package inventory

import (
	"context"
	"errors"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
)

type mockStockReader struct {
	stock map[string]int64
	err   error
}

func (m *mockStockReader) GetInventory(ctx context.Context, sku SKU, locationID LocationID) (int64, error) {
	if m.err != nil {
		return 0, m.err
	}
	qty, ok := m.stock[string(sku)]
	if !ok {
		return 0, errors.New("sku not found")
	}
	return qty, nil
}

func TestBadgeHandler(t *testing.T) {
	mock := &mockStockReader{
		stock: map[string]int64{
			"HIGH": 25,
			"LOW":  3,
			"OUT":  0,
		},
	}

	handler := BadgeHandler(mock)

	tests := []struct {
		name           string
		url            string
		expectedCode   int
		expectedSubstr string
	}{
		{
			name:           "missing sku",
			url:            "/inventory/badge",
			expectedCode:   http.StatusBadRequest,
			expectedSubstr: "missing sku parameter",
		},
		{
			name:           "high stock",
			url:            "/inventory/badge?sku=HIGH",
			expectedCode:   http.StatusOK,
			expectedSubstr: "stock-in-stock",
		},
		{
			name:           "low stock",
			url:            "/inventory/badge?sku=LOW",
			expectedCode:   http.StatusOK,
			expectedSubstr: "Only 3 left!",
		},
		{
			name:           "out of stock",
			url:            "/inventory/badge?sku=OUT",
			expectedCode:   http.StatusOK,
			expectedSubstr: "stock-out-of-stock",
		},
		{
			name:           "unknown stock / error",
			url:            "/inventory/badge?sku=UNKNOWN",
			expectedCode:   http.StatusOK,
			expectedSubstr: "stock-unknown",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			req := httptest.NewRequest(http.MethodGet, tt.url, nil)
			rr := httptest.NewRecorder()

			handler.ServeHTTP(rr, req)

			if rr.Code != tt.expectedCode {
				t.Errorf("expected status code %d, got %d", tt.expectedCode, rr.Code)
			}

			body := rr.Body.String()
			if !strings.Contains(body, tt.expectedSubstr) {
				t.Errorf("expected body to contain %q, got %q", tt.expectedSubstr, body)
			}
		})
	}
}