//nolint:testpackage // white-box tests exercise unexported internals
package cli

import (
	"bytes"
	"context"
	"flag"
	"fmt"
	"io"
	"maps"
	"net"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"strconv"
	"sync"
	"sync/atomic"
	"testing"
	"time"

	"github.com/spf13/afero"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	urfcli "github.com/urfave/cli/v2"
	"sneak.berlin/go/mfer/mfer"
)

const (
	testFileTxt = "file.txt"
	testDirFile = "dir/file.txt"
	testIndexMF = "https://example.com/path/index.mf"

	// Exactly what url.Parse renders, with no wrapper of our own.
	urlParseControlCharErr = `parse "http://example.com/\x7f": ` +
		`net/url: invalid control character in URL`
)

func TestEncodeFilePath(t *testing.T) {
	t.Parallel()

	tests := []struct {
		input    string
		expected string
	}{
		{testFileTxt, testFileTxt},
		{testDirFile, testDirFile},
		{"my file.txt", "my%20file.txt"},
		{"dir/my file.txt", "dir/my%20file.txt"},
		{"file#1.txt", "file%231.txt"},
		{"file?v=1.txt", "file%3Fv=1.txt"},
		{"path/to/file with spaces.txt", "path/to/file%20with%20spaces.txt"},
		{"100%done.txt", "100%25done.txt"},
	}

	for _, tt := range tests {
		t.Run(tt.input, func(t *testing.T) {
			t.Parallel()

			result := encodeFilePath(tt.input)
			assert.Equal(t, tt.expected, result)
		})
	}
}

func TestSanitizePath(t *testing.T) {
	t.Parallel()

	// Valid paths that should be accepted
	validTests := []struct {
		input    string
		expected string
	}{
		{testFileTxt, testFileTxt},
		{testDirFile, testDirFile},
		{"dir/subdir/file.txt", "dir/subdir/file.txt"},
		{"./file.txt", testFileTxt},
		{"./dir/file.txt", testDirFile},
		{"dir/./file.txt", testDirFile},
	}

	for _, tt := range validTests {
		t.Run("valid:"+tt.input, func(t *testing.T) {
			t.Parallel()

			result, err := sanitizePath(tt.input)
			require.NoError(t, err)
			assert.Equal(t, tt.expected, result)
		})
	}

	// Invalid paths that should be rejected
	invalidTests := []struct {
		input string
		desc  string
	}{
		{"", "empty path"},
		{"..", "parent directory"},
		{"../file.txt", "parent traversal"},
		{"../../file.txt", "double parent traversal"},
		{"dir/../../../file.txt", "traversal escaping base"},
		{"/etc/passwd", "absolute path"},
		{"/file.txt", "absolute path with single component"},
		{"dir/../../etc/passwd", "traversal to system file"},
	}

	for _, tt := range invalidTests {
		t.Run("invalid:"+tt.desc, func(t *testing.T) {
			t.Parallel()

			_, err := sanitizePath(tt.input)
			assert.Error(t, err, "expected error for path: %s", tt.input)
		})
	}
}

func TestResolveManifestURL(t *testing.T) {
	t.Parallel()

	tests := []struct {
		input    string
		expected string
	}{
		// Already ends with .mf - use as-is
		{testIndexMF, testIndexMF},
		{"https://example.com/path/custom.mf", "https://example.com/path/custom.mf"},
		{"https://example.com/foo.mf", "https://example.com/foo.mf"},

		// Directory with trailing slash - append index.mf
		{"https://example.com/path/", testIndexMF},
		{"https://example.com/", "https://example.com/index.mf"},

		// Directory without trailing slash - add slash and index.mf
		{"https://example.com/path", testIndexMF},
		{"https://example.com", "https://example.com/index.mf"},

		// With query strings
		{
			"https://example.com/path?foo=bar",
			"https://example.com/path/index.mf?foo=bar",
		},
	}

	for _, tt := range tests {
		t.Run(tt.input, func(t *testing.T) {
			t.Parallel()

			result, err := resolveManifestURL(tt.input)
			require.NoError(t, err)
			assert.Equal(t, tt.expected, result)
		})
	}

	// The sole caller wraps this error as "invalid URL: %w", so
	// resolveManifestURL must return url.Parse's error unadorned.
	t.Run("invalid:control character", func(t *testing.T) {
		t.Parallel()

		_, err := resolveManifestURL("http://example.com/\x7f")
		require.ErrorContains(t, err, urlParseControlCharErr)
		assert.NotContains(t, err.Error(), "failed to parse URL")
	})
}

