package openai_compat

import (
	"bytes"
	"context"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"time"

	"go.uber.org/zap"

	"iop/apps/node/internal/runtime"
	"iop/packages/go/config"
)

func TestOpenAICompatTunnelProvider(t *testing.T) {
	expectedBody := "data: {\"choices\":[{\"delta\":{\"reasoning_content\":\"think Qwen\"}}]}\n\ndata: [DONE]\n\n"

	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			t.Errorf("expected POST method, got %s", r.Method)
		}
		if r.URL.Path != "/v1/chat/completions" {
			t.Errorf("expected path /v1/chat/completions, got %s", r.URL.Path)
		}
		if r.Header.Get("Authorization") != "Bearer test-key" {
			t.Errorf("expected Authorization header, got %s", r.Header.Get("Authorization"))
		}

		w.Header().Set("Content-Type", "text/event-stream")
		w.Header().Set("X-Custom-Header", "custom-value")
		w.WriteHeader(http.StatusOK)
		_, _ = w.Write([]byte(expectedBody))
	}))
	defer server.Close()

	adapter := New(config.OpenAICompatConf{
		Endpoint: server.URL,
	}, zap.NewNop())

	sink := &fakeTunnelSink{}
	req := runtime.ProviderTunnelRequest{
		RunID:    "run-1",
		TunnelID: "tunnel-1",
		Method:   "POST",
		Path:     "/v1/chat/completions",
		Headers:  map[string]string{"Authorization": "Bearer test-key"},
		Body:     []byte(`{"model":"qwen3.6:35b","prompt":"hi"}`),
	}

	err := adapter.TunnelProvider(context.Background(), req, sink)
	if err != nil {
		t.Fatalf("TunnelProvider failed: %v", err)
	}

	frames := sink.all()
	if len(frames) < 3 {
		t.Fatalf("expected at least 3 frames, got %d", len(frames))
	}

	startFrame := frames[0]
	if startFrame.Kind != runtime.ProviderTunnelFrameKindResponseStart {
		t.Errorf("expected RESPONSE_START, got %s", startFrame.Kind)
	}
	if startFrame.StatusCode != http.StatusOK {
		t.Errorf("expected 200 OK, got %d", startFrame.StatusCode)
	}
	if startFrame.Headers["X-Custom-Header"] != "custom-value" {
		t.Errorf("expected Custom Header, got %v", startFrame.Headers)
	}

	var bodyBuffer bytes.Buffer
	var lastSeq int64 = 0
	for _, f := range frames[1 : len(frames)-1] {
		if f.Kind != runtime.ProviderTunnelFrameKindBody {
			t.Errorf("expected BODY kind, got %s", f.Kind)
		}
		if f.Sequence != lastSeq+1 {
			t.Errorf("expected seq %d, got %d", lastSeq+1, f.Sequence)
		}
		bodyBuffer.Write(f.Body)
		lastSeq = f.Sequence
	}
	if bodyBuffer.String() != expectedBody {
		t.Errorf("body mismatch: got %q, want %q", bodyBuffer.String(), expectedBody)
	}

	endFrame := frames[len(frames)-1]
	if endFrame.Kind != runtime.ProviderTunnelFrameKindEnd {
		t.Errorf("expected END, got %s", endFrame.Kind)
	}
	if !endFrame.End {
		t.Errorf("expected End true, got %v", endFrame.End)
	}
	if endFrame.Sequence != lastSeq+1 {
		t.Errorf("expected seq %d, got %d", lastSeq+1, endFrame.Sequence)
	}
	assertOrderedTunnelFrames(t, frames)
}

func TestOpenAICompatTunnelProvider_RelaysProviderHTTPError(t *testing.T) {
	expectedBody := `{"error":{"message":"unsupported field","type":"invalid_request_error","param":"custom_provider_options"}}`

	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			t.Errorf("expected POST method, got %s", r.Method)
		}
		if r.URL.Path != "/v1/chat/completions" {
			t.Errorf("expected path /v1/chat/completions, got %s", r.URL.Path)
		}

