/**
 * Build-time: 按需注入 diy componentPlaceholder 占位
 *
 * 设计原则: 局部文本替换, 不破坏 pages.json 原有结构
 * ============================================================
 * - 不调用 JSON.parse / JSON.stringify (它们会丢失注释和预处理指令)
 * - 不剥离 // 注释
 * - 不剥离 // #ifdef / // #ifndef / // #endif 等 uni-app 预处理指令
 * - 只对每个 page 的 "style": { ... } 块做局部修改
 * - 块外的所有内容 (注释, 预处理, 缩进, 换行) 保持原样
 *
 * 工作流 (按需注入, 避免 vendor.js 膨胀):
 * 1. 扫描 components-diy/ 目录, 收集所有 diy-*.vue 组件名 (单一数据源: 文件系统)
 * 2. 逐行扫描 pages.json, 跟踪每个 page 的完整路径:
 *    - 顶层 pages[] 里的 page: 路径 = path (如 "pages/index/index")
 *    - subPackages[] 里的 page: 路径 = root + "/" + path (如 "pages_goods/category")
 * 3. 对每个 "style": { ... } 块:
 *    a) 读取对应 .vue 文件, 检查是否包含 <diy- 引用
 *    b) **只有真正用 diy 组件的 page** 才注入/保留 componentPlaceholder
 *    c) 不用的 page: 若已有 placeholder 则移除 (含 _diy_placeholder 标记)
 *    d) 用的 page:
 *       - 已有 componentPlaceholder → 跳过
 *       - 有 _diy_placeholder 标记 → 展开为完整块
 *       - 都没有 → 注入 _diy_placeholder 标记 (带逗号处理)
 * 4. 仅在文件有变化时写回
 *
 * 为什么按需注入: 给 113 个 page 全注入 54 项 placeholder, uni-app 会把所有 54 个
 * diy 组件名打进 vendor.js, 每个出现 226 次, 让 vendor.js 膨胀 ~270KB.
 * 只对真正用 <diy-*> 的 24 个 page 注入, vendor.js 维持 ~570KB, 主包减少 ~265KB.
 *
 * 调用时机: vue.config.js 顶部 (module.exports 之前) require 此文件自动执行.
 */
const path = require('path');
const fs = require('fs');

const PROJECT_ROOT = path.join(__dirname, '..');
const PAGES_JSON = path.join(PROJECT_ROOT, 'pages.json');
const DIY_DIR = path.join(PROJECT_ROOT, 'components-diy');

/**
 * 扫描 components-diy/ 目录, 收集所有 diy-* 组件名.
 * - 只匹配顶层 diy-*.vue 文件 (uni-app easycom 单文件组件)
 * - 排除子目录 (css/ js/ placeholder/) 和其它文件 (minx.js 等)
 * - 单一数据源: 文件系统, 无需手维护清单
 */
function collectDiyComponents() {
	if (!fs.existsSync(DIY_DIR)) {
		console.warn(`[InjectPlaceholder] ⚠️  ${DIY_DIR} 不存在, diy 组件清单为空`);
		return [];
	}
	const entries = fs.readdirSync(DIY_DIR, { withFileTypes: true });
	const names = [];
	for (const e of entries) {
		if (e.isFile() && e.name.startsWith('diy-') && e.name.endsWith('.vue')) {
			names.push(e.name.slice(0, -'.vue'.length));
		}
	}
	names.sort();
	return names;
}

const DIY_LIST = collectDiyComponents();

/**
 * 字符串感知的花括号计数.
 * 跳过 // 行注释和 "" 字符串内的花括号.
 * 返回该行净增的花括号深度.
 */
function netBraces(line) {
	let d = 0;
	let inStr = false;
	let esc = false;
	let i = 0;
	while (i < line.length) {
		const c = line[i];
		if (inStr) {
			if (esc) esc = false;
			else if (c === '\\') esc = true;
			else if (c === '"') inStr = false;
		} else {
			if (c === '/' && line[i + 1] === '/') break;
			if (c === '"') inStr = true;
			else if (c === '{') d++;
			else if (c === '}') d--;
		}
		i++;
	}
	return d;
}