// scanToManifest scans sourceFs and returns the serialized manifest bytes.
func scanToManifest(t *testing.T, sourceFs afero.Fs) []byte {
	t.Helper()

	s := mfer.NewScannerWithOptions(&mfer.ScannerOptions{Fs: sourceFs})
	require.NoError(t, s.EnumerateFS(sourceFs, "/", nil))

	var manifestBuf bytes.Buffer

	require.NoError(t, s.ToManifest(context.Background(), &manifestBuf, nil))

	return manifestBuf.Bytes()
}

// chdirTemp switches the working directory to a fresh temp dir for the
// duration of the test and returns its path.
func chdirTemp(t *testing.T) string {
	t.Helper()

	destDir := t.TempDir()

	origDir, err := os.Getwd()
	require.NoError(t, err)

	require.NoError(t, os.Chdir(destDir))
	t.Cleanup(func() { _ = os.Chdir(origDir) })

	return destDir
}

// fetchTestHandler serves the manifest at /index.mf and the given files
// at their paths.
func fetchTestHandler(
	manifestData []byte, testFiles map[string][]byte,
) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		path := r.URL.Path
		if path == "/index.mf" {
			w.Header().Set("Content-Type", "application/octet-stream")
			_, _ = w.Write(manifestData)

			return
		}

		// Strip leading slash
		if len(path) > 0 && path[0] == '/' {
			path = path[1:]
		}

		content, exists := testFiles[path]
		if !exists {
			http.NotFound(w, r)

			return
		}

		w.Header().Set("Content-Type", "application/octet-stream")
		_, _ = w.Write(content)
	}
}

// manifestOf scans a tree holding files and returns its manifest bytes.
func manifestOf(t *testing.T, files map[string][]byte) []byte {
	t.Helper()

	sourceFs := afero.NewMemMapFs()
	for p, content := range files {
		require.NoError(t, sourceFs.MkdirAll(filepath.Dir("/"+p), 0o755))
		require.NoError(t, afero.WriteFile(sourceFs, "/"+p, content, 0o644))
	}

	return scanToManifest(t, sourceFs)
}

// filesUnder returns the content of every file under dir, by its path
// relative to dir.
func filesUnder(t *testing.T, dir string) map[string][]byte {
	t.Helper()

	files := map[string][]byte{}

	err := filepath.WalkDir(dir, func(path string, entry os.DirEntry, err error) error {
		if err != nil || entry.IsDir() {
			return err
		}

		rel, err := filepath.Rel(dir, path)
		if err != nil {
			return err
		}

		content, err := os.ReadFile(path) //nolint:gosec // test-controlled path
		files[filepath.ToSlash(rel)] = content

		return err
	})
	require.NoError(t, err)

	return files
}

// testClient returns the client tests download with. Its retries wait
// milliseconds rather than seconds.
func testClient() retryingClient {
	return retryingClient{
		client:     &http.Client{Timeout: 10 * time.Second},
		firstDelay: time.Millisecond,
	}
}

// getNothing calls client.get for rawURL with a use that reads nothing,
// under a context that expires after timeout. It holds runMu, since get
// logs each retry to the process-global logger, and starts the timeout
// only once it has the lock.
func getNothing(client retryingClient, rawURL string, timeout time.Duration) error {
	return runLocked(func() error {
		ctx, cancel := context.WithTimeout(context.Background(), timeout)
		defer cancel()

		return client.get(ctx, rawURL, func(*http.Response) error { return nil })
	})
}

//nolint:paralleltest // changes the process-global working directory
func TestFetchFromHTTP(t *testing.T) {
	// Create source filesystem with test files
	sourceFs := afero.NewMemMapFs()

	testFiles := map[string][]byte{
		"file1.txt":         []byte("Hello, World!"),
		"file2.txt":         []byte("This is file 2 with more content."),
		"subdir/file3.txt":  []byte("Nested file content here."),
		"subdir/deep/f.txt": []byte("Deeply nested file."),
	}

	for path, content := range testFiles {
		fullPath := "/" + path // MemMapFs needs absolute paths
		dir := filepath.Dir(fullPath)
		require.NoError(t, sourceFs.MkdirAll(dir, 0o755))
		require.NoError(t, afero.WriteFile(sourceFs, fullPath, content, 0o644))
	}

	// Generate manifest using scanner
	manifestData := scanToManifest(t, sourceFs)

	// Create HTTP server that serves the source filesystem
	server := httptest.NewServer(fetchTestHandler(manifestData, testFiles))
	defer server.Close()

	// Change to a fresh destination directory for the test
	destDir := chdirTemp(t)

	// Parse the manifest to get file entries
	manifest, err := mfer.NewManifestFromReader(bytes.NewReader(manifestData))
	require.NoError(t, err)

	files := manifest.Files()
	require.Len(t, files, len(testFiles))

	// Download each file using downloadFile
	progress := make(chan DownloadProgress, 10)

	go func() {
		for p := range progress {
			_ = p // drain progress channel
		}
	}()

	baseURL := server.URL + "/"

	for _, f := range files {
		localPath, err := sanitizePath(f.GetPath())
		require.NoError(t, err)

		fileURL := baseURL + f.GetPath()
		err = downloadFile(context.Background(), testClient(),
			fileURL, ".", localPath, f, progress)
		require.NoError(t, err, "failed to download %s", f.GetPath())
	}

	close(progress)

