package handler

import (
	"bytes"
	"errors"
	"fmt"
	"io"
	"log"
	"mime/multipart"
	"net/http"
	"path"
	"regexp"
	"strings"
	"time"

	"github.com/gin-gonic/gin"

	"wx_service/config"
	"wx_service/internal/common/imageutil"
	oss "wx_service/internal/common/oss"
	uploadservice "wx_service/internal/common/upload/service"
	"wx_service/internal/marketing/service"
	"wx_service/internal/middleware"
	"wx_service/internal/model"
)

var adminExtPattern = regexp.MustCompile(`^\.[a-z0-9]{1,10}$`)

type DownloadHandler struct {
	svc *service.DownloadService
}

func NewDownloadHandler(svc *service.DownloadService) *DownloadHandler {
	return &DownloadHandler{svc: svc}
}

func (h *DownloadHandler) Create(c *gin.Context) {
	user := middleware.MustCurrentUser(c)

	var req service.CreateDownloadRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, model.Error(http.StatusBadRequest, "请求参数错误"))
		return
	}

	dl, err := h.svc.Create(user.ID, req)
	if err != nil {
		if service.IsNotFoundError(err) {
			c.JSON(http.StatusNotFound, model.Error(http.StatusNotFound, "模板不存在"))
			return
		}
		if service.IsBadRequestError(err) {
			c.JSON(http.StatusBadRequest, model.Error(http.StatusBadRequest, err.Error()))
			return
		}
		c.JSON(http.StatusInternalServerError, model.Error(http.StatusInternalServerError, "服务器错误"))
		return
	}

	c.JSON(http.StatusOK, model.Success(dl))
}

type adCallbackRequest struct {
	DownloadID uint `json:"download_id" binding:"required"`
}

func (h *DownloadHandler) AdCallback(c *gin.Context) {
	var req adCallbackRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, model.Error(http.StatusBadRequest, "请求参数错误"))
		return
	}

	if err := h.svc.MarkAdCompleted(req.DownloadID); err != nil {
		if service.IsNotFoundError(err) {
			c.JSON(http.StatusNotFound, model.Error(http.StatusNotFound, "记录不存在"))
			return
		}
		c.JSON(http.StatusInternalServerError, model.Error(http.StatusInternalServerError, "服务器错误"))
		return
	}

	c.JSON(http.StatusOK, model.Success(nil))
}

func (h *DownloadHandler) ListByUser(c *gin.Context) {
	user := middleware.MustCurrentUser(c)
	page := parseIntQuery(c, "page", 1)
	pageSize := parseIntQuery(c, "page_size", 20)

	resp, err := h.svc.ListByUser(user.ID, page, pageSize)
	if err != nil {
		c.JSON(http.StatusInternalServerError, model.Error(http.StatusInternalServerError, "服务器错误"))
		return
	}

	c.JSON(http.StatusOK, model.Success(resp))
}

func (h *DownloadHandler) AdminStats(c *gin.Context) {
	stats, err := h.svc.GetStats()
	if err != nil {
		c.JSON(http.StatusInternalServerError, model.Error(http.StatusInternalServerError, "服务器错误"))
		return
	}
	c.JSON(http.StatusOK, model.Success(stats))
}

type adminUploadTokenRequest struct {
	Filename string `json:"filename"`
}

type adminUploadTokenResponse struct {
	Token        string `json:"token,omitempty"`
	Key          string `json:"key"`
	UploadURL    string `json:"upload_url"`
	ExpireAt     int64  `json:"expire,omitempty"`
	CDNDomain    string `json:"cdn_domain,omitempty"`
	OSSAccessKey string `json:"oss_access_key_id,omitempty"`
	OSSPolicy    string `json:"oss_policy,omitempty"`
	OSSSignature string `json:"oss_signature,omitempty"`
}

func (h *DownloadHandler) AdminUploadToken(c *gin.Context) {
	var req adminUploadTokenRequest
	_ = c.ShouldBindJSON(&req)

	cfg := config.AppConfig.OSS
	if cfg.AccessKey == "" || cfg.SecretKey == "" || cfg.Bucket == "" {
		c.JSON(http.StatusServiceUnavailable, model.Error(http.StatusServiceUnavailable, "未配置上传服务"))
		return
	}

	cdnDomain := strings.TrimSpace(cfg.CDNDomain)

	if oss.IsOSSDomain(cdnDomain) {
		ext := path.Ext(req.Filename)
		if ext == "" || !adminExtPattern.MatchString(strings.ToLower(ext)) {
			ext = ".jpg"
		}
		keyPrefix := strings.Trim(cfg.KeyPrefix, "/")
		key := fmt.Sprintf("%s/admin/%s/%x%s",
			keyPrefix, time.Now().Format("20060102"), time.Now().UnixNano()&0xffffffff, ext)
		endpoint := oss.ParseOSSEndpoint(cdnDomain)
		expireSeconds := cfg.TokenExpireSeconds
		if expireSeconds <= 0 {
			expireSeconds = 300
		}
		policy, signature, err := oss.PostPolicy(cfg.Bucket, endpoint, key, cfg.SecretKey, expireSeconds)
		if err != nil {
			c.JSON(http.StatusInternalServerError, model.Error(http.StatusInternalServerError, "生成上传凭证失败"))
			return
		}
		uploadURL := oss.UploadHost(cfg.Bucket, endpoint)
		cdnHost := "https://" + cfg.Bucket + "." + endpoint + ".aliyuncs.com"
		c.JSON(http.StatusOK, model.Success(adminUploadTokenResponse{
			Key:          key,
			UploadURL:    uploadURL,
			CDNDomain:    cdnHost,
			OSSAccessKey: cfg.AccessKey,
			OSSPolicy:    policy,
			OSSSignature: signature,
		}))
		return
	}

