchone()
    if row:
        return row[0], row[1]
    return None, None


def update_used_space(username, delta_mb):
    cursor = DB_CONN.cursor()
    cursor.execute(
        "UPDATE users SET used_mb = used_mb + ? WHERE username = ?",
        (delta_mb, username),
    )
    DB_CONN.commit()


def is_session_valid(session_id, session_timeout):
    cursor = DB_CONN.cursor()
    cursor.execute(
        "SELECT username, last_access FROM sessions WHERE session_id = ?", (session_id,)
    )
    row = cursor.fetchone()
    if not row:
        return None
    username, last_access = row
    now = datetime.now()
    if (now - datetime.fromisoformat(last_access)).total_seconds() > session_timeout:
        cursor.execute("DELETE FROM sessions WHERE session_id = ?", (session_id,))
        DB_CONN.commit()
        return None
    cursor.execute(
        "UPDATE sessions SET last_access = ? WHERE session_id = ?",
        (now.isoformat(), session_id),
    )
    DB_CONN.commit()
    return username


def create_session(username):
    import time

    session_id = hashlib.sha256(f"{username}{time.time()}".encode()).hexdigest()
    cursor = DB_CONN.cursor()
    cursor.execute(
        "INSERT INTO sessions (username, session_id) VALUES (?, ?)",
        (username, session_id),
    )
    DB_CONN.commit()
    return session_id


def delete_session(session_id):
    cursor = DB_CONN.cursor()
    cursor.execute("DELETE FROM sessions WHERE session_id = ?", (session_id,))
    DB_CONN.commit()


def get_user_used_space(username):
    user_dir = os.path.join(get_storage_root(), username)
    if not os.path.exists(user_dir):
        return 0.0
    total = 0
    for dirpath, dirnames, filenames in os.walk(user_dir):
        for f in filenames:
            fp = os.path.join(dirpath, f)
            total += os.path.getsize(fp)
    return total / (1024 * 1024)