	// Verify downloaded files match originals
	for path, expectedContent := range testFiles {
		downloadedPath := filepath.Join(destDir, path)
		//nolint:gosec // test-controlled path
		downloadedContent, err := os.ReadFile(downloadedPath)
		require.NoError(t, err, "failed to read downloaded file %s", path)
		assert.Equal(t, expectedContent, downloadedContent,
			"content mismatch for %s", path)
	}
}

//nolint:paralleltest // changes the process-global working directory
func TestFetchHashMismatch(t *testing.T) {
	// Create source filesystem with a test file
	sourceFs := afero.NewMemMapFs()
	originalContent := []byte("Original content")
	require.NoError(t, afero.WriteFile(sourceFs, "/file.txt", originalContent, 0o644))

	// Generate and parse manifest
	manifestData := scanToManifest(t, sourceFs)

	manifest, err := mfer.NewManifestFromReader(bytes.NewReader(manifestData))
	require.NoError(t, err)

	files := manifest.Files()
	require.Len(t, files, 1)

	// Create server that serves DIFFERENT content (to trigger hash mismatch)
	tamperedContent := []byte("Tampered content!")

	server := httptest.NewServer(
		http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
			w.Header().Set("Content-Type", "application/octet-stream")
			_, _ = w.Write(tamperedContent)
		}))
	defer server.Close()

	// Work in a fresh temp directory
	chdirTemp(t)

	// Try to download - should fail with hash mismatch
	err = downloadFile(context.Background(), testClient(),
		server.URL+"/file.txt", ".", testFileTxt, files[0], nil)
	require.Error(t, err)
	assert.Contains(t, err.Error(), "mismatch")

	// Verify temp file was cleaned up
	_, err = os.Stat(".file.txt.tmp")
	assert.True(t, os.IsNotExist(err),
		"temp file should be cleaned up on hash mismatch")

	// Verify final file was not created
	_, err = os.Stat(testFileTxt)
	assert.True(t, os.IsNotExist(err),
		"final file should not exist on hash mismatch")
}

//nolint:paralleltest // changes the process-global working directory
func TestFetchSizeMismatch(t *testing.T) {
	// Create source filesystem with a test file
	sourceFs := afero.NewMemMapFs()
	originalContent := []byte("Original content with specific size")
	require.NoError(t, afero.WriteFile(sourceFs, "/file.txt", originalContent, 0o644))

	// Generate and parse manifest
	manifestData := scanToManifest(t, sourceFs)

	manifest, err := mfer.NewManifestFromReader(bytes.NewReader(manifestData))
	require.NoError(t, err)

	files := manifest.Files()
	require.Len(t, files, 1)

	// Create server that serves content with wrong size
	wrongSizeContent := []byte("Short")

	server := httptest.NewServer(
		http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
			w.Header().Set("Content-Type", "application/octet-stream")
			_, _ = w.Write(wrongSizeContent)
		}))
	defer server.Close()

	// Work in a fresh temp directory
	chdirTemp(t)

	// Try to download - should fail with size mismatch
	err = downloadFile(context.Background(), testClient(),
		server.URL+"/file.txt", ".", testFileTxt, files[0], nil)
	require.Error(t, err)
	assert.Contains(t, err.Error(), "size mismatch")

	// Verify temp file was cleaned up
	_, err = os.Stat(".file.txt.tmp")
	assert.True(t, os.IsNotExist(err),
		"temp file should be cleaned up on size mismatch")
}

//nolint:paralleltest // changes the process-global working directory
func TestFetchProgress(t *testing.T) {
	// Create source filesystem with a larger test file
	sourceFs := afero.NewMemMapFs()
	// Create content large enough to trigger multiple progress updates
	content := bytes.Repeat([]byte("x"), 100*1024) // 100KB
	require.NoError(t, afero.WriteFile(sourceFs, "/large.txt", content, 0o644))

	// Generate and parse manifest
	manifestData := scanToManifest(t, sourceFs)

	manifest, err := mfer.NewManifestFromReader(bytes.NewReader(manifestData))
	require.NoError(t, err)

	files := manifest.Files()
	require.Len(t, files, 1)

	// Create server that serves the content
	server := httptest.NewServer(
		http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
			w.Header().Set("Content-Type", "application/octet-stream")
			w.Header().Set("Content-Length", "102400")
			// Write in chunks to allow progress reporting
			reader := bytes.NewReader(content)
			_, _ = io.Copy(w, reader)
		}))
	defer server.Close()

	// Work in a fresh temp directory
	chdirTemp(t)