	uploadSvc := uploadservice.NewUploadService(cfg)
	token, err := uploadSvc.CreateUploadToken(0, 0, req.Filename)
	if err != nil {
		if errors.Is(err, uploadservice.ErrUploadNotConfigured) {
			c.JSON(http.StatusServiceUnavailable, model.Error(http.StatusServiceUnavailable, "未配置上传服务"))
			return
		}
		c.JSON(http.StatusInternalServerError, model.Error(http.StatusInternalServerError, "获取上传凭证失败"))
		return
	}

	c.JSON(http.StatusOK, model.Success(token))
}

// AdminUploadFile 接收管理后台上传的文件，服务端代理转发到 OSS，
// 同时自动生成一张压缩缩略图一并上传，减少 CDN 占用。
func (h *DownloadHandler) AdminUploadFile(c *gin.Context) {
	file, header, err := c.Request.FormFile("file")
	if err != nil {
		c.JSON(http.StatusBadRequest, model.Error(http.StatusBadRequest, "请选择要上传的文件"))
		return
	}
	defer file.Close()

	if header.Size > 10*1024*1024 {
		c.JSON(http.StatusBadRequest, model.Error(http.StatusBadRequest, "文件大小不能超过 10MB"))
		return
	}

	cfg := config.AppConfig.OSS
	if cfg.AccessKey == "" || cfg.SecretKey == "" || cfg.Bucket == "" {
		c.JSON(http.StatusServiceUnavailable, model.Error(http.StatusServiceUnavailable, "未配置上传服务"))
		return
	}

	cdnDomain := strings.TrimSpace(cfg.CDNDomain)
	if !oss.IsOSSDomain(cdnDomain) {
		c.JSON(http.StatusServiceUnavailable, model.Error(http.StatusServiceUnavailable, "仅支持 OSS 上传"))
		return
	}

	fileData, err := io.ReadAll(file)
	if err != nil {
		c.JSON(http.StatusInternalServerError, model.Error(http.StatusInternalServerError, "读取文件失败"))
		return
	}

	ext := strings.ToLower(path.Ext(header.Filename))
	if ext == "" || !adminExtPattern.MatchString(ext) {
		ext = ".jpg"
	}
	keyPrefix := strings.Trim(cfg.KeyPrefix, "/")
	ts := fmt.Sprintf("%x", time.Now().UnixNano()&0xffffffff)
	origKey := fmt.Sprintf("%s/admin/%s/%s%s", keyPrefix, time.Now().Format("20060102"), ts, ext)
	thumbKey := fmt.Sprintf("%s/admin/%s/%s_thumb.jpg", keyPrefix, time.Now().Format("20060102"), ts)

	endpoint := oss.ParseOSSEndpoint(cdnDomain)
	cdnHost := "https://" + cfg.Bucket + "." + endpoint + ".aliyuncs.com"

	origURL, err := uploadToOSS(cfg, endpoint, origKey, header.Filename, fileData)
	if err != nil {
		log.Printf("[admin_upload] upload original error: %v", err)
		c.JSON(http.StatusBadGateway, model.Error(http.StatusBadGateway, "上传原图到 OSS 失败"))
		return
	}

	thumbURL := ""
	thumbData, thumbErr := imageutil.GenerateThumbnail(fileData, header.Header.Get("Content-Type"), imageutil.DefaultResizeOptions())
	if thumbErr != nil {
		log.Printf("[admin_upload] thumbnail generation skipped: %v", thumbErr)
	} else {
		if url, err := uploadToOSS(cfg, endpoint, thumbKey, "thumb.jpg", thumbData); err != nil {
			log.Printf("[admin_upload] upload thumbnail error: %v", err)
		} else {
			thumbURL = url
		}
	}

	if origURL == "" {
		origURL = cdnHost + "/" + origKey
	}

	result := gin.H{"url": origURL}
	if thumbURL != "" {
		result["thumbnail_url"] = thumbURL
	}
	c.JSON(http.StatusOK, model.Success(result))
}

func uploadToOSS(cfg config.OSSConfig, endpoint, key, filename string, data []byte) (string, error) {
	expireSeconds := cfg.TokenExpireSeconds
	if expireSeconds <= 0 {
		expireSeconds = 300
	}
	policy, signature, err := oss.PostPolicy(cfg.Bucket, endpoint, key, cfg.SecretKey, expireSeconds)
	if err != nil {
		return "", fmt.Errorf("generate policy: %w", err)
	}

	uploadURL := oss.UploadHost(cfg.Bucket, endpoint)
	var body bytes.Buffer
	writer := multipart.NewWriter(&body)
	writer.WriteField("key", key)
	writer.WriteField("policy", policy)
	writer.WriteField("OSSAccessKeyId", cfg.AccessKey)
	writer.WriteField("Signature", signature)
	fw, err := writer.CreateFormFile("file", filename)
	if err != nil {
		return "", fmt.Errorf("create form file: %w", err)
	}
	fw.Write(data)
	writer.Close()

	req, err := http.NewRequest(http.MethodPost, uploadURL, &body)
	if err != nil {
		return "", fmt.Errorf("new request: %w", err)
	}
	req.Header.Set("Content-Type", writer.FormDataContentType())

	client := &http.Client{Timeout: 60 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		return "", fmt.Errorf("do request: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		respBody, _ := io.ReadAll(resp.Body)
		return "", fmt.Errorf("oss status=%d body=%s", resp.StatusCode, string(respBody))
	}

	cdnHost := "https://" + cfg.Bucket + "." + endpoint + ".aliyuncs.com"
	return cdnHost + "/" + key, nil
}