// Copyright 2015 Light Code Labs, LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package staticfiles

import (
	"context"
	"errors"
	"io/ioutil"
	"log"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"testing"
	"time"

	"github.com/caddyserver/caddy"
)

// TestServeHTTP covers positive scenarios when serving files.
func TestServeHTTP(t *testing.T) {
	tmpWebRootDir := beforeServeHTTPTest(t)
	defer afterServeHTTPTest(t, tmpWebRootDir)

	fileServer := FileServer{
		Root:       http.Dir(filepath.Join(tmpWebRootDir, webrootName)),
		Hide:       []string{"dir/hidden.html"},
		IndexPages: DefaultIndexPages,
	}

	movedPermanently := "Moved Permanently"

	tests := []struct {
		url                   string
		stripPathPrefix       string // for when sites are defined with a path (e.g. "example.com/foo/")
		acceptEncoding        string
		expectedLocation      string
		expectedStatus        int
		expectedBodyContent   string
		expectedEtag          string
		expectedVary          string
		expectedEncoding      string
		expectedContentLength string
	}{
		// Test 0 - access without any path
		{
			url:            "https://foo",
			expectedStatus: http.StatusNotFound,
		},
		// Test 1 - access root (without index.html)
		{
			url:            "https://foo/",
			expectedStatus: http.StatusNotFound,
		},
		// Test 2 - access existing file
		{
			url:                   "https://foo/file1.html",
			expectedStatus:        http.StatusOK,
			expectedBodyContent:   testFiles[webrootFile1HTML],
			expectedEtag:          `"2n9cj"`,
			expectedContentLength: strconv.Itoa(len(testFiles[webrootFile1HTML])),
		},
		// Test 3 - access folder with index file with trailing slash
		{
			url:                   "https://foo/dirwithindex/",
			expectedStatus:        http.StatusOK,
			expectedBodyContent:   testFiles[webrootDirwithindexIndexHTML],
			expectedEtag:          `"2n9cw"`,
			expectedContentLength: strconv.Itoa(len(testFiles[webrootDirwithindexIndexHTML])),
		},
		// Test 4 - access folder with index file without trailing slash
		{
			url:                 "https://foo/dirwithindex",
			expectedStatus:      http.StatusMovedPermanently,
			expectedLocation:    "https://foo/dirwithindex/",
			expectedBodyContent: movedPermanently,
		},
		// Test 5 - access folder without index file
		{
			url:            "https://foo/dir/",
			expectedStatus: http.StatusNotFound,
		},
		// Test 6 - access folder without trailing slash
		{
			url:                 "https://foo/dir",
			expectedStatus:      http.StatusMovedPermanently,
			expectedLocation:    "https://foo/dir/",
			expectedBodyContent: movedPermanently,
		},
		// Test 7 - access file with trailing slash
		{
			url:                 "https://foo/file1.html/",
			expectedStatus:      http.StatusMovedPermanently,
			expectedLocation:    "https://foo/file1.html",
			expectedBodyContent: movedPermanently,
		},
		// Test 8 - access not existing path
		{
			url:            "https://foo/not_existing",
			expectedStatus: http.StatusNotFound,
		},
		// Test 9 - access a file, marked as hidden
		{
			url:            "https://foo/dir/hidden.html",
			expectedStatus: http.StatusNotFound,
		},
		// Test 10 - access an index file directly
		{
			url:              "https://foo/dirwithindex/index.html",
			expectedStatus:   http.StatusMovedPermanently,
			expectedLocation: "https://foo/dirwithindex/",
		},
		// Test 11 - access an index file with a trailing slash
		{
			url:              "https://foo/dirwithindex/index.html/",
			expectedStatus:   http.StatusMovedPermanently,
			expectedLocation: "https://foo/dirwithindex/",
		},
		// Test 12 - send a request with query params
		{
			url:                 "https://foo/dir?param1=val",
			expectedStatus:      http.StatusMovedPermanently,
			expectedLocation:    "https://foo/dir/?param1=val",
			expectedBodyContent: movedPermanently,
		},
		// Test 13 - attempt to bypass hidden file
		{
			url:            "https://foo/dir/hidden.html%20",
			expectedStatus: http.StatusNotFound,
		},
		// Test 14 - attempt to bypass hidden file
		{
			url:            "https://foo/dir/hidden.html.",
			expectedStatus: http.StatusNotFound,
		},
		// Test 15 - attempt to bypass hidden file
		{
			url:            "https://foo/dir/hidden.html.%20",
			expectedStatus: http.StatusNotFound,
		},
		// Test 16 - attempt to bypass hidden file
		{
			url:            "https://foo/dir/hidden.html%20.",
			acceptEncoding: "br, gzip",
			expectedStatus: http.StatusNotFound,
		},
		// Test 17 - serve another file with same name as hidden file.
		{
			url:            "https://foo/hidden.html",
