from __future__ import annotations

import sys
from datetime import date, datetime, timedelta

import polars as pl
import yaml

from log import log

from clickhouse_task.create_table import create_clickhouse_table
from clickhouse_task.delete_task import delete_existing_data , truncate_table
from clickhouse_task.load_table import load_to_clickhouse

from db_con.connection import (
    build_sql_server_engine,
    build_clickhouse_engine,
    get_clickhouse_client,
)

from mids import MID_TABLE_COV, MID_TABLE_COV1

from masters.dimensions import *
from masters.bridge import *
from kpi.facts import *


# ============================================================
# Helpers
# ============================================================

def get_dataframe(
    fn_name: str,
    fetch_by: str,
    sql_engine,
    mids,
    run_date,
) -> pl.DataFrame:

    fn = globals()[fn_name]

    if fetch_by == "mids":
        return fn(sql_engine, mids)

    if fetch_by == "run_date":
        return fn(sql_engine, run_date)

    return fn(sql_engine)


def ensure_table_exists(
    client,
    clickhouse_engine,
    table_name: str,
    df: pl.DataFrame,
) -> bool:

    exists = client.command(
        f"EXISTS TABLE {table_name}"
    )

    if not exists:
        log.info(
            "Creating ClickHouse table: %s",
            table_name,
        )

        create_clickhouse_table(
            df=df,
            table_name=table_name,
            clickhouse_engine=clickhouse_engine,
        )

    return bool(exists)


# ============================================================
# Main
# ============================================================

def main():

    log.info("=" * 80)
    log.info("Hello from data-move Python data pipeline !")

    # --------------------------------------------------------
    # Run Date
    # --------------------------------------------------------

    if len(sys.argv) > 1:
        run_date = datetime.strptime(
            sys.argv[1],
            "%Y-%m-%d",
        ).date()
    else:
        run_date = date.today() - timedelta(days=1)

    log.info(
        "Pipeline Run Date : %s",
        run_date,
    )

    # --------------------------------------------------------
    # Connections
    # --------------------------------------------------------

    log.info(
        "Connecting to SQL Server and ClickHouse"
    )

    sql_engine = build_sql_server_engine()

    clickhouse_engine = (
        build_clickhouse_engine()
    )

    client = get_clickhouse_client()

    log.info(
        "Database connections established"
    )

    # --------------------------------------------------------
    # Collect Delete Keys
    # --------------------------------------------------------

    mids = MID_TABLE_COV(
        sql_engine,
        run_date,
    )

    emp_visit_df = MID_TABLE_COV1(
        sql_engine,
        run_date,
    )

    # --------------------------------------------------------
    # Delete Existing Data
    # --------------------------------------------------------

    delete_existing_data(
        client=client,
        run_date=run_date,
        mids=mids,
        emp_visit_df=emp_visit_df,
    )

    # --------------------------------------------------------
    # Load Config
    # --------------------------------------------------------

    with open(
        "tables.yml",
        "r",
    ) as file:

        config = yaml.safe_load(file)

    # --------------------------------------------------------
    # Process Tables
    # --------------------------------------------------------

    for table in config["tables"]:

        table_name = table["name"]
        table_type = table["type"]
        operation = table["operation"]
        fetch_by = table["fetch_by"]

        log.info("=" * 80)

        log.info(
            "TABLE=%s | TYPE=%s | OPERATION=%s",
            table_name,
            table_type,
            operation,
        )

        try:

            # --------------------------------------------
            # Fetch
            # --------------------------------------------

            fn_name = f"fetch_{table_name}"

            df = get_dataframe(
                fn_name=fn_name,
                fetch_by=fetch_by,
                sql_engine=sql_engine,
                mids=mids,
                run_date=run_date,
            )

            if df.is_empty():

                log.warning(
                    "%s returned no rows",
                    table_name,
                )

                continue

            log.info(
                "Fetched %s rows",
                len(df),
            )

            # --------------------------------------------
            # Create Table if Missing
            # --------------------------------------------

            exists = ensure_table_exists(
                client=client,
                clickhouse_engine=clickhouse_engine,
                table_name=table_name,
                df=df,
            )

            # --------------------------------------------
            # Full Refresh Tables
            # --------------------------------------------

            if exists and operation == "DELETE+INSERT":

                truncate_table(
                    client,
                    table_name,
                )

                log.info(
                    "Truncated %s",
                    table_name,
                )

            # --------------------------------------------
            # Load
            # --------------------------------------------

            load_to_clickhouse(
                client=client,
                table_name=table_name,
                df=df,
            )

            log.info(
                "%s loaded successfully (%s rows)",
                table_name,
                len(df),
            )

        except Exception as e:

            log.exception(
                "Failed processing table %s",
                table_name,
            )

            raise

    log.info("=" * 80)
    log.info("Pipeline Completed Successfully")
    log.info("=" * 80)


if __name__ == "__main__":
    main()