package handler

import (
	"errors"
	"io"
	"mime"
	"net/http"
	"path"
	"strconv"
	"time"

	"github.com/freefire/jiang13-bbs/middleware"
	"github.com/freefire/jiang13-bbs/model"
	"github.com/freefire/jiang13-bbs/service"
	"github.com/gin-gonic/gin"
)

// UploadAvatar 上传裁剪后的头像（multipart 字段 file，内容必须是 WebP）
func (h *Handlers) UploadAvatar(c *gin.Context) {
	claims := middleware.CurrentUser(c)

	// 限制请求体：以裁剪后文件为依据，允许少量 multipart 边界开销
	c.Request.Body = http.MaxBytesReader(c.Writer, c.Request.Body, service.AvatarMaxBytes+4096)

	fh, err := c.FormFile("file")
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "图片过大（裁剪后不能超过 2MB）或格式不正确"})
		return
	}
	if fh.Size > service.AvatarMaxBytes {
		c.JSON(http.StatusBadRequest, gin.H{"error": "裁剪后的图片不能超过 2MB"})
		return
	}
	f, err := fh.Open()
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "读取图片失败"})
		return
	}
	defer f.Close()

	// fh.Size 已受 MaxBytesReader 约束；读取时二次防御
	data, err := io.ReadAll(io.LimitReader(f, service.AvatarMaxBytes+1))
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "读取图片失败"})
		return
	}

	att, err := h.Upload.SaveAvatar(claims.ID, data)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	c.JSON(http.StatusOK, gin.H{"url": att.URL, "attachment": att})
}

// UploadImage 上传帖子插图（multipart 字段 file：JPEG / PNG / WebP / GIF；除 GIF 外自动转存 WebP）
func (h *Handlers) UploadImage(c *gin.Context) {
	claims := middleware.CurrentUser(c)

	maxBytes, err := h.Setting.ImageMaxBytes()
	if err != nil || maxBytes < 1 {
		maxBytes = service.ImageMaxBytes
	}
	overhead := int64(4096)
	limit := maxBytes + overhead

	if c.Request.ContentLength > limit {
		mb := int(maxBytes >> 20)
		if mb < 1 {
			mb = 1
		}
		c.JSON(http.StatusRequestEntityTooLarge, gin.H{"error": "图片不能超过 " + strconv.Itoa(mb) + "MB"})
		return
	}
	c.Request.Body = http.MaxBytesReader(c.Writer, c.Request.Body, limit)

	fh, err := c.FormFile("file")
	if err != nil {
		var maxErr *http.MaxBytesError
		if errors.As(err, &maxErr) {
			mb := int(maxBytes >> 20)
			if mb < 1 {
				mb = 1
			}
			c.JSON(http.StatusRequestEntityTooLarge, gin.H{"error": "图片不能超过 " + strconv.Itoa(mb) + "MB"})
			return
		}
		c.JSON(http.StatusBadRequest, gin.H{"error": "图片过大或格式不正确"})
		return
	}
	if fh.Size > maxBytes {
		mb := int(maxBytes >> 20)
		if mb < 1 {
			mb = 1
		}
		c.JSON(http.StatusBadRequest, gin.H{"error": "图片不能超过 " + strconv.Itoa(mb) + "MB"})
		return
	}
	f, err := fh.Open()
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "读取图片失败"})
		return
	}
	defer f.Close()

	att, err := h.Upload.SaveImage(claims.ID, f, c.PostForm("source"))
	if err != nil {
		var maxErr *http.MaxBytesError
		if errors.As(err, &maxErr) {
			mb := int(maxBytes >> 20)
			if mb < 1 {
				mb = 1
			}
			c.JSON(http.StatusRequestEntityTooLarge, gin.H{"error": "图片不能超过 " + strconv.Itoa(mb) + "MB"})
			return
		}
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	c.JSON(http.StatusOK, gin.H{"url": att.URL, "attachment": att})
}

// UseAvatarRequest 选用历史头像请求
type UseAvatarRequest struct {
	URL string `json:"url"`
}

// UseAvatar 选用本人历史上传的头像
func (h *Handlers) UseAvatar(c *gin.Context) {
	claims := middleware.CurrentUser(c)
	var req UseAvatarRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "请求参数格式错误"})
		return
	}
	if err := h.Upload.UseAvatar(claims.ID, req.URL); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	c.JSON(http.StatusOK, gin.H{"url": req.URL})
}

// MyMedia 媒体库：本人上传的全部图片（头像、帖子插图等）
func (h *Handlers) MyMedia(c *gin.Context) {
	claims := middleware.CurrentUser(c)
	list, err := h.Upload.ListMedia(claims.ID)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}
	c.JSON(http.StatusOK, gin.H{"attachments": nonNilSlice(list)})
}

// DeleteAttachment 彻底删除本人附件（DB + 物理文件）
func (h *Handlers) DeleteAttachment(c *gin.Context) {
	claims := middleware.CurrentUser(c)
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "无效的附件 ID"})
		return
	}
	if err := h.Upload.DeleteAttachment(claims.ID, uint(id)); err != nil {
		if errors.Is(err, service.ErrAttachmentInUse) {
			c.JSON(http.StatusConflict, gin.H{"error": err.Error()})
			return
		}
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	c.JSON(http.StatusOK, gin.H{"ok": true})
}

