package local

import (
	"bytes"
	"context"
	"encoding/binary"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"github.com/docker/docker/api/types/backend"
	"github.com/docker/docker/api/types/plugins/logdriver"
	"github.com/docker/docker/daemon/logger"
	protoio "github.com/gogo/protobuf/io"
	"gotest.tools/v3/assert"
	is "gotest.tools/v3/assert/cmp"
)

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

	dir, err := os.MkdirTemp("", t.Name())
	assert.NilError(t, err)
	defer os.RemoveAll(dir)

	logPath := filepath.Join(dir, "test.log")

	l, err := New(logger.Info{LogPath: logPath})
	assert.NilError(t, err)
	defer l.Close()

	m1 := logger.Message{Source: "stdout", Timestamp: time.Now().Add(-1 * 30 * time.Minute), Line: []byte("message 1")}
	m2 := logger.Message{Source: "stdout", Timestamp: time.Now().Add(-1 * 20 * time.Minute), Line: []byte("message 2"), PLogMetaData: &backend.PartialLogMetaData{Last: true, ID: "0001", Ordinal: 1}}
	m3 := logger.Message{Source: "stderr", Timestamp: time.Now().Add(-1 * 10 * time.Minute), Line: []byte("message 3")}

	// copy the log message because the underying log writer resets the log message and returns it to a buffer pool
	err = l.Log(copyLogMessage(&m1))
	assert.NilError(t, err)
	err = l.Log(copyLogMessage(&m2))
	assert.NilError(t, err)
	err = l.Log(copyLogMessage(&m3))
	assert.NilError(t, err)

	f, err := os.Open(logPath)
	assert.NilError(t, err)
	defer f.Close()
	dec := protoio.NewUint32DelimitedReader(f, binary.BigEndian, 1e6)

	var (
		proto     logdriver.LogEntry
		testProto logdriver.LogEntry
		partial   logdriver.PartialLogEntryMetadata
	)

	lenBuf := make([]byte, encodeBinaryLen)
	seekMsgLen := func() {
		io.ReadFull(f, lenBuf)
	}

	err = dec.ReadMsg(&proto)
	assert.NilError(t, err)
	messageToProto(&m1, &testProto, &partial)
	assert.Check(t, is.DeepEqual(testProto, proto), "expected:\n%+v\ngot:\n%+v", testProto, proto)
	seekMsgLen()

	err = dec.ReadMsg(&proto)
	assert.NilError(t, err)
	messageToProto(&m2, &testProto, &partial)
	assert.Check(t, is.DeepEqual(testProto, proto))
	seekMsgLen()

	err = dec.ReadMsg(&proto)
	assert.NilError(t, err)
	messageToProto(&m3, &testProto, &partial)
	assert.Check(t, is.DeepEqual(testProto, proto), "expected:\n%+v\ngot:\n%+v", testProto, proto)
}

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

	dir, err := os.MkdirTemp("", t.Name())
	assert.NilError(t, err)
	defer os.RemoveAll(dir)

	logPath := filepath.Join(dir, "test.log")
	l, err := New(logger.Info{LogPath: logPath})
	assert.NilError(t, err)
	defer l.Close()

	m1 := logger.Message{Source: "stdout", Timestamp: time.Now().Add(-1 * 30 * time.Minute), Line: []byte("a message")}
	m2 := logger.Message{Source: "stdout", Timestamp: time.Now().Add(-1 * 20 * time.Minute), Line: []byte("another message"), PLogMetaData: &backend.PartialLogMetaData{Ordinal: 1, Last: true}}
	longMessage := []byte("a really long message " + strings.Repeat("a", initialBufSize*2))
	m3 := logger.Message{Source: "stderr", Timestamp: time.Now().Add(-1 * 10 * time.Minute), Line: longMessage}
	m4 := logger.Message{Source: "stderr", Timestamp: time.Now().Add(-1 * 10 * time.Minute), Line: []byte("just one more message")}