	// Set up progress channel and collect updates
	progress := make(chan DownloadProgress, 100)

	var progressUpdates []DownloadProgress

	done := make(chan struct{})

	go func() {
		for p := range progress {
			progressUpdates = append(progressUpdates, p)
		}

		close(done)
	}()

	// Download
	err = downloadFile(context.Background(), testClient(),
		server.URL+"/large.txt", ".", "large.txt", files[0], progress)
	close(progress)
	<-done

	require.NoError(t, err)

	// Verify we got progress updates
	assert.NotEmpty(t, progressUpdates, "should have received progress updates")

	// Verify final progress shows complete
	if len(progressUpdates) > 0 {
		last := progressUpdates[len(progressUpdates)-1]
		assert.Equal(t, int64(len(content)), last.BytesRead,
			"final progress should show all bytes read")
		assert.Equal(t, "large.txt", last.Path)
	}

	// Verify file was downloaded correctly
	downloaded, err := os.ReadFile("large.txt")
	require.NoError(t, err)
	assert.Equal(t, content, downloaded)
}

// TestFetchRefusesSymlinks runs fetch into a destination directory that
// holds a symlink pointing outside it, in each of the three places fetch
// writes: a parent directory, the temp file, and the file itself, which
// the temp file is renamed onto; and once as a directory inside a plain
// directory. The fetch must fail and nothing outside may change.
//
//nolint:paralleltest // changes the process-global working directory
func TestFetchRefusesSymlinks(t *testing.T) {
	tests := []struct {
		name   string
		entry  string // the manifest's only file
		link   string // symlink placed in the destination directory
		target string // what link points to, relative to the outside directory
	}{
		{"parent directory", "sub/deeper/file.txt", "sub", "."},
		{"directory inside a plain directory", "docs/data/passwd", "docs/data", "."},
		{"temp file", testFileTxt, ".file.txt.tmp", "new.txt"},
		{"file", testFileTxt, testFileTxt, "new.txt"},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			content := []byte("fetched")
			sourceFs := afero.NewMemMapFs()
			require.NoError(t, sourceFs.MkdirAll(filepath.Dir("/"+tt.entry), 0o755))
			require.NoError(t, afero.WriteFile(sourceFs, "/"+tt.entry, content, 0o644))

			server := httptest.NewServer(fetchTestHandler(
				scanToManifest(t, sourceFs), map[string][]byte{tt.entry: content}))
			defer server.Close()

			outside := t.TempDir()

			chdirTemp(t)
			require.NoError(t, os.MkdirAll(filepath.Dir(tt.link), 0o750))
			require.NoError(t, os.Symlink(filepath.Join(outside, tt.target), tt.link))

			opts := testOpts([]string{testApp, cmdFetch, "-q", server.URL}, afero.NewOsFs())
			assert.Equal(t, 1, runCLI(opts))
			assert.Contains(t, testStderr(t, opts), "failed to download "+tt.entry+
				": symlink in path not allowed: "+tt.link)

			written, err := os.ReadDir(outside)
			require.NoError(t, err)
			assert.Empty(t, written, "fetch wrote outside the destination")
		})
	}
}

// TestFetchReplacesHardLinkAtTempName runs fetch into a destination
// directory that holds, at the temp file's name, a hard link to a file
// outside it. To fetch that is an ordinary leftover from an interrupted
// earlier run: it must replace it and succeed, and the outside file must
// not change.
//
//nolint:paralleltest // changes the process-global working directory
func TestFetchReplacesHardLinkAtTempName(t *testing.T) {
	content := []byte("fetched")
	sourceFs := afero.NewMemMapFs()
	require.NoError(t, afero.WriteFile(sourceFs, "/"+testFileTxt, content, 0o644))

	server := httptest.NewServer(fetchTestHandler(
		scanToManifest(t, sourceFs), map[string][]byte{testFileTxt: content}))
	defer server.Close()

	outsideFile := filepath.Join(t.TempDir(), "secret.txt")
	require.NoError(t, os.WriteFile(outsideFile, []byte("outside"), 0o600))

	chdirTemp(t)
	require.NoError(t, os.Link(outsideFile, ".file.txt.tmp"))

	opts := testOpts([]string{testApp, cmdFetch, "-q", server.URL}, afero.NewOsFs())
	require.Equal(t, 0, runCLI(opts), testStderr(t, opts))

	fetched, err := os.ReadFile(testFileTxt)
	require.NoError(t, err)
	assert.Equal(t, content, fetched)

	outside, err := os.ReadFile(outsideFile) //nolint:gosec // test-controlled path
	require.NoError(t, err)
	assert.Equal(t, "outside", string(outside), "fetch wrote outside the destination")
}

