package api

import (
	"context"
	"fmt"
	"html/template"
	"log"
	"net/http"
	"path/filepath"
	"sync"
	"time"

	"sprintpadawan/lib"
)

type contextKey string

const userKey contextKey = "user"

type sseClient struct {
	ch     chan string
	userID int
}

var (
	roomClients = make(map[int][]*sseClient)
	clientsMu   sync.Mutex
)

var templates *template.Template

// ==================== HELPERS ====================

func addSSEClient(roomID, userID int, ch chan string) {
	clientsMu.Lock()
	defer clientsMu.Unlock()
	roomClients[roomID] = append(roomClients[roomID], &sseClient{ch: ch, userID: userID})
}

func removeSSEClient(roomID int, ch chan string) {
	clientsMu.Lock()
	defer clientsMu.Unlock()
	clients := roomClients[roomID]
	for i, c := range clients {
		if c.ch == ch {
			roomClients[roomID] = append(clients[:i], clients[i+1:]...)
			break
		}
	}
	if len(roomClients[roomID]) == 0 {
		delete(roomClients, roomID)
	}
}

func broadcast(roomID int, event string) {
	clientsMu.Lock()
	defer clientsMu.Unlock()
	alive := roomClients[roomID][:0]
	for _, c := range roomClients[roomID] {
		select {
		case c.ch <- event:
			alive = append(alive, c)
		default:
			// drop dead client
		}
	}
	roomClients[roomID] = alive
}

func GetConnectedUserIDs(roomID int) []int {
	clientsMu.Lock()
	defer clientsMu.Unlock()
	seen := make(map[int]bool)
	var ids []int
	for _, c := range roomClients[roomID] {
		if !seen[c.userID] {
			seen[c.userID] = true
			ids = append(ids, c.userID)
		}
	}
	return ids
}

func scaleToOptions(scale string) []string {
	switch scale {
	case "fibonacci":
		return []string{"1", "2", "3", "5", "8", "13", "21", "?"}
	case "tshirt":
		return []string{"XS", "S", "M", "L", "XL", "XXL", "?"}
	case "linear":
		return []string{"1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "?"}
	default:
		return []string{"1", "2", "3", "5", "8", "13", "21", "?"}
	}
}

func getRoomID(r *http.Request) int {
	return getPathInt(r, "id")
}

func getPathInt(r *http.Request, key string) int {
	var id int
	fmt.Sscanf(r.PathValue(key), "%d", &id)
	return id
}

type MemberView struct {
	Username string
	HasVoted bool
	ID       int
}

type RoomData struct {
	*lib.Room
	User       *lib.User
	Members    []MemberView
	Stories    []lib.Story
	IsOwner    bool
	UserVotes  map[int]string
	StoryVotes map[int][]lib.VoteView
}

// Builds data used by both full page and all partials
func buildRoomData(room *lib.Room, user *lib.User) RoomData {
	members, _ := lib.GetRoomMembers(room.ID)
	stories, _ := lib.GetStoriesForRoom(room.ID)
	connectedIDs := GetConnectedUserIDs(room.ID)
	connectedMap := make(map[int]bool)
	for _, cid := range connectedIDs {
		connectedMap[cid] = true
	}
	connectedMap[user.ID] = true

	var activeVotes []lib.Vote
	if room.ActiveStoryID != nil {
		activeVotes, _ = lib.GetVotesForStory(*room.ActiveStoryID)
	}

	var memberViews []MemberView
	for _, m := range members {
		if !connectedMap[m.ID] {
			continue
		}
		hasVoted := false
		for _, v := range activeVotes {
			if v.UserID == m.ID {
				hasVoted = true
				break
			}
		}
		memberViews = append(memberViews, MemberView{
			Username: m.Username,
			HasVoted: hasVoted,
			ID:       m.ID,
		})
	}

	userVotes := make(map[int]string)
	storyVotes := make(map[int][]lib.VoteView)
	for _, s := range stories {
		votes, _ := lib.GetVotesForStory(s.ID)
		for _, v := range votes {
			if v.UserID == user.ID {
				userVotes[s.ID] = v.Value
			}
		}
		if s.Voted {
			vv, _ := lib.GetVotesWithUsernames(s.ID)
			storyVotes[s.ID] = vv
		}
	}

	return RoomData{
		Room:       room,
		User:       user,
		Members:    memberViews,
		Stories:    stories,
		IsOwner:    room.OwnerID == user.ID,
		UserVotes:  userVotes,
		StoryVotes: storyVotes,
	}
}