// UploadBackground 超管上传站点背景图（JPEG/PNG/WebP），只落盘返回 URL，不写站点设置
func (h *Handlers) UploadBackground(c *gin.Context) {
	if _, ok := service.NormalizeBgSurface(c.PostForm("surface")); !ok {
		c.JSON(http.StatusBadRequest, gin.H{"error": "请指定前台或后台（surface=site|admin）"})
		return
	}

	limit := int64(service.BackgroundMaxBytes + 4096)
	c.Request.Body = http.MaxBytesReader(c.Writer, c.Request.Body, limit)

	fh, err := c.FormFile("file")
	if err != nil {
		var maxErr *http.MaxBytesError
		if errors.As(err, &maxErr) {
			c.JSON(http.StatusRequestEntityTooLarge, gin.H{"error": "背景图不能超过 8MB"})
			return
		}
		c.JSON(http.StatusBadRequest, gin.H{"error": "图片过大或格式不正确"})
		return
	}
	if fh.Size > service.BackgroundMaxBytes {
		c.JSON(http.StatusRequestEntityTooLarge, gin.H{"error": "背景图不能超过 8MB"})
		return
	}
	f, err := fh.Open()
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "读取图片失败"})
		return
	}
	defer f.Close()

	url, err := h.Upload.SaveBackground(f)
	if err != nil {
		var maxErr *http.MaxBytesError
		if errors.As(err, &maxErr) {
			c.JSON(http.StatusRequestEntityTooLarge, gin.H{"error": "背景图不能超过 8MB"})
			return
		}
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	c.JSON(http.StatusOK, gin.H{"url": url})
}

type backgroundFromMediaRequest struct {
	AttachmentID uint   `json:"attachment_id"`
	Surface      string `json:"surface"`
}

// UploadBackgroundFromMedia 把本人媒体库图片复制进 backgrounds，不写站点设置
func (h *Handlers) UploadBackgroundFromMedia(c *gin.Context) {
	var req backgroundFromMediaRequest
	if err := c.ShouldBindJSON(&req); err != nil || req.AttachmentID == 0 {
		c.JSON(http.StatusBadRequest, gin.H{"error": "请选择媒体库中的图片"})
		return
	}
	if _, ok := service.NormalizeBgSurface(req.Surface); !ok {
		c.JSON(http.StatusBadRequest, gin.H{"error": "请指定前台或后台（surface=site|admin）"})
		return
	}
	claims := middleware.CurrentUser(c)
	if claims == nil {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "请先登录"})
		return
	}
	url, err := h.Upload.CopyBackgroundFromMedia(claims.ID, req.AttachmentID)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	c.JSON(http.StatusOK, gin.H{"url": url})
}

// UploadBrand 超管上传 Logo / Favicon，只落盘返回 URL，不写站点设置
func (h *Handlers) UploadBrand(c *gin.Context) {
	slot := c.PostForm("slot")
	if _, ok := service.NormalizeBrandSlot(slot); !ok {
		c.JSON(http.StatusBadRequest, gin.H{"error": "请指定 logo_light、logo_dark 或 favicon"})
		return
	}
	maxB := int64(service.BrandLogoMaxBytes)
	if slot == service.BrandSlotFavicon {
		maxB = service.BrandFaviconMaxBytes
	}
	c.Request.Body = http.MaxBytesReader(c.Writer, c.Request.Body, maxB+4096)

	fh, err := c.FormFile("file")
	if err != nil {
		var maxErr *http.MaxBytesError
		if errors.As(err, &maxErr) {
			c.JSON(http.StatusRequestEntityTooLarge, gin.H{"error": brandTooLarge(slot)})
			return
		}
		c.JSON(http.StatusBadRequest, gin.H{"error": "图片过大或格式不正确"})
		return
	}
	if fh.Size > maxB {
		c.JSON(http.StatusRequestEntityTooLarge, gin.H{"error": brandTooLarge(slot)})
		return
	}
	f, err := fh.Open()
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "读取图片失败"})
		return
	}
	defer f.Close()

	url, err := h.Upload.SaveBrand(slot, f)
	if err != nil {
		var maxErr *http.MaxBytesError
		if errors.As(err, &maxErr) {
			c.JSON(http.StatusRequestEntityTooLarge, gin.H{"error": brandTooLarge(slot)})
			return
		}
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	c.JSON(http.StatusOK, gin.H{"url": url})
}

type brandFromMediaRequest struct {
	AttachmentID uint   `json:"attachment_id"`
	Slot         string `json:"slot"`
}

// UploadBrandFromMedia 把本人媒体库图片复制进品牌目录，不写站点设置
func (h *Handlers) UploadBrandFromMedia(c *gin.Context) {
	var req brandFromMediaRequest
	if err := c.ShouldBindJSON(&req); err != nil || req.AttachmentID == 0 {
		c.JSON(http.StatusBadRequest, gin.H{"error": "请选择媒体库中的图片"})
		return
	}
	claims := middleware.CurrentUser(c)
	if claims == nil {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "请先登录"})
		return
	}
	url, err := h.Upload.CopyBrandFromMedia(claims.ID, req.AttachmentID, req.Slot)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	c.JSON(http.StatusOK, gin.H{"url": url})
}

