# =============================================================================
# Projet : AIR — Accounting Intermediate Representation
# Auteur : Simon-Pierre Boucher
# Contact : contact@spboucher.ai
# Fichier : mapper.py
# Description : Lower a CompiledJournal to QuickBooks Online JournalEntry payloads (pure, offline).
# =============================================================================
"""CompiledJournal -> QBO JournalEntry payloads.

Pure lowering, no network: this module runs identically with or without a
QuickBooks account, so the whole backend is testable offline.

Shape per docs/research/erp-apis.md (QBO API, minorversion=75 baseline):
- Line[] with unsigned Amount + PostingType ("Debit"/"Credit") + AccountRef
- DocNumber max 21 chars (longer ids are truncated with a stable hash suffix)
- amounts stay Decimal end-to-end here; serialization to exact JSON numbers
  is the transport's job (never through float).
"""
from __future__ import annotations

import hashlib
from typing import Any

from core.journal import CompiledJournal, JournalEntry, Side

DOCNUMBER_MAX = 21


class AccountMappingError(KeyError):
    """An account code has no QuickBooks AccountRef mapping."""


def doc_number(entry_id: str) -> str:
    """QBO DocNumber (<= 21 chars), stable for a given entry id."""
    if len(entry_id) <= DOCNUMBER_MAX:
        return entry_id
    digest = hashlib.sha256(entry_id.encode("utf-8")).hexdigest()[:6]
    return f"{entry_id[:DOCNUMBER_MAX - 7]}-{digest}"


def map_entry(
    entry: JournalEntry,
    account_map: dict[str, dict[str, str]] | None = None,
) -> dict[str, Any]:
    """One JournalEntry -> one QBO JournalEntry create body.

    account_map: our account code -> {"value": <qbo account id>, "name": ...}.
    When None, the code itself is used as the AccountRef value (fine for the
    mock transport and for offline export; a real realm needs the map).
    """
    lines: list[dict[str, Any]] = []
    for line in entry.lines:
        if account_map is not None:
            try:
                ref = account_map[line.account.code]
            except KeyError:
                raise AccountMappingError(
                    f"account '{line.account.code} {line.account.name}' has no "
                    "QuickBooks AccountRef in the account map; add it or post "
                    "to the native backend instead"
                ) from None
        else:
            ref = {"value": line.account.code, "name": line.account.name}
        lines.append({
            "Description": line.memo,
            "Amount": line.amount.amount,          # Decimal, exact
            "DetailType": "JournalEntryLineDetail",
            "JournalEntryLineDetail": {
                "PostingType": "Debit" if line.side is Side.DEBIT else "Credit",
                "AccountRef": dict(ref),
            },
        })
    return {
        "DocNumber": doc_number(entry.id),
        "TxnDate": entry.date.isoformat(),
        "PrivateNote": (
            f"{entry.description} | AIR event {entry.source_event_id} | "
            f"policies {entry.policy_set}@{entry.policy_version}"
        ),
        "Line": lines,
        "CurrencyRef": {"value": entry.lines[0].amount.currency},
    }


def map_journal(
    journal: CompiledJournal,
    account_map: dict[str, dict[str, str]] | None = None,
) -> list[dict[str, Any]]:
    return [map_entry(entry, account_map) for entry in journal.entries]


def contra_body(body: dict[str, Any]) -> dict[str, Any]:
    """Reversal payload: QBO has no native journal-entry reversal, so we
    synthesize an exact contra entry (sides swapped, amounts identical)."""
    contra = {
        "DocNumber": doc_number("R" + body["DocNumber"]),
        "TxnDate": body["TxnDate"],
        "PrivateNote": "REVERSAL of " + body["DocNumber"] + " | " + body["PrivateNote"],
        "Line": [],
        "CurrencyRef": dict(body["CurrencyRef"]),
    }
    for line in body["Line"]:
        detail = line["JournalEntryLineDetail"]
        contra["Line"].append({
            "Description": "reversal: " + line["Description"],
            "Amount": line["Amount"],
            "DetailType": "JournalEntryLineDetail",
            "JournalEntryLineDetail": {
                "PostingType": ("Credit" if detail["PostingType"] == "Debit"
                                else "Debit"),
                "AccountRef": dict(detail["AccountRef"]),
            },
        })
    return contra