// TestGetRetriesTransientStatusesOnly answers every request with one
// status and counts the requests: a 5xx or 429 is retried until
// fetchAttempts runs out, and any other status fails at once.
func TestGetRetriesTransientStatusesOnly(t *testing.T) {
	t.Parallel()

	tests := []struct {
		status   int
		requests int32
	}{
		{http.StatusNotFound, 1},
		{http.StatusForbidden, 1},
		{http.StatusInternalServerError, fetchAttempts},
		{http.StatusServiceUnavailable, fetchAttempts},
		{http.StatusTooManyRequests, fetchAttempts},
	}

	for _, tt := range tests {
		t.Run(http.StatusText(tt.status), func(t *testing.T) {
			t.Parallel()

			var requests atomic.Int32

			server := httptest.NewServer(
				http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
					requests.Add(1)
					w.WriteHeader(tt.status)
				}))
			defer server.Close()

			err := getNothing(testClient(), server.URL, 10*time.Second)
			require.ErrorIs(t, err, errHTTPStatus)
			require.EqualError(t, err, fmt.Sprintf("HTTP %d", tt.status))
			assert.Equal(t, tt.requests, requests.Load())
		})
	}
}

// TestGetTimesOutOnStalledServer points get at a server that takes a
// request and never answers it. The try must give up at the client's
// timeout and be retried; when every try stalls, get must return a
// timeout error rather than hang.
func TestGetTimesOutOnStalledServer(t *testing.T) {
	t.Parallel()

	tests := []struct {
		name       string
		stallEvery bool
	}{
		{"first request stalls", false},
		{"every request stalls", true},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			t.Parallel()

			var requests atomic.Int32

			stop := make(chan struct{})
			server := httptest.NewServer(
				http.HandlerFunc(func(_ http.ResponseWriter, r *http.Request) {
					if requests.Add(1) == 1 || tt.stallEvery {
						select {
						case <-r.Context().Done():
						case <-stop:
						}
					}
				}))

			defer server.Close()
			defer close(stop)

			client := testClient()
			client.client.Timeout = 50 * time.Millisecond

			err := getNothing(client, server.URL, 10*time.Second)
			if !tt.stallEvery {
				require.NoError(t, err)

				return
			}

			var netErr net.Error
			require.ErrorAs(t, err, &netErr)
			assert.True(t, netErr.Timeout(), "want a timeout, got %v", err)
		})
	}
}

// TestGetHonorsRetryAfter answers the first request with a 503 and a
// Retry-After header, and any later one with 200 OK. The client's own
// wait before a retry is an hour, so get finishes in time only if it
// waits as long as Retry-After says instead. A Retry-After longer than
// maxRetryAfter must fail at once.
func TestGetHonorsRetryAfter(t *testing.T) {
	t.Parallel()

	tests := []struct {
		name     string
		value    string
		requests int32
		wantErr  bool
	}{
		{"seconds", "0", 2, false},
		{"HTTP date", time.Now().Add(-time.Minute).UTC().Format(http.TimeFormat), 2, false},
		{"too long", strconv.Itoa(int((maxRetryAfter + time.Second).Seconds())), 1, true},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			t.Parallel()

			var requests atomic.Int32

			server := httptest.NewServer(
				http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
					if requests.Add(1) == 1 {
						w.Header().Set("Retry-After", tt.value)
						w.WriteHeader(http.StatusServiceUnavailable)
					}
				}))
			defer server.Close()

			client := testClient()
			client.firstDelay = time.Hour

			err := getNothing(client, server.URL, 10*time.Second)
			if tt.wantErr {
				require.ErrorIs(t, err, errHTTPStatus)
			} else {
				require.NoError(t, err)
			}

			assert.Equal(t, tt.requests, requests.Load())
		})
	}
}

// TestGetStopsWaitingWhenCanceled gives get a server that always answers
// 503 and an hour's wait before each retry, then lets the context expire
// during that wait. get returning at all shows it stopped waiting.
func TestGetStopsWaitingWhenCanceled(t *testing.T) {
	t.Parallel()

	server := httptest.NewServer(
		http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
			w.WriteHeader(http.StatusServiceUnavailable)
		}))
	defer server.Close()

	client := testClient()
	client.firstDelay = time.Hour

	err := getNothing(client, server.URL, 50*time.Millisecond)
	require.ErrorIs(t, err, context.DeadlineExceeded)
}

// TestDownloadFileRetriesToSuccess serves a file that fails twice before
// it succeeds: first with a 503, then with a body cut off halfway. The
// download must end with the whole, verified file and no temp file.
//
//nolint:paralleltest // changes the process-global working directory
func TestDownloadFileRetriesToSuccess(t *testing.T) {
	content := []byte("the whole file, every byte of it")

	manifest, err := mfer.NewManifestFromReader(bytes.NewReader(
		manifestOf(t, map[string][]byte{testFileTxt: content})))
	require.NoError(t, err)

	var requests atomic.Int32

	server := httptest.NewServer(
		http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
			switch requests.Add(1) {
			case 1:
				w.WriteHeader(http.StatusServiceUnavailable)
			case 2:
				// Promise the whole file but send half of it; the server
				// then closes the connection.
				w.Header().Set("Content-Length", strconv.Itoa(len(content)))
				_, _ = w.Write(content[:len(content)/2])
			default:
				_, _ = w.Write(content)
			}
		}))
	defer server.Close()

	chdirTemp(t)

	err = downloadFile(context.Background(), testClient(),
		server.URL+"/"+testFileTxt, ".", testFileTxt, manifest.Files()[0], nil)
	require.NoError(t, err)
	assert.Equal(t, int32(3), requests.Load())

	fetched, err := os.ReadFile(testFileTxt)
	require.NoError(t, err)
	assert.Equal(t, content, fetched)

