package cmd

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

	"github.com/kf5grd/keybasebot"
	"github.com/teris-io/shortid"
	"samhofi.us/x/keybase/v2/types/chat1"
)

var ConvertAd = chat1.UserBotCommandInput{
	Name:        "convert",
	Usage:       "<currency> to <currency>",
	Description: "Converts between many crypto and fiat currencies.  Try !convert 50 USD to XLM",
}

func Convert(m chat1.MsgSummary, b *keybasebot.Bot) (bool, error) {
	fields := strings.Fields(strings.TrimSpace(strings.Replace(m.Content.Text.Body, "!convert", "", 1)))

	// first pass filters
	if fields == nil || len(fields) != 4 || fields[2] != "to" {
		return true, fmt.Errorf("@%s - Invalid Request.", m.Sender.Username)
	}

	// get the arguments
	lhq := fields[0]
	lhc := strings.ToUpper(fields[1])
	rhc := strings.ToUpper(fields[3])

	// validate the args
	leftQuantity, err := strconv.ParseFloat(lhq, 64)
	if err != nil {
		return true, fmt.Errorf("@%s - Unable to parse %s into a number", m.Sender.Username, lhq)
	}
	if !isAlpha(lhc) || !isAlpha(rhc) {
		return true, fmt.Errorf("@%s - Only letters are allowed in currency symbols", m.Sender.Username)
	}
	rate, err := getConversion(lhc, rhc)
	if err != nil {
		eid := shortid.MustGenerate()
		b.Logger.Error("%s: %+v", eid, err)
		b.KB.ReactByConvID(m.ConvID, m.Id, "Error: %s", eid)
		return true, nil
	}
	rhq := leftQuantity * rate
	b.KB.ReactByConvID(m.ConvID, m.Id, fmt.Sprintf("%.4f %s", rhq, rhc))
	return true, nil
}

func getConversion(lhc string, rhc string) (float64, error) {
	client := &http.Client{}
	target := fmt.Sprintf("https://api.cryptonator.com/api/ticker/%s-%s", lhc, rhc)
	req, err := http.NewRequest("GET", target, nil)
	if err != nil {
		return 0.0, err
	}
	req.Header.Set("User-Agent", "GoLang Currency Bot ssh0le/0.99")
	resp, err := client.Do(req)
	if err != nil {
		return 0.0, err
	}
	defer resp.Body.Close()
	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return 0.0, err
	}
	var apiResponse CryptApiResponse
	if err := json.Unmarshal(body, &apiResponse); err != nil {
		return 0.0, err
	}
	if !apiResponse.Success {
		return 0.0, fmt.Errorf(apiResponse.Error)
	}
	result, err := strconv.ParseFloat(apiResponse.Ticker.Price, 64)
	if err != nil {
		return 0.0, err
	}
	return result, nil
}

func isAlpha(s string) bool {
	for _, letter := range s {
		if !unicode.IsLetter(letter) {
			return false
		}
	}
	return true
}