313 lines
10 KiB
Dart
313 lines
10 KiB
Dart
import 'dart:convert';
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import 'package:html/dom.dart' as dom;
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import 'package:html/parser.dart' as html;
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import '../../data/json_schedule_import.dart';
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import '../../domain/course.dart';
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import '../../domain/school_term.dart';
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import 'school_navigation_policy.dart';
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class UnsupportedSchoolLayout implements Exception {
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const UnsupportedSchoolLayout({
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this.code = 'layout_unknown',
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this.row,
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this.column,
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});
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final String code;
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final int? row, column;
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String get description => switch (code) {
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'origin_invalid' => '页面来源不符合学校课表要求',
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'payload_too_large' => '课表页面超过读取大小限制',
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'table_missing' => '未找到课表表格',
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'semester_missing' => '课表学期信息缺失',
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'row_count_invalid' => '课表时段行数不符合预期',
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'weekday_header_invalid' => '星期表头格式不符合预期',
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'row_cell_count_invalid' => '课表时段单元格不完整',
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'period_header_invalid' => '课表节次表头无法识别',
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'cell_id_invalid' => '课程单元格的星期或节次标识异常',
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'course_record_invalid' => '课程名称、教师或课程字段格式无法识别',
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'period_mismatch' => '课程节次与所在时段不一致',
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'weeks_invalid' => '上课周次格式无法识别',
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'unsafe_markup' => '课程单元格包含不支持的网页内容',
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'empty_timetable' => '课表尚无可识别的课程安排',
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_ => '学校课表格式暂不支持',
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};
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@override
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String toString() => '$description（$code），当前课表保持不变。请在反馈中附带学校HTML和日志。';
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}
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/// Reads the supplied graduate-system table as data; never executes its scripts.
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class SchoolPageAdapter {
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ImportDraft extract(
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String content,
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Uri origin, {
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CourseSource source = CourseSource.school,
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}) {
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try {
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if (!SchoolNavigationPolicy.isTimetable(origin) ||
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source == CourseSource.demo) {
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throw const UnsupportedSchoolLayout(code: 'origin_invalid');
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}
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if (utf8.encode(content).length > 2 * 1024 * 1024) {
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throw const UnsupportedSchoolLayout(code: 'payload_too_large');
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}
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final document = html.parse(content);
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final table = document.querySelector('#tbl');
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final selected = document.querySelector('#drpxq option[selected]');
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final term = selected?.attributes['value'];
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if (table == null) {
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throw const UnsupportedSchoolLayout(code: 'table_missing');
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}
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if (term == null ||
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!RegExp(r'^\d+$').hasMatch(term) ||
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selected!.text.trim().isEmpty) {
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throw const UnsupportedSchoolLayout(code: 'semester_missing');
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}
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final rows = table.querySelectorAll('tr');
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const weekdays = ['节次', '星期一', '星期二', '星期三', '星期四', '星期五', '星期六', '星期日'];
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if (rows.length != 6) {
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throw const UnsupportedSchoolLayout(code: 'row_count_invalid');
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}
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if (rows.first.children.length != 8) {
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throw const UnsupportedSchoolLayout(
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code: 'weekday_header_invalid',
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row: 0,
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);
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}
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for (var i = 0; i < 8; i++) {
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if (rows.first.children[i].text.trim() != weekdays[i]) {
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throw UnsupportedSchoolLayout(
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code: 'weekday_header_invalid',
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row: 0,
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column: i,
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);
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}
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}
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final courses = <String, Course>{};
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final ids = <String>{};
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const starts = [1, 3, 5, 7, 9];
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for (var row = 0; row < starts.length; row++) {
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final first = starts[row], last = first == 9 ? 11 : first + 1;
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final cells = rows[row + 1].children;
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if (cells.length != 8) {
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throw UnsupportedSchoolLayout(
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code: 'row_cell_count_invalid',
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row: row + 1,
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);
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}
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if (cells.first.id != 't0$first' ||
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cells.first.text.trim() != '$first-$last节') {
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throw UnsupportedSchoolLayout(
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code: 'period_header_invalid',
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row: row + 1,
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);
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}
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for (var day = 1; day <= 7; day++) {
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final cell = cells[day];
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if (cell.id != 't$day$first') {
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throw UnsupportedSchoolLayout(
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code: 'cell_id_invalid',
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row: row + 1,
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column: day,
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);
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}
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final List<String> lines;
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try {
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lines = _lines(cell);
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} on UnsupportedSchoolLayout catch (error) {
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throw UnsupportedSchoolLayout(
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code: error.code,
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row: row + 1,
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column: day,
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);
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}
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for (final line in lines) {
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final record = RegExp(
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r'^([A-Za-z0-9][A-Za-z0-9_.-]*)\s*/(.+?)/\s*(\d+(?:\.\d+)?)\s*/\s*(\d+(?:\.\d+)?)\s*/([^/]+)/([^/]+)周/(\d+)[~～-](\d+)节/(.*)$',
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).firstMatch(line);
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if (record == null) {
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throw UnsupportedSchoolLayout(
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code: 'course_record_invalid',
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row: row + 1,
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column: day,
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);
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}
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if (int.parse(record[7]!) != first ||
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int.parse(record[8]!) != last) {
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throw UnsupportedSchoolLayout(
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code: 'period_mismatch',
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row: row + 1,
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column: day,
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);
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}
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final code = record[1]!,
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name = record[2]!.trim(),
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teacher = record[5]!.trim(),
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rawRoom = record[9]!.trim(),
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room = rawRoom.isEmpty ? '教室待定' : rawRoom;
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if (name.isEmpty || teacher.isEmpty) {
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throw UnsupportedSchoolLayout(
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code: 'course_record_invalid',
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row: row + 1,
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column: day,
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);
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}
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final Set<int> weeks;
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try {
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weeks = _weeks(record[6]!);
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} on UnsupportedSchoolLayout catch (error) {
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throw UnsupportedSchoolLayout(
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code: error.code,
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row: row + 1,
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column: day,
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);
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}
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final identity = jsonEncode([
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term,
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code,
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name,
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teacher,
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room,
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day,
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first,
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last,
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]);
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final previous = courses[identity];
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final id =
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previous?.id ??
