'use strict';

/**
 * RETENTION COMPLETION CONTRACT.
 *
 * The previous bug made the recorder write NOTHING. The dangerous successor is
 * a recorder that writes HALF and looks healthy: `persist()` writes in chunks
 * of 250 and stops at the first failed chunk, so chunks committed before the
 * failure are already durable. Rows exist, `captured_at` is uniform, Redis kept
 * working — and the cohort is short.
 *
 * So completeness is proven by the WRITER (attempted N, persisted N), never by
 * row presence.
 */

const retention = require('../../src/services/retentionService');
const { TERMINAL } = retention;

/** Chunk-faithful fake: records every chunk and fails the nominated one. */
function chunkClient({ failAtCall = null } = {}) {
  const calls = [];
  return {
    calls,
    client: {
      from: () => ({
        upsert: async (rows) => {
          calls.push(rows.length);
          if (failAtCall !== null && calls.length === failAtCall) {
            return { error: { message: 'PostgREST 400: chunk rejected', code: 'PGRST204' } };
          }
          return { error: null };
        },
      }),
    },
  };
}

const rowsN = (n) => Array.from({ length: n }, (_, i) => ({ snapshot_id: 's', player_key: `p${i}`, stat: 'hits', line: 0.5, side: 'over' }));

describe('CHUNKED PERSISTENCE — traced contract', () => {
  test('attempted is the input length; chunks are sequential and in array order', async () => {
    const f = chunkClient();
    const out = await retention.persist(rowsN(600), { getClient: () => f.client });
    expect(out.attempted).toBe(600);
    expect(f.calls).toEqual([250, 250, 100]);   // chunk size 250, final short chunk
    expect(out.written).toBe(600);
  });

  test('written counts COMMITTED CHUNK ROWS, not database inserts', async () => {
    // The upsert uses ignoreDuplicates, so a re-run legitimately inserts far
    // fewer rows than it writes. Comparing `written` to count(*) will disagree
    // by design — that is not a partial write, and this is why row counting
    // cannot be the completion test.
    const src = require('fs').readFileSync(require.resolve('../../src/services/retentionService'), 'utf8');
    expect(src).toMatch(/ignoreDuplicates: true/);
    expect(src).toMatch(/out\.written \+= chunk\.length/);
  });

  test('persist RETURNS an error, never throws it', async () => {
    const boom = { from: () => ({ upsert: async () => { throw new Error('socket hang up'); } }) };
    const out = await retention.persist(rowsN(10), { getClient: () => boom });
    expect(out.error).toMatch(/socket hang up/);
    expect(out.written).toBe(0);
  });
});

describe('TERMINAL STATE CLASSIFICATION', () => {
  const classify = (r) => retention.classifyPersist(r);

  test('ALL CHUNKS SUCCEED -> COMPLETE', async () => {
    const f = chunkClient();
    const out = await retention.persist(rowsN(600), { getClient: () => f.client });
    expect([out.attempted, out.written]).toEqual([600, 600]);
    expect(classify(out)).toBe(TERMINAL.COMPLETE);
    expect(retention.isRetentionFailure(classify(out))).toBe(false);
  });

  test('FIRST CHUNK FAILS -> FAILED_ZERO_WRITE', async () => {
    const f = chunkClient({ failAtCall: 1 });
    const out = await retention.persist(rowsN(600), { getClient: () => f.client });
    expect(out.attempted).toBe(600);
    expect(out.written).toBe(0);
    expect(classify(out)).toBe(TERMINAL.FAILED_ZERO_WRITE);
    expect(retention.isRetentionFailure(classify(out))).toBe(true);
    expect(f.calls).toHaveLength(1);            // stops immediately
  });

  test('MIDDLE CHUNK FAILS -> FAILED_PARTIAL, never COMPLETE', async () => {
    const f = chunkClient({ failAtCall: 2 });
    const out = await retention.persist(rowsN(600), { getClient: () => f.client });
    expect(out.attempted).toBe(600);
    expect(out.written).toBe(250);              // chunk 1 is DURABLE
    expect(out.written).toBeGreaterThan(0);
    expect(out.written).toBeLessThan(out.attempted);
    expect(classify(out)).toBe(TERMINAL.FAILED_PARTIAL);
    expect(classify(out)).not.toBe(TERMINAL.COMPLETE);
    expect(retention.isRetentionFailure(classify(out))).toBe(true);
  });

