package stario

import (
	"bytes"
	"context"
	"errors"
	"io"
	"testing"
	"time"
)

func TestQueueBuildMessageUsesVersionedHeader(t *testing.T) {
	que := NewQueue()
	frame := que.BuildMessage([]byte("hello"))

	if len(frame) != queHeaderSize+5 {
		t.Fatalf("unexpected frame length: got %d want %d", len(frame), queHeaderSize+5)
	}
	if !bytes.Equal(frame[:queMagicSize], queMagic) {
		t.Fatalf("unexpected magic: %v", frame[:queMagicSize])
	}
	if got := ByteToUint32(frame[queMagicSize : queMagicSize+4]); got != 5 {
		t.Fatalf("unexpected payload length: got %d want 5", got)
	}
	if frame[12] != queVersionV1 {
		t.Fatalf("unexpected version: got %d want %d", frame[12], queVersionV1)
	}
	if frame[13] != queSupportedFlags {
		t.Fatalf("unexpected flags: got %d want %d", frame[13], queSupportedFlags)
	}
	if !bytes.Equal(frame[queHeaderSize:], []byte("hello")) {
		t.Fatalf("unexpected payload: %q", frame[queHeaderSize:])
	}
}

func TestQueueWriteFrameMatchesBuildMessage(t *testing.T) {
	que := NewQueue()
	want := que.BuildMessage([]byte("hello"))

	var buf bytes.Buffer
	if err := que.WriteFrame(&buf, []byte("hello")); err != nil {
		t.Fatalf("WriteFrame failed: %v", err)
	}
	if got := buf.Bytes(); !bytes.Equal(got, want) {
		t.Fatalf("WriteFrame mismatch: got %v want %v", got, want)
	}
}

func TestQueueWriteFrameBuffersMatchesBuildMessage(t *testing.T) {
	que := NewQueue()
	want := que.BuildMessage([]byte("hello"))

	var buf bytes.Buffer
	if err := que.WriteFrameBuffers(&buf, []byte("hello")); err != nil {
		t.Fatalf("WriteFrameBuffers failed: %v", err)
	}
	if got := buf.Bytes(); !bytes.Equal(got, want) {
		t.Fatalf("WriteFrameBuffers mismatch: got %v want %v", got, want)
	}
}

func TestQueueWriteFramesBuffersMatchesBuildMessage(t *testing.T) {
	que := NewQueue()
	payloads := [][]byte{
		[]byte("hello"),
		[]byte("world"),
		[]byte("batch"),
	}

	var want []byte
	for _, payload := range payloads {
		want = append(want, que.BuildMessage(payload)...)
	}

	var buf bytes.Buffer
	if err := que.WriteFramesBuffers(&buf, payloads...); err != nil {
		t.Fatalf("WriteFramesBuffers failed: %v", err)
	}
	if got := buf.Bytes(); !bytes.Equal(got, want) {
		t.Fatalf("WriteFramesBuffers mismatch: got %v want %v", got, want)
	}
}

func TestQueueWriteFrameHonorsEncodeFunc(t *testing.T) {
	que := NewQueue()
	que.Encode = true
	que.EncodeFunc = bytes.ToUpper
	want := que.BuildMessage([]byte("hello"))

	var buf bytes.Buffer
	if err := que.WriteFrame(&buf, []byte("hello")); err != nil {
		t.Fatalf("WriteFrame failed: %v", err)
	}
	if got := buf.Bytes(); !bytes.Equal(got, want) {
		t.Fatalf("WriteFrame mismatch with EncodeFunc: got %v want %v", got, want)
	}
}

func TestQueueWriteFrameBuffersHonorsEncodeFunc(t *testing.T) {
	que := NewQueue()
	que.Encode = true
	que.EncodeFunc = bytes.ToUpper
	want := que.BuildMessage([]byte("hello"))

	var buf bytes.Buffer
	if err := que.WriteFrameBuffers(&buf, []byte("hello")); err != nil {
		t.Fatalf("WriteFrameBuffers failed: %v", err)
	}
	if got := buf.Bytes(); !bytes.Equal(got, want) {
		t.Fatalf("WriteFrameBuffers mismatch with EncodeFunc: got %v want %v", got, want)
	}
}

func TestQueueWriteFramesBuffersHonorsEncodeFunc(t *testing.T) {
	que := NewQueue()
	que.Encode = true
	que.EncodeFunc = bytes.ToUpper
	payloads := [][]byte{
		[]byte("hello"),
		[]byte("batch"),
	}

	var want []byte
	for _, payload := range payloads {
		want = append(want, que.BuildMessage(payload)...)
	}

