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

import (
	"bytes"
	"context"
	"io"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"testing"

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

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

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)
		})
	}
}

// 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)
	}
}

//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(), 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(),
		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(),
		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(),
		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)
}