  test('FINAL CHUNK FAILS -> FAILED_PARTIAL', async () => {
    const f = chunkClient({ failAtCall: 3 });
    const out = await retention.persist(rowsN(600), { getClient: () => f.client });
    expect([out.attempted, out.written]).toEqual([600, 500]);
    expect(classify(out)).toBe(TERMINAL.FAILED_PARTIAL);
    expect(retention.isRetentionFailure(classify(out))).toBe(true);
  });

  test('SKIPPED (no database) -> SKIPPED_NO_DATABASE, not a failure', async () => {
    const out = await retention.persist(rowsN(600), { getClient: () => null });
    expect(out.skipped).toBe(true);
    expect(classify(out)).toBe(TERMINAL.SKIPPED_NO_DATABASE);
    expect(retention.isRetentionFailure(classify(out))).toBe(false);
  });

  test('EMPTY COHORT -> NOTHING_TO_PERSIST, not a failure', async () => {
    const out = await retention.persist([], { getClient: () => null });
    expect(out.attempted).toBe(0);
    expect(classify(out)).toBe(TERMINAL.NOTHING_TO_PERSIST);
    expect(retention.isRetentionFailure(classify(out))).toBe(false);
  });

  test('THE INVARIANT: any written < attempted with attempted > 0 is FAILED', () => {
    for (const [a, w] of [[600, 0], [600, 1], [600, 250], [600, 599], [1, 0]]) {
      const st = classify({ attempted: a, written: w, skipped: false, error: 'x' });
      expect(retention.isRetentionFailure(st)).toBe(true);
      expect(st).not.toBe(TERMINAL.COMPLETE);
    }
  });

  test('counts that look complete but carry an error are NEVER COMPLETE', () => {
    expect(classify({ attempted: 600, written: 600, skipped: false, error: 'late failure' }))
      .toBe(TERMINAL.FAILED_UNRESOLVED_ERROR);
  });

  test('classification refuses anything that is not the real persist result', () => {
    // It must never recompute or infer counts — a second calculation could
    // disagree with the writer, and then the status describes a cycle that
    // did not happen.
    expect(() => classify(null)).toThrow(TypeError);
    expect(() => classify({ attempted: '600', written: 600 })).toThrow(TypeError);
    expect(() => classify({ written: 600 })).toThrow(TypeError);
  });
});

describe('COMPLETION OBSERVABILITY', () => {
  beforeEach(() => retention.resetTerminal());

  test('recordTerminal reports the EXACT persist counts, not a recalculation', async () => {
    const f = chunkClient({ failAtCall: 2 });
    const out = await retention.persist(rowsN(600), { getClient: () => f.client });
    const e = retention.recordTerminal({
      sport: 'mlb', snapshotId: 'snap-1', result: out, completedAt: '2026-08-27T23:00:00Z',
    });
    expect(e.attempted).toBe(out.attempted);
    expect(e.written).toBe(out.written);
    expect(e.status).toBe(TERMINAL.FAILED_PARTIAL);
    expect(e.snapshot_id).toBe('snap-1');
    expect(e.sport).toBe('mlb');
    expect(e.completed_at).toBe('2026-08-27T23:00:00Z');
    expect(e).toHaveProperty('code_sha');
    expect(e.error_summary).toMatch(/chunk rejected/);
  });

  test('lastRetention exposes the latest terminal result per sport', async () => {
    const ok = chunkClient();
    const bad = chunkClient({ failAtCall: 1 });
    retention.recordTerminal({ sport: 'mlb', snapshotId: 'a', result: await retention.persist(rowsN(10), { getClient: () => ok.client }) });
    retention.recordTerminal({ sport: 'wnba', snapshotId: 'b', result: await retention.persist(rowsN(10), { getClient: () => bad.client }) });
    const last = retention.lastRetention();
    expect(last.mlb.status).toBe(TERMINAL.COMPLETE);
    expect(last.wnba.status).toBe(TERMINAL.FAILED_ZERO_WRITE);
    expect(Object.keys(last).sort()).toEqual(['mlb', 'wnba']);
  });

  test('the observable result carries every required field', () => {
    const e = retention.recordTerminal({
      sport: 'mlb', snapshotId: 's', result: { attempted: 5, written: 5, skipped: false, error: null },
    });
    for (const k of ['sport', 'snapshot_id', 'attempted', 'written', 'status', 'completed_at', 'code_sha', 'error_summary']) {
      expect(Object.keys(e)).toContain(k);
    }
  });

