package vision

import (
	"context"
	"encoding/json"
	"errors"
	"io"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"

	"git.yeij.top/AskaEth/Cyrene_v2/internal/config"
)

func TestOpenAICompatibleAdapter_Describe(t *testing.T) {
	t.Parallel()
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path != "/chat/completions" {
			t.Errorf("path = %s, want /chat/completions", r.URL.Path)
		}
		var body map[string]any
		if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
			t.Fatalf("decode body: %v", err)
		}
		msgs, _ := body["messages"].([]any)
		if len(msgs) != 1 {
			t.Fatalf("messages = %d, want 1", len(msgs))
		}
		content, _ := msgs[0].(map[string]any)["content"].([]any)
		if len(content) != 2 {
			t.Fatalf("content parts = %d, want 2", len(content))
		}
		w.Header().Set("Content-Type", "application/json")
		_, _ = io.WriteString(w, `{"choices":[{"message":{"content":"a red car"}}]}`)
	}))
	defer srv.Close()

	ad := NewOpenAICompatible(config.LLMConfig{BaseURL: srv.URL, Model: "vision-"})
	text, err := ad.Describe(context.Background(), ImageRef{Source: SourceBase64, Data: "aGVsbG8="}, "")
	if err != nil {
		t.Fatalf("Describe error: %v", err)
	}
	if text != "a red car" {
		t.Errorf("text = %q, want a red car", text)
	}
}

func TestOpenAICompatibleAdapter_NotConfigured(t *testing.T) {
	t.Parallel()
	ad := NewOpenAICompatible(config.LLMConfig{})
	if _, err := ad.Describe(context.Background(), ImageRef{Source: SourceBase64, Data: "aGVsbG8="}, ""); err == nil {
		t.Fatal("want error for empty base url, got nil")
	}
}

// stubTransport 让测试不经网络直接给出响应。
type stubTransport func(*http.Request) (*http.Response, error)

func (f stubTransport) RoundTrip(r *http.Request) (*http.Response, error) { return f(r) }

// countingBody 记录被读走的字节数，用来断言错误路径**有界读**。
type countingBody struct {
	r io.Reader
	n *int64
}

func (b *countingBody) Read(p []byte) (int, error) {
	n, err := b.r.Read(p)
	*b.n += int64(n)
	return n, err
}

func (b *countingBody) Close() error { return nil }

// TestOpenAICompatibleAdapter_ErrorBodyKeptOutOfError 覆盖 M41 的视觉一处：
// 旧实现沿用取图上限（50 MiB）读错误体，再把它拼进 error —— 既是日志面
// （整个 50 MiB 的错误体都能进去），也是 DoS 面（一次超大错误响应就吃掉内存）。
//
// 两个断言各能单独打红：① 正文出现在 error 里 ⇒ 又回到「拼原文」；
// ② 错误路径读走超过 maxErrorBodyBytes ⇒ 又回到按取图上限整段读。
// 测试体用 8 MiB（远大于 4 KiB、远小于 50 MiB）：足以证伪无界读，又不必在
// 测试里分配 50 MiB。
func TestOpenAICompatibleAdapter_ErrorBodyKeptOutOfError(t *testing.T) {
	t.Parallel()
	const sentinel = "SENTINEL-VISION-ERROR-BODY-7d2a"
	var read int64
	payload := sentinel + strings.Repeat("x", 8<<20)
	ad := newAdapter("https://vision.example.com")
	ad.client = &http.Client{Transport: stubTransport(func(*http.Request) (*http.Response, error) {
		return &http.Response{
			StatusCode: http.StatusInternalServerError,
			Header:     http.Header{"Content-Type": []string{"application/json"}},
			Body:       &countingBody{r: strings.NewReader(payload), n: &read},
		}, nil
	})}

	_, err := ad.Describe(context.Background(), ImageRef{Source: SourceBase64, Data: "aGVsbG8="}, "")
	if err == nil {
		t.Fatal("want error, got nil")
	}
	if !errors.Is(err, ErrUpstream) {
		t.Fatalf("err = %v, want ErrUpstream", err)
	}
	if strings.Contains(err.Error(), sentinel) {
		t.Errorf("error text carries the response body: %v", err)
	}
	if read > maxErrorBodyBytes {
		t.Errorf("error path read %d bytes of the error body, want <= %d", read, maxErrorBodyBytes)
	}
	if !strings.Contains(err.Error(), "500") {
		t.Errorf("err = %v, want the status kept for triage", err)
	}
}