package artifacts

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

	"github.com/novox/mesh-controller/internal/catalogue"
)

// Asking the store to let go of what the mesh no longer keeps (novox/hq ADR 0189, issue 108).
//
// A fake store records what it was asked to delete, so what is asserted is the mesh's decision
// and the shape of the request — not the registry's behaviour, which is the registry's to test.

func fakeStore(t *testing.T, answer int) (Store, *[]string) {
	t.Helper()
	var asked []string
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodDelete {
			t.Errorf("the store was asked %s %s; collecting is a delete", r.Method, r.URL.Path)
		}
		asked = append(asked, r.URL.Path)
		w.WriteHeader(answer)
	}))
	t.Cleanup(server.Close)
	return Store{Address: strings.TrimPrefix(server.URL, "http://")}, &asked
}

func TestAnImageAndAnArchiveAreAskedForAtTheirOwnEndpoints(t *testing.T) {
	// The two shapes the mesh records: a manifest by digest, and a blob by digest. They are
	// different endpoints, and asking at the wrong one answers 404 — which this would then
	// record as collected, leaving the bytes on disk for ever while the record says otherwise.
	store, asked := fakeStore(t, http.StatusAccepted)
	ctx := context.Background()

	image := catalogue.ArtifactStoreScheme + "web/app@sha256:abc123"
	archive := catalogue.ArtifactStoreScheme + "web/config/blobs/sha256:def456"
	if err := store.LetGo(ctx, image); err != nil {
		t.Fatal(err)
	}
	if err := store.LetGo(ctx, archive); err != nil {
		t.Fatal(err)
	}
	want := []string{"/v2/web/app/manifests/sha256:abc123", "/v2/web/config/blobs/sha256:def456"}
	if len(*asked) != 2 || (*asked)[0] != want[0] || (*asked)[1] != want[1] {
		t.Fatalf("the store was asked %v; want %v", *asked, want)
	}
}

func TestAStoreThatDoesNotHaveItAnswersGone(t *testing.T) {
	// The outcome wanted, already true. Told apart from success only so the sweep can say which
	// happened; both are recorded, because retrying for ever is the thing to avoid.
	store, _ := fakeStore(t, http.StatusNotFound)
	err := store.LetGo(context.Background(), catalogue.ArtifactStoreScheme+"web/app@sha256:abc123")
	if !errors.Is(err, Gone) {
		t.Fatalf("a store that does not hold it answered %v, want Gone", err)
	}
}

func TestAStoreWithDeletionOffSaysSoAndNamesTheRemedy(t *testing.T) {
	// The registry answers 405 when it was started without deletion enabled. The remedy is a
	// setting on the store's module, and saying "405" would send somebody to the wrong place.
	store, _ := fakeStore(t, http.StatusMethodNotAllowed)
	err := store.LetGo(context.Background(), catalogue.ArtifactStoreScheme+"web/app@sha256:abc123")
	if err == nil {
		t.Fatal("a store that refuses deletion was read as success")
	}
	if !strings.Contains(err.Error(), "REGISTRY_STORAGE_DELETE_ENABLED") {
		t.Fatalf("the refusal does not name the remedy: %v", err)
	}
}

func TestAReferenceThatIsNotTheMeshsOwnIsNeverAsked(t *testing.T) {
	// The whole safety of the sweep is that it names only what the mesh recorded putting there.
	// A reference of another shape — a vendor's image, a package version — is refused rather
	// than composed into a delete somewhere that is not the mesh's store.
	store, asked := fakeStore(t, http.StatusAccepted)
	for _, reference := range []string{
		"docker.io/library/registry@sha256:abc123",
		"registry@sha256:abc123",
		"1.4.2",
	} {
		if err := store.LetGo(context.Background(), reference); err == nil {
			t.Errorf("%s was asked about; it is not a reference into the mesh's store", reference)
		}
	}
	if len(*asked) != 0 {
		t.Fatalf("the store was asked about %v", *asked)
	}
}

// A reference this sweep will not address says so as ErrNotOurs, which is a fact about the
// record and not about the store (novox/hq issue 226).
//
// The sweep skips one and abandons itself for the other, so they cannot be the same error. The
// first live run met a reference recorded with the store's old address, read the refusal as "the
// store refuses everything", and collected none of the 1681 it had found.
func TestAReferenceThisSweepWillNotAddressIsToldApartFromAStoreRefusing(t *testing.T) {
	store, asked := fakeStore(t, http.StatusAccepted)
	for _, reference := range []string{
		"docker.io/library/registry@sha256:abc123",
		"127.0.0.1:5100/mesh-tools/build@sha256:abc123",
		"1.4.2",
	} {
		err := store.LetGo(context.Background(), reference)
		if !errors.Is(err, ErrNotOurs) {
			t.Errorf("%s answered %v; a sweep must be able to skip it and go on", reference, err)
		}
	}
	if len(*asked) != 0 {
		t.Fatalf("the store was asked about %v", *asked)
	}
}