	_, err = os.Stat(".file.txt.tmp")
	assert.True(t, os.IsNotExist(err), "temp file left behind")
}

// TestFetchBaseURLForms fetches one tree by its directory URL with and
// without a trailing slash, with a query string, and by its manifest URL.
// Each must request the same manifest and file paths.
//
//nolint:paralleltest // changes the process-global working directory
func TestFetchBaseURLForms(t *testing.T) {
	files := map[string][]byte{"one.txt": []byte("1"), "sub/two.txt": []byte("2")}
	tree := http.StripPrefix("/tree", fetchTestHandler(manifestOf(t, files), files))

	var (
		mu        sync.Mutex
		requested []string
	)

	server := httptest.NewServer(
		http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			mu.Lock()

			requested = append(requested, r.URL.Path)

			mu.Unlock()

			tree.ServeHTTP(w, r)
		}))
	defer server.Close()

	inputs := []string{"/tree", "/tree/", "/tree?key=value", "/tree/index.mf"}
	for _, input := range inputs {
		t.Run(input, func(t *testing.T) {
			mu.Lock()
			requested = nil
			mu.Unlock()

			chdirTemp(t)

			opts := testOpts([]string{testApp, cmdFetch, "-q", server.URL + input},
				afero.NewOsFs())
			require.Equal(t, 0, runCLI(opts), testStderr(t, opts))

			mu.Lock()
			defer mu.Unlock()

			assert.ElementsMatch(t,
				[]string{"/tree/index.mf", "/tree/one.txt", "/tree/sub/two.txt"}, requested)
		})
	}
}

// TestFetchEscapedPaths fetches files whose names need escaping in a URL,
// one of them a name that is itself an escape sequence. Each must arrive
// under its own name with its own content.
//
//nolint:paralleltest // changes the process-global working directory
func TestFetchEscapedPaths(t *testing.T) {
	files := map[string][]byte{
		"a b.txt":                []byte("space"),
		"a%20b.txt":              []byte("percent sign, two, zero"),
		"100%.txt":               []byte("percent sign"),
		"q?x=1#frag.txt":         []byte("question mark and hash"),
		"dir with space/sub.txt": []byte("directory with a space"),
	}

	server := httptest.NewServer(fetchTestHandler(manifestOf(t, files), files))
	defer server.Close()

	chdirTemp(t)

	opts := testOpts([]string{testApp, cmdFetch, "-q", server.URL}, afero.NewOsFs())
	require.Equal(t, 0, runCLI(opts), testStderr(t, opts))

	for name, content := range files {
		fetched, err := os.ReadFile(name) //nolint:gosec // test-controlled path
		require.NoError(t, err)
		assert.Equal(t, content, fetched, name)
	}
}

// TestFetchTree runs fetch on a tree with nested directories. Every file
// the manifest lists must land under its own path with its own content,
// beside the manifest, and nothing else may be left in the destination.
//
//nolint:paralleltest // changes the process-global working directory
func TestFetchTree(t *testing.T) {
	files := map[string][]byte{
		"top.txt":            []byte("at the top"),
		"sub/one.txt":        []byte("one level down"),
		"sub/deeper/two.txt": []byte("two levels down"),
		"other/deep/est.txt": []byte("in a second directory"),
	}

	manifest := manifestOf(t, files)

	server := httptest.NewServer(fetchTestHandler(manifest, files))
	defer server.Close()

	dest := chdirTemp(t)

	opts := testOpts([]string{testApp, cmdFetch, "-q", server.URL}, afero.NewOsFs())
	require.Equal(t, 0, runCLI(opts), testStderr(t, opts))

	want := maps.Clone(files)
	want[defaultManifestName] = manifest
	assert.Equal(t, want, filesUnder(t, dest))
}

// TestFetchFailsOnHashMismatch runs fetch against a server that serves a
// file with the size the manifest lists but different content. fetch must
// exit non-zero and leave no file in the destination.
//
//nolint:paralleltest // changes the process-global working directory
func TestFetchFailsOnHashMismatch(t *testing.T) {
	listed := map[string][]byte{testDirFile: []byte("original")}
	served := map[string][]byte{testDirFile: []byte("tampered")}

	server := httptest.NewServer(fetchTestHandler(manifestOf(t, listed), served))
	defer server.Close()

	dest := chdirTemp(t)

	opts := testOpts([]string{testApp, cmdFetch, "-q", server.URL}, afero.NewOsFs())
	assert.Equal(t, 1, runCLI(opts))
	assert.Empty(t, filesUnder(t, dest))
}

