package main

import (
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"strconv"
	"strings"
	"sync"
)
func writeDataToDisk(dest *string, board string, verlog *bool, post map[string]interface{}, cdnresbody []byte) {
	// Save the mediadata to file
	err := os.WriteFile(*dest + "/" + board + "-" + strconv.Itoa(int(post["tim"].(float64))) + post["ext"].(string), cdnresbody, 0664 )
	if err != nil {
		log.Fatal(err)
	} else if (*verlog) {
		log.Println("Successfully wrote image/video data to disk")
	}
}

func getPostData(post map[string]interface{}, board string, verlog *bool) []byte {
	// Check if post contains media (Video or Image)
	if post["ext"] != nil {
		cdnurlstr := "https://i.4cdn.org/" + board + "/" + strconv.Itoa(int(post["tim"].(float64))) + post["ext"].(string)
			
		// Requesting the media from CDN
		cdnres, err := http.Get(cdnurlstr)
		if err != nil {
			log.Fatal(err)
		}
		
		// Check if respons was valid
		if cdnres.StatusCode > 299 {
			log.Fatalf("Response failed with status code: %d and\n", cdnres.StatusCode)
		} else if (*verlog) {
			log.Println("Got image/video " + strconv.Itoa(int(post["tim"].(float64))) + post["ext"].(string) + " data")
		}
		
		// Read data form respons
		cdnresbody, err := io.ReadAll(cdnres.Body)
		cdnres.Body.Close()
		if err != nil {
			log.Fatal(err)
		} else if (*verlog) {
			log.Println("Successfully got data from responds body")
		}
		return cdnresbody

	} else if (*verlog) {
		log.Println("Post " + strconv.Itoa(int(post["no"].(float64))) + " didn't include a image or video")
	}
	return nil
}


func main ()  {
	// Setting up command flags
	wdpath, _ := os.Getwd();

	url := flag.String("u", "", "The url of the 4chan thread")
	
	dest := flag.String("o", wdpath, "Target dir of the conntent")

	verlog := flag.Bool("v", false, "Set logging to verbose")
	
	flag.Parse()
	
	// Check if flags are valid
	if *url == "" {
		fmt.Println("no thread URL provided")
		fmt.Println("use the -u=<Thread URL> flag to provid URL")
		os.Exit(1)
	}

	// Getting the boardname
	board := strings.Split(*url, "/")[3]

	// Get thread info from API
	res, err := http.Get(*url + ".json")
	if err != nil {
		log.Fatal(err)
	} else {
		log.Println("Got thread data")
	}

	// Check if API response is valid
	if res.StatusCode > 299 {
		log.Fatalf("Response failed with status code: %d and\n", res.StatusCode)
	} else if (*verlog) {
		log.Println("API response was ok")
	}
	
	//Geting the data from the response
	resbody, err := io.ReadAll(res.Body)
	res.Body.Close()
	if err != nil {
		log.Fatal(err)
	} else if (*verlog) {
		log.Println("Got body of API response")
	}
	
	// Var to save the JSON data 
	var jdata map[string]interface{}

	//Unmarshaling the API JSON respons
	if err := json.Unmarshal(resbody, &jdata); err != nil {
		log.Fatalln(err)
	} else if (*verlog) {
		log.Println("Unmarsheled API responsebody")	
	}
	

	var wg sync.WaitGroup

	// Iterating the posts from JSON data
	for _, v := range jdata["posts"].([]interface{}) {
		post := v.(map[string]interface{})
	
		wg.Add(1)
		
		go func() {
			defer wg.Done()
			if postdata := getPostData(post, board, verlog); postdata != nil {
				writeDataToDisk(dest, board, verlog, post, postdata)
			}
		}()	
	}

	wg.Wait()

	log.Println("DONE!!!")

}