package services

import (
	"testing"

	"nearle/models"
	"nearle/repositories"
)

/*
The rule these tests defend, read off the customer app's own query
(`repositories/productRepository.go` GetProducts and
`controllers/productController.go` GetProductsBySubcategory):

	SELECT ... FROM products a
	LEFT JOIN productlocations pl ON pl.productid = a.productid AND pl.tenantid = a.tenantid
	WHERE a.categoryid = ?        -- and the controller rejects 0 outright
	  AND pl.locationid = ?       -- so the LEFT JOIN behaves as an inner one

A product is therefore visible to a shopper only when BOTH hold: it has a
non-zero category, and it has a productlocations row at that outlet. Nothing
else gates it — not `approved`, not `publishedat`, not `productstatus`, not the
stock level.

Both conditions were reachable states that no API could produce or repair, and
a sweep of all 262 tenants found 7 products and 6 outlets already in them —
outlets showing an empty shop while the console listed their stock.
*/

// fakeProductRepo records calls in order. The interface is large, so it is
// embedded rather than implemented: anything these tests do not exercise is nil
// and panics loudly if the code under test starts depending on it, which is the
// failure we want rather than a silent zero value.
type fakeProductRepo struct {
	repositories.ProductRepository

	calls []string

	existing *models.Products

	ensuredRefs []models.ProductLocationRef
	syncedRefs  []models.ProductLocationRef
	categorySet map[int][2]int // productid -> {categoryid, subcategoryid}
}

func newFakeRepo() *fakeProductRepo {
	return &fakeProductRepo{categorySet: map[int][2]int{}}
}

func (f *fakeProductRepo) CreateProductStock(stocks []models.Productstock) error {
	f.calls = append(f.calls, "CreateProductStock")
	return nil
}

func (f *fakeProductRepo) EnsureProductLocation(refs []models.ProductLocationRef) error {
	f.calls = append(f.calls, "EnsureProductLocation")
	f.ensuredRefs = append(f.ensuredRefs, refs...)
	return nil
}

func (f *fakeProductRepo) SyncProductLocationStatus(refs []models.ProductLocationRef) error {
	f.calls = append(f.calls, "SyncProductLocationStatus")
	f.syncedRefs = append(f.syncedRefs, refs...)
	return nil
}

func (f *fakeProductRepo) FindTenantProductByCatalogueRef(tenantid int, brand string, catalogueid int64) (*models.Products, error) {
	f.calls = append(f.calls, "FindTenantProductByCatalogueRef")
	return f.existing, nil
}

func (f *fakeProductRepo) UpdateProductPricing(productid int, retailprice, productcost, taxpercent float64) error {
	f.calls = append(f.calls, "UpdateProductPricing")
	return nil
}

func (f *fakeProductRepo) UpdateProductCategory(productid, categoryid, subcategoryid int) error {
	f.calls = append(f.calls, "UpdateProductCategory")
	// Mirrors the real implementation's guard so the tests exercise the same
	// rule the database would.
	if categoryid <= 0 {
		return nil
	}
	f.categorySet[productid] = [2]int{categoryid, subcategoryid}
	return nil
}

func (f *fakeProductRepo) CreateProductLocation(input []models.Productlocations) error {
	f.calls = append(f.calls, "CreateProductLocation")
	return nil
}

// fakeCatalogueService returns one fixed catalogue product.
type fakeCatalogueService struct {
	CatalogueService
	product *models.CatalogueProduct
}

func (f *fakeCatalogueService) GetProductByID(brand string, id int64) (*models.CatalogueProduct, error) {
	return f.product, nil
}

func indexOf(calls []string, want string) int {
	for i, c := range calls {
		if c == want {
			return i
		}
	}
	return -1
}

// The end-to-end requirement, at the point it was broken: request a product,
// approve it, receive the stock — and the shopper can buy it.
//
// Receiving used to write the stock ledger and then call
// SyncProductLocationStatus, which is an UPDATE. At an outlet with no
// productlocations row it updated nothing and returned success, so the console
// showed the stock climbing and the app never listed the product.
func TestReceivingStockPutsTheProductOnTheOutletsShelf(t *testing.T) {
	repo := newFakeRepo()
	svc := NewProductService(repo, &fakeCatalogueService{})

	err := svc.CreateProductStock([]models.Productstock{{
		Tenantid:   1135,
		Locationid: 1170,
		Productid:  7086,
		Quantity:   25,
		Stocktype:  "in",
	}})
	if err != nil {
		t.Fatalf("CreateProductStock: %v", err)
	}

	if len(repo.ensuredRefs) != 1 {
		t.Fatalf("the product was never shelved: EnsureProductLocation saw %d refs, want 1", len(repo.ensuredRefs))
	}
	got := repo.ensuredRefs[0]
	if got.Tenantid != 1135 || got.Locationid != 1170 || got.Productid != 7086 {
		t.Errorf("shelved the wrong row: %+v", got)
	}
}

