"""
ScanLook Module Manager
Handles module discovery, installation, uninstallation, and activation
"""

import os
import json
import sqlite3
import importlib.util
from pathlib import Path
from typing import List, Dict, Optional


MODULES_DIR = Path(__file__).parent / 'modules'
DB_PATH = Path(__file__).parent / 'database' / 'scanlook.db'


def get_db():
    """Get database connection (standalone, no Flask context needed)"""
    conn = sqlite3.connect(str(DB_PATH))
    conn.row_factory = sqlite3.Row
    return conn


def query_db(query, args=(), one=False):
    """Query database and return results"""
    conn = get_db()
    cur = conn.execute(query, args)
    rv = cur.fetchall()
    conn.close()
    return (rv[0] if rv else None) if one else rv


def execute_db(query, args=()):
    """Execute database command and return lastrowid"""
    conn = get_db()
    cur = conn.execute(query, args)
    conn.commit()
    last_id = cur.lastrowid
    conn.close()
    return last_id


class ModuleManager:
    """Manages ScanLook modules"""
    
    def __init__(self):
        self.modules_dir = MODULES_DIR
        self._ensure_modules_table()
    
    def _ensure_modules_table(self):
        """Ensure the module_registry table exists in the database"""
        conn = get_db()
        conn.execute('''
            CREATE TABLE IF NOT EXISTS module_registry (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                module_key TEXT UNIQUE NOT NULL,
                name TEXT NOT NULL,
                version TEXT NOT NULL,
                author TEXT,
                description TEXT,
                is_installed INTEGER DEFAULT 0,
                is_active INTEGER DEFAULT 0,
                installed_at TEXT,
                config_json TEXT
            )
        ''')
        conn.commit()
        conn.close()
    
    def scan_available_modules(self) -> List[Dict]:
        """
        Scan the /modules directory for available modules.
        Returns list of module info dicts from manifest.json files.
        """
        available = []
        
        if not self.modules_dir.exists():
            return available
        
        for item in self.modules_dir.iterdir():
            if not item.is_dir():
                continue
            
            manifest_path = item / 'manifest.json'
            if not manifest_path.exists():
                continue
            
            try:
                with open(manifest_path, 'r') as f:
                    manifest = json.load(f)
                
                # Validate required fields
                required = ['module_key', 'name', 'version', 'author', 'description']
                if not all(field in manifest for field in required):
                    print(f"⚠️  Invalid manifest in {item.name}: missing required fields")
                    continue
                
                # Check installation status from database
                db_module = query_db(
                    'SELECT is_installed, is_active FROM module_registry WHERE module_key = ?',
                    [manifest['module_key']],
                    one=True
                )
                
                manifest['is_installed'] = db_module['is_installed'] if db_module else False
                manifest['is_active'] = db_module['is_active'] if db_module else False
                manifest['path'] = str(item)
                
                available.append(manifest)
            
            except json.JSONDecodeError as e:
                print(f"⚠️  Invalid JSON in {manifest_path}: {e}")
                continue
            except Exception as e:
                print(f"⚠️  Error reading manifest from {item.name}: {e}")
                continue
        
        return sorted(available, key=lambda x: x['name'])
    
    def get_module_by_key(self, module_key: str) -> Optional[Dict]:
        """Get module info by module_key"""
        modules = self.scan_available_modules()
        for module in modules:
            if module['module_key'] == module_key:
                return module
        return None
    
    def install_module(self, module_key: str) -> Dict:
        """
        Install a module:
        1. Load manifest
        2. Run migrations (create tables)
        3. Register in database
        4. Set is_installed=1, is_active=1
        
        Returns: {'success': bool, 'message': str}
        """
        try:
            # Get module info
            module = self.get_module_by_key(module_key)
            if not module:
                return {'success': False, 'message': f'Module {module_key} not found'}
            
            # Check if already installed
            if module['is_installed']:
                return {'success': False, 'message': f'Module {module_key} is already installed'}
            
