"use strict";

import cuid from "cuid";
import { simplify_line } from "visvalingam-simplifier";

import ChunkReference from './ChunkReference.js';
import Vector from './Utilities/Vector';
import Mouse from './Utilities/Mouse';

class Pencil
{
	/**
	 * Creates a new Pencil class instance.
	 * @param	{RippleLink}	inRippleLink	The connection to the nibri server.
	 * @return	{Pencil}		A new Pencil class instance.
	 */
	constructor(inRippleLink, inBoardWindow, inCanvas)
	{
		this.boardWindow = inBoardWindow;
		
		// The time, in milliseconds, between pushes of the line to the server.
		this.pushDelay = 200;
		
		// The current line width
		this.currentLineWidth = 3;
		// The current line colour
		this.currentColour = "black";
		
		/**
		 * The ripple link connection to the server.
		 * @type {RippleLink}
		 */
		this.rippleLink = inRippleLink;
		/**
		 * The mouse information.
		 * @type {Mouse}
		 */
		this.mouse = new Mouse();
		
		/** The id of the current line-in-progress.*/
		this.currentLineId = cuid();
		/** Holds the (unsimplified) line segments before the pencil is lifted. */
		this.currentLineSegments = [];
		/** Holds the (simplified) line segment befoer the pencil is lifted. */
		this.currentSimplifiedLineSegments = [];
		
		// The segments of the (unsimplified) line that haven't yet been sent
		// to the server.
		this.unsentSegments = [];
		
		// The time of the last push of the line to the server.
		this.lastServerPush = 0;
		
		this.canvas = inCanvas;
		
		// Event Listeners
		document.addEventListener("mousedown", this.handleMouseDown.bind(this));
		document.addEventListener("mousemove", this.handleMouseMove.bind(this));
		document.addEventListener("mouseup", this.handleMouseUp.bind(this));
		
		this.setupInterfaceBindings(this.boardWindow.interface);
		
		// Whether the pencil is on the board at the moment.
		this.pencilDown = false;
	}
	
	setupInterfaceBindings(inInterface)
	{
		// Snag the initial colour from the interface
		this.currentColour = inInterface.brushIndicator.colour;
		// Listen for future colour updates
		inInterface.on("colourchange", (function(event) {
		    this.currentColour = event.newColour;
		}).bind(this))
		
		// Look up the initial line with in the interface
		this.currentLineWidth = inInterface.brushIndicator.width;
		// Listen for future updates fromt he interface
		inInterface.on("brushwidthchange", (function(event) {
		    this.currentLineWidth = event.newWidth;
		}).bind(this))
	}
	
	handleMouseDown(event) {
		if(event.target != this.canvas)
			return;
		
		switch(this.boardWindow.interface.currentTool)
		{
			case "brush": // Put the pencil down and start the new line
				this.pencilDown = true;
				
				console.log(`Starting line with id ${this.currentLineId}.`);
				this.rippleLink.send({
					Event: "LineStart",
					LineId: this.currentLineId,
					LineColour: this.currentColour,
					LineWidth: this.currentLineWidth
				});
				break;
			
			case "eraser":
				// Put the pencil down, but don't tell the server since we're 
				// not drawing a line
				this.pencilDown = true;
				break;
		}
		
	}
	
	handleMouseMove(event) {
		// Don't handle mouse movements on anything other than the canvas itself
		if(event.target != this.canvas)
			return;
		
		switch(this.boardWindow.interface.currentTool)
		{
			case "brush":
				if(!this.pencilDown)
					return; // Don't draw anything if the left mouse button isn't down
					
				var nextPoint = new Vector(
					(event.clientX / this.boardWindow.viewport.zoomLevel) + this.boardWindow.viewport.x,
					(event.clientY / this.boardWindow.viewport.zoomLevel) + this.boardWindow.viewport.y
				);
				this.unsentSegments.push(nextPoint);
				this.currentLineSegments.push(nextPoint);
				
				this.recalculateSimplifiedLine();
				
				var timeSinceLastPush = new Date() - this.lastServerPush;
				if(timeSinceLastPush > this.pushDelay)
				this.sendUnsent();
				break;
			
