aplus/canvas.go

package main

import (
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/http"
	"net/http/cookiejar"
	"os"
	"strings"

	"golang.org/x/net/publicsuffix"
)

func initialize() {
	instance_url := os.Getenv("CANVAS_INSTANCE")
	if len(instance_url) == 0 {
		fmt.Println("The CANVAS_INSTANCE environment variable seems to be empty. Exiting.")
		os.Exit(1)
	}

	base_link = instance_url + "/api/v1"
	token = os.Getenv("CANVAS_API_KEY")
	if len(token) == 0 {
		fmt.Println("The CANVAS_API_KEY environment variable seems to be empty. Exiting.")
		os.Exit(1)
	}

	jar, _ := cookiejar.New(&cookiejar.Options{
		PublicSuffixList: publicsuffix.List,
	})

	client = http.Client{
		CheckRedirect: func(req *http.Request, via []*http.Request) error {
			if verbose {
				fmt.Println("Redirected to:", req.URL)
				fmt.Println(req.Cookies())
			}
			return nil
		},
		Jar: jar,
	}
}

func get_courses(token string, link string, client http.Client) []CanvasCourse {
	resp, err := client.Get(link)
	if err != nil {
		fmt.Println("Error performing GET request to get courses.")
		return nil
	}
	defer resp.Body.Close()
	body, _ := io.ReadAll(resp.Body)

	var canvas_courses []CanvasCourse
	err2 := json.Unmarshal(body, &canvas_courses)
	if err2 != nil {
		fmt.Println(err2)
		return nil
	}

	return canvas_courses
}

func init_aplus_toolid(course_id int) error {
	link := fmt.Sprintf("%s/courses/%d/external_tools?access_token=%s&search_term=aplus&include_parents=true", base_link, course_id, token)

	resp, err := client.Get(link)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	body, _ := io.ReadAll(resp.Body)

	var external_tools []ExternalTool
	err = json.Unmarshal(body, &external_tools)
	if err != nil && !strings.Contains(string(body), "\"unauthorized\"") {
		return err
	}

	for _, tool := range external_tools {
		if strings.Contains(tool.URL, ".aplusattendance.com/") {
			base_aplus_link = tool.URL
			external_tools_code = tool.ID
			return nil
		}
	}

	return errors.New("Could not find A+ link and tool ID")
}

func list_all_courses(onlyreturn bool) []CanvasCourse {
	all_courses := fmt.Sprintf("%s/courses?access_token=%s&enrollment_state=active&per_page=100", base_link, token)

	canvas_courses := get_courses(token, all_courses, client)

	if !onlyreturn {
		for _, course := range canvas_courses {
			fmt.Printf("%d, %s\n", course.ID%10000, course.Name)
		}

		return nil
	}

	return canvas_courses
}

func list_favorite_courses() {

	// course selection by user happens below
	favorites := fmt.Sprintf("%s/users/self/favorites/courses?access_token=%s&per_page=100", base_link, token)

	canvas_courses := get_courses(token, favorites, client)

	for _, course := range canvas_courses {
		fmt.Printf("%d, %s\n", course.ID%10000, course.Name)
	}
}