package gitea

import (
	"context"
	"encoding/json"
	"errors"
	"io"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"

	"go.maximumdirect.net/releasekit/internal/forge"
)

func TestBackendTagCommitUsesEscapedFullTagAndAuthentication(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if got, want := r.RequestURI, "/api/v1/repos/owner/project/tags/v1.2.3%2Frc.1"; got != want {
			t.Errorf("request URI = %q, want %q", got, want)
		}
		if got, want := r.Header.Get("Authorization"), "token fixture-secret-token"; got != want {
			t.Errorf("authorization = %q, want %q", got, want)
		}
		_ = json.NewEncoder(w).Encode(map[string]any{"commit": map[string]string{"sha": "abcdef"}})
	}))
	defer server.Close()

	backend := NewBackend(testDestination(server.URL), server.Client())
	commit, err := backend.TagCommit(context.Background(), "v1.2.3/rc.1")
	if err != nil || commit != "abcdef" {
		t.Fatalf("TagCommit() = %q, %v", commit, err)
	}
}

func TestBackendFindReleaseReturnsNeutralNotFound(t *testing.T) {
	server := httptest.NewServer(http.NotFoundHandler())
	defer server.Close()
	backend := NewBackend(testDestination(server.URL), server.Client())

	_, err := backend.FindRelease(context.Background(), "v1.2.3")
	var failure *forge.Failure
	if !errors.As(err, &failure) || failure.Kind != forge.FailureNotFound {
		t.Fatalf("FindRelease() error = %v, want neutral not-found failure", err)
	}
	var cause *Failure
	if !errors.As(err, &cause) || cause.StatusCode != http.StatusNotFound {
		t.Fatalf("FindRelease() error cause = %v, want Gitea 404 diagnostic", err)
	}
}

func TestBackendFindReleaseDoesNotRequireWriteResponseFields(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		_ = json.NewEncoder(w).Encode(releaseResponse{TagName: "v1.2.3", Name: "Release"})
	}))
	defer server.Close()
	backend := NewBackend(testDestination(server.URL), server.Client())

	release, err := backend.FindRelease(context.Background(), "v1.2.3")
	if err != nil {
		t.Fatal(err)
	}
	if release.Tag != "v1.2.3" || release.Title != "Release" || release.Handle == nil {
		t.Fatalf("FindRelease() = %#v", release)
	}
}

func TestBackendAssetOperationsRequireObservedReleaseID(t *testing.T) {
	for _, tc := range []struct {
		name, body string
		valid      bool
	}{
		{"missing", `{"tag_name":"v1.2.3"}`, false},
		{"zero", `{"id":0,"tag_name":"v1.2.3"}`, false},
		{"negative", `{"id":-1,"tag_name":"v1.2.3"}`, false},
		{"valid", `{"id":12,"tag_name":"v1.2.3"}`, true},
	} {
		t.Run(tc.name, func(t *testing.T) {
			requests := 0
			server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
				if strings.Contains(r.URL.Path, "/releases/tags/") {
					_, _ = io.WriteString(w, tc.body)
					return
				}
				requests++
				if r.Method == http.MethodGet {
					_, _ = io.WriteString(w, `[]`)
					return
				}
				w.WriteHeader(http.StatusCreated)
				_, _ = io.WriteString(w, `{"id":1,"name":"file"}`)
			}))
			defer server.Close()
			backend := NewBackend(testDestination(server.URL), server.Client())
			release, err := backend.FindRelease(context.Background(), "v1.2.3")
			if err != nil {
				t.Fatal(err)
			}
			_, listErr := backend.ListAssets(context.Background(), release.Handle)
			evidence, uploadErr := backend.UploadAsset(context.Background(), release.Handle, "file", strings.NewReader("data"))
			if tc.valid {
				if listErr != nil || uploadErr != nil || requests != 2 {
					t.Fatalf("valid: list %v, upload %v, requests %d", listErr, uploadErr, requests)
				}
				return
			}
			for _, err := range []error{listErr, uploadErr} {
				var failure *forge.Failure
				if !errors.As(err, &failure) || failure.Kind != forge.FailureMalformed {
					t.Fatalf("failure = %v", err)
				}
			}
			if requests != 0 || evidence.Attempted || evidence.Disposition != forge.WriteNotAttempted {
				t.Fatalf("requests = %d, evidence = %#v", requests, evidence)
			}
		})
	}
	backend := NewBackend(Destination{}, nil)
	_, listErr := backend.ListAssets(context.Background(), "wrong")
	evidence, uploadErr := backend.UploadAsset(context.Background(), "wrong", "file", strings.NewReader("data"))
	for _, err := range []error{listErr, uploadErr} {
		var failure *forge.Failure
		if !errors.As(err, &failure) || failure.Kind != forge.FailureInvalid {
			t.Fatalf("wrong handle failure = %v", err)
		}
	}
	if evidence.Attempted || evidence.Disposition != forge.WriteNotAttempted {
		t.Fatalf("wrong handle evidence = %#v", evidence)
	}
}

