const PX_PER_MM = 96 / 25.4;

export function pagePoint(x, y, rect, page, rotation) {
	const u = (x - rect.left) / rect.width;
	const v = (y - rect.top) / rect.height;
	const points = [[u, v], [v, 1 - u], [1 - u, 1 - v], [1 - v, u]];
	const point = points[rotation / 90];
	return { x: point[0] * page.width, y: point[1] * page.height };
}

export function objectTransform(box, dx, dy, corner = "") {
	if (!corner) {
		return { x: dx, y: dy, scale: 1 };
	}
	const left = corner.includes("w");
	const top = corner.includes("n");
	const x = left ? -dx : dx;
	const y = top ? -dy : dy;
	const minimum = Math.min(1, 1 / Math.min(box.width, box.height));
	const scale = Math.max(minimum, 1 + (x * box.width + y * box.height) / (box.width ** 2 + box.height ** 2));
	return { x: left ? box.width * (1 - scale) : 0, y: top ? box.height * (1 - scale) : 0, scale };
}

export function selectionBounds(items) {
	const x = Math.min(...items.map(item => item.x)), y = Math.min(...items.map(item => item.y));
	return { x, y, width: Math.max(...items.map(item => item.x + item.width)) - x,
		height: Math.max(...items.map(item => item.y + item.height)) - y };
}

function alignmentSnap(box, targets, tolerance) {
	const lines = [];
	const offset = { x: 0, y: 0 };
	for (const [axis, size, cross, span] of [["x", "width", "y", "height"], ["y", "height", "x", "width"]]) {
		let distance = Infinity, line;
		for (const target of targets) {
			for (const anchor of [0, 0.5, 1]) {
				const position = target[axis] + target[size] * anchor;
				for (const edge of [0, 0.5, 1]) {
					const delta = position - box[axis] - box[size] * edge;
					if (Math.abs(delta) > tolerance[axis] || Math.abs(delta) >= distance) continue;
					distance = Math.abs(delta);
					offset[axis] = delta;
					const from = Math.min(box[cross], target[cross]);
					const to = Math.max(box[cross] + box[span], target[cross] + target[span]);
					line = axis === "x" ? `M${position} ${from}V${to}` : `M${from} ${position}H${to}`;
				}
			}
		}
		if (line) lines.push(line);
	}
	return { ...offset, path: lines.join("") };
}

function transformedBox(box, matrix) {
	const [a, b, c, d, e, f] = matrix;
	const points = [[box.x, box.y], [box.x + box.width, box.y], [box.x, box.y + box.height], [box.x + box.width, box.y + box.height]]
		.map(([x, y]) => [a * x + c * y + e, b * x + d * y + f]);
	const x = Math.min(...points.map(p => p[0])), y = Math.min(...points.map(p => p[1]));
	return { x, y, width: Math.max(...points.map(p => p[0])) - x, height: Math.max(...points.map(p => p[1])) - y };
}

function cropBox(box, bounds, dx, dy, corner) {
	if (!corner) return { ...box, x: Math.max(bounds.x, Math.min(box.x + dx, bounds.x + bounds.width - box.width)),
		y: Math.max(bounds.y, Math.min(box.y + dy, bounds.y + bounds.height - box.height)) };
	const next = reshapeBox({ geometry: box }, dx, dy, corner, false);
	const x = Math.max(bounds.x, next.x), y = Math.max(bounds.y, next.y);
	return { x, y, width: Math.min(bounds.x + bounds.width, next.x + next.width) - x,
		height: Math.min(bounds.y + bounds.height, next.y + next.height) - y };
}

export function constrainedPoint(from, to, shape, shift) {
	let dx = to.x - from.x, dy = to.y - from.y;
	if (shift && shape === "line") {
		const directions = [[1, 0], [1, 1], [0, 1], [-1, 1], [-1, 0], [-1, -1], [0, -1], [1, -1]];
		const [x, y] = directions[(Math.round(Math.atan2(dy, dx) / (Math.PI / 4)) + 8) % 8];
		const length = (dx * x + dy * y) / (x * x + y * y);
		dx = x * length;
		dy = y * length;
	} else if (shift) {
		const size = Math.max(Math.abs(dx), Math.abs(dy));
		dx = (dx < 0 ? -1 : 1) * size;
		dy = (dy < 0 ? -1 : 1) * size;
	}
	return { x: from.x + dx, y: from.y + dy };
}

export function reshapeBox(item, dx, dy, handle, shift) {
	const box = item.geometry;
	if (!dx && !dy && !shift) return { ...box };
	if (item.shape === "line") {
		const start = { x: box.x, y: box.y }, end = { x: box.x + box.width, y: box.y + box.height };
		const fixed = handle === "start" ? end : start, moving = handle === "start" ? start : end;
		const point = constrainedPoint(fixed, { x: moving.x + dx, y: moving.y + dy }, "line", shift);
		const from = handle === "start" ? point : fixed, to = handle === "start" ? fixed : point;
		return from.x === to.x && from.y === to.y ? null
			: { x: from.x, y: from.y, width: to.x - from.x, height: to.y - from.y };
	}
	if (shift && handle.length === 2) {
		const change = objectTransform(box, dx, dy, handle);
		return { x: box.x + change.x, y: box.y + change.y, width: box.width * change.scale, height: box.height * change.scale };
	}
	let x = box.x, y = box.y, right = x + box.width, bottom = y + box.height;
	const minWidth = Math.min(1, box.width), minHeight = Math.min(1, box.height);
	if (handle.includes("w")) x = Math.min(x + dx, right - minWidth);
	if (handle.includes("e")) right = Math.max(right + dx, x + minWidth);
	if (handle.includes("n")) y = Math.min(y + dy, bottom - minHeight);
	if (handle.includes("s")) bottom = Math.max(bottom + dy, y + minHeight);
	return { x, y, width: right - x, height: bottom - y };
}