// TestFetchIntoPartlyFilledDestination runs fetch where an interrupted
// fetch of an older version of the tree left one file current, one file
// out of date and one half written to its temp file, beside a file the
// manifest does not list. fetch skips the current file and downloads the
// other two. The out-of-date file has the same size as the new version,
// so only its hash shows that it must be replaced. The file the manifest
// does not list is left alone, and the manifest is saved beside the files.
//
//nolint:paralleltest // changes the process-global working directory
func TestFetchIntoPartlyFilledDestination(t *testing.T) {
	files := map[string][]byte{
		"current.txt":     []byte("already fetched"),
		"sub/changed.txt": []byte("new version"),
		"sub/partial.txt": []byte("cut off partway"),
	}
	unlisted := []byte("not in the manifest")

	manifest := manifestOf(t, files)
	tree := fetchTestHandler(manifest, files)

	var (
		mu        sync.Mutex
		requested []string
	)

	server := httptest.NewServer(
		http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			mu.Lock()

			requested = append(requested, r.URL.Path)

			mu.Unlock()

			tree.ServeHTTP(w, r)
		}))
	defer server.Close()

	dest := chdirTemp(t)

	require.NoError(t, os.MkdirAll("sub", 0o750))
	require.NoError(t, os.WriteFile("current.txt", files["current.txt"], 0o600))
	require.NoError(t, os.WriteFile("sub/changed.txt", []byte("old version"), 0o600))
	require.NoError(t,
		os.WriteFile(tempPathFor("sub/partial.txt"), []byte("cut off"), 0o600))
	require.NoError(t, os.WriteFile("unlisted.txt", unlisted, 0o600))

	opts := testOpts([]string{testApp, cmdFetch, server.URL}, afero.NewOsFs())
	require.Equal(t, 0, runCLI(opts), testStderr(t, opts))
	assert.Contains(t, testStderr(t, opts), "skipping current.txt: already present")

	want := maps.Clone(files)
	want["unlisted.txt"] = unlisted
	want[defaultManifestName] = manifest
	assert.Equal(t, want, filesUnder(t, dest))

	mu.Lock()
	defer mu.Unlock()

	assert.ElementsMatch(t, []string{
		"/" + defaultManifestName, "/sub/changed.txt", "/sub/partial.txt",
	}, requested)
}

// TestFetchIntoDest fetches a tree with --dest into a directory that does
// not exist yet. The files and the manifest must land there and nowhere
// else, and check must pass on the result with no extra files. A second
// fetch into the same directory must download nothing but the manifest.
//
//nolint:paralleltest // changes the process-global working directory
func TestFetchIntoDest(t *testing.T) {
	files := map[string][]byte{
		"top.txt":     []byte("at the top"),
		"sub/one.txt": []byte("one level down"),
	}

	manifest := manifestOf(t, files)
	tree := fetchTestHandler(manifest, files)

	var (
		mu        sync.Mutex
		requested []string
	)

	server := httptest.NewServer(
		http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			mu.Lock()

			requested = append(requested, r.URL.Path)

			mu.Unlock()

			tree.ServeHTTP(w, r)
		}))
	defer server.Close()

	cwd := chdirTemp(t)
	dest := filepath.Join(t.TempDir(), "mirror")
	fetch := []string{testApp, cmdFetch, "-q", "--" + flagDest, dest, server.URL}

	opts := testOpts(fetch, afero.NewOsFs())
	require.Equal(t, 0, runCLI(opts), testStderr(t, opts))

	want := maps.Clone(files)
	want[defaultManifestName] = manifest
	assert.Equal(t, want, filesUnder(t, dest))
	assert.Empty(t, filesUnder(t, cwd), "fetch wrote outside --dest")

	check := testOpts([]string{
		testApp, cmdCheck, "-q", testFlagBase, dest, testFlagNoExtra,
		filepath.Join(dest, defaultManifestName),
	}, afero.NewOsFs())
	require.Equal(t, 0, runCLI(check), testStderr(t, check))

	mu.Lock()
	requested = nil
	mu.Unlock()

	opts = testOpts(fetch, afero.NewOsFs())
	require.Equal(t, 0, runCLI(opts), testStderr(t, opts))
	assert.Equal(t, want, filesUnder(t, dest))

	mu.Lock()
	defer mu.Unlock()