/**
 * 在 body 中找最后一个 "有意义的" 行 (非空, 非纯注释).
 */
function lastMeaningfulIdx(bodyLines) {
	for (let j = bodyLines.length - 1; j >= 0; j--) {
		if (!/^\s*(\/\/.*)?$/.test(bodyLines[j])) return j;
	}
	return -1;
}

/**
 * 把 import specifier 解析为相对项目根的 .vue 路径(不带扩展名).
 * 仅处理 ./ ../ @/ 开头的本地路径; node_modules 等外部模块直接返回 null.
 */
function resolveVueImport(fromRel, spec) {
	let abs;
	if (spec.startsWith('@/')) {
		abs = path.join(PROJECT_ROOT, spec.slice(2));
	} else if (spec.startsWith('./') || spec.startsWith('../')) {
		abs = path.resolve(path.dirname(path.join(PROJECT_ROOT, fromRel + '.vue')), spec);
	} else {
		return null;
	}
	let rel = path.relative(PROJECT_ROOT, abs).replace(/\\/g, '/');
	if (rel.startsWith('..')) return null;
	if (!rel.endsWith('.vue')) return null;
	return rel.slice(0, -'.vue'.length);
}

/**
 * 缓存: 相对路径 → 是否(直接或传递)使用了 <diy-*>.
 */
const _usesDiyCache = new Map();
const _importRe = /import\s+[^'"`;\n]*['"]([^'"`]+\.vue)['"]/g;

/**
 * 检查一个 .vue 文件是否(传递)使用了 <diy-*> 组件.
 * 不仅看模板里是否含 <diy-, 还会沿 import 链继续追踪子组件.
 * 例如 pages_goods/detail.vue → _components/goods-detail-view/goods-detail-view.vue → <diy-icon>
 */
function fileUsesDiy(relVuePath) {
	if (!relVuePath) return false;
	if (_usesDiyCache.has(relVuePath)) return _usesDiyCache.get(relVuePath);
	// 暂存 false 以打破循环引用
	_usesDiyCache.set(relVuePath, false);
	const abs = path.join(PROJECT_ROOT, relVuePath + '.vue');
	let content;
	try {
		content = fs.readFileSync(abs, 'utf-8');
	} catch (e) {
		return false;
	}
	if (/<diy-/.test(content)) {
		_usesDiyCache.set(relVuePath, true);
		return true;
	}
	_importRe.lastIndex = 0;
	let m;
	while ((m = _importRe.exec(content)) !== null) {
		const target = resolveVueImport(relVuePath, m[1]);
		if (target && fileUsesDiy(target)) {
			_usesDiyCache.set(relVuePath, true);
			return true;
		}
	}
	return false;
}

/**
 * 检查 page 的 .vue 文件(或其传递子组件)是否引用了 <diy-*> 组件.
 * fullPagePath 是 pages.json 中拼接的页面路径, 如 "pages_goods/detail".
 */
function pageUsesDiy(fullPagePath) {
	return fileUsesDiy(fullPagePath);
}

/**
 * 从 body 中移除 componentPlaceholder 块和 _diy_placeholder 标记.
 * 用于: page 之前注入了 placeholder, 但重构后不再使用 diy 组件.
 * 自动修正尾逗号, 保证移除后 JSON 仍合法.
 */
function stripPlaceholderFromBody(bodyLines) {
	let startIdx = -1, endIdx = -1, braceDepth = 0;
	for (let i = 0; i < bodyLines.length; i++) {
		const line = bodyLines[i];
		if (startIdx === -1) {
			const m = line.match(/^\s*"componentPlaceholder"\s*:\s*\{/);
			if (m) {
				startIdx = i;
				const idx = line.indexOf('{', m.index);
				for (let j = idx; j < line.length; j++) {
					const c = line[j];
					if (c === '{') braceDepth++;
					else if (c === '}') braceDepth--;
				}
				if (braceDepth === 0) endIdx = i;
			}
		} else {
			for (const c of line) {
				if (c === '{') braceDepth++;
				else if (c === '}') braceDepth--;
			}
			if (braceDepth === 0) { endIdx = i; break; }
		}
	}
	const toRemove = new Set();
	if (startIdx >= 0 && endIdx >= 0) {
		for (let i = startIdx; i <= endIdx; i++) toRemove.add(i);
	}
	for (let i = 0; i < bodyLines.length; i++) {
		if (/^\s*"_diy_placeholder"\s*:\s*true/.test(bodyLines[i])) toRemove.add(i);
	}
	if (toRemove.size === 0) return bodyLines;

