Implement get_schedule

This should fix issue #140 (schedule tab only displays first three
classes). The new implementation of get_schedule is still a scraper
because the schedule does not seem to be exposed in the REST API, but it
is written in a cleaner and type-safe way.

package.json

@@ -49,6 +49,7 @@
     "tilt.js": "^1.2.1"
   },
   "devDependencies": {
+    "@types/jsdom": "^12.2.4",
     "@types/node-fetch": "^2.5.7",
     "typescript": "^4.1.2"
   }

src/scrape.ts

@@ -1,13 +1,21 @@
 import fetch from "node-fetch";
 import { URLSearchParams } from "url";
+import { JSDOM } from "jsdom";
 
 import type {
   Session,
   PDFFileInfo,
   ClassInfo,
   ClassDetails,
 } from "./types";
-import type { PDFFile, OverviewItem } from "./types-shared";
+
+import type {
+  PDFFile,
+  OverviewItem,
+  Schedule,
+  ScheduleItem
+} from "./types-shared";
+
 // Using `import type` with an enum disallows accessing the enum variants
 import { Quarter } from "./types-shared";
 
@@ -20,11 +28,156 @@ export async function get_student(
     const academics = await get_academics(session, student_oid, quarter_oids);
     const class_details = await Promise.all(academics.map(async class_info =>
       get_class_details(session, class_info)));
-    const overview = get_overview(class_details);
+    const overview = assemble_overview(class_details);
     return overview;
   });
 }
 
+/**
+ * Return an array containing all PDF files
+ */
+export async function get_pdf_files(
+  username: string, password: string
+): Promise<PDFFile[]> {
+  return await get_session(username, password, async session => {
+    const pdf_files = await list_pdf_files(session);
+    return await Promise.all(pdf_files.map(async ({ id, filename }) => ({
+      title: filename,
+      content: await download_pdf(session, id),
+    })));
+  });
+}
+
+export async function get_schedule(
+  username: string, password: string
+): Promise<Schedule> {
+  return await get_session(username, password, async session => {
+    const current_quarter = await get_current_quarter(session);
+    const initial_page = await (await fetch(
+      "https://aspen.cpsd.us/aspen/studentScheduleContextList.do?navkey=myInfo.sch.list", {
+        headers: {
+          "Cookie": `JSESSIONID=${session.session_id}`,
+        },
+      }
+    )).text();
+    // This is a term OID that is specific to the schedule view (not the same
+    // as the OIDs in the output of get_quarter_oids)
+    const [, term_oid] = new RegExp(
+      String.raw`<option value="(.+)">Q${current_quarter}</option>`
+    ).exec(initial_page) as RegExpExecArray;
+
+    const schedule_page = await (await fetch(
+      "https://aspen.cpsd.us/aspen/studentScheduleMatrix.do?" +
+      new URLSearchParams({
+        "navkey": "myInfo.sch.matrix",
+        "termOid": term_oid,
+      }), {
+        headers: {
+          "Cookie": `JSESSIONID=${session.session_id}`,
+        },
+      }
+    )).text();
+
+    const { window: { document } } = new JSDOM(schedule_page);
+
+    const rows = document.querySelectorAll(
+      "table[cellspacing='1'] > tbody > tr:not([class])"
+    );
+    // Get a matrix of the cells in the first three columns of the table, then
+    // transpose it to get a list of periods, a list of silver day classes
+    // (from Monday), and a list of black day classes (from Tuesday).
+    const [periods, silver_html, black_html] = transpose([...rows].map(row =>
+      [1, 2, 3].map(n =>
+        row.querySelector(`td:nth-child(${n})`)
+          ?.querySelector("td, th")?.innerHTML.trim() ?? ""
+      )
+    ));
+    const isScheduleItem =
+      function(x: ScheduleItem | undefined): x is ScheduleItem {
+        return x !== undefined;
+      };
+    const [black, silver] = [black_html, silver_html].map(arr =>
+      arr.map((x, i) => {
+        if (x) {
+          const lines = x.split("<br>");
+
+          // Decode HTML entities (https://stackoverflow.com/a/7394787)
+          const textarea = document.createElement("textarea");
+          const [id, name, teacher, room] = lines.map(line => {
+            textarea.innerHTML = line;
+            return textarea.value;
+          });
+          const aspenPeriod = periods[i];
+
+          return { id, name, teacher, room, aspenPeriod }
+        }
+      }).filter(isScheduleItem)
+    );
+
+    return { black, silver };
+  });
+}
+
+// https://stackoverflow.com/a/46805290
+function transpose<T>(matrix: T[][]): T[][] {
+  return matrix[0].map((col, i) => matrix.map(row => row[i]));
+}
+
+/**
+ * Get the current quarter (Q1, Q2, Q3, Q4). In the absence of the OID of a
+ * class (which can be fetched from get_academics), this function makes a
+ * request to get the OID of one class.
+ */
+async function get_current_quarter(
+  session: Session, class_info?: ClassInfo
+): Promise<Quarter> {
+  let oid: string;
+  if (class_info) {
+    ({ oid } = class_info);
+  } else {
+    const { student_oid } = await get_student_info(session);
+    [{ oid }] = await (await fetch(
+      "https://aspen.cpsd.us/aspen/rest/lists/academics.classes.list?fieldSetOid=fsnX2Cls++++++&" +
+      new URLSearchParams({
+        "selectedStudent": student_oid,
+        "customParams": "selectedYear|current;selectedTerm|all",
+      }), {
+        headers: {
+          "Cookie": `JSESSIONID=${session.session_id}`,
+        },
+      }
+    )).json();
+  }
+
+  const { currentTermIndex } = await (await fetch(
+    `https://aspen.cpsd.us/aspen/rest/studentSchedule/${oid}/gradeTerms`, {
+      headers: {
+        "Cookie": `JSESSIONID=${session.session_id}`,
+      },
+    }
+  )).json();
+
+  if (currentTermIndex + 1 in Quarter) {
+    return currentTermIndex + 1;
+  } else {
+    return 1;
+  }
+}
+
+/**
+ * Get a list of published reports (PDF files)
+ */
+async function list_pdf_files({ session_id }: Session): Promise<PDFFileInfo[]> {
+  const pdf_files: any[] = await (await fetch(
+    "https://aspen.cpsd.us/aspen/rest/reports", {
+      headers: {
+        "Cookie": `JSESSIONID=${session_id}`,
+      },
+    }
+  )).json();
+  return pdf_files.filter(({ contentTypeId }) => contentTypeId == "cttPdf");
+}
+
 /**
  * Get name and OID of student
  */
@@ -53,7 +206,7 @@ async function get_quarter_oids(
     }
   )).json();
   for (const { gradeTermId, oid } of terms) {
-    const [, quarter] = /^Q(\d)$/.exec(gradeTermId) || [];
+    const [, quarter] = /^Q(\d)$/.exec(gradeTermId) as RegExpExecArray;
     const quarter_num = parseInt(quarter) ?? -1;
     if (quarter_num in Quarter) {
       mapping.set(quarter_num, oid);
@@ -175,7 +328,7 @@ async function get_class_details(
   return { attendance, categories, ...class_info };
 }
 
