from sqlalchemy import create_engine, text
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
import os

from app.config import settings

DATABASE_URL = settings.database_url or os.getenv("DATABASE_URL", "sqlite:///./amazon_intel.db")

if DATABASE_URL.startswith("sqlite"):
    engine = create_engine(DATABASE_URL, connect_args={"check_same_thread": False})
else:
    engine = create_engine(DATABASE_URL, pool_pre_ping=True, pool_recycle=300)

SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
Base = declarative_base()


def migrate_schema():
    """Add columns when schema evolves (SQLite + PostgreSQL)."""
    user_alters_sqlite = [
        "ALTER TABLE users ADD COLUMN token_version INTEGER DEFAULT 0",
        "ALTER TABLE users ADD COLUMN auth_provider VARCHAR(20) DEFAULT 'email'",
        "ALTER TABLE users ADD COLUMN firebase_uid VARCHAR(128)",
    ]
    user_alters_pg = [
        "ALTER TABLE users ADD COLUMN IF NOT EXISTS token_version INTEGER DEFAULT 0",
        "ALTER TABLE users ADD COLUMN IF NOT EXISTS auth_provider VARCHAR(20) DEFAULT 'email'",
        "ALTER TABLE users ADD COLUMN IF NOT EXISTS firebase_uid VARCHAR(128)",
    ]
    sqlite_product_alters = [
        "ALTER TABLE products ADD COLUMN seller_count INTEGER",
        "ALTER TABLE products ADD COLUMN buy_box_winner VARCHAR(255)",
        "ALTER TABLE products ADD COLUMN buy_box_price NUMERIC(10,2)",
        "ALTER TABLE products ADD COLUMN buy_box_is_fba BOOLEAN DEFAULT 1",
        "ALTER TABLE products ADD COLUMN is_amazon_sold BOOLEAN DEFAULT 0",
        "ALTER TABLE products ADD COLUMN last_data_source VARCHAR(20) DEFAULT 'cached'",
        "ALTER TABLE products ADD COLUMN upc VARCHAR(20)",
        "ALTER TABLE products ADD COLUMN has_buy_box BOOLEAN DEFAULT 1",
        "ALTER TABLE products ADD COLUMN package_weight_lbs NUMERIC(8,3)",
        "ALTER TABLE products ADD COLUMN other_sellers_json TEXT",
        "ALTER TABLE products ADD COLUMN offers_source VARCHAR(30)",
        "ALTER TABLE products ADD COLUMN marketplace VARCHAR(8) DEFAULT 'us'",
        "ALTER TABLE products ADD COLUMN currency VARCHAR(8) DEFAULT 'USD'",
    ]
    pg_product_alters = [
        "ALTER TABLE products ADD COLUMN IF NOT EXISTS upc VARCHAR(20)",
        "ALTER TABLE products ADD COLUMN IF NOT EXISTS has_buy_box BOOLEAN DEFAULT TRUE",
        "ALTER TABLE products ADD COLUMN IF NOT EXISTS package_weight_lbs NUMERIC(8,3)",
        "ALTER TABLE products ADD COLUMN IF NOT EXISTS other_sellers_json TEXT",
        "ALTER TABLE products ADD COLUMN IF NOT EXISTS offers_source VARCHAR(30)",
        "ALTER TABLE products ADD COLUMN IF NOT EXISTS marketplace VARCHAR(8) DEFAULT 'us'",
        "ALTER TABLE products ADD COLUMN IF NOT EXISTS currency VARCHAR(8) DEFAULT 'USD'",
    ]
    is_pg = DATABASE_URL.startswith("postgresql")
    with engine.connect() as conn:
        for sql in (user_alters_pg if is_pg else user_alters_sqlite):
            try:
                conn.execute(text(sql))
                conn.commit()
            except Exception:
                pass
        # Google-only accounts may have no password
        if is_pg:
            try:
                conn.execute(text("ALTER TABLE users ALTER COLUMN password_hash DROP NOT NULL"))
                conn.commit()
            except Exception:
                pass
        if DATABASE_URL.startswith("sqlite"):
            for sql in sqlite_product_alters:
                try:
                    conn.execute(text(sql))
                    conn.commit()
                except Exception:
                    pass
        if is_pg:
            for sql in pg_product_alters:
                try:
                    conn.execute(text(sql))
                    conn.commit()
                except Exception:
                    pass
            # Prefer (asin, marketplace) uniqueness so US + AE can coexist
            for sql in (
                "UPDATE products SET marketplace = 'us' WHERE marketplace IS NULL",
                "UPDATE products SET currency = 'USD' WHERE currency IS NULL AND (marketplace = 'us' OR marketplace IS NULL)",
                "ALTER TABLE products DROP CONSTRAINT IF EXISTS products_asin_key",
                "ALTER TABLE products DROP CONSTRAINT IF EXISTS ix_products_asin",
                "CREATE UNIQUE INDEX IF NOT EXISTS uq_products_asin_marketplace ON products (asin, marketplace)",
            ):
                try:
                    conn.execute(text(sql))
                    conn.commit()
                except Exception:
                    pass
        else:
            for sql in (
                "UPDATE products SET marketplace = 'us' WHERE marketplace IS NULL",
                "UPDATE products SET currency = 'USD' WHERE currency IS NULL",
            ):
                try:
                    conn.execute(text(sql))
                    conn.commit()
                except Exception:
                    pass


def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()