package utils

import (
	"fmt"
	"strconv"
	"strings"
	"unicode/utf16"

	api "github.com/OvyFlash/telegram-bot-api"
)

func EscapeMarkdown(s string) string {
	replacer := strings.NewReplacer(
		"\\", "\\\\",
		"*", "\\*",
		"_", "\\_",
		"`", "\\`",
		"[", "\\[",
		"]", "\\]",
		"(", "\\(",
		")", "\\)",
		"#", "\\#",
		"-", "\\-",
	)
	return replacer.Replace(s)
}

func EscapeHTML(s string) string {
	replacer := strings.NewReplacer(
		"&", "&",
		"<", "&lt;",
		">", "&gt;",
		"\"", "&quot;",
	)
	return replacer.Replace(s)
}

func NewApprovalKeyboard(userID int64) api.InlineKeyboardMarkup {
	approveBtn := api.NewInlineKeyboardButtonData("Approve", fmt.Sprintf("approve_%d", userID))
	declineBtn := api.NewInlineKeyboardButtonData("Decline", fmt.Sprintf("decline_%d", userID))
	return api.NewInlineKeyboardMarkup([]api.InlineKeyboardButton{approveBtn, declineBtn})
}

func GetInfoFromMsg(msg string) (userId int64, username, joinReason, declinedBy, declinedAt string) {
	lines := strings.Split(msg, "\n")

	joinReason = string([]rune(lines[2])[len([]rune("Join reason: ")):])
	declinedBy = string([]rune(lines[3])[len([]rune("Declined by: ")):])
	declinedAt = string([]rune(lines[4])[len([]rune("Declined at: ")):])
	index := LastIndexRuneInRunes([]rune(lines[0]), '[')
	userID, _ := strconv.Atoi(string([]rune(lines[0])[index+1 : len([]rune(lines[0]))-1]))

	return int64(userID), EscapeHTML(username), EscapeHTML(joinReason), declinedBy, declinedAt
}

func LastIndexRuneInRunes(runes []rune, r rune) int {
	for i := len(runes) - 1; i >= 0; i-- {
		if runes[i] == r {
			return i
		}
	}
	return -1
}

type EntityWithText struct {
	Type   string `json:"type"`
	Offset int    `json:"offset"`
	Length int    `json:"length"`
	Text   string `json:"text"`
}

func FilterEntitiesByTypeWithContext(payload *api.Message, entityType string) ([]EntityWithText, error) {
	textRunes := utf16.Encode([]rune(payload.Text))
	var filtered []EntityWithText
	for _, entity := range payload.Entities {
		if entity.Type == entityType {
			endOffset := entity.Offset + entity.Length

			entityText := ""
			if entity.Offset < len(textRunes) {
				entityText = string(utf16.Decode(textRunes[entity.Offset:endOffset]))
			}

			filtered = append(filtered, EntityWithText{
				Type:   entity.Type,
				Offset: entity.Offset,
				Length: entity.Length,
				Text:   entityText,
			})
		}
	}

	return filtered, nil
}

func BuildUserString(user *api.User) string {
	if user.UserName != "" {
		return "@" + user.UserName
	}

	var name strings.Builder
	name.WriteString("<i>")
	if user.FirstName != "" {
		fmt.Fprint(&name, EscapeHTML(user.FirstName))
	}
	if user.LastName != "" {
		fmt.Fprintf(&name, " %s", EscapeHTML(user.LastName))
	}
	name.WriteString("</i>")
	return name.String()
}

func SendMessage(botAPI *api.BotAPI, chatID int64, topicID int, text string) (api.Message, error) {
	msg := api.NewMessage(chatID, text)
	msg.ParseMode = api.ModeHTML
	if topicID != 0 {
		msg.MessageThreadID = topicID
	}
	return botAPI.Send(msg)
}

func EditMessage(botAPI *api.BotAPI, chatID int64, messageID int, text string) (api.Message, error) {
	edit := api.NewEditMessageText(chatID, messageID, text)
	edit.ParseMode = api.ModeHTML
	return botAPI.Send(edit)
}

func LeaveChatRequest(botAPI *api.BotAPI, chatIDs []int64) error {
	for _, chatID := range chatIDs {
		_, err := botAPI.Request(api.LeaveChatConfig{ChatConfig: api.ChatConfig{ChatID: chatID}})
		if err != nil {
			return err
		}
	}
	return nil
}

func EditMessageWithKeyboard(botAPI *api.BotAPI, chatID int64, messageID int, text string, keyboard *api.InlineKeyboardMarkup) {
	edit := api.NewEditMessageText(chatID, messageID, text)
	edit.ParseMode = api.ModeHTML
	if keyboard != nil {
		edit.ReplyMarkup = keyboard
	}
	botAPI.Send(edit)
}

// ParseIntArg parses a string argument as int. Returns (value, errMsg); errMsg is empty on success.
func ParseIntArg(arg string) (int, string) {
	val, err := strconv.Atoi(arg)
	if err != nil {
		return 0, "Invalid value"
	}
	return val, ""
}

// ParseInt64Arg parses a string argument as int64. Returns (value, errMsg); errMsg is empty on success.
func ParseInt64Arg(arg string) (int64, string) {
	val, err := strconv.ParseInt(arg, 10, 64)
	if err != nil {
		return 0, "Invalid value"
	}
	return val, ""
}