func TestBackendListsMetadataAndOpensCallerOwnedAssetStream(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if got, want := r.Header.Get("Authorization"), "token fixture-secret-token"; got != want {
			t.Errorf("authorization = %q, want %q", got, want)
		}
		switch r.URL.Path {
		case "/api/v1/repos/owner/project/releases/tags/v1.2.3":
			_ = json.NewEncoder(w).Encode(releaseResponse{ID: 12, TagName: "v1.2.3"})
		case "/api/v1/repos/owner/project/releases/12/assets":
			_ = json.NewEncoder(w).Encode([]assetResponse{{ID: 4, Name: "app.bin", Size: 4, BrowserDownloadURL: "/files/app"}})
		case "/files/app":
			_, _ = io.WriteString(w, "data")
		default:
			t.Errorf("unexpected path %q", r.URL.Path)
			http.NotFound(w, r)
		}
	}))
	defer server.Close()
	backend := NewBackend(testDestination(server.URL), server.Client())

	release, err := backend.FindRelease(context.Background(), "v1.2.3")
	if err != nil {
		t.Fatal(err)
	}
	assets, err := backend.ListAssets(context.Background(), release.Handle)
	if err != nil {
		t.Fatal(err)
	}
	if len(assets) != 1 || assets[0].Filename != "app.bin" || assets[0].Size != 4 || assets[0].Handle == nil {
		t.Fatalf("ListAssets() = %#v", assets)
	}
	stream, err := backend.OpenAsset(context.Background(), assets[0].Handle)
	if err != nil {
		t.Fatal(err)
	}
	content, readErr := io.ReadAll(stream)
	closeErr := stream.Close()
	if readErr != nil || closeErr != nil || string(content) != "data" {
		t.Fatalf("OpenAsset() content = %q, read error = %v, close error = %v", content, readErr, closeErr)
	}
}

func TestBackendRejectsAssetHandleFromAnotherBackendType(t *testing.T) {
	backend := NewBackend(testDestination("http://example.test"), nil)
	_, err := backend.OpenAsset(context.Background(), strings.NewReader("asset"))
	var failure *forge.Failure
	if !errors.As(err, &failure) || failure.Kind != forge.FailureInvalid {
		t.Fatalf("OpenAsset() error = %v, want invalid handle", err)
	}
}

func TestBackendPreflightUsesAuthenticatedRepositoryReadsAndIgnoresCodePushPermission(t *testing.T) {
	var requests []string
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodGet {
			t.Errorf("method = %q, want GET", r.Method)
		}
		if got, want := r.Header.Get("Authorization"), "token fixture-secret-token"; got != want {
			t.Errorf("authorization = %q, want %q", got, want)
		}
		requests = append(requests, r.URL.Path)
		writeRepository := func() {
			_ = json.NewEncoder(w).Encode(map[string]any{
				"id": 31, "name": "project", "full_name": "owner/project",
				"owner":       map[string]string{"login": "owner"},
				"permissions": map[string]bool{"admin": false, "push": false, "pull": true},
			})
		}
		switch r.URL.Path {
		case "/api/v1/repos/owner/project", "/api/v1/repositories/31":
			writeRepository()
		default:
			t.Errorf("unexpected path %q", r.URL.Path)
			http.NotFound(w, r)
		}
	}))
	defer server.Close()

	if err := NewBackend(testDestination(server.URL), server.Client()).Preflight(context.Background()); err != nil {
		t.Fatal(err)
	}
	if len(requests) != 2 || requests[0] != "/api/v1/repos/owner/project" || requests[1] != "/api/v1/repositories/31" {
		t.Fatalf("preflight requests = %v, want both repository reads", requests)
	}
}

func TestBackendPreflightRequiresCredentialWithoutMakingRequests(t *testing.T) {
	var requests int
	server := httptest.NewServer(http.HandlerFunc(func(http.ResponseWriter, *http.Request) { requests++ }))
	defer server.Close()
	destination := testDestination(server.URL)
	destination.Token = " \t"

