package main

import (
	"bufio"
	"encoding/csv"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"os"
	"strconv"
	"time"
)

type ActivityLine struct {
	Date             time.Time
	CaloriesEstimate uint64
}

func main() {
	var csvPathArg string
	var endDateArg string
	var startDateArg string
	var outputPath string
	flag.StringVar(&csvPathArg, "csv", "heat.csv", "Specify csv path, default is heat.csv.")
	flag.StringVar(&outputPath, "o", "heatmap.svg", "Specify output path, default is heatmeap.svg.")
	flag.StringVar(&startDateArg, "s", "", "Specify start date (2006-01-02). Default is 1 year previous to end date.")
	flag.StringVar(&endDateArg, "e", "", "Specify end date (2006-01-02). Default is today.")

	flag.Parse()

	endDate := time.Date(time.Now().Year(), time.Now().Month(), time.Now().Day(), 0, 0, 0, 0, time.Local)
	if endDateArg != "" {
		var err error
		endDate, err = time.ParseInLocation("2006-01-02", endDateArg, time.Local)
		if err != nil {
			fmt.Println("failed to parse end time")
			return
		}
	}
	start := time.Date(endDate.Year()-1, endDate.Month(), endDate.Day(), 0, 0, 0, 0, time.Local)
	if startDateArg != "" {
		var err error
		start, err = time.ParseInLocation("2006-01-02", startDateArg, time.Local)
		if err != nil {
			fmt.Println("failed to parse start time")
			return
		}
	}

	csvFile, _ := os.Open(csvPathArg)
	reader := csv.NewReader(bufio.NewReader(csvFile))
	var length int = 17
	var days = make(map[time.Time]uint64)
	for {
		line, error := reader.Read()
		if error == io.EOF {
			break
		} else if error != nil {
			log.Fatal(error)
		}
		thisTime, error := time.Parse("2006-01-02", line[0])
		thisTime = time.Date(thisTime.Year(), thisTime.Month(), thisTime.Day(), 0, 0, 0, 0, time.Local)
		if error != nil {
			fmt.Println(error)
			break
		}
		cals, error := strconv.ParseUint(line[1], 10, 64)
		if error != nil {
			break
		}

		days[thisTime] = days[thisTime] + cals
	}
	svg := "<svg width=\"960\" height=\"152\"><g transform=\"translate(29.5,24)\"><g fill=\"none\" stroke=\"#ccc\">"
	datePointer := start
	var week int = 0

	var monthChange = false
	var monthLabelSpots = make(map[string]int)
	for {

		var calsOnDay = days[datePointer]

		if calsOnDay > 0 {
			svg = fmt.Sprintf("%s\n<rect width=\"%v\" height=\"%v\" x=\"%v\" y=\"%v\" fill=\"#00FF00\"></rect>", svg, length, length, week*length, length*int(datePointer.Weekday()))
		} else {
			svg = fmt.Sprintf("%s\n<rect width=\"%v\" height=\"%v\" x=\"%v\" y=\"%v\" ></rect>", svg, length, length, week*length, length*int(datePointer.Weekday()))
		}
		datePointer = datePointer.Add(time.Hour * 24)

		if datePointer.After(endDate) {
			break
		}
		if datePointer.Day() == 1 {
			monthChange = true
		}
		if datePointer.Weekday() == time.Sunday {
			week++
			if monthChange {
				monthLabelSpots[datePointer.Month().String()] = week * length
				monthChange = false
			}
		}
	}
	svg = fmt.Sprintf("%s\n</g></g>", svg)

	//day of week labels
	//note to self, text position is the bottom left of the _baseline_ of text
	svg = fmt.Sprintf("%s<g transform=\"translate(6, 24)\">", svg)
	svg = fmt.Sprintf("%s<text x=\"0\" y=\"%v\">Mon</text>", svg, length*2-(length/3))
	svg = fmt.Sprintf("%s<text x=\"0\" y=\"%v\">Wed</text>", svg, length*4-(length/3))
	svg = fmt.Sprintf("%s<text x=\"0\" y=\"%v\">Fri</text>", svg, length*6-(length/3))
	svg = fmt.Sprintf("%s</g>", svg)

	//month labels
	svg = fmt.Sprintf("%s<g transform=\"translate(30,14)\">", svg)
	for monthName := range monthLabelSpots {
		svg = fmt.Sprintf("%s<text x=\"%v\" y=\"0\">%v</text>", svg, monthLabelSpots[monthName], monthName[:3])
	}
	svg = fmt.Sprintf("%s</g>", svg)

	svg = fmt.Sprintf("%s</svg>", svg)
	ioutil.WriteFile(outputPath, []byte(svg), 0644)
}