from sqlalchemy import create_engine, text
from sqlalchemy.orm import sessionmaker, declarative_base

from .config import settings

connect_args = {}
if settings.database_url.startswith("sqlite"):
    connect_args["check_same_thread"] = False

engine = create_engine(settings.database_url, connect_args=connect_args)
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
Base = declarative_base()


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


def run_migrations(engine):
    """SQLite-safe migration: add new columns if they don't exist."""
    migrations = {
        "users": [
            ("email", "VARCHAR"),
            ("display_name", "VARCHAR"),
            ("avatar_url", "VARCHAR"),
            ("auth_provider", "VARCHAR DEFAULT 'local'"),
            ("google_id", "VARCHAR"),
            ("subscription_plan", "VARCHAR DEFAULT 'freemium'"),
            ("subscription_expires_at", "DATETIME"),
            ("is_admin", "BOOLEAN DEFAULT 0"),
            ("posts_generated_this_month", "INTEGER DEFAULT 0"),
            ("posts_reset_date", "DATE"),
        ],
        "characters": [("user_id", "INTEGER")],
        "posts": [("user_id", "INTEGER")],
        "affiliate_links": [("user_id", "INTEGER")],
        "editorial_plans": [("user_id", "INTEGER")],
        "social_accounts": [("user_id", "INTEGER")],
        "system_settings": [("user_id", "INTEGER")],
    }
    with engine.connect() as conn:
        for table, cols in migrations.items():
            try:
                existing = {row[1] for row in conn.execute(text(f"PRAGMA table_info({table})"))}
                for col_name, col_def in cols:
                    if col_name not in existing:
                        conn.execute(text(f"ALTER TABLE {table} ADD COLUMN {col_name} {col_def}"))
                conn.commit()
            except Exception as e:
                print(f"Migration warning for {table}: {e}")

        # Fix system_settings: remove UNIQUE constraint on 'key' by recreating the table
        # This allows per-user settings (same key, different user_id)
        try:
            indexes = list(conn.execute(text("PRAGMA index_list(system_settings)")))
            has_unique_key = any(
                row[1].lower().startswith("ix_") or "key" in row[1].lower()
                for row in indexes
                if row[2] == 1  # unique=1
            )
            # Check via table creation SQL
            create_sql_row = conn.execute(text(
                "SELECT sql FROM sqlite_master WHERE type='table' AND name='system_settings'"
            )).fetchone()
            if create_sql_row and "UNIQUE" in (create_sql_row[0] or "").upper():
                # Recreate without UNIQUE on key
                conn.execute(text("ALTER TABLE system_settings RENAME TO system_settings_old"))
                conn.execute(text("""
                    CREATE TABLE system_settings (
                        id INTEGER PRIMARY KEY,
                        key VARCHAR(100) NOT NULL,
                        value JSON,
                        updated_at DATETIME,
                        user_id INTEGER REFERENCES users(id)
                    )
                """))
                conn.execute(text("INSERT INTO system_settings SELECT id, key, value, updated_at, user_id FROM system_settings_old"))
                conn.execute(text("DROP TABLE system_settings_old"))
                conn.commit()
                print("Migration: system_settings UNIQUE constraint on key removed.")
        except Exception as e:
            print(f"Migration warning for system_settings UNIQUE fix: {e}")