		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusUnprocessableEntity)
		_, _ = w.Write([]byte(expectedBody))
	}))
	defer server.Close()

	adapter := New(config.OpenAICompatConf{
		Endpoint: server.URL,
	}, zap.NewNop())

	sink := &fakeTunnelSink{}
	req := runtime.ProviderTunnelRequest{
		RunID:    "run-1",
		TunnelID: "tunnel-1",
		Method:   "POST",
		Path:     "/v1/chat/completions",
		Body:     []byte(`{"model":"qwen3.6:35b","custom_provider_options":{"reject":true}}`),
	}

	err := adapter.TunnelProvider(context.Background(), req, sink)
	if err != nil {
		t.Fatalf("TunnelProvider must relay provider HTTP errors as response frames, got error: %v", err)
	}

	frames := sink.all()
	if len(frames) < 3 {
		t.Fatalf("expected at least 3 frames, got %d", len(frames))
	}
	if frames[0].Kind != runtime.ProviderTunnelFrameKindResponseStart {
		t.Fatalf("expected RESPONSE_START, got %s", frames[0].Kind)
	}
	if frames[0].StatusCode != http.StatusUnprocessableEntity {
		t.Fatalf("expected provider status 422, got %d", frames[0].StatusCode)
	}
	if got := frames[0].Headers["Content-Type"]; got != "application/json" {
		t.Fatalf("expected provider Content-Type header, got %q", got)
	}
	var bodyBuffer bytes.Buffer
	for _, f := range frames[1 : len(frames)-1] {
		if f.Kind != runtime.ProviderTunnelFrameKindBody {
			t.Errorf("expected BODY kind, got %s", f.Kind)
		}
		bodyBuffer.Write(f.Body)
	}
	if bodyBuffer.String() != expectedBody {
		t.Fatalf("provider error body mismatch:\n got: %q\nwant: %q", bodyBuffer.String(), expectedBody)
	}
	if frames[len(frames)-1].Kind != runtime.ProviderTunnelFrameKindEnd {
		t.Fatalf("expected END, got %s", frames[len(frames)-1].Kind)
	}
	assertOrderedTunnelFrames(t, frames)
}

func TestOpenAICompatTunnelProvider_ResponsesPath(t *testing.T) {
	requestBody := `{"model":"served-model","input":"hi","max_output_tokens":123,"store":false}`
	expectedBody := "data: {\"type\":\"response.output_text.delta\",\"delta\":\"hi\"}\n\ndata: [DONE]\n\n"

	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			t.Errorf("expected POST method, got %s", r.Method)
		}
		if r.URL.Path != "/v1/responses" {
			t.Errorf("expected path /v1/responses, got %s", r.URL.Path)
		}
		if r.Header.Get("Authorization") != "Bearer test-key" {
			t.Errorf("expected Authorization header, got %s", r.Header.Get("Authorization"))
		}
		var got bytes.Buffer
		if _, err := got.ReadFrom(r.Body); err != nil {
			t.Fatalf("read request body: %v", err)
		}
		if got.String() != requestBody {
			t.Errorf("request body mismatch: got %q want %q", got.String(), requestBody)
		}

		w.Header().Set("Content-Type", "text/event-stream")
		w.WriteHeader(http.StatusOK)
		_, _ = w.Write([]byte(expectedBody))
	}))
	defer server.Close()

	adapter := New(config.OpenAICompatConf{
		Endpoint: server.URL,
	}, zap.NewNop())

	sink := &fakeTunnelSink{}
	req := runtime.ProviderTunnelRequest{
		RunID:    "run-1",
		TunnelID: "tunnel-1",
		Method:   "POST",
		Path:     "/v1/responses",
		Headers:  map[string]string{"Authorization": "Bearer test-key"},
		Body:     []byte(requestBody),
		Stream:   true,
	}

	err := adapter.TunnelProvider(context.Background(), req, sink)
	if err != nil {
		t.Fatalf("TunnelProvider failed: %v", err)
	}

