package main

import (
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"strings"
)

// downloadCategory downloads the given category from celestrack
func downloadCategory(categoryName string) {

	// define where to download the TLEs from
	base := "https://celestrak.com/NORAD/elements/"
	downloadURL := fmt.Sprintf("%s%s.txt", base, categoryName)

	// define the HTTP GET request and make it
	resp, err := http.Get(downloadURL)
	if err != nil {
		log.Printf("Could not download %s", categoryName)
	}
	defer resp.Body.Close()

	// read the respose from the GET request
	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		log.Printf("Could not read the category %s", categoryName)
	}

	// write the response to the corresponding file
	filename := fmt.Sprintf("data/%s.txt", categoryName)
	f, err := os.Create(filename) // creating the file
	if err != nil {
		fmt.Printf("Could not create file data/%s.txt", categoryName)
	}
	_, err = f.WriteString(string(body)) // writing the TLE to the file
	if err != nil {
		fmt.Printf("Could not write to file data/%s.txt", categoryName)
	}
}

// dumpall dumps all the categories into the data folder
func dumpall() {
	// read the name of the categories from the categories.txt file and write
	// the result to the categories slice
	content, err := ioutil.ReadFile("categories.txt")
	if err != nil {
		log.Printf("%s\n", "could not read categories.txt file!")
	}
	lines := strings.Split(string(content), "\n")

	for _, line := range lines {
		if line != "" {
			categories = append(categories, line)
		}
	}

	// download all the categories to the data/<category name> directory
	for _, category := range categories {
		log.Printf("downloading %s... ", category)
		downloadCategory(category)
	}
}