package starlog

import (
	"bytes"
	"context"
	"errors"
	"path/filepath"
	"sync/atomic"
	"testing"
	"time"
)

type syncWriteBuffer struct {
	bytes.Buffer
	syncCalls uint64
}

func (buffer *syncWriteBuffer) Sync() error {
	atomic.AddUint64(&buffer.syncCalls, 1)
	return nil
}

type closeSink struct {
	closeCalls uint64
}

func (sink *closeSink) Write(data []byte) error {
	_ = data
	return nil
}

func (sink *closeSink) Close() error {
	atomic.AddUint64(&sink.closeCalls, 1)
	return nil
}

func TestFlushDrainsPendingWrites(t *testing.T) {
	var output bytes.Buffer
	logger := newStructuredTestLogger(&output)
	logger.SetSwitching(true)
	logger.Infoln("pending")

	if output.Len() != 0 {
		t.Fatalf("pending logs should not be written while switching=true")
	}
	if err := logger.Flush(); err != nil {
		t.Fatalf("Flush failed: %v", err)
	}
	if output.Len() == 0 {
		t.Fatalf("Flush should write buffered logs")
	}
}

func TestSyncCallsWriterSync(t *testing.T) {
	var writer syncWriteBuffer
	logger := NewStarlog(&writer)
	logger.SetShowStd(false)
	logger.SetShowColor(false)
	logger.SetShowOriginFile(false)
	logger.SetShowFuncName(false)
	logger.SetShowFlag(false)

	logger.Infoln("sync")
	if err := logger.Sync(); err != nil {
		t.Fatalf("Sync failed: %v", err)
	}
	if atomic.LoadUint64(&writer.syncCalls) == 0 {
		t.Fatalf("Sync should call underlying writer Sync method")
	}
}

func TestCloseClosesSinkAndStopsWrite(t *testing.T) {
	sink := &closeSink{}
	logger := NewStarlog(nil)
	logger.SetShowStd(false)
	logger.SetShowColor(false)
	logger.SetShowOriginFile(false)
	logger.SetShowFuncName(false)
	logger.SetShowFlag(false)
	logger.SetSink(sink)

	if err := logger.Close(); err != nil {
		t.Fatalf("Close failed: %v", err)
	}
	if atomic.LoadUint64(&sink.closeCalls) == 0 {
		t.Fatalf("Close should call sink.Close")
	}
	if !logger.IsWriteStopped() {
		t.Fatalf("Close should stop writer")
	}
}

func TestWaitAsyncDrainContextTimeout(t *testing.T) {
	stackMu.Lock()
	stackStarted = true
	stacks = newStarChanStack(1)
	stackStopChan = nil
	stackDoneChan = nil
	stackMu.Unlock()
	defer func() {
		stackMu.Lock()
		if stacks != nil {
			_ = stacks.Close()
		}
		stackStarted = false
		stacks = nil
		stackStopChan = nil
		stackDoneChan = nil
		stackMu.Unlock()
	}()

	if err := stacks.Push("x"); err != nil {
		t.Fatalf("prepare queue failed: %v", err)
	}
	ctx, cancel := context.WithTimeout(context.Background(), 20*time.Millisecond)
	defer cancel()
	err := WaitAsyncDrain(ctx)
	if !errors.Is(err, context.DeadlineExceeded) {
		t.Fatalf("WaitAsyncDrain should return context deadline, got %v", err)
	}
}

func TestShutdownStopsAsyncStacks(t *testing.T) {
	resetAsyncMetricsForTest()
	defer func() {
		resetAsyncMetricsForTest()
		StopStacks()
	}()

	logger := NewStarlog(nil)
	logger.SetShowStd(false)
	handled := make(chan struct{}, 1)
	logger.SetHandler(func(LogData) {
		select {
		case handled <- struct{}{}:
		default:
		}
	})
	logger.Infoln("shutdown")

	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
	defer cancel()
	if err := logger.Shutdown(ctx); err != nil {
		t.Fatalf("Shutdown failed: %v", err)
	}
	select {
	case <-handled:
	case <-time.After(200 * time.Millisecond):
		t.Fatalf("async handler should complete before shutdown")
	}

	stackMu.Lock()
	started := stackStarted
	stackMu.Unlock()
	if started {
		t.Fatalf("Shutdown should stop async stacks")
	}
}

func TestCloseManagedLogFileNoDoubleCloseError(t *testing.T) {
	logger := NewStarlog(nil)
	logger.SetShowStd(false)
	logPath := filepath.Join(testBinDir(t), "lifecycle_close.log")
	if err := SetLogFile(logPath, logger, false); err != nil {
		t.Fatalf("SetLogFile failed: %v", err)
	}
	if err := logger.Close(); err != nil {
		t.Fatalf("Close should not fail for managed log file: %v", err)
	}
}