	frames := sink.all()
	if len(frames) < 3 {
		t.Fatalf("expected at least 3 frames, got %d", len(frames))
	}
	if frames[0].Kind != runtime.ProviderTunnelFrameKindResponseStart {
		t.Errorf("expected RESPONSE_START, got %s", frames[0].Kind)
	}
	if frames[0].StatusCode != http.StatusOK {
		t.Errorf("expected 200 OK, got %d", frames[0].StatusCode)
	}
	var bodyBuffer bytes.Buffer
	for _, f := range frames[1 : len(frames)-1] {
		if f.Kind != runtime.ProviderTunnelFrameKindBody {
			t.Errorf("expected BODY kind, got %s", f.Kind)
		}
		bodyBuffer.Write(f.Body)
	}
	if bodyBuffer.String() != expectedBody {
		t.Errorf("body mismatch: got %q, want %q", bodyBuffer.String(), expectedBody)
	}
	if frames[len(frames)-1].Kind != runtime.ProviderTunnelFrameKindEnd {
		t.Errorf("expected END, got %s", frames[len(frames)-1].Kind)
	}
	assertOrderedTunnelFrames(t, frames)
}

func TestOpenAICompatTunnelProvider_Cancel(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	handlerObservedCancel := make(chan struct{})

	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "text/event-stream")
		w.WriteHeader(http.StatusOK)

		flusher, ok := w.(http.Flusher)
		for {
			_, err := w.Write([]byte("data: chunk\n\n"))
			if err != nil {
				close(handlerObservedCancel)
				return
			}
			if ok {
				flusher.Flush()
			}
			select {
			case <-r.Context().Done():
				close(handlerObservedCancel)
				return
			case <-time.After(10 * time.Millisecond):
			}
		}
	}))
	defer server.Close()

	adapter := New(config.OpenAICompatConf{
		Endpoint: server.URL,
	}, zap.NewNop())

	sink := &fakeTunnelSink{}
	req := runtime.ProviderTunnelRequest{
		RunID:    "run-1",
		TunnelID: "tunnel-1",
		Method:   "POST",
		Path:     "/v1/chat/completions",
		Body:     []byte(`{"prompt":"hi"}`),
	}

	errCh := make(chan error, 1)
	go func() {
		errCh <- adapter.TunnelProvider(ctx, req, sink)
	}()

	time.Sleep(100 * time.Millisecond)
	cancel()

	select {
	case err := <-errCh:
		if err == nil {
			t.Error("expected error from TunnelProvider on cancellation, got nil")
		}
	case <-time.After(2 * time.Second):
		t.Fatal("timeout waiting for TunnelProvider to return")
	}

	select {
	case <-handlerObservedCancel:
	case <-time.After(2 * time.Second):
		t.Fatal("handler did not observe context cancel")
	}

	frames := sink.all()
	if len(frames) < 2 {
		t.Fatalf("expected at least 2 frames, got %d: %+v", len(frames), frames)
	}
	assertOrderedTunnelFrames(t, frames)

	if frames[0].Kind != runtime.ProviderTunnelFrameKindResponseStart {
		t.Errorf("expected first frame RESPONSE_START, got %s", frames[0].Kind)
	}
	for i, f := range frames[1 : len(frames)-1] {
		if f.Kind != runtime.ProviderTunnelFrameKindBody {
			t.Errorf("mid frame %d: expected BODY before the terminal ERROR, got %s", i+1, f.Kind)
		}
	}
	lastFrame := frames[len(frames)-1]
	if lastFrame.Kind != runtime.ProviderTunnelFrameKindError {
		t.Errorf("expected last frame to be ERROR, got %s", lastFrame.Kind)
	}
	if lastFrame.Error == "" {
		t.Error("expected non-empty error message in frame")
	}
	if !strings.Contains(lastFrame.Error, "context canceled") {
		t.Errorf("expected cancellation error in terminal frame, got %q", lastFrame.Error)
	}
}

func TestOpenAICompatTunnelProvider_BodyReadError(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		hj, ok := w.(http.Hijacker)
		if !ok {
			t.Fatal("webserver doesn't support hijacking")
		}
		conn, _, err := hj.Hijack()
		if err != nil {
			t.Fatalf("hijack failed: %v", err)
		}
		defer conn.Close()

