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"
	"sort"
)

const defid = "310118"

var wkey = map[string]string{
	"f":       "Feels Like Temperature",
	"h":       "Humidity",
	"p":       "Pressure",
	"t":       "Temperature",
	"v":       "Visibility",
	"wg":      "Wind Gust",
	"ws":      "Wind Speed",
	"pp":      "Precipitaton Probability",
	"uv":      "Max UV Index",
	"wd":      "Wind Direction",
	"wt":      "Weather Type",
	"AQIndex": "Air Quality",
}

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

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

type WeatherParam struct {
	AQIndex float64
	F       float64
	H       float64
	P       float64
	PP      float64
	UV      float64
	T       float64
	V       float64
	WD      string
	WG      float64
	WS      float64
	WT      float64
}

func main() {
	var j map[string]interface{}
	var id string

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

	// Use http.Client.Get as http.Get doesn't seem to handle TLS
	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, &j)
	if err != nil {
		log.Fatal(err)
	}

	// TODO: make this cleaner, perhaps by pre-speccing the structs
	days := j["BestFcst"].(map[string]interface{})["Forecast"].(map[string]interface{})["Location"].(map[string]interface{})["Day"].([]interface{})
	for _, d := range days {
		fmt.Printf("-----------------------------\n")
		fmt.Printf("Date: %v\n", d.(map[string]interface{})["@date"])
		fmt.Printf("\nDay weather:\n")
		prettyWeather(d.(map[string]interface{})["DayValues"].(map[string]interface{})["WeatherParameters"].(map[string]interface{}))
		fmt.Printf("\nNight weather:\n")
		prettyWeather(d.(map[string]interface{})["NightValues"].(map[string]interface{})["WeatherParameters"].(map[string]interface{}))

		fmt.Printf("\nTime steps:\n")
		timesteps := d.(map[string]interface{})["TimeSteps"].(map[string]interface{})["TimeStep"].([]interface{})
		for _, t := range timesteps {
			fmt.Printf("\nTime: %s\n", t.(map[string]interface{})["@time"])
			prettyWeather(t.(map[string]interface{})["WeatherParameters"].(map[string]interface{}))
		}
	}
}

func prettyWeather(w map[string]interface{}) {
	// TODO: choose what to show, and in what order, to have a compact output
	var keys []string
	for k, _ := range wkey {
		keys = append(keys, k)
	}
	sort.Strings(keys)

	for _, k := range keys {
		t, ok := w[k]
		if ok {
			fmt.Printf("%s: %v\n", wkey[k], t)
		}
	}
}