package main

import (
	"bytes"
	"encoding/csv"
	"encoding/json"
	"fmt"
	"net/http"
	"os"
	"strconv"
	"time"

	"git.ultraware.nl/Ultraware/util"
)

type iso8601 time.Time

func (d iso8601) String() string {
	return time.Time(d).String()
}

func (d *iso8601) UnmarshalJSON(data []byte) error {
	data = bytes.Trim(data, `"`)

	t, err := time.Parse(`2006-01-02T15:04:05-0700`, string(data))
	if err != nil {
		return err
	}

	*d = iso8601(t)
	return nil
}

type day struct {
	Summary struct {
		Date struct {
			ISO iso8601 `json:"iso8601"`
		} `json:"date"`
		MaxTemperature int `json:"max_temperature"`
		AvgTemperature int `json:"temperature"`
		MinTemperature int `json:"min_temperature"`
	} `json:"summary"`
}

type data struct {
	History struct {
		Days []day `json:"days"`
	} `json:"history"`
}

func main() {
	from := getNextDate()
	if from.After(time.Now()) {
		fmt.Println(`Nothing to get, exiting ...`)
		os.Exit(0)
	}

	to := from.AddDate(0, 0, 21)
	if to.After(time.Now()) {
		to = time.Now()
	}

	url := `https://api-ak.wunderground.com/api/d8585d80376a429e/history_` + from.Format(`20060102`) + to.Format(`20060102`) + `/lang:EN/units:english/bestfct:1/v:2.0/q/EHGG.json?showObs=0&ttl=120`
	fmt.Println(url)
	os.Exit(0)

	resp, err := http.Get(url)
	util.PanicOnErr(err)
	// f, err := os.Open(`data.json`)
	// util.PanicOnErr(err)

	var d data

	err = json.NewDecoder(resp.Body).Decode(&d)
	util.PanicOnErr(err)

	out, err := os.OpenFile(`weather.csv`, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0600)
	util.PanicOnErr(err)

	csvout := csv.NewWriter(out)
	for _, day := range d.History.Days {
		csvout.Write([]string{day.Summary.Date.ISO.String(), fToCString(day.Summary.MinTemperature), fToCString(day.Summary.AvgTemperature), fToCString(day.Summary.MaxTemperature)})
	}
	csvout.Flush()
}

func getNextDate() time.Time {
	f, err := os.Open(`weather.csv`)
	if err != nil {
		return time.Date(2019, 2, 1, 0, 0, 0, 0, time.Local)
	}

	csvf := csv.NewReader(f)
	var last []string
	for {
		row, err := csvf.Read()
		if err != nil {
			break
		}
		last = row
	}
	t, err := time.Parse(`2006-01-02 15:04:05.999999999 -0700 MST`, last[0])
	util.PanicOnErr(err)

	return t.AddDate(0, 0, 1)
}

func fToCString(temp int) string {
	return strconv.FormatFloat(float64(temp-32)/1.8, 'f', 1, 64)
}