from typing import List
import aiomysql

from app.models.instance import Instance
from app.services.db_connector import DBConnector


class InstanceService:

    @staticmethod
    async def test_connection(instance: Instance) -> dict:
        """Test database connection using DBConnector."""
        result = await DBConnector.test_connection(instance)

        # Update instance status based on result
        if result.success:
            instance.status = "connected"
            instance.version = result.version
        else:
            instance.status = "error"

        return result.to_dict()

    @staticmethod
    async def list_databases(instance: Instance) -> List[str]:
        """List databases for the given instance type."""
        if instance.db_type == "mysql":
            conn = await aiomysql.connect(
                host=instance.host, port=instance.port,
                user=instance.username, password=instance.password,
            )
            try:
                async with conn.cursor() as cur:
                    await cur.execute("SHOW DATABASES")
                    rows = await cur.fetchall()
                return [row[0] for row in rows if row[0] not in ("information_schema", "mysql", "performance_schema", "sys")]
            finally:
                conn.close()
        elif instance.db_type in ("postgres", "postgresql"):
            import asyncpg
            dsn = f"postgresql://{instance.username}:{instance.password}@{instance.host}:{instance.port}/postgres"
            conn = await asyncpg.connect(dsn)
            try:
                rows = await conn.fetch("SELECT datname FROM pg_database WHERE datistemplate = false")
                return [r["datname"] for r in rows]
            finally:
                await conn.close()
        elif instance.db_type == "redis":
            from app.services.redis_connector import RedisConnector
            conn = await RedisConnector.get_connection(instance)
            try:
                db_count = await conn.config_get("databases")
                num = int(db_count.get("databases", 16))
                return [f"db{i}" for i in range(num)]
            finally:
                await conn.close()
        elif instance.db_type == "mongo":
            from pymongo import MongoClient
            pwd = instance.password
            if pwd and not pwd.startswith("$"):
                from app.core.crypto import decrypt_password
                try:
                    pwd = decrypt_password(pwd)
                except Exception:
                    pass
            uri = f"mongodb://{instance.username}:{pwd}@{instance.host}:{instance.port}/admin"
            client = MongoClient(uri, serverSelectionTimeoutMS=5000)
            try:
                dbs = client.list_database_names()
                return [d for d in dbs if d not in ("admin", "config", "local")]
            finally:
                client.close()
        elif instance.db_type == "sqlite":
            return [instance.database or "main"]
        else:
            return []

    @staticmethod
    async def list_tables(instance: Instance, database: str) -> List[dict]:
        """List tables in a database."""
        if instance.db_type == "mysql":
            conn = await aiomysql.connect(
                host=instance.host, port=instance.port,
                user=instance.username, password=instance.password,
                db=database,
            )
            try:
                async with conn.cursor(aiomysql.DictCursor) as cur:
                    await cur.execute(
                        "SELECT TABLE_NAME as name, TABLE_ROWS as rows, TABLE_TYPE as type "
                        "FROM information_schema.TABLES WHERE TABLE_SCHEMA = %s",
                        (database,)
                    )
                    return await cur.fetchall()
            finally:
                conn.close()
        elif instance.db_type in ("postgres", "postgresql"):
            import asyncpg
            dsn = f"postgresql://{instance.username}:{instance.password}@{instance.host}:{instance.port}/{database}"
            conn = await asyncpg.connect(dsn)
            try:
                rows = await conn.fetch(
                    "SELECT tablename as name FROM pg_tables WHERE schemaname = 'public'"
                )
                return [dict(r) for r in rows]
            finally:
                await conn.close()
        elif instance.db_type == "mongo":
            from pymongo import MongoClient
            pwd = instance.password
            if pwd and not pwd.startswith("$"):
                from app.core.crypto import decrypt_password
                try:
                    pwd = decrypt_password(pwd)
                except Exception:
                    pass
            uri = f"mongodb://{instance.username}:{pwd}@{instance.host}:{instance.port}/{database}"
            client = MongoClient(uri, serverSelectionTimeoutMS=5000)
            try:
                db_obj = client[database]
                colls = db_obj.list_collection_names()
                return [{"name": c} for c in colls]
            finally:
                client.close()
        elif instance.db_type == "sqlite":
            import sqlite3
            db_path = instance.host
            conn = sqlite3.connect(db_path)
            cur = conn.execute("SELECT name FROM sqlite_master WHERE type='table'")
            tables = [{"name": row[0]} for row in cur.fetchall()]
            conn.close()
            return tables
        else:
            return []