	// copy the log message because the underlying log writer resets the log message and returns it to a buffer pool
	err = l.Log(copyLogMessage(&m1))
	assert.NilError(t, err)
	err = l.Log(copyLogMessage(&m2))
	assert.NilError(t, err)
	err = l.Log(copyLogMessage(&m3))
	assert.NilError(t, err)
	err = l.Log(copyLogMessage(&m4))
	assert.NilError(t, err)

	lr := l.(logger.LogReader)

	testMessage := func(t *testing.T, lw *logger.LogWatcher, m *logger.Message) {
		t.Helper()
		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
		defer cancel()
		select {
		case <-ctx.Done():
			assert.Assert(t, ctx.Err())
		case err := <-lw.Err:
			assert.NilError(t, err)
		case msg, open := <-lw.Msg:
			if !open {
				select {
				case err := <-lw.Err:
					assert.NilError(t, err)
				default:
					assert.Assert(t, m == nil)
					return
				}
			}
			assert.Assert(t, m != nil)
			if m.PLogMetaData == nil {
				// a `\n` is appended on read to make this work with the existing API's when the message is not a partial.
				// make sure it's the last entry in the line, and then truncate it for the deep equal below.
				assert.Check(t, msg.Line[len(msg.Line)-1] == '\n')
				msg.Line = msg.Line[:len(msg.Line)-1]
			}
			assert.Check(t, is.DeepEqual(m, msg), fmt.Sprintf("\n%+v\n%+v", m, msg))
		}
	}

	t.Run("tail exact", func(t *testing.T) {
		lw := lr.ReadLogs(logger.ReadConfig{Tail: 4})

		testMessage(t, lw, &m1)
		testMessage(t, lw, &m2)
		testMessage(t, lw, &m3)
		testMessage(t, lw, &m4)
		testMessage(t, lw, nil) // no more messages
	})

	t.Run("tail less than available", func(t *testing.T) {
		lw := lr.ReadLogs(logger.ReadConfig{Tail: 2})

		testMessage(t, lw, &m3)
		testMessage(t, lw, &m4)
		testMessage(t, lw, nil) // no more messages
	})

	t.Run("tail more than available", func(t *testing.T) {
		lw := lr.ReadLogs(logger.ReadConfig{Tail: 100})

		testMessage(t, lw, &m1)
		testMessage(t, lw, &m2)
		testMessage(t, lw, &m3)
		testMessage(t, lw, &m4)
		testMessage(t, lw, nil) // no more messages
	})
}

func BenchmarkLogWrite(b *testing.B) {
	f, err := os.CreateTemp("", b.Name())
	assert.Assert(b, err)
	defer os.Remove(f.Name())
	f.Close()

	local, err := New(logger.Info{LogPath: f.Name()})
	assert.Assert(b, err)
	defer local.Close()

	t := time.Now().UTC()
	for _, data := range [][]byte{
		[]byte(""),
		[]byte("a short string"),
		bytes.Repeat([]byte("a long string"), 100),
		bytes.Repeat([]byte("a really long string"), 10000),
	} {
		b.Run(fmt.Sprintf("%d", len(data)), func(b *testing.B) {
			entry := &logdriver.LogEntry{Line: data, Source: "stdout", TimeNano: t.UnixNano()}
			b.SetBytes(int64(entry.Size() + encodeBinaryLen + encodeBinaryLen))
			b.ResetTimer()
			for i := 0; i < b.N; i++ {
				msg := logger.NewMessage()
				msg.Line = data
				msg.Timestamp = t
				msg.Source = "stdout"
				if err := local.Log(msg); err != nil {
					b.Fatal(err)
				}
			}
		})
	}
}

func copyLogMessage(src *logger.Message) *logger.Message {
	dst := logger.NewMessage()
	dst.Source = src.Source
	dst.Timestamp = src.Timestamp
	dst.Attrs = src.Attrs
	dst.Err = src.Err
	dst.Line = append(dst.Line, src.Line...)
	if src.PLogMetaData != nil {
		lmd := *src.PLogMetaData
		dst.PLogMetaData = &lmd
	}
	return dst
}