			expectedStatus: http.StatusNotFound,
		},
		// Test 18 - try to get below the root directory.
		{
			url:            "https://foo/../unreachable.html",
			expectedStatus: http.StatusNotFound,
		},
		// Test 19 - try to get below the root directory (encoded slashes).
		{
			url:            "https://foo/..%2funreachable.html",
			expectedStatus: http.StatusNotFound,
		},
		// Test 20 - try to get pre-gzipped file.
		{
			url:                   "https://foo/sub/gzipped.html",
			acceptEncoding:        "gzip",
			expectedStatus:        http.StatusOK,
			expectedBodyContent:   testFiles[webrootSubGzippedHTMLGz],
			expectedEtag:          `"2n9ch"`,
			expectedVary:          "Accept-Encoding",
			expectedEncoding:      "gzip",
			expectedContentLength: strconv.Itoa(len(testFiles[webrootSubGzippedHTMLGz])),
		},
		// Test 21 - try to get pre-brotli encoded file.
		{
			url:                   "https://foo/sub/brotli.html",
			acceptEncoding:        "br,gzip",
			expectedStatus:        http.StatusOK,
			expectedBodyContent:   testFiles[webrootSubBrotliHTMLBr],
			expectedEtag:          `"2n9cg"`,
			expectedVary:          "Accept-Encoding",
			expectedEncoding:      "br",
			expectedContentLength: strconv.Itoa(len(testFiles[webrootSubBrotliHTMLBr])),
		},
		// Test 22 - not allowed to get pre-brotli encoded file.
		{
			url:                   "https://foo/sub/brotli.html",
			acceptEncoding:        "nicebrew", // contains "br" substring but not "br"
			expectedStatus:        http.StatusOK,
			expectedBodyContent:   testFiles[webrootSubBrotliHTML],
			expectedEtag:          `"2n9cd"`,
			expectedVary:          "",
			expectedEncoding:      "",
			expectedContentLength: strconv.Itoa(len(testFiles[webrootSubBrotliHTML])),
		},
		// Test 23 - treat existing file as a directory.
		{
			url:            "https://foo/file1.html/other",
			expectedStatus: http.StatusNotFound,
		},
		// Test 24 - access folder with index file without trailing slash, with stripped path
		{
			url:                 "https://foo/bar/dirwithindex",
			stripPathPrefix:     "/bar/",
			expectedStatus:      http.StatusMovedPermanently,
			expectedLocation:    "https://foo/bar/dirwithindex/",
			expectedBodyContent: movedPermanently,
		},
		// Test 25 - access folder with index file without trailing slash, with stripped path and query params
		{
			url:                 "https://foo/bar/dirwithindex?param1=val",
			stripPathPrefix:     "/bar/",
			expectedStatus:      http.StatusMovedPermanently,
			expectedLocation:    "https://foo/bar/dirwithindex/?param1=val",
			expectedBodyContent: movedPermanently,
		},
		// Test 26 - site defined with path ("bar"), which has that prefix stripped
		{
			url:                 "https://foo/bar/file1.html/",
			stripPathPrefix:     "/bar/",
			expectedStatus:      http.StatusMovedPermanently,
			expectedLocation:    "https://foo/bar/file1.html",
			expectedBodyContent: movedPermanently,
		},
		{
			// Test 27 - Check etag
			url:                   "https://foo/notindex.html",
			expectedStatus:        http.StatusOK,
			expectedBodyContent:   testFiles[webrootNotIndexHTML],
			expectedEtag:          `"2n9cm"`,
			expectedContentLength: strconv.Itoa(len(testFiles[webrootNotIndexHTML])),
		},
		{
			// Test 28 - Prevent path-based open redirects (directory)
			url:                 "https://foo//example.com%2f..",
			expectedStatus:      http.StatusMovedPermanently,
			expectedLocation:    "https://foo/example.com/../",
			expectedBodyContent: movedPermanently,
		},
		{
			// Test 29 - Prevent path-based open redirects (file)
			url:                 "https://foo//example.com%2f../dirwithindex/index.html",
			expectedStatus:      http.StatusMovedPermanently,
			expectedLocation:    "https://foo/example.com/../dirwithindex/",
			expectedBodyContent: movedPermanently,
		},
		{
			// Test 29 - Prevent path-based open redirects (extra leading slashes)
			url:                 "https://foo///example.com%2f..",
			expectedStatus:      http.StatusMovedPermanently,
			expectedLocation:    "https://foo/example.com/../",
			expectedBodyContent: movedPermanently,
		},
		// Test 30 - try to get pre- file.
		{
			url:                   "https://foo/sub/gzipped.html",
			acceptEncoding:        "zstd",
			expectedStatus:        http.StatusOK,
			expectedBodyContent:   testFiles[webrootSubGzippedHTMLZst],
			expectedEtag:          `"2n9ci"`,
			expectedVary:          "Accept-Encoding",
			expectedEncoding:      "zstd",
			expectedContentLength: strconv.Itoa(len(testFiles[webrootSubGzippedHTMLZst])),
		},
	}