function paintShape(node, shape, box) {
	const { x, y, width, height } = box;
	const attributes = shape === "line" ? { x1: x, y1: y, x2: x + width, y2: y + height }
		: shape === "ellipse" ? { cx: x + width / 2, cy: y + height / 2, rx: width / 2, ry: height / 2 }
		: { x, y, width, height };
	for (const [key, value] of Object.entries(attributes)) {
		node.setAttribute(key, value);
	}
}

export function canEditObject(item, capability) {
	return Boolean(item) && (item.items || [item]).every(object => Boolean(object.capabilities?.[capability]));
}

export function objectEditReason(item) {
	const reasons = (item?.items || (item ? [item] : [])).map(object => {
		const reason = object.capabilities?.reason || "";
		if (!reason) return "";
		let message = "对象特性暂不支持";
		if (reason.includes("embedded font")) message = "缺少内嵌字体";
		else if (reason.includes("does not contain")) message = "字体缺字";
		else if (reason.includes("color") || reason.includes("RGB")) message = "颜色样式暂不支持";
		else if (reason.includes("draw parameter")) message = "绘制参数暂不支持";
		else if (reason.includes("layer")) message = "图层特性暂不支持";
		else if (reason.includes("container")) message = "容器特性暂不支持";
		else if (reason.includes("invalid")) message = "对象数据异常";
		return `${object.capabilities.transform ? "部分操作受限" : "暂不可编辑"}：${message}`;
	});
	return [...new Set(reasons.filter(Boolean))].join("；");
}

export class CanvasEditor {
	constructor(viewer, options) {
		this.viewer = viewer;
		this.options = options;
		this.enabled = false;
		this.selected = null;
		this.multiple = false;
		this.nodes = new WeakMap();
		this.pages = new WeakMap();
		this.tool = "";
		viewer.addEventListener("pointerdown", (event) => this.start(event));
		viewer.addEventListener("pointermove", (event) => this.move(event));
		viewer.addEventListener("pointerup", (event) => this.end(event));
		viewer.addEventListener("pointercancel", () => this.cancel());
		viewer.addEventListener("lostpointercapture", () => this.cancel());
		viewer.addEventListener("keydown", (event) => this.keyDown(event));
		viewer.addEventListener("keyup", (event) => this.modifierChange(event));
		viewer.addEventListener("dblclick", (event) => {
			const item = this.selected;
			if (!event.altKey && this.enabled && item && !item.items && !this.input && !this.options.busy()) {
				this.options.onEdit(item);
			}
		});
		viewer.addEventListener("scroll", () => this.cancel());
		window.addEventListener("blur", () => this.cancel());
		window.addEventListener("resize", () => this.cancel());
	}

	setEnabled(enabled) {
		this.enabled = enabled;
		this.viewer.classList.toggle("editing-select", enabled);
		if (!enabled) {
			this.setTool("");
			this.clear();
		}
	}

	setTool(tool) {
		this.cancel();
		this.tool = tool;
		this.viewer.classList.toggle("editing-draw", Boolean(tool));
		if (tool) {
			this.select(null);
		}
		this.options.onTool?.(tool);
	}

	mount(index, page, surface) {
		const crop = this.crop?.item.index === index ? this.crop : null;
		if (crop) this.closeCrop(true);
		const pending = this.pendingSelection?.index === index;
		const selected = pending ? this.pendingSelection.ids || page.objects.slice(-1).map(item => item.id)
			: this.items().filter(item => item.index === index).map(item => item.id);
		const selection = [];
		this.pages.set(surface, { index, width: page.width, height: page.height });
		const layer = document.createElement("div");
		layer.className = "edit-layer";
		for (const object of page.objects) {
			const node = document.createElement("div");
			node.className = "edit-object";
			node.classList.toggle("read-only", !canEditObject(object, "transform"));
			node.title = objectEditReason(object);
			if (object.shape === "line") {
				node.classList.add("edit-line");
			}
			node.tabIndex = 0;
			node.setAttribute("role", "button");
			node.setAttribute("aria-label", { ImageObject: "图片对象", TextObject: "文字对象", PathObject: "图形对象" }[object.type]);
			const item = { ...object, index, page: { width: page.width, height: page.height }, node, surface };
			this.nodes.set(node, item);
			node.addEventListener("focus", () => this.select(item));
			const handles = !canEditObject(object, "transform") ? [] : object.shape === "line" ? ["start", "end"]
				: object.shape ? ["nw", "n", "ne", "e", "se", "s", "sw", "w"]
					: object.type === "TextObject" && canEditObject(object, "reflow") && canEditObject(object, "layoutKnown")
						? ["nw", "ne", "e", "se", "sw", "w"] : ["nw", "ne", "sw", "se"];
			for (const corner of handles) {
				const handle = document.createElement("span");
				handle.className = `edit-handle edit-${corner}`;
				handle.dataset.corner = corner;
				node.append(handle);
			}
			this.place(item);
			layer.append(node);
			if (selected.includes(object.id)) {
				selection.push(item);
			}
		}
		surface.append(layer);
		if (selected.length) this.setSelection(selection);
		if (pending) this.pendingSelection = null;
		if (crop && selection.length === 1 && selection[0].id === crop.item.id
			&& ["x", "y", "width", "height"].every(key => selection[0][key] === crop.item[key])) {
			this.startCrop(selection[0], crop.pagePreview);
			this.crop.box = { ...crop.box };
			this.paintCrop();
		} else if (crop) {
			crop.pagePreview.urls.forEach(url => URL.revokeObjectURL(url));
		}
	}

