// Copyright 2018 Google 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 httpreplay_test

import (
	"bytes"
	"context"
	"encoding/json"
	"io/ioutil"
	"net/http"
	"os"
	"testing"
	"time"

	"cloud.google.com/go/httpreplay"
	"cloud.google.com/go/internal/testutil"
	"cloud.google.com/go/storage"
	"google.golang.org/api/option"
)

func TestIntegration_RecordAndReplay(t *testing.T) {
	httpreplay.DebugHeaders()
	if testing.Short() {
		t.Skip("Integration tests skipped in short mode")
	}
	f, err := ioutil.TempFile("", "httpreplay")
	if err != nil {
		t.Fatal(err)
	}
	replayFilename := f.Name()
	if err := f.Close(); err != nil {
		t.Fatal(err)
	}
	defer os.Remove(replayFilename)
	projectID := testutil.ProjID()
	if projectID == "" {
		t.Skip("Need project ID. See CONTRIBUTING.md for details.")
	}
	ctx := context.Background()

	// Record.
	initial := time.Now()
	ibytes, err := json.Marshal(initial)
	if err != nil {
		t.Fatal(err)
	}
	rec, err := httpreplay.NewRecorder(replayFilename, ibytes)
	if err != nil {
		t.Fatal(err)
	}
	hc, err := rec.Client(ctx, option.WithTokenSource(
		testutil.TokenSource(ctx, storage.ScopeFullControl)))
	if err != nil {
		t.Fatal(err)
	}
	wanta, wantc := run(t, hc)
	testReadCRC(t, hc, "recording")
	if err := rec.Close(); err != nil {
		t.Fatalf("rec.Close: %v", err)
	}

	// Replay.
	rep, err := httpreplay.NewReplayer(replayFilename)
	if err != nil {
		t.Fatal(err)
	}
	defer rep.Close()
	hc, err = rep.Client(ctx)
	if err != nil {
		t.Fatal(err)
	}
	gota, gotc := run(t, hc)
	testReadCRC(t, hc, "replaying")

	if diff := testutil.Diff(gota, wanta); diff != "" {
		t.Error(diff)
	}
	if !bytes.Equal(gotc, wantc) {
		t.Errorf("got %q, want %q", gotc, wantc)
	}
	var gotInitial time.Time
	if err := json.Unmarshal(rep.Initial(), &gotInitial); err != nil {
		t.Fatal(err)
	}
	if !gotInitial.Equal(initial) {
		t.Errorf("initial: got %v, want %v", gotInitial, initial)
	}
}

// TODO(jba): test errors

func run(t *testing.T, hc *http.Client) (*storage.BucketAttrs, []byte) {
	ctx := context.Background()
	client, err := storage.NewClient(ctx, option.WithHTTPClient(hc))
	if err != nil {
		t.Fatal(err)
	}
	defer client.Close()
	b := client.Bucket(testutil.ProjID())
	attrs, err := b.Attrs(ctx)
	if err != nil {
		t.Fatal(err)
	}
	obj := b.Object("replay-test")
	w := obj.NewWriter(ctx)
	data := []byte{150, 151, 152}
	if _, err := w.Write(data); err != nil {
		t.Fatal(err)
	}
	if err := w.Close(); err != nil {
		t.Fatal(err)
	}

	r, err := obj.NewReader(ctx)
	if err != nil {
		t.Fatal(err)
	}
	defer r.Close()
	contents, err := ioutil.ReadAll(r)
	if err != nil {
		t.Fatal(err)
	}

	return attrs, contents
}

func testReadCRC(t *testing.T, hc *http.Client, mode string) {
	const (
		// This is an uncompressed file.
		// See https://cloud.google.com/storage/docs/public-datasets/landsat
		uncompressedBucket = "gcp-public-data-landsat"
		uncompressedObject = "LC08/PRE/044/034/LC80440342016259LGN00/LC80440342016259LGN00_MTL.txt"

		gzippedBucket   = "storage-library-test-bucket"
		gzippedObject   = "gzipped-text.txt"
		gzippedContents = "hello world" // uncompressed contents of the file
	)
	ctx := context.Background()
	client, err := storage.NewClient(ctx, option.WithHTTPClient(hc))
	if err != nil {
		t.Fatalf("%s: %v", mode, err)
	}
	defer client.Close()

	uncompressedObj := client.Bucket(uncompressedBucket).Object(uncompressedObject)
	gzippedObj := client.Bucket(gzippedBucket).Object(gzippedObject)

	for _, test := range []struct {
		desc           string
		obj            *storage.ObjectHandle
		offset, length int64
		readCompressed bool // don't decompress a gzipped file

		wantErr bool
		wantLen int // length of contents
	}{
		{
			desc:           "uncompressed, entire file",
			obj:            uncompressedObj,
			offset:         0,
			length:         -1,
			readCompressed: false,
			wantLen:        7903,
		},
		{
			desc:           "uncompressed, entire file, don't decompress",
			obj:            uncompressedObj,
			offset:         0,
			length:         -1,
			readCompressed: true,
			wantLen:        7903,
		},
		{
			desc:           "uncompressed, suffix",
			obj:            uncompressedObj,
			offset:         3,
			length:         -1,
			readCompressed: false,
			wantLen:        7900,
		},
		{
			desc:           "uncompressed, prefix",
			obj:            uncompressedObj,
			offset:         0,
			length:         18,
			readCompressed: false,
			wantLen:        18,
		},
		{
			// When a gzipped file is unzipped by GCS, we can't verify the checksum
			// because it was computed against the zipped contents. There is no
			// header that indicates that a gzipped file is being served unzipped.
			// But our CRC check only happens if there is a Content-Length header,
			// and that header is absent for this read.
			desc:           "compressed, entire file, server unzips",
			obj:            gzippedObj,
			offset:         0,
			length:         -1,
			readCompressed: false,
			wantLen:        11,
		},
		{
			// When we read a gzipped file uncompressed, it's like reading a regular file:
			// the served content and the CRC match.
			desc:           "compressed, entire file, read compressed",
			obj:            gzippedObj,
			offset:         0,
			length:         -1,
			readCompressed: true,
			wantLen:        31,
		},
		{
			desc:           "compressed, partial, read compressed",
			obj:            gzippedObj,
			offset:         1,
			length:         8,
			readCompressed: true,
			wantLen:        8,
		},
		{
			desc:    "uncompressed, HEAD",
			obj:     uncompressedObj,
			offset:  0,
			length:  0,
			wantLen: 0,
		},
		{
			desc:    "compressed, HEAD",
			obj:     gzippedObj,
			offset:  0,
			length:  0,
			wantLen: 0,
		},
	} {
		obj := test.obj.ReadCompressed(test.readCompressed)
		r, err := obj.NewRangeReader(ctx, test.offset, test.length)
		if err != nil {
			if test.wantErr {
				continue
			}
			t.Errorf("%s: %s: %v", mode, test.desc, err)
			continue
		}
		data, err := ioutil.ReadAll(r)
		_ = r.Close()
		if err != nil {
			t.Errorf("%s: %s: %v", mode, test.desc, err)
			continue
		}
		if got, want := len(data), test.wantLen; got != want {
			t.Errorf("%s: %s: len: got %d, want %d", mode, test.desc, got, want)
		}
	}
}