import assert from 'node:assert/strict';
import { describe, it } from 'node:test';
import { chunkRange, collectLessonLog, hasContent, lessonLogText } from '../src/core/untis-history.ts';
import type { UntisClient, UntisLesson, UntisTimetable, UntisTopic } from '../src/core/untis.ts';

/**
 * The class register, read backwards. The client is a stand-in: what is under
 * test is which periods are asked about and how the two halves are merged, not
 * the JSON-RPC layer, which test/untis.test.ts already covers.
 */

function lesson(overrides: Partial<UntisLesson> & { periodId: number; lessonId: number; date: string }): UntisLesson {
	return {
		start: '08:00',
		end: '08:45',
		statuses: ['REGULAR'],
		cancelled: false,
		changed: false,
		subjects: [{ name: 'DE', longName: 'Deutsch' }],
		teachers: [{ name: 'MEI', longName: 'Meier' }],
		rooms: [],
		classes: [],
		replaced: { subjects: [], teachers: [], rooms: [] },
		notes: {},
		homework: [],
		online: false,
		...overrides,
	};
}

function client(lessons: UntisLesson[], topics: Record<number, UntisTopic[]>, seen?: { periods: number[] }): UntisClient {
	return {
		async timetable(from: string, to: string): Promise<UntisTimetable> {
			const days = [...new Set(lessons.map((entry) => entry.date))].filter((date) => date >= from && date <= to);
			return { from, to, days: days.map((date) => ({ date, lessons: lessons.filter((l) => l.date === date), holidays: [] })) };
		},
		async lessonTopics(periodId: number): Promise<UntisTopic[]> {
			seen?.periods.push(periodId);
			const found = topics[periodId];
			if (!found) throw new Error(`period ${periodId} not found`);
			return found;
		},
	} as unknown as UntisClient;
}

describe('chunkRange', () => {
	it('is one window for a short range', () => {
		assert.deepEqual(chunkRange('2026-09-01', '2026-09-30'), [['2026-09-01', '2026-09-30']]);
	});

	it('splits a school year into windows the timetable call accepts', () => {
		const chunks = chunkRange('2026-01-01', '2026-12-31');
		assert.ok(chunks.length > 1);
		assert.equal(chunks[0]![0], '2026-01-01');
		assert.equal(chunks.at(-1)![1], '2026-12-31');
		// No gaps and no overlaps: every day belongs to exactly one window.
		for (let i = 1; i < chunks.length; i++) {
			const previousEnd = new Date(`${chunks[i - 1]![1]}T12:00:00Z`).getTime();
			const start = new Date(`${chunks[i]![0]}T12:00:00Z`).getTime();
			assert.equal(start - previousEnd, 86_400_000);
		}
	});
});

describe('collectLessonLog', () => {
	it('asks each series once, about its latest period', async () => {
		// getLessonTopic2017 answers with the lessons *before* the period given,
		// so the newest period of a series reaches all of its history and one
		// call per series covers a term.
		const seen = { periods: [] as number[] };
		const lessons = [
			lesson({ periodId: 1, lessonId: 100, date: '2026-09-01' }),
			lesson({ periodId: 2, lessonId: 100, date: '2026-09-08' }),
			lesson({ periodId: 3, lessonId: 200, date: '2026-09-09' }),
		];
		const topics = {
			2: [{ text: 'Erörterung', periodId: 1, date: '2026-09-01', start: '08:00', end: '08:45' }],
			3: [{ text: 'Netze', periodId: 3, date: '2026-09-09', start: '08:00', end: '08:45' }],
		};
		await collectLessonLog(client(lessons, topics, seen), { from: '2026-09-01', to: '2026-09-30' });
		assert.deepEqual(seen.periods.sort(), [2, 3]);
	});

	it('merges a topic onto the period it belongs to', async () => {
		const lessons = [lesson({ periodId: 1, lessonId: 100, date: '2026-09-01' }), lesson({ periodId: 2, lessonId: 100, date: '2026-09-08' })];
		const topics = { 2: [{ text: 'Erörterung', periodId: 1, date: '2026-09-01', start: '08:00', end: '08:45' }] };
		const log = await collectLessonLog(client(lessons, topics), { from: '2026-09-01', to: '2026-09-30' });
		assert.deepEqual(log.entries.map((entry) => [entry.periodId, entry.topic]), [[1, 'Erörterung']]);
	});

