package telegram

import (
	"fmt"
	"github.com/pkg/errors"
	"math"
	"regexp"
	"strconv"
	"strings"
	"time"

	"dev.narayana.im/narayana/telegabber/xmpp/gateway"

	log "github.com/sirupsen/logrus"
	"github.com/zelenin/go-tdlib/client"
)

const notEnoughArguments string = "Not enough arguments"
const telegramNotInitialized string = "Telegram connection is not initialized yet"
const notOnline string = "Not online"

var transportCommands = map[string]command{
	"login":       command{"phone", "sign in"},
	"logout":      command{"", "sign out"},
	"code":        command{"", "check one-time code"},
	"password":    command{"", "check 2fa password"},
	"setusername": command{"", "update @username"},
	"setname":     command{"first last", "update name"},
	"setbio":      command{"", "update about"},
	"setpassword": command{"[old] [new]", "set or remove password"},
	"config":      command{"[param] [value]", "view or update configuration options"},
}

var chatCommands = map[string]command{
	"d":          command{"[n]", "delete your last message(s)"},
	"s":          command{"regex replace", "edit your last message"},
	"add":        command{"@username", "add @username to your chat list"},
	"join":       command{"https://t.me/invite_link", "join to chat via invite link"},
	"group":      command{"title", "create groupchat «title» with current user"},
	"supergroup": command{"title description", "create new supergroup «title» with «description»"},
	"channel":    command{"title description", "create new channel «title» with «description»"},
	"secret":     command{"", "create secretchat with current user"},
	"search":     command{"string [limit]", "search <string> in current chat"},
	"history":    command{"[limit]", "get last [limit] messages from current chat"},
	"block":      command{"", "blacklist current user"},
	"unblock":    command{"", "unblacklist current user"},
	"invite":     command{"id or @username", "add user to current chat"},
	"kick":       command{"id or @username", "remove user to current chat"},
	"ban":        command{"id or @username [hours]", "restrict @username from current chat for [hours] or forever"},
	"leave":      command{"", "leave current chat"},
	"close":      command{"", "close current secret chat"},
	"delete":     command{"", "delete current chat from chat list"},
	"members":    command{"[query]", "search members [by optional query] in current chat (requires admin rights)"},
}

var transportConfigurationOptions = map[string]configurationOption{
	"timezone": configurationOption{"00:00", "adjust timezone for Telegram user statuses"},
}

type command struct {
	arguments   string
	description string
}
type configurationOption command

type helpType int

const (
	helpTypeTransport helpType = iota
	helpTypeChat
)

func helpString(ht helpType) string {
	var str strings.Builder
	var commandMap map[string]command

	switch ht {
	case helpTypeTransport:
		commandMap = transportCommands
	case helpTypeChat:
		commandMap = chatCommands
	}

	str.WriteString("Available commands:\n")
	for name, command := range commandMap {
		str.WriteString("/")
		str.WriteString(name)
		if command.arguments != "" {
			str.WriteString(" ")
			str.WriteString(command.arguments)
		}
		str.WriteString(" — ")
		str.WriteString(command.description)
		str.WriteString("\n")
	}

	if ht == helpTypeTransport {
		str.WriteString("Configuration options\n")
		for name, option := range transportConfigurationOptions {
			str.WriteString(name)
			str.WriteString(" ")
			str.WriteString(option.arguments)
			str.WriteString(" — ")
			str.WriteString(option.description)
			str.WriteString("\n")
		}
	}

	return str.String()
}

func parseCommand(cmdline string) (string, []string) {
	bodyFields := strings.Fields(cmdline)
	return bodyFields[0][1:], bodyFields[1:]
}

func (c *Client) unsubscribe(chatID int64) {
	gateway.SendPresence(
		c.xmpp,
		c.jid,
		gateway.SPFrom(strconv.FormatInt(chatID, 10)),
		gateway.SPType("unsubscribed"),
	)
}

func (c *Client) sendMessagesReverse(chatID int64, messages []*client.Message) {
	for i := len(messages) - 1; i >= 0; i-- {
		gateway.SendMessage(
			c.jid,
			strconv.FormatInt(chatID, 10),
			c.formatMessage(0, 0, false, messages[i]),
			c.xmpp,
		)
	}
}

func (c *Client) usernameOrIDToID(username string) (int32, error) {
	userID, err := strconv.ParseInt(username, 10, 32)
	// couldn't parse the id, try to lookup as a username
	if err != nil {
		chat, err := c.client.SearchPublicChat(&client.SearchPublicChatRequest{
			Username: username,
		})
		if err != nil {
			return 0, err
		}

		userID = chat.Id
		if userID <= 0 || userID > math.MaxInt32 {
			return 0, errors.New("Not a user")
		}
	}

