package handler

import (
	"archive/zip"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	"github.com/gin-gonic/gin"
	"note-manager/model"
	"note-manager/service"
)

// NoteHandler 笔记请求处理器
type NoteHandler struct {
	svc *service.NoteService
}

// NewNoteHandler 创建处理器实例
func NewNoteHandler(svc *service.NoteService) *NoteHandler {
	return &NoteHandler{svc: svc}
}

// Response 通用响应结构
type Response struct {
	Code    int         `json:"code"`
	Message string      `json:"message"`
	Data    interface{} `json:"data,omitempty"`
}

// PageResponse 分页响应结构
type PageResponse struct {
	Code       int         `json:"code"`
	Message    string      `json:"message"`
	Data       interface{} `json:"data"`
	Total      int64       `json:"total"`
	Page       int         `json:"page"`
	PageSize   int         `json:"page_size"`
	TotalPages int         `json:"total_pages"`
}

func success(c *gin.Context, data interface{}) {
	c.JSON(http.StatusOK, Response{Code: 0, Message: "success", Data: data})
}

func fail(c *gin.Context, status int, msg string) {
	c.JSON(status, Response{Code: -1, Message: msg})
}

// CreateNote 创建笔记
func (h *NoteHandler) CreateNote(c *gin.Context) {
	var req model.NoteCreateRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		fail(c, http.StatusBadRequest, "请求参数错误: "+err.Error())
		return
	}

	note, err := h.svc.CreateNote(req)
	if err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}

	success(c, note)
}

// GetNote 获取笔记详情（公开只读接口）
// 安全策略：仅允许返回「公开且无密码」的笔记。有密码或未公开的笔记一律返回需授权提示，
// 防止通过该接口绕过密码保护读取内容。
func (h *NoteHandler) GetNote(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的笔记 ID")
		return
	}

	note, err := h.svc.GetNote(uint(id))
	if err != nil {
		fail(c, http.StatusNotFound, err.Error())
		return
	}

	// 公开接口白名单：仅公开且无密码的笔记返回完整内容
	if !note.IsPublic || note.Password != "" {
		fail(c, http.StatusForbidden, "该笔记受保护，无法直接访问")
		return
	}

	success(c, note)
}

// GetAdminNote 获取笔记详情（管理后台用，返回完整内容）
func (h *NoteHandler) GetAdminNote(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的笔记 ID")
		return
	}

	note, err := h.svc.GetNote(uint(id))
	if err != nil {
		fail(c, http.StatusNotFound, err.Error())
		return
	}

	success(c, note)
}

// AccessNote 验证密码后获取笔记内容
func (h *NoteHandler) AccessNote(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的笔记 ID")
		return
	}

	var req struct {
		Password string `json:"password"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		// 没有密码参数，尝试从 URL 参数获取
		req.Password = c.Query("password")
	}

	note, upgrade, err := h.svc.GetNoteContent(uint(id), req.Password)
	if err != nil {
		if err.Error() == "密码错误" {
			fail(c, http.StatusUnauthorized, err.Error())
			return
		}
		fail(c, http.StatusNotFound, err.Error())
		return
	}

	// 若旧 SHA-256 哈希命中，自动升级为 bcrypt
	if upgrade {
		_ = h.svc.UpgradePasswordHash(note.ID, req.Password)
	}

	success(c, note)
}

// UpdateNote 更新笔记
func (h *NoteHandler) UpdateNote(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的笔记 ID")
		return
	}

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

	note, err := h.svc.UpdateNote(uint(id), req)
	if err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}

	success(c, note)
}

// DeleteNote 删除笔记（软删除，进入回收站）
func (h *NoteHandler) DeleteNote(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的笔记 ID")
		return
	}

	if err := h.svc.DeleteNote(uint(id)); err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}

	success(c, nil)
}

// ListNotes 获取笔记列表
func (h *NoteHandler) ListNotes(c *gin.Context) {
	var pinned *bool
	if v := c.Query("pinned"); v != "" {
		b := v == "true" || v == "1"
		pinned = &b
	}
	var favorite *bool
	if v := c.Query("favorite"); v != "" {
		b := v == "true" || v == "1"
		favorite = &b
	}

	items, total, totalPages, err := h.svc.ListNotes(
		c.DefaultQuery("page", "1"),
		c.DefaultQuery("page_size", ""),
		c.Query("category"),
		c.Query("tag"),
		pinned,
		favorite,
	)
	if err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}

	page := parseIntDefault(c.DefaultQuery("page", "1"), 1)
	pageSize := parseIntDefault(c.DefaultQuery("page_size", "20"), 20)

	c.JSON(http.StatusOK, PageResponse{
		Code:       0,
		Message:    "success",
		Data:       items,
		Total:      total,
		Page:       page,
		PageSize:   pageSize,
		TotalPages: totalPages,
	})
}

