#!/usr/bin/env node
/**
 * gen_flutter_tokens.mjs — CSS token → Dart codegen
 *
 * 唯一真相源：design/prototype/tokens.css
 * 输出：    client/lib/pangolin_tokens.gen.dart
 *
 * 生成内容（纯数据层，无 Flutter 实现逻辑）：
 *   PangolinColors   — 原色阶 hex const
 *   PangolinSpacing  — 间距 double const
 *   PangolinRadius   — 圆角 double + Radius const
 *   PangolinMotion   — 时长 Duration + Cubic const
 *   PangolinShadow   — BoxShadow List（引用 PangolinColors._tint）
 *
 * 使用：
 *   node design/codegen/gen_flutter_tokens.mjs
 */
import { readFileSync, writeFileSync, existsSync } from 'node:fs';
import { fileURLToPath } from 'node:url';
import { dirname, resolve } from 'node:path';

const __dirname = dirname(fileURLToPath(import.meta.url));
const SRC = resolve(__dirname, '../prototype/tokens.css');
const OUT = resolve(__dirname, '../../client/lib/pangolin_tokens.gen.dart');

if (!existsSync(SRC)) {
  console.error('[gen_flutter_tokens] 找不到源文件:', SRC);
  process.exit(1);
}

const css = readFileSync(SRC, 'utf8');

// ── 工具函数 ───────────────────────────────────────────────────────────

/** 从 :root { ... } 块提取 CSS 自定义属性 Map<string, string> */
function extractRootVars(css) {
  const rootMatch = css.match(/:root\s*\{([^}]+)\}/s);
  if (!rootMatch) throw new Error('找不到 :root 块');
  const vars = {};
  for (const line of rootMatch[1].split('\n')) {
    const m = line.match(/--([a-zA-Z0-9-]+)\s*:\s*(.+?)\s*;/);
    if (m) vars[m[1]] = m[2].trim();
  }
  return vars;
}

/** #RRGGBB → 0xFFRRGGBB（Dart Color hex） */
function hexToDart(hex) {
  const h = hex.replace('#', '');
  if (h.length !== 6) throw new Error(`不支持的 hex: ${hex}`);
  return `0xFF${h.toUpperCase()}`;
}

/** rgba(r, g, b, a) → 0xAARRGGBB */
function rgbaToDart(rgba) {
  const m = rgba.match(/rgba?\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*(?:,\s*([\d.]+))?\s*\)/);
  if (!m) throw new Error(`不支持的 rgba: ${rgba}`);
  const r = parseInt(m[1]).toString(16).padStart(2, '0').toUpperCase();
  const g = parseInt(m[2]).toString(16).padStart(2, '0').toUpperCase();
  const b = parseInt(m[3]).toString(16).padStart(2, '0').toUpperCase();
  const alpha = m[4] !== undefined ? Math.round(parseFloat(m[4]) * 255) : 255;
  const a = alpha.toString(16).padStart(2, '0').toUpperCase();
  return `0x${a}${r}${g}${b}`;
}

/** rem → px double（root 16px） */
function remToPx(val) {
  if (val === '0') return 0;
  const m = val.match(/([\d.]+)rem/);
  if (!m) throw new Error(`不支持的 rem: ${val}`);
  return parseFloat((parseFloat(m[1]) * 16).toFixed(1));
}

/** px 字符串 → double */
function pxToDouble(val) {
  if (val === '0') return 0;
  const m = val.match(/([\d.]+)px/);
  if (!m) throw new Error(`不支持的 px: ${val}`);
  return parseFloat(m[1]);
}

/** ms 字符串 → int */
function msToInt(val) {
  const m = val.match(/(\d+)ms/);
  if (!m) throw new Error(`不支持的 ms: ${val}`);
  return parseInt(m[1]);
}

/** cubic-bezier(a,b,c,d) → [a,b,c,d] */
function parseCubic(val) {
  const m = val.match(/cubic-bezier\(\s*([\d.]+)\s*,\s*([\d.]+)\s*,\s*([\d.]+)\s*,\s*([\d.]+)\s*\)/);
  if (!m) throw new Error(`不支持的 cubic-bezier: ${val}`);
  return [m[1], m[2], m[3], m[4]];
}

