# backend/database.py
import sqlite3
import bcrypt
import os
import time

DATABASE_PATH = 'data.db'

def get_db_connection():
    """Establishes a connection to the SQLite database."""
    conn = sqlite3.connect(DATABASE_PATH)
    return conn

def init_db():
    """
    Initializes the database by creating the necessary tables.
    This function should be called once on application startup.
    """
    conn = get_db_connection()
    c = conn.cursor()
    
    c.execute("""
        CREATE TABLE IF NOT EXISTS users (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            username TEXT UNIQUE NOT NULL,
            password_hash TEXT NOT NULL
        )
    """)
    
    c.execute("""
        CREATE TABLE IF NOT EXISTS projects (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            user_id INTEGER NOT NULL,
            title TEXT NOT NULL,
            prompt TEXT NOT NULL,
            status TEXT NOT NULL,
            created_at INTEGER NOT NULL,
            logs TEXT,
            zip_path TEXT,
            FOREIGN KEY (user_id) REFERENCES users (id)
        )
    """)
    
    conn.commit()
    conn.close()

def create_user(username, password):
    """
    Creates a new user in the database.
    Returns the user ID or None if the username is already taken.
    """
    conn = get_db_connection()
    c = conn.cursor()
    
    hashed_password = bcrypt.hashpw(password.encode('utf-8'), bcrypt.gensalt()).decode('utf-8')
    
    try:
        c.execute("INSERT INTO users (username, password_hash) VALUES (?, ?)", (username, hashed_password))
        conn.commit()
        return c.lastrowid
    except sqlite3.IntegrityError:
        return None
    finally:
        conn.close()

def get_user_by_username(username):
    """Fetches a user by their username."""
    conn = get_db_connection()
    c = conn.cursor()
    c.execute("SELECT * FROM users WHERE username = ?", (username,))
    user = c.fetchone()
    conn.close()
    
    if user:
        columns = [desc[0] for desc in c.description]
        return dict(zip(columns, user))
    
    return None

def verify_password(password, password_hash):
    """Verifies a password against its hash."""
    return bcrypt.checkpw(password.encode('utf-8'), password_hash.encode('utf-8'))

def create_project(user_id, title, prompt):
    """Creates a new project record and returns its ID."""
    conn = get_db_connection()
    c = conn.cursor()
    c.execute("INSERT INTO projects (user_id, title, prompt, status, created_at) VALUES (?, ?, ?, ?, ?)",
              (user_id, title, prompt, "queued", int(time.time())))
    project_id = c.lastrowid
    conn.commit()
    conn.close()
    return project_id

def get_user_projects(user_id):
    """Retrieves all projects for a given user, ordered by creation date."""
    conn = get_db_connection()
    c = conn.cursor()
    c.execute("SELECT * FROM projects WHERE user_id = ? ORDER BY created_at DESC", (user_id,))
    projects = c.fetchall()
    conn.close()
    
    project_list = []
    if projects:
        columns = [desc[0] for desc in c.description]
        for project in projects:
            project_list.append(dict(zip(columns, project)))
    
    return project_list

def get_project(project_id):
    """
    Fetches a single project record by its unique ID.
    This function is used by the front end for live log updates.
    """
    conn = get_db_connection()
    c = conn.cursor()
    c.execute("SELECT * FROM projects WHERE id = ?", (project_id,))
    project = c.fetchone()
    conn.close()
    
    if project:
        columns = [desc[0] for desc in c.description]
        return dict(zip(columns, project))
    
    return None

def update_project_status(project_id, status, logs=None, zip_path=None):
    """Updates the status and optional logs/zip path for a project."""
    conn = get_db_connection()
    c = conn.cursor()
    
    if logs is not None and zip_path is not None:
        c.execute("UPDATE projects SET status = ?, logs = ?, zip_path = ? WHERE id = ?", (status, logs, zip_path, project_id))
    elif logs is not None:
        c.execute("UPDATE projects SET status = ?, logs = ? WHERE id = ?", (status, logs, project_id))
    else:
        c.execute("UPDATE projects SET status = ? WHERE id = ?", (status, project_id))
        
    conn.commit()
    conn.close()