	place(item, change = { x: 0, y: 0, scale: 1 }) {
		if (item.items) {
			for (const member of item.items) this.place(member, {
				x: change.x + (member.x - item.x) * (change.scale - 1),
				y: change.y + (member.y - item.y) * (change.scale - 1), scale: change.scale,
			});
		}
		if (item.shape) {
			this.placeShape(item, { x: item.geometry.x + change.x + (item.geometry.x - item.x) * (change.scale - 1),
				y: item.geometry.y + change.y + (item.geometry.y - item.y) * (change.scale - 1),
				width: item.geometry.width * change.scale, height: item.geometry.height * change.scale });
			return;
		}
		Object.assign(item.node.style, {
			left: `${(item.x + change.x) * PX_PER_MM}px`, top: `${(item.y + change.y) * PX_PER_MM}px`,
			width: `${item.width * change.scale * PX_PER_MM}px`, height: `${item.height * change.scale * PX_PER_MM}px`,
		});
		if (item.textFrame) {
			const { matrix: [a, b, c, d, e, f], width, height } = item.textFrame;
			for (const handle of item.node.children) {
				if (handle.dataset.corner !== "w" && handle.dataset.corner !== "e") continue;
				const x = handle.dataset.corner === "e" ? width : 0;
				handle.style.left = `${(a * x + c * height / 2 + e - item.x) * change.scale * PX_PER_MM}px`;
				handle.style.top = `${(b * x + d * height / 2 + f - item.y) * change.scale * PX_PER_MM}px`;
				handle.style.cursor = a === 0 ? "var(--resize-vertical, ns-resize)" : "var(--resize-horizontal, ew-resize)";
			}
		}
	}

	placeShape(item, box) {
		const x = Math.min(box.x, box.x + box.width), y = Math.min(box.y, box.y + box.height);
		Object.assign(item.node.style, {
			left: `${x * PX_PER_MM}px`, top: `${y * PX_PER_MM}px`,
			width: `${Math.abs(box.width) * PX_PER_MM}px`, height: `${Math.abs(box.height) * PX_PER_MM}px`,
		});
		if (item.shape === "line") {
			for (const handle of item.node.children) {
				const end = handle.dataset.corner === "end";
				handle.style.left = `${(box.x + (end ? box.width : 0) - x) * PX_PER_MM}px`;
				handle.style.top = `${(box.y + (end ? box.height : 0) - y) * PX_PER_MM}px`;
			}
		}
	}

	items() {
		return this.selected?.items || (this.selected ? [this.selected] : []);
	}

	setSelection(items) {
		const previous = this.selected;
		if (this.crop && (items.length !== 1 || items[0] !== this.crop.item)) this.closeCrop();
		if (this.selected?.items) this.selected.node.remove();
		for (const item of this.items()) {
			item.node.classList.remove("selected", "multi-selected");
			item.node.setAttribute("aria-pressed", "false");
		}
		this.selected = items.length < 2 ? items[0] || null : { ...selectionBounds(items), items,
			id: items.map(item => item.id), index: items[0].index, page: items[0].page, surface: items[0].surface };
		if (items.length > 1) {
			const node = document.createElement("div");
			node.className = "edit-layer edit-selection";
			for (const corner of canEditObject(this.selected, "transform") ? ["nw", "ne", "sw", "se"] : []) {
				const handle = document.createElement("span");
				handle.className = `edit-handle edit-${corner}`;
				handle.dataset.corner = corner;
				node.append(handle);
			}
			this.selected.node = node;
			this.nodes.set(node, this.selected);
			this.place(this.selected);
			this.selected.surface.append(node);
		}
		for (const item of items) {
			item.node.classList.add("selected");
			item.node.classList.toggle("multi-selected", items.length > 1);
			item.node.setAttribute("aria-pressed", "true");
		}
		this.options.onSelect(this.selected, previous);
	}

	select(item, add = false) {
		if (!add || !item || this.selected && item.index !== this.selected.index) {
			this.setSelection(item ? [item] : []);
			return;
		}
		const items = this.items();
		this.setSelection(items.includes(item) ? items.filter(member => member !== item) : [...items, item]);
	}

	clear() {
		this.closeText();
		this.closeCrop();
		this.cancel();
		this.pendingSelection = null;
		this.select(null);
	}