/** 解析 shadow 值：`0 1px 2px rgba(45, 30, 20, 0.06)` */
function parseShadow(val) {
  // format: 0 <offsetY>px <blur>px rgba(r,g,b,<opacity>)
  const m = val.match(/0\s+([\d.]+)px\s+([\d.]+)px\s+rgba\(\d+,\s*\d+,\s*\d+,\s*([\d.]+)\)/);
  if (!m) throw new Error(`不支持的 shadow: ${val}`);
  return { offsetY: parseFloat(m[1]), blur: parseFloat(m[2]), opacity: parseFloat(m[3]) };
}

// ── 解析 ──────────────────────────────────────────────────────────────

const vars = extractRootVars(css);

// 原色阶：hex 值
const colorRamps = {
  clay:  ['50','100','200','300','400','500','600','700','800','900'],
  sand:  ['50','100','200','300','400','500','600','700','800','900','950'],
  green: ['400','500','600'],
  amber: ['400','500','600'],
  red:   ['400','500','600'],
};

// CSS property name → Dart identifier
function cssPropToDartName(ramp, shade) {
  return `${ramp}${shade}`;
}

// ── 生成 Dart ──────────────────────────────────────────────────────────

const lines = [];

lines.push(`// pangolin_tokens.gen.dart`);
lines.push(`// AUTO-GENERATED — 勿手改。`);
lines.push(`// 源: design/prototype/tokens.css`);
lines.push(`// 生成器: design/codegen/gen_flutter_tokens.mjs`);
lines.push(`//`);
lines.push(`// 包含：PangolinColors · PangolinSpacing · PangolinRadius · PangolinMotion · PangolinShadow`);
lines.push(`// 由 pangolin_theme.dart 导入；业务代码通过 pangolin_theme.dart 的符号访问，无需直接 import 本文件。`);
lines.push(``);
lines.push(`import 'package:flutter/material.dart';`);
lines.push(``);

// ── PangolinColors ──────────────────────────────────────────────────
lines.push(`/// ── Primitive color ramps ───────────────────────────────────────────`);
lines.push(`/// Auto-generated from design/prototype/tokens.css :root color ramps.`);
lines.push(`class PangolinColors {`);
lines.push(`  PangolinColors._();`);
lines.push(``);

for (const [ramp, shades] of Object.entries(colorRamps)) {
  lines.push(`  // ${ramp.charAt(0).toUpperCase() + ramp.slice(1)}`);
  for (const shade of shades) {
    const cssKey = `${ramp}-${shade}`;
    const val = vars[cssKey];
    if (!val) throw new Error(`找不到 CSS 变量 --${cssKey}`);
    const dartHex = hexToDart(val.split(';')[0].trim().split(' ')[0]);
    const paddedName = cssPropToDartName(ramp, shade).padEnd(10);
    // extract trailing comment from CSS
    const commentMatch = vars[cssKey].match(/\/\*(.+?)\*\//);
    const comment = commentMatch ? ` // ${commentMatch[1].trim()}` : '';
    lines.push(`  static const ${paddedName}= Color(${dartHex});${comment}`);
  }
  lines.push(``);
}

lines.push(`  static const white = Color(0xFFFFFFFF);`);
lines.push(`}`);
lines.push(``);

// ── PangolinSpacing ──────────────────────────────────────────────────
lines.push(`/// ── Spacing (4px base) ──────────────────────────────────────────────`);
lines.push(`class PangolinSpacing {`);
lines.push(`  PangolinSpacing._();`);

const spacingKeys = ['space-0','space-1','space-2','space-3','space-4','space-5','space-6','space-8','space-10','space-12','space-16'];
const spacingNames = { 'space-0':'x0','space-1':'x1','space-2':'x2','space-3':'x3','space-4':'x4',
                       'space-5':'x5','space-6':'x6','space-8':'x8','space-10':'x10','space-12':'x12','space-16':'x16' };
const spacingParts = [];
for (const key of spacingKeys) {
  const val = vars[key];
  if (!val) throw new Error(`找不到 --${key}`);
  const px = remToPx(val.split(';')[0].trim().split(' ')[0]);
  spacingParts.push(`x${key.replace('space-','')} = ${px}`);
}
lines.push(`  static const double ${spacingParts.join(', ')};`);
lines.push(`}`);
lines.push(``);

