import { describe, expect, it } from 'vitest';
import {
  addUtcDays,
  availabilityModeForEntry,
  blocksToDailySchedule,
  blocksToMonthlySchedule,
  buildAvailabilitySnapshot,
  dateKeysAround,
  daysInMonth,
  scheduleTargetDay,
  startOfUtcDay,
  toDate,
  toIso,
} from '../src';

describe('toDate', () => {
  it('accepts a Date instance', () => {
    const original = new Date('2026-05-01T12:34:56.789Z');
    const result = toDate(original);
    expect(result.toISOString()).toBe('2026-05-01T12:34:56.789Z');
  });

  it('accepts an ISO string', () => {
    const result = toDate('2026-05-01T12:00:00.000Z');
    expect(result.toISOString()).toBe('2026-05-01T12:00:00.000Z');
  });

  it('accepts a timestamp number', () => {
    const ts = new Date('2026-05-01T00:00:00.000Z').getTime();
    const result = toDate(ts);
    expect(result.toISOString()).toBe('2026-05-01T00:00:00.000Z');
  });

  it('throws on invalid input', () => {
    expect(() => toDate('not-a-date')).toThrow('Invalid datetime: not-a-date');
    expect(() => toDate(NaN)).toThrow('Invalid datetime: NaN');
  });
});

describe('toIso', () => {
  it('converts any DateTimeInput to an ISO string', () => {
    expect(toIso(new Date('2026-05-01T12:00:00.000Z'))).toBe('2026-05-01T12:00:00.000Z');
    expect(toIso('2026-05-01T12:00:00.000Z')).toBe('2026-05-01T12:00:00.000Z');
  });
});

describe('startOfUtcDay', () => {
  it('strips time to 00:00:00 UTC', () => {
    const result = startOfUtcDay('2026-05-01T15:30:45.000Z');
    expect(result.toISOString()).toBe('2026-05-01T00:00:00.000Z');
  });

  it('works across month boundaries', () => {
    const result = startOfUtcDay('2026-03-31T23:59:59.999Z');
    expect(result.toISOString()).toBe('2026-03-31T00:00:00.000Z');
  });
});

describe('addUtcDays', () => {
  it('adds days', () => {
    const result = addUtcDays('2026-05-01T12:00:00.000Z', 5);
    expect(result.toISOString()).toBe('2026-05-06T00:00:00.000Z');
  });

  it('subtracts days', () => {
    const result = addUtcDays('2026-05-01T12:00:00.000Z', -1);
    expect(result.toISOString()).toBe('2026-04-30T00:00:00.000Z');
  });
});

describe('scheduleTargetDay', () => {
  it('returns tomorrow at UTC midnight', () => {
    const result = scheduleTargetDay('2026-05-01T10:00:00.000Z');
    expect(result.toISOString()).toBe('2026-05-02T00:00:00.000Z');
  });
});

describe('daysInMonth', () => {
  it('returns 31 for January', () => {
    expect(daysInMonth(new Date('2026-01-15T00:00:00.000Z'))).toBe(31);
  });

  it('returns 28 for February in a non-leap year', () => {
    expect(daysInMonth(new Date('2026-02-15T00:00:00.000Z'))).toBe(28);
  });

  it('returns 29 for February in a leap year', () => {
    expect(daysInMonth(new Date('2024-02-15T00:00:00.000Z'))).toBe(29);
  });

  it('returns 30 for April', () => {
    expect(daysInMonth(new Date('2026-04-15T00:00:00.000Z'))).toBe(30);
  });

  it('returns 31 for December', () => {
    expect(daysInMonth(new Date('2026-12-15T00:00:00.000Z'))).toBe(31);
  });
});

describe('blocksToDailySchedule', () => {
  it('converts schedule blocks to entries for the target day', () => {
    const persona = { id: 'space-1', displayName: 'Mina', createdAt: '2026-05-01T00:00:00.000Z', metadata: {} };
    const blocks = [
      { startTime: '00:00', endTime: '07:00', activity: 'sleep', title: 'Sleep', availabilityMode: 'offline' as const },
      { startTime: '07:00', endTime: '09:00', activity: 'morning routine', title: 'Morning routine', availabilityMode: 'online' as const },
    ];
    const entries = blocksToDailySchedule({ persona, targetDay: '2026-05-02T10:00:00.000Z', message: 'msg', blocks });