	start(event) {
		if (this.input) {
			if (event.target !== this.input.input) this.commitText();
			return;
		}
		if (!this.enabled || this.options.busy() || event.button !== 0 || this.drag) {
			return;
		}
		if (this.crop) {
			if (!event.target.closest(".edit-crop")) {
				this.commitCrop();
				return;
			}
			event.preventDefault();
			this.viewer.focus({ preventScroll: true });
			const { item, box } = this.crop;
			this.drag = { crop: true, box: { ...box }, pointerID: event.pointerId, corner: event.target.dataset.corner || "",
				page: item.page, rect: item.surface.getBoundingClientRect(), rotation: this.options.rotation(), clientX: event.clientX, clientY: event.clientY };
			this.viewer.setPointerCapture(event.pointerId);
			return;
		}
		if (this.tool) {
			if (this.tool.startsWith("erase-")) this.startErase(event);
			else this.startShape(event);
			return;
		}
		if (event.altKey && !event.shiftKey && !event.ctrlKey && !event.metaKey && !event.target.dataset.corner) {
			this.cycleSelection(event);
			return;
		}
		const node = event.target.closest(".edit-object, .edit-selection");
		if (node) {
			event.preventDefault();
		}
		this.viewer.focus({ preventScroll: true });
		const target = node ? this.nodes.get(node) : null;
		const additive = event.shiftKey || event.ctrlKey || event.metaKey || this.multiple;
		if (!target) {
			this.startMarquee(event, additive);
			return;
		}
		if (additive && !event.target.dataset.corner) {
			this.select(target, true);
			return;
		}
		if (target !== this.selected && !this.items().includes(target)) this.select(target);
		if (!node || this.options.busy()) {
			return;
		}
		const item = this.selected;
		if (!canEditObject(item, "transform")) return;
		this.drag = {
			item, pointerID: event.pointerId, corner: !item.items || target === item ? event.target.dataset.corner || "" : "",
			rect: item.surface.getBoundingClientRect(), rotation: this.options.rotation(),
			clientX: event.clientX, clientY: event.clientY,
		};
		if (!this.drag.corner) {
			const selected = this.items();
			this.drag.targets = [...item.surface.querySelectorAll(".edit-object")]
				.map(node => this.nodes.get(node)).filter(member => !selected.includes(member));
			this.drag.targets.push({ x: 0, y: 0, ...item.page });
		}
		if (item.shape === "line" && this.drag.corner) {
			Object.assign(this.drag, this.createPreview(item.surface, item.page, item.shape, {
				fill: false, stroke: true, strokeColor: "var(--accent)", lineWidth: item.lineWidth,
			}));
		}
		this.viewer.setPointerCapture(event.pointerId);
	}

	cycleSelection(event) {
		const surface = event.target.closest(".page-surface");
		const page = this.pages.get(surface);
		if (!page) return;
		const point = pagePoint(event.clientX, event.clientY, surface.getBoundingClientRect(), page, this.options.rotation());
		const items = [...surface.querySelectorAll(".edit-object")].map(node => this.nodes.get(node)).reverse()
			.filter(item => point.x >= item.x && point.x <= item.x + item.width && point.y >= item.y && point.y <= item.y + item.height);
		if (!items.length) return;
		event.preventDefault();
		this.viewer.focus({ preventScroll: true });
		this.select(items[(items.indexOf(this.selected) + 1) % items.length]);
	}

	move(event) {
		const drag = this.drag;
		if (!drag || drag.pointerID !== event.pointerId) {
			return;
		}
		event.preventDefault();
		drag.pointer = event;
		if (drag.erase) {
			this.moveErase(event, drag);
			return;
		}
		if (drag.crop) {
			const from = pagePoint(drag.clientX, drag.clientY, drag.rect, drag.page, drag.rotation);
			const to = pagePoint(event.clientX, event.clientY, drag.rect, drag.page, drag.rotation);
			this.crop.box = cropBox(drag.box, this.crop.item.imageBounds, to.x - from.x, to.y - from.y, drag.corner);
			this.paintCrop();
			return;
		}
		if (drag.shape) {
			this.moveShape(event, drag);
			return;
		}
		if (drag.marquee) {
			this.moveMarquee(event, drag);
			return;
		}
		if (!drag.change && !drag.box && Math.hypot(event.clientX - drag.clientX, event.clientY - drag.clientY) < 3) {
			return;
		}
		const from = pagePoint(drag.clientX, drag.clientY, drag.rect, drag.item.page, drag.rotation);
		const to = pagePoint(event.clientX, event.clientY, drag.rect, drag.item.page, drag.rotation);
		if (drag.item.type === "TextObject" && (drag.corner === "w" || drag.corner === "e")) {
			if (drag.item.textFrame) {
				const frame = drag.item.textFrame, [a, b, c, d] = frame.matrix;
				const dx = (d * (to.x - from.x) - c * (to.y - from.y)) / (a * d - b * c);
				const box = reshapeBox({ geometry: { x: 0, y: 0, width: frame.width, height: frame.height } }, dx, 0, drag.corner, false);
				drag.box = { x: drag.item.x + box.x, width: box.width };
				const bounds = transformedBox(box, frame.matrix);
				Object.assign(drag.item.node.style, { left: `${bounds.x * PX_PER_MM}px`, top: `${bounds.y * PX_PER_MM}px`,
					width: `${bounds.width * PX_PER_MM}px`, height: `${bounds.height * PX_PER_MM}px` });
				return;
			}
			drag.box = reshapeBox({ geometry: drag.item }, to.x - from.x, 0, drag.corner, false);
			Object.assign(drag.item.node.style, { left: `${drag.box.x * PX_PER_MM}px`, width: `${drag.box.width * PX_PER_MM}px` });
			return;
		}
		if (drag.item.shape && drag.corner) {
			drag.box = reshapeBox(drag.item, to.x - from.x, to.y - from.y, drag.corner, event.shiftKey);
			this.placeShape(drag.item, drag.box || drag.item.geometry);
			if (drag.node) paintShape(drag.node, drag.item.shape, drag.box || drag.item.geometry);
			return;
		}
		drag.change = objectTransform(drag.item, to.x - from.x, to.y - from.y, drag.corner);
		if (!drag.corner) this.snap(drag, event.altKey);
		this.place(drag.item, drag.change);
	}