            # Load module's migrations
            migrations_path = Path(module['path']) / 'migrations.py'
            if not migrations_path.exists():
                return {'success': False, 'message': 'Module is missing migrations.py'}
            
            # Import migrations module
            spec = importlib.util.spec_from_file_location(f"{module_key}_migrations", migrations_path)
            migrations_module = importlib.util.module_from_spec(spec)
            spec.loader.exec_module(migrations_module)
            
            # Run schema installation
            print(f"\n📦 Installing module: {module['name']}")
            
            conn = get_db()
            
            # Execute schema SQL
            if hasattr(migrations_module, 'get_schema'):
                schema_sql = migrations_module.get_schema()
                conn.executescript(schema_sql)
                print(f"  ✅ Database schema created")
            
            # Run module-specific migrations
            if hasattr(migrations_module, 'get_migrations'):
                migrations = migrations_module.get_migrations()
                for version, name, func in migrations:
                    print(f"  Running migration {version}: {name}")
                    func(conn)
            
            conn.commit()
            
            # Register module in database
            existing = query_db('SELECT id FROM module_registry WHERE module_key = ?', [module_key], one=True)
            
            if existing:
                execute_db('''
                    UPDATE module_registry 
                    SET name = ?, version = ?, author = ?, description = ?,
                        is_installed = 1, is_active = 1, installed_at = CURRENT_TIMESTAMP
                    WHERE module_key = ?
                ''', [module['name'], module['version'], module['author'], 
                      module['description'], module_key])
            else:
                execute_db('''
                    INSERT INTO module_registry (module_key, name, version, author, description, 
                                        is_installed, is_active, installed_at)
                    VALUES (?, ?, ?, ?, ?, 1, 1, CURRENT_TIMESTAMP)
                ''', [module_key, module['name'], module['version'], 
                      module['author'], module['description']])
            
            # Also register in old Modules table for compatibility
            old_module = query_db('SELECT module_id FROM Modules WHERE module_key = ?', [module_key], one=True)
            if not old_module:
                execute_db('''
                    INSERT INTO Modules (module_name, module_key, description, is_active)
                    VALUES (?, ?, ?, 1)
                ''', [module['name'], module_key, module['description']])
            
            conn.close()
            
            print(f"✅ Module {module['name']} installed successfully")
            return {'success': True, 'message': f'Module {module["name"]} installed successfully'}
        
        except Exception as e:
            print(f"❌ Installation failed: {e}")
            import traceback
            traceback.print_exc()
            return {'success': False, 'message': f'Installation failed: {str(e)}'}
    
    def uninstall_module(self, module_key: str, drop_tables: bool = True) -> Dict:
        """
        Uninstall a module:
        1. Set is_installed=0, is_active=0 in database
        2. Optionally drop all module tables
        3. Remove from old Modules table
        
        Returns: {'success': bool, 'message': str}
        """
        try:
            module = self.get_module_by_key(module_key)
            if not module:
                return {'success': False, 'message': f'Module {module_key} not found'}
            
            if not module['is_installed']:
                return {'success': False, 'message': f'Module {module_key} is not installed'}
            
            print(f"\n🗑️  Uninstalling module: {module['name']}")
            
            conn = get_db()
            
            # Drop tables if requested
            if drop_tables:
                print(f"  Dropping database tables...")
                # Load migrations to get table names
                migrations_path = Path(module['path']) / 'migrations.py'
                if migrations_path.exists():
                    spec = importlib.util.spec_from_file_location(f"{module_key}_migrations", migrations_path)
                    migrations_module = importlib.util.module_from_spec(spec)
                    spec.loader.exec_module(migrations_module)
                    
                    # Get schema and extract table names
                    if hasattr(migrations_module, 'get_schema'):
                        schema = migrations_module.get_schema()
                        # Simple regex to find CREATE TABLE statements
                        import re
                        tables = re.findall(r'CREATE TABLE IF NOT EXISTS (\w+)', schema)
                        