func init() {
	templates = template.Must(template.New("").Funcs(template.FuncMap{
		"scaleToOptions": scaleToOptions,
		"derefInt": func(i *int) int {
			if i == nil {
				return 0
			}
			return *i
		},
		"slice": func(s string, start, end int) string {
			if len(s) == 0 {
				return ""
			}
			if start < 0 {
				start = 0
			}
			if end > len(s) || end <= 0 {
				end = len(s)
			}
			if start > end {
				return ""
			}
			return s[start:end]
		},
		"dict": func(values ...interface{}) (map[string]interface{}, error) {
			if len(values)%2 != 0 {
				return nil, fmt.Errorf("odd number of arguments to dict")
			}
			d := make(map[string]interface{})
			for i := 0; i < len(values); i += 2 {
				key, ok := values[i].(string)
				if !ok {
					return nil, fmt.Errorf("dict keys must be strings")
				}
				d[key] = values[i+1]
			}
			return d, nil
		},
	}).ParseGlob(filepath.Join("templates", "*.html")))
}

func SetupRoutes(mux *http.ServeMux) {
	mux.HandleFunc("/login", handleLogin)
	mux.HandleFunc("/register", handleRegister)
	mux.HandleFunc("/logout", handleLogout)

	mux.HandleFunc("/", requireAuth(handleIndex))
	mux.HandleFunc("/rooms/new", requireAuth(handleNewRoom))
	mux.HandleFunc("/rooms/create", requireAuth(handleCreateRoom))
	mux.HandleFunc("/rooms/join", requireAuth(handleJoinRoom))
	mux.HandleFunc("/rooms/{id}", requireAuth(handleRoom))

	// HTMX partials
	mux.HandleFunc("/rooms/{id}/partial/stories", requireAuth(handlePartialStories))
	mux.HandleFunc("/rooms/{id}/partial/members", requireAuth(handlePartialMembers))
	mux.HandleFunc("/rooms/{id}/partial/vote-area", requireAuth(handlePartialVoteArea))

	// Actions
	mux.HandleFunc("/rooms/{id}/stories/new", requireAuth(handleNewStoryForm))
	mux.HandleFunc("/rooms/{id}/stories", requireAuth(handleAddStory))
	mux.HandleFunc("/rooms/{id}/active", requireAuth(handleSetActiveStory))
	mux.HandleFunc("/rooms/{id}/vote", requireAuth(handleVote))
	mux.HandleFunc("/rooms/{id}/reveal", requireAuth(handleReveal))
	mux.HandleFunc("/rooms/{id}/stories/{story_id}/edit", requireAuth(handleEditStoryForm))
	mux.HandleFunc("/rooms/{id}/stories/{story_id}/rename", requireAuth(handleRenameStory))
	mux.HandleFunc("/rooms/{id}/stories/{story_id}/delete", requireAuth(handleDeleteStory))
	mux.HandleFunc("/rooms/{id}/stories/{story_id}/unreveal", requireAuth(handleUnrevealStory))
	mux.HandleFunc("/sse/{room_id}", requireAuth(handleSSE))
}

func isHTMX(r *http.Request) bool {
	return r.Header.Get("HX-Request") == "true"
}

func renderTemplate(w http.ResponseWriter, name string, data interface{}) {
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	if err := templates.ExecuteTemplate(w, name, data); err != nil {
		log.Printf("template error (%s): %v", name, err)
		http.Error(w, "internal server error", http.StatusInternalServerError)
	}
}

func renderRoomStories(w http.ResponseWriter, roomID int, user *lib.User) {
	room, err := lib.GetRoomByID(roomID)
	if err != nil {
		http.Error(w, "room not found", http.StatusNotFound)
		return
	}

	renderTemplate(w, "stories-panel", buildRoomData(room, user))
}

func renderRoomMembers(w http.ResponseWriter, roomID int, user *lib.User) {
	room, err := lib.GetRoomByID(roomID)
	if err != nil {
		http.Error(w, "room not found", http.StatusNotFound)
		return
	}

	renderTemplate(w, "members-panel", buildRoomData(room, user))
}

func requireAuth(next http.HandlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		cookie, err := r.Cookie("session_token")
		if err != nil {
			http.Redirect(w, r, "/login", http.StatusSeeOther)
			return
		}
		user, err := lib.GetUserFromSession(cookie.Value)
		if err != nil || user == nil {
			http.Redirect(w, r, "/login", http.StatusSeeOther)
			return
		}
		ctx := context.WithValue(r.Context(), userKey, user)
		next.ServeHTTP(w, r.WithContext(ctx))
	}
}

func isLoggedIn(r *http.Request) bool {
	cookie, err := r.Cookie("session_token")
	if err != nil {
		return false
	}
	user, err := lib.GetUserFromSession(cookie.Value)
	return err == nil && user != nil
}

