const fs = require('fs');
const path = require('path');
const zlib = require('zlib');
const utils = require('./../js/spine-utils.js');
const render = require('./../js/spine-render.js');

/** 简易日志（写入插件目录 thumbnails.log，便于诊断 Eagle 中的间歇失败） */
function log(msg) {
	try {
		const logPath = path.join(__dirname, '..', 'thumbnails.log');
		fs.appendFileSync(logPath, '[' + new Date().toISOString() + '] ' + msg + '\n');
	} catch (e) { /* ignore */ }
}

const sleep = (ms) => new Promise((r) => setTimeout(r, ms));

/** 插件代码版本：每次改动递增，用于确认 Eagle 是否加载到最新代码 */
const VERSION = 'v4';

/** 发现配套资源；带重试，以应对 Eagle 导入时“多文件分批写入库”的时序问题。
 *  同伴文件（骨骼/图集）可能在 Atlas 的缩略图生成后才落盘，故需等待。
 *  一旦发现即立即返回（不会傻等满窗口），窗口仅作为最坏情况的上限。
 *  采用 10 次 × 150ms ≈ 1.5 秒；间隔更密、最快感知同伴落盘。 */
async function discoverWithRetry(src, retries = 10, delay = 150) {
	let assets = null;
	for (let i = 0; i < retries; i++) {
		assets = utils.discoverAssets(src);
		if (assets.skeletonPath && assets.atlasPath) return assets;
		await sleep(delay);
	}
	return assets;
}

/** 渲染缩略图；失败时重试一次（应对偶发渲染错误） */
async function renderWithRetry(opts) {
	try {
		return await render.renderThumbnail(opts);
	} catch (e) {
		log('renderThumbnail 首次失败: ' + (e && e.message) + '，重试...');
		await sleep(150);
		return await render.renderThumbnail(opts);
	}
}

/**
 * Eagle 格式扩展缩略图处理函数。
 * 参数：{ src, dest, item }
 *  - src  : 原始文件路径（skel/skel.bytes/json/atlas/atlas.txt）
 *  - dest : 需要生成的缩略图 PNG 路径
 *  - item : 当前 item 对象（可更新宽高）
 */
module.exports = async ({ src, dest, item }) => {
	try {
		// 记录 Eagle 传入的关键信息，便于诊断 src/item 的实际形态
		log('HIT ' + VERSION + ' src=' + src + ' (isTexture=' + utils.isTextureFile(src) + ')');
		try {
			log('  item keys=' + Object.keys(item || {}).join(',') + ' | name=' + (item && item.name) + ' | id=' + (item && item.id) + ' | ext=' + (item && item.ext) + ' | isDeleted=' + (item && item.isDeleted));
		} catch (e) { /* ignore */ }

		// —— 守护：若 src 文件在库中不存在（可能是回收站 isDeleted 残留 / 临时 id），
		// 且 item 标记为已删除，则跳过，避免生成破碎/占位缩略图，交由 Eagle 自身处理。
		if (item && item.isDeleted) {
			log('  skip: item.isDeleted=true');
			return resolve(item);
		}

		// —— 防御：若 src 是图片（png/jpg/jpeg/webp），不生成占位图，
		// 而是把原始图片复制/转换为缩略图，交由系统展示真实内容。
		const srcExt = utils.extOf(path.basename(src));
		if (utils.isTextureFile(src) || srcExt === '.png' || srcExt === '.jpg' || srcExt === '.jpeg' || srcExt === '.webp') {
			await copyImageAsThumb(src, dest);
			try { const s = imageSizeOf(dest); item.width = s.width || item.width; item.height = s.height || item.height; } catch (e) {}
			return resolve(item);
		}

		const assets = await discoverWithRetry(src);

		// 找不到配套 Spine 资源
		if (!assets.skeletonPath || !assets.atlasPath) {
			log('未找到配套资源: ' + src + ' (skeleton=' + !!assets.skeletonPath + ', atlas=' + !!assets.atlasPath + ')');
			await writePlaceholder(dest, path.basename(src, utils.extOf(path.basename(src)) || ''));
			item.width = 400; item.height = 400;
			return resolve(item);
		}

		const version = utils.detectVersion(assets.skeletonPath);
		const runtimeDir = utils.chooseRuntimeDir(version, assets.isBinary);

		if (!runtimeDir) {
			await writePlaceholder(dest, path.basename(assets.skeletonPath, path.extname(assets.skeletonPath)));
			item.width = 400; item.height = 400;
			return resolve(item);
		}