                        for table in tables:
                            try:
                                conn.execute(f'DROP TABLE IF EXISTS {table}')
                                print(f"    Dropped table: {table}")
                            except Exception as e:
                                print(f"    Warning: Could not drop {table}: {e}")
            
            # Update module_registry table
            execute_db('''
                UPDATE module_registry 
                SET is_installed = 0, is_active = 0
                WHERE module_key = ?
            ''', [module_key])
            
            # Remove from old Modules table
            execute_db('DELETE FROM Modules WHERE module_key = ?', [module_key])
            
            # Remove user module assignments
            old_module_id = query_db('SELECT module_id FROM Modules WHERE module_key = ?', [module_key], one=True)
            if old_module_id:
                execute_db('DELETE FROM UserModules WHERE module_id = ?', [old_module_id['module_id']])
            
            conn.commit()
            conn.close()
            
            print(f"✅ Module {module['name']} uninstalled successfully")
            return {'success': True, 'message': f'Module {module["name"]} uninstalled successfully'}
        
        except Exception as e:
            print(f"❌ Uninstallation failed: {e}")
            return {'success': False, 'message': f'Uninstallation failed: {str(e)}'}
    
    def activate_module(self, module_key: str) -> Dict:
        """Activate an installed module"""
        module = self.get_module_by_key(module_key)
        if not module:
            return {'success': False, 'message': f'Module {module_key} not found'}
        
        if not module['is_installed']:
            return {'success': False, 'message': 'Module must be installed first'}
        
        execute_db('UPDATE module_registry SET is_active = 1 WHERE module_key = ?', [module_key])
        execute_db('UPDATE Modules SET is_active = 1 WHERE module_key = ?', [module_key])
        
        return {'success': True, 'message': f'Module {module["name"]} activated'}
    
    def deactivate_module(self, module_key: str) -> Dict:
        """Deactivate a module (keeps it installed)"""
        module = self.get_module_by_key(module_key)
        if not module:
            return {'success': False, 'message': f'Module {module_key} not found'}
        
        execute_db('UPDATE module_registry SET is_active = 0 WHERE module_key = ?', [module_key])
        execute_db('UPDATE Modules SET is_active = 0 WHERE module_key = ?', [module_key])
        
        return {'success': True, 'message': f'Module {module["name"]} deactivated'}
    
    def load_active_modules(self, app):
        """
        Load all active modules and register their blueprints with Flask app.
        Called during app startup.
        """
        modules = self.scan_available_modules()
        active_modules = [m for m in modules if m['is_installed'] and m['is_active']]
        
        print(f"\n🔌 Loading {len(active_modules)} active module(s)...")
        
        for module in active_modules:
            try:
                # Import module's __init__.py
                init_path = Path(module['path']) / '__init__.py'
                if not init_path.exists():
                    print(f"  ⚠️  {module['name']}: Missing __init__.py")
                    continue
                
                spec = importlib.util.spec_from_file_location(
                    f"modules.{module['module_key']}", 
                    init_path
                )
                module_package = importlib.util.module_from_spec(spec)
                spec.loader.exec_module(module_package)
                
                # Get blueprint from create_blueprint()
                if hasattr(module_package, 'create_blueprint'):
                    blueprint = module_package.create_blueprint()
                    app.register_blueprint(blueprint)
                    print(f"  ✅ {module['name']} loaded at {module.get('routes_prefix', '/unknown')}")
                else:
                    print(f"  ⚠️  {module['name']}: Missing create_blueprint() function")
            
            except Exception as e:
                print(f"  ❌ Failed to load {module['name']}: {e}")
                import traceback
                traceback.print_exc()
        
        print("✅ Module loading complete\n")


# Global instance
manager = ModuleManager()


def get_module_manager() -> ModuleManager:
    """Get the global module manager instance"""
    return manager