Initial backend repository commit.

Set up project files and add .gitignore to exclude local build/runtime artifacts. Made-with: Cursor
2026-03-09 21:28:58 +08:00
commit 4d8f2ec997
102 changed files with 25022 additions and 0 deletions
--- a/internal/pkg/openai/client.go
+++ b/internal/pkg/openai/client.go
@@ -0,0 +1,438 @@
+package openai
+
+import (
+	"bytes"
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"image"
+	_ "image/gif"
+	"image/jpeg"
+	_ "image/png"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+
+	xdraw "golang.org/x/image/draw"
+)
+
+const moderationSystemPrompt = "你是中文社区的内容审核助手，负责对“帖子标题、正文、配图”做联合审核。目标是平衡社区安全与正常交流：必须拦截高风险违规内容，但不要误伤正常玩梗、二创、吐槽和轻度调侃。请只输出指定JSON。\n\n审核流程：\n1) 先判断是否命中硬性违规；\n2) 再判断语境（玩笑/自嘲/朋友间互动/作品讨论）；\n3) 做文图交叉判断（文本+图片合并理解）；\n4) 给出 approved 与简短 reason。\n\n硬性违规（命中任一项必须 approved=false）：\nA. 宣传对立与煽动撕裂：\n- 明确煽动群体对立、地域对立、性别对立、民族宗教对立，鼓动仇恨、排斥、报复。\nB. 严重人身攻击与网暴引导：\n- 持续性侮辱贬损、羞辱人格、号召围攻/骚扰/挂人/线下冲突。\nC. 开盒/人肉/隐私暴露：\n- 故意公开、拼接、索取他人可识别隐私信息（姓名+联系方式、身份证号、住址、学校单位、车牌、定位轨迹等）；\n- 图片/截图中出现可识别隐私信息并伴随曝光意图，也按违规处理。\nD. 其他高危违规：\n- 违法犯罪、暴力威胁、极端仇恨、色情低俗、诈骗引流、恶意广告等。\n\n放行规则（以下通常 approved=true）：\n- 正常玩梗、表情包、谐音梗、二次创作、无恶意的吐槽；\n- 非定向、轻度口语化吐槽（无明确攻击对象、无网暴号召、无隐私暴露）；\n- 对社会事件/作品的理性讨论、观点争论（即使语气尖锐，但未煽动对立或人身攻击）。\n\n边界判定：\n- 若只是“梗文化表达”且不指向现实伤害，优先通过；\n- 若存在明确伤害意图（煽动、围攻、曝光隐私），必须拒绝；\n- 对模糊内容不因个别粗口直接拒绝，需结合对象、意图、号召性和可执行性综合判断。\n\nreason 要求：\n- approved=false 时：中文10-30字，说明核心违规点；\n- approved=true 时：reason 为空字符串。\n\n输出格式（严格）：\n仅输出一行JSON对象，不要Markdown，不要额外解释：\n{\"approved\": true/false, \"reason\": \"...\"}"
+
+const (
+	defaultMaxImagesPerModerationRequest = 1
+	maxModerationResultRetries           = 3
+	maxChatCompletionRetries             = 3
+	initialRetryBackoff                  = 500 * time.Millisecond
+	maxDownloadImageBytes                = 10 * 1024 * 1024
+	maxModerationImageSide               = 1280
+	compressedJPEGQuality                = 72
+	maxCompressedPayloadBytes            = 1536 * 1024
+)
+
+type Client interface {
+	IsEnabled() bool
+	Config() Config
+	ModeratePost(ctx context.Context, title, content string, images []string) (bool, string, error)
+	ModerateComment(ctx context.Context, content string, images []string) (bool, string, error)
+}
+
+type clientImpl struct {
+	cfg        Config
+	httpClient *http.Client
+}
+
+func NewClient(cfg Config) Client {
+	timeout := cfg.RequestTimeoutSeconds
+	if timeout <= 0 {
+		timeout = 30
+	}
+	return &clientImpl{
+		cfg: cfg,
+		httpClient: &http.Client{
+			Timeout: time.Duration(timeout) * time.Second,
+		},
+	}
+}
+
+func (c *clientImpl) IsEnabled() bool {
+	return c.cfg.Enabled && c.cfg.APIKey != "" && c.cfg.BaseURL != ""
+}
+
+func (c *clientImpl) Config() Config {
+	return c.cfg
+}
+
+func (c *clientImpl) ModeratePost(ctx context.Context, title, content string, images []string) (bool, string, error) {
+	if !c.IsEnabled() {
+		return true, "", nil
+	}
+	return c.moderateContentInBatches(ctx, fmt.Sprintf("帖子标题：%s\n帖子内容：%s", title, content), images)
+}
+
+func (c *clientImpl) ModerateComment(ctx context.Context, content string, images []string) (bool, string, error) {
+	if !c.IsEnabled() {
+		return true, "", nil
+	}
