feat: 类型帖互动、积分经济与发帖体验

补齐问答采纳/重开、投票匿名与有票禁编、悬赏过期退回、抽奖回帖开奖，并接入积分账本与发帖附件可见性。

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/handler/post_interact.go

@@ -0,0 +1,197 @@
+package handler
+
+import (
+	"errors"
+	"net/http"
+	"strconv"
+
+	"github.com/freefire/jiang13-bbs/middleware"
+	"github.com/freefire/jiang13-bbs/service"
+	"github.com/gin-gonic/gin"
+)
+
+func (h *Handlers) respondInteractError(c *gin.Context, err error) {
+	switch {
+	case errors.Is(err, service.ErrPostNotFound):
+		c.JSON(http.StatusNotFound, gin.H{"error": err.Error()})
+	case errors.Is(err, service.ErrPostForbidden):
+		c.JSON(http.StatusForbidden, gin.H{"error": err.Error()})
+	case errors.Is(err, service.ErrInsufficientPoints):
+		c.JSON(http.StatusPaymentRequired, gin.H{"error": err.Error()})
+	case errors.Is(err, service.ErrAlreadyVoted),
+		errors.Is(err, service.ErrPollClosed),
+		errors.Is(err, service.ErrPollOptionsLocked),
+		errors.Is(err, service.ErrLotteryDrawn),
+		errors.Is(err, service.ErrLotteryClosed),
+		errors.Is(err, service.ErrBountySettled),
+		errors.Is(err, service.ErrBountyExpired):
+		c.JSON(http.StatusConflict, gin.H{"error": err.Error()})
+	default:
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+	}
+}
+
+// VotePoll 投票
+func (h *Handlers) VotePoll(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": "无效的帖子 ID"})
+		return
+	}
+	var req struct {
+		Options []int `json:"options"`
+	}
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "参数错误"})
+		return
+	}
+	post, err := h.Post.VotePoll(claims.ID, uint(id), req.Options)
+	if err != nil {
+		h.respondInteractError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"post": post})
+}
+
+// ClosePoll 结束投票
+func (h *Handlers) ClosePoll(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": "无效的帖子 ID"})
+		return
+	}
+	post, err := h.Post.ClosePoll(h.loadActor(claims.ID), claims.ID, uint(id))
+	if err != nil {
+		h.respondInteractError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"post": post})
+}
+
+// AcceptQuestion 采纳问答答案
+func (h *Handlers) AcceptQuestion(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": "无效的帖子 ID"})
+		return
+	}
+	var req struct {
+		CommentID uint `json:"comment_id" binding:"required"`
+	}
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "请指定评论"})
+		return
+	}
+	post, err := h.Post.AcceptQuestion(h.loadActor(claims.ID), claims.ID, uint(id), req.CommentID)
+	if err != nil {
+		h.respondInteractError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"post": post})
+}
+
+// SolveQuestion 手动标已解决
+func (h *Handlers) SolveQuestion(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": "无效的帖子 ID"})
+		return
+	}
+	post, err := h.Post.SolveQuestion(h.loadActor(claims.ID), claims.ID, uint(id))
+	if err != nil {
+		h.respondInteractError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"post": post})
+}
+
+// ReopenQuestion 重新打开问答
+func (h *Handlers) ReopenQuestion(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": "无效的帖子 ID"})
+		return
+	}
+	post, err := h.Post.ReopenQuestion(h.loadActor(claims.ID), claims.ID, uint(id))
+	if err != nil {
+		h.respondInteractError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"post": post})
+}
+
+// AcceptBounty 采纳评论并发放悬赏
+func (h *Handlers) AcceptBounty(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": "无效的帖子 ID"})
+		return
+	}
+	var req struct {
+		CommentID uint `json:"comment_id" binding:"required"`
+	}
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "请指定评论"})
+		return
+	}
+	post, err := h.Post.AcceptBounty(h.loadActor(claims.ID), claims.ID, uint(id), req.CommentID)
+	if err != nil {
+		h.respondInteractError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"post": post})
+}
+
+// RefundBounty 退回悬赏
+func (h *Handlers) RefundBounty(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": "无效的帖子 ID"})
+		return
+	}
+	post, err := h.Post.RefundBounty(h.loadActor(claims.ID), claims.ID, uint(id))
+	if err != nil {
+		h.respondInteractError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"post": post})
+}
+
+// CloseLottery 截止抽奖
+func (h *Handlers) CloseLottery(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": "无效的帖子 ID"})
+		return
+	}
+	post, err := h.Post.CloseLotteryEntries(h.loadActor(claims.ID), claims.ID, uint(id))
+	if err != nil {
+		h.respondInteractError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"post": post})
+}
+
+// DrawLottery 开奖
+func (h *Handlers) DrawLottery(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": "无效的帖子 ID"})
+		return
+	}
+	post, err := h.Post.DrawLottery(h.loadActor(claims.ID), claims.ID, uint(id))
+	if err != nil {
+		h.respondInteractError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"post": post})
+}