package internal

import (
	"encoding/json"
	"io/ioutil"
	"log"
	"net/http"
	"strconv"
	"strings"

	"github.com/gorilla/mux"

	"github.com/signaller-matrix/signaller/internal/models"
	"github.com/signaller-matrix/signaller/internal/models/capabilities"
	"github.com/signaller-matrix/signaller/internal/models/common"
	"github.com/signaller-matrix/signaller/internal/models/devices"
	"github.com/signaller-matrix/signaller/internal/models/filter"
	"github.com/signaller-matrix/signaller/internal/models/joinedrooms"
	"github.com/signaller-matrix/signaller/internal/models/listroom"
	"github.com/signaller-matrix/signaller/internal/models/login"
	"github.com/signaller-matrix/signaller/internal/models/password"
	"github.com/signaller-matrix/signaller/internal/models/publicrooms"
	"github.com/signaller-matrix/signaller/internal/models/register"
	"github.com/signaller-matrix/signaller/internal/models/registeravailable"
	"github.com/signaller-matrix/signaller/internal/models/roomalias"
	mSync "github.com/signaller-matrix/signaller/internal/models/sync"
	"github.com/signaller-matrix/signaller/internal/models/versions"
	"github.com/signaller-matrix/signaller/internal/models/whoami"
)

func RootHandler(w http.ResponseWriter, r *http.Request) {
	log.Println(r.RequestURI)
}

// https://models.org/docs/spec/client_server/latest#get-models-client-versions
func VersionHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		errorResponse(w, models.M_UNKNOWN, http.StatusBadRequest, "wrong method: "+r.Method)
		return
	}

	response := versions.Reply{Versions: []string{Version}}
	sendJsonResponse(w, http.StatusOK, response)
}

// https://models.org/docs/spec/client_server/latest#login
func LoginHandler(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	// https://models.org/docs/spec/client_server/latest#get-models-client-r0-login
	case "GET":
		{
			response := login.GetReply{
				Flows: []login.Flow{
					login.Flow{Type: common.AuthenticationTypePassword},
				},
			}

			sendJsonResponse(w, http.StatusOK, response)
		}
	// https://models.org/docs/spec/client_server/latest#post-models-client-r0-login
	case "POST":
		{
			var request login.PostRequest
			getRequest(r, &request) // TODO: handle error

			// delete start "@" if presents
			if strings.HasPrefix(request.Identifier.User, "@") {
				request.Identifier.User = strings.TrimPrefix(request.Identifier.User, "@")
			}

			_, token, apiErr := currServer.Backend.Login(request.Identifier.User, request.Password, request.DeviceID)
			if apiErr != nil {
				errorResponse(w, apiErr, http.StatusForbidden, "")
				return
			}

			response := login.PostReply{
				UserID:      request.Identifier.User,
				AccessToken: token,
			}

			sendJsonResponse(w, http.StatusOK, response)
		}
	}
}

// https://matrix.org/docs/spec/client_server/latest#post-matrix-client-r0-rooms-roomid-leave
func leaveRoomHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		errorResponse(w, models.M_UNKNOWN, http.StatusBadRequest, "wrong method: "+r.Method)
		return
	}

	token := getTokenFromResponse(r)

	if token == "" {
		errorResponse(w, models.M_MISSING_TOKEN, http.StatusBadRequest, "")
		return
	}

	user := currServer.Backend.GetUserByToken(token)
	if user == nil {
		errorResponse(w, models.M_UNKNOWN_TOKEN, http.StatusBadRequest, "")
		return
	}

	room := currServer.Backend.GetRoomByID(mux.Vars(r)["roomID"]) // TODO: can ["roomID"] throw panic?
	if room == nil {
		errorResponse(w, models.M_NOT_FOUND, http.StatusBadRequest, "room not found")
		return
	}

	err := user.LeaveRoom(room)
	if err != nil {
		errorResponse(w, err, http.StatusBadRequest, "")
		return
	}