+	return c.moderateContentInBatches(ctx, fmt.Sprintf("评论内容：%s", content), images)
+}
+
+func (c *clientImpl) moderateContentInBatches(ctx context.Context, contentPrompt string, images []string) (bool, string, error) {
+	cleanImages := normalizeImageURLs(images)
+	optimizedImages := c.optimizeImagesForModeration(ctx, cleanImages)
+	maxImagesPerRequest := c.maxImagesPerModerationRequest()
+	totalBatches := 1
+	if len(optimizedImages) > 0 {
+		totalBatches = (len(optimizedImages) + maxImagesPerRequest - 1) / maxImagesPerRequest
+	}
+
+	// 图片超过单批上限时分批审核，任一批次拒绝即整体拒绝
+	for i := 0; i < totalBatches; i++ {
+		start := i * maxImagesPerRequest
+		end := start + maxImagesPerRequest
+		if end > len(optimizedImages) {
+			end = len(optimizedImages)
+		}
+
+		batchImages := []string{}
+		if len(optimizedImages) > 0 {
+			batchImages = optimizedImages[start:end]
+		}
+
+		approved, reason, err := c.moderateSingleBatch(ctx, contentPrompt, batchImages, i+1, totalBatches)
+		if err != nil {
+			return false, "", err
+		}
+		if !approved {
+			if strings.TrimSpace(reason) != "" && totalBatches > 1 {
+				reason = fmt.Sprintf("第%d/%d批图片未通过：%s", i+1, totalBatches, reason)
+			}
+			return false, reason, nil
+		}
+	}
+
+	return true, "", nil
+}
+
+func (c *clientImpl) moderateSingleBatch(
+	ctx context.Context,
+	contentPrompt string,
+	images []string,
+	batchNo, totalBatches int,
+) (bool, string, error) {
+	userPrompt := fmt.Sprintf(
+		"%s\n图片批次：%d/%d（本次仅提供当前批次图片）",
+		contentPrompt,
+		batchNo,
+		totalBatches,
+	)
+
+	var lastErr error
+	for attempt := 0; attempt < maxModerationResultRetries; attempt++ {
+		replyText, err := c.chatCompletion(ctx, c.cfg.ModerationModel, moderationSystemPrompt, userPrompt, images, 0.1, 220)
+		if err != nil {
+			lastErr = err
+		} else {
+			parsed := struct {
+				Approved bool   `json:"approved"`
+				Reason   string `json:"reason"`
+			}{}
+			if err := json.Unmarshal([]byte(extractJSONObject(replyText)), &parsed); err != nil {
+				lastErr = fmt.Errorf("failed to parse moderation result: %w", err)
+			} else {
+				return parsed.Approved, parsed.Reason, nil
+			}
+		}
+
+		if attempt == maxModerationResultRetries-1 {
+			break
+		}
+		if sleepErr := sleepWithBackoff(ctx, attempt); sleepErr != nil {
+			return false, "", sleepErr
+		}
+	}
+
+	return false, "", fmt.Errorf(
+		"moderation batch %d/%d failed after %d attempts: %w",
+		batchNo,
+		totalBatches,
+		maxModerationResultRetries,
+		lastErr,
+	)
+}
+
+type chatCompletionsRequest struct {
+	Model       string        `json:"model"`
+	Messages    []chatMessage `json:"messages"`
+	Temperature float64       `json:"temperature,omitempty"`
+	MaxTokens   int           `json:"max_tokens,omitempty"`
+}
+
+type chatMessage struct {
+	Role    string      `json:"role"`
+	Content interface{} `json:"content"`
+}
+
+type contentPart struct {
+	Type     string        `json:"type"`
+	Text     string        `json:"text,omitempty"`
+	ImageURL *imageURLPart `json:"image_url,omitempty"`
+}
+
+type imageURLPart struct {
+	URL string `json:"url"`
+}
+
+type chatCompletionsResponse struct {
+	Choices []struct {
+		Message struct {
+			Content string `json:"content"`