	return int32(userID), nil
}

// ProcessTransportCommand executes a command sent directly to the component
// and returns a response
func (c *Client) ProcessTransportCommand(cmdline string) string {
	cmd, args := parseCommand(cmdline)
	switch cmd {
	case "login", "code", "password":
		if cmd == "login" && c.Session.Login != "" {
			return ""
		}

		if len(args) < 1 {
			return notEnoughArguments
		}

		if cmd == "login" {
			wasSessionLoginEmpty := c.Session.Login == ""
			c.Session.Login = args[0]

			if wasSessionLoginEmpty && c.authorizer == nil {
				go func() {
					err := c.Connect()
					if err != nil {
						log.Error(errors.Wrap(err, "TDlib connection failure"))
					}
				}()
				// a quirk for authorizer to become ready. If it's still not,
				// nothing bad: the command just needs to be resent again
				time.Sleep(1e5)
			}
		}

		if c.authorizer == nil {
			return telegramNotInitialized
		}

		switch cmd {
		// sign in
		case "login":
			c.authorizer.PhoneNumber <- args[0]
		// check auth code
		case "code":
			c.authorizer.Code <- args[0]
		// check auth password
		case "password":
			c.authorizer.Password <- args[0]
		}
	// sign out
	case "logout":
		if !c.Online() {
			return notOnline
		}

		for _, id := range c.cache.ChatsKeys() {
			c.unsubscribe(id)
		}

		_, err := c.client.LogOut()
		if err != nil {
			c.forceClose()
			return errors.Wrap(err, "Logout error").Error()
		}

		c.Session.Login = ""
	// set @username
	case "setusername":
		if !c.Online() {
			return notOnline
		}

		var username string
		if len(args) > 0 {
			username = args[0]
		}

		_, err := c.client.SetUsername(&client.SetUsernameRequest{
			Username: username,
		})
		if err != nil {
			return errors.Wrap(err, "Couldn't set username").Error()
		}
	// set My Name
	case "setname":
		if !c.Online() {
			return notOnline
		}

		var firstname string
		var lastname string
		if len(args) > 0 {
			firstname = args[0]
		}
		if len(args) > 1 {
			lastname = args[1]
		}

		_, err := c.client.SetName(&client.SetNameRequest{
			FirstName: firstname,
			LastName:  lastname,
		})
		if err != nil {
			return errors.Wrap(err, "Couldn't set name").Error()
		}
	// set About
	case "setbio":
		if !c.Online() {
			return notOnline
		}

		_, err := c.client.SetBio(&client.SetBioRequest{
			Bio: strings.Join(args, " "),
		})
		if err != nil {
			return errors.Wrap(err, "Couldn't set bio").Error()
		}
	// set password
	case "setpassword":
		if !c.Online() {
			return notOnline
		}

		var oldPassword string
		var newPassword string
		// 0 or 1 argument is ignored and the password is reset
		if len(args) > 1 {
			oldPassword = args[0]
			newPassword = args[1]
		}
		_, err := c.client.SetPassword(&client.SetPasswordRequest{
			OldPassword: oldPassword,
			NewPassword: newPassword,
		})
		if err != nil {
			return errors.Wrap(err, "Couldn't set password").Error()
		}
	case "config":
		if len(args) > 1 {
			value, err := c.Session.Set(args[0], args[1])
			if err != nil {
				return err.Error()
			}

			return fmt.Sprintf("%s set to %s", args[0], value)
		} else if len(args) > 0 {
			value, err := c.Session.Get(args[0])
			if err != nil {
				return err.Error()
			}

			return fmt.Sprintf("%s is set to %s", args[0], value)
		}

		var entries []string
		for key, value := range c.Session.ToMap() {
			entries = append(entries, fmt.Sprintf("%s is set to %s", key, value))
		}

		return strings.Join(entries, "\n")
	case "help":
		return helpString(helpTypeTransport)
	}

	return ""
}

// ProcessChatCommand executes a command sent in a mapped chat
// and returns a response and the status of command support
func (c *Client) ProcessChatCommand(chatID int64, cmdline string) (string, bool) {
	if !c.Online() {
		return notOnline, true
	}

	cmd, args := parseCommand(cmdline)
	switch cmd {
	// delete last message(s)
	case "d":
		if c.me == nil {
			return "@me is not initialized", true
		}

		var limit int32
		if len(args) > 0 {
			limit64, err := strconv.ParseInt(args[0], 10, 32)
			if err != nil {
				return err.Error(), true
			}
			limit = int32(limit64)
		} else {
			limit = 1
		}

		messages, err := c.client.SearchChatMessages(&client.SearchChatMessagesRequest{
			ChatId:       chatID,
			Limit:        limit,
			SenderUserId: c.me.Id,
			Filter:       &client.SearchMessagesFilterEmpty{},
		})
		if err != nil {
			return err.Error(), true
		}
		log.Debugf("pre-deletion query: %#v %#v", messages, messages.Messages)

		var messageIds []int64
		for _, message := range messages.Messages {
			if message != nil {
				messageIds = append(messageIds, message.Id)
			}
		}