	sendJsonResponse(w, http.StatusOK, struct{}{})
}

// https://models.org/docs/spec/client_server/latest#post-models-client-r0-logout
func LogoutHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		errorResponse(w, models.M_UNKNOWN, http.StatusBadRequest, "wrong method: "+r.Method)
		return
	}

	token := getTokenFromResponse(r)

	if token == "" {
		errorResponse(w, models.M_MISSING_TOKEN, http.StatusBadRequest, "")
		return
	}

	user := currServer.Backend.GetUserByToken(token)
	if user == nil {
		errorResponse(w, models.M_UNKNOWN_TOKEN, http.StatusBadRequest, "")
		return
	}

	user.Logout(token)

	sendJsonResponse(w, http.StatusOK, struct{}{})
}

// https://matrix.org/docs/spec/client_server/latest#post-matrix-client-r0-logout-all
func LogoutAllHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		errorResponse(w, models.M_UNKNOWN, http.StatusBadRequest, "wrong method: "+r.Method)
		return
	}

	token := getTokenFromResponse(r)

	if token == "" {
		errorResponse(w, models.M_MISSING_TOKEN, http.StatusBadRequest, "")
		return
	}

	user := currServer.Backend.GetUserByToken(token)
	if user == nil {
		errorResponse(w, models.M_UNKNOWN_TOKEN, http.StatusBadRequest, "")
		return
	}

	user.LogoutAll()

	sendJsonResponse(w, http.StatusOK, struct{}{})
}

// https://models.org/docs/spec/client_server/latest#post-models-client-r0-register
func RegisterHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		errorResponse(w, models.M_UNKNOWN, http.StatusBadRequest, "wrong method: "+r.Method)
		return
	}

	kind := r.FormValue("kind")
	if kind != "user" {
		errorResponse(w, models.M_UNKNOWN, http.StatusBadRequest, "wrong kind: "+kind)
		return
	}

	var request register.RegisterRequest
	getRequest(r, &request) // TODO: handle error

	_, token, apiErr := currServer.Backend.Register(request.Username, request.Password, request.DeviceID)
	if apiErr != nil {
		errorResponse(w, apiErr, http.StatusBadRequest, "")
		return
	}

	var response register.RegisterResponse
	response.UserID = "@" + request.Username
	response.DeviceID = request.DeviceID
	response.AccessToken = token

	sendJsonResponse(w, http.StatusOK, response)
}

// https://matrix.org/docs/spec/client_server/latest#get-matrix-client-r0-account-whoami
func WhoAmIHandler(w http.ResponseWriter, r *http.Request) {
	token := getTokenFromResponse(r)
	if token == "" {
		errorResponse(w, models.M_MISSING_TOKEN, http.StatusForbidden, "")
		return
	}

	user := currServer.Backend.GetUserByToken(token)
	if user == nil {
		errorResponse(w, models.M_UNKNOWN_TOKEN, http.StatusForbidden, "")
		return
	}

	response := whoami.Response{UserID: user.ID()}

	sendJsonResponse(w, http.StatusOK, response)
}

// https://matrix.org/docs/spec/client_server/latest#get-matrix-client-r0-joined-rooms
func JoinedRoomsHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		errorResponse(w, models.M_UNKNOWN, http.StatusBadRequest, "wrong method: "+r.Method)
		return
	}

	token := getTokenFromResponse(r)
	if token == "" {
		errorResponse(w, models.M_FORBIDDEN, http.StatusForbidden, "")
		return
	}

	user := currServer.Backend.GetUserByToken(token)
	if user == nil {
		errorResponse(w, models.M_UNKNOWN_TOKEN, http.StatusBadRequest, "")
		return
	}

	rooms := user.JoinedRooms()

	var response joinedrooms.Response
	for _, room := range rooms {
		response.JoinedRooms = append(response.JoinedRooms, room.ID())
	}

	sendJsonResponse(w, http.StatusOK, response)
}

// https://matrix.org/docs/spec/client_server/latest#post-matrix-client-r0-account-password
func PasswordHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		errorResponse(w, models.M_UNKNOWN, http.StatusBadRequest, "wrong method: "+r.Method)
		return
	}