    expect(entries).toHaveLength(2);
    expect(entries[0]!.startAt).toBe('2026-05-02T00:00:00.000Z');
    expect(entries[0]!.endAt).toBe('2026-05-02T07:00:00.000Z');
    expect(entries[0]!.activity).toBe('sleep');
    expect(entries[0]!.granularity).toBe('ten-minute');
    expect(entries[0]!.metadata['availabilityMode']).toBe('offline');
    expect(entries[1]!.startAt).toBe('2026-05-02T07:00:00.000Z');
    expect(entries[1]!.endAt).toBe('2026-05-02T09:00:00.000Z');
  });

  it('uses block description when provided', () => {
    const persona = { id: 'space-1', displayName: 'Mina', createdAt: '2026-05-01T00:00:00.000Z', metadata: {} };
    const blocks = [
      { startTime: '09:00', endTime: '18:00', activity: 'work', title: 'Work', description: 'Custom desc', availabilityMode: 'do-not-disturb' as const },
    ];
    const entries = blocksToDailySchedule({ persona, targetDay: '2026-05-02T00:00:00.000Z', message: 'msg', blocks });
    expect(entries[0]!.description).toBe('Custom desc');
  });

  it('supports 24:00 as end time to reach next midnight', () => {
    const persona = { id: 'space-1', displayName: 'Mina', createdAt: '2026-05-01T00:00:00.000Z', metadata: {} };
    const blocks = [
      { startTime: '18:00', endTime: '24:00', activity: 'rest', title: 'Rest', availabilityMode: 'online' as const },
    ];
    const entries = blocksToDailySchedule({ persona, targetDay: '2026-05-02T00:00:00.000Z', message: 'msg', blocks });
    expect(entries[0]!.endAt).toBe('2026-05-03T00:00:00.000Z');
  });
});

describe('blocksToMonthlySchedule', () => {
  it('maps each block to consecutive days starting from fromDay', () => {
    const persona = { id: 'space-1', displayName: 'Mina', createdAt: '2026-05-01T00:00:00.000Z', metadata: {} };
    const blocks = [
      { startTime: '00:00', endTime: '24:00', activity: 'work', title: 'Work', availabilityMode: 'do-not-disturb' as const },
      { startTime: '00:00', endTime: '24:00', activity: 'rest', title: 'Rest', availabilityMode: 'online' as const },
    ];
    const entries = blocksToMonthlySchedule({ persona, fromDay: '2026-05-02T00:00:00.000Z', message: 'msg', blocks });

    expect(entries).toHaveLength(2);
    expect(entries[0]!.startAt).toBe('2026-05-02T00:00:00.000Z');
    expect(entries[0]!.endAt).toBe('2026-05-03T00:00:00.000Z');
    expect(entries[1]!.startAt).toBe('2026-05-03T00:00:00.000Z');
    expect(entries[1]!.endAt).toBe('2026-05-04T00:00:00.000Z');
    expect(entries[0]!.granularity).toBe('day');
  });
});

describe('availabilityModeForEntry', () => {
  it('reads availabilityMode from metadata', () => {
    expect(
      availabilityModeForEntry({
        id: '1', spaceId: 's', startAt: '', endAt: '', activity: 'anything', title: '', granularity: 'day', metadata: { availabilityMode: 'offline' },
      }),
    ).toBe('offline');
    expect(
      availabilityModeForEntry({
        id: '1', spaceId: 's', startAt: '', endAt: '', activity: 'anything', title: '', granularity: 'day', metadata: { availabilityMode: 'do-not-disturb' },
      }),
    ).toBe('do-not-disturb');
    expect(
      availabilityModeForEntry({
        id: '1', spaceId: 's', startAt: '', endAt: '', activity: 'anything', title: '', granularity: 'day', metadata: { availabilityMode: 'online' },
      }),
    ).toBe('online');
  });

