package openai

import (
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"

	"github.com/gin-gonic/gin"
	"github.com/router-for-me/CLIProxyAPI/v6/internal/interfaces"
	"github.com/router-for-me/CLIProxyAPI/v6/sdk/api/handlers"
	sdkconfig "github.com/router-for-me/CLIProxyAPI/v6/sdk/config"
)

func newResponsesStreamTestHandler(t *testing.T) (*OpenAIResponsesAPIHandler, *httptest.ResponseRecorder, *gin.Context, http.Flusher) {
	t.Helper()

	gin.SetMode(gin.TestMode)
	base := handlers.NewBaseAPIHandlers(&sdkconfig.SDKConfig{}, nil)
	h := NewOpenAIResponsesAPIHandler(base)

	recorder := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(recorder)
	c.Request = httptest.NewRequest(http.MethodPost, "/v1/responses", nil)

	flusher, ok := c.Writer.(http.Flusher)
	if !ok {
		t.Fatalf("expected gin writer to implement http.Flusher")
	}

	return h, recorder, c, flusher
}

func TestForwardResponsesStreamSeparatesDataOnlySSEChunks(t *testing.T) {
	h, recorder, c, flusher := newResponsesStreamTestHandler(t)

	data := make(chan []byte, 2)
	errs := make(chan *interfaces.ErrorMessage)
	data <- []byte("data: {\"type\":\"response.output_item.done\",\"item\":{\"type\":\"function_call\",\"arguments\":\"{}\"}}")
	data <- []byte("data: {\"type\":\"response.completed\",\"response\":{\"id\":\"resp-1\",\"output\":[]}}")
	close(data)
	close(errs)

	h.forwardResponsesStream(c, flusher, func(error) {}, data, errs, nil)
	body := recorder.Body.String()
	parts := strings.Split(strings.TrimSpace(body), "\n\n")
	if len(parts) != 2 {
		t.Fatalf("expected 2 SSE events, got %d. Body: %q", len(parts), body)
	}

	expectedPart1 := "data: {\"type\":\"response.output_item.done\",\"item\":{\"type\":\"function_call\",\"arguments\":\"{}\"}}"
	if parts[0] != expectedPart1 {
		t.Errorf("unexpected first event.\nGot: %q\nWant: %q", parts[0], expectedPart1)
	}

	expectedPart2 := "data: {\"type\":\"response.completed\",\"response\":{\"id\":\"resp-1\",\"output\":[]}}"
	if parts[1] != expectedPart2 {
		t.Errorf("unexpected second event.\nGot: %q\nWant: %q", parts[1], expectedPart2)
	}
}

func TestForwardResponsesStreamReassemblesSplitSSEEventChunks(t *testing.T) {
	h, recorder, c, flusher := newResponsesStreamTestHandler(t)

	data := make(chan []byte, 3)
	errs := make(chan *interfaces.ErrorMessage)
	data <- []byte("event: response.created")
	data <- []byte("data: {\"type\":\"response.created\",\"response\":{\"id\":\"resp-1\"}}")
	data <- []byte("\n")
	close(data)
	close(errs)

	h.forwardResponsesStream(c, flusher, func(error) {}, data, errs, nil)

	got := strings.TrimSuffix(recorder.Body.String(), "\n")
	want := "event: response.created\ndata: {\"type\":\"response.created\",\"response\":{\"id\":\"resp-1\"}}\n\n"
	if got != want {
		t.Fatalf("unexpected split-event framing.\nGot:  %q\nWant: %q", got, want)
	}
}

func TestForwardResponsesStreamPreservesValidFullSSEEventChunks(t *testing.T) {
	h, recorder, c, flusher := newResponsesStreamTestHandler(t)

	data := make(chan []byte, 1)
	errs := make(chan *interfaces.ErrorMessage)
	chunk := []byte("event: response.created\ndata: {\"type\":\"response.created\",\"response\":{\"id\":\"resp-1\"}}\n\n")
	data <- chunk
	close(data)
	close(errs)

	h.forwardResponsesStream(c, flusher, func(error) {}, data, errs, nil)

	got := strings.TrimSuffix(recorder.Body.String(), "\n")
	if got != string(chunk) {
		t.Fatalf("unexpected full-event framing.\nGot:  %q\nWant: %q", got, string(chunk))
	}
}

func TestForwardResponsesStreamBuffersSplitDataPayloadChunks(t *testing.T) {
	h, recorder, c, flusher := newResponsesStreamTestHandler(t)

	data := make(chan []byte, 2)
	errs := make(chan *interfaces.ErrorMessage)
	data <- []byte("data: {\"type\":\"response.created\"")
	data <- []byte(",\"response\":{\"id\":\"resp-1\"}}")
	close(data)
	close(errs)

	h.forwardResponsesStream(c, flusher, func(error) {}, data, errs, nil)

	got := recorder.Body.String()
	want := "data: {\"type\":\"response.created\",\"response\":{\"id\":\"resp-1\"}}\n\n\n"
	if got != want {
		t.Fatalf("unexpected split-data framing.\nGot:  %q\nWant: %q", got, want)
	}
}

func TestResponsesSSENeedsLineBreakSkipsChunksThatAlreadyStartWithNewline(t *testing.T) {
	if responsesSSENeedsLineBreak([]byte("event: response.created"), []byte("\n")) {
		t.Fatal("expected no injected newline before newline-only chunk")
	}
	if responsesSSENeedsLineBreak([]byte("event: response.created"), []byte("\r\n")) {
		t.Fatal("expected no injected newline before CRLF chunk")
	}
}

func TestForwardResponsesStreamDropsIncompleteTrailingDataChunkOnFlush(t *testing.T) {
	h, recorder, c, flusher := newResponsesStreamTestHandler(t)

	data := make(chan []byte, 1)
	errs := make(chan *interfaces.ErrorMessage)
	data <- []byte("data: {\"type\":\"response.created\"")
	close(data)
	close(errs)

	h.forwardResponsesStream(c, flusher, func(error) {}, data, errs, nil)

	if got := recorder.Body.String(); got != "\n" {
		t.Fatalf("expected incomplete trailing data to be dropped on flush.\nGot: %q", got)
	}
}