	var buf bytes.Buffer
	if err := que.WriteFramesBuffers(&buf, payloads...); err != nil {
		t.Fatalf("WriteFramesBuffers failed: %v", err)
	}
	if got := buf.Bytes(); !bytes.Equal(got, want) {
		t.Fatalf("WriteFramesBuffers mismatch with EncodeFunc: got %v want %v", got, want)
	}
}

func TestQueueParseMessageSplitAcrossCalls(t *testing.T) {
	que := NewQueueWithCount(1)
	frame := que.BuildMessage([]byte("hello"))

	if err := que.ParseMessage(frame[:3], "split"); err != nil {
		t.Fatalf("unexpected error on partial magic: %v", err)
	}
	if err := que.ParseMessage(frame[3:11], "split"); err != nil {
		t.Fatalf("unexpected error on partial header: %v", err)
	}
	if err := que.ParseMessage(frame[11:], "split"); err != nil {
		t.Fatalf("unexpected error on payload completion: %v", err)
	}

	select {
	case data := <-que.RestoreChan():
		if data.ID != 0 {
			t.Fatalf("expected deprecated frame ID to stay zero, got %d", data.ID)
		}
		if data.Conn != "split" {
			t.Fatalf("unexpected conn: %#v", data.Conn)
		}
		if !bytes.Equal(data.Msg, []byte("hello")) {
			t.Fatalf("unexpected payload: %q", data.Msg)
		}
	case <-time.After(200 * time.Millisecond):
		t.Fatal("did not restore parsed frame")
	}
}

func TestQueueParseMessageViewSplitAcrossCalls(t *testing.T) {
	que := NewQueue()
	frame := que.BuildMessage([]byte("hello"))
	var got [][]byte

	handler := func(view FrameView) error {
		got = append(got, cloneBytes(view.Payload))
		if view.Conn != "split-view" {
			t.Fatalf("unexpected conn: %#v", view.Conn)
		}
		return nil
	}

	if err := que.ParseMessageView(frame[:3], "split-view", handler); err != nil {
		t.Fatalf("unexpected error on partial magic: %v", err)
	}
	if err := que.ParseMessageView(frame[3:11], "split-view", handler); err != nil {
		t.Fatalf("unexpected error on partial header: %v", err)
	}
	if err := que.ParseMessageView(frame[11:], "split-view", handler); err != nil {
		t.Fatalf("unexpected error on payload completion: %v", err)
	}

	if len(got) != 1 {
		t.Fatalf("unexpected frame count: got %d want 1", len(got))
	}
	if !bytes.Equal(got[0], []byte("hello")) {
		t.Fatalf("unexpected payload: %q", got[0])
	}
}

func TestQueueParseMessageOwnedSplitAcrossCalls(t *testing.T) {
	que := NewQueue()
	frame := que.BuildMessage([]byte("hello"))
	var got []MsgQueue

	handler := func(msg MsgQueue) error {
		got = append(got, MsgQueue{
			Msg:  cloneBytes(msg.Msg),
			Conn: msg.Conn,
		})
		return nil
	}

	if err := que.ParseMessageOwned(frame[:3], "split-owned", handler); err != nil {
		t.Fatalf("unexpected error on partial magic: %v", err)
	}
	if err := que.ParseMessageOwned(frame[3:11], "split-owned", handler); err != nil {
		t.Fatalf("unexpected error on partial header: %v", err)
	}
	if err := que.ParseMessageOwned(frame[11:], "split-owned", handler); err != nil {
		t.Fatalf("unexpected error on payload completion: %v", err)
	}

	if len(got) != 1 {
		t.Fatalf("unexpected frame count: got %d want 1", len(got))
	}
	if got[0].Conn != "split-owned" {
		t.Fatalf("unexpected conn: %#v", got[0].Conn)
	}
	if !bytes.Equal(got[0].Msg, []byte("hello")) {
		t.Fatalf("unexpected payload: %q", got[0].Msg)
	}
	select {
	case msg := <-que.RestoreChan():
		t.Fatalf("ParseMessageOwned should not use RestoreChan, got %#v", msg)
	default:
	}
}

func TestQueueParseMessageSkipsGarbagePrefix(t *testing.T) {
	que := NewQueueWithCount(1)
	frame := que.BuildMessage([]byte("hello"))

	err := que.ParseMessage(append([]byte("junk"), frame...), "garbage")
	if !errors.Is(err, ErrQueueDataFormat) {
		t.Fatalf("expected data format error, got %v", err)
	}

	select {
	case data := <-que.RestoreChan():
		if !bytes.Equal(data.Msg, []byte("hello")) {
			t.Fatalf("unexpected payload after resync: %q", data.Msg)
		}
	case <-time.After(200 * time.Millisecond):
		t.Fatal("did not restore frame after skipping garbage")
	}
}