// ==================== AUTH HANDLERS ====================

func handleLogin(w http.ResponseWriter, r *http.Request) {
	if r.Method == http.MethodGet {
		if isLoggedIn(r) {
			http.Redirect(w, r, "/", http.StatusSeeOther)
			return
		}
		templates.ExecuteTemplate(w, "login.html", nil)
		return
	}

	username := r.FormValue("username")
	password := r.FormValue("password")

	user, err := lib.GetUserByUsername(username)
	if err != nil || !lib.CheckPasswordHash(password, user.PasswordHash) {
		templates.ExecuteTemplate(w, "login.html", map[string]string{"Error": "Invalid credentials"})
		return
	}

	sessionID, _ := lib.CreateSession(user.ID)
	http.SetCookie(w, &http.Cookie{
		Name:     "session_token",
		Value:    sessionID,
		Expires:  time.Now().Add(24 * time.Hour),
		HttpOnly: true,
		Path:     "/",
	})

	http.Redirect(w, r, "/", http.StatusSeeOther)
}

func handleRegister(w http.ResponseWriter, r *http.Request) {
	if r.Method == http.MethodGet {
		if isLoggedIn(r) {
			http.Redirect(w, r, "/", http.StatusSeeOther)
			return
		}
		templates.ExecuteTemplate(w, "register.html", nil)
		return
	}

	username := r.FormValue("username")
	password := r.FormValue("password")
	confirm := r.FormValue("confirm_password")

	if password != confirm {
		templates.ExecuteTemplate(w, "register.html", map[string]string{"Error": "Passwords do not match"})
		return
	}

	err := lib.CreateUser(username, password)
	if err != nil {
		templates.ExecuteTemplate(w, "register.html", map[string]string{"Error": "Username taken"})
		return
	}

	http.Redirect(w, r, "/login", http.StatusSeeOther)
}

func handleLogout(w http.ResponseWriter, r *http.Request) {
	cookie, err := r.Cookie("session_token")
	if err == nil {
		lib.DeleteSession(cookie.Value)
	}
	http.SetCookie(w, &http.Cookie{
		Name:    "session_token",
		Value:   "",
		Expires: time.Now().Add(-1 * time.Hour),
		Path:    "/",
	})
	http.Redirect(w, r, "/login", http.StatusSeeOther)
}

// ==================== DASHBOARD ====================

func handleIndex(w http.ResponseWriter, r *http.Request) {
	if r.URL.Path != "/" {
		http.NotFound(w, r)
		return
	}
	user := r.Context().Value(userKey).(*lib.User)
	rooms, _ := lib.GetRoomsForUser(user.ID)
	w.Header().Set("Content-Type", "text/html; charset=utf-8")

	type RoomView struct {
		ID          int
		Name        string
		Code        string
		Scale       string
		IsOwner     bool
		MemberCount int
	}

	data := struct {
		*lib.User
		Rooms []RoomView
	}{
		User: user,
	}

	for _, room := range rooms {
		members, _ := lib.GetRoomMembers(room.ID)
		data.Rooms = append(data.Rooms, RoomView{
			ID:          room.ID,
			Name:        room.Name,
			Code:        room.Code,
			Scale:       room.Scale,
			IsOwner:     room.OwnerID == user.ID,
			MemberCount: len(members),
		})
	}

	if err := templates.ExecuteTemplate(w, "index.html", data); err != nil {
		log.Printf("template error: %v", err)
		http.Error(w, "internal server error", http.StatusInternalServerError)
	}
}

// ==================== ROOM CREATION / JOIN ====================

func handleNewRoom(w http.ResponseWriter, r *http.Request) {
	if err := templates.ExecuteTemplate(w, "room_form.html", nil); err != nil {
		log.Printf("template error: %v", err)
	}
}

func handleCreateRoom(w http.ResponseWriter, r *http.Request) {
	user := r.Context().Value(userKey).(*lib.User)
	name := r.FormValue("name")
	scale := r.FormValue("scale")
	room, err := lib.CreateRoom(name, user.ID, scale)
	if err != nil {
		log.Printf("create room error: %v", err)
		http.Error(w, "failed to create room", http.StatusInternalServerError)
		return
	}
	http.Redirect(w, r, fmt.Sprintf("/rooms/%d", room.ID), http.StatusSeeOther)
}

func handleJoinRoom(w http.ResponseWriter, r *http.Request) {
	user := r.Context().Value(userKey).(*lib.User)
	code := r.FormValue("code")
	room, err := lib.GetRoomByCode(code)
	if err != nil {
		http.Error(w, "room not found", http.StatusNotFound)
		return
	}
	lib.AddUserToRoom(room.ID, user.ID)
	http.Redirect(w, r, fmt.Sprintf("/rooms/%d", room.ID), http.StatusSeeOther)
}