			case "eraser":
				if(!this.pencilDown)
					return; // Only erase when the pencil is down
				
				let cursorPos = this.boardWindow.cursorSyncer.absCursorPosition;
				let hoverChunkRef = this.boardWindow.cursorSyncer.chunkRefUnderCursor;
				
				let hoverChunk = this.boardWindow.chunkCache.fetchChunk(hoverChunkRef);
				if(hoverChunk == null) {
					console.warn(`Can't erase on chunk ${hoverChunkRef} as it's currently not loaded.`);
					break; // If it's null, then we haven't received it yet from the server
				}
				
				let lineToErase = hoverChunk.getLineUnderPoint(cursorPos);
				if(lineToErase == null) {
					console.debug(`No line found at abs ${cursorPos}.`);
					break; // There's no line underneath the cursor atm
				}
				
				console.info(`[pencil] Erasing line with unique id ${lineToErase.UniqueId} from ${hoverChunkRef}.`);
				
				// Ask the server politely to remove the line
				this.rippleLink.send({
					Event: "LineRemove",
					ContainingChunk: hoverChunkRef,
					UniqueId: lineToErase.UniqueId
				});
				
				// Remove the line ourselves too to make the interface update faster
				hoverChunk.removeByUniqueId(lineToErase.UniqueId);
				break;
			
			case "pan":
				// handled by BoardWindow.handleCanvasMovement(event)
				break;
			
			case "pointer":
				// Don't need to do anything here!
				break;
			
			default:
				console.warn(`Unknown tool ${this.boardWindow.interface.currentTool}.`);
				break;
		}
		
	}
	
	handleMouseUp(event) {
		// Ignore it if the ctrl key is held down - see above
		if(this.boardWindow.keyboard.DownKeys.includes(17))
			return;
		
		switch(this.boardWindow.interface.currentTool)
		{
			case "brush":
				
				this.sendUnsent();
				// Tell the server that the line is complete
				this.rippleLink.send({
					Event: "LineComplete",
					LineId: this.currentLineId
				});
				
				this.pencilDown = false;
				
				// Reset the current line segments
				this.currentLineSegments = [];
				this.currentSimplifiedLineSegments = [];
				// Regenerate the line id
				this.currentLineId = cuid();
				
				break;
			
			case "eraser":
				this.pencilDown = false;
				
				break;
		}
	}
	
	/**
	 * Send the unsent segments of the line to the server and reset the line
	 * unsent segments buffer.
	 */
	sendUnsent() {
		// Don't bother if there aren't any segments to push
		if(this.unsentSegments.length == 0)
			return;
		
		// It's time for another push of the line to the server
		this.rippleLink.send({
			Event: "LinePart",
			Points: this.unsentSegments,
			LineId: this.currentLineId
		});
		// Reset the unsent segments buffer
		this.unsentSegments = [];
		// Update the time we last pushed to the server
		this.lastServerPush = +new Date();
	}
	
	/**
	 * Recalculates the simplified line points array.
	 */
	recalculateSimplifiedLine()
	{
		this.currentSimplifiedLineSegments = simplify_line(this.currentLineSegments, 6);
	}
	
	/**
	 * Renders the line that is currently being drawn to the screen.
	 * @param  {HTMLCanvasElement} canvas  The canvas to draw to.
	 * @param  {CanvasRenderingContext2D} context The rendering context to use to draw to the canvas.
	 */
	render(canvas, context) {
		if(this.currentSimplifiedLineSegments.length == 0)
			return;
		
		context.save();
		
		context.beginPath();
		context.moveTo(this.currentSimplifiedLineSegments[0].x, this.currentSimplifiedLineSegments[0].y);
		for(let i = 1; i < this.currentSimplifiedLineSegments.length; i++) {
			context.lineTo(this.currentSimplifiedLineSegments[i].x, this.currentSimplifiedLineSegments[i].y);
		}
		
		context.lineWidth = this.currentLineWidth;
		context.strokeStyle = this.currentColour;
		context.lineCap = "round";
		context.lineJoin = "round";
		context.stroke();
		
		context.restore();
	}
}

export default Pencil;