import {
  applyTemporalDecayToHits,
  applyTemporalDecayToScore,
  calculateTemporalDecayMultiplier,
  DEFAULT_TEMPORAL_DECAY_CONFIG,
  isEvergreenMemoryPath,
  parseMemoryDateFromPath,
} from '../temporalDecay';

const DAY_MS = 24 * 60 * 60 * 1000;

describe('calculateTemporalDecayMultiplier', () => {
  it('is 1 at age=0', () => {
    expect(
      calculateTemporalDecayMultiplier({ ageInDays: 0, halfLifeDays: 30 })
    ).toBe(1);
  });

  it('is exactly 0.5 at half-life', () => {
    expect(
      calculateTemporalDecayMultiplier({ ageInDays: 30, halfLifeDays: 30 })
    ).toBeCloseTo(0.5);
  });

  it('returns 1 for non-positive half life (no decay)', () => {
    expect(
      calculateTemporalDecayMultiplier({ ageInDays: 100, halfLifeDays: 0 })
    ).toBe(1);
    expect(
      calculateTemporalDecayMultiplier({ ageInDays: 100, halfLifeDays: -1 })
    ).toBe(1);
  });

  it('clamps negative age to 0', () => {
    expect(
      calculateTemporalDecayMultiplier({ ageInDays: -5, halfLifeDays: 30 })
    ).toBe(1);
  });
});

describe('applyTemporalDecayToScore', () => {
  it('halves score at half-life', () => {
    expect(
      applyTemporalDecayToScore({ score: 0.8, ageInDays: 30, halfLifeDays: 30 })
    ).toBeCloseTo(0.4);
  });
});

describe('parseMemoryDateFromPath', () => {
  it('parses dated memory files', () => {
    const d = parseMemoryDateFromPath('memory/2026-04-13.md');
    expect(d).not.toBeNull();
    expect(d!.getUTCFullYear()).toBe(2026);
    expect(d!.getUTCMonth()).toBe(3);
    expect(d!.getUTCDate()).toBe(13);
  });

  it('rejects invalid dates', () => {
    expect(parseMemoryDateFromPath('memory/2026-02-30.md')).toBeNull();
    expect(parseMemoryDateFromPath('memory/notes.md')).toBeNull();
    expect(parseMemoryDateFromPath('MEMORY.md')).toBeNull();
  });

  it('handles windows-style separators', () => {
    expect(parseMemoryDateFromPath('memory\\2026-04-13.md')).not.toBeNull();
  });
});

describe('isEvergreenMemoryPath', () => {
  it('treats MEMORY.md as evergreen', () => {
    expect(isEvergreenMemoryPath('MEMORY.md')).toBe(true);
    expect(isEvergreenMemoryPath('memory.md')).toBe(true);
  });

  it('treats dated files as non-evergreen', () => {
    expect(isEvergreenMemoryPath('memory/2026-04-13.md')).toBe(false);
  });

  it('treats topic files as evergreen', () => {
    expect(isEvergreenMemoryPath('memory/topics.md')).toBe(true);
    expect(isEvergreenMemoryPath('memory/architecture.md')).toBe(true);
  });

  it('treats non-memory paths as non-evergreen', () => {
    expect(isEvergreenMemoryPath('notes.md')).toBe(false);
  });
});

describe('applyTemporalDecayToHits', () => {
  const nowMs = Date.UTC(2026, 3, 13); // 2026-04-13

  it('is a no-op when disabled', () => {
    const hits = [
      { path: 'memory/2026-03-14.md', score: 0.9, createdAt: new Date(nowMs) },
    ];
    expect(applyTemporalDecayToHits(hits, { enabled: false }, nowMs)).toEqual(
      hits
    );
  });

  it('decays dated files by date in path', () => {
    const hits = [
      { path: 'memory/2026-03-14.md', score: 1.0, createdAt: new Date(nowMs) }, // 30 days old
    ];
    const out = applyTemporalDecayToHits(
      hits,
      { enabled: true, halfLifeDays: 30 },
      nowMs
    );
    expect(out[0].score).toBeCloseTo(0.5, 2);
  });

  it('does NOT decay evergreen files', () => {
    const hits = [
      {
        path: 'memory/architecture.md',
        score: 0.9,
        createdAt: new Date(nowMs - 100 * DAY_MS),
      },
    ];
    const out = applyTemporalDecayToHits(
      hits,
      { enabled: true, halfLifeDays: 30 },
      nowMs
    );
    expect(out[0].score).toBe(0.9);
  });

  it('falls back to createdAt for non-dated non-evergreen paths', () => {
    const hits = [
      {
        path: 'notes.md',
        score: 1.0,
        createdAt: new Date(nowMs - 30 * DAY_MS),
      },
    ];
    const out = applyTemporalDecayToHits(
      hits,
      { enabled: true, halfLifeDays: 30 },
      nowMs
    );
    expect(out[0].score).toBeCloseTo(0.5, 2);
  });

  it('default config is disabled with 30 day half-life', () => {
    expect(DEFAULT_TEMPORAL_DECAY_CONFIG).toEqual({
      enabled: false,
      halfLifeDays: 30,
    });
  });
});