client.go

package apixu

import (
	"encoding/json"
	"errors"
	"io/ioutil"
	"net/http"
	"net/url"
)

const (
	apiVersion = "v1"
	apiBaseURL = "http://api.apixu.com/" + apiVersion + "/"

	currentPath  = "current.json"
	forecastPath = "forecast.json"
	historyPath  = "history.json"
	searchPath   = "search.json"
)

// OptionalParam describes optional query parameters used in client methods.
type OptionalParam struct {
	Name  string
	Value string
}

// Location describes essential data of the matched location.
type Location struct {
	Name           string  `json:"name"`
	Region         string  `json:"region"`
	Country        string  `json:"country"`
	Lat            float64 `json:"lat"`
	Lon            float64 `json:"lon"`
	TzID           string  `json:"tz_id"`
	LocaltimeEpoch int     `json:"localtime_epoch"`
	Localtime      string  `json:"localtime"`
}

// Current describes realtime weather information.
type Current struct {
	LastUpdatedEpoch int     `json:"last_updated_epoch"`
	LastUpdated      string  `json:"last_updated"`
	TempC            float64 `json:"temp_c"`
	TempF            float64 `json:"temp_f"`
	IsDay            int     `json:"is_day"`
	Condition        struct {
		Text string `json:"text"`
		Icon string `json:"icon"`
		Code int    `json:"code"`
	} `json:"condition"`
	WindMph    float64 `json:"wind_mph"`
	WindKph    float64 `json:"wind_kph"`
	WindDegree int     `json:"wind_degree"`
	WindDir    string  `json:"wind_dir"`
	PressureMb float64 `json:"pressure_mb"`
	PressureIn float64 `json:"pressure_in"`
	PrecipMm   float64 `json:"precip_mm"`
	PrecipIn   float64 `json:"precip_in"`
	Humidity   int     `json:"humidity"`
	Cloud      int     `json:"cloud"`
	FeelslikeC float64 `json:"feelslike_c"`
	FeelslikeF float64 `json:"feelslike_f"`
	VisKm      float64 `json:"vis_km"`
	VisMiles   float64 `json:"vis_miles"`
}

// Forecast describes astronomy data.
type Forecast struct {
	Forecastday []struct {
		Date      string `json:"date"`
		DateEpoch int    `json:"date_epoch"`
		Day       struct {
			MaxtempC      float64 `json:"maxtemp_c"`
			MaxtempF      float64 `json:"maxtemp_f"`
			MintempC      float64 `json:"mintemp_c"`
			MintempF      float64 `json:"mintemp_f"`
			AvgtempC      float64 `json:"avgtemp_c"`
			AvgtempF      float64 `json:"avgtemp_f"`
			MaxwindMph    float64 `json:"maxwind_mph"`
			MaxwindKph    float64 `json:"maxwind_kph"`
			TotalprecipMm float64 `json:"totalprecip_mm"`
			TotalprecipIn float64 `json:"totalprecip_in"`
			AvgvisKm      float64 `json:"avgvis_km"`
			AvgvisMiles   float64 `json:"avgvis_miles"`
			Avghumidity   float64 `json:"avghumidity"`
			Condition     struct {
				Text string `json:"text"`
				Icon string `json:"icon"`
				Code int    `json:"code"`
			} `json:"condition"`
			Uv float64 `json:"uv"`
		} `json:"day"`
		Astro struct {
			Sunrise  string `json:"sunrise"`
			Sunset   string `json:"sunset"`
			Moonrise string `json:"moonrise"`
			Moonset  string `json:"moonset"`
		} `json:"astro"`
		Hour []struct {
			TimeEpoch int     `json:"time_epoch"`
			Time      string  `json:"time"`
			TempC     float64 `json:"temp_c"`
			TempF     float64 `json:"temp_f"`
			IsDay     int     `json:"is_day"`
			Condition struct {
				Text string `json:"text"`
				Icon string `json:"icon"`
				Code int    `json:"code"`
			} `json:"condition"`
			WindMph      float64 `json:"wind_mph"`
			WindKph      float64 `json:"wind_kph"`
			WindDegree   int     `json:"wind_degree"`
			WindDir      string  `json:"wind_dir"`
			PressureMb   float64 `json:"pressure_mb"`
			PressureIn   float64 `json:"pressure_in"`
			PrecipMm     float64 `json:"precip_mm"`
			PrecipIn     float64 `json:"precip_in"`
			Humidity     int     `json:"humidity"`
			Cloud        int     `json:"cloud"`
			FeelslikeC   float64 `json:"feelslike_c"`
			FeelslikeF   float64 `json:"feelslike_f"`
			WindchillC   float64 `json:"windchill_c"`
			WindchillF   float64 `json:"windchill_f"`
			HeatindexC   float64 `json:"heatindex_c"`
			HeatindexF   float64 `json:"heatindex_f"`
			DewpointC    float64 `json:"dewpoint_c"`
			DewpointF    float64 `json:"dewpoint_f"`
			WillItRain   int     `json:"will_it_rain"`
			ChanceOfRain string  `json:"chance_of_rain"`
			WillItSnow   int     `json:"will_it_snow"`
			ChanceOfSnow string  `json:"chance_of_snow"`
			VisKm        float64 `json:"vis_km"`
			VisMiles     float64 `json:"vis_miles"`
		} `json:"hour"`
	} `json:"forecastday"`
}

