package main

// TODO: allow free-text lookups of place names, rather than ids
// TODO: decode weather type number
// TODO: split out met office specific stuff to separate module
// TODO: add other weather providers

import (
	"encoding/json"
	"flag"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
)

const defid = "310118"

type Response struct {
	BestFcst struct {
		Forecast struct {
			Location struct {
				Days []Day `json:"Day"`
			}
		}
	}
}

type Day struct {
	Date      string `json:"@date"`
	DayValues struct {
		WeatherParameters WeatherParams
	}
	NightValues struct {
		WeatherParameters WeatherParams
	}
	TimeSteps struct {
		TimeStep []struct {
			Time              string `json:"@time"`
			WeatherParameters WeatherParams
		}
	}
}

type WeatherParams struct {
	AQIndex int     // Air Quality
	F       float64 // Feels Like Temperature
	H       int     // Humidity
	P       int     // Pressure
	PP      int     // Precipitation Probability
	UV      int     // Max UV Index
	T       float64 // Temperature
	V       int     // Visibility
	WD      string  // Wind Direction
	WG      float64 // Wind Gust
	WS      float64 // Wind Speed
	WT      int     // Weather Type
}

func main() {
	var r Response
	var id string

	flag.Parse()
	if flag.NArg() > 0 {
		id = flag.Arg(0)
	} else {
		id = defid
	}

	client := &http.Client{Transport: &http.Transport{}}
	resp, err := client.Get("https://www.metoffice.gov.uk/public/data/PWSCache/BestForecast/Forecast/" + id + ".json?concise=true")
	if err != nil {
		log.Fatal(err)
	}
	defer resp.Body.Close()
	b, err := ioutil.ReadAll(resp.Body)
	err = json.Unmarshal(b, &r)
	if err != nil {
		log.Fatal(err)
	}

	for _, d := range r.BestFcst.Forecast.Location.Days {
		fmt.Printf("-----------------------------\n")
		fmt.Printf("%s\n", d.Date)
		prettyWeather("Day     ", d.DayValues.WeatherParameters)
		prettyWeather("Night   ", d.NightValues.WeatherParameters)

		for _, t := range d.TimeSteps.TimeStep {
			prettyWeather(t.Time, t.WeatherParameters)
		}
	}
}

func prettyWeather(t string, w WeatherParams) {
	fmt.Printf("%s  Type: %2d, Temp: %4.1f°C, Rain: %2d%%, Wind: %2.1fm/s\n", t, w.WT, w.T, w.PP, w.WS)
}