		_, err = c.client.DeleteMessages(&client.DeleteMessagesRequest{
			ChatId:     chatID,
			MessageIds: messageIds,
			Revoke:     true,
		})
		if err != nil {
			return err.Error(), true
		}
	// edit last message
	case "s":
		if c.me == nil {
			return "@me is not initialized", true
		}
		if len(args) < 2 {
			return "Not enough arguments", true
		}
		regex, err := regexp.Compile(args[0])
		if err != nil {
			return err.Error(), true
		}

		messages, err := c.client.SearchChatMessages(&client.SearchChatMessagesRequest{
			ChatId:       chatID,
			Limit:        1,
			SenderUserId: c.me.Id,
			Filter:       &client.SearchMessagesFilterEmpty{},
		})
		if err != nil {
			return err.Error(), true
		}
		if len(messages.Messages) == 0 {
			return "No last message", true
		}

		message := messages.Messages[0]
		if message == nil {
			return "Last message is empty", true
		}

		messageText, ok := message.Content.(*client.MessageText)
		if !ok {
			return "Last message is not a text!", true
		}

		text := regex.ReplaceAllString(messageText.Text.Text, strings.Join(args[1:], " "))
		c.ProcessOutgoingMessage(chatID, text, message.Id, "")
	// add @contact
	case "add":
		if len(args) < 1 {
			return notEnoughArguments, true
		}

		chat, err := c.client.SearchPublicChat(&client.SearchPublicChatRequest{
			Username: args[0],
		})
		if err != nil {
			return err.Error(), true
		}
		if chat == nil {
			return "No error, but chat is nil", true
		}

		gateway.SendPresence(
			c.xmpp,
			c.jid,
			gateway.SPFrom(strconv.FormatInt(chat.Id, 10)),
			gateway.SPType("subscribe"),
		)
	// join https://t.me/publichat
	case "join":
		if len(args) < 1 {
			return notEnoughArguments, true
		}

		_, err := c.client.JoinChatByInviteLink(&client.JoinChatByInviteLinkRequest{
			InviteLink: args[0],
		})
		if err != nil {
			return err.Error(), true
		}
	// create new supergroup
	case "supergroup":
		if len(args) < 1 {
			return notEnoughArguments, true
		}

		_, err := c.client.CreateNewSupergroupChat(&client.CreateNewSupergroupChatRequest{
			Title:       args[0],
			Description: strings.Join(args[1:], " "),
		})
		if err != nil {
			return err.Error(), true
		}
	// create new channel
	case "channel":
		if len(args) < 1 {
			return notEnoughArguments, true
		}

		_, err := c.client.CreateNewSupergroupChat(&client.CreateNewSupergroupChatRequest{
			Title:       args[0],
			Description: strings.Join(args[1:], " "),
			IsChannel:   true,
		})
		if err != nil {
			return err.Error(), true
		}
	// create new secret chat with current user
	case "secret":
		_, user, err := c.GetContactByID(chatID, nil)
		if err != nil || user == nil {
			return "User not found", true
		}

		_, err = c.client.CreateNewSecretChat(&client.CreateNewSecretChatRequest{
			UserId: int32(chatID),
		})
		if err != nil {
			return err.Error(), true
		}
	// create group chat with current user
	case "group":
		if len(args) < 1 {
			return notEnoughArguments, true
		}

		if chatID > 0 {
			_, err := c.client.CreateNewBasicGroupChat(&client.CreateNewBasicGroupChatRequest{
				UserIds: []int32{int32(chatID)},
				Title:   args[0],
			})
			if err != nil {
				return err.Error(), true
			}
		}
	// blacklists current user
	case "block":
		if chatID > 0 {
			_, err := c.client.BlockUser(&client.BlockUserRequest{
				UserId: int32(chatID),
			})
			if err != nil {
				return err.Error(), true
			}
		}
	// unblacklists current user
	case "unblock":
		if chatID > 0 {
			_, err := c.client.UnblockUser(&client.UnblockUserRequest{
				UserId: int32(chatID),
			})
			if err != nil {
				return err.Error(), true
			}
		}
	// invite @username to current groupchat
	case "invite":
		if len(args) < 1 {
			return notEnoughArguments, true
		}

		if chatID < 0 {
			userID, err := c.usernameOrIDToID(args[0])
			if err != nil {
				return err.Error(), true
			}

