use the Canvas API to get A+ tool ID and URL

Was previously hardcoded.

5 files changed, 43 insertions, 6 deletions

diff --git a/README.md b/README.md
index 99780c3..93917e4 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 This is an cli utility initially created for students at Florida Polytechnic University to submit their aplus codes. 
 In time, we intend to generalize this utility to all universities.
-In the meantime however, any students from other universities wishing to use the utility may change the base_link and external_tools_code (you see this in the URL when you navigate to Aplus attendance within your course) variables.
+In the meantime however, any students from other universities wishing to use the utility may change the instance_url (the main URL you see before the / when you use Canvas) variables.
 
 ## Usage
 
diff --git a/aplus.go b/aplus.go
index a8d4daf..51a5a10 100644
--- a/aplus.go
+++ b/aplus.go
@@ -7,6 +7,7 @@ import (
         "io"
         "net/http"
         "net/url"
+        "os"
         "strings"
 )
 
@@ -60,6 +61,12 @@ func submit_code(course_code int, attendance_code string) {
 }
 
 func launch_aplus(course_code int) string {
+        err := init_aplus_toolid(course_code)
+        if err != nil {
+                fmt.Println("Failed to get A+ base URL and tool ID")
+                os.Exit(1)
+        }
+
         aplus_link := fmt.Sprintf("%s/courses/%d/external_tools/sessionless_launch?id=%d&access_token=%s",
                 base_link, course_code, external_tools_code, token)
         aplus := get_aplus(token, aplus_link, client)
diff --git a/canvas.go b/canvas.go
index df5f94c..5a43999 100644
--- a/canvas.go
+++ b/canvas.go
@@ -2,20 +2,21 @@ package main
 
 import (
         "encoding/json"
+        "errors"
         "fmt"
         "io"
         "net/http"
         "net/http/cookiejar"
         "os"
+        "strings"
 
         "golang.org/x/net/publicsuffix"
 )
 
 func initialize() {
-        base_link = "https://floridapolytechnic.instructure.com/api/v1"
-        base_aplus_link = "https://floridapoly.aplusattendance.com/canvas"
+        instance_url := "https://floridapolytechnic.instructure.com"
+        base_link = instance_url + "/api/v1"
         token = os.Getenv("CANVAS_API_KEY")
-        external_tools_code = 913
         jar, _ := cookiejar.New(&cookiejar.Options{
                 PublicSuffixList: publicsuffix.List,
         })
@@ -49,6 +50,31 @@ func get_courses(token string, link string, client http.Client) []CanvasCourse {
         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 == "" {
+                        base_aplus_link = tool.URL
+                        external_tools_code = tool.ID
+                }
+        }
+
+        return errors.New("Could not find A+ link and tool ID")
+}
+
 func list_all_courses() {
         all_courses := fmt.Sprintf("%s/courses?access_token=%s&per_page=100", base_link, token)
 
diff --git a/main.go b/main.go
index b6b1e1a..9386b46 100644
--- a/main.go
+++ b/main.go
@@ -9,9 +9,7 @@ import (
 )
 
 var base_link string
-var base_aplus_link string
 var token string
-var external_tools_code int
 var client http.Client
 
 func main() {
diff --git a/structs.go b/structs.go
index bf75787..2da2899 100644
--- a/structs.go
+++ b/structs.go
@@ -54,3 +54,9 @@ type Enrollment struct {
         EnrollmentState                string `json:"enrollment_state"`
         LimitPrivilegesToCourseSection bool   `json:"limit_privileges_to_course_section"`
 }
+
+type ExternalTool struct {
+        ID     int    `json:"id"`
+        URL    string `json:"url"`
+        Status string `json:"status"`
+}