#!/usr/bin/env node
/**
 * Compare two Goose v1.49 memory manifests and report drift.
 */
import fs from 'node:fs/promises';
import path from 'node:path';
import { fileURLToPath } from 'node:url';

const root = path.join(path.dirname(fileURLToPath(import.meta.url)), '..');

function usage() {
  return [
    'Usage: node scripts/compare-goose-v149-memory-manifest.mjs [--baseline <path>] [--current <path>] [--json]',
    '',
    'Defaults:',
    '  baseline docs/baselines/goose-v149-memory-latest.json',
    '  current  freshly exported manifest (via child process) unless --current is set',
  ].join('\n');
}

function parseArgs(argv) {
  const args = {
    baseline: path.join(root, 'docs', 'baselines', 'goose-v149-memory-latest.json'),
    current: '',
    json: false,
    exportCurrent: true,
  };
  for (let i = 2; i < argv.length; i += 1) {
    const arg = argv[i];
    if (arg === '--baseline' && argv[i + 1]) args.baseline = path.resolve(argv[++i]);
    else if (arg === '--current' && argv[i + 1]) {
      args.current = path.resolve(argv[++i]);
      args.exportCurrent = false;
    } else if (arg === '--json') args.json = true;
    else if (arg === '--help' || arg === '-h') {
      console.log(usage());
      process.exit(0);
    } else {
      console.error(`Unknown argument: ${arg}`);
      console.error(usage());
      process.exit(2);
    }
  }
  return args;
}

async function readManifest(filePath) {
  const raw = await fs.readFile(filePath, 'utf8');
  return JSON.parse(raw);
}

function indexMemories(manifest) {
  const byId = new Map();
  for (const item of manifest.memories ?? []) {
    byId.set(item.id, item);
  }
  return byId;
}

function indexCandidates(manifest) {
  const byId = new Map();
  for (const item of manifest.candidates ?? []) {
    byId.set(item.id, item);
  }
  return byId;
}

function compareManifests(baseline, current) {
  const drift = {
    baselineDigest: baseline.summary?.digest ?? null,
    currentDigest: current.summary?.digest ?? null,
    summary: {
      userCountDelta: (current.summary?.userCount ?? 0) - (baseline.summary?.userCount ?? 0),
      memoryCountDelta: (current.summary?.memoryItemCount ?? 0) - (baseline.summary?.memoryItemCount ?? 0),
      candidateCountDelta: (current.summary?.candidateCount ?? 0) - (baseline.summary?.candidateCount ?? 0),
    },
    addedMemoryIds: [],
    removedMemoryIds: [],
    changedMemories: [],
    addedCandidateIds: [],
    removedCandidateIds: [],
    changedCandidates: [],
  };

  const base = indexMemories(baseline);
  const cur = indexMemories(current);

  for (const [id] of cur) {
    if (!base.has(id)) drift.addedMemoryIds.push(id);
  }
  for (const [id] of base) {
    if (!cur.has(id)) drift.removedMemoryIds.push(id);
  }
  for (const [id, baseItem] of base) {
    const curItem = cur.get(id);
    if (!curItem) continue;
    const fields = [
      'userId',
      'memoryHash',
      'status',
      'sourceSessionId',
      'evidenceMessageId',
    ];
    const changes = {};
    for (const field of fields) {
      if (String(baseItem[field] ?? '') !== String(curItem[field] ?? '')) {
        changes[field] = { baseline: baseItem[field] ?? null, current: curItem[field] ?? null };
      }
    }
    if (Object.keys(changes).length) {
      drift.changedMemories.push({ id, userId: baseItem.userId, changes });
    }
  }

  const baseCandidates = indexCandidates(baseline);
  const curCandidates = indexCandidates(current);
  for (const [id] of curCandidates) {
    if (!baseCandidates.has(id)) drift.addedCandidateIds.push(id);
  }
  for (const [id] of baseCandidates) {
    if (!curCandidates.has(id)) drift.removedCandidateIds.push(id);
  }
  for (const [id, baseItem] of baseCandidates) {
    const curItem = curCandidates.get(id);
    if (!curItem) continue;
    const fields = ['userId', 'status', 'sourceSessionId'];
    const changes = {};
    for (const field of fields) {
      if (String(baseItem[field] ?? '') !== String(curItem[field] ?? '')) {
        changes[field] = { baseline: baseItem[field] ?? null, current: curItem[field] ?? null };
      }
    }
    if (Object.keys(changes).length) {
      drift.changedCandidates.push({ id, userId: baseItem.userId, changes });
    }
  }

  drift.ok =
    drift.addedMemoryIds.length === 0
    && drift.removedMemoryIds.length === 0
    && drift.changedMemories.length === 0
    && drift.addedCandidateIds.length === 0
    && drift.removedCandidateIds.length === 0
    && drift.changedCandidates.length === 0
    && drift.summary.candidateCountDelta === 0;
  return drift;
}

async function exportCurrentManifest() {
  const { spawnSync } = await import('node:child_process');
  const tmpPath = path.join(root, 'docs', 'baselines', '.goose-v149-memory-current.json');
  const result = spawnSync(
    process.execPath,
    ['scripts/export-goose-v149-memory-manifest.mjs', '--output', tmpPath, '--json'],
    { cwd: root, encoding: 'utf8', env: process.env },
  );
  if (result.status !== 0) {
    throw new Error(result.stderr || result.stdout || 'export manifest failed');
  }
  return readManifest(tmpPath);
}

async function main() {
  const args = parseArgs(process.argv);
  const baseline = await readManifest(args.baseline);
  const current = args.exportCurrent ? await exportCurrentManifest() : await readManifest(args.current);
  const report = compareManifests(baseline, current);

  if (args.json) {
    console.log(JSON.stringify(report, null, 2));
  } else if (report.ok) {
    console.log('GOOSE_V149_MEMORY_DRIFT_OK: no user/memory/candidate drift');
    console.log(`  baselineDigest=${report.baselineDigest}`);
  } else {
    console.error('GOOSE_V149_MEMORY_DRIFT_FAIL:');
    console.error(
      `  memory added=${report.addedMemoryIds.length} removed=${report.removedMemoryIds.length} `
        + `changed=${report.changedMemories.length}`,
    );
    console.error(
      `  candidate added=${report.addedCandidateIds.length} removed=${report.removedCandidateIds.length} `
        + `changed=${report.changedCandidates.length} delta=${report.summary.candidateCountDelta}`,
    );
    if (report.addedMemoryIds.length) {
      console.error(`  added sample: ${report.addedMemoryIds.slice(0, 5).join(', ')}`);
    }
    if (report.removedMemoryIds.length) {
      console.error(`  removed sample: ${report.removedMemoryIds.slice(0, 5).join(', ')}`);
    }
    if (report.changedMemories.length) {
      console.error(`  changed sample: ${JSON.stringify(report.changedMemories.slice(0, 3), null, 2)}`);
    }
    process.exit(1);
  }
}

main().catch((error) => {
  console.error(`GOOSE_V149_MEMORY_DRIFT_FAIL: ${error.message}`);
  process.exit(1);
});