Support overnight blocks in schedule validation

src/lib/schedule-utils.spec.ts

@@ -1,7 +1,10 @@
 import { describe, it, expect } from 'vitest';
 import {
+	blockDuration,
+	blockSegments,
 	findOverlap,
 	formatTime,
+	isOvernight,
 	snapMinutes,
 	toHm,
 	validateBlock,
@@ -52,6 +55,49 @@ describe('snapMinutes', () => {
 	});
 });
 
+describe('isOvernight', () => {
+	it('is true when the end clock time is before the start', () => {
+		expect(isOvernight({ startMinutes: 21 * 60, endMinutes: 9 * 60 })).toBe(true);
+		expect(isOvernight({ startMinutes: 22 * 60, endMinutes: 0 })).toBe(true);
+	});
+
+	it('is false for same-day ranges and a full-day range', () => {
+		expect(isOvernight({ startMinutes: 6 * 60, endMinutes: 8 * 60 })).toBe(false);
+		expect(isOvernight({ startMinutes: 0, endMinutes: 1440 })).toBe(false);
+	});
+});
+
+describe('blockDuration', () => {
+	it('counts a same-day range directly', () => {
+		expect(blockDuration({ startMinutes: 6 * 60, endMinutes: 8 * 60 })).toBe(120);
+	});
+
+	it('counts an overnight range as wrapping to the next day', () => {
+		expect(blockDuration({ startMinutes: 21 * 60, endMinutes: 9 * 60 })).toBe(720);
+	});
+
+	it('treats an end of midnight as wrapping from the start', () => {
+		expect(blockDuration({ startMinutes: 22 * 60, endMinutes: 0 })).toBe(120);
+	});
+});
+
+describe('blockSegments', () => {
+	it('returns a single segment for a same-day range', () => {
+		expect(blockSegments({ startMinutes: 6 * 60, endMinutes: 8 * 60 })).toEqual([[6 * 60, 8 * 60]]);
+	});
+
+	it('splits an overnight range at midnight', () => {
+		expect(blockSegments({ startMinutes: 21 * 60, endMinutes: 9 * 60 })).toEqual([
+			[21 * 60, 1440],
+			[0, 9 * 60]
+		]);
+	});
+
+	it('returns no segments for a zero-length range', () => {
+		expect(blockSegments({ startMinutes: 360, endMinutes: 360 })).toEqual([]);
+	});
+});
+
 describe('findOverlap', () => {
 	it('returns null for adjacent ranges', () => {
 		expect(
@@ -63,6 +109,28 @@ describe('findOverlap', () => {
 		const other = sibling(7 * 60, 9 * 60);
 		expect(findOverlap({ startMinutes: 8 * 60, endMinutes: 10 * 60 }, [other])).toBe(other);
 	});
+
+	it('detects an overnight block overlapping an early-morning block', () => {
+		const other = sibling(8 * 60, 10 * 60);
+		expect(findOverlap({ startMinutes: 21 * 60, endMinutes: 9 * 60 }, [other])).toBe(other);
+	});
+
+	it('detects an overnight block overlapping a late-evening block', () => {
+		const other = sibling(20 * 60, 22 * 60);
+		expect(findOverlap({ startMinutes: 21 * 60, endMinutes: 9 * 60 }, [other])).toBe(other);
+	});
+
+	it('allows an overnight block and its exact complement (adjacent at both ends)', () => {
+		expect(
+			findOverlap({ startMinutes: 21 * 60, endMinutes: 9 * 60 }, [sibling(9 * 60, 21 * 60)])
+		).toBeNull();
+	});
+
+	it('allows an overnight block and a midday block it does not touch', () => {
+		expect(
+			findOverlap({ startMinutes: 21 * 60, endMinutes: 9 * 60 }, [sibling(10 * 60, 20 * 60)])
+		).toBeNull();
+	});
 });
 
 describe('validateBlock', () => {
@@ -74,17 +142,40 @@ describe('validateBlock', () => {
 		const result = validateBlock(input({ endMinutes: 6 * 60 }), []);
 		expect(result).toEqual({
 			ok: false,
-			error: "Start time must be before end time. Overnight blocks aren't supported."
+			error: "Start and end time can't be the same."
 		});
 	});
 
-	it('rejects an end time past midnight (overnight blocks disallowed)', () => {
-		const result = validateBlock(input({ startMinutes: 23 * 60, endMinutes: 25 * 60 }), []);
-		expect(result.ok).toBe(false);
+	it('rejects a time outside the 24-hour range', () => {
+		expect(validateBlock(input({ startMinutes: 23 * 60, endMinutes: 25 * 60 }), [])).toEqual({
+			ok: false,
+			error: 'Enter a valid start and end time.'
+		});
 	});
 
 	it('rejects a negative start time', () => {
-		expect(validateBlock(input({ startMinutes: -1 }), []).ok).toBe(false);
+		expect(validateBlock(input({ startMinutes: -1 }), [])).toEqual({
+			ok: false,
+			error: 'Enter a valid start and end time.'
+		});
+	});
+
+	it('accepts an overnight block', () => {
+		expect(
+			validateBlock(input({ startMinutes: 21 * 60, endMinutes: 9 * 60 }), [], {
+				isCreate: true
+			})
+		).toEqual({ ok: true });
+	});
+
+	it('rejects an overnight block that overlaps another and names it', () => {
+		const result = validateBlock(input({ startMinutes: 21 * 60, endMinutes: 9 * 60 }), [
+			sibling(8 * 60, 10 * 60)
+		]);
+		expect(result).toEqual({
+			ok: false,
+			error: 'This overlaps with your 8:00 AM–10:00 AM block.'
+		});
 	});
 
 	it('requires at least one proclamation', () => {