// SearchNotes 搜索笔记
func (h *NoteHandler) SearchNotes(c *gin.Context) {
	keyword := c.Query("q")
	items, total, totalPages, err := h.svc.SearchNotes(
		keyword,
		c.DefaultQuery("page", "1"),
		c.DefaultQuery("page_size", ""),
	)
	if err != nil {
		fail(c, http.StatusBadRequest, err.Error())
		return
	}

	page := parseIntDefault(c.DefaultQuery("page", "1"), 1)
	pageSize := parseIntDefault(c.DefaultQuery("page_size", "20"), 20)

	c.JSON(http.StatusOK, PageResponse{
		Code:       0,
		Message:    "success",
		Data:       items,
		Total:      total,
		Page:       page,
		PageSize:   pageSize,
		TotalPages: totalPages,
	})
}

// GetCategories 获取分类列表
func (h *NoteHandler) GetCategories(c *gin.Context) {
	categories, err := h.svc.GetCategories()
	if err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}
	success(c, categories)
}

// GetTags 获取所有标签
func (h *NoteHandler) GetTags(c *gin.Context) {
	tags, err := h.svc.GetTags()
	if err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}
	success(c, tags)
}

// GetTree 获取树形结构（管理后台用）
func (h *NoteHandler) GetTree(c *gin.Context) {
	tree, err := h.svc.GetAllTree()
	if err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}
	success(c, tree)
}

// GetPublicTree 获取公开树形结构（前台用）
func (h *NoteHandler) GetPublicTree(c *gin.Context) {
	tree, err := h.svc.GetPublicTree()
	if err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}
	success(c, tree)
}

func parseIntDefault(s string, defaultVal int) int {
	v, err := strconv.Atoi(s)
	if err != nil {
		return defaultVal
	}
	return v
}

// ─────────────── 回收站 ───────────────

// ListTrash 回收站列表
func (h *NoteHandler) ListTrash(c *gin.Context) {
	items, err := h.svc.ListTrash()
	if err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}
	success(c, items)
}

// RestoreNote 恢复笔记
func (h *NoteHandler) RestoreNote(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的笔记 ID")
		return
	}
	if err := h.svc.RestoreNote(uint(id)); err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}
	success(c, nil)
}

// PurgeNote 彻底删除笔记
func (h *NoteHandler) PurgeNote(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的笔记 ID")
		return
	}
	if err := h.svc.PurgeNote(uint(id)); err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}
	success(c, nil)
}

// EmptyTrash 清空回收站
func (h *NoteHandler) EmptyTrash(c *gin.Context) {
	if err := h.svc.EmptyTrash(); err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}
	success(c, nil)
}

// ─────────────── 版本历史 ───────────────

// ListVersions 版本列表
func (h *NoteHandler) ListVersions(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的笔记 ID")
		return
	}
	versions, err := h.svc.ListVersions(uint(id))
	if err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}
	success(c, versions)
}

// RestoreVersion 恢复到指定版本
func (h *NoteHandler) RestoreVersion(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的笔记 ID")
		return
	}
	versionID, err := strconv.ParseUint(c.PostForm("version_id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的版本 ID")
		return
	}
	note, err := h.svc.RestoreVersion(uint(id), uint(versionID))
	if err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}
	success(c, note)
}

// ─────────────── 分享 ───────────────

// CreateShare 创建分享
func (h *NoteHandler) CreateShare(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的笔记 ID")
		return
	}
	expireHours, _ := strconv.Atoi(c.DefaultPostForm("expire_hours", "0"))
	note, err := h.svc.CreateShare(uint(id), expireHours)
	if err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}
	success(c, gin.H{
		"id":         note.ID,
		"share_token": note.ShareToken,
		"url":        "/share/" + note.ShareToken,
		"expire_at":  note.ShareExpireAt,
	})
}

// RevokeShare 撤销分享
func (h *NoteHandler) RevokeShare(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的笔记 ID")
		return
	}
	if err := h.svc.RevokeShare(uint(id)); err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}
	success(c, nil)
}

// GetSharedNote 通过令牌获取分享笔记的 JSON 接口
// 分享的笔记若设置了访问密码，则需通过 password 参数/请求体校验
func (h *NoteHandler) GetSharedNote(c *gin.Context) {
	token := c.Param("token")
	var req struct {
		Password string `json:"password"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		req.Password = c.Query("password")
	}

	note, err := h.svc.GetSharedNote(token)
	if err != nil {
		fail(c, http.StatusNotFound, err.Error())
		return
	}