	it('keeps a lesson that has only a teacher note, and drops the empty ones', async () => {
		const lessons = [
			lesson({ periodId: 1, lessonId: 100, date: '2026-09-01', notes: { info: 'LK am 20.09.' } }),
			lesson({ periodId: 2, lessonId: 100, date: '2026-09-08' }),
		];
		const log = await collectLessonLog(client(lessons, { 2: [] }), { from: '2026-09-01', to: '2026-09-30' });
		assert.deepEqual(log.entries.map((entry) => entry.periodId), [1]);
		assert.equal(log.periodsSeen, 2);
	});

	it('skips cancelled periods, which taught nothing', async () => {
		const lessons = [lesson({ periodId: 1, lessonId: 100, date: '2026-09-01', cancelled: true, notes: { info: 'Entfall' } })];
		const log = await collectLessonLog(client(lessons, {}), { from: '2026-09-01', to: '2026-09-30' });
		assert.equal(log.periodsSeen, 0);
		assert.deepEqual(log.entries, []);
	});

	it('matches a subject on either its code or its long name', async () => {
		const lessons = [
			lesson({ periodId: 1, lessonId: 100, date: '2026-09-01', notes: { info: 'x' } }),
			lesson({ periodId: 2, lessonId: 200, date: '2026-09-01', subjects: [{ name: 'LF07', longName: 'Lernfeld 7' }], notes: { info: 'y' } }),
		];
		const byCode = await collectLessonLog(client(lessons, {}), { from: '2026-09-01', to: '2026-09-30', subject: 'lf07' });
		assert.deepEqual(byCode.entries.map((entry) => entry.periodId), [2]);
		const byName = await collectLessonLog(client(lessons, {}), { from: '2026-09-01', to: '2026-09-30', subject: 'deutsch' });
		assert.deepEqual(byName.entries.map((entry) => entry.periodId), [1]);
	});

	it('records a refused series rather than losing the whole term', async () => {
		const lessons = [
			lesson({ periodId: 1, lessonId: 100, date: '2026-09-01', notes: { info: 'bleibt' } }),
			lesson({ periodId: 2, lessonId: 200, date: '2026-09-02', notes: { info: 'auch' } }),
		];
		// Period 2's series throws; period 1's does not.
		const log = await collectLessonLog(client(lessons, { 1: [] }), { from: '2026-09-01', to: '2026-09-30' });
		assert.equal(log.failures.length, 1);
		assert.equal(log.entries.length, 2);
	});

	it('is newest first', async () => {
		const lessons = [
			lesson({ periodId: 1, lessonId: 100, date: '2026-09-01', notes: { info: 'a' } }),
			lesson({ periodId: 2, lessonId: 100, date: '2026-09-08', notes: { info: 'b' } }),
		];
		const log = await collectLessonLog(client(lessons, { 2: [] }), { from: '2026-09-01', to: '2026-09-30' });
		assert.deepEqual(log.entries.map((entry) => entry.date), ['2026-09-08', '2026-09-01']);
	});
});

describe('lessonLogText', () => {
	it('carries the topic, the announcement and the homework into one body', () => {
		const body = lessonLogText({
			periodId: 1, lessonId: 100, date: '2026-09-01', start: '08:00', end: '08:45',
			teachers: ['Meier'], topic: 'Erörterung', notes: { info: 'LK am 20.09.' },
			homework: [{ text: 'S. 42', due: '2026-09-08' }],
		});
		assert.match(body, /Erörterung/);
		assert.match(body, /LK am 20\.09\./);
		assert.match(body, /S\. 42/);
	});
});

describe('hasContent', () => {
	it('is false for a lesson that recorded nothing', () => {
		assert.equal(
			hasContent({ periodId: 1, lessonId: 1, date: '2026-09-01', start: '08:00', end: '08:45', teachers: [], notes: {}, homework: [] }),
			false,
		);
	});
});