	for i, test := range tests {
		// set up response writer and request
		responseRecorder := httptest.NewRecorder()
		request, err := http.NewRequest("GET", test.url, nil)
		if err != nil {
			t.Errorf("Test %d: Error making request: %v", i, err)
			continue
		}

		// set the original URL and path prefix on the context
		ctx := context.WithValue(request.Context(), caddy.CtxKey("original_url"), *request.URL)
		request = request.WithContext(ctx)
		ctx = context.WithValue(request.Context(), caddy.CtxKey("path_prefix"), test.stripPathPrefix)
		request = request.WithContext(ctx)

		request.Header.Add("Accept-Encoding", test.acceptEncoding)

		// simulate cases where a site is defined with a path prefix (e.g. "localhost/foo/")
		if test.stripPathPrefix != "" {
			request.URL.Path = strings.TrimPrefix(request.URL.Path, test.stripPathPrefix)
		}

		// perform the test
		status, err := fileServer.ServeHTTP(responseRecorder, request)
		if status == 0 {
			status = responseRecorder.Code
		}
		etag := responseRecorder.Header().Get("Etag")
		body := responseRecorder.Body.String()
		vary := responseRecorder.Header().Get("Vary")
		encoding := responseRecorder.Header().Get("Content-Encoding")
		length := responseRecorder.Header().Get("Content-Length")

		// check if error matches expectations
		if err != nil {
			t.Errorf("Test %d: Serving file at %s failed. Error was: %v", i, test.url, err)
		}

		// check status code
		if test.expectedStatus != status {
			t.Errorf("Test %d: Expected status %d, found %d", i, test.expectedStatus, status)
		}

		// check etag
		if test.expectedEtag != etag {
			t.Errorf("Test %d: Expected Etag header %s, found %s", i, test.expectedEtag, etag)
		}

		// check vary
		if test.expectedVary != vary {
			t.Errorf("Test %d: Expected Vary header %s, found %s", i, test.expectedVary, vary)
		}

		// check content-encoding
		if test.expectedEncoding != encoding {
			t.Errorf("Test %d: Expected Content-Encoding header %s, found %s", i, test.expectedEncoding, encoding)
		}

		// check body content
		if !strings.Contains(body, test.expectedBodyContent) {
			t.Errorf("Test %d: Expected body to contain %q, found %q", i, test.expectedBodyContent, body)
		}

		// check Location header
		if test.expectedLocation != "" {
			l := responseRecorder.Header().Get("Location")
			if test.expectedLocation != l {
				t.Errorf("Test %d: Expected Location header %q, found %q", i, test.expectedLocation, l)
			}
		}

		// check content length
		if test.expectedContentLength != length {
			t.Errorf("Test %d: Expected Content-Length header %s, found %s", i, test.expectedContentLength, length)
		}
	}

}

// beforeServeHTTPTest creates a test directory with the structure, defined in the variable testFiles
func beforeServeHTTPTest(t *testing.T) string {
	tmpdir, err := ioutil.TempDir("", testDirPrefix)
	if err != nil {
		t.Fatalf("failed to create test directory: %v", err)
	}

	fixedTime := time.Unix(123456, 0)

	for relFile, fileContent := range testFiles {
		absFile := filepath.Join(tmpdir, relFile)

		// make sure the parent directories exist
		parentDir := filepath.Dir(absFile)
		_, err = os.Stat(parentDir)
		if err != nil {
			if err := os.MkdirAll(parentDir, os.ModePerm); err != nil {
				log.Println("[ERROR] MkdirAll failed: ", err)
			}
		}

		// now create the test files
		f, err := os.Create(absFile)
		if err != nil {
			t.Fatalf("Failed to create test file %s. Error was: %v", absFile, err)
		}