	token := getTokenFromResponse(r)
	if token == "" {
		errorResponse(w, models.M_FORBIDDEN, http.StatusForbidden, "")
		return
	}

	user := currServer.Backend.GetUserByToken(token)
	if user == nil {
		errorResponse(w, models.M_UNKNOWN_TOKEN, http.StatusBadRequest, "")
		return
	}

	var request password.Request
	getRequest(r, &request) // TODO: handle error

	user.ChangePassword(request.NewPassword)

	sendJsonResponse(w, http.StatusOK, struct{}{})
}

// https://models.org/docs/spec/client_server/latest#get-models-client-r0-sync
func SyncHandler(w http.ResponseWriter, r *http.Request) {
	var request mSync.SyncRequest
	request.Filter = r.FormValue("filter")

	timeout, err := strconv.Atoi(r.FormValue("timeout"))
	if err != nil {
		errorResponse(w, models.M_UNKNOWN, http.StatusBadRequest, "timeout parse failed")
		return
	}
	request.Timeout = timeout

	token := getTokenFromResponse(r)
	if token == "" {
		errorResponse(w, models.M_FORBIDDEN, http.StatusForbidden, "")
		return
	}

	user := currServer.Backend.GetUserByToken(token)
	if user == nil {
		errorResponse(w, models.M_UNKNOWN_TOKEN, http.StatusBadRequest, "")
		return
	}

	response, _ := user.Sync(token, request) // TODO: handle error

	sendJsonResponse(w, http.StatusOK, response)
}

// https://matrix.org/docs/spec/client_server/latest#get-matrix-client-r0-capabilities
func CapabilitiesHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		errorResponse(w, models.M_UNKNOWN, http.StatusBadRequest, "wrong method: "+r.Method)
		return
	}

	token := getTokenFromResponse(r)
	if token == "" {
		errorResponse(w, models.M_FORBIDDEN, http.StatusForbidden, "")
		return
	}

	user := currServer.Backend.GetUserByToken(token)
	if user == nil {
		errorResponse(w, models.M_UNKNOWN_TOKEN, http.StatusBadRequest, "")
		return
	}

	var response capabilities.Response
	response.Capabilities = currServer.Capabilities

	sendJsonResponse(w, http.StatusOK, response)
}

//
func AddFilterHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		errorResponse(w, models.M_UNKNOWN, http.StatusBadRequest, "wrong method: "+r.Method)
		return
	}

	token := getTokenFromResponse(r)
	if token == "" {
		errorResponse(w, models.M_FORBIDDEN, http.StatusForbidden, "")
		return
	}

	user := currServer.Backend.GetUserByToken(token)
	if user == nil {
		errorResponse(w, models.M_UNKNOWN_TOKEN, http.StatusBadRequest, "")
		return
	}

	var request filter.Request
	err := getRequest(r, &request)
	if err != nil {
		errorResponse(w, models.M_BAD_JSON, http.StatusBadRequest, err.Error())
		return
	}

	filterID := RandomString(12)
	user.AddFilter(filterID, common.Filter(request))

	response := filter.Response{FilterID: filterID}

	sendJsonResponse(w, http.StatusOK, response)
}

func GetFilterHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		errorResponse(w, models.M_UNKNOWN, http.StatusBadRequest, "wrong method: "+r.Method)
		return
	}

	token := getTokenFromResponse(r)
	if token == "" {
		errorResponse(w, models.M_FORBIDDEN, http.StatusForbidden, "")
		return
	}

	user := currServer.Backend.GetUserByToken(token)
	if user == nil {
		errorResponse(w, models.M_UNKNOWN_TOKEN, http.StatusBadRequest, "")
		return
	}

	filter := user.GetFilterByID(mux.Vars(r)["filterID"])
	if filter == nil {
		errorResponse(w, models.M_INVALID_PARAM, http.StatusNotFound, "")
		return
	}