	const newBody = [];
	for (let i = 0; i < bodyLines.length; i++) {
		if (toRemove.has(i)) continue;
		newBody.push(bodyLines[i]);
	}
	// 修正: 移除后, 新的最后有意义行不应有尾逗号
	const lastIdx = lastMeaningfulIdx(newBody);
	if (lastIdx >= 0) {
		const line = newBody[lastIdx];
		const commentMatch = line.match(/(\/\/.*)$/);
		const comment = commentMatch ? commentMatch[1] : '';
		const valuePart = line.substring(0, line.length - comment.length);
		if (valuePart.trimEnd().endsWith(',')) {
			newBody[lastIdx] = valuePart.trimEnd().replace(/,\s*$/, '') + comment;
		}
	}
	return newBody;
}

/**
 * 处理单个 style 块.
 * needsPlaceholder=true: 注入/展开/保留 componentPlaceholder
 * needsPlaceholder=false: 若已有 placeholder 则移除
 * 返回 { lines, action } action: 'expand' | 'inject-marker' | 'remove' | 'skip' | 'no-change'
 */
function processStyleBlock(openLine, bodyLines, closeLine, needsPlaceholder) {
	const styleIndent = (openLine.match(/^(\s*)/) || ['', ''])[1];
	const innerIndent = styleIndent + '\t';

	// 不需要 placeholder: 移除已有
	if (!needsPlaceholder) {
		const newBody = stripPlaceholderFromBody(bodyLines);
		if (newBody.length === bodyLines.length) {
			return { lines: [openLine, ...bodyLines, closeLine], action: 'no-change' };
		}
		return { lines: [openLine, ...newBody, closeLine], action: 'remove' };
	}

	// 需要 placeholder: 已存在 → 跳过
	if (bodyLines.some(l => /^\s*"componentPlaceholder"\s*:/.test(l))) {
		return { lines: [openLine, ...bodyLines, closeLine], action: 'skip' };
	}

	// 找 _diy_placeholder 标记, 展开
	const markerIdx = bodyLines.findIndex(l => /^\s*"_diy_placeholder"\s*:\s*true/.test(l));
	if (markerIdx >= 0) {
		const tailCommaMatch = bodyLines[markerIdx].match(/^\s*"_diy_placeholder"\s*:\s*true\s*(,?)/);
		const hasTailComma = tailCommaMatch && tailCommaMatch[1] === ',';
		const newBody = [];
		for (let j = 0; j < bodyLines.length; j++) {
			if (j === markerIdx) {
				newBody.push(`${innerIndent}"componentPlaceholder": {`);
				// JSON 不允许尾逗号, 最后一个 diy 条目不能加 ","
				for (let i = 0; i < DIY_LIST.length; i++) {
					const name = DIY_LIST[i];
					const isLast = i === DIY_LIST.length - 1;
					newBody.push(`${innerIndent}\t"${name}": "view"${isLast ? '' : ','}`);
				}
				newBody.push(`${innerIndent}}` + (hasTailComma ? ',' : ''));
			} else {
				newBody.push(bodyLines[j]);
			}
		}
		return { lines: [openLine, ...newBody, closeLine], action: 'expand' };
	}