		// and fill them with content
		_, err = f.WriteString(fileContent)
		if err != nil {
			t.Fatalf("Failed to write to %s. Error was: %v", absFile, err)
		}
		_ = f.Close()

		// and set the last modified time
		err = os.Chtimes(absFile, fixedTime, fixedTime)
		if err != nil {
			t.Fatalf("Failed to set file time to %s. Error was: %v", fixedTime, err)
		}
	}

	return tmpdir
}

// afterServeHTTPTest removes the test dir and all its content
func afterServeHTTPTest(t *testing.T, webroot string) {
	if !strings.Contains(webroot, testDirPrefix) {
		t.Fatalf("Cannot clean up after test because webroot is: %s", webroot)
	}
	// cleans up everything under the test dir. No need to clean the individual files.
	err := os.RemoveAll(webroot)
	if err != nil {
		t.Fatalf("Failed to clean up test dir %s. Error was: %v", webroot, err)
	}
}

// failingFS implements the http.FileSystem interface. The Open method always returns the error, assigned to err
type failingFS struct {
	err      error     // the error to return when Open is called
	fileImpl http.File // inject the file implementation
}

// Open returns the assigned failingFile and error
func (f failingFS) Open(path string) (http.File, error) {
	return f.fileImpl, f.err
}

// failingFile implements http.File but returns a predefined error on every Stat() method call.
type failingFile struct {
	http.File
	err error
}

// Stat returns nil FileInfo and the provided error on every call
func (ff failingFile) Stat() (os.FileInfo, error) {
	return nil, ff.err
}

// Close is noop and returns no error
func (ff failingFile) Close() error {
	return nil
}

// TestServeHTTPFailingFS tests error cases where the Open
// function fails with various errors.
func TestServeHTTPFailingFS(t *testing.T) {
	tests := []struct {
		fsErr           error
		expectedStatus  int
		expectedErr     error
		expectedHeaders map[string]struct{}
	}{
		{
			fsErr:          os.ErrNotExist,
			expectedStatus: http.StatusNotFound,
			expectedErr:    nil,
		},
		{
			fsErr:          os.ErrPermission,
			expectedStatus: http.StatusForbidden,
			expectedErr:    os.ErrPermission,
		},
		{
			fsErr:           errCustom,
			expectedStatus:  http.StatusServiceUnavailable,
			expectedErr:     errCustom,
			expectedHeaders: map[string]struct{}{"Retry-After": {}},
		},
	}

	for i, test := range tests {
		// initialize a file server with the failing FileSystem
		fileserver := FileServer{Root: failingFS{err: test.fsErr}}

		// prepare the request and response
		request, err := http.NewRequest("GET", "https://foo/", nil)
		if err != nil {
			t.Fatalf("Failed to build request. Error was: %v", err)
		}
		responseRecorder := httptest.NewRecorder()

		status, actualErr := fileserver.ServeHTTP(responseRecorder, request)

		// check the status
		if status != test.expectedStatus {
			t.Errorf("Test %d: Expected status %d, found %d", i, test.expectedStatus, status)
		}

		// check the error
		if actualErr != test.expectedErr {
			t.Errorf("Test %d: Expected err %v, found %v", i, test.expectedErr, actualErr)
		}

		// check the headers - a special case for server under load
		if test.expectedHeaders != nil && len(test.expectedHeaders) > 0 {
			for expectedKey := range test.expectedHeaders {
				if _, ok := responseRecorder.Header()[expectedKey]; !ok {
					t.Errorf("Test %d: Expected header %s, but was missing", i, expectedKey)
				}
			}
		}
	}
}

// TestServeHTTPFailingStat tests error cases where the initial Open function succeeds,
// but the Stat method on the opened file fails.
func TestServeHTTPFailingStat(t *testing.T) {
	tests := []struct {
		statErr        error
		expectedStatus int
		expectedErr    error
	}{
		{
			statErr:        os.ErrNotExist,
			expectedStatus: http.StatusNotFound,
			expectedErr:    nil,
		},
		{
			statErr:        os.ErrPermission,
			expectedStatus: http.StatusForbidden,
			expectedErr:    os.ErrPermission,
		},
		{
			statErr:        errCustom,
			expectedStatus: http.StatusInternalServerError,
			expectedErr:    errCustom,
		},
	}

	for i, test := range tests {
		// initialize a file server. The FileSystem will not fail, but calls to the Stat method of the returned File object will
		fileServer := FileServer{Root: failingFS{err: nil, fileImpl: failingFile{err: test.statErr}}}

