#!/usr/bin/env node
/**
 * patch-x07-seq-step-calc.js
 * 修复 agent-isolation-gate.js B2 规则: seq 三参数形式步长被忽略
 * seq FIRST STEP LAST → n = floor((LAST - FIRST) / STEP) + 1
 *
 * 幂等: SENTINEL 标记
 */
'use strict';
const fs = require('fs');
const path = require('path');

const SENTINEL = '[PATCH-X07-SEQ-STEP]';
const TARGET = path.join(__dirname, '..', '..', 'hooks', 'agent-isolation-gate.js');

if (!fs.existsSync(TARGET)) { console.log('SKIP: target not found'); process.exit(0); }

let src = fs.readFileSync(TARGET, 'utf8');
if (src.includes(SENTINEL)) { console.log('SKIP: already patched'); process.exit(0); }

// 替换 B2 seq 计算块 (行 80-86)
const oldBlock = [
  "  const seqMatch = c.match(/\\bseq\\s+(\\d+)(?:\\s+(\\d+))?(?:\\s+(\\d+))?/);",
  "  if (seqMatch) {",
  "    const a = parseInt(seqMatch[1], 10);",
  "    const b = seqMatch[2] ? parseInt(seqMatch[2], 10) : null;",
  "    const z = seqMatch[3] ? parseInt(seqMatch[3], 10) : (b !== null ? b : a);",
  "    const n = b !== null && z !== null ? Math.max(0, z - a + 1) : a;",
  "    if (n >= 6) return { rule: 'B2', detail: 'seq ' + n };",
  "  }"
].join('\n');

// seq 语义: seq LAST / seq FIRST LAST / seq FIRST STEP LAST
const newBlock = [
  "  const seqMatch = c.match(/\\bseq\\s+(\\d+)(?:\\s+(\\d+))?(?:\\s+(\\d+))?/); // " + SENTINEL,
  "  if (seqMatch) {",
  "    let n;",
  "    const g1 = parseInt(seqMatch[1], 10);",
  "    const g2 = seqMatch[2] ? parseInt(seqMatch[2], 10) : null;",
  "    const g3 = seqMatch[3] ? parseInt(seqMatch[3], 10) : null;",
  "    if (g3 !== null) {",
  "      // seq FIRST STEP LAST",
  "      const step = Math.max(1, g2);",
  "      n = Math.max(0, Math.floor((g3 - g1) / step) + 1);",
  "    } else if (g2 !== null) {",
  "      // seq FIRST LAST",
  "      n = Math.max(0, g2 - g1 + 1);",
  "    } else {",
  "      // seq LAST (从 1 到 LAST)",
  "      n = g1;",
  "    }",
  "    if (n >= 6) return { rule: 'B2', detail: 'seq ' + n };",
  "  }"
].join('\n');

if (!src.includes(oldBlock)) {
  console.error('FAIL: old block not found (already modified?)');
  process.exit(1);
}

src = src.replace(oldBlock, newBlock);

const tmp = TARGET + '.tmp.' + process.pid;
fs.writeFileSync(tmp, src, 'utf8');
fs.renameSync(tmp, TARGET);

// 冒烟验证
const patched = fs.readFileSync(TARGET, 'utf8');
if (!patched.includes(SENTINEL)) { console.error('FAIL: sentinel missing after patch'); process.exit(1); }
if (!patched.includes('Math.floor((g3 - g1) / step)')) { console.error('FAIL: step formula missing'); process.exit(1); }

console.log('OK: X07 seq step calc patched');