	err := NewBackend(destination, server.Client()).Preflight(context.Background())
	var failure *forge.PreflightFailure
	if !errors.As(err, &failure) || failure.Kind != forge.PreflightMissingCredential {
		t.Fatalf("Preflight() error = %v, want missing credential", err)
	}
	if requests != 0 {
		t.Fatalf("made %d requests without a credential", requests)
	}
}

func TestBackendPreflightDoesNotAcceptPublicLookupWithoutAuthenticatedAccess(t *testing.T) {
	var requests []string
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		requests = append(requests, r.URL.Path)
		if r.URL.Path == "/api/v1/repos/owner/project" {
			_ = json.NewEncoder(w).Encode(map[string]any{"id": 31, "name": "project", "full_name": "owner/project", "owner": map[string]string{"login": "owner"}})
			return
		}
		http.Error(w, "token rejected", http.StatusUnauthorized)
	}))
	defer server.Close()

	err := NewBackend(testDestination(server.URL), server.Client()).Preflight(context.Background())
	var failure *forge.PreflightFailure
	if !errors.As(err, &failure) || failure.Kind != forge.PreflightInvalidCredential {
		t.Fatalf("Preflight() error = %v, want invalid credential", err)
	}
	if len(requests) != 2 || requests[1] != "/api/v1/repositories/31" {
		t.Fatalf("preflight requests = %v, want authenticated repository read", requests)
	}
	if strings.Contains(err.Error(), testDestination(server.URL).Token) {
		t.Fatalf("preflight error exposed the credential: %v", err)
	}
}

func TestBackendPreflightClassifiesDeniedAndHiddenRepositoriesAsInaccessible(t *testing.T) {
	for _, status := range []int{http.StatusForbidden, http.StatusNotFound} {
		t.Run(http.StatusText(status), func(t *testing.T) {
			server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
				http.Error(w, "repository unavailable", status)
			}))
			defer server.Close()

			err := NewBackend(testDestination(server.URL), server.Client()).Preflight(context.Background())
			var failure *forge.PreflightFailure
			if !errors.As(err, &failure) || failure.Kind != forge.PreflightInaccessibleDestination {
				t.Fatalf("Preflight() error = %v, want inaccessible destination", err)
			}
		})
	}
}

func TestBackendPreflightClassifiesUnverifiableResponsesAsUnavailable(t *testing.T) {
	for _, test := range []struct {
		name    string
		respond func(http.ResponseWriter)
	}{
		{name: "malformed JSON", respond: func(w http.ResponseWriter) { _, _ = io.WriteString(w, "{") }},
		{name: "service failure", respond: func(w http.ResponseWriter) { http.Error(w, "temporarily unavailable", http.StatusServiceUnavailable) }},
		{name: "wrong repository identity", respond: func(w http.ResponseWriter) {
			_ = json.NewEncoder(w).Encode(map[string]any{"id": 31, "name": "other", "full_name": "owner/other", "owner": map[string]string{"login": "owner"}})
		}},
	} {
		t.Run(test.name, func(t *testing.T) {
			server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { test.respond(w) }))
			defer server.Close()

			err := NewBackend(testDestination(server.URL), server.Client()).Preflight(context.Background())
			var failure *forge.PreflightFailure
			if !errors.As(err, &failure) || failure.Kind != forge.PreflightUnavailable {
				t.Fatalf("Preflight() error = %v, want unavailable", err)
			}
		})
	}
}

func TestBackendPreflightPreservesCancellation(t *testing.T) {
	server := httptest.NewServer(http.NotFoundHandler())
	defer server.Close()
	ctx, cancel := context.WithCancel(context.Background())
	cancel()

	err := NewBackend(testDestination(server.URL), server.Client()).Preflight(ctx)
	var failure *forge.PreflightFailure
	if !errors.As(err, &failure) || failure.Kind != forge.PreflightUnavailable || !errors.Is(err, context.Canceled) {
		t.Fatalf("Preflight() error = %v, want unavailable and context cancellation", err)
	}
}

func TestBackendCreateReleaseSendsRequestedFieldsAndAcceptsProtocolAcknowledgment(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost || r.URL.Path != "/api/v1/repos/owner/project/releases" {
			t.Errorf("request = %s %s", r.Method, r.URL.Path)
		}
		if got, want := r.Header.Get("Authorization"), "token fixture-secret-token"; got != want {
			t.Errorf("authorization = %q, want %q", got, want)
		}
		var request createReleaseRequest
		if err := json.NewDecoder(r.Body).Decode(&request); err != nil {
			t.Errorf("decode request: %v", err)
		}
		if request.TagName != "v1.2.3" || request.TargetCommitish != strings.Repeat("a", 40) || request.Name != "Release title" || request.Body != "# Release title\n\nComplete notes." || !request.Draft || !request.Prerelease {
			t.Errorf("release request = %#v", request)
		}
		_ = json.NewEncoder(w).Encode(releaseResponse{ID: 12, TagName: "server tag", Name: "server title", Body: "server body", Draft: true, Prerelease: true})
	}))
	defer server.Close()
	backend := NewBackend(testDestination(server.URL), server.Client())