	sendJsonResponse(w, http.StatusOK, filter)
}

// https://matrix.org/docs/spec/client_server/latest#get-matrix-client-r0-devices
func DevicesHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		errorResponse(w, models.M_UNKNOWN, http.StatusBadRequest, "wrong method: "+r.Method)
		return
	}

	token := getTokenFromResponse(r)
	if token == "" {
		errorResponse(w, models.M_FORBIDDEN, http.StatusForbidden, "")
		return
	}

	user := currServer.Backend.GetUserByToken(token)
	if user == nil {
		errorResponse(w, models.M_UNKNOWN_TOKEN, http.StatusBadRequest, "")
		return
	}

	var response devices.Response
	response.Devices = user.Devices()

	sendJsonResponse(w, http.StatusOK, response)
}

// https://matrix.org/docs/spec/client_server/latest#get-matrix-client-r0-register-available
func registerAvailableHandler(w http.ResponseWriter, r *http.Request) {
	var request registeravailable.Request

	err := getRequest(r, &request)
	if err != nil {
		errorResponse(w, models.M_BAD_JSON, http.StatusBadRequest, err.Error())
		return
	}

	user := currServer.Backend.GetUserByName(request.Username) // TODO: add validation of username
	if user != nil {
		errorResponse(w, models.M_USER_IN_USE, http.StatusBadRequest, "Desired user ID is already taken.")
		return
	}

	response := registeravailable.Response{Available: false}
	sendJsonResponse(w, http.StatusOK, response)
}

// https://matrix.org/docs/spec/client_server/latest#get-matrix-client-r0-directory-list-room-roomid
// https://matrix.org/docs/spec/client_server/latest#put-matrix-client-r0-directory-list-room-roomid
func listRoomHandler(w http.ResponseWriter, r *http.Request) {
	room := currServer.Backend.GetRoomByID(mux.Vars(r)["roomID"]) // TODO: can ["roomID"] throw panic?
	if room == nil {
		errorResponse(w, models.M_NOT_FOUND, http.StatusBadRequest, "room not found")
		return
	}

	switch r.Method {
	case http.MethodGet:
		response := listroom.Response{
			Visibility: room.Visibility()}

		sendJsonResponse(w, http.StatusOK, response)
	case http.MethodPut:
		token := getTokenFromResponse(r)
		if token == "" {
			errorResponse(w, models.M_FORBIDDEN, http.StatusForbidden, "")
			return
		}

		user := currServer.Backend.GetUserByToken(token)
		if user == nil {
			errorResponse(w, models.M_UNKNOWN_TOKEN, http.StatusBadRequest, "")
			return
		}

		var request listroom.Request
		err := getRequest(r, &request)
		if err != nil {
			errorResponse(w, models.M_BAD_JSON, http.StatusBadRequest, err.Error())
			return
		}
		user.SetRoomVisibility(room, request.Visibility)

		sendJsonResponse(w, http.StatusOK, struct{}{})
	default:
		errorResponse(w, models.M_UNKNOWN, http.StatusBadRequest, "wrong method: "+r.Method)
	}
}

// https://matrix.org/docs/spec/client_server/latest#id335
func publicRoomsHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet && r.Method != http.MethodPost {
		errorResponse(w, models.M_UNKNOWN, http.StatusBadRequest, "wrong method: "+r.Method)
		return
	}

	var request publicrooms.Request
	err := getRequest(r, &request)
	if err != nil {
		errorResponse(w, models.M_BAD_JSON, http.StatusBadRequest, err.Error())
		return
	}

	if request.Limit <= 0 {
		request.Limit = 50 // TODO: move to const
	}

	if r.Method == http.MethodPost {
		token := getTokenFromResponse(r)
		if token == "" {
			errorResponse(w, models.M_FORBIDDEN, http.StatusForbidden, "")
			return
		}

		user := currServer.Backend.GetUserByToken(token)
		if user == nil {
			errorResponse(w, models.M_UNKNOWN_TOKEN, http.StatusBadRequest, "")
			return
		}
	}