	// 注入标记
	const newBody = bodyLines.slice();
	const lastIdx = lastMeaningfulIdx(newBody);
	if (lastIdx === -1) {
		newBody.push(`${innerIndent}"_diy_placeholder": true`);
	} else {
		const lastLine = newBody[lastIdx];
		const commentMatch = lastLine.match(/(\/\/.*)$/);
		const comment = commentMatch ? commentMatch[1] : '';
		const valuePart = lastLine.substring(0, lastLine.length - comment.length);
		if (!valuePart.trimEnd().endsWith(',')) {
			newBody[lastIdx] = valuePart.trimEnd() + ',' + (comment ? ' ' + comment.trimStart() : '');
		}
		newBody.push(`${innerIndent}"_diy_placeholder": true`);
	}
	return { lines: [openLine, ...newBody, closeLine], action: 'inject-marker' };
}

function run() {
	let raw;
	try {
		raw = fs.readFileSync(PAGES_JSON, 'utf-8');
	} catch (e) {
		console.error('[InjectPlaceholder] ❌ 读取 pages.json 失败:', e.message);
		return false;
	}

	const EOL = raw.includes('\r\n') ? '\r\n' : '\n';
	const lines = raw.split(/\r?\n/);
	const out = [];
	let i = 0;
	let currentSubRoot = null;  // 当前 subPackage 的 root, 顶层 page 时为 null
	let currentPath = null;     // 当前 page 的 path
	let expanded = 0, added = 0, removed = 0, skipped = 0, noChange = 0;

	while (i < lines.length) {
		const line = lines[i];

		// 跟踪 subPackage root
		const rootMatch = line.match(/^\s*"root"\s*:\s*"([^"]+)"/);
		if (rootMatch) {
			currentSubRoot = rootMatch[1];
			out.push(line);
			i++;
			continue;
		}

		// 跟踪 page path
		const pathMatch = line.match(/^\s*"path"\s*:\s*"([^"]+)"/);
		if (pathMatch) {
			currentPath = pathMatch[1];
			out.push(line);
			i++;
			continue;
		}

		// 处理 style 块
		const styleMatch = line.match(/^(\s*)"style"\s*:\s*\{\s*,?\s*$/);
		if (!styleMatch) {
			out.push(line);
			i++;
			continue;
		}

		const openLine = line;
		const blockStart = i;
		let depth = 1;
		i++;
		while (i < lines.length && depth > 0) {
			depth += netBraces(lines[i]);
			i++;
		}
		const blockEnd = i;

		if (depth !== 0) {
			for (let j = blockStart; j < blockEnd; j++) out.push(lines[j]);
			continue;
		}

		const blockLines = lines.slice(blockStart, blockEnd);
		const closeLine = blockLines[blockLines.length - 1];
		const bodyLines = blockLines.slice(1, -1);

		// 关键: 按需判断. 读取 .vue 文件看是否真的用了 <diy-*>.
		const fullPagePath = currentSubRoot
			? `${currentSubRoot}/${currentPath}`
			: currentPath;
		const needsPlaceholder = pageUsesDiy(fullPagePath);

		const result = processStyleBlock(openLine, bodyLines, closeLine, needsPlaceholder);
		for (const l of result.lines) out.push(l);
		if (result.action === 'expand') expanded++;
		else if (result.action === 'inject-marker') added++;
		else if (result.action === 'remove') removed++;
		else if (result.action === 'skip') skipped++;
		else if (result.action === 'no-change') noChange++;
	}

	const outText = out.join(EOL);
	if (outText !== raw) {
		try {
			fs.writeFileSync(PAGES_JSON, outText, 'utf-8');
			console.log(`[InjectPlaceholder] ✅ 展开 ${expanded}, 注入 ${added}, 移除 ${removed}, 跳过 ${skipped}, 无变化 ${noChange}, diy 组件 ${DIY_LIST.length}`);
		} catch (e) {
			console.error('[InjectPlaceholder] ❌ 写回 pages.json 失败:', e.message);
			return false;
		}
	} else {
		console.log(`[InjectPlaceholder] ✓ 无需改动, diy 组件 ${DIY_LIST.length}`);
	}
	return true;
}

run();