from sqlalchemy import text
from sqlalchemy.ext.asyncio import create_async_engine, AsyncSession, async_sessionmaker
from sqlalchemy.orm import DeclarativeBase
from app.config import settings
import os

os.makedirs(settings.DATA_DIR, exist_ok=True)

engine = create_async_engine(
    settings.DATABASE_URL,
    echo=settings.DEBUG,
    pool_pre_ping=True,
)

async_session = async_sessionmaker(
    engine,
    class_=AsyncSession,
    expire_on_commit=False,
)


class Base(DeclarativeBase):
    pass


async def get_db() -> AsyncSession:
    async with async_session() as session:
        try:
            yield session
        finally:
            await session.close()


async def init_db():
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)
        await ensure_log_columns(conn)
        await ensure_message_columns(conn)
        await ensure_document_columns(conn)


async def ensure_log_columns(conn):
    result = await conn.execute(text("PRAGMA table_info(logs)"))
    rows = result.fetchall()
    if not rows:
        return

    columns = {row[1] for row in rows}
    required_columns = {
        "request_id": "ALTER TABLE logs ADD COLUMN request_id VARCHAR(64)",
        "route": "ALTER TABLE logs ADD COLUMN route VARCHAR(255)",
        "method": "ALTER TABLE logs ADD COLUMN method VARCHAR(16)",
        "status_code": "ALTER TABLE logs ADD COLUMN status_code INTEGER",
        "error_type": "ALTER TABLE logs ADD COLUMN error_type VARCHAR(100)",
        "operation": "ALTER TABLE logs ADD COLUMN operation VARCHAR(100)",
    }
    for column, ddl in required_columns.items():
        if column not in columns:
            await conn.execute(text(ddl))


async def ensure_message_columns(conn):
    result = await conn.execute(text("PRAGMA table_info(messages)"))
    rows = result.fetchall()
    if not rows:
        return

    columns = {row[1] for row in rows}
    required_columns = {
        "attachments": "ALTER TABLE messages ADD COLUMN attachments JSON",
    }
    for column, ddl in required_columns.items():
        if column not in columns:
            await conn.execute(text(ddl))


async def ensure_document_columns(conn):
    result = await conn.execute(text("PRAGMA table_info(documents)"))
    rows = result.fetchall()
    if not rows:
        return

    columns = {row[1] for row in rows}
    required_columns = {
        "ingestion_status": "ALTER TABLE documents ADD COLUMN ingestion_status VARCHAR(50) DEFAULT 'uploaded' NOT NULL",
        "ingestion_error": "ALTER TABLE documents ADD COLUMN ingestion_error TEXT",
        "indexed_at": "ALTER TABLE documents ADD COLUMN indexed_at DATETIME",
        "parser_version": "ALTER TABLE documents ADD COLUMN parser_version VARCHAR(50)",
        "index_version": "ALTER TABLE documents ADD COLUMN index_version VARCHAR(50)",
        "normalized_content": "ALTER TABLE documents ADD COLUMN normalized_content TEXT",
        "normalized_format": "ALTER TABLE documents ADD COLUMN normalized_format VARCHAR(50)",
    }
    for column, ddl in required_columns.items():
        if column not in columns:
            await conn.execute(text(ddl))