from __future__ import annotations

import argparse
from pathlib import Path
from typing import Optional

from .db import DEFAULT_DB_PATH, connect, init_db, load_sample_data
from .indicators import compute_area_scores
from .reporting import format_scores_table, write_monthly_report


def build_parser() -> argparse.ArgumentParser:
    parser = argparse.ArgumentParser(
        prog="shanghai_housing",
        description="Shanghai housing market research toolkit.",
    )
    parser.add_argument(
        "--db",
        type=Path,
        default=DEFAULT_DB_PATH,
        help=f"SQLite database path. Default: {DEFAULT_DB_PATH}",
    )

    subparsers = parser.add_subparsers(dest="command", required=True)
    subparsers.add_parser("init-db", help="Create or update the SQLite schema.")
    subparsers.add_parser("load-sample", help="Load demonstration sample data.")

    score_parser = subparsers.add_parser("score", help="Print area scores for a month.")
    score_parser.add_argument("--month", required=True, help="Month in YYYY-MM format.")

    report_parser = subparsers.add_parser("report", help="Generate a monthly Markdown report.")
    report_parser.add_argument("--month", required=True, help="Month in YYYY-MM format.")
    report_parser.add_argument(
        "--output",
        type=Path,
        help="Output Markdown path. Default: reports/monthly-YYYY-MM.md",
    )

    return parser


def main(argv: Optional[list[str]] = None) -> int:
    parser = build_parser()
    args = parser.parse_args(argv)

    if args.command == "init-db":
        path = init_db(args.db)
        print(f"Initialized database: {path}")
        return 0

    if args.command == "load-sample":
        load_sample_data(args.db)
        print(f"Loaded sample data into: {args.db}")
        return 0

    if args.command == "score":
        with connect(args.db) as conn:
            scores = compute_area_scores(conn, args.month)
        print(format_scores_table(scores))
        return 0

    if args.command == "report":
        output = args.output or Path("reports") / f"monthly-{args.month}.md"
        with connect(args.db) as conn:
            path = write_monthly_report(conn, args.month, output)
        print(f"Generated report: {path}")
        return 0

    parser.error(f"Unknown command: {args.command}")
    return 2