import fs from 'node:fs';
import path from 'node:path';

export const BRAND_SPEC_REL = '.design_library/kole-ui/brand/brand-mark.json';
export const BRAND_DATA_REL = 'site/brand-mark.generated.json';
export const BRAND_ASSET_REL = 'site/assets/kole-mark.svg';
export const BRAND_MONO_REL = 'site/assets/kole-mark-mono.svg';
export const BRAND_SCHEMA_VERSION = 3;

export function readBrandSpec(root) {
  const file = path.join(root, BRAND_SPEC_REL);
  return JSON.parse(fs.readFileSync(file, 'utf8').replace(/^\uFEFF/, ''));
}

/** 路径项归一化：允许写成字符串（简化）或对象 { d, evenodd }（负空间需要 evenodd）。 */
function normalizePaths(raw) {
  if (!Array.isArray(raw)) return [];
  return raw.map((item) => {
    if (typeof item === 'string') return { d: item, evenodd: false };
    if (item && typeof item.d === 'string') return { d: item.d, evenodd: !!item.evenodd };
    return { d: '', evenodd: false };
  });
}

export function validateBrandSpec(spec) {
  const errors = [];
  if (!spec || spec.schemaVersion !== BRAND_SCHEMA_VERSION) {
    errors.push(`schemaVersion 必须为 ${BRAND_SCHEMA_VERSION}`);
  }
  if (!spec || spec.viewBox !== '0 0 24 24') errors.push('viewBox 必须为 0 0 24 24');

  const g = spec?.geometry || {};
  const paths = normalizePaths(g.paths);
  if (!paths.length || paths.some((p) => !p.d.trim())) {
    errors.push('geometry.paths 必须包含至少一条非空路径（字符串或 { d, evenodd }）');
  }
  if (g.mode !== 'fill' && g.mode !== 'stroke') errors.push('geometry.mode 必须为 fill 或 stroke');
  if (g.mode === 'stroke') {
    if (g.strokeWidth !== 1.5) errors.push('stroke 模式的 geometry.strokeWidth 必须为 1.5');
    if (g.linecap !== 'round') errors.push('stroke 模式的 geometry.linecap 必须为 round');
    if (g.linejoin !== 'round') errors.push('stroke 模式的 geometry.linejoin 必须为 round');
  }
  if (g.opacities !== undefined) {
    if (!Array.isArray(g.opacities) || g.opacities.length !== paths.length) {
      errors.push('geometry.opacities 必须与 paths 等长');
    } else if (g.opacities.some((v) => typeof v !== 'number' || !(v > 0) || v > 1)) {
      errors.push('geometry.opacities 取值必须在 (0, 1] 区间');
    }
  }

  if (!/^#[0-9A-Fa-f]{6}$/.test(spec?.favicon?.background || '')) errors.push('favicon.background 必须为六位十六进制颜色');
  if (!/^#[0-9A-Fa-f]{6}$/.test(spec?.favicon?.foreground || '')) errors.push('favicon.foreground 必须为六位十六进制颜色');
  if (spec?.favicon?.radius !== 6) errors.push('favicon.radius 必须为 6');
  for (const [key, value] of Object.entries(spec?.sizes || {})) {
    if (!Number.isFinite(value) || value <= 0) errors.push(`sizes.${key} 必须为正数`);
  }
  return errors;
}

/** 逐路径生成 <path>：负空间路径必须带 fill-rule="evenodd"，否则挖空不会生效。 */
function pathsMarkup(spec) {
  const { mode, opacities } = spec.geometry;
  return normalizePaths(spec.geometry.paths)
    .map((p, i) => {
      const opacity = mode === 'fill' && opacities && opacities[i] != null ? ` fill-opacity="${opacities[i]}"` : '';
      const rule = p.evenodd ? ' fill-rule="evenodd"' : '';
      return `<path d="${p.d}"${rule}${opacity}/>`;
    })
    .join('');
}

/** 图形的公共外层：实心走 fill，描边走 stroke；颜色由调用方决定。 */
function groupMarkup(spec, color, { mono }) {
  const { mode } = spec.geometry;
  const strokeAttrs =
    `fill="none" stroke="${mono ? '#000000' : color}" stroke-width="${spec.geometry.strokeWidth}"` +
    ` stroke-linecap="${spec.geometry.linecap}" stroke-linejoin="${spec.geometry.linejoin}"`;
  return mode === 'stroke'
    ? `<g ${strokeAttrs}>${pathsMarkup(spec)}</g>`
    : `<g fill="${mono ? '#000000' : color}">${pathsMarkup(spec)}</g>`;
}

export function renderFaviconSvg(spec) {
  return [
    `<svg xmlns="http://www.w3.org/2000/svg" viewBox="${spec.viewBox}">`,
    `<rect width="24" height="24" rx="${spec.favicon.radius}" fill="${spec.favicon.background}"/>`,
    groupMarkup(spec, spec.favicon.foreground, { mono: false }),
    '</svg>',
  ].join('');
}

export function renderMonoSvg(spec) {
  return [
    `<svg xmlns="http://www.w3.org/2000/svg" viewBox="${spec.viewBox}">`,
    groupMarkup(spec, '#000000', { mono: true }),
    '</svg>',
  ].join('');
}

export function generatedData(spec) {
  return {
    schemaVersion: spec.schemaVersion,
    name: spec.name,
    viewBox: spec.viewBox,
    geometry: {
      mode: spec.geometry.mode,
      /* 归一化后再写出：字符串项补成 { d, evenodd } 对象，保证下游拿到的结构稳定一致。 */
      paths: normalizePaths(spec.geometry.paths),
      ...(spec.geometry.opacities ? { opacities: spec.geometry.opacities } : {}),
      ...(spec.geometry.mode === 'stroke'
        ? {
            strokeWidth: spec.geometry.strokeWidth,
            linecap: spec.geometry.linecap,
            linejoin: spec.geometry.linejoin,
          }
        : {}),
    },
    favicon: {
      background: spec.favicon.background,
      foreground: spec.favicon.foreground,
      radius: spec.favicon.radius,
    },
    sizes: spec.sizes,
    assets: {
      favicon: 'assets/kole-mark.svg',
      mono: 'assets/kole-mark-mono.svg',
    },
  };
}

export function atomicWrite(file, content) {
  fs.mkdirSync(path.dirname(file), { recursive: true });
  const tmp = `${file}.tmp-${process.pid}`;
  fs.writeFileSync(tmp, content, 'utf8');
  fs.renameSync(tmp, file);
}