-function get_overview(class_details: ClassDetails[]): OverviewItem[] {
+function assemble_overview(class_details: ClassDetails[]): OverviewItem[] {
   return class_details.map(({
     name,
     grades,
@@ -211,35 +364,6 @@ function get_overview(class_details: ClassDetails[]): OverviewItem[] {
   });
 }
 
-/**
- * Return an array containing all PDF files
- */
-export async function get_pdf_files(
-  username: string, password: string
-): Promise<PDFFile[]> {
-  return await get_session(username, password, async session => {
-    const pdf_files = await list_pdf_files(session);
-    return await Promise.all(pdf_files.map(async ({ id, filename }) => ({
-      title: filename,
-      content: await download_pdf(session, id),
-    })));
-  });
-}
-
-/**
- * Get a list of published reports (PDF files)
- */
-async function list_pdf_files({ session_id }: Session): Promise<PDFFileInfo[]> {
-  const pdf_files: any[] = await (await fetch(
-    "https://aspen.cpsd.us/aspen/rest/reports", {
-      headers: {
-        "Cookie": `JSESSIONID=${session_id}`,
-      },
-    }
-  )).json();
-  return pdf_files.filter(({ contentTypeId }) => contentTypeId == "cttPdf");
-}
-
 /**
  * Download a PDF file by ID (from list_pdf_files)
  */
@@ -267,11 +391,13 @@ async function get_session<T>(
   const login_page = await (await fetch(
     "https://aspen.cpsd.us/aspen/logon.do"
   )).text();
-  const [, session_id] = /sessionId='(.+)';/.exec(login_page) || [];
+  const [, session_id] = /sessionId='(.+)';/.exec(
+    login_page
+  ) as RegExpExecArray;
   const [, apache_token] =
     /name="org.apache.struts.taglib.html.TOKEN" value="(.+)"/.exec(
       login_page
-    ) || [];
+    ) as RegExpExecArray;
 
   // Submit login username, password, and session information
   const login_response = await (await fetch(