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'uestc-$term-$code-$day-$first-$last-${_hash(identity)}';
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if (previous == null && !ids.add(id)) {
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throw UnsupportedSchoolLayout();
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}
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courses[identity] = Course(
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id: id,
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name: name,
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teacher: teacher,
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room: room,
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weekday: day,
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startPeriod: first,
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endPeriod: last,
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weeks: {...?previous?.weeks, ...weeks},
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source: source,
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notes: rawRoom.isEmpty ? '学校未提供教室，请以学校最新安排为准并在公布后刷新课表。' : '',
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);
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}
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}
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}
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// An empty DOM can be an expired session or an incomplete response.
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if (courses.isEmpty) {
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throw const UnsupportedSchoolLayout(code: 'empty_timetable');
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}
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return ImportDraft(
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courses: List.unmodifiable(courses.values),
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explicitlyEmpty: false,
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source: source,
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parserVersion: 'uestc-graduate-html-v1',
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semesterLabel: selected.text.trim(),
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schoolTerm: SchoolTerm(int.parse(term)),
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);
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} on UnsupportedSchoolLayout {
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rethrow;
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} catch (_) {
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throw UnsupportedSchoolLayout();
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}
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}
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List<String> _lines(dom.Element cell) {
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final buffer = StringBuffer();
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void visit(dom.Node node) {
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if (node is dom.Text) {
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buffer.write(node.text);
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} else if (node is dom.Element) {
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if (node.localName == 'br') {
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buffer.write('\n');
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} else {
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if (node.localName == 'script' || node.localName == 'style') {
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throw const UnsupportedSchoolLayout(code: 'unsafe_markup');
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}
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for (final child in node.nodes) {
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visit(child);
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}
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}
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}
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}
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for (final node in cell.nodes) {
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visit(node);
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}
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return buffer
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.toString()
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.split('\n')
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.map((s) => s.trim())
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.where((s) => s.isNotEmpty)
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.toList();
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}
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Set<int> _weeks(String text) {
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final result = <int>{};
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for (final part in text.split(RegExp('[,，、]'))) {
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final range = RegExp(r'^\s*(\d+)(?:\s*[-~～]\s*(\d+))?\s*$')
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.firstMatch(part);
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if (range == null) {
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throw const UnsupportedSchoolLayout(code: 'weeks_invalid');
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}
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final first = int.parse(range[1]!),
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last = int.parse(range[2] ?? range[1]!);
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if (first < 1 || last > 30 || last < first) {
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throw const UnsupportedSchoolLayout(code: 'weeks_invalid');
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}
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result.addAll(List.generate(last - first + 1, (i) => first + i));
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}
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return result;
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}
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String _hash(String value) {
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var hash = 2166136261;
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for (final byte in utf8.encode(value)) {
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hash = ((hash ^ byte) * 16777619) & 0xffffffff;
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}
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return hash.toRadixString(16).padLeft(8, '0');
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}
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}
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class SchoolReader {
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SchoolReader(this.adapter);
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final SchoolPageAdapter adapter;
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Future<ImportDraft>? _pending;
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int _generation = 0;
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Uri? _origin;
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bool get busy => _pending != null;
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void invalidate() {
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_generation++;
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_pending = null;
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_origin = null;
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}
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Future<ImportDraft> read(Uri origin, Future<String> Function() getHtml) {
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if (!SchoolNavigationPolicy.isTimetable(origin) ||
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(_pending != null && origin != _origin)) {
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return Future.error(UnsupportedSchoolLayout());
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}
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if (_pending != null) return _pending!;
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final generation = _generation;
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_origin = origin;
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_pending = Future<ImportDraft>(() async {
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try {
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if (!SchoolNavigationPolicy.isTimetable(origin)) {
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throw UnsupportedSchoolLayout();
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}
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final content = await getHtml();
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if (generation != _generation) throw UnsupportedSchoolLayout();
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return adapter.extract(content, origin);
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} finally {
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if (generation == _generation) {
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_pending = null;
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_origin = null;
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}
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}
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});
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return _pending!;
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}
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}
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