// ── PangolinRadius ──────────────────────────────────────────────────
lines.push(`/// ── Radii ───────────────────────────────────────────────────────────`);
lines.push(`class PangolinRadius {`);
lines.push(`  PangolinRadius._();`);

const radiusMap = { 'radius-sm':'sm', 'radius-md':'md', 'radius-lg':'lg', 'radius-xl':'xl', 'radius-2xl':'xxl', 'radius-full':'full' };
const radiusParts = [];
const radiusCircParts = [];
for (const [cssKey, dartName] of Object.entries(radiusMap)) {
  const val = vars[cssKey];
  if (!val) throw new Error(`找不到 --${cssKey}`);
  const px = pxToDouble(val.split(';')[0].trim().split(' ')[0]);
  radiusParts.push(`${dartName} = ${px}`);
  if (dartName !== 'full') {
    const capName = dartName.charAt(0).toUpperCase() + dartName.slice(1);
    radiusCircParts.push(`r${capName} = Radius.circular(${dartName})`);
  }
}
lines.push(`  static const double ${radiusParts.join(', ')};`);
lines.push(`  static const rSm = Radius.circular(sm);`);
lines.push(`  static const rMd = Radius.circular(md);`);
lines.push(`  static const rLg = Radius.circular(lg);`);
lines.push(`  static const rXl = Radius.circular(xl);`);
lines.push(`  static const rXxl = Radius.circular(xxl);`);
lines.push(`}`);
lines.push(``);

// ── PangolinMotion ──────────────────────────────────────────────────
lines.push(`/// ── Motion ──────────────────────────────────────────────────────────`);
lines.push(`class PangolinMotion {`);
lines.push(`  PangolinMotion._();`);

const durFast = msToInt(vars['dur-fast']);
const durBase = msToInt(vars['dur-base']);
const durSlow = msToInt(vars['dur-slow']);
lines.push(`  static const fast = Duration(milliseconds: ${durFast});`);
lines.push(`  static const base = Duration(milliseconds: ${durBase});`);
lines.push(`  static const slow = Duration(milliseconds: ${durSlow});`);

const easeOut = parseCubic(vars['ease-out']);
const easeInOut = parseCubic(vars['ease-in-out']);
lines.push(`  static const easeOut    = Cubic(${easeOut.join(', ')});`);
lines.push(`  static const easeInOut  = Cubic(${easeInOut.join(', ')});`);
lines.push(`}`);
lines.push(``);

// ── PangolinShadow ──────────────────────────────────────────────────
lines.push(`/// ── Soft warm-tinted shadows (light mode) ─────────────────────────`);
lines.push(`class PangolinShadow {`);
lines.push(`  PangolinShadow._();`);
lines.push(`  static const _tint = Color(0xFF2D1E14); // rgba(45, 30, 20) warm shadow tint`);

for (const name of ['sm','md','lg','xl']) {
  const val = vars[`shadow-${name}`];
  if (!val) throw new Error(`找不到 --shadow-${name}`);
  const s = parseShadow(val);
  lines.push(`  static List<BoxShadow> ${name} = [BoxShadow(color: _tint.withValues(alpha: ${s.opacity}), blurRadius: ${s.blur}, offset: const Offset(0, ${s.offsetY}))];`);
}
lines.push(`}`);
lines.push(``);

// ── 写文件 ────────────────────────────────────────────────────────────

const output = lines.join('\n');
writeFileSync(OUT, output, 'utf8');
console.log(`[gen_flutter_tokens] ✅ 已生成 ${OUT} (${output.length} 字节)`);