	snap(drag, bypass = false) {
		const { item, rect, rotation, change } = drag;
		const { x, y, path } = bypass ? { x: 0, y: 0, path: "" } : alignmentSnap({ ...item, x: item.x + change.x, y: item.y + change.y }, drag.targets, {
			x: 4 * item.page.width / (rotation % 180 ? rect.height : rect.width),
			y: 4 * item.page.height / (rotation % 180 ? rect.width : rect.height),
		});
		change.x += x;
		change.y += y;
		if (!drag.guides && path) {
			drag.guides = this.createPreview(item.surface, item.page, "path", {
				fill: false, stroke: true, strokeColor: "var(--accent)", lineWidth: 1,
			});
			drag.guides.node.setAttribute("vector-effect", "non-scaling-stroke");
			drag.guides.node.setAttribute("stroke-dasharray", "4 3");
		}
		drag.guides?.node.setAttribute("d", path);
	}

	end(event) {
		const drag = this.drag;
		if (!drag || drag.pointerID !== event.pointerId) {
			return;
		}
		this.move(event);
		if (drag.erase) {
			const items = drag.erase === "erase-object" ? [...drag.erased] : drag.box
				? drag.items.filter(item => item.x < drag.box.x + drag.box.width && item.x + item.width > drag.box.x
					&& item.y < drag.box.y + drag.box.height && item.y + item.height > drag.box.y) : [];
			this.cancel();
			if (items.length && (!drag.points || drag.points.length >= 3)) this.options.onErase(items, drag.box, drag.points);
			return;
		}
		if (drag.crop) {
			this.drag = null;
			this.viewer.releasePointerCapture(drag.pointerID);
			return;
		}
		if (drag.marquee) {
			this.drag = null;
			drag.preview.remove();
			this.viewer.releasePointerCapture(drag.pointerID);
			return;
		}
		if (drag.shape) {
			this.drag = null;
			this.viewer.releasePointerCapture(drag.pointerID);
			if (drag.shape === "text") {
				const from = pagePoint(drag.clientX, drag.clientY, drag.rect, drag.page, drag.rotation);
				const x = Math.max(0, Math.min(from.x, drag.page.width - 1));
				const y = Math.max(0, Math.min(from.y, drag.page.height - 1));
				const box = drag.box || { x, y, width: Math.min(80, drag.page.width - x), height: 5 };
				drag.preview.remove();
				this.setTool("");
				this.options.onDrawText(drag.page.index, box, drag.surface, drag.page);
				return;
			}
			if (!drag.box) {
				drag.preview.remove();
				return;
			}
			this.setTool("");
			Promise.resolve(this.options.onDraw(drag.page.index, drag.shape, drag.box, drag.style))
				.finally(() => drag.preview.remove());
			return;
		}
		if ((drag.item.shape || drag.item.type === "TextObject") && drag.corner && drag.box) {
			this.drag = null;
			this.viewer.releasePointerCapture(drag.pointerID);
			const geometry = drag.item.geometry || (drag.item.textFrame ? { x: drag.item.x, width: drag.item.textFrame.width } : drag.item);
			const changed = Object.keys(drag.box).some((key) => drag.box[key] !== geometry[key]);
			const apply = drag.item.shape ? this.options.onReshape : this.options.onTextWidth;
			Promise.resolve(changed && apply(drag.item, drag.box)).finally(() => {
				drag.preview?.remove();
				this.place(drag.item);
			});
			return;
		}
		this.cancel();
		if (drag.change && (drag.change.x || drag.change.y || drag.change.scale !== 1)) {
			this.options.onTransform(drag.item, drag.change);
		}
	}

	cancel() {
		const drag = this.drag;
		this.drag = null;
		if (drag) {
			for (const item of drag.erased || []) item.node.classList.remove("erasing");
			if (drag.crop) {
				this.crop.box = drag.box;
				this.paintCrop();
			}
			drag.preview?.remove();
			drag.guides?.preview.remove();
			if (drag.marquee) this.setSelection(drag.before);
			if (drag.item) {
				this.place(drag.item);
			}
			if (this.viewer.hasPointerCapture(drag.pointerID)) {
				this.viewer.releasePointerCapture(drag.pointerID);
			}
		}
	}

	startErase(event) {
		const surface = event.target.closest(".page-surface") || this.nearestSurface(event);
		const page = this.pages.get(surface);
		if (!page) return;
		event.preventDefault();
		this.viewer.focus({ preventScroll: true });
		this.drag = { erase: this.tool, page, surface, items: [...surface.querySelectorAll(".edit-object")].map(node => this.nodes.get(node)),
			erased: new Set(), shape: "rectangle", pointerID: event.pointerId, clientX: event.clientX, clientY: event.clientY,
			rect: surface.getBoundingClientRect(), rotation: this.options.rotation() };
		if (this.tool === "erase-region") Object.assign(this.drag, this.createPreview(surface, page, "rectangle",
			{ fill: true, fillColor: "var(--accent-soft)", stroke: true, strokeColor: "var(--accent)", lineWidth: 0.2 }));
		if (this.tool === "erase-path") {
			Object.assign(this.drag, this.createPreview(surface, page, "path",
				{ fill: true, fillColor: "var(--accent-soft)", stroke: true, strokeColor: "var(--accent)", lineWidth: 0.2 }), { points: [] });
			this.drag.node.setAttribute("fill-rule", "evenodd");
		}
		this.viewer.setPointerCapture(event.pointerId);
		this.moveErase(event, this.drag);
	}

