package mock

import (
	"math/rand"
	"os"
	"strings"
	"testing"
)

// loadTestCatalog parses the small fixture catalog used by the tests.
func loadTestCatalog(t *testing.T) *Catalog {
	t.Helper()
	b, err := os.ReadFile("testdata/catalog.json")
	if err != nil {
		t.Fatal(err)
	}
	cat, err := parseCatalog(b, "testdata/catalog.json")
	if err != nil {
		t.Fatal(err)
	}
	return cat
}

// The catalog compiled into the build must load: a bad data/catalog.json
// fails here rather than when the mock starts.
func TestEmbeddedCatalogIsValid(t *testing.T) {
	if len(embeddedCatalog) == 0 {
		t.Fatal("data/catalog.json was not embedded")
	}
	cat, err := LoadCatalog()
	if err != nil {
		t.Fatal(err)
	}
	if len(cat.Buyers) == 0 || len(cat.Suppliers) == 0 ||
		len(cat.Subjects) == 0 || len(cat.Methods) == 0 {
		t.Fatalf(
			"embedded catalog has an empty pool: %d buyers, %d suppliers, %d subjects, %d methods",
			len(cat.Buyers),
			len(cat.Suppliers),
			len(cat.Subjects),
			len(cat.Methods),
		)
	}
}

func TestParseCatalog(t *testing.T) {
	cat := loadTestCatalog(t)
	if len(cat.Buyers) != 2 || len(cat.Suppliers) != 1 ||
		len(cat.Subjects) != 2 || len(cat.Methods) != 2 {
		t.Fatalf(
			"got %d buyers, %d suppliers, %d subjects, %d methods",
			len(cat.Buyers),
			len(cat.Suppliers),
			len(cat.Subjects),
			len(cat.Methods),
		)
	}

	if d := cat.Buyers[0].Details; d == nil || len(d.Classifications) != 1 ||
		d.Classifications[0].Scheme != "UK_CA_TYPE" {
		t.Fatalf("buyer details.classifications not read: %+v", d)
	}

	s := cat.Subjects[0]
	if s.Classification != "CPV-77314000" || len(s.Items) != 1 {
		t.Fatalf("subject classification key/items not read: %+v", s)
	}
	if ac := s.Items[0].AdditionalClassifications; len(ac) != 1 ||
		ac[0] != "CPV-77310000" {
		t.Fatalf("items.additionalClassifications keys not read: %+v", ac)
	}
	if v := s.Lots[0].Value; v == nil || v.AmountGross == nil ||
		*v.AmountGross != 120000 {
		t.Fatalf("lot value not read: %+v", v)
	}
}

// Picking a subject resolves its classification keys to full classifications.
func TestSubjectResolvesClassifications(t *testing.T) {
	cat := loadTestCatalog(t)
	//nolint:gosec // G404: seeded math/rand keeps the test deterministic
	r := rand.New(rand.NewSource(1))
	for i := 0; i < 20; i++ {
		tender := cat.subject(r)
		if tender.Title != "Grounds maintenance services" {
			continue
		}
		if cl := tender.Classification; cl == nil || cl.ID != "77314000" ||
			cl.Description != "Grounds maintenance services" {
			t.Fatalf("main classification = %+v", cl)
		}
		ac := tender.Items[0].AdditionalClassifications
		if len(ac) != 1 ||
			ac[0].Description != "Planting and maintenance services of green areas" {
			t.Fatalf("item classifications = %+v", ac)
		}
		// The catalog itself still holds keys, untouched by picking.
		if cat.Subjects[0].Classification != "CPV-77314000" {
			t.Fatal("picking modified the catalog")
		}
		return
	}
	t.Fatal("never picked the grounds maintenance subject")
}

func TestParseCatalogRejectsInvalidCatalogs(t *testing.T) {
	cases := map[string]struct {
		doc  string
		want []string
	}{
		"empty pools": {
			doc:  `{"buyers": [], "subjects": [{"title": "T"}], "methods": [], "classifications": {}}`,
			want: []string{"no buyers", "no suppliers", "no methods"},
		},
		"unknown classification keys": {
			doc: `{"buyers": [{"name": "B"}], "suppliers": [{"name": "S"}], "methods": [{"procurementMethod": "open"}],
				"subjects": [{"title": "T", "classification": "CPV-1", "items": [{"id": "1", "additionalClassifications": ["CPV-2"]}]}],
				"classifications": {}}`,
			want: []string{"2 classification key(s) not found", "CPV-1", "CPV-2"},
		},
		"not JSON": {doc: `{`, want: []string{"decoding"}},
	}
	for name, tc := range cases {
		t.Run(name, func(t *testing.T) {
			_, err := parseCatalog([]byte(tc.doc), "test catalog")
			if err == nil {
				t.Fatal("expected an error")
			}
			for _, w := range tc.want {
				if !strings.Contains(err.Error(), w) {
					t.Errorf("error %q does not mention %q", err, w)
				}
			}
		})
	}
}

func TestResolveOneUnknownKey(t *testing.T) {
	cat := loadTestCatalog(t)
	if cl := cat.resolveOne("CPV-00000000"); cl != nil {
		t.Errorf("unknown key resolved to %+v", cl)
	}
	if cl := cat.resolveOne(""); cl != nil {
		t.Errorf("empty key resolved to %+v", cl)
	}
	if got := cat.resolve([]string{"CPV-00000000"}); got != nil {
		t.Errorf("resolve of unknown keys = %+v", got)
	}
}