// GoWeather
//
// Copyright (c) 2023 Helmut Kaczmarek <code@helmutkaczmarek.de>
//
// My first small attempt in the programming language Go.
//
// GoWeather is a tiny command line program that queries the current
// weather in a specified city via OpenWeatherMap's API and displays the
// result in the terminal window.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package main

import (
	"encoding/json"
	"fmt"
	"net/http"
)

// Structure to store the weather data from the API
type WeatherData struct {
	Name string `json:"name"`
	Main struct {
		Temp float64 `json:"temp"`
	} `json:"main"`
	Weather []struct {
		Description string `json:"description"`
	} `json:"weather"`
	Cod     int    `json:"cod"`
	Message string `json:"message"`
}

func main() {
	// Put your OpenWeatherMap API key and city ID here
	apiKey := "API_KEY"
	city := "CITY_ID"

	// Generate the URL for the API call
	url := fmt.Sprintf("http://api.openweathermap.org/data/2.5/weather?id=%s&appid=%s&units=metric", city, apiKey)

	// Send the API call and get the response
	response, err := http.Get(url)
	if err != nil {
		fmt.Println("Error getting the data:", err)
		return
	}
	defer response.Body.Close()

	// Decode the JSON response into the WeatherData structure
	var data WeatherData
	if err := json.NewDecoder(response.Body).Decode(&data); err != nil {
		fmt.Println("Error decoding data:", err)
		return
	}

	// Check for API error codes and display error messages if there are any
	if data.Cod == 401 {
		fmt.Println("Error: Invalid API key.")
		fmt.Println("API error message:", data.Message)
		return
	}

	if data.Cod != 200 {
		fmt.Println("Error: Request failed.")
		fmt.Println("API error message:", data.Message)
		return
	}

	// Display the weather data in the terminal window
	fmt.Printf("Weather in %s\n", data.Name)
	fmt.Println("===============================")
	fmt.Printf("Temperature: %.1f °C\n", data.Main.Temp)
	if len(data.Weather) > 0 {
		fmt.Printf("Description: %s\n", data.Weather[0].Description)
	}
	fmt.Println("===============================")

	// Wait for the enter key before exiting the program
	fmt.Print("Press Enter to exit GoWeather...")
	fmt.Scanln()
}