func TestQueueParseMessageViewSkipsGarbagePrefix(t *testing.T) {
	que := NewQueue()
	frame := que.BuildMessage([]byte("hello"))
	var got []byte

	err := que.ParseMessageView(append([]byte("junk"), frame...), "garbage-view", func(view FrameView) error {
		got = cloneBytes(view.Payload)
		return nil
	})
	if !errors.Is(err, ErrQueueDataFormat) {
		t.Fatalf("expected data format error, got %v", err)
	}
	if !bytes.Equal(got, []byte("hello")) {
		t.Fatalf("unexpected payload after resync: %q", got)
	}
}

func TestQueueParseMessageViewNilHandler(t *testing.T) {
	que := NewQueue()
	err := que.ParseMessageView(que.BuildMessage([]byte("hello")), "nil-handler", nil)
	if !errors.Is(err, ErrQueueFrameHandlerNil) {
		t.Fatalf("ParseMessageView error = %v, want %v", err, ErrQueueFrameHandlerNil)
	}
}

func TestQueueParseMessageOwnedNilHandler(t *testing.T) {
	que := NewQueue()
	err := que.ParseMessageOwned(que.BuildMessage([]byte("hello")), "nil-handler-owned", nil)
	if !errors.Is(err, ErrQueueFrameHandlerNil) {
		t.Fatalf("ParseMessageOwned error = %v, want %v", err, ErrQueueFrameHandlerNil)
	}
}

func TestQueueWriteFrameNilWriter(t *testing.T) {
	que := NewQueue()
	err := que.WriteFrame(nil, []byte("hello"))
	if !errors.Is(err, io.ErrClosedPipe) {
		t.Fatalf("WriteFrame error = %v, want %v", err, io.ErrClosedPipe)
	}
}

func TestQueueWriteFrameBuffersNilWriter(t *testing.T) {
	que := NewQueue()
	err := que.WriteFrameBuffers(nil, []byte("hello"))
	if !errors.Is(err, io.ErrClosedPipe) {
		t.Fatalf("WriteFrameBuffers error = %v, want %v", err, io.ErrClosedPipe)
	}
}

func TestQueueWriteFramesBuffersNilWriter(t *testing.T) {
	que := NewQueue()
	err := que.WriteFramesBuffers(nil, []byte("hello"))
	if !errors.Is(err, io.ErrClosedPipe) {
		t.Fatalf("WriteFramesBuffers error = %v, want %v", err, io.ErrClosedPipe)
	}
}

func TestQueueParseMessageRejectsUnsupportedVersion(t *testing.T) {
	que := NewQueueWithCount(1)
	frame := que.BuildMessage([]byte("hello"))
	frame[12] = 2

	err := que.ParseMessage(frame, "version")
	if !errors.Is(err, ErrQueueUnsupportedVersion) {
		t.Fatalf("expected unsupported version error, got %v", err)
	}

	select {
	case data := <-que.RestoreChan():
		t.Fatalf("unexpected restored frame: %#v", data)
	default:
	}
}

func TestQueueParseMessageRejectsMessageTooLarge(t *testing.T) {
	que := NewQueueCtx(nil, 1, 4)
	frame := que.BuildMessage([]byte("hello"))

	err := que.ParseMessage(frame, "large")
	if !errors.Is(err, ErrQueueMessageTooLarge) {
		t.Fatalf("expected message too large error, got %v", err)
	}

	select {
	case data := <-que.RestoreChan():
		t.Fatalf("unexpected restored frame: %#v", data)
	default:
	}
}

func TestQueueParseMessageRejectsInvalidConnKey(t *testing.T) {
	que := NewQueue()
	frame := que.BuildMessage([]byte("hello"))
	err := que.ParseMessage(frame, []byte("not-comparable"))
	if !errors.Is(err, ErrQueueConnKeyInvalid) {
		t.Fatalf("expected invalid conn key error, got %v", err)
	}
}

func TestQueueParseMessageRejectsNilConnKey(t *testing.T) {
	que := NewQueue()
	frame := que.BuildMessage([]byte("hello"))
	err := que.ParseMessage(frame, nil)
	if !errors.Is(err, ErrQueueConnKeyNil) {
		t.Fatalf("expected nil conn key error, got %v", err)
	}
}

func TestQueuePayloadSizeToUint32RejectsOverflow(t *testing.T) {
	_, err := payloadSizeToUint32(uint64(^uint32(0)) + 1)
	if !errors.Is(err, ErrQueueMessageTooLarge) {
		t.Fatalf("expected message too large error, got %v", err)
	}
}

