package telegram

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

const badChars = "_*[]()~`>#+-=|{}.!"

type Client struct {
	Token       string
	Offset      int64
	PollTimeout int64
}

func (c *Client) Get(url string) ([]byte, error) {
	resp, err := http.Get("https://api.telegram.org/bot" + c.Token + url)
	if err != nil {
		return nil, err
	}

	return ioutil.ReadAll(resp.Body)
}

func (c *Client) Post(url string, data url.Values) ([]byte, error) {
	res, err := http.PostForm("https://api.telegram.org/bot"+c.Token+url, data)
	if err != nil {
		return nil, err
	}

	return ioutil.ReadAll(res.Body)
}

func (c *Client) GetUpdates() (Response, error) {
	var res Response

	values := url.Values{}
	values.Set("offset", strconv.FormatInt(c.Offset, 10))
	values.Set("timeout", strconv.FormatInt(c.PollTimeout, 10))
	body, err := c.Get("/getUpdates?" + values.Encode())
	if err != nil {
		return res, err
	}

	res.Raw = string(body)
	err = json.Unmarshal(body, &res)

	if len(res.Result) > 0 {
		c.Offset = res.Result[len(res.Result)-1].UpdateID + 1
	}

	return res, err
}

func EscapeMarkdown(msg string) string {
	for _, char := range badChars {
		ch := string(char)
		msg = strings.Replace(msg, ch, "\\"+ch, -1)
	}
	return msg
}

func (c *Client) SendMarkdownMessage(chatId, body string) (*SendMessageResponse, error) {
	return c.SendMessage(chatId, body, url.Values{"parse_mode": {"MarkdownV2"}})
}

func mergeValues(a url.Values, b []url.Values) {
	for _, vals := range b {
		for key, val := range vals {
			a[key] = val
		}
	}
}

func (c *Client) SendMessage(chatId, text string, options ...url.Values) (ret *SendMessageResponse, err error) {
	values := url.Values{
		"chat_id": {chatId},
		"text":    {text},
	}
	mergeValues(values, options)

	body, err := c.Post("/sendMessage", values)
	if err != nil {
		return nil, err
	}

	var res SendMessageResponse
	err = json.Unmarshal(body, &res)
	return &res, err
}

func (c *Client) EditMessageText(chatId, messageId, text string, options ...url.Values) (ret *SendMessageResponse, err error) {
	values := url.Values{
		"chat_id":    {chatId},
		"message_id": {messageId},
		"text":       {text},
	}
	mergeValues(values, options)

	body, err := c.Post("/editMessageText", values)
	if err != nil {
		return nil, err
	}

	var res SendMessageResponse
	err = json.Unmarshal(body, &res)
	return &res, err
}