	moveErase(event, drag) {
		if (drag.erase === "erase-region") { this.moveShape(event, drag); return; }
		const point = pagePoint(event.clientX, event.clientY, drag.rect, drag.page, drag.rotation);
		if (drag.points) {
			const last = drag.lastPointer;
			if (last && Math.hypot(event.clientX - last.x, event.clientY - last.y) < 2) return;
			drag.lastPointer = { x: event.clientX, y: event.clientY };
			drag.points.push(point);
			const box = drag.box || { x: point.x, y: point.y, width: 0, height: 0 };
			const right = Math.max(box.x + box.width, point.x), bottom = Math.max(box.y + box.height, point.y);
			drag.box = { x: Math.min(box.x, point.x), y: Math.min(box.y, point.y) };
			Object.assign(drag.box, { width: right - drag.box.x, height: bottom - drag.box.y });
			drag.node.setAttribute("d", drag.points.map((point, index) => `${index ? "L" : "M"}${point.x} ${point.y}`).join(" ") + " Z");
			return;
		}
		const item = [...drag.items].reverse().find(item => point.x >= item.x && point.x <= item.x + item.width
			&& point.y >= item.y && point.y <= item.y + item.height);
		if (item) { drag.erased.add(item); item.node.classList.add("erasing"); }
	}

	startMarquee(event, additive) {
		const surface = event.target.closest(".page-surface"), page = this.pages.get(surface);
		if (!page) {
			this.select(null);
			return;
		}
		event.preventDefault();
		const before = this.items();
		const base = additive ? before.filter(item => item.index === page.index) : [];
		this.setSelection(base);
		this.drag = { marquee: true, page, surface, before, base,
			...this.createPreview(surface, page, "rectangle", { fill: true, fillColor: "var(--accent-soft)", stroke: true, strokeColor: "var(--accent)", lineWidth: 0.2 }),
			pointerID: event.pointerId, clientX: event.clientX, clientY: event.clientY,
			rect: surface.getBoundingClientRect(), rotation: this.options.rotation() };
		this.viewer.setPointerCapture(event.pointerId);
	}

	moveMarquee(event, drag) {
		const from = pagePoint(drag.clientX, drag.clientY, drag.rect, drag.page, drag.rotation);
		const to = pagePoint(event.clientX, event.clientY, drag.rect, drag.page, drag.rotation);
		const box = { x: Math.min(from.x, to.x), y: Math.min(from.y, to.y), width: Math.abs(to.x-from.x), height: Math.abs(to.y-from.y) };
		paintShape(drag.node, "rectangle", box);
		if (Math.hypot(event.clientX-drag.clientX, event.clientY-drag.clientY) < 3) return;
		const items = [...drag.base];
		for (const node of drag.surface.querySelectorAll(".edit-object")) {
			const item = this.nodes.get(node);
			if (!items.includes(item) && item.x <= box.x+box.width && item.x+item.width >= box.x && item.y <= box.y+box.height && item.y+item.height >= box.y) {
				items.push(item);
			}
		}
		this.setSelection(items);
	}

	startShape(event) {
		const surface = event.target.closest(".page-surface") || (this.tool !== "text" && this.nearestSurface(event));
		const page = this.pages.get(surface);
		if (!page || !this.options.canInsert(page.index)) {
			return;
		}
		event.preventDefault();
		this.viewer.focus({ preventScroll: true });
		const shape = this.tool;
		const style = this.options.drawStyle();
		if (shape === "line") {
			style.fill = false;
			style.stroke = true;
		}
		this.drag = { shape, page, surface, ...this.createPreview(surface, page, shape === "text" ? "rectangle" : shape, style), style, pointerID: event.pointerId,
			rect: surface.getBoundingClientRect(), rotation: this.options.rotation(),
			clientX: event.clientX, clientY: event.clientY };
		this.viewer.setPointerCapture(event.pointerId);
	}

	nearestSurface(event) {
		let nearest = null, distance = Infinity;
		for (const surface of this.viewer.querySelectorAll(".page-surface")) {
			if (!this.pages.has(surface)) continue;
			const rect = surface.getBoundingClientRect();
			const next = Math.hypot(Math.max(rect.left - event.clientX, 0, event.clientX - rect.right),
				Math.max(rect.top - event.clientY, 0, event.clientY - rect.bottom));
			if (next < distance) {
				nearest = surface;
				distance = next;
			}
		}
		return nearest;
	}

	createPreview(surface, page, shape, style) {
		const preview = document.createElementNS("http://www.w3.org/2000/svg", "svg");
		preview.classList.add("edit-preview");
		preview.setAttribute("viewBox", `0 0 ${page.width} ${page.height}`);
		const node = document.createElementNS("http://www.w3.org/2000/svg", shape === "rectangle" ? "rect" : shape);
		node.setAttribute("fill", style.fill ? style.fillColor : "none");
		node.setAttribute("stroke", style.stroke ? style.strokeColor : "none");
		node.setAttribute("stroke-width", style.lineWidth);
		preview.append(node);
		surface.append(preview);
		return { preview, node };
	}