func TestQueueRestoreDurationZeroWaitsUntilMessage(t *testing.T) {
	que := NewQueueWithCount(1)
	que.RestoreDuration(0)

	type restoreResult struct {
		msg MsgQueue
		err error
	}
	resultCh := make(chan restoreResult, 1)
	go func() {
		msg, err := que.Restore()
		resultCh <- restoreResult{msg: msg, err: err}
	}()

	select {
	case result := <-resultCh:
		t.Fatalf("Restore returned too early: %#v", result)
	case <-time.After(50 * time.Millisecond):
	}

	if err := que.ParseMessage(que.BuildMessage([]byte("hello")), "forever"); err != nil {
		t.Fatalf("ParseMessage failed: %v", err)
	}

	select {
	case result := <-resultCh:
		if result.err != nil {
			t.Fatalf("Restore returned error: %v", result.err)
		}
		if result.msg.Conn != "forever" || !bytes.Equal(result.msg.Msg, []byte("hello")) {
			t.Fatalf("unexpected restore result: %#v", result.msg)
		}
	case <-time.After(200 * time.Millisecond):
		t.Fatal("Restore did not return after message arrival")
	}
}

func TestQueueRestoreReturnsContextErrorOnStop(t *testing.T) {
	que := NewQueue()
	resultCh := make(chan error, 1)
	go func() {
		_, err := que.Restore()
		resultCh <- err
	}()

	que.Stop()

	select {
	case err := <-resultCh:
		if !errors.Is(err, context.Canceled) {
			t.Fatalf("expected context.Canceled, got %v", err)
		}
	case <-time.After(200 * time.Millisecond):
		t.Fatal("Restore did not return after Stop")
	}
}

func TestQueueRestoreChanClosesOnStop(t *testing.T) {
	que := NewQueue()
	resultCh := make(chan bool, 1)
	go func() {
		_, ok := <-que.RestoreChan()
		resultCh <- ok
	}()

	que.Stop()

	select {
	case ok := <-resultCh:
		if ok {
			t.Fatal("expected RestoreChan to close after Stop")
		}
	case <-time.After(200 * time.Millisecond):
		t.Fatal("RestoreChan did not close after Stop")
	}
}

func TestQueueRestoreChanClosesOnContextCancel(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	que := NewQueueCtx(ctx, 1, 0)
	resultCh := make(chan bool, 1)
	go func() {
		_, ok := <-que.RestoreChan()
		resultCh <- ok
	}()

	cancel()

	select {
	case ok := <-resultCh:
		if ok {
			t.Fatal("expected RestoreChan to close after context cancel")
		}
	case <-time.After(200 * time.Millisecond):
		t.Fatal("RestoreChan did not close after context cancel")
	}
}

func TestQueueParseMessageReturnsContextErrorWhenStoppedWhilePoolIsFull(t *testing.T) {
	que := NewQueueWithCount(1)
	if err := que.ParseMessage(que.BuildMessage([]byte("first")), "full"); err != nil {
		t.Fatalf("ParseMessage first failed: %v", err)
	}

	errCh := make(chan error, 1)
	go func() {
		errCh <- que.ParseMessage(que.BuildMessage([]byte("second")), "full")
	}()

	select {
	case err := <-errCh:
		t.Fatalf("ParseMessage returned before Stop: %v", err)
	case <-time.After(50 * time.Millisecond):
	}

	que.Stop()

	select {
	case err := <-errCh:
		if !errors.Is(err, context.Canceled) {
			t.Fatalf("expected context.Canceled, got %v", err)
		}
	case <-time.After(200 * time.Millisecond):
		t.Fatal("ParseMessage did not return after Stop")
	}
}

func TestQueueParseMessageViewAllowsReentrantParseOnSameConn(t *testing.T) {
	que := NewQueue()
	reentered := false

	err := que.ParseMessageView(que.BuildMessage([]byte("outer")), "reentrant", func(view FrameView) error {
		if !bytes.Equal(view.Payload, []byte("outer")) {
			t.Fatalf("unexpected outer payload: %q", view.Payload)
		}
		return que.ParseMessageView(que.BuildMessage([]byte("inner")), "reentrant", func(inner FrameView) error {
			reentered = true
			if !bytes.Equal(inner.Payload, []byte("inner")) {
				t.Fatalf("unexpected inner payload: %q", inner.Payload)
			}
			return nil
		})
	})
	if err != nil {
		t.Fatalf("ParseMessageView failed: %v", err)
	}
	if !reentered {
		t.Fatal("expected reentrant ParseMessageView to run")
	}
}