		// prepare the request and response
		request, err := http.NewRequest("GET", "https://foo/", nil)
		if err != nil {
			t.Fatalf("Failed to build request. Error was: %v", err)
		}
		responseRecorder := httptest.NewRecorder()

		status, actualErr := fileServer.ServeHTTP(responseRecorder, request)

		// check the status
		if status != test.expectedStatus {
			t.Errorf("Test %d: Expected status %d, found %d", i, test.expectedStatus, status)
		}

		// check the error
		if actualErr != test.expectedErr {
			t.Errorf("Test %d: Expected err %v, found %v", i, test.expectedErr, actualErr)
		}
	}
}

// Paths for the fake site used temporarily during testing.
var (
	webrootFile1HTML                   = filepath.Join(webrootName, "file1.html")
	webrootNotIndexHTML                = filepath.Join(webrootName, "notindex.html")
	webrootDirFile2HTML                = filepath.Join(webrootName, "dir", "file2.html")
	webrootDirHiddenHTML               = filepath.Join(webrootName, "dir", "hidden.html")
	webrootDirwithindexIndexHTML       = filepath.Join(webrootName, "dirwithindex", "index.html")
	webrootSubGzippedHTML              = filepath.Join(webrootName, "sub", "gzipped.html")
	webrootSubGzippedHTMLGz            = filepath.Join(webrootName, "sub", "gzipped.html.gz")
	webrootSubGzippedHTMLBr            = filepath.Join(webrootName, "sub", "gzipped.html.br")
	webrootSubGzippedHTMLZst           = filepath.Join(webrootName, "sub", "gzipped.html.zst")
	webrootSubBrotliHTML               = filepath.Join(webrootName, "sub", "brotli.html")
	webrootSubBrotliHTMLGz             = filepath.Join(webrootName, "sub", "brotli.html.gz")
	webrootSubBrotliHTMLBr             = filepath.Join(webrootName, "sub", "brotli.html.br")
	webrootSubBarDirWithIndexIndexHTML = filepath.Join(webrootName, "bar", "dirwithindex", "index.html")
)

// testFiles is a map with relative paths to test files as keys and file content as values.
// The map represents the following structure:
// - $TEMP/caddy_testdir/
// '-- unreachable.html
// '-- webroot/
// '---- file1.html
// '---- dirwithindex/
// '------ index.html
// '---- dir/
// '------ file2.html
// '------ hidden.html
var testFiles = map[string]string{
	"unreachable.html":                 "<h1>must not leak</h1>",
	webrootFile1HTML:                   "<h1>file1.html</h1>",
	webrootNotIndexHTML:                "<h1>notindex.html</h1>",
	webrootDirFile2HTML:                "<h1>dir/file2.html</h1>",
	webrootDirwithindexIndexHTML:       "<h1>dirwithindex/index.html</h1>",
	webrootDirHiddenHTML:               "<h1>dir/hidden.html</h1>",
	webrootSubGzippedHTML:              "<h1>gzipped.html</h1>",
	webrootSubGzippedHTMLGz:            "1.gzipped.html.gz",
	webrootSubGzippedHTMLBr:            "2.gzipped.html.br",
	webrootSubGzippedHTMLZst:           "3.gzipped.html.zst",
	webrootSubBrotliHTML:               "4.brotli.html",
	webrootSubBrotliHTMLGz:             "5.brotli.html.gz",
	webrootSubBrotliHTMLBr:             "6.brotli.html.br",
	webrootSubBarDirWithIndexIndexHTML: "<h1>bar/dirwithindex/index.html</h1>",
}

var errCustom = errors.New("custom error")

const (
	testDirPrefix = "caddy_fileserver_test"
	webrootName   = "webroot" // name of the folder inside the tmp dir that has the site
)

//-------------------------------------------------------------------------------------------------

type fileInfo struct {
	name    string
	size    int64
	mode    os.FileMode
	modTime time.Time
	isDir   bool
}

func (fi fileInfo) Name() string {
	return fi.name
}

func (fi fileInfo) Size() int64 {
	return fi.size
}

func (fi fileInfo) Mode() os.FileMode {
	return fi.mode
}

func (fi fileInfo) ModTime() time.Time {
	return fi.modTime
}

func (fi fileInfo) IsDir() bool {
	return fi.isDir
}

func (fi fileInfo) Sys() interface{} {
	return nil
}

var _ os.FileInfo = fileInfo{}

func BenchmarkEtag(b *testing.B) {
	d := fileInfo{
		size:    1234567890,
		modTime: time.Now(),
	}

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		calculateEtag(d)
	}
}
