package main

import (
	"encoding/json"
	"flag"
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"strings"

	"net/http"

	TLE "git.darknebu.la/Satellite/TLE"
	"github.com/gorilla/mux"
)

var (
	categories []string
	port       int
)

func main() {
	initFlags()
	r := mux.NewRouter()

	r.HandleFunc("/", indexHandler)
	r.HandleFunc("/dumpall", dumpallHandler)
	r.HandleFunc("/{station}/{name}", getHandler)

	log.Fatal(http.ListenAndServe(fmt.Sprintf(":%d", port), r))
}

func initFlags() {
	flag.IntVar(&port, "p", 8080, "the port the server should listen on")
	flag.Parse()
}

func indexHandler(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintf(w, "%s", "<h1>Hello World</h1>")
}

// dumpallHandler dumps all categories
func dumpallHandler(w http.ResponseWriter, r *http.Request) {
	log.Println("[ ] Dumping all TLEs")

	// 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", "could not read categories.txt file!")
	}
	lines := strings.Split(string(content), "\n")

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

	// download all the categories to the data/<category name> directory
	for _, category := range categories {
		downloadCategory(category)
	}

	log.Println("[+] Done dumping all TLEs")
}

// 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)
	}
}

// get Handler returns the specified TLE
func getHandler(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)

	// read the TLEs from the categories file
	//content, err := ioutil.ReadFile("categories.txt")
	//if err != nil {
	//	log.Println("Could note read categories.txt")
	//}

	// handle the response according to the query parameter "format"
	// if ?format=json is given, return
	if r.URL.Query().Get("format") == "json" {
		w.Header().Set("Content-Type", "application/json")

		RawTLE := `ISS (ZARYA)             
1 25544U 98067A   19229.39083552  .00000228  00000-0  11917-4 0  9993
2 25544  51.6447  57.6210 0007373 294.0868 138.8050 15.50381554184754`

		JSONTLE, err := TLE.NewTLE(RawTLE)
		if err != nil {
			fmt.Println(err)
		}

		// convert the TLE to json
		b, err := json.MarshalIndent(JSONTLE, "", " ")
		if err != nil {
			fmt.Println("error: ", err)
		}
		fmt.Fprintf(w, string(b))
		//fmt.Fprintf(w, "{\"response\": \"Getting the TLE for %s/%s as json\"}", vars["station"], vars["name"])
	} else {
		fmt.Fprintf(w, "Getting the TLE for %s/%s raw", vars["station"], vars["name"])
	}

}