+		} `json:"message"`
+	} `json:"choices"`
+}
+
+func (c *clientImpl) chatCompletion(
+	ctx context.Context,
+	model string,
+	systemPrompt string,
+	userPrompt string,
+	images []string,
+	temperature float64,
+	maxTokens int,
+) (string, error) {
+	if model == "" {
+		return "", fmt.Errorf("model is empty")
+	}
+
+	cleanImages := normalizeImageURLs(images)
+
+	userParts := []contentPart{
+		{Type: "text", Text: userPrompt},
+	}
+	for _, image := range cleanImages {
+		userParts = append(userParts, contentPart{
+			Type:     "image_url",
+			ImageURL: &imageURLPart{URL: image},
+		})
+	}
+
+	reqBody := chatCompletionsRequest{
+		Model: model,
+		Messages: []chatMessage{
+			{Role: "system", Content: systemPrompt},
+			{Role: "user", Content: userParts},
+		},
+		Temperature: temperature,
+		MaxTokens:   maxTokens,
+	}
+
+	data, err := json.Marshal(reqBody)
+	if err != nil {
+		return "", fmt.Errorf("marshal request: %w", err)
+	}
+
+	baseURL := strings.TrimRight(c.cfg.BaseURL, "/")
+	endpoint := baseURL + "/v1/chat/completions"
+	if strings.HasSuffix(baseURL, "/v1") {
+		endpoint = baseURL + "/chat/completions"
+	}
+
+	var lastErr error
+	for attempt := 0; attempt < maxChatCompletionRetries; attempt++ {
+		body, statusCode, err := c.doChatCompletionRequest(ctx, endpoint, data)
+		if err != nil {
+			lastErr = err
+		} else if statusCode >= 400 {
+			lastErr = fmt.Errorf("openai error status=%d body=%s", statusCode, string(body))
+			if !isRetryableStatusCode(statusCode) {
+				return "", lastErr
+			}
+		} else {
+			var parsed chatCompletionsResponse
+			if err := json.Unmarshal(body, &parsed); err != nil {
+				return "", fmt.Errorf("decode response: %w", err)
+			}
+			if len(parsed.Choices) == 0 {
+				return "", fmt.Errorf("empty response choices")
+			}
+			return parsed.Choices[0].Message.Content, nil
+		}
+
+		if attempt == maxChatCompletionRetries-1 {
+			break
+		}
+		if sleepErr := sleepWithBackoff(ctx, attempt); sleepErr != nil {
+			return "", sleepErr
+		}
+	}
+
+	return "", lastErr
+}
+
+func (c *clientImpl) doChatCompletionRequest(ctx context.Context, endpoint string, data []byte) ([]byte, int, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, endpoint, bytes.NewReader(data))
+	if err != nil {
+		return nil, 0, fmt.Errorf("create request: %w", err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Authorization", "Bearer "+c.cfg.APIKey)
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, 0, fmt.Errorf("request openai: %w", err)
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, 0, fmt.Errorf("read response: %w", err)
+	}
+	return body, resp.StatusCode, nil
+}
+
+func isRetryableStatusCode(statusCode int) bool {
+	if statusCode == http.StatusTooManyRequests {
+		return true
+	}
+	return statusCode >= 500 && statusCode <= 599
+}
+
+func sleepWithBackoff(ctx context.Context, attempt int) error {
+	delay := initialRetryBackoff * time.Duration(1<<attempt)
+	timer := time.NewTimer(delay)
+	defer timer.Stop()
+
+	select {
+	case <-ctx.Done():
+		return fmt.Errorf("request cancelled: %w", ctx.Err())
+	case <-timer.C:
+		return nil
+	}
+}
+
