package main

import (
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"encoding/json"
	"errors"
	"io/fs"
	"strconv"
)

var downloadKey string

func request(dirID string) []byte {
	req, err := http.NewRequest("GET", base+dirID, nil)
	if err != nil {
		log.Fatal(err)
	}

	req.Header.Add("Authorization", "Bearer "+downloadKey)

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		log.Fatal(err)
	}

	rt, err := io.ReadAll(resp.Body)
	if err != nil {
		log.Fatal(err)
	}
	resp.Body.Close()

	return rt
}

func traverse(j map[string]interface{}) {
	name := j["name"].(string)
	/* Internally stored as float64.
	Must be converted to int before string. */
	id := strconv.Itoa(int(j["id"].(float64)))
	fmt.Println(name, id)

	var files []map[string]interface{}
	var err error
	str := "folders/" + string(id) + "/files"
	fmt.Println(str)
	err = json.Unmarshal(request("folders/"+string(id)+"/files"),
		&files)
	if err != nil {
		log.Fatal(err)
	}

	for _, i := range files {
		for i, j := range i {
			fmt.Printf("%s %v\n", i, j)
		}
	}

	return
	err = os.Mkdir(name, 0777)
	if err != nil {
		log.Fatal(err)
	}

	_ = os.Chdir(name)
	defer os.Chdir("..")


}

// Traverse and download the contents of the Canvas API.
func main() {
	var set bool
	downloadKey, set = os.LookupEnv("CANKEY")
	if !set {
		log.Fatal("Set the environment variable CANKEY to persistently contain your Canvas account API key.")
	}

	_, err := os.Stat("root")
	if errors.Is(err, fs.ErrNotExist) {
		os.Mkdir("root", 0777)
	}
	err = os.Chdir("root")
	if err != nil {
		log.Fatal(err)
	}

	body := request("users/self/folders")

	var m []map[string]interface{}
	err = json.Unmarshal(body, &m)
	if err != nil {
		log.Fatal(err)
	}

	for _, i := range m {
		traverse(i)
	}
}