// UploadLibraryCoverFromMedia 把本人媒体库图片用作书籍封面素材。
// 若该图已是封面类型（source=library_cover），直接复用原记录，不再复制；
// 否则复制一份并标记为封面类型（与原图解耦，删除原图不影响封面）。
func (h *Handlers) UploadLibraryCoverFromMedia(c *gin.Context) {
	var req struct {
		AttachmentID uint `json:"attachment_id"`
	}
	if err := c.ShouldBindJSON(&req); err != nil || req.AttachmentID == 0 {
		c.JSON(http.StatusBadRequest, gin.H{"error": "请选择媒体库中的图片"})
		return
	}
	claims := middleware.CurrentUser(c)
	if claims == nil {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "请先登录"})
		return
	}

	// 已是封面类型的图直接复用，避免重复复制产生冗余记录
	if existing, err := h.Upload.FindMediaBySource(claims.ID, req.AttachmentID, model.AttachmentSourceLibraryCover); err == nil {
		c.JSON(http.StatusOK, gin.H{"url": existing.URL, "attachment": existing})
		return
	}

	att, err := h.Upload.CopyImageFromMedia(claims.ID, req.AttachmentID, model.AttachmentSourceLibraryCover)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	c.JSON(http.StatusOK, gin.H{"url": att.URL, "attachment": att})
}

// brandAliasSlots 固定地址路径段 → 品牌槽位
var brandAliasSlots = map[string]string{
	"logo-light": service.BrandSlotLight,
	"logo-dark":  service.BrandSlotDark,
	"favicon":    service.BrandSlotFavicon,
}

// BrandImage 品牌图固定对外地址（GET /api/brand/logo-light|logo-dark|favicon）：
// 友链等外部引用此地址，站点换图后按设置解析到当前图，地址永不变。
func (h *Handlers) BrandImage(c *gin.Context) {
	slot, ok := brandAliasSlots[c.Param("slot")]
	if !ok {
		c.Status(http.StatusNotFound)
		return
	}
	var url string
	var err error
	switch slot {
	case service.BrandSlotLight:
		url, err = h.Setting.LogoLightURL()
	case service.BrandSlotDark:
		url, err = h.Setting.LogoDarkURL()
	default:
		url, err = h.Setting.FaviconURL()
	}
	if err != nil {
		c.Status(http.StatusInternalServerError)
		return
	}
	if url == "" {
		c.Status(http.StatusNotFound)
		return
	}
	f, err := h.Upload.OpenBrandFile(url)
	if err != nil {
		c.Status(http.StatusNotFound)
		return
	}
	defer f.Close()
	// 扩展名定 Content-Type（SVG 不能靠嗅探）；短缓存让换图在友链侧尽快生效
	if ct := mime.TypeByExtension(path.Ext(url)); ct != "" {
		c.Header("Content-Type", ct)
	}
	c.Header("Cache-Control", "public, max-age=3600")
	http.ServeContent(c.Writer, c.Request, path.Base(url), time.Time{}, f)
}

// AdminMediaLibrary 管理后台媒体库：全站图片盘点（磁盘五类目录 + 附件元数据）
func (h *Handlers) AdminMediaLibrary(c *gin.Context) {
	items, counts, err := h.Upload.AdminMediaLibrary()
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "读取媒体库失败"})
		return
	}
	c.JSON(http.StatusOK, gin.H{"items": nonNilSlice(items), "counts": counts, "total": len(items)})
}

// MediaLibraryThumb 媒体库网格缩略图（?u=/uploads/images/xx.webp），失败回退由前端处理
func (h *Handlers) MediaLibraryThumb(c *gin.Context) {
	data, err := h.Upload.MediaThumb(c.Query("u"))
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "缩略图不可用"})
		return
	}
	c.Header("Cache-Control", "private, max-age=86400")
	c.Data(http.StatusOK, "image/webp", data)
}

// ImageVariant 公开图片变体（GET /api/img?u=<源图URL>&w=<白名单宽度>）：
// 供全站 srcset 消费，源内容不可变 → immutable 长缓存；失败 404 由前端 onError 兜底
func (h *Handlers) ImageVariant(c *gin.Context) {
	w, err := strconv.Atoi(c.Query("w"))
	if err != nil || !service.IsVariantWidth(w) {
		c.JSON(http.StatusBadRequest, gin.H{"error": "不支持的尺寸"})
		return
	}
	data, m, err := h.Upload.Variant(c.Query("u"), w)
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "图片不可用"})
		return
	}
	c.Header("Cache-Control", "public, max-age=31536000, immutable")
	c.Data(http.StatusOK, m, data)
}

func brandTooLarge(slot string) string {
	if slot == service.BrandSlotFavicon {
		return "Favicon 不能超过 512KB"
	}
	return "Logo 不能超过 2MB"
}