package main

import (
	"errors"
	"io/ioutil"
	"net/http"
	"strconv"
	"strings"
	"time"
)

type line struct {
	Date              time.Time
	Operation         string
	Cryptocurrency    string
	Amount            float64
	TransactionID     string
	WithdrawalAddress string
	Reference         string
}

// Upload needs a comment
func Upload(w http.ResponseWriter, r *http.Request) {
	type data struct {
		Title             string
		Uploaded          bool
		Success           bool
		Rewards           map[time.Month]string
		CumulativeRewards map[time.Month]string
		Color             string
		Currency          string
	}

	// set common attributes
	d := data{
		Title: "Monthly Rewards",
	}

	// check the method used to access this site (GET/POST)
	switch r.Method {

	case http.MethodGet:
		// display upload site
		d.Uploaded = false
		d.Success = false
		render(w, "rewards.html", d)

	case http.MethodPost:
		// upload the file that was posted here
		var success bool = false
		lines, err := uploadFile(w, r)
		if err == nil {
			success = true
		}

		// prepare data for usage
		var color string
		var currency string
		var rewards map[time.Month]string
		if success == true {
			currency = lines[1].Cryptocurrency
			color, _ = getCurrencyOpts(currency)
			rewards = monthlyRewardOverview(lines)
		}

		// prettify.Print(rewards)
		d.Uploaded = true
		d.Success = success
		d.Rewards = rewards
		d.Color = color
		d.Currency = currency
		render(w, "rewards.html", d)
	}
	// create a new line instance
}

func uploadFile(w http.ResponseWriter, r *http.Request) ([]line, error) {
	// Maximum upload of 10 MB files
	r.ParseMultipartForm(10 << 20)

	// Get handler for filename, size and headers
	file, handler, err := r.FormFile("csvFile")
	if err != nil {
		return nil, err
	}

	defer file.Close()

	// check if we got a csv file
	if handler.Header["Content-Type"][0] == "text/csv" {
		// accept this gift and read content of file
		fileContents, err := ioutil.ReadAll(file)
		if err != nil {
			return nil, err
		}

		// read uploaded file
		lines := readUploadedFile(fileContents)
		return lines, err
	}
	return nil, errors.New("please only upload .csv files")
}

func getCurrencyOpts(currency string) (color string, precision int) {
	// set default precision
	precision = 8

	// set other options according to the coin
	switch currency {
	case "BTC": // Bitcoin
		color = "#F7931A"
	case "DASH":
		color = "#008de4"
	case "DFI": // DeFiChain
		color = "#fd0bb0"
	case "ETH": // Ethereum
		color = "#627eea"
		precision = 18
	case "PIVX":
		color = "#5e4778"
		precision = 9
	case "XZC": // Zcoin
		color = "#24b852"
	case "USDT": // Tether
		color = "#26a17b"
		precision = 6
	}
	return color, precision
}

func monthlyRewardOverview(lines []line) map[time.Month]string {
	// create a map to hold all months' sums
	sums := make(map[time.Month]float64)

	// loop through all lines
	for i := range lines {
		// filter out operations
		switch lines[i].Operation {
		case "Staking reward ", "Confectionery Lapis DFI Bonus ", "Lapis DFI Bonus ", "Lapis reward ", "Referral reward ":
			sums[lines[i].Date.Month()] += lines[i].Amount
		}
	}

	// get precision for specific coin
	_, precision := getCurrencyOpts(lines[0].Cryptocurrency)
	// fill empty data with zeroes
	sumsString := fillSums(sums, precision)

	return sumsString
}

func fillSums(s map[time.Month]float64, precision int) map[time.Month]string {
	// maps are always referenced by pointers
	// create empty map
	sumsString := make(map[time.Month]string)

	// loop through month
	for i := 1; i < 13; i++ {
		// check what month are missing in array
		if _, ok := s[time.Month(i)]; !ok {
			s[time.Month(i)] = 0
		}
		// format to strings
		sumsString[time.Month(i)] = strconv.FormatFloat(s[time.Month(i)], 'g', precision, 64)
	}
	return sumsString
}

func readUploadedFile(fileContents []byte) []line {
	var lines []line
	csvLines := strings.Split(string(fileContents), "\n")

	// loop through all lines (except headers)
	for _, csvLine := range csvLines[1:] {
		// split arguments by comma
		csvArgs := strings.Split(csvLine, ",")

		// fix stupid " in lines
		for i := range csvArgs {
			csvArgs[i] = strings.ReplaceAll(csvArgs[i], `"`, "")
		}

		// create output variable
		var l line

		// assign values from CSV file to output variable
		var err error
		l.Date, err = time.Parse(time.RFC3339, csvArgs[0])
		if err != nil {
			panic(err)
		}
		l.Operation = csvArgs[1]
		l.Cryptocurrency = csvArgs[2]
		l.Amount, _ = strconv.ParseFloat(csvArgs[3], 64)
		l.TransactionID = csvArgs[4]
		l.WithdrawalAddress = csvArgs[5]
		l.Reference = csvArgs[6]
		lines = append(lines, l)
	}
	return lines
}

func uploadHandler(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case "GET":
		render(w, "upload", nil)
	case "POST":
		uploadFile(w, r)
	}
}