package web

import (
	"fmt"
	"io"
	"log"
	"mime"
	"net/http"
	"sort"
	"strings"

	"github.com/bouncepaw/mycorrhiza/cfg"
	"github.com/bouncepaw/mycorrhiza/user"
	"github.com/bouncepaw/mycorrhiza/util"
	"github.com/bouncepaw/mycorrhiza/views"
)

// initAdmin sets up /admin routes if auth is used. Call it after you have decided if you want to use auth.
func initAdmin() {
	if cfg.UseAuth {
		http.HandleFunc("/admin/", handlerAdmin)
		http.HandleFunc("/admin/shutdown/", handlerAdminShutdown)
		http.HandleFunc("/admin/reindex-users/", handlerAdminReindexUsers)

		http.HandleFunc("/admin/users/", handlerAdminUsers)
		http.HandleFunc("/admin/user/new", handlerAdminUserNew)
	}
}

// handlerAdmin provides the admin panel.
func handlerAdmin(w http.ResponseWriter, rq *http.Request) {
	util.PrepareRq(rq)
	if user.CanProceed(rq, "admin") {
		w.Header().Set("Content-Type", "text/html;charset=utf-8")
		w.WriteHeader(http.StatusOK)
		_, err := io.WriteString(w, views.BaseHTML("Admin panel", views.AdminPanelHTML(), user.FromRequest(rq)))
		if err != nil {
			log.Println(err)
		}
	}
}

// handlerAdminShutdown kills the wiki.
func handlerAdminShutdown(w http.ResponseWriter, rq *http.Request) {
	util.PrepareRq(rq)
	if user.CanProceed(rq, "admin/shutdown") && rq.Method == "POST" {
		log.Fatal("An admin commanded the wiki to shutdown")
	}
}

// handlerAdminReindexUsers reinitialises the user system.
func handlerAdminReindexUsers(w http.ResponseWriter, rq *http.Request) {
	util.PrepareRq(rq)
	if user.CanProceed(rq, "admin") && rq.Method == "POST" {
		user.ReadUsersFromFilesystem()
		redirectTo := rq.Referer()
		if redirectTo == "" {
			redirectTo = "/hypha/" + cfg.UserHypha
		}
		http.Redirect(w, rq, redirectTo, http.StatusSeeOther)
	}
}

func handlerAdminUsers(w http.ResponseWriter, r *http.Request) {
	util.PrepareRq(r)
	if user.CanProceed(r, "admin") {
		path := strings.TrimPrefix(r.URL.Path, "/admin/users")
		parts := strings.Split(path, "/")[1:]

		// Users dashboard
		if len(parts) == 0 {
			// Get a sorted list of users
			var userList []*user.User
			for u := range user.YieldUsers() {
				userList = append(userList, u)
			}

			sort.Slice(userList, func(i, j int) bool {
				less := userList[i].RegisteredAt.Before(userList[j].RegisteredAt)
				return less
			})

			html := views.AdminUsersPanelHTML(userList)
			html = views.BaseHTML("Manage users", html, user.FromRequest(r))

			w.Header().Set("Content-Type", mime.TypeByExtension(".html"))
			if _, err := io.WriteString(w, html); err != nil {
				log.Println(err)
			}
			return
		}

		if len(parts) != 2 {
			util.HTTP404Page(w, "404 page not found")
			return
		}

		u := user.UserByName(parts[0])
		if u == nil {
			util.HTTP404Page(w, "404 page not found")
			return
		}

		switch parts[1] {
		case "edit":
			f := util.FormDataFromRequest(r, []string{"group"})

			if r.Method == http.MethodPost {
				oldGroup := u.Group
				newGroup := f.Get("group")

				if user.ValidGroup(newGroup) {
					u.Group = newGroup
					if err := user.SaveUserDatabase(); err != nil {
						u.Group = oldGroup
						log.Println(err)
						f = f.WithError(err)
					} else {
						http.Redirect(w, r, "/admin/users/", http.StatusSeeOther)
						return
					}
				} else {
					f = f.WithError(fmt.Errorf("invalid group \"%s\"", newGroup))
				}
			}

			f.Put("group", u.Group)

			html := views.AdminUserEditHTML(u, f)
			html = views.BaseHTML(fmt.Sprintf("User %s", u.Name), html, user.FromRequest(r))

			if f.HasError() {
				w.WriteHeader(http.StatusBadRequest)
			}
			w.Header().Set("Content-Type", mime.TypeByExtension(".html"))
			io.WriteString(w, html)
			return
		case "delete":
			f := util.NewFormData()

			if r.Method == http.MethodPost {
				f = f.WithError(user.DeleteUser(u.Name))
				if !f.HasError() {
					http.Redirect(w, r, "/admin/users/", http.StatusSeeOther)
				} else {
					log.Println(f.Error())
				}
			}

			html := views.AdminUserDeleteHTML(u, util.NewFormData())
			html = views.BaseHTML(fmt.Sprintf("User %s", u.Name), html, user.FromRequest(r))

			if f.HasError() {
				w.WriteHeader(http.StatusBadRequest)
			}
			w.Header().Set("Content-Type", mime.TypeByExtension(".html"))
			io.WriteString(w, html)
			return
		}

		util.HTTP404Page(w, "404 page not found")
	}
}

func handlerAdminUserNew(w http.ResponseWriter, r *http.Request) {
	util.PrepareRq(r)
	if user.CanProceed(r, "admin") {
		if r.Method == http.MethodGet {
			// New user form
			html := views.AdminUserNewHTML(util.NewFormData())
			html = views.BaseHTML("New user", html, user.FromRequest(r))

			w.Header().Set("Content-Type", mime.TypeByExtension(".html"))
			io.WriteString(w, html)
			return
		} else if r.Method == http.MethodPost {
			// Create a user
			f := util.FormDataFromRequest(r, []string{"name", "password", "group"})

			err := user.Register(f.Get("name"), f.Get("password"), f.Get("group"), true)

			if err != nil {
				html := views.AdminUserNewHTML(f.WithError(err))
				html = views.BaseHTML("New user", html, user.FromRequest(r))

				w.WriteHeader(http.StatusBadRequest)
				w.Header().Set("Content-Type", mime.TypeByExtension(".html"))
				io.WriteString(w, html)
			} else {
				http.Redirect(w, r, "/admin/users/", http.StatusSeeOther)
			}
			return
		}
	}

	util.HTTP404Page(w, "404 page not found")
}