	publicRooms := currServer.Backend.PublicRooms(request.Filter.GenericSearchTerm) // TODO: make Post request as User method
	chunks := roomsToPublicRoomsChunks(publicRooms)

	var response publicrooms.Response

	// TODO: test and rewrite this code
	if request.Since == "" {
		if request.Limit >= len(chunks) {
			response.Chunk = chunks
			// TODO: should fill response.TotalRoomCountEstimate?
		} else {
			response.Chunk = chunks[:request.Limit]
			response.NextBatch = strconv.Itoa(request.Limit + 1)
			response.TotalRoomCountEstimate = len(chunks)
		}
	} else {
		response.PrevBatch = "0"

		from, err := strconv.Atoi(request.Since)
		if err != nil {
			errorResponse(w, models.M_INVALID_PARAM, http.StatusBadRequest, "Wrong Since field specified") // TODO: check code
			return
		}
		if len(chunks) >= from {
			if request.Limit >= len(chunks) {
				response.Chunk = chunks[from : from+request.Limit]
			} else {
				response.Chunk = chunks[from:]
			}
		}
	}
	sendJsonResponse(w, http.StatusOK, response)
}

// https://matrix.org/docs/spec/client_server/latest#put-matrix-client-r0-directory-room-roomalias
// https://matrix.org/docs/spec/client_server/latest#get-matrix-client-r0-directory-room-roomalias
// https://matrix.org/docs/spec/client_server/latest#delete-matrix-client-r0-directory-room-roomalias
func roomAliasHandler(w http.ResponseWriter, r *http.Request) {
	roomAlias := mux.Vars(r)["roomAlias"] // TODO: add validation of room alias

	var user User

	if r.Method == http.MethodPut || r.Method == http.MethodDelete {
		token := getTokenFromResponse(r)
		if token == "" {
			errorResponse(w, models.M_FORBIDDEN, http.StatusForbidden, "")
			return
		}

		user = currServer.Backend.GetUserByToken(token)
		if user == nil {
			errorResponse(w, models.M_UNKNOWN_TOKEN, http.StatusBadRequest, "")
			return
		}
	}

	var request roomalias.Request
	err := getRequest(r, &request)
	if err != nil {
		errorResponse(w, models.M_BAD_JSON, http.StatusBadRequest, err.Error())
		return
	}

	var response interface{}

	switch r.Method {
	case http.MethodGet:
		room := currServer.Backend.GetRoomByAlias(StripAlias(currServer.Address, roomAlias))
		if room == nil {
			errorResponse(w, models.M_NOT_FOUND, http.StatusNotFound, "room not found")
			return
		}

		response = roomalias.ResponseGet{
			RoomID:  room.ID(),
			Servers: []string{currServer.Address}}

	case http.MethodPut:
		room := currServer.Backend.GetRoomByID(request.RoomID)
		if room == nil {
			errorResponse(w, models.M_NOT_FOUND, http.StatusNotFound, "room not found")
			return
		}

		err := user.AddRoomAlias(room, roomAlias)
		if err != nil {
			errorResponse(w, err, http.StatusConflict, "") // TODO: check http code
			return
		}

		response = struct{}{}
	case http.MethodDelete:
		err := user.DeleteRoomAlias(StripAlias(currServer.Address, roomAlias))
		if err != nil {
			errorResponse(w, err, http.StatusConflict, "") // TODO: check http code
			return
		}

		response = struct{}{}
	}

	sendJsonResponse(w, http.StatusOK, response)
}

func sendJsonResponse(w http.ResponseWriter, httpStatus int, data interface{}) error {
	b, err := json.Marshal(data)
	if err != nil {
		return err
	}

	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(httpStatus)
	_, err = w.Write(b) // TODO: handle n
	return err
}

func getRequest(r *http.Request, request interface{}) error {
	b, err := ioutil.ReadAll(r.Body)
	if err != nil {
		return err
	}

	return json.Unmarshal(b, request)
}