#!/usr/bin/env python3

import csv
from decimal import Decimal, InvalidOperation
import sys
from pathlib import Path
import hashlib
from collections import defaultdict


def transaction_hash(date, payee, desc, amount):
    """Generate a stable hash for each transaction."""
    base = f"{date}|{payee}|{desc}|{amount}"
    return hashlib.md5(base.encode("utf-8")).hexdigest()[:10]  # short ID


def convert(in_path, out_path):
    with open(in_path, newline="", encoding="utf-8-sig") as f_in, \
         open(out_path, "w", newline="", encoding="utf-8") as f_out:

        reader = csv.DictReader(f_in)

        # Add UniqueID field to prevent Actual from treating repeated merchants as duplicates
        fieldnames = ["Date", "Payee", "Description", "Amount", "UniqueID"]
        writer = csv.DictWriter(f_out, fieldnames=fieldnames)
        writer.writeheader()

        seen_hashes = defaultdict(int)
        skipped = 0

        for row in reader:
            if not row:
                continue

            date = (row.get("Transaction Date") or "").strip()
            if not date:
                continue

            desc = (row.get("Transaction Description") or "").strip()
            payee = desc or (row.get("Transaction Type") or "").strip()

            debit_str = (row.get("Debit Amount") or "").replace(",", "").strip()
            credit_str = (row.get("Credit Amount") or "").replace(",", "").strip()
            amount = None

            if debit_str:
                try:
                    amount = -Decimal(debit_str)
                except InvalidOperation:
                    continue
            elif credit_str:
                try:
                    amount = Decimal(credit_str)
                except InvalidOperation:
                    continue
            else:
                continue

            # Generate transaction fingerprint
            unique_id = transaction_hash(date, payee, desc, amount)

            # Check if we've seen this transaction hash already
            seen_hashes[unique_id] += 1
            if seen_hashes[unique_id] > 1:
                # Optional: skip true duplicates or just warn
                print(f"⚠️ Duplicate detected: {date} | {payee} | {amount}")
                skipped += 1
                continue

            writer.writerow({
                "Date": date,
                "Payee": payee,
                "Description": desc,
                "Amount": f"{amount:.2f}",
                "UniqueID": unique_id,
            })

    print(f"\n✅ Written cleaned file to {out_path}")
    if skipped:
        print(f"⚠️ Skipped {skipped} duplicate entries based on content hash.")


def main():
    if len(sys.argv) < 2:
        print("Usage: python clean_halifax_actual.py input.csv [output.csv]")
        sys.exit(1)

    in_path = Path(sys.argv[1])

    if len(sys.argv) >= 3:
        out_path = Path(sys.argv[2])
    else:
        out_path = in_path.with_name(in_path.stem + "_actual.csv")

    convert(in_path, out_path)


if __name__ == "__main__":
    main()