'use strict';

const React = require("react");
const createReactClass = require("create-react-class");
const throttleit = require("throttleit");
const euclideanDistance = require("euclidean-distance");

const Window = require("./window");

module.exports = createReactClass({
	displayName: "WindowManager",
	getDefaultProps: function () {
		return {
			windowMoveThreshold: 6
		};
	},
	getInitialState: function () {
		return {
			movingWindow: null,
			activeWindow: null,
			windowPositions: {}
		};
	},
	lastMousePositionX: null,
	lastMousePositionY: null,
	componentDidMount: function () {
		/* Due to how synthetic events work in React, we need to separate out the 'get coordinates from event' and 'do something with the coordinates' step; if we throttle the coordinate extraction logic, we'll run into problems when synthetic events have already been cleared for reuse by the time we try to obtain the coordinates. Therefore, `processMouseMove` contains all the throttled logic, whereas the coordinate extraction happens on *every* mousemove event. */
		this.processMouseMove = throttleit(() => {
			/* Yes, the below check is there for a reason; just in case the `movingWindow` state changes between the call to the throttled wrapper and the wrapped function itself. */
			if (this.state.movingWindow != null) {
				let thresholdMet = this.state.movingWindowThresholdMet;

				/* Since we're outside of a React-controlled handler, we can't rely on React to batch updates. Therefore, we have to do our own impromptu batching. */
				let stateToUpdate = {};

				if (thresholdMet === false) {
					let origin = [this.state.movingWindowOriginX, this.state.movingWindowOriginY];
					let position = [this.lastMousePositionX, this.lastMousePositionY];

					if (euclideanDistance(origin, position) > this.props.windowMoveThreshold) {
						thresholdMet = true;
						stateToUpdate.thresholdMet = true;
					}
				}

				if (thresholdMet === true) {
					/* TODO: Consider handling this move out-of-band, to avoid going through React's rendering cycle for every move event. */
					stateToUpdate.windowPositions = Object.assign(this.state.windowPositions, {
						[this.state.movingWindow]: {
							x: this.lastMousePositionX - this.state.movingWindowBarX,
							y: this.lastMousePositionY - this.state.movingWindowBarY
						}
					});
				}

				/* FIXME: Move this into the store? */
				this.setState(stateToUpdate);
			}
		}, 10);
	},
	handleMouseMove: function(event) {
		if (this.state.movingWindow != null) {
			this.lastMousePositionX = event.pageX;
			this.lastMousePositionY = event.pageY;
			this.processMouseMove();
		}
	},
	handleMouseUp: function () {
		this.setState({
			movingWindow: null
		});
	},
	handleTitleMouseDown: function (window, event, barX, barY) {
		this.setState({
			movingWindow: window.id,
			movingWindowThresholdMet: false,
			movingWindowBarX: barX,
			movingWindowBarY: barY,
			movingWindowOriginX: event.pageX,
			movingWindowOriginY: event.pageY
		});
	},
	render: function () {
		/* TODO: Tiled layout */

		return (
			<div className="windowManager" onMouseMove={this.handleMouseMove} onMouseUp={this.handleMouseUp}>
				{this.props.children}
				{this.props.store.getAll().toArray().map((window_) => {
					let x, y;

					let overrideWindowPosition = this.state.windowPositions[window_.id];

					if (overrideWindowPosition != null) {
						x = overrideWindowPosition.x;
						y = overrideWindowPosition.y;
					} else {
						x = window_.initialX;
						y = window_.initialY;
					}

					let windowStyle = {
						transform: `translate(${x}px, ${y}px)`,
						width: window_.width,
						height: window_.height,
						zIndex: window_.zIndex
					};

					let handlers = {
						onTitleMouseDown: (...args) => {
							return this.handleTitleMouseDown(window_, ...args);
						},
						onMouseDown: () => {
							this.props.store.focus(window_.id);
						},
						onClose: () => {
							this.props.store.close(window_.id);
						}
					};

					return (<Window key={window_.id} style={windowStyle} title={window_.title} isActive={window_.isActive} {...handlers}>
						{window_.contents}
					</Window>);
				})}
			</div>
		);
	}
});