	release, evidence, err := backend.CreateRelease(context.Background(), forge.CreateReleaseRequest{
		Tag: "v1.2.3", Commit: strings.Repeat("a", 40), Title: "Release title",
		Body: "# Release title\n\nComplete notes.", Draft: true, Prerelease: true,
	})
	if err != nil || evidence != (forge.WriteEvidence{Attempted: true, Disposition: forge.WriteAccepted}) {
		t.Fatalf("CreateRelease() evidence = %#v, error = %v", evidence, err)
	}
	if release.Handle == nil || release.Tag != "server tag" || release.Title != "server title" || release.Body != "server body" || !release.Draft || !release.Prerelease {
		t.Fatalf("CreateRelease() release = %#v", release)
	}
}

func TestBackendCreateReleaseMarksInvalidAcknowledgmentUncertain(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		_ = json.NewEncoder(w).Encode(releaseResponse{TagName: "v1.2.3"})
	}))
	defer server.Close()
	backend := NewBackend(testDestination(server.URL), server.Client())

	_, evidence, err := backend.CreateRelease(context.Background(), validCreateReleaseRequest())
	var failure *forge.Failure
	if !errors.As(err, &failure) || failure.Kind != forge.FailureMalformed || evidence != (forge.WriteEvidence{Attempted: true, Disposition: forge.WriteUncertain}) {
		t.Fatalf("CreateRelease() evidence = %#v, error = %v", evidence, err)
	}
}

func TestBackendCreateReleaseClassifiesConflictAndServerFailure(t *testing.T) {
	for _, test := range []struct {
		status      int
		disposition forge.WriteDisposition
	}{
		{status: http.StatusBadRequest, disposition: forge.WriteRejected},
		{status: http.StatusConflict, disposition: forge.WriteConflict},
		{status: http.StatusServiceUnavailable, disposition: forge.WriteUncertain},
	} {
		t.Run(http.StatusText(test.status), func(t *testing.T) {
			server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { w.WriteHeader(test.status) }))
			defer server.Close()
			backend := NewBackend(testDestination(server.URL), server.Client())

			_, evidence, err := backend.CreateRelease(context.Background(), validCreateReleaseRequest())
			if err == nil || evidence != (forge.WriteEvidence{Attempted: true, Disposition: test.disposition}) {
				t.Fatalf("CreateRelease() evidence = %#v, error = %v", evidence, err)
			}
		})
	}
}

func TestBackendUploadAssetBorrowsReaderAndValidatesAcknowledgment(t *testing.T) {
	var uploaded string
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost || r.URL.Path != "/api/v1/repos/owner/project/releases/12/assets" || r.URL.Query().Get("name") != "app.bin" {
			t.Errorf("request = %s %s?%s", r.Method, r.URL.Path, r.URL.RawQuery)
		}
		if got, want := r.Header.Get("Authorization"), "token fixture-secret-token"; got != want {
			t.Errorf("authorization = %q, want %q", got, want)
		}
		file, header, err := r.FormFile("attachment")
		if err != nil {
			t.Errorf("attachment: %v", err)
		} else {
			defer file.Close()
			content, readErr := io.ReadAll(file)
			if readErr != nil {
				t.Errorf("read attachment: %v", readErr)
			}
			if header.Filename != "app.bin" {
				t.Errorf("multipart filename = %q", header.Filename)
			}
			uploaded = string(content)
		}
		_ = json.NewEncoder(w).Encode(assetResponse{ID: 50, Name: "app.bin"})
	}))
	defer server.Close()
	backend := NewBackend(testDestination(server.URL), server.Client())
	reader := &trackedReader{Reader: strings.NewReader("streamed bytes")}

	evidence, err := backend.UploadAsset(context.Background(), releaseHandle{id: 12}, "app.bin", reader)
	if err != nil || evidence != (forge.WriteEvidence{Attempted: true, Disposition: forge.WriteAccepted}) {
		t.Fatalf("UploadAsset() evidence = %#v, error = %v", evidence, err)
	}
	if uploaded != "streamed bytes" || reader.closed {
		t.Fatalf("uploaded = %q, caller reader closed = %v", uploaded, reader.closed)
	}
}

