from django.db import transaction
from django.utils import timezone

from commerce.integrations.moysklad import MoySkladError
from commerce.models import ExternalProject, ProjectPayment, Sale, SourceRecord
from commerce.services.ingestion import ingest_source_record
from commerce.services.moysklad_sync import (
    _document_currency,
    _external_id,
    _money,
    _reference_external_id,
    _source_updated_at,
)


def project_reference(source, row):
    if not isinstance(row, dict):
        return None
    external_id = _reference_external_id(row)
    if not external_id:
        return None
    project, _ = ExternalProject.objects.get_or_create(
        source=source,
        external_id=external_id,
        defaults={"name": str(row.get("name") or external_id)[:255]},
    )
    # A reference must not erase information obtained from the full catalogue.
    if row.get("name") and project.name != row["name"]:
        project.name = str(row["name"])[:255]
        project.save(update_fields=["name"])
    return project


@transaction.atomic
def normalize_project(source, row):
    external_id = _external_id(row)
    if not external_id or not row.get("name"):
        raise MoySkladError("В проекте отсутствует ID или название.")
    ingest_source_record(
        source=source,
        entity_type="project",
        external_id=external_id,
        payload=row,
        source_updated_at=_source_updated_at(row),
    )
    project, _ = ExternalProject.objects.update_or_create(
        source=source,
        external_id=external_id,
        defaults={
            "name": str(row["name"])[:255],
            "code": str(row.get("code") or "")[:255],
            "description": str(row.get("description") or ""),
            "archived": bool(row.get("archived")),
            "synced_at": timezone.now(),
        },
    )
    return project


@transaction.atomic
def normalize_project_payment(source, row, document_type, seen_at):
    if document_type not in {"paymentout", "cashout"}:
        raise MoySkladError("Неподдерживаемый платёж проекта.")
    external_id = _external_id(row)
    occurred_at = _source_updated_at({"updated": row.get("moment")})
    if not external_id or not occurred_at or row.get("sum") is None:
        raise MoySkladError("В платеже отсутствует ID, дата или сумма.")
    amount = _money(row["sum"])
    if amount < 0:
        raise MoySkladError("Отрицательная сумма исходящего платежа.")
    record = ingest_source_record(
        source=source,
        entity_type=document_type,
        external_id=external_id,
        payload=row,
        source_updated_at=_source_updated_at(row),
    ).record
    payment, _ = ProjectPayment.objects.update_or_create(
        source=source,
        external_id=external_id,
        document_type=document_type,
        defaults={
            "source_record": record,
            "project": project_reference(source, row.get("project")),
            "number": str(row.get("name") or "")[:255],
            "description": str(
                row.get("paymentPurpose") or row.get("description") or ""
            ),
            "expense_category": str((row.get("expenseItem") or {}).get("name") or "")[
                :255
            ],
            "payee": str((row.get("agent") or {}).get("name") or "")[:255],
            "amount": amount,
            "currency": _document_currency(row),
            "occurred_at": occurred_at,
            "applicable": bool(row.get("applicable", False)) and not row.get("deleted"),
            "seen_at": seen_at,
            "missing_from_source": False,
        },
    )
    return payment


def restore_sale_projects(source):
    count = 0
    records = SourceRecord.objects.filter(
        source=source, entity_type__in=["demand", "salesreturn"]
    )
    for record in records.iterator(chunk_size=500):
        project = project_reference(source, record.payload.get("project"))
        if project:
            count += Sale.objects.filter(
                source_record=record, project__isnull=True
            ).update(project=project)
    return count


def sync_project_catalog(source, client):
    count = 0
    for archived in [False, True]:
        for row in client.iter_project_data("project", archived=archived):
            normalize_project(source, row)
            count += 1
    restore_sale_projects(source)
    return count


def sync_project_payments(source, client, progress=None):
    count = 0
    for document_type in ["paymentout", "cashout"]:
        seen_at = timezone.now()
        for row in client.iter_project_data(document_type):
            normalize_project_payment(source, row, document_type, seen_at)
            count += 1
            if progress and count % 25 == 0:
                progress(count)
        # Only a fully successful scan may retire missing documents. Keep history.
        ProjectPayment.objects.filter(
            source=source, document_type=document_type, seen_at__lt=seen_at
        ).update(missing_from_source=True)
    return count