package main

import (
	"errors"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"runtime"
	"strconv"
	"strings"
	"time"

	"github.com/lucasb-eyer/go-colorful"
)

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

type rewards struct {
	Staking       map[time.Month]string
	Confectionery map[time.Month]string
	LapisDFI      map[time.Month]string
	Lapis         map[time.Month]string
	Referral      map[time.Month]string
	Airdrop       map[time.Month]string
	Swapped       map[time.Month]string
}

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

	// 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
		var e string

		lines, err := uploadFile(w, r)
		if err == nil {
			success = true
		} else {
			e = err.Error()
		}

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

		// prettify.Print(rewards)
		d.Uploaded = true
		d.Success = success
		d.Rewards.Staking = rewards.Staking
		d.Rewards.Confectionery = rewards.Confectionery
		d.Rewards.Lapis = rewards.Lapis
		d.Rewards.LapisDFI = rewards.LapisDFI
		d.Rewards.Referral = rewards.Referral
		d.Color = color
		d.ColorAlt = getOtherColors(color, 2)
		d.ColorAltAlt = getOtherColors(color, 4)
		d.Currency = currency
		d.ErrorText = e
		render(w, "rewards.html", d)
	}
	// create a new line instance
}

func getOtherColors(color string, factor float64) string {
	col, err := colorful.Hex(color)
	if err != nil {
		log.Fatal(err)
	}
	// get r,g,b from color
	r, g, b := col.LinearRgb()
	// return color reduced in "brightness" by factor of f
	return colorful.LinearRgb(r/factor, g/factor, b/factor).Hex()
}

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

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

	defer file.Close()

	// check if we got a csv file
	switch handler.Header["Content-Type"][0] {
	case "text/csv", "application/vnd.ms-excel":
		// accept this gift and read content of file
		fileContents, err := ioutil.ReadAll(file)
		if err != nil {
			fmt.Println("file was uploaded but can't be read! 1", err)
			return nil, err
		}

		// read uploaded file
		lines, err := readUploadedFile(fileContents)
		if err != nil {
			return nil, fmt.Errorf("the .csv file could not be read, error was: %s", err)
		}
		return lines, err
	}
	return nil, errors.New("please only upload .csv files")
}

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

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

func monthlyRewardOverview(lines []line) rewards {
	// create a map to hold all months' sums
	staking := make(map[time.Month]float64)
	confectionery := make(map[time.Month]float64)
	lapisDFI := make(map[time.Month]float64)
	lapis := make(map[time.Month]float64)
	referral := make(map[time.Month]float64)
	airdrop := make(map[time.Month]float64)
	swapped := make(map[time.Month]float64)

	// loop through all lines
	for i := range lines {
		// filter out operations
		switch lines[i].Operation {
		case "Staking reward":
			staking[lines[i].Date.Month()] += lines[i].Amount
		case "Confectionery Lapis DFI Bonus":
			confectionery[lines[i].Date.Month()] += lines[i].Amount
		case "Lapis DFI Bonus":
			lapisDFI[lines[i].Date.Month()] += lines[i].Amount
		case "Lapis reward":
			lapis[lines[i].Date.Month()] += lines[i].Amount
		case "Referral reward":
			referral[lines[i].Date.Month()] += lines[i].Amount
		case "Bonus/Airdrop":
			airdrop[lines[i].Date.Month()] += lines[i].Amount
		case "Swapped in":
			swapped[lines[i].Date.Month()] += lines[i].Amount
		}
	}

	// get precision for specific coin
	_, precision, _ := getCurrencyOpts(lines[0].Cryptocurrency)
	// fill empty data with zeroes
	r := rewards{
		Staking:       fillSums(staking, precision),
		Confectionery: fillSums(confectionery, precision),
		LapisDFI:      fillSums(lapisDFI, precision),
		Lapis:         fillSums(lapis, precision),
		Referral:      fillSums(referral, precision),
	}
	return r
}

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, error) {
	var lines []line
	var csvLines []string

	// newlines need to be handled differently on windows
	switch runtime.GOOS {
	case "windows":
		csvLines = strings.Split(string(fileContents), "\r\n")
	default:
		csvLines = strings.Split(string(fileContents), "\n")
	}

	// loop through all lines (except headers)
	for _, csvLine := range csvLines[1:] {
		if csvLine != "" {
			// 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 {
				return nil, 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, nil
}