package api

import (
	"context"
	"errors"
	"net/http"
	"strconv"
	"time"

	"github.com/gin-gonic/gin"

	"ws_usernode/internal/config"
	"ws_usernode/internal/model"
	"ws_usernode/internal/service"
)

// UserHandler 外部用户接口（列表/详情/创建/更新/禁用/启用/延期/删除，admin）。
type UserHandler struct {
	svc *service.UserService
	cfg *config.Config
	h   *Handler // 访问审计 helper
}

// UserCreateRequest 管理员创建外部用户请求。
type UserCreateRequest struct {
	Username   string `json:"username" binding:"required"` // 不含 ext_ 前缀
	Email      string `json:"email" binding:"required"`
	Supervisor string `json:"supervisor"`
	Purpose    string `json:"purpose"`
	TTLDays    int64  `json:"ttl_days"` // 0 表示用配置默认
}

// Create 管理员创建外部用户（自动建系统账号）。
func (h *UserHandler) Create(c *gin.Context) {
	var req UserCreateRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		fail(c, http.StatusBadRequest, "请求参数不合法: "+err.Error())
		return
	}
	createdBy := uint(0)
	if sess := sessionFrom(c); sess != nil {
		createdBy = sess.RefID
	}
	u, err := h.svc.Create(c.Request.Context(), req.Username, req.Email, req.Supervisor, req.Purpose,
		time.Duration(req.TTLDays)*24*time.Hour, createdBy)
	if err != nil {
		h.h.audit(c, "user.create", "user", "", map[string]any{"username": req.Username, "err": err.Error()}, model.ResultFailed)
		switch {
		case errors.Is(err, service.ErrUserExists):
			fail(c, http.StatusConflict, err.Error())
		default:
			fail(c, http.StatusBadRequest, err.Error())
		}
		return
	}
	h.h.audit(c, "user.create", "user", strconv.FormatUint(uint64(u.ID), 10), map[string]any{"username": u.Username}, model.ResultSuccess)
	ok(c, gin.H{"id": u.ID, "username": u.Username, "status": u.Status, "expire_at": u.ExpireAt})
}

// List 用户列表（分页/筛选：status、supervisor）。
func (h *UserHandler) List(c *gin.Context) {
	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))
	users, total, err := h.svc.List(c.Request.Context(), service.UserFilter{
		Status:     c.Query("status"),
		Supervisor: c.Query("supervisor"),
		Page:       page,
		PageSize:   pageSize,
	})
	if err != nil {
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}
	ok(c, gin.H{"total": total, "items": users})
}

// Get 用户详情。
func (h *UserHandler) Get(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的用户 ID")
		return
	}
	u, err := h.svc.GetByID(c.Request.Context(), uint(id))
	if err != nil {
		fail(c, http.StatusNotFound, err.Error())
		return
	}
	ok(c, u)
}

// UserUpdateRequest 更新外部用户信息（仅更新提供的字段；邮箱仅管理员可改）。
type UserUpdateRequest struct {
	Email      *string `json:"email"`
	Supervisor *string `json:"supervisor"`
	Purpose    *string `json:"purpose"`
}

// Update PATCH /users/:id。
func (h *UserHandler) Update(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的用户 ID")
		return
	}
	var req UserUpdateRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		fail(c, http.StatusBadRequest, "请求参数不合法: "+err.Error())
		return
	}
	u, err := h.svc.Update(c.Request.Context(), uint(id), req.Email, req.Supervisor, req.Purpose)
	if err != nil {
		h.h.audit(c, "user.update", "user", c.Param("id"), map[string]any{"err": err.Error()}, model.ResultFailed)
		if errors.Is(err, service.ErrUserNotFound) {
			fail(c, http.StatusNotFound, err.Error())
			return
		}
		fail(c, http.StatusBadRequest, err.Error())
		return
	}
	h.h.audit(c, "user.update", "user", c.Param("id"), map[string]any{"email": req.Email, "supervisor": req.Supervisor, "purpose": req.Purpose}, model.ResultSuccess)
	ok(c, u)
}

// Disable POST /users/:id/disable —— 禁用（清空 authorized_keys，SSH 立即失效）。
func (h *UserHandler) Disable(c *gin.Context) {
	h.setStatus(c, "user.disable", model.UserStatusDisabled, h.svc.Disable)
}

// Enable POST /users/:id/enable —— 启用（按 DB 密钥状态恢复）。
func (h *UserHandler) Enable(c *gin.Context) {
	h.setStatus(c, "user.enable", model.UserStatusActive, h.svc.Enable)
}

// setStatus 复用禁用/启用的公共流程（解析 ID、调 service、审计）。
func (h *UserHandler) setStatus(c *gin.Context, action, wantStatus string, fn func(ctx context.Context, id uint) error) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的用户 ID")
		return
	}
	if err := fn(c, uint(id)); err != nil {
		h.h.audit(c, action, "user", c.Param("id"), map[string]any{"err": err.Error()}, model.ResultFailed)
		switch {
		case errors.Is(err, service.ErrUserNotFound):
			fail(c, http.StatusNotFound, err.Error())
		case errors.Is(err, service.ErrUserExpired):
			fail(c, http.StatusConflict, err.Error())
		case errors.Is(err, service.ErrSystemAccountMissing):
			fail(c, http.StatusConflict, err.Error())
		default:
			fail(c, http.StatusInternalServerError, err.Error())
		}
		return
	}
	h.h.audit(c, action, "user", c.Param("id"), map[string]any{"status": wantStatus}, model.ResultSuccess)
	ok(c, gin.H{"status": wantStatus})
}

// ExtendRequest 延期请求。
type ExtendRequest struct {
	Days int `json:"days"` // 0 表示用配置默认（90 天）
}

// Extend POST /users/:id/extend —— 延长有效期；已过期用户在回收期内可恢复。
func (h *UserHandler) Extend(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的用户 ID")
		return
	}
	var req ExtendRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		fail(c, http.StatusBadRequest, "请求参数不合法: "+err.Error())
		return
	}
	u, err := h.svc.GetByID(c.Request.Context(), uint(id))
	if err != nil {
		fail(c, http.StatusNotFound, err.Error())
		return
	}
	newExpire, err := h.svc.Extend(c.Request.Context(), uint(id), req.Days)
	if err != nil {
		h.h.audit(c, "user.extend", "user", c.Param("id"), map[string]any{"days": req.Days, "err": err.Error()}, model.ResultFailed)
		fail(c, http.StatusInternalServerError, err.Error())
		return
	}
	h.h.audit(c, "user.extend", "user", c.Param("id"), map[string]any{"days": req.Days, "old_status": u.Status}, model.ResultSuccess)
	ok(c, gin.H{"expire_at": newExpire.UTC()})
}

// Delete DELETE /users/:id —— 删除并回收（系统账号 + 家目录 + 密钥，保留审计）。
func (h *UserHandler) Delete(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		fail(c, http.StatusBadRequest, "无效的用户 ID")
		return
	}
	if err := h.svc.Delete(c.Request.Context(), uint(id)); err != nil {
		h.h.audit(c, "user.delete", "user", c.Param("id"), map[string]any{"err": err.Error()}, model.ResultFailed)
		switch {
		case errors.Is(err, service.ErrUserNotFound):
			fail(c, http.StatusNotFound, err.Error())
		default:
			fail(c, http.StatusInternalServerError, err.Error())
		}
		return
	}
	h.h.audit(c, "user.delete", "user", c.Param("id"), nil, model.ResultSuccess)
	ok(c, gin.H{"status": "deleted"})
}