"""
Database initialization script for AI Service.
Run this script to create the database and all required tables.

Usage:
    python scripts/init_db.py [--create-db]

Options:
    --create-db    Create the database if it doesn't exist
"""

import asyncio
import argparse
from sqlalchemy.ext.asyncio import create_async_engine
from sqlalchemy import text

from app.core.config import get_settings


CREATE_TABLES_SQL = [
    """
    CREATE TABLE IF NOT EXISTS chat_sessions (
        id UUID NOT NULL PRIMARY KEY,
        tenant_id VARCHAR NOT NULL,
        session_id VARCHAR NOT NULL,
        channel_type VARCHAR,
        metadata JSON,
        created_at TIMESTAMP WITHOUT TIME ZONE NOT NULL,
        updated_at TIMESTAMP WITHOUT TIME ZONE NOT NULL
    )
    """,
    """
    CREATE TABLE IF NOT EXISTS chat_messages (
        id UUID NOT NULL PRIMARY KEY,
        tenant_id VARCHAR NOT NULL,
        session_id VARCHAR NOT NULL,
        role VARCHAR NOT NULL,
        content TEXT NOT NULL,
        created_at TIMESTAMP WITHOUT TIME ZONE NOT NULL
    )
    """,
    """
    CREATE TABLE IF NOT EXISTS knowledge_bases (
        id UUID NOT NULL PRIMARY KEY,
        tenant_id VARCHAR NOT NULL,
        name VARCHAR NOT NULL,
        description VARCHAR,
        created_at TIMESTAMP WITHOUT TIME ZONE NOT NULL,
        updated_at TIMESTAMP WITHOUT TIME ZONE NOT NULL
    )
    """,
    """
    CREATE TABLE IF NOT EXISTS documents (
        id UUID NOT NULL PRIMARY KEY,
        tenant_id VARCHAR NOT NULL,
        kb_id VARCHAR NOT NULL,
        file_name VARCHAR NOT NULL,
        file_path VARCHAR,
        file_size INTEGER,
        file_type VARCHAR,
        status VARCHAR NOT NULL DEFAULT 'pending',
        error_msg VARCHAR,
        created_at TIMESTAMP WITHOUT TIME ZONE NOT NULL,
        updated_at TIMESTAMP WITHOUT TIME ZONE NOT NULL
    )
    """,
    """
    CREATE TABLE IF NOT EXISTS index_jobs (
        id UUID NOT NULL PRIMARY KEY,
        tenant_id VARCHAR NOT NULL,
        doc_id UUID NOT NULL,
        status VARCHAR NOT NULL DEFAULT 'pending',
        progress INTEGER NOT NULL DEFAULT 0,
        error_msg VARCHAR,
        created_at TIMESTAMP WITHOUT TIME ZONE NOT NULL,
        updated_at TIMESTAMP WITHOUT TIME ZONE NOT NULL
    )
    """,
]

CREATE_INDEXES_SQL = [
    "CREATE INDEX IF NOT EXISTS ix_chat_sessions_tenant_id ON chat_sessions (tenant_id)",
    "CREATE UNIQUE INDEX IF NOT EXISTS ix_chat_sessions_tenant_session ON chat_sessions (tenant_id, session_id)",
    "CREATE INDEX IF NOT EXISTS ix_chat_messages_tenant_id ON chat_messages (tenant_id)",
    "CREATE INDEX IF NOT EXISTS ix_chat_messages_tenant_session ON chat_messages (tenant_id, session_id)",
    "CREATE INDEX IF NOT EXISTS ix_chat_messages_tenant_session_created ON chat_messages (tenant_id, session_id, created_at)",
    "CREATE INDEX IF NOT EXISTS ix_knowledge_bases_tenant_id ON knowledge_bases (tenant_id)",
    "CREATE INDEX IF NOT EXISTS ix_documents_tenant_id ON documents (tenant_id)",
    "CREATE INDEX IF NOT EXISTS ix_documents_tenant_kb ON documents (tenant_id, kb_id)",
    "CREATE INDEX IF NOT EXISTS ix_documents_tenant_status ON documents (tenant_id, status)",
    "CREATE INDEX IF NOT EXISTS ix_index_jobs_tenant_id ON index_jobs (tenant_id)",
    "CREATE INDEX IF NOT EXISTS ix_index_jobs_tenant_doc ON index_jobs (tenant_id, doc_id)",
    "CREATE INDEX IF NOT EXISTS ix_index_jobs_tenant_status ON index_jobs (tenant_id, status)",
]


async def create_database_if_not_exists(settings):
    """Create database if it doesn't exist."""
    db_url = settings.database_url
    postgres_url = db_url.rsplit("/", 1)[0] + "/postgres"
    
    engine = create_async_engine(
        postgres_url,
        isolation_level="AUTOCOMMIT",
        pool_size=1,
    )
    
    db_name = db_url.rsplit("/", 1)[-1].split("?")[0]
    
    try:
        async with engine.connect() as conn:
            result = await conn.execute(
                text(f"SELECT datname FROM pg_database WHERE datname = '{db_name}'")
            )
            exists = result.fetchone()
            
            if not exists:
                print(f"Creating database '{db_name}'...")
                await conn.execute(text(f'CREATE DATABASE "{db_name}"'))
                print(f"Database '{db_name}' created successfully!")
            else:
                print(f"Database '{db_name}' already exists.")
    except Exception as e:
        print(f"Error creating database: {e}")
        raise
    finally:
        await engine.dispose()


async def create_tables(settings):
    """Create all tables (idempotent)."""
    engine = create_async_engine(settings.database_url)
    
    try:
        async with engine.begin() as conn:
            for stmt in CREATE_TABLES_SQL:
                await conn.execute(text(stmt.strip()))
            
            for stmt in CREATE_INDEXES_SQL:
                try:
                    await conn.execute(text(stmt))
                except Exception as e:
                    if "already exists" in str(e).lower() or "已经存在" in str(e):
                        continue
                    raise
        
        print("Tables and indexes created/verified successfully!")
        
        async with engine.connect() as conn:
            result = await conn.execute(
                text("SELECT tablename FROM pg_tables WHERE schemaname = 'public' ORDER BY tablename")
            )
            tables = [row[0] for row in result]
            print(f"Tables in database: {tables}")
    except Exception as e:
        print(f"Error creating tables: {e}")
        raise
    finally:
        await engine.dispose()


async def main():
    parser = argparse.ArgumentParser(description="Initialize AI Service database")
    parser.add_argument("--create-db", action="store_true", help="Create database if it doesn't exist")
    args = parser.parse_args()
    
    settings = get_settings()
    print(f"Database URL: {settings.database_url.split('@')[1] if '@' in settings.database_url else settings.database_url}")
    
    if args.create_db:
        await create_database_if_not_exists(settings)
    
    await create_tables(settings)
    print("\nDatabase initialization complete!")


if __name__ == "__main__":
    asyncio.run(main())