// ==================== MAIN ROOM & PARTIALS ====================

func handleRoom(w http.ResponseWriter, r *http.Request) {
	roomID := getRoomID(r)
	user := r.Context().Value(userKey).(*lib.User)
	room, err := lib.GetRoomByID(roomID)
	if err != nil {
		http.NotFound(w, r)
		return
	}
	lib.AddUserToRoom(room.ID, user.ID)

	data := buildRoomData(room, user)
	renderTemplate(w, "room.html", data)
}

func handlePartialStories(w http.ResponseWriter, r *http.Request) {
	roomID := getRoomID(r)
	user := r.Context().Value(userKey).(*lib.User)
	renderRoomStories(w, roomID, user)
}

func handlePartialMembers(w http.ResponseWriter, r *http.Request) {
	roomID := getRoomID(r)
	user := r.Context().Value(userKey).(*lib.User)
	renderRoomMembers(w, roomID, user)
}

func handlePartialVoteArea(w http.ResponseWriter, r *http.Request) {
	roomID := getRoomID(r)
	user := r.Context().Value(userKey).(*lib.User)
	room, err := lib.GetRoomByID(roomID)
	if err != nil {
		http.Error(w, "room not found", http.StatusNotFound)
		return
	}
	if room.ActiveStoryID == nil {
		w.WriteHeader(http.StatusNoContent)
		return
	}

	story, err := lib.GetStoryByID(*room.ActiveStoryID)
	if err != nil {
		http.Error(w, "story not found", http.StatusNotFound)
		return
	}

	data := struct {
		RoomData RoomData
		Story    lib.Story
	}{
		RoomData: buildRoomData(room, user),
		Story:    *story,
	}
	renderTemplate(w, "vote-area", data)
}

// ==================== STORY & VOTING ACTIONS ====================

func handleNewStoryForm(w http.ResponseWriter, r *http.Request) {
	roomID := getRoomID(r)
	room, _ := lib.GetRoomByID(roomID)
	renderTemplate(w, "story_form.html", room)
}

func handleAddStory(w http.ResponseWriter, r *http.Request) {
	id := getRoomID(r)
	user := r.Context().Value(userKey).(*lib.User)
	title := r.FormValue("title")
	_, err := lib.CreateStory(id, title)
	if err != nil {
		log.Printf("create story error: %v", err)
		http.Error(w, "failed to create story", http.StatusInternalServerError)
		return
	}
	broadcast(id, "stories")
	if isHTMX(r) {
		renderRoomStories(w, id, user)
		return
	}
	http.Redirect(w, r, fmt.Sprintf("/rooms/%d", id), http.StatusSeeOther)
}

func handleSetActiveStory(w http.ResponseWriter, r *http.Request) {
	id := getRoomID(r)
	user := r.Context().Value(userKey).(*lib.User)
	var sid int
	fmt.Sscanf(r.FormValue("story_id"), "%d", &sid)

	room, _ := lib.GetRoomByID(id)
	if room.ActiveStoryID != nil {
		lib.UnrevealStory(*room.ActiveStoryID)
		lib.ClearVotesForStory(*room.ActiveStoryID)
	}
	lib.UnrevealStory(sid)
	lib.ClearVotesForStory(sid)
	lib.SetActiveStory(id, sid)

	broadcast(id, "stories")
	broadcast(id, "members")
	if isHTMX(r) {
		renderRoomStories(w, id, user)
		return
	}
	http.Redirect(w, r, fmt.Sprintf("/rooms/%d", id), http.StatusSeeOther)
}

func handleVote(w http.ResponseWriter, r *http.Request) {
	id := getRoomID(r)
	user := r.Context().Value(userKey).(*lib.User)
	value := r.FormValue("value")
	var sid int
	fmt.Sscanf(r.FormValue("story_id"), "%d", &sid)

	lib.VoteOnStory(sid, user.ID, value)
	broadcast(id, "members")
	if story, err := lib.GetStoryByID(sid); err == nil && story.Voted {
		broadcast(id, "stories")
	}

