// ==UserScript==
// @name         图片下载工具
// @namespace    https://tampermonkey.net/
// @version      1.0.2
// @description  双击图片下载或点击下载图标
// @match        *://*/*
// @grant        GM_download
// @grant        GM_getValue
// @grant        GM_setValue
// @grant        GM_registerMenuCommand
// @run-at       document-idle
// @license MIT
// @downloadURL https://update.greasyfork.icu/scripts/572743/%E5%9B%BE%E7%89%87%E4%B8%8B%E8%BD%BD%E5%B7%A5%E5%85%B7.user.js
// @updateURL https://update.greasyfork.icu/scripts/572743/%E5%9B%BE%E7%89%87%E4%B8%8B%E8%BD%BD%E5%B7%A5%E5%85%B7.meta.js
// ==/UserScript==

(function () {
	'use strict';

	const ENABLE_KEY = 'imageDownloaderEnabled';
	const MIN_WIDTH_KEY = 'imageDownloaderMinWidth';
	const MIN_HEIGHT_KEY = 'imageDownloaderMinHeight';
	const MIN_SIZE_DEFAULT = 200;
	const ICON_SIZE = 24;
	const ICON_GAP = 6;

	let isEnabled = GM_getValue(ENABLE_KEY, true);
	let minWidth = normalizeMinSizeValue(GM_getValue(MIN_WIDTH_KEY, MIN_SIZE_DEFAULT));
	let minHeight = normalizeMinSizeValue(GM_getValue(MIN_HEIGHT_KEY, MIN_SIZE_DEFAULT));
	let currentImage = null;
	let currentHost = null;
	let leaveTimer = null;

	const icon = document.createElement('button');
	icon.type = 'button';
	icon.innerHTML = '<svg viewBox="0 0 24 24" width="14" height="14" aria-hidden="true"><path fill="currentColor" d="M12 3a1 1 0 0 1 1 1v9.59l2.3-2.3a1 1 0 1 1 1.4 1.42l-4 3.98a1 1 0 0 1-1.4 0l-4-3.98a1 1 0 1 1 1.4-1.42l2.3 2.3V4a1 1 0 0 1 1-1Zm-6 15a1 1 0 0 1 1 1v1h10v-1a1 1 0 1 1 2 0v2a1 1 0 0 1-1 1H6a1 1 0 0 1-1-1v-2a1 1 0 0 1 1-1Z"/></svg>';
	icon.style.position = 'absolute';
	icon.style.width = `${ICON_SIZE}px`;
	icon.style.height = `${ICON_SIZE}px`;
	icon.style.display = 'flex';
	icon.style.alignItems = 'center';
	icon.style.justifyContent = 'center';
	icon.style.padding = '0';
	icon.style.border = '0';
	icon.style.borderRadius = '999px';
	icon.style.background = 'rgba(0, 0, 0, 0.7)';
	icon.style.color = '#fff';
	icon.style.cursor = 'pointer';
	icon.style.zIndex = '2147483647';
	icon.style.visibility = 'hidden';
	icon.style.boxShadow = '0 2px 8px rgba(0,0,0,0.35)';

	function registerMenu() {
		const label = isEnabled ? '图片下载：已开启（点击关闭）' : '图片下载：已关闭（点击开启）';
		GM_registerMenuCommand(label, () => {
			isEnabled = !isEnabled;
			GM_setValue(ENABLE_KEY, isEnabled);
			if (!isEnabled) {
				hideIcon();
			}
			location.reload();
		});
		GM_registerMenuCommand(`最小尺寸：${minWidth} x ${minHeight}（点击设置）`, () => {
			const widthInput = window.prompt('请输入最小宽度（像素）', String(minWidth));
			if (widthInput === null) {
				return;
			}
			const heightInput = window.prompt('请输入最小高度（像素）', String(minHeight));
			if (heightInput === null) {
				return;
			}
			const nextWidth = parseInt(widthInput, 10);
			const nextHeight = parseInt(heightInput, 10);
			if (!Number.isFinite(nextWidth) || !Number.isFinite(nextHeight) || nextWidth <= 0 || nextHeight <= 0) {
				window.alert('请输入大于 0 的整数宽高');
				return;
			}
			minWidth = nextWidth;
			minHeight = nextHeight;
			GM_setValue(MIN_WIDTH_KEY, minWidth);
			GM_setValue(MIN_HEIGHT_KEY, minHeight);
			hideIcon();
			location.reload();
		});
	}

	function normalizeMinSizeValue(value) {
		const parsed = parseInt(String(value), 10);
		if (!Number.isFinite(parsed) || parsed <= 0) {
			return MIN_SIZE_DEFAULT;
		}
		return parsed;
	}

