import pyodbc
import pandas as pd
import clickhouse_connect
from datetime import datetime
import warnings

# ---------------------------------------------------
# Suppress Pandas Warning
# ---------------------------------------------------
warnings.filterwarnings(
    'ignore',
    'pandas only supports SQLAlchemy connectable'
)

print("SCHEMA Migration Started :", datetime.now())

# ---------------------------------------------------
# SQL Server Connection
# ---------------------------------------------------
SQL_CONN_STR = (
    'DRIVER={ODBC Driver 17 for SQL Server};'
    'SERVER=10.200.25.65;'
    'DATABASE=CPMIndiaBusinessInsight;'
    'UID=bsgteam_test;'
    'PWD=B$gt3@m#00512;'
    'TrustServerCertificate=yes;'
)

# ---------------------------------------------------
# ClickHouse Connection
# ---------------------------------------------------
CH_CONFIG = {
    'host': '172.188.12.194',
    'port': 8123,
    'username': 'default',
    'password': 'dipanshu_k',
    'database': 'DaburIndia_BI'
}

# ---------------------------------------------------
# SQL Server → ClickHouse Datatype Mapping
# ---------------------------------------------------
DATATYPE_MAPPING = {

    'bigint': 'Int64',
    'int': 'Int32',
    'smallint': 'Int16',
    'tinyint': 'Int8',
    'bit': 'UInt8',

    'float': 'Float64',
    'real': 'Float32',
    'decimal': 'Float64',
    'numeric': 'Float64',
    'money': 'Float64',

    'varchar': 'String',
    'nvarchar': 'String',
    'char': 'String',
    'nchar': 'String',
    'text': 'String',
    'ntext': 'String',
    'xml': 'String',

    'date': 'Date32',
    'datetime': 'DateTime64',
    'datetime2': 'DateTime64',
    'smalldatetime': 'DateTime64',

    'time': 'String',

    'uniqueidentifier': 'String',

    'binary': 'String',
    'varbinary': 'String'
}

try:

    # ---------------------------------------------------
    # Connect SQL Server
    # ---------------------------------------------------
    sql_conn = pyodbc.connect(SQL_CONN_STR)

    print("Connected to SQL Server")

    # ---------------------------------------------------
    # Connect ClickHouse
    # ---------------------------------------------------
    ch_client = clickhouse_connect.get_client(**CH_CONFIG)

    print("Connected to ClickHouse")

    # ---------------------------------------------------
    # Create Database if Not Exists
    # ---------------------------------------------------
    create_database_query = f"""
    CREATE DATABASE IF NOT EXISTS `{CH_CONFIG['database']}`
    """

    ch_client.command(create_database_query)

    print(f"Database Verified : {CH_CONFIG['database']}")

    # ---------------------------------------------------
    # Get All SQL Server Tables
    # ---------------------------------------------------
    table_query = """
    SELECT TABLE_NAME
    FROM INFORMATION_SCHEMA.TABLES
    WHERE TABLE_TYPE = 'BASE TABLE'
    AND TABLE_SCHEMA = 'dbo'
    ORDER BY TABLE_NAME
    """

    tables_df = pd.read_sql(table_query, sql_conn)

    tables = tables_df['TABLE_NAME'].tolist()

    print(f"Total Tables Found : {len(tables)}")

    # ---------------------------------------------------
    # Process Each Table
    # ---------------------------------------------------
    for table_name in tables:

        try:

            print("\n===================================")
            print(f"Creating Table : {table_name}")
            print("===================================")

            # ---------------------------------------------------
            # Safe Table Name
            # ---------------------------------------------------
            safe_table_name = (
                table_name
                .replace('`', '')
                .replace('[', '')
                .replace(']', '')
            )

            # ---------------------------------------------------
            # Get Table Schema
            # ---------------------------------------------------
            schema_query = """
            SELECT
                COLUMN_NAME,
                DATA_TYPE,
                IS_NULLABLE
            FROM INFORMATION_SCHEMA.COLUMNS
            WHERE TABLE_NAME = ?
            ORDER BY ORDINAL_POSITION
            """

            schema_df = pd.read_sql(
                schema_query,
                sql_conn,
                params=[safe_table_name]
            )

            # ---------------------------------------------------
            # Skip Empty Schema
            # ---------------------------------------------------
            if schema_df.empty:

                print(f"No Columns Found : {safe_table_name}")
                continue

            # ---------------------------------------------------
            # Build ClickHouse Columns
            # ---------------------------------------------------
            columns = []

            for _, row in schema_df.iterrows():

                col_name = str(row['COLUMN_NAME']).replace('`', '')

                sql_type = str(row['DATA_TYPE']).lower()

                nullable = str(row['IS_NULLABLE'])

                # ---------------------------------------------------
                # Get ClickHouse Datatype
                # ---------------------------------------------------
                ch_type = DATATYPE_MAPPING.get(
                    sql_type,
                    'String'
                )

                # ---------------------------------------------------
                # Nullable Handling
                # ---------------------------------------------------
                if nullable == 'YES':
                    ch_type = f'Nullable({ch_type})'

                columns.append(
                    f"`{col_name}` {ch_type}"
                )

            # ---------------------------------------------------
            # Generate CREATE TABLE Query
            # ---------------------------------------------------
            create_table_query = f"""
            CREATE TABLE IF NOT EXISTS `{CH_CONFIG['database']}`.`{safe_table_name}`
            (
                {', '.join(columns)}
            )
            ENGINE = MergeTree()
            ORDER BY tuple()
            """

            # ---------------------------------------------------
            # Print SQL
            # ---------------------------------------------------
            print("\nGenerated CREATE TABLE SQL:\n")
            print(create_table_query)

            # ---------------------------------------------------
            # Save SQL Log
            # ---------------------------------------------------
            with open(
                "clickhouse_schema_debug.log",
                "a",
                encoding="utf-8"
            ) as log_file:

                log_file.write("\n\n=====================================\n")
                log_file.write(f"TABLE : {safe_table_name}\n")
                log_file.write(create_table_query)
                log_file.write("\n=====================================\n")

            # ---------------------------------------------------
            # Execute CREATE TABLE
            # ---------------------------------------------------
            ch_client.command(create_table_query)

            print(f"Table Created Successfully : {safe_table_name}")

        except Exception as table_error:

            print("\n===================================")
            print(f"FAILED TABLE : {table_name}")
            print("ERROR :", str(table_error))
            print("===================================")

            # ---------------------------------------------------
            # Error Logging
            # ---------------------------------------------------
            with open(
                "clickhouse_schema_error.log",
                "a",
                encoding="utf-8"
            ) as error_log:

                error_log.write("\n\n=====================================\n")
                error_log.write(f"TABLE : {table_name}\n")
                error_log.write(f"ERROR : {str(table_error)}\n")
                error_log.write("=====================================\n")

            continue

    print("\n===================================")
    print("ALL TABLE STRUCTURES CREATED")
    print("===================================")

except Exception as e:

    print("\n===================================")
    print("MAIN ERROR :", str(e))
    print("===================================")

finally:

    # ---------------------------------------------------
    # Close Connections
    # ---------------------------------------------------
    try:
        sql_conn.close()
        print("SQL Server Connection Closed")
    except:
        pass

    try:
        ch_client.close()
        print("ClickHouse Connection Closed")
    except:
        pass

print("Finished :", datetime.now())