"""
One-time migration: backfill amount_usd on purchase credit_transactions.

Matches pack by:
  1. pack_id extracted from description "Purchased <pack_id> pack (...)"
  2. Fallback: closest credits count match from app_settings packs
  3. Fallback: test pack = $1.00
"""
import asyncio
import re
import sys
import os

sys.path.insert(0, os.path.dirname(os.path.dirname(__file__)))

PACK_PRICES = {
    "starter": 49.0,
    "pro":     199.0,
    "scale":   499.0,
    "test":    1.0,
}

CREDITS_TO_PACK = {
    50:  ("starter", 49.0),
    220: ("pro",     199.0),
    600: ("scale",   499.0),
}


def _resolve_price(description: str, credits: int) -> float | None:
    """Return USD price for a transaction, or None if can't determine."""
    # Try to extract pack_id from description
    m = re.match(r"Purchased\s+(\S+)\s+pack", description or "", re.IGNORECASE)
    if m:
        pack_id = m.group(1).lower()
        if pack_id in PACK_PRICES:
            return PACK_PRICES[pack_id]

    # Fallback: exact credits match
    if credits in CREDITS_TO_PACK:
        return CREDITS_TO_PACK[credits][1]

    # Fallback: closest credits match within 10%
    for c, (_, price) in CREDITS_TO_PACK.items():
        if abs(c - credits) / max(c, 1) < 0.1:
            return price

    return None


async def main():
    from motor.motor_asyncio import AsyncIOMotorClient
    from app.config import Config

    mongo_uri = os.environ.get("MONGO_URI", Config.MONGO_URI)
    db_name = mongo_uri.rstrip("/").split("/")[-1].split("?")[0] or "cohorta_db"
    client = AsyncIOMotorClient(mongo_uri)
    db = client[db_name]

    cursor = db.credit_transactions.find({
        "type": "purchase",
        "amount_usd": {"$exists": False},
    })

    updated = 0
    skipped = 0

    async for tx in cursor:
        description = tx.get("description", "")
        credits = tx.get("amount", 0)
        price = _resolve_price(description, credits)

        if price is None:
            print(f"  SKIP  id={tx['_id']}  desc='{description}'  credits={credits}  — cannot determine price")
            skipped += 1
            continue

        await db.credit_transactions.update_one(
            {"_id": tx["_id"]},
            {"$set": {"amount_usd": price}},
        )
        print(f"  SET   id={tx['_id']}  desc='{description}'  credits={credits}  → ${price}")
        updated += 1

    print(f"\nDone: {updated} updated, {skipped} skipped.")
    client.close()


if __name__ == "__main__":
    asyncio.run(main())