	function getImageUrl(img) {
		if (!img) {
			return '';
		}
		if (img.currentSrc) {
			return img.currentSrc;
		}
		return img.src || '';
	}

	function getFilenameFromUrl(url) {
		try {
			const parsed = new URL(url, location.href);
			const raw = parsed.pathname.split('/').pop() || '';
			const safe = raw.replace(/[\\/:*?"<>|]/g, '_');
			if (safe) {
				return safe;
			}
		} catch (error) {
			const fallback = String(url || '').split('/').pop()?.split('?')[0] || '';
			const safe = fallback.replace(/[\\/:*?"<>|]/g, '_');
			if (safe) {
				return safe;
			}
		}
		return `image_${Date.now()}.jpg`;
	}

	function downloadImage(url) {
		if (!isEnabled || !url) {
			return;
		}
		if (url.startsWith('data:')) {
			return;
		}
		GM_download({
			url,
			name: getFilenameFromUrl(url),
			saveAs: false
		});
	}

	function ensureHostPosition(host) {
		const computed = window.getComputedStyle(host).position;
		if (computed === 'static') {
			host.dataset.tmImageDownloaderRelative = '1';
			host.style.position = 'relative';
		}
	}

	function isImageSizeValid(img) {
		if (!(img instanceof HTMLImageElement)) {
			return false;
		}
		const width = img.naturalWidth || img.clientWidth || img.width || 0;
		const height = img.naturalHeight || img.clientHeight || img.height || 0;
		return width >= minWidth && height >= minHeight;
	}

	function attachIconToImage(img) {
		if (!img || !isEnabled) {
			return;
		}
		if (!isImageSizeValid(img)) {
			hideIcon();
			return;
		}
		const host = img.parentElement;
		if (!host) {
			return;
		}
		ensureHostPosition(host);
		currentImage = img;
		currentHost = host;
		if (!host.contains(icon)) {
			host.appendChild(icon);
		}
		const left = img.offsetLeft + img.clientWidth - ICON_SIZE - ICON_GAP;
		const top = img.offsetTop + ICON_GAP;
		icon.style.left = `${Math.max(ICON_GAP, left)}px`;
		icon.style.top = `${Math.max(ICON_GAP, top)}px`;
		icon.style.visibility = 'visible';
	}

	function hideIcon() {
		icon.style.visibility = 'hidden';
		if (icon.parentElement) {
			icon.parentElement.removeChild(icon);
		}
		currentImage = null;
		currentHost = null;
	}

	function bindImage(img) {
		if (!img || img.dataset.tmImageDownloaderBound === '1') {
			return;
		}
		img.dataset.tmImageDownloaderBound = '1';
		img.addEventListener('mouseenter', () => {
			clearTimeout(leaveTimer);
			attachIconToImage(img);
		});
		img.addEventListener('mouseleave', () => {
			leaveTimer = window.setTimeout(() => {
				if (!icon.matches(':hover')) {
					hideIcon();
				}
			}, 100);
		});
	}

	function bindAllImages(root) {
		const scope = root && root.querySelectorAll ? root : document;
		const images = scope.querySelectorAll('img');
		images.forEach(bindImage);
	}

	function observeImages() {
		const observer = new MutationObserver((mutations) => {
			for (const mutation of mutations) {
				mutation.addedNodes.forEach((node) => {
					if (!(node instanceof Element)) {
						return;
					}
					if (node.tagName && node.tagName.toLowerCase() === 'img') {
						bindImage(node);
						return;
					}
					bindAllImages(node);
				});
			}
		});
		observer.observe(document.documentElement, { childList: true, subtree: true });
	}

	icon.addEventListener('mouseenter', () => {
		clearTimeout(leaveTimer);
	});

	icon.addEventListener('mouseleave', () => {
		leaveTimer = window.setTimeout(() => {
			hideIcon();
		}, 100);
	});

	icon.addEventListener('click', (event) => {
		event.preventDefault();
		event.stopPropagation();
		const url = getImageUrl(currentImage);
		downloadImage(url);
	});

	document.addEventListener('dblclick', (event) => {
		if (!isEnabled) {
			return;
		}
		const target = event.target;
		if (!(target instanceof HTMLImageElement)) {
			return;
		}
		if (!isImageSizeValid(target)) {
			return;
		}
		const url = getImageUrl(target);
		downloadImage(url);
	}, true);

	registerMenu();
	document.documentElement.appendChild(icon);
	bindAllImages(document);
	observeImages();
})();