	assert.Equal(t, []string{"/" + defaultManifestName}, requested)
}

// TestFetchRequireSignature runs fetch with --require-signature. A
// manifest that is unsigned, or signed by another key, must stop fetch
// with check's message before it downloads or writes anything; the
// required key lets it through. The signed cases need gpg and are skipped
// without it, as the other signing tests are.
//
//nolint:paralleltest // signedManifest calls t.Setenv, which bars t.Parallel
func TestFetchRequireSignature(t *testing.T) {
	files := map[string][]byte{testFileTxt: []byte("signed file")}

	t.Run("unsigned", func(t *testing.T) {
		assertFetchRefused(t, manifestOf(t, files), files, msgFpA,
			"manifest is not signed, but signature from "+msgFpA+" is required")
	})

	t.Run("signed", func(t *testing.T) {
		manifest := signedManifest(t, files)

		signer, err := signedChecker(t, manifest).
			ExtractEmbeddedSigningKeyFP(context.Background())
		require.NoError(t, err)

		assertFetchRefused(t, manifest, files, msgFpB,
			"embedded signing key fingerprint "+signer+" does not match required "+msgFpB)

		server := httptest.NewServer(fetchTestHandler(manifest, files))
		defer server.Close()

		dest := t.TempDir()

		opts := testOpts([]string{
			testApp, cmdFetch, "-q", "--" + flagDest, dest,
			"--" + flagRequireSignature, signer, server.URL,
		}, afero.NewOsFs())
		require.Equal(t, 0, runCLI(opts), testStderr(t, opts))
		assert.Equal(t, files[testFileTxt], filesUnder(t, dest)[testFileTxt])
	})
}

// assertFetchRefused serves manifest, a manifest of files, and fetches it
// with --require-signature signer into a directory that does not exist
// yet. fetch must fail with message after requesting only the manifest,
// and must not create the directory.
func assertFetchRefused(
	t *testing.T, manifest []byte, files map[string][]byte, signer, message string,
) {
	t.Helper()

	tree := fetchTestHandler(manifest, files)

	var (
		mu        sync.Mutex
		requested []string
	)

	server := httptest.NewServer(
		http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			mu.Lock()

			requested = append(requested, r.URL.Path)

			mu.Unlock()

			tree.ServeHTTP(w, r)
		}))
	defer server.Close()

	dest := filepath.Join(t.TempDir(), "mirror")

	opts := testOpts([]string{
		testApp, cmdFetch, "-q", "--" + flagDest, dest,
		"--" + flagRequireSignature, signer, server.URL,
	}, afero.NewOsFs())
	assert.Equal(t, 1, runCLI(opts))
	assert.Contains(t, testStderr(t, opts), message)
	assert.NoDirExists(t, dest, "fetch wrote before checking the signer")

	mu.Lock()
	defer mu.Unlock()

	assert.Equal(t, []string{"/" + defaultManifestName}, requested)
}

// TestFetchTimeoutFlag runs fetch with --timeout against a server that
// never answers. Without the flag's limit the request would wait forever;
// once fetch gives up on it, the server cancels fetch's context so that
// fetch returns instead of retrying.
func TestFetchTimeoutFlag(t *testing.T) {
	t.Parallel()

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	server := httptest.NewServer(
		http.HandlerFunc(func(_ http.ResponseWriter, r *http.Request) {
			<-r.Context().Done() // fetch gave up on this request
			cancel()
		}))
	defer server.Close()

	mfa := &CLIApp{Fs: afero.NewMemMapFs()}

	set := flag.NewFlagSet(cmdFetch, flag.ContinueOnError)
	for _, f := range mfa.fetchCommand().Flags {
		require.NoError(t, f.Apply(set))
	}

	require.NoError(t, set.Parse([]string{"--" + flagTimeout, "100ms", server.URL}))

	cliCtx := urfcli.NewContext(nil, set, nil)
	cliCtx.Context = ctx

	// fetchManifestOperation logs to the process-global logger.
	err := runLocked(func() error { return mfa.fetchManifestOperation(cliCtx) })
	require.Error(t, err)
}

// TestFetchRejectsTimeoutOfZeroOrLess runs fetch with a --timeout of zero
// and of less than zero. http.Client takes either as no time limit at all,
// so fetch must refuse it before making any request.
func TestFetchRejectsTimeoutOfZeroOrLess(t *testing.T) {
	t.Parallel()

	var requests atomic.Int32

	server := httptest.NewServer(
		http.HandlerFunc(func(http.ResponseWriter, *http.Request) {
			requests.Add(1)
		}))
	defer server.Close()

	for _, timeout := range []string{"0", "-1s"} {
		opts := testOpts(
			[]string{testApp, cmdFetch, "--" + flagTimeout + "=" + timeout, server.URL},
			afero.NewMemMapFs())

		assert.Equal(t, 1, runCLI(opts), timeout)
		assert.Contains(t, testStderr(t, opts), errInvalidTimeout.Error(), timeout)
	}

	assert.Zero(t, requests.Load(), "fetch made a request")
}