from datetime import timedelta
from decimal import Decimal

import pytest
from django.utils import timezone

from commerce.models import (
    Cost,
    CostType,
    Product,
    ProductBinding,
    Sale,
    SaleEventType,
    SaleLine,
    SourceSystem,
    StockSnapshot,
)
from commerce.services import get_product_metrics, ingest_source_record, match_product

pytestmark = pytest.mark.django_db


def test_ingestion_is_idempotent_and_detects_payload_changes():
    source = SourceSystem.objects.create(code="moysklad", name="МойСклад")

    first = ingest_source_record(
        source=source,
        entity_type="product",
        external_id="product-1",
        payload={"name": "Фишка", "stock": 10},
    )
    repeated = ingest_source_record(
        source=source,
        entity_type="product",
        external_id="product-1",
        payload={"stock": 10, "name": "Фишка"},
    )
    changed = ingest_source_record(
        source=source,
        entity_type="product",
        external_id="product-1",
        payload={"name": "Фишка", "stock": 8},
    )

    assert first.created is True
    assert repeated.created is False
    assert repeated.changed is False
    assert changed.changed is True
    assert changed.record.pk == first.record.pk
    assert changed.record.payload["stock"] == 8


def test_product_matching_prefers_binding_and_rejects_ambiguous_sku():
    source = SourceSystem.objects.create(code="retailcrm", name="RetailCRM")
    first = Product.objects.create(sku="FISHKA-RED", name="Фишка красная")
    second = Product.objects.create(sku="FISHKA-BLUE", name="Фишка синяя")
    ProductBinding.objects.create(
        product=first,
        source=source,
        external_id="offer-1",
        external_sku="shared-sku",
    )
    ProductBinding.objects.create(
        product=second,
        source=source,
        external_id="offer-2",
        external_sku="shared-sku",
    )

    explicit = match_product(source=source, external_id="offer-1")
    ambiguous = match_product(source=source, external_sku="shared-sku")
    canonical = match_product(source=source, external_sku="fishka-blue")

    assert explicit.product == first
    assert explicit.method == "external_id"
    assert ambiguous.matched is False
    assert canonical.product == second
    assert canonical.method == "canonical_sku"


def test_product_metrics_include_returns_costs_and_latest_stock():
    now = timezone.now()
    source = SourceSystem.objects.create(code="moysklad", name="МойСклад")
    ads = SourceSystem.objects.create(code="ads", name="Реклама")
    product = Product.objects.create(sku="FISHKA", name="Фишка")

    sale = Sale.objects.create(
        source=source,
        external_id="sale-1",
        event_type=SaleEventType.SALE,
        channel="site",
        occurred_at=now - timedelta(days=2),
    )
    sale_line = SaleLine.objects.create(
        sale=sale,
        product=product,
        external_id="line-1",
        quantity=Decimal("2"),
        gross_amount=Decimal("1000"),
        discount_amount=Decimal("100"),
        cost_amount=Decimal("400"),
    )
    returned = Sale.objects.create(
        source=source,
        external_id="return-1",
        event_type=SaleEventType.RETURN,
        channel="site",
        occurred_at=now - timedelta(days=1),
    )
    SaleLine.objects.create(
        sale=returned,
        product=product,
        external_id="return-line-1",
        quantity=Decimal("1"),
        gross_amount=Decimal("200"),
        cost_amount=Decimal("80"),
    )
    Cost.objects.create(
        source=source,
        product=product,
        external_id="commission-1",
        cost_type=CostType.COMMISSION,
        amount=Decimal("50"),
        occurred_at=now,
    )
    Cost.objects.create(
        source=ads,
        sale_line=sale_line,
        external_id="ad-1",
        cost_type=CostType.ADVERTISING,
        amount=Decimal("20"),
        occurred_at=now,
    )

    StockSnapshot.objects.create(
        product=product,
        source=source,
        warehouse_external_id="main",
        quantity=Decimal("10"),
        reserved=Decimal("2"),
        captured_at=now - timedelta(hours=2),
    )
    StockSnapshot.objects.create(
        product=product,
        source=source,
        warehouse_external_id="main",
        quantity=Decimal("7"),
        reserved=Decimal("1"),
        captured_at=now,
    )
    StockSnapshot.objects.create(
        product=product,
        source=source,
        warehouse_external_id="reserve",
        quantity=Decimal("3"),
        captured_at=now,
    )

    result = get_product_metrics(product)
    rub = result["monetary"][0]

    assert rub["currency"] == "RUB"
    assert rub["quantity"] == Decimal("1")
    assert rub["gross_revenue"] == Decimal("800")
    assert rub["discounts"] == Decimal("100")
    assert rub["net_revenue"] == Decimal("700")
    assert rub["cost_of_goods"] == Decimal("320")
    assert rub["additional_costs"] == Decimal("70")
    assert rub["contribution_margin"] == Decimal("310")
    channels = {row["channel"]: row for row in result["by_channel"]}
    assert channels["site"]["net_revenue"] == Decimal("700")
    assert channels["site"]["additional_costs"] == Decimal("20")
    assert channels["site"]["contribution_margin"] == Decimal("360")
    assert channels["unattributed"]["additional_costs"] == Decimal("50")
    assert len(result["stock"]) == 2
    main = next(
        item for item in result["stock"] if item["warehouse_external_id"] == "main"
    )
    assert main["quantity"] == Decimal("7")
    assert main["available"] == Decimal("6")