	moveShape(event, drag) {
		const point = (x, y) => {
			const p = pagePoint(x, y, drag.rect, drag.page, drag.rotation);
			return drag.shape === "text" ? { x: Math.max(0, Math.min(p.x, drag.page.width)), y: Math.max(0, Math.min(p.y, drag.page.height)) } : p;
		};
		const from = point(drag.clientX, drag.clientY);
		const to = constrainedPoint(from, point(event.clientX, event.clientY), drag.shape, event.shiftKey && drag.shape !== "text");
		const x = Math.min(from.x, to.x), y = Math.min(from.y, to.y);
		const width = Math.abs(to.x - from.x), height = drag.shape === "text" ? Math.max(5, Math.abs(to.y - from.y)) : Math.abs(to.y - from.y);
		const valid = Math.hypot(event.clientX - drag.clientX, event.clientY - drag.clientY) >= 3
			&& (drag.shape === "line" ? width > 0 || height > 0 : width > 0 && height > 0);
		drag.box = valid ? drag.shape === "line"
			? { x: from.x, y: from.y, width: to.x - from.x, height: to.y - from.y }
			: { x, y, width, height } : null;
		paintShape(drag.node, drag.shape === "text" ? "rectangle" : drag.shape, drag.shape === "line"
			? { x: from.x, y: from.y, width: to.x - from.x, height: to.y - from.y } : { x, y, width, height });
	}

	modifierChange(event) {
		const pointer = this.drag?.pointer;
		if ((event.key === "Shift" || event.key === "Alt") && pointer) {
			this.move({ pointerId: pointer.pointerId, clientX: pointer.clientX, clientY: pointer.clientY,
				shiftKey: event.shiftKey, altKey: event.altKey, preventDefault() {} });
		}
	}

	keyDown(event) {
		if (event.defaultPrevented || event.target?.closest("input, textarea, select, [contenteditable]")) return;
		if (this.crop && !this.options.busy()) {
			if (event.key === "Escape" || event.key === "Enter") {
				event.preventDefault();
				event.stopPropagation();
				if (event.key === "Enter") this.commitCrop();
				else if (this.drag) this.cancel();
				else this.closeCrop();
			}
			return;
		}
		this.modifierChange(event);
		if (event.key === "Escape" && this.drag && !this.tool && !this.options.busy()) {
			event.preventDefault();
			event.stopPropagation();
			this.cancel();
			return;
		}
		if (event.key === "Escape" && this.tool && !this.options.busy()) {
			event.preventDefault();
			event.stopPropagation();
			this.setTool("");
			return;
		}
		if (this.input || !this.enabled || !this.selected || this.options.busy() || event.ctrlKey || event.metaKey || event.altKey || event.isComposing) {
			return;
		}
		const directions = { ArrowLeft: [-1, 0], ArrowRight: [1, 0], ArrowUp: [0, -1], ArrowDown: [0, 1] };
		const edit = event.key === "Enter" || event.key === "F2";
		if (event.key !== "Escape" && event.key !== "Delete" && !edit && !directions[event.key]) {
			return;
		}
		event.preventDefault();
		event.stopPropagation();
		if (event.key === "Escape") {
			this.drag ? this.cancel() : this.clear();
		} else if (event.key === "Delete" && canEditObject(this.selected, "delete")) {
			this.options.onDelete(this.selected);
		} else if (edit && !this.drag && !this.selected.items) {
			this.options.onEdit(this.selected);
		} else if (!this.drag && directions[event.key] && canEditObject(this.selected, "transform")) {
			const [x, y] = directions[event.key];
			const [dx, dy] = [[x, y], [y, -x], [-x, -y], [-y, x]][this.options.rotation() / 90];
			const step = event.shiftKey ? 10 : 1;
			this.options.onTransform(this.selected, { x: dx * step, y: dy * step, scale: 1 });
		}
	}

	editText(item, face) {
		this.cancel();
		this.closeText();
		this.select(item);
		document.fonts.add(face);
		const input = document.createElement("textarea");
		input.className = "edit-text";
		input.setAttribute("aria-label", "编辑文字");
		input.wrap = item.wrap ? "soft" : "off";
		input.spellcheck = false;
		input.value = item.text;
		Object.assign(input.style, {
			left: `${item.x * PX_PER_MM}px`, top: `${item.y * PX_PER_MM}px`,
			width: `${(item.wrap ? item.width : Math.max(item.width, Math.min(50, item.page.width - item.x))) * PX_PER_MM + 4}px`,
			minHeight: `${item.height * PX_PER_MM + 4}px`,
			fontFamily: `"${face.family}"`, fontSize: `${item.size * PX_PER_MM}px`,
			lineHeight: item.paragraphHeight || item.lineHeight ? `${(item.paragraphHeight || item.lineHeight) * PX_PER_MM}px` : "normal", color: item.color,
			textAlign: item.align || "left",
			letterSpacing: `${(item.letterSpacing || 0) * PX_PER_MM}px`,
		});
		if (item.textFrame) {
			const { width, height, matrix: [a, b, c, d, e, f] } = item.textFrame;
			Object.assign(input.style, { left: "0px", top: "0px", width: `${Math.max(width, item.wrap ? width : 50) * PX_PER_MM + 4}px`,
				minHeight: `${height * PX_PER_MM + 4}px`, transform: `matrix(${a},${b},${c},${d},${e * PX_PER_MM},${f * PX_PER_MM})` });
		}
		this.input = { input, item, face, fontChoice: item.fontChoice };
		item.surface.append(input);
		input.addEventListener("input", () => {
			this.resizeText();
			this.options.onTextChange();
		});
		input.addEventListener("blur", (event) => {
			if (!this.options.fontControls?.includes(event.relatedTarget)) this.commitText();
		});
		input.addEventListener("keydown", (event) => {
			if ((event.ctrlKey || event.metaKey) && !event.altKey && !event.shiftKey && event.key.toLowerCase() === "s") return;
			event.stopPropagation();
			if (event.isComposing || input.readOnly) {
				return;
			}
			if (event.key === "Escape") {
				event.preventDefault();
				this.closeText();
				this.viewer.focus({ preventScroll: true });
			} else if (event.key === "Enter" && (event.ctrlKey || event.metaKey)) {
				event.preventDefault();
				this.commitText();
			}
		});
		this.resizeText();
		input.focus({ preventScroll: true });
		if (!item.draft) input.select();
	}