// CurrentWeather describes data returned by current.
type CurrentWeather struct {
	Location Location `json:"location"`
	Current  Current  `json:"current"`
}

// ForecastWeather describes data returned by forecast.
type ForecastWeather struct {
	Location Location `json:"location"`
	Current  Current  `json:"current"`
	Forecast Forecast `json:"forecast"`
}

// HistoryWeather describes data returned by history.
type HistoryWeather struct {
	Location Location `json:"location"`
	Forecast Forecast `json:"forecast"`
}

// MatchingCities describes data returned by search.
type MatchingCities []struct {
	ID      int     `json:"id"`
	Name    string  `json:"name"`
	Region  string  `json:"region"`
	Country string  `json:"country"`
	Lat     float64 `json:"lat"`
	Lon     float64 `json:"lon"`
	URL     string  `json:"url"`
}

type errorResponse struct {
	Error struct {
		Code    int    `json:"code"`
		Message string `json:"message"`
	} `json:"error"`
}

// Client describes apixu api client.
type Client struct {
	apiKey string
}

// Current returns CurrentWeather obj representing current weather status.
func (client *Client) Current(q string, optionalParams ...OptionalParam) (*CurrentWeather, error) {
	url, err := client.getURL(currentPath, q, optionalParams...)

	if err != nil {
		return nil, err
	}

	body, err := request(url)

	if err != nil {
		return nil, err
	}

	var currentWeather CurrentWeather

	if err := json.Unmarshal(body, &currentWeather); err != nil {
		return nil, err
	}

	return &currentWeather, nil
}

// Forecast returns ForecastWeather obj representing forecast status.
func (client *Client) Forecast(q string, days int, optionalParams ...OptionalParam) (*ForecastWeather, error) {
	optionalParams = append(optionalParams, OptionalParam{"days", string(days)})
	url, err := client.getURL(forecastPath, q, optionalParams...)

	if err != nil {
		return nil, err
	}

	body, err := request(url)

	if err != nil {
		return nil, err
	}

	var forecastWeather ForecastWeather

	if err := json.Unmarshal(body, &forecastWeather); err != nil {
		return nil, err
	}

	return &forecastWeather, nil
}

// History returns HistoryWeather obj representing history status.
func (client *Client) History(q string, dt string, optionalParams ...OptionalParam) (*HistoryWeather, error) {
	optionalParams = append(optionalParams, OptionalParam{"dt", dt})
	url, err := client.getURL(historyPath, q, optionalParams...)

	if err != nil {
		return nil, err
	}

	body, err := request(url)

	if err != nil {
		return nil, err
	}

	var historyWeather HistoryWeather

	if err := json.Unmarshal(body, &historyWeather); err != nil {
		return nil, err
	}

	return &historyWeather, nil
}

// Search returns MatchingCities obj representing a list of matched cities.
func (client *Client) Search(q string) (*MatchingCities, error) {
	url, err := client.getURL(searchPath, q)

	if err != nil {
		return nil, err
	}

	body, err := request(url)

	if err != nil {
		return nil, err
	}

	var matchingCities MatchingCities

	if err := json.Unmarshal(body, &matchingCities); err != nil {
		return nil, err
	}

	return &matchingCities, nil
}

func (client *Client) getURL(path string, q string, optionalParams ...OptionalParam) (string, error) {
	baseURL, err := url.Parse(apiBaseURL)

	if err != nil {
		return "", err
	}

	pathURL, err := url.Parse(path)

	if err != nil {
		return "", err
	}

	URL := baseURL.ResolveReference(pathURL)
	query := URL.Query()
	query.Set("key", client.apiKey)
	query.Set("q", q)

	// Set optional params.
	for _, param := range optionalParams {
		query.Set(param.Name, param.Value)
	}

	URL.RawQuery = query.Encode()

	return URL.String(), nil
}

// NewClient returns a new client reference.
func NewClient(apiKey string) *Client {
	client := &Client{apiKey: apiKey}
	return client
}

func request(url string) ([]byte, error) {
	response, err := http.Get(url)

	if err != nil {
		return nil, err
	}

	defer response.Body.Close()

	body, err := ioutil.ReadAll(response.Body)

	// Validate response.
	if response.StatusCode != 200 {
		var errorJSON errorResponse

		if err := json.Unmarshal(body, &errorJSON); err != nil {
			return nil, err
		}

		return nil, errors.New(errorJSON.Error.Message)
	}

	return body, err
}