"""Seed seasons into a local MongoDB instance with unique ``season``.

Rules:
- initial_year starts from 2016.
- Determine current_year by today's date:
  - If today > July 1 (strict), current_year = this_year + 1
  - Else, current_year = this_year
- Generate seasons from initial_year up to (but excluding) current_year, as strings
  like "YYYY-YYYY+1". Stop when initial_year == current_year.
- Ensure unique index on ``season`` and upsert each document.

Environment variables (with defaults):
- DATABANK_DB_URI (default: mongodb://localhost:27017)
- DATABANK_DB_NAME (default: databank)

Usage (PowerShell):
  python -m pip install "pymongo>=4.7"
  $env:DATABANK_DB_URI = "mongodb://localhost:27017"
  $env:DATABANK_DB_NAME = "databank"
  python scripts/seed_seasons_mongo.py
"""

from __future__ import annotations

import os
from datetime import date
from typing import Any, Dict, Iterable, List, Tuple

from pymongo import MongoClient


def get_connection() -> Tuple[MongoClient, str]:
    """Create a MongoDB client and return ``(client, db_name)``."""
    uri = os.getenv("DATABANK_DB_URI", "mongodb://localhost:27017")
    name = os.getenv("DATABANK_DB_NAME", "databank")
    client = MongoClient(uri)
    return client, name


def calc_current_year(today: date | None = None) -> int:
    """Calculate current_year per rule (> July 1 => year+1 else year)."""
    today = today or date.today()
    threshold = date(today.year, 7, 1)
    return today.year + 1 if today > threshold else today.year


def generate_seasons(initial_year: int, current_year: int) -> List[Dict[str, Any]]:
    """Generate season documents from initial_year to current_year (exclusive)."""
    seasons: List[Dict[str, Any]] = []
    for start in range(initial_year, current_year):
        end = start + 1
        seasons.append(
            {
                "season": f"{start}-{end}",
                "start_year": start,
                "end_year": end,
            }
        )
    return seasons


def ensure_unique_index_seasons(db) -> None:
    """Ensure a unique index on seasons.season."""
    seasons = db["seasons"]
    seasons.create_index("season", unique=True)


def upsert_seasons(db, docs: Iterable[Dict[str, Any]]) -> Dict[str, int]:
    """Upsert provided season docs by ``season``; return counters."""
    seasons = db["seasons"]
    inserted = 0
    updated = 0
    for doc in docs:
        key = {"season": doc["season"]}
        result = seasons.replace_one(key, doc, upsert=True)
        if result.matched_count:
            updated += int(result.modified_count == 1)
        else:
            inserted += 1
    return {"inserted": inserted, "updated": updated}


def main() -> None:
    """Entry point to seed season documents into MongoDB with unique ``season``."""
    client, db_name = get_connection()
    try:
        db = client[db_name]
        ensure_unique_index_seasons(db)

        initial_year = 2016
        current = calc_current_year()
        docs = generate_seasons(initial_year, current)

        stats = upsert_seasons(db, docs)
        print(
            f"Seasons seed done: range=[{initial_year}, {current}) "
            f"inserted={stats['inserted']}, updated={stats['updated']}"
        )
    finally:
        client.close()


if __name__ == "__main__":
    main()