		// 渲染首帧到 PNG
		const png = await renderWithRetry({
			skeletonPath: assets.skeletonPath,
			atlasPath: assets.atlasPath,
			texturePaths: assets.texturePaths,
			version,
			runtimeDir,
			size: 400,
		});

		fs.writeFileSync(dest, png);

		try {
			const size = imageSizeOf(dest);
			item.width = size.width || 400;
			item.height = size.height || 400;
		} catch (e) { /* ignore */ }

		return Promise.resolve(item);
	} catch (err) {
		// 兜底：总是生成一张有效 PNG，绝不 reject，避免 Eagle 显示默认图标
		log('缩略图处理异常: ' + (err && err.message) + '\n' + ((err && err.stack) || ''));
		try {
			await writePlaceholder(dest, 'Spine');
			item.width = 400;
			item.height = 400;
			return resolve(item);
		} catch (e2) {
			// 最后兜底：写入一张最小 1x1 PNG
			try { fs.writeFileSync(dest, Buffer.from('iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mNk+M8AAAMBAQDJ/pLvAAAAAElFTkSuQmCC', 'base64')); } catch (e3) {}
			item.width = 400; item.height = 400;
			return resolve(item);
		}
	}
};

function resolve(item) {
	return item;
}

/** 将任意图片作为缩略图复制/转换为 PNG（PNG 直接拷贝，JPG/WebP 用 @napi-rs/canvas 转换） */
async function copyImageAsThumb(src, dest) {
	const ext = path.extname(src).toLowerCase();
	if (ext === '.png') {
		fs.copyFileSync(src, dest);
		return;
	}
	if (render.canvasLib) {
		try {
			const img = await render.canvasLib.loadImage(src);
			const w = img.width, h = img.height;
			const canvas = render.canvasLib.createCanvas(w, h);
			const ctx = canvas.getContext('2d');
			ctx.drawImage(img, 0, 0, w, h);
			fs.writeFileSync(dest, canvas.toBuffer('image/png'));
			return;
		} catch (e) { /* fall through */ }
	}
	fs.copyFileSync(src, dest);
}

/** 读取 PNG 宽高（仅支持 PNG 头部） */
function imageSizeOf(file) {
	const buf = fs.readFileSync(file);
	if (buf.slice(0, 8).toString('hex') === '89504e470d0a1a0a') {
		return { width: buf.readUInt32BE(16), height: buf.readUInt32BE(20) };
	}
	return { width: 0, height: 0 };
}

/** 生成一个纯 JS 占位 PNG（无需外部依赖），作为兜底 */
async function writePlaceholder(dest, text) {
	const w = 400, h = 400;
	// 深色底
	const pixels = Buffer.alloc(w * h * 4);
	for (let y = 0; y < h; y++) {
		for (let x = 0; x < w; x++) {
			const i = (y * w + x) * 4;
			pixels[i] = 30; pixels[i + 1] = 30; pixels[i + 2] = 34; pixels[i + 3] = 255;
		}
	}
	// 简单的斜线纹理，让占位图不单调
	for (let i = 0; i < w + h; i += 8) {
		for (let k = 0; k < 3; k++) {
			const x = Math.min(w - 1, i - k);
			const y = Math.min(h - 1, k);
			const idx = (y * w + x) * 4;
			pixels[idx] = 60; pixels[idx + 1] = 62; pixels[idx + 2] = 68;
		}
	}
	fs.writeFileSync(dest, encodePng(w, h, pixels));
}

/** 最小 PNG 编码器（纯 JS，使用 zlib deflate） */
function encodePng(width, height, rgba) {
	const sig = Buffer.from([137, 80, 78, 71, 13, 10, 26, 10]);
	const ihdr = Buffer.alloc(13);
	ihdr.writeUInt32BE(width, 0);
	ihdr.writeUInt32BE(height, 4);
	ihdr[8] = 8; // bit depth
	ihdr[9] = 6; // color type RGBA
	ihdr[10] = 0; ihdr[11] = 0; ihdr[12] = 0;
	const ihdrChunk = chunk('IHDR', ihdr);

	const raw = Buffer.alloc((width * 4 + 1) * height);
	for (let y = 0; y < height; y++) {
		raw[y * (width * 4 + 1)] = 0; // filter type 0
		rgba.copy(raw, y * (width * 4 + 1) + 1, y * width * 4, (y + 1) * width * 4);
	}
	const idat = zlib.deflateSync(raw);
	const idatChunk = chunk('IDAT', idat);
	const iend = chunk('IEND', Buffer.alloc(0));
	return Buffer.concat([sig, ihdrChunk, idatChunk, iend]);
}

function chunk(type, data) {
	const len = Buffer.alloc(4);
	len.writeUInt32BE(data.length, 0);
	const typeBuf = Buffer.from(type, 'ascii');
	const crcBuf = Buffer.alloc(4);
	crcBuf.writeUInt32BE(crc32(Buffer.concat([typeBuf, data])), 0);
	return Buffer.concat([len, typeBuf, data, crcBuf]);
}

function crc32(buf) {
	let c, crc = 0xFFFFFFFF;
	for (let i = 0; i < buf.length; i++) {
		c = (crc ^ buf[i]) & 0xFF;
		for (let k = 0; k < 8; k++) c = c & 1 ? (0xEDB88320 ^ (c >>> 1)) : (c >>> 1);
		crc = (crc >>> 8) ^ c;
	}
	return (crc ^ 0xFFFFFFFF) >>> 0;
}