// Order matters and is not incidental.
//
// EnsureProductLocation seeds the new row "outofstock" because that is true at
// the instant of the insert. SyncProductLocationStatus then derives the real
// value from the ledger. Run the other way round, a genuine receipt would leave
// a freshly created row reading "outofstock" until the NEXT delivery.
func TestTheShelfIsCreatedBeforeAvailabilityIsDerived(t *testing.T) {
	repo := newFakeRepo()
	svc := NewProductService(repo, &fakeCatalogueService{})

	if err := svc.CreateProductStock([]models.Productstock{{
		Tenantid: 1135, Locationid: 1170, Productid: 7086, Quantity: 25, Stocktype: "in",
	}}); err != nil {
		t.Fatalf("CreateProductStock: %v", err)
	}

	ensure := indexOf(repo.calls, "EnsureProductLocation")
	sync := indexOf(repo.calls, "SyncProductLocationStatus")
	if ensure < 0 || sync < 0 {
		t.Fatalf("expected both calls, got %v", repo.calls)
	}
	if ensure > sync {
		t.Errorf("EnsureProductLocation must run before SyncProductLocationStatus, got %v", repo.calls)
	}
}

// An "out" movement must shelve the product too.
//
// The location row is what makes the product addressable at all, so a sale
// recorded at an outlet that somehow has no row should create it and then be
// correctly derived as outofstock — not be silently dropped.
func TestAnOutwardMovementAlsoShelves(t *testing.T) {
	repo := newFakeRepo()
	svc := NewProductService(repo, &fakeCatalogueService{})

	if err := svc.CreateProductStock([]models.Productstock{{
		Tenantid: 1135, Locationid: 1170, Productid: 7086, Quantity: 3, Stocktype: "out",
	}}); err != nil {
		t.Fatalf("CreateProductStock: %v", err)
	}
	if len(repo.ensuredRefs) != 1 {
		t.Fatalf("an out movement did not shelve: %v", repo.calls)
	}
}

// Re-importing is the repair path for a product stuck at categoryid 0, and
// until now it silently was not: the existing-product branch corrected pricing
// and nothing else, so the obvious fix appeared to work and changed nothing.
func TestReimportingCorrectsAnUncategorisedProduct(t *testing.T) {
	repo := newFakeRepo()
	repo.existing = &models.Products{Productid: 7086, Tenantid: 1135, Categoryid: 0}
	svc := NewProductService(repo, &fakeCatalogueService{
		product: &models.CatalogueProduct{ID: 42, Brand: "cadbury", ProductName: "Cadbury Dairy Milk 100g"},
	})

	err := svc.ImportCatalogueProduct([]models.ImportCatalogueProductRequest{{
		Tenantid: 1135, Locationid: 1170, Brand: "cadbury", Catalogueid: 42,
		Categoryid: 2, Retailprice: 50,
	}})
	if err != nil {
		t.Fatalf("ImportCatalogueProduct: %v", err)
	}

	got, ok := repo.categorySet[7086]
	if !ok {
		t.Fatalf("re-import did not touch the category; calls were %v", repo.calls)
	}
	if got[0] != 2 {
		t.Errorf("categoryid = %d, want 2", got[0])
	}
}

// The correction must never run backwards. An import that omits the category
// has nothing to say about it, and writing 0 would create exactly the invisible
// state this whole change exists to remove.
func TestReimportWithoutACategoryLeavesTheExistingOneAlone(t *testing.T) {
	repo := newFakeRepo()
	repo.existing = &models.Products{Productid: 7043, Tenantid: 1135, Categoryid: 2}
	svc := NewProductService(repo, &fakeCatalogueService{
		product: &models.CatalogueProduct{ID: 9, Brand: "generic", ProductName: "Apple"},
	})

	err := svc.ImportCatalogueProduct([]models.ImportCatalogueProductRequest{{
		Tenantid: 1135, Locationid: 1170, Brand: "generic", Catalogueid: 9,
		Categoryid: 0, Retailprice: 120,
	}})
	if err != nil {
		t.Fatalf("ImportCatalogueProduct: %v", err)
	}

	if _, overwritten := repo.categorySet[7043]; overwritten {
		t.Errorf("a category-less import overwrote an existing category")
	}
}

/*
"If we have the stock, we can order it" — the customer app's browse rule.

