from __future__ import annotations
import logging
import sys
from pathlib import Path

import click

from .config import ImportConfig, SheetConfig
from .importer import Importer
from .reader import ExcelReader


def _setup_logging(verbose: bool):
    level = logging.DEBUG if verbose else logging.INFO
    logging.basicConfig(format="%(levelname)s  %(message)s", level=level)


@click.group()
def main():
    """Generic Excel-to-database import tool (Oracle & PostgreSQL)."""


@main.command()
@click.argument("excel_file", type=click.Path(exists=True))
@click.argument("config_file", type=click.Path(exists=True))
@click.option("-v", "--verbose", is_flag=True)
def run(excel_file: str, config_file: str, verbose: bool):
    """Import EXCEL_FILE using CONFIG_FILE (YAML)."""
    _setup_logging(verbose)
    cfg = ImportConfig.from_yaml(config_file)
    importer = Importer(cfg)
    try:
        results = importer.run(excel_file)
    except Exception as exc:
        click.echo(f"ERROR: {exc}", err=True)
        sys.exit(1)

    for table, rows in results.items():
        click.echo(f"  {table}: {rows} rows imported")


@main.command()
@click.argument("excel_file", type=click.Path(exists=True))
def inspect(excel_file: str):
    """Show sheet names and column preview of EXCEL_FILE."""
    reader = ExcelReader(excel_file)
    names = reader.sheet_names()
    click.echo(f"Sheets in {Path(excel_file).name}:")
    for i, name in enumerate(names):
        click.echo(f"  [{i}] {name}")
        # read first few rows for preview
        from .config import SheetConfig as SC
        df = reader.read(SC(sheet=i))
        click.echo(f"      Columns ({len(df.columns)}): {', '.join(str(c) for c in df.columns[:8])}")
        if len(df.columns) > 8:
            click.echo(f"      ... and {len(df.columns) - 8} more")
        click.echo(f"      Rows: {len(df)}")


@main.command("generate-config")
@click.argument("excel_file", type=click.Path(exists=True))
@click.option("--dsn", default="postgresql+psycopg2://user:pass@localhost/dbname", show_default=True)
@click.option("--output", "-o", default="import_config.yaml", show_default=True)
def generate_config(excel_file: str, dsn: str, output: str):
    """Generate a starter YAML config from EXCEL_FILE's structure."""
    import yaml
    reader = ExcelReader(excel_file)
    names = reader.sheet_names()

    sheets = []
    for i, name in enumerate(names):
        from .config import SheetConfig as SC
        df = reader.read(SC(sheet=i))
        table_name = name.lower().replace(" ", "_")
        columns = [{"source": str(c), "target": str(c).lower().replace(" ", "_")} for c in df.columns]
        sheets.append({
            "sheet": name,
            "header_row": 0,
            "target_table": table_name,
            "mode": "append",
            "columns": columns,
        })

    config = {"dsn": dsn, "sheets": sheets}
    with open(output, "w") as f:
        yaml.dump(config, f, allow_unicode=True, sort_keys=False)
    click.echo(f"Config written to {output}")