  test('it never exposes row payloads', async () => {
    const bad = { from: () => ({ upsert: async () => ({ error: { message: 'x'.repeat(5000) } }) }) };
    const out = await retention.persist(rowsN(10), { getClient: () => bad });
    const e = retention.recordTerminal({ sport: 'mlb', snapshotId: 's', result: out });
    expect(e.error_summary.length).toBeLessThanOrEqual(300);
    expect(JSON.stringify(e)).not.toMatch(/player_key/);
  });

  test('the internal status route exposes it behind existing internal auth', () => {
    const src = require('fs').readFileSync(require.resolve('../../src/routes/internal.js'), 'utf8');
    expect(src).toMatch(/last_retention: lastRetention\(\)/);
    // Read-only, and no second calculation in the route.
    expect(src).not.toMatch(/last_retention[\s\S]{0,200}attempted:/);
    expect(src).toMatch(/requireInternalAuth/);
  });
});

describe('PARTIAL FAILURE IS VISIBLE AT THE CALL SITE', () => {
  const src = require('fs').readFileSync(require.resolve('../../src/services/snapshotService.js'), 'utf8');
  const block = src.slice(src.indexOf('const terminal = retention.recordTerminal'),
    src.indexOf('const terminal = retention.recordTerminal') + 2200);

  test('the alert is driven by TERMINAL STATUS, not by a written===0 test', () => {
    expect(block).toMatch(/retention\.isRetentionFailure\(terminal\.status\)/);
    // The old condition could not see a partial as a distinct state.
    expect(src).not.toMatch(/r\.attempted > 0 && r\.written === 0/);
  });

  test('a failed cohort alert carries every required field', () => {
    for (const f of ['${terminal.status}', 'stage=model_snapshots', 'snapshot_id=${terminal.snapshot_id}',
      'code_sha=${terminal.code_sha', 'at=${terminal.completed_at}', 'error=${terminal.error_summary']) {
      expect(block).toContain(f);
    }
    expect(block).toContain('${terminal.written}/${terminal.attempted}');
    expect(block).toMatch(/priority: 'high'/);
  });

  test('a partial cohort is labelled unusable as evidence, not degraded success', () => {
    expect(block).toMatch(/INCOMPLETE and must not be used as evidence/);
    expect(block).toMatch(/product is unaffected/);   // best-effort preserved
  });

  test('the terminal result recorded is the one persist returned', () => {
    expect(block).toMatch(/result: r,/);
    expect(block).not.toMatch(/attempted:\s*rows\.length/);
  });
});

describe('ROW PRESENCE IS NEVER COMPLETION', () => {
  const fs = require('fs');
  const strip = (t) => t.replace(/\/\*[\s\S]*?\*\//g, '').replace(/(^|[^:])\/\/.*$/gm, '$1');

  test('COMPLETE is decided in exactly one place — classifyPersist', () => {
    const src = strip(fs.readFileSync(require.resolve('../../src/services/retentionService'), 'utf8'));
    // One definition in the TERMINAL map, one return in classifyPersist.
    const assigns = src.match(/TERMINAL\.COMPLETE/g) || [];
    expect(assigns.length).toBe(1);
    const body = src.slice(src.indexOf('function classifyPersist'));
    expect(body).toMatch(/TERMINAL\.COMPLETE/);
  });

  test('no consumer derives completion from row counts or timestamps', () => {
    for (const f of ['../../src/services/snapshotService', '../../src/routes/internal.js']) {
      const src = strip(fs.readFileSync(require.resolve(f), 'utf8'));
      // A completion verdict must come from the writer, never from counting
      // rows that survived, or from a uniform captured_at.
      expect(src).not.toMatch(/status\s*[:=]\s*['"]COMPLETE['"]/);
      expect(src).not.toMatch(/COMPLETE[\s\S]{0,80}(rows\.length|count\(|captured_at)/);
    }
  });

  test('the call site passes the persist result through, never a substitute', () => {
    const src = strip(fs.readFileSync(require.resolve('../../src/services/snapshotService'), 'utf8'));
    const i = src.indexOf('retention.recordTerminal');
    const block = src.slice(i, i + 400);
    expect(block).toMatch(/result: r,/);
    expect(block).not.toMatch(/status:/);          // no hand-set status
    expect(block).not.toMatch(/attempted:/);       // no recalculated counts
    expect(block).not.toMatch(/written:/);
  });
});