The products below are Suriya Store's Peelamedu shelf as it actually stood:
three products listed, one with stock. Before this filter the app offered all
three, so a shopper could order two chocolate bars the shop did not have.
*/

func names(products []models.Products) []string {
	out := make([]string, 0, len(products))
	for _, p := range products {
		out = append(out, p.Productname)
	}
	return out
}

var peelamedu = []models.Products{
	{Productid: 7084, Productname: "Cadbury 5 Star 9.8 g", Productstock: 0},
	{Productid: 7085, Productname: "Cadbury 5 Star 18g", Productstock: 0},
	{Productid: 7086, Productname: "Cadbury Dairy Milk 100g", Productstock: 25},
}

func TestOnlyProductsWithStockAreOffered(t *testing.T) {
	got := InStockOnly(peelamedu, 1170)

	if len(got) != 1 {
		t.Fatalf("offered %d products, want 1: %v", len(got), names(got))
	}
	if got[0].Productid != 7086 {
		t.Errorf("offered %d, want 7086 (the only one in stock)", got[0].Productid)
	}
}

// An outlet with nothing in stock offers nothing — it does not fall back to
// showing the shelf. An empty shop is the honest answer.
func TestAnOutletWithNoStockOffersNothing(t *testing.T) {
	empty := []models.Products{
		{Productid: 7084, Productstock: 0},
		{Productid: 7085, Productstock: 0},
	}
	if got := InStockOnly(empty, 1172); len(got) != 0 {
		t.Errorf("offered %d products from an empty shelf", len(got))
	}
}

// Without an outlet, GetProducts scopes its balance subquery to locationid 0,
// which matches nothing and returns every product with Productstock 0. Filtering
// there would empty the catalogue instead of leaving it unscoped.
func TestAnUnscopedBrowseIsNotFiltered(t *testing.T) {
	if got := InStockOnly(peelamedu, 0); len(got) != 3 {
		t.Errorf("unscoped browse returned %d, want all 3 unfiltered", len(got))
	}
}

// A negative balance is not stock. The ledger can go below zero when an "out"
// exceeds what was received, and `> 0` must not read that as sellable.
func TestANegativeBalanceIsNotStock(t *testing.T) {
	oversold := []models.Products{{Productid: 7084, Productstock: -3}}
	if got := InStockOnly(oversold, 1170); len(got) != 0 {
		t.Errorf("an oversold product was offered for sale")
	}
}

func TestFilteringDoesNotDisturbTheCallersSlice(t *testing.T) {
	source := []models.Products{
		{Productid: 1, Productstock: 0},
		{Productid: 2, Productstock: 5},
	}
	_ = InStockOnly(source, 1170)
	if len(source) != 2 || source[0].Productid != 1 || source[1].Productid != 2 {
		t.Errorf("the input slice was modified: %+v", source)
	}
}

func (f *fakeProductRepo) GetSubcategories(categoryID int) ([]models.Subcategory, error) {
	return nil, nil
}

// Returns (nil, nil) so GetProductsBySubcategory falls through to its plain
// {"details": ...} shape. The tenant header block is not what this test is about.
func (f *fakeProductRepo) GetTenantInfo(tenantID, applocationID int) (map[string]interface{}, error) {
	return nil, nil
}

func (f *fakeProductRepo) GetProducts(params models.ProductFilter) ([]models.Products, error) {
	f.calls = append(f.calls, "GetProducts")
	return peelamedu, nil
}

// The filter has to be WIRED, not merely written.
//
// The tests above exercise InStockOnly directly, which would keep passing if
// nobody called it. This goes through the endpoint the customer app actually
// hits and asserts on what a shopper would be shown.
func TestTheBrowseEndpointOffersOnlyStockedProducts(t *testing.T) {
	repo := newFakeRepo()
	svc := NewProductService(repo, &fakeCatalogueService{})

	result, err := svc.GetProductsBySubcategory(models.ProductFilter{
		CategoryID: 2, TenantID: 1135, LocationID: 1170,
	})
	if err != nil {
		t.Fatalf("GetProductsBySubcategory: %v", err)
	}

	groups, _ := result["details"].([]models.SubcategoryProductResponse)
	var offered []models.Products
	for _, g := range groups {
		offered = append(offered, g.Products...)
	}

	if len(offered) != 1 {
		t.Fatalf("the app was offered %d products, want 1: %v", len(offered), names(offered))
	}
	if offered[0].Productid != 7086 {
		t.Errorf("offered product %d, want 7086 — the only one Peelamedu has", offered[0].Productid)
	}
}