	resizeText() {
		const { input } = this.input;
		input.style.height = "0px";
		input.style.height = `${input.scrollHeight + 2}px`;
	}

	setTextFont(face, data) {
		const editing = this.input;
		document.fonts.add(face);
		document.fonts.delete(editing.face);
		editing.face = face;
		editing.fontData = data;
		editing.input.style.fontFamily = `"${face.family}"`;
		this.resizeText();
		this.options.onTextChange();
		editing.input.focus({ preventScroll: true });
	}

	async commitText() {
		const editing = this.input;
		if (!editing) return true;
		if (editing.input.readOnly) return false;
		if (editing.input.value === editing.item.text && !editing.fontData || editing.item.draft && !editing.input.value.trim()) {
			this.closeText();
			return true;
		}
		editing.input.readOnly = true;
		const saved = await this.options.onCommitText(editing.item, editing.input.value, editing.fontData);
		if (this.input !== editing) {
			return Boolean(saved);
		}
		if (saved) {
			this.closeText();
		} else {
			editing.input.readOnly = false;
			editing.input.focus({ preventScroll: true });
		}
		return Boolean(saved);
	}

	closeText() {
		const editing = this.input;
		this.input = null;
		if (editing) {
			editing.input.remove();
			document.fonts.delete(editing.face);
			if (editing.item.draft && this.selected === editing.item) this.select(null);
			this.options.onTextChange();
		}
	}

	startCrop(item, pagePreview) {
		this.cancel();
		this.closeCrop();
		this.setTool("");
		const bounds = item.imageBounds;
		const x = Math.max(item.x, bounds.x), y = Math.max(item.y, bounds.y);
		const box = { x, y, width: Math.min(item.x + item.width, bounds.x + bounds.width) - x,
			height: Math.min(item.y + item.height, bounds.y + bounds.height) - y };
		const original = item.surface.querySelector(".ofd-svg");
		original.replaceWith(pagePreview.svg);
		const { preview, node: mask } = this.createPreview(item.surface, item.page, "path", { fill: true, fillColor: "rgba(255,255,255,0.72)" });
		mask.setAttribute("fill-rule", "evenodd");
		const node = document.createElement("div");
		node.className = "edit-layer edit-crop";
		for (const corner of ["nw", "n", "ne", "e", "se", "s", "sw", "w"]) {
			const handle = document.createElement("span");
			handle.className = `edit-handle edit-${corner}`;
			handle.dataset.corner = corner;
			node.append(handle);
		}
		item.surface.append(node);
		item.surface.classList.add("cropping");
		this.crop = { item, box, initialBox: { ...box }, node, mask, preview, original, pagePreview };
		this.paintCrop();
		this.viewer.focus({ preventScroll: true });
	}

	paintCrop() {
		const { item, box, node, mask } = this.crop;
		const rectangle = b => `M${b.x} ${b.y}h${b.width}v${b.height}h${-b.width}Z`;
		mask.setAttribute("d", rectangle(item.imageBounds) + rectangle(box));
		Object.assign(node.style, { left: `${box.x * PX_PER_MM}px`, top: `${box.y * PX_PER_MM}px`, width: `${box.width * PX_PER_MM}px`, height: `${box.height * PX_PER_MM}px` });
		this.options.onCropChange();
	}

	cropChanged() {
		return Boolean(this.crop && ["x", "y", "width", "height"].some(key => this.crop.box[key] !== this.crop.initialBox[key]));
	}

	async commitCrop() {
		if (!this.crop) return true;
		if (this.options.busy()) return false;
		if (!this.cropChanged()) {
			this.closeCrop();
			return true;
		}
		const crop = this.crop;
		const saved = await this.options.onCrop(crop.item, crop.box);
		if (saved && this.crop === crop) this.closeCrop();
		return Boolean(saved);
	}

	closeCrop(keepPreview = false) {
		if (!this.crop) return;
		if (this.drag?.crop) this.cancel();
		const crop = this.crop;
		this.crop = null;
		crop.node.remove();
		crop.preview.remove();
		crop.pagePreview.svg.replaceWith(crop.original);
		if (!keepPreview) crop.pagePreview.urls.forEach(url => URL.revokeObjectURL(url));
		crop.item.surface.classList.remove("cropping");
		this.options.onCropChange();
	}
}