from __future__ import annotations

import hashlib
import json
import re
from datetime import date, datetime
from decimal import Decimal
from typing import Any


def _stable_default(value: Any) -> str:
    if isinstance(value, datetime | date):
        return value.isoformat()
    if isinstance(value, Decimal):
        return str(value)
    return str(value)


def _stable_json(value: Any) -> str:
    return json.dumps(
        value, default=_stable_default, ensure_ascii=False, sort_keys=True, separators=(",", ":")
    )


def compute_raw_observation_hash(
    *,
    source_type: str,
    source_reference: str | None = None,
    raw_text: str | None = None,
    raw_payload: dict[str, Any] | None = None,
) -> str:
    payload = {
        "source_reference": source_reference,
        "source_type": source_type,
        "raw_payload": raw_payload or {},
        "raw_text": raw_text or "",
    }
    return hashlib.sha256(_stable_json(payload).encode("utf-8")).hexdigest()


def normalize_counterparty(value: str | None) -> str:
    if not value:
        return ""
    compact = re.sub(r"[^a-z0-9]+", " ", value.lower())
    return re.sub(r"\s+", " ", compact).strip()


def compute_normalized_transaction_fingerprint(
    *,
    amount: Decimal | str | int | float,
    currency: str,
    event_date: date | str,
    merchant: str | None = None,
    counterparty: str | None = None,
    external_id: str | None = None,
) -> str:
    normalized = {
        "amount": str(Decimal(str(amount)).quantize(Decimal("0.01"))),
        "currency": currency.upper(),
        "event_date": event_date.isoformat() if isinstance(event_date, date) else event_date,
        "party": normalize_counterparty(merchant or counterparty),
        "external_id": external_id or "",
    }
    return hashlib.sha256(_stable_json(normalized).encode("utf-8")).hexdigest()