package handler

import (
	"bytes"
	"fmt"
	"io"
	"net/http"
	"path"
	"strings"

	"github.com/gin-gonic/gin"
	"kefu-cloud/server/internal/config"
	"kefu-cloud/server/internal/media"
	"kefu-cloud/server/internal/middleware"
	"kefu-cloud/server/internal/storage"
)

type UploadHandler struct {
	store  storage.ObjectStorage
	cfg    config.StorageConfig
}

func NewUploadHandler(store storage.ObjectStorage, cfg config.StorageConfig) *UploadHandler {
	return &UploadHandler{store: store, cfg: cfg}
}

// UploadImage 客服端上传：multipart file → 处理 → 存对象存储
func (h *UploadHandler) UploadImage(c *gin.Context) {
	h.handleUpload(c, fmt.Sprintf("tenants/%d/chat", middleware.GetTenantID(c)))
}

// WidgetUploadImage 访客端上传：需 visitor token + session_id
func (h *UploadHandler) WidgetUploadImage(c *gin.Context) {
	sessionID := c.PostForm("session_id")
	if sessionID == "" {
		sessionID = c.Query("session_id")
	}
	if sessionID == "" {
		c.JSON(http.StatusBadRequest, gin.H{"code": 400, "message": "缺少 session_id"})
		return
	}
	token := visitorTokenFromRequest(c, c.PostForm("visitor_token"))
	var sid uint
	if _, err := fmt.Sscanf(sessionID, "%d", &sid); err != nil || sid == 0 {
		c.JSON(http.StatusBadRequest, gin.H{"code": 400, "message": "会话参数错误"})
		return
	}
	session, ok := loadVisitorSession(c, sid, token)
	if !ok {
		return
	}
	if session.Status == "ended" || session.Status == "archived" {
		c.JSON(http.StatusConflict, gin.H{"code": 409, "message": "会话已结束"})
		return
	}
	h.handleUpload(c, fmt.Sprintf("tenants/%d/widget/%d", session.TenantID, session.ID))
}

func (h *UploadHandler) handleUpload(c *gin.Context, keyPrefix string) {
	if h.store == nil {
		c.JSON(http.StatusServiceUnavailable, gin.H{"code": 503, "message": "对象存储未配置"})
		return
	}

	maxBytes := int64(h.cfg.MaxUploadMB) * 1024 * 1024
	if maxBytes <= 0 {
		maxBytes = 10 * 1024 * 1024
	}
	c.Request.Body = http.MaxBytesReader(c.Writer, c.Request.Body, maxBytes+512)
	file, header, err := c.Request.FormFile("file")
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"code": 400, "message": "请上传文件字段 file"})
		return
	}
	defer file.Close()

	if header.Size > maxBytes {
		c.JSON(http.StatusBadRequest, gin.H{"code": 400, "message": fmt.Sprintf("文件不能超过 %d MB", h.cfg.MaxUploadMB)})
		return
	}

	// 嗅探 MIME
	head := make([]byte, 512)
	n, _ := io.ReadFull(file, head)
	contentType := http.DetectContentType(head[:n])
	// 复位读取：拼回 head + 剩余
	reader := io.MultiReader(bytes.NewReader(head[:n]), file)

	// 部分浏览器 Content-Type 不准，也允许 header 中的 type
	if !media.AllowedUploadMIME(contentType) {
		ct := header.Header.Get("Content-Type")
		if media.AllowedUploadMIME(ct) {
			contentType = ct
		} else {
			// 按扩展名兜底
			ext := strings.ToLower(path.Ext(header.Filename))
			switch ext {
			case ".jpg", ".jpeg":
				contentType = "image/jpeg"
			case ".png":
				contentType = "image/png"
			case ".gif":
				contentType = "image/gif"
			case ".webp":
				contentType = "image/webp"
			default:
				c.JSON(http.StatusBadRequest, gin.H{"code": 400, "message": "仅支持 jpg/png/gif/webp 图片"})
				return
			}
		}
	}
	_ = contentType

	raw, err := io.ReadAll(reader)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"code": 400, "message": "读取文件失败"})
		return
	}
	if int64(len(raw)) > maxBytes {
		c.JSON(http.StatusBadRequest, gin.H{"code": 400, "message": "文件过大"})
		return
	}

	processed, err := media.ProcessImage(bytes.NewReader(raw), media.ProcessOptions{
		MaxEdge:     h.cfg.MaxImageEdge,
		ThumbEdge:   400,
		WebPQuality: h.cfg.WebPQuality,
	})
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"code": 400, "message": err.Error()})
		return
	}

	mainKey := storage.NewObjectKey(keyPrefix, processed.MainExt)
	thumbKey := storage.NewObjectKey(keyPrefix+"/thumbs", processed.ThumbExt)

	mainURL, err := h.store.Put(c.Request.Context(), mainKey, bytes.NewReader(processed.Main), int64(len(processed.Main)), processed.MainType)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"code": 500, "message": "上传失败: " + err.Error()})
		return
	}
	thumbURL, err := h.store.Put(c.Request.Context(), thumbKey, bytes.NewReader(processed.Thumb), int64(len(processed.Thumb)), processed.ThumbType)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"code": 500, "message": "缩略图上传失败: " + err.Error()})
		return
	}

	middleware.JSON(c, gin.H{
		"url":          mainURL,
		"thumb_url":    thumbURL,
		"content_type": processed.MainType,
		"width":        processed.Width,
		"height":       processed.Height,
		"size":         len(processed.Main),
	})
}