			_, err = c.client.AddChatMember(&client.AddChatMemberRequest{
				ChatId: chatID,
				UserId: userID,
			})
			if err != nil {
				return err.Error(), true
			}
		}
	// kick @username from current group chat
	case "kick":
		if len(args) < 1 {
			return notEnoughArguments, true
		}

		if chatID < 0 {
			userID, err := c.usernameOrIDToID(args[0])
			if err != nil {
				return err.Error(), true
			}

			_, err = c.client.SetChatMemberStatus(&client.SetChatMemberStatusRequest{
				ChatId: chatID,
				UserId: userID,
				Status: &client.ChatMemberStatusLeft{},
			})
			if err != nil {
				return err.Error(), true
			}
		}
	// ban @username from current chat [for N hours]
	case "ban":
		if len(args) < 1 {
			return notEnoughArguments, true
		}

		if chatID < 0 {
			userID, err := c.usernameOrIDToID(args[0])
			if err != nil {
				return err.Error(), true
			}

			var until int32
			if len(args) > 1 {
				hours, err := strconv.ParseInt(args[1], 10, 32)
				if err != nil {
					until = int32(time.Now().Unix() + hours*3600)
				}
			}

			_, err = c.client.SetChatMemberStatus(&client.SetChatMemberStatusRequest{
				ChatId: chatID,
				UserId: userID,
				Status: &client.ChatMemberStatusBanned{
					BannedUntilDate: until,
				},
			})
			if err != nil {
				return err.Error(), true
			}
		}
	// leave current chat
	case "leave":
		chat, _, err := c.GetContactByID(chatID, nil)
		if err != nil {
			return err.Error(), true
		}

		chatType := chat.Type.ChatTypeType()
		if chatType == client.TypeChatTypeBasicGroup || chatType == client.TypeChatTypeSupergroup {
			_, err = c.client.LeaveChat(&client.LeaveChatRequest{
				ChatId: chatID,
			})
			if err != nil {
				return err.Error(), true
			}

			c.unsubscribe(chatID)
		}
	// close secret chat
	case "close":
		chat, _, err := c.GetContactByID(chatID, nil)
		if err != nil {
			return err.Error(), true
		}

		chatType := chat.Type.ChatTypeType()
		if chatType == client.TypeChatTypeSecret {
			chatTypeSecret, _ := chat.Type.(*client.ChatTypeSecret)
			_, err = c.client.CloseSecretChat(&client.CloseSecretChatRequest{
				SecretChatId: chatTypeSecret.SecretChatId,
			})
			if err != nil {
				return err.Error(), true
			}

			c.unsubscribe(chatID)
		}
	// delete current chat
	case "delete":
		_, err := c.client.DeleteChatHistory(&client.DeleteChatHistoryRequest{
			ChatId:             chatID,
			RemoveFromChatList: true,
		})
		if err != nil {
			return err.Error(), true
		}

		c.unsubscribe(chatID)
	// search messages within current chat
	case "search":
		var limit int32 = 10
		if len(args) > 1 {
			newLimit, err := strconv.ParseInt(args[1], 10, 32)
			if err == nil {
				limit = int32(newLimit)
			}
		}

		var query string
		if len(args) > 0 {
			query = args[0]
		}

		messages, err := c.client.SearchChatMessages(&client.SearchChatMessagesRequest{
			ChatId: chatID,
			Query:  query,
			Limit:  limit,
			Filter: &client.SearchMessagesFilterEmpty{},
		})
		if err != nil {
			return err.Error(), true
		}

		c.sendMessagesReverse(chatID, messages.Messages)
	// get latest entries from history
	case "history":
		var limit int32 = 10
		if len(args) > 0 {
			newLimit, err := strconv.ParseInt(args[0], 10, 32)
			if err == nil {
				limit = int32(newLimit)
			}
		}

		messages, err := c.client.GetChatHistory(&client.GetChatHistoryRequest{
			ChatId: chatID,
			Limit:  limit,
		})
		if err != nil {
			return err.Error(), true
		}

		c.sendMessagesReverse(chatID, messages.Messages)
	// members list (for admins)
	case "members":
		var query string
		if len(args) > 0 {
			query = args[0]
		}

		members, err := c.client.SearchChatMembers(&client.SearchChatMembersRequest{
			ChatId: chatID,
			Limit:  9999,
			Query:  query,
			Filter: &client.ChatMembersFilterMembers{},
		})
		if err != nil {
			return err.Error(), true
		}

		var entries []string
		for _, member := range members.Members {
			entries = append(entries, fmt.Sprintf(
				"%v | role: %v",
				c.formatContact(int64(member.UserId)),
				member.Status.ChatMemberStatusType(),
			))
		}

		gateway.SendMessage(
			c.jid,
			strconv.FormatInt(chatID, 10),
			strings.Join(entries, "\n"),
			c.xmpp,
		)
	case "help":
		return helpString(helpTypeChat), true
	default:
		return "", false
	}

	return "", true
}