  it('falls back to online when metadata is missing or invalid', () => {
    expect(
      availabilityModeForEntry({
        id: '1', spaceId: 's', startAt: '', endAt: '', activity: 'work', title: '', granularity: 'day', metadata: {},
      }),
    ).toBe('online');
    expect(
      availabilityModeForEntry({
        id: '1', spaceId: 's', startAt: '', endAt: '', activity: 'sleep', title: '', granularity: 'day', metadata: { availabilityMode: 'invalid' },
      }),
    ).toBe('online');
  });
});

describe('buildAvailabilitySnapshot', () => {
  it('filters, sorts, and merges contiguous ranges with the same mode', () => {
    const entries = [
      {
        id: 'e1', spaceId: 's', startAt: '2026-05-01T00:00:00.000Z', endAt: '2026-05-01T06:00:00.000Z',
        activity: 'sleep', title: 'Sleep', granularity: 'ten-minute' as const, metadata: { availabilityMode: 'offline' },
      },
      {
        id: 'e2', spaceId: 's', startAt: '2026-05-01T06:00:00.000Z', endAt: '2026-05-01T12:00:00.000Z',
        activity: 'work', title: 'Work', granularity: 'ten-minute' as const, metadata: { availabilityMode: 'do-not-disturb' },
      },
      {
        id: 'e3', spaceId: 's', startAt: '2026-05-01T12:00:00.000Z', endAt: '2026-05-01T18:00:00.000Z',
        activity: 'work', title: 'Work', granularity: 'ten-minute' as const, metadata: { availabilityMode: 'do-not-disturb' },
      },
      {
        id: 'e4', spaceId: 's', startAt: '2026-05-01T18:00:00.000Z', endAt: '2026-05-02T00:00:00.000Z',
        activity: 'rest', title: 'Rest', granularity: 'ten-minute' as const, metadata: { availabilityMode: 'online' },
      },
    ];

    const snapshot = buildAvailabilitySnapshot({ now: '2026-05-01T12:00:00.000Z', entries });

    expect(snapshot.windowStartAt).toBe('2026-05-01T00:00:00.000Z');
    expect(snapshot.windowEndAt).toBe('2026-05-03T00:00:00.000Z');
    expect(snapshot.ranges).toHaveLength(3);
    expect(snapshot.ranges[0]).toMatchObject({ startAt: '2026-05-01T00:00:00.000Z', endAt: '2026-05-01T06:00:00.000Z', mode: 'offline' });
    expect(snapshot.ranges[1]).toMatchObject({ startAt: '2026-05-01T06:00:00.000Z', endAt: '2026-05-01T18:00:00.000Z', mode: 'do-not-disturb' });
    expect(snapshot.ranges[2]).toMatchObject({ startAt: '2026-05-01T18:00:00.000Z', endAt: '2026-05-02T00:00:00.000Z', mode: 'online' });
  });

  it('excludes entries outside the 2-day window', () => {
    const entries = [
      {
        id: 'e1', spaceId: 's', startAt: '2026-04-30T00:00:00.000Z', endAt: '2026-04-30T23:59:59.000Z',
        activity: 'sleep', title: 'Sleep', granularity: 'day' as const, metadata: { availabilityMode: 'offline' },
      },
      {
        id: 'e2', spaceId: 's', startAt: '2026-05-01T00:00:00.000Z', endAt: '2026-05-02T00:00:00.000Z',
        activity: 'work', title: 'Work', granularity: 'day' as const, metadata: { availabilityMode: 'do-not-disturb' },
      },
    ];

    const snapshot = buildAvailabilitySnapshot({ now: '2026-05-01T12:00:00.000Z', entries });
    expect(snapshot.ranges).toHaveLength(1);
    expect(snapshot.ranges[0]!.startAt).toBe('2026-05-01T00:00:00.000Z');
  });
});

describe('dateKeysAround', () => {
  it('returns yesterday, today, and tomorrow as YYYY-MM-DD strings', () => {
    const keys = dateKeysAround('2026-05-01T12:00:00.000Z');
    expect(keys).toEqual(['2026-04-30', '2026-05-01', '2026-05-02']);
  });

  it('handles month boundaries correctly', () => {
    const keys = dateKeysAround('2026-03-01T00:00:00.000Z');
    expect(keys).toEqual(['2026-02-28', '2026-03-01', '2026-03-02']);
  });
});