	if r.Header.Get("HX-Request") == "true" {
		room, _ := lib.GetRoomByID(id)
		story, _ := lib.GetStoryByID(sid)
		tmplData := struct {
			RoomID   int
			Story    lib.Story
			Scale    string
			UserVote string
		}{
			RoomID:   id,
			Story:    *story,
			Scale:    room.Scale,
			UserVote: value,
		}
		renderTemplate(w, "vote_form.html", tmplData)
		return
	}

	http.Redirect(w, r, fmt.Sprintf("/rooms/%d", id), http.StatusSeeOther)
}

func handleReveal(w http.ResponseWriter, r *http.Request) {
	id := getRoomID(r)
	user := r.Context().Value(userKey).(*lib.User)
	var sid int
	fmt.Sscanf(r.FormValue("story_id"), "%d", &sid)
	lib.RevealVotes(sid)
	broadcast(id, "stories")
	if isHTMX(r) {
		renderRoomStories(w, id, user)
		return
	}
	http.Redirect(w, r, fmt.Sprintf("/rooms/%d", id), http.StatusSeeOther)
}

func handleUnrevealStory(w http.ResponseWriter, r *http.Request) {
	id := getRoomID(r)
	user := r.Context().Value(userKey).(*lib.User)
	var sid int
	fmt.Sscanf(r.PathValue("story_id"), "%d", &sid)
	lib.UnrevealStory(sid)
	broadcast(id, "stories")
	if isHTMX(r) {
		renderRoomStories(w, id, user)
		return
	}
	http.Redirect(w, r, fmt.Sprintf("/rooms/%d", id), http.StatusSeeOther)
}

func handleEditStoryForm(w http.ResponseWriter, r *http.Request) {
	roomID := getRoomID(r)
	var storyID int
	fmt.Sscanf(r.PathValue("story_id"), "%d", &storyID)
	story, _ := lib.GetStoryByID(storyID)
	data := struct {
		RoomID int
		Story  lib.Story
	}{
		RoomID: roomID,
		Story:  *story,
	}
	renderTemplate(w, "story_edit.html", data)
}

func handleRenameStory(w http.ResponseWriter, r *http.Request) {
	id := getRoomID(r)
	user := r.Context().Value(userKey).(*lib.User)
	var sid int
	fmt.Sscanf(r.PathValue("story_id"), "%d", &sid)
	title := r.FormValue("title")
	lib.RenameStory(sid, title)
	broadcast(id, "stories")
	if isHTMX(r) {
		renderRoomStories(w, id, user)
		return
	}
	http.Redirect(w, r, fmt.Sprintf("/rooms/%d", id), http.StatusSeeOther)
}

func handleDeleteStory(w http.ResponseWriter, r *http.Request) {
	id := getRoomID(r)
	user := r.Context().Value(userKey).(*lib.User)
	var sid int
	fmt.Sscanf(r.PathValue("story_id"), "%d", &sid)
	lib.DeleteStory(sid)
	broadcast(id, "stories")
	if isHTMX(r) {
		renderRoomStories(w, id, user)
		return
	}
	http.Redirect(w, r, fmt.Sprintf("/rooms/%d", id), http.StatusSeeOther)
}

// ==================== SSE ====================

func handleSSE(w http.ResponseWriter, r *http.Request) {
	roomID := getPathInt(r, "room_id")
	user, ok := r.Context().Value(userKey).(*lib.User)
	if !ok {
		http.Error(w, "Unauthorized", http.StatusUnauthorized)
		return
	}

	ch := make(chan string, 10)
	addSSEClient(roomID, user.ID, ch)
	broadcast(roomID, "members") // notify others of new connection

	w.Header().Set("Content-Type", "text/event-stream")
	w.Header().Set("Cache-Control", "no-cache")
	w.Header().Set("Connection", "keep-alive")
	w.Header().Set("X-Accel-Buffering", "no")

	flusher, ok := w.(http.Flusher)
	if !ok {
		http.Error(w, "streaming unsupported", http.StatusInternalServerError)
		return
	}
	notify := r.Context().Done()
	heartbeat := time.NewTicker(25 * time.Second)
	defer heartbeat.Stop()

	fmt.Fprint(w, ": connected\n\n")
	flusher.Flush()

	for {
		select {
		case <-notify:
			removeSSEClient(roomID, ch)
			broadcast(roomID, "members")
			return
		case <-heartbeat.C:
			fmt.Fprint(w, ": keep-alive\n\n")
			flusher.Flush()
		case event := <-ch:
			fmt.Fprintf(w, "event: %s\ndata: true\n\n", event)
			flusher.Flush()
		}
	}
}