		_, _ = conn.Write([]byte("HTTP/1.1 200 OK\r\nContent-Type: text/event-stream\r\nContent-Length: 100\r\n\r\n"))
		_, _ = conn.Write([]byte("data: chunk1\n\n"))
	}))
	defer server.Close()

	adapter := New(config.OpenAICompatConf{
		Endpoint: server.URL,
	}, zap.NewNop())

	sink := &fakeTunnelSink{}
	req := runtime.ProviderTunnelRequest{
		RunID:    "run-1",
		TunnelID: "tunnel-1",
		Method:   "POST",
		Path:     "/v1/chat/completions",
		Body:     []byte(`{"prompt":"hi"}`),
	}

	err := adapter.TunnelProvider(context.Background(), req, sink)
	if err == nil {
		t.Fatal("expected error from body read failure, got nil")
	}

	frames := sink.all()
	if len(frames) < 2 {
		t.Fatalf("expected at least 2 frames, got %d: %+v", len(frames), frames)
	}
	assertOrderedTunnelFrames(t, frames)

	lastFrame := frames[len(frames)-1]
	if lastFrame.Kind != runtime.ProviderTunnelFrameKindError {
		t.Errorf("expected last frame to be ERROR, got %s", lastFrame.Kind)
	}
	if !strings.Contains(lastFrame.Error, "read response body") && !strings.Contains(lastFrame.Error, "EOF") {
		t.Errorf("expected body read error msg, got %q", lastFrame.Error)
	}
}

// TestOpenAICompatTunnelProvider_SinkWriteFailureStopsUpstreamRelay covers the
// Edge-write-failure leg of S09: when EmitTunnelFrame fails mid-stream the
// adapter stops relaying immediately, returns the emit error without appending
// further frames, and the upstream provider request is torn down.
func TestOpenAICompatTunnelProvider_SinkWriteFailureStopsUpstreamRelay(t *testing.T) {
	handlerObservedTeardown := make(chan struct{})

	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "text/event-stream")
		w.WriteHeader(http.StatusOK)

		flusher, ok := w.(http.Flusher)
		for {
			_, err := w.Write([]byte("data: chunk\n\n"))
			if err != nil {
				close(handlerObservedTeardown)
				return
			}
			if ok {
				flusher.Flush()
			}
			select {
			case <-r.Context().Done():
				close(handlerObservedTeardown)
				return
			case <-time.After(10 * time.Millisecond):
			}
		}
	}))
	defer server.Close()

	adapter := New(config.OpenAICompatConf{
		Endpoint: server.URL,
	}, zap.NewNop())

	// RESPONSE_START and the first BODY frame succeed; the next emit fails as
	// if the Edge socket write broke after the caller went away.
	sink := &failingTunnelSink{failAfter: 2}
	req := runtime.ProviderTunnelRequest{
		RunID:    "run-1",
		TunnelID: "tunnel-1",
		Method:   "POST",
		Path:     "/v1/chat/completions",
		Body:     []byte(`{"prompt":"hi"}`),
	}

	errCh := make(chan error, 1)
	go func() {
		errCh <- adapter.TunnelProvider(context.Background(), req, sink)
	}()

	var tunnelErr error
	select {
	case tunnelErr = <-errCh:
	case <-time.After(2 * time.Second):
		t.Fatal("timeout waiting for TunnelProvider to return after sink write failure")
	}
	if tunnelErr == nil || !strings.Contains(tunnelErr.Error(), "edge socket write failed") {
		t.Fatalf("expected the sink emit error to propagate, got %v", tunnelErr)
	}

	select {
	case <-handlerObservedTeardown:
	case <-time.After(2 * time.Second):
		t.Fatal("provider handler did not observe upstream request teardown")
	}

	frames := sink.all()
	if len(frames) != 2 {
		t.Fatalf("expected relay to stop at 2 frames after emit failure, got %d: %+v", len(frames), frames)
	}
	if frames[0].Kind != runtime.ProviderTunnelFrameKindResponseStart {
		t.Errorf("expected first frame RESPONSE_START, got %s", frames[0].Kind)
	}
	if frames[1].Kind != runtime.ProviderTunnelFrameKindBody {
		t.Errorf("expected second frame BODY, got %s", frames[1].Kind)
	}
	for i, f := range frames {
		if f.Sequence != int64(i) {
			t.Errorf("frame %d: sequence %d, want %d", i, f.Sequence, i)
		}
	}
}