	// 若分享的笔记有访问密码，校验
	if note.Password != "" {
		ok, _ := model.CheckPassword(req.Password, note.Password)
		if !ok {
			fail(c, http.StatusUnauthorized, "密码错误")
			return
		}
	}

	success(c, note)
}

// SharePage 分享阅读页（简单 HTML，展示分享的笔记内容）
func (h *NoteHandler) SharePage(c *gin.Context) {
	c.HTML(http.StatusOK, "share.html", gin.H{
		"token": c.Param("token"),
	})
}

// ExportNote 导出笔记为 Markdown 文件
func (h *NoteHandler) ExportNote(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的笔记 ID")
		return
	}

	note, err := h.svc.GetNote(uint(id))
	if err != nil {
		fail(c, http.StatusNotFound, err.Error())
		return
	}

	// 构造 Markdown（带 YAML front matter）
	content := buildMarkdown(note)

	filename := sanitizeFileName(note.Title) + ".md"
	c.Header("Content-Disposition", "attachment; filename=\""+filename+"\"")
	c.Header("Content-Type", "text/markdown; charset=utf-8")
	c.String(http.StatusOK, content)
}

// ExportAll 批量导出全部笔记为 zip
func (h *NoteHandler) ExportAll(c *gin.Context) {
	tree, err := h.svc.GetAllTree()
	if err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}

	// 构建节点 map 与根节点列表
	type node struct {
		item     model.NoteListItem
		children []*node
	}
	nodeMap := make(map[uint]*node)
	for i := range tree {
		nodeMap[tree[i].ID] = &node{item: tree[i]}
	}
	var roots []*node
	for i := range tree {
		n := nodeMap[tree[i].ID]
		if tree[i].ParentID == 0 {
			roots = append(roots, n)
		} else if p, ok := nodeMap[tree[i].ParentID]; ok {
			p.children = append(p.children, n)
		} else {
			roots = append(roots, n)
		}
	}

	c.Header("Content-Type", "application/zip")
	c.Header("Content-Disposition", "attachment; filename=notes-export.zip")
	zw := zip.NewWriter(c.Writer)
	defer zw.Close()

	var zipNotes func(n *node, path string) error
	zipNotes = func(n *node, path string) error {
		if n.item.IsFolder {
			dirPath := filepath.Join(path, sanitizeFileName(n.item.Title))
			for _, ch := range n.children {
				if err := zipNotes(ch, dirPath); err != nil {
					return err
				}
			}
			return nil
		}
		note, err := h.svc.GetNote(n.item.ID)
		if err != nil {
			return err
		}
		body := buildMarkdown(note)
		fname := filepath.Join(path, sanitizeFileName(note.Title)+".md")
		fw, err := zw.Create(fname)
		if err != nil {
			return err
		}
		_, err = fw.Write([]byte(body))
		return err
	}

	for _, root := range roots {
		if err := zipNotes(root, ""); err != nil {
			fail(c, http.StatusInternalServerError, err.Error())
			return
		}
	}
}

// ImportNotes 导入 Markdown 文件
func (h *NoteHandler) ImportNotes(c *gin.Context) {
	file, err := c.FormFile("file")
	if err != nil {
		fail(c, http.StatusBadRequest, "请选择要导入的文件")
		return
	}

	if !strings.HasSuffix(strings.ToLower(file.Filename), ".md") {
		fail(c, http.StatusBadRequest, "仅支持导入 .md 文件")
		return
	}

	// 读取文件内容
	src, err := file.Open()
	if err != nil {
		fail(c, http.StatusInternalServerError, "读取文件失败")
		return
	}
	defer src.Close()
	contentBytes, err := io.ReadAll(src)
	if err != nil {
		fail(c, http.StatusInternalServerError, "读取文件失败")
		return
	}

	// 解析 front matter
	title, body := parseFrontMatter(string(contentBytes))
	if title == "" {
		title = strings.TrimSuffix(file.Filename, ".md")
	}

	// 创建笔记
	req := model.NoteCreateRequest{
		Title:   title,
		Content: body,
	}

	note, err := h.svc.CreateNote(req)
	if err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}

	success(c, note)
}

// parseFrontMatter 解析 YAML front matter
func parseFrontMatter(content string) (title string, body string) {
	if !strings.HasPrefix(content, "---") {
		return "", content
	}

	parts := strings.SplitN(content, "---", 3)
	if len(parts) < 3 {
		return "", content
	}

	frontMatter := parts[1]
	body = strings.TrimSpace(parts[2])