+func normalizeImageURLs(images []string) []string {
+	clean := make([]string, 0, len(images))
+	for _, image := range images {
+		trimmed := strings.TrimSpace(image)
+		if trimmed == "" {
+			continue
+		}
+		clean = append(clean, trimmed)
+	}
+	return clean
+}
+
+func extractJSONObject(raw string) string {
+	text := strings.TrimSpace(raw)
+	start := strings.Index(text, "{")
+	end := strings.LastIndex(text, "}")
+	if start >= 0 && end > start {
+		return text[start : end+1]
+	}
+	return text
+}
+
+func (c *clientImpl) maxImagesPerModerationRequest() int {
+	// 审核固定单图请求，降低单次payload体积，减少超时风险。
+	if c.cfg.ModerationMaxImagesPerRequest <= 0 {
+		return defaultMaxImagesPerModerationRequest
+	}
+	if c.cfg.ModerationMaxImagesPerRequest > 1 {
+		return 1
+	}
+	return c.cfg.ModerationMaxImagesPerRequest
+}
+
+func (c *clientImpl) optimizeImagesForModeration(ctx context.Context, images []string) []string {
+	if len(images) == 0 {
+		return images
+	}
+
+	optimized := make([]string, 0, len(images))
+	for _, imageURL := range images {
+		optimized = append(optimized, c.tryCompressImageForModeration(ctx, imageURL))
+	}
+	return optimized
+}
+
+func (c *clientImpl) tryCompressImageForModeration(ctx context.Context, imageURL string) string {
+	parsed, err := url.Parse(imageURL)
+	if err != nil || (parsed.Scheme != "http" && parsed.Scheme != "https") {
+		return imageURL
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, imageURL, nil)
+	if err != nil {
+		return imageURL
+	}
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return imageURL
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode >= 400 {
+		return imageURL
+	}
+	if !strings.HasPrefix(strings.ToLower(resp.Header.Get("Content-Type")), "image/") {
+		return imageURL
+	}
+
+	originBytes, err := io.ReadAll(io.LimitReader(resp.Body, maxDownloadImageBytes))
+	if err != nil || len(originBytes) == 0 {
+		return imageURL
+	}
+
+	srcImg, _, err := image.Decode(bytes.NewReader(originBytes))
+	if err != nil {
+		return imageURL
+	}
+
+	dstImg := resizeIfNeeded(srcImg, maxModerationImageSide)
+	var buf bytes.Buffer
+	if err := jpeg.Encode(&buf, dstImg, &jpeg.Options{Quality: compressedJPEGQuality}); err != nil {
+		return imageURL
+	}
+
+	compressed := buf.Bytes()
+	if len(compressed) == 0 || len(compressed) > maxCompressedPayloadBytes {
+		return imageURL
+	}
+	// 压缩效果不明显时直接使用原图URL，避免增大请求体。
+	if len(compressed) >= int(float64(len(originBytes))*0.95) {
+		return imageURL
+	}
+
+	return "data:image/jpeg;base64," + base64.StdEncoding.EncodeToString(compressed)
+}
+
+func resizeIfNeeded(src image.Image, maxSide int) image.Image {
+	bounds := src.Bounds()
+	w := bounds.Dx()
+	h := bounds.Dy()
+	if w <= 0 || h <= 0 || max(w, h) <= maxSide {
+		return src
+	}
+
+	newW, newH := w, h
+	if w >= h {
+		newW = maxSide
+		newH = int(float64(h) * (float64(maxSide) / float64(w)))
+	} else {
+		newH = maxSide
+		newW = int(float64(w) * (float64(maxSide) / float64(h)))
+	}
+	if newW < 1 {
+		newW = 1
+	}
+	if newH < 1 {
+		newH = 1
+	}
+
+	dst := image.NewRGBA(image.Rect(0, 0, newW, newH))
+	xdraw.CatmullRom.Scale(dst, dst.Bounds(), src, bounds, xdraw.Over, nil)
+	return dst
+}