func TestBackendUploadAssetMarksBadAcknowledgmentUncertain(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		_ = json.NewEncoder(w).Encode(assetResponse{ID: 50, Name: "different.bin"})
	}))
	defer server.Close()
	backend := NewBackend(testDestination(server.URL), server.Client())

	evidence, err := backend.UploadAsset(context.Background(), releaseHandle{id: 12}, "app.bin", strings.NewReader("data"))
	var failure *forge.Failure
	if !errors.As(err, &failure) || failure.Kind != forge.FailureMalformed || evidence != (forge.WriteEvidence{Attempted: true, Disposition: forge.WriteUncertain}) {
		t.Fatalf("UploadAsset() evidence = %#v, error = %v", evidence, err)
	}
}

func TestBackendUploadAssetClassifiesKnownRejectionAndConflict(t *testing.T) {
	for _, test := range []struct {
		status      int
		disposition forge.WriteDisposition
	}{
		{status: http.StatusBadRequest, disposition: forge.WriteRejected},
		{status: http.StatusConflict, disposition: forge.WriteConflict},
		{status: http.StatusInternalServerError, disposition: forge.WriteUncertain},
	} {
		t.Run(http.StatusText(test.status), func(t *testing.T) {
			server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { w.WriteHeader(test.status) }))
			defer server.Close()
			backend := NewBackend(testDestination(server.URL), server.Client())

			evidence, err := backend.UploadAsset(context.Background(), releaseHandle{id: 12}, "app.bin", strings.NewReader("data"))
			if err == nil || evidence != (forge.WriteEvidence{Attempted: true, Disposition: test.disposition}) {
				t.Fatalf("UploadAsset() evidence = %#v, error = %v", evidence, err)
			}
		})
	}
}

func TestBackendUploadAssetPreservesCancellationAsUncertain(t *testing.T) {
	server := httptest.NewServer(http.NotFoundHandler())
	defer server.Close()
	ctx, cancel := context.WithCancel(context.Background())
	cancel()

	evidence, err := NewBackend(testDestination(server.URL), server.Client()).UploadAsset(ctx, releaseHandle{id: 12}, "app.bin", strings.NewReader("data"))
	if evidence != (forge.WriteEvidence{Attempted: true, Disposition: forge.WriteUncertain}) || !errors.Is(err, context.Canceled) {
		t.Fatalf("UploadAsset() evidence = %#v, error = %v", evidence, err)
	}
}

func TestBackendUploadAssetWaitsForMultipartWriterAfterReaderFailure(t *testing.T) {
	readerErr := errors.New("asset reader failed")
	readDone := make(chan struct{})
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method == http.MethodGet && r.URL.Path == "/api/v1/repos/owner/project/releases/tags/v1.2.3" {
			_ = json.NewEncoder(w).Encode(releaseResponse{ID: 10, TagName: "v1.2.3"})
			return
		}
		_, _ = io.Copy(io.Discard, r.Body)
		_ = json.NewEncoder(w).Encode(assetResponse{ID: 50, Name: "app.bin", Size: 0})
	}))
	defer server.Close()
	backend := NewBackend(testDestination(server.URL), server.Client())
	release, err := backend.FindRelease(context.Background(), "v1.2.3")
	if err != nil {
		t.Fatalf("FindRelease() error = %v", err)
	}

	evidence, err := backend.UploadAsset(context.Background(), release.Handle, "app.bin", failingUploadReader{err: readerErr, done: readDone})
	select {
	case <-readDone:
	default:
		t.Fatal("UploadAsset() returned before the multipart worker finished reading")
	}
	if !errors.Is(err, readerErr) {
		t.Fatalf("UploadAsset() error = %v, want reader cause %v", err, readerErr)
	}
	if !evidence.Attempted || evidence.Disposition != forge.WriteUncertain {
		t.Fatalf("UploadAsset() evidence = %#v, want uncertain attempted write", evidence)
	}
}

type failingUploadReader struct {
	err  error
	done chan struct{}
}

func (reader failingUploadReader) Read([]byte) (int, error) {
	close(reader.done)
	return 0, reader.err
}

func validCreateReleaseRequest() forge.CreateReleaseRequest {
	return forge.CreateReleaseRequest{Tag: "v1.2.3", Commit: strings.Repeat("a", 40), Title: "Release", Body: "# Release"}
}

func testDestination(baseURL string) Destination {
	return Destination{BaseURL: baseURL, Owner: "owner", Repository: "project", Token: "fixture-secret-token"}
}

type trackedReader struct {
	io.Reader
	closed bool
}

func (reader *trackedReader) Close() error {
	reader.closed = true
	return nil
}