	// 解析 title
	for _, line := range strings.Split(frontMatter, "\n") {
		if strings.HasPrefix(line, "title:") {
			title = strings.TrimSpace(strings.TrimPrefix(line, "title:"))
			break
		}
	}

	return title, body
}

// urlEncode URL 编码（RFC 3986）
func urlEncode(s string) string {
	return url.QueryEscape(s)
}

// buildMarkdown 将笔记构造为带 YAML front matter 的 Markdown
func buildMarkdown(note *model.Note) string {
	var b strings.Builder
	b.WriteString("---\n")
	b.WriteString("title: " + note.Title + "\n")
	if note.Category != "" {
		b.WriteString("category: " + note.Category + "\n")
	}
	// tags 是 JSON 数组字符串，转成 YAML 列表
	if note.Tags != "" {
		var tags []string
		if err := json.Unmarshal([]byte(note.Tags), &tags); err == nil && len(tags) > 0 {
			b.WriteString("tags:\n")
			for _, t := range tags {
				b.WriteString("  - " + t + "\n")
			}
		}
	}
	b.WriteString("created: " + note.CreatedAt.Format("2006-01-02 15:04:05") + "\n")
	b.WriteString("updated: " + note.UpdatedAt.Format("2006-01-02 15:04:05") + "\n")
	b.WriteString("---\n\n")
	b.WriteString(note.Content)
	return b.String()
}

// sanitizeFileName 清理文件名中的非法字符
func sanitizeFileName(name string) string {
	replacer := strings.NewReplacer("/", "_", "\\", "_", ":", "_", "*", "_", "?", "_", "\"", "_", "<", "_", ">", "_", "|", "_")
	name = replacer.Replace(name)
	name = strings.TrimSpace(name)
	if name == "" {
		return fmt.Sprintf("note-%d", time.Now().Unix())
	}
	return name
}

// ─────────────── 自动保存草稿 ───────────────

// SaveDraft 保存笔记草稿（自动保存）
func (h *NoteHandler) SaveDraft(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的笔记 ID")
		return
	}
	var req struct {
		Content string `json:"content"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		fail(c, http.StatusBadRequest, "请求参数错误")
		return
	}
	if err := h.svc.SaveDraft(uint(id), req.Content); err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}
	success(c, nil)
}

// DiscardDraft 清除指定笔记的草稿
func (h *NoteHandler) DiscardDraft(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的笔记 ID")
		return
	}
	if err := h.svc.ClearDraft(uint(id)); err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}
	success(c, nil)
}

// ─────────────── 双向链接 / 知识图谱 ───────────────

// GetBacklinks 获取指定笔记的反向链接列表
func (h *NoteHandler) GetBacklinks(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的笔记 ID")
		return
	}
	links, err := h.svc.GetBacklinks(uint(id), "")
	if err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}
	success(c, links)
}

// GetKnowledgeGraph 获取知识图谱数据（节点 + 边）
func (h *NoteHandler) GetKnowledgeGraph(c *gin.Context) {
	graph, err := h.svc.GetKnowledgeGraph()
	if err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}
	success(c, graph)
}

// ─────────────── 标签管理 ───────────────

// GetTagUsage 获取标签及使用次数
func (h *NoteHandler) GetTagUsage(c *gin.Context) {
	usage, err := h.svc.GetTagUsage()
	if err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}
	success(c, usage)
}

// RenameTag 重命名标签
func (h *NoteHandler) RenameTag(c *gin.Context) {
	var req struct {
		OldName string `json:"old_name" binding:"required"`
		NewName string `json:"new_name" binding:"required"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		fail(c, http.StatusBadRequest, "请求参数错误")
		return
	}
	changed, err := h.svc.RenameTag(req.OldName, req.NewName)
	if err != nil {
		fail(c, http.StatusBadRequest, err.Error())
		return
	}
	success(c, gin.H{"changed": changed})
}

// MergeTag 合并标签（from → to）
func (h *NoteHandler) MergeTag(c *gin.Context) {
	var req struct {
		From string `json:"from" binding:"required"`
		To   string `json:"to" binding:"required"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		fail(c, http.StatusBadRequest, "请求参数错误")
		return
	}
	changed, err := h.svc.MergeTag(req.From, req.To)
	if err != nil {
		fail(c, http.StatusBadRequest, err.Error())
		return
	}
	success(c, gin.H{"changed": changed})
}

// DeleteTag 删除标签（从所有笔记中移除）
func (h *NoteHandler) DeleteTag(c *gin.Context) {
	var req struct {
		Name string `json:"name" binding:"required"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		fail(c, http.StatusBadRequest, "请求参数错误")
		return
	}
	changed, err := h.svc.DeleteTag(req.Name)
	if err != nil {
		fail(c, http.StatusBadRequest, err.Error())
		return
	}
	success(c, gin.H{"changed": changed})
}