package org.expeditee.actions;

import java.awt.Color;
import java.util.Collection;
import java.util.LinkedList;
import java.util.List;

import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

import org.expeditee.gui.Frame;
import org.expeditee.gui.FrameIO;
import org.expeditee.gui.FrameUtils;
import org.expeditee.gui.MessageBay;
import org.expeditee.io.flowlayout.XGroupItem;
import org.expeditee.items.Item;
import org.expeditee.items.ItemUtils;
import org.expeditee.items.Text;

/**
 * Javascript parser.
 * Works differently to the other Javascript class in that it
 * parses a frame as a whole rather than parsing individual text items as separate statements
 * 
 * @author jts21
 */
public class Javascript2 {
	
	public static final String ERROR_FRAMESET = "JavascriptErrors";
	
	private static ScriptEngineManager sem = new ScriptEngineManager();
	private static ScriptEngine se = sem.getEngineByMimeType("application/javascript");
	
	public static synchronized void runFrame(Frame frame, boolean followLinks) throws Exception {
		Javascript2 js = new Javascript2(frame, followLinks);
		try {
            se.eval(js.toString());
        } catch (ScriptException e) {
        	int lineNumber = e.getLineNumber();
        	if(lineNumber != -1) {
        		CodeLine cl = js.lines.get(lineNumber - 1);
        		Frame errorSourceFrame = cl.item.getParent();
        		if(errorSourceFrame == null) {
        			throw new Exception("Failed to find frame on which error occurred");
        		}
        		Frame errorFrame;
        		String title = "Error parsing \"" + errorSourceFrame.getTitle() + "\" (" + errorSourceFrame.getName() + ")";
        		if(FrameIO.canAccessFrameset(ERROR_FRAMESET)) {
        			errorFrame = FrameIO.CreateFrame(ERROR_FRAMESET, title, null);
        		} else {
        			errorFrame = FrameIO.CreateFrameset(ERROR_FRAMESET, FrameIO.FRAME_PATH);
        			errorFrame.setTitle(title);
        		}
        		Collection<Item> toAdd = errorSourceFrame.getAllItems();
        		toAdd.remove(errorSourceFrame.getTitleItem());
        		toAdd.remove(cl.item);
        		errorFrame.addAllItems(ItemUtils.CopyItems(toAdd));
        		String errorItemText = cl.item.getText().trim();
        		String[] errorItemLines = errorItemText.split("[\\n|\\r]+");
        		int errorLinePos = 0;
        		for(int i = 0; i < cl.line; i++) {
        			errorLinePos += errorItemLines[i].length();
        		}
        		Text beforeErrorItem = errorFrame.addText(cl.item.getX(), cl.item.getY(),
        				errorItemText.substring(0, errorLinePos), null);
        		Text errorItem;
    			errorItem = errorFrame.addText(cl.item.getX(),
    					beforeErrorItem.getY() + beforeErrorItem.getBoundsHeight(), 
    					errorItemLines[cl.line], null);
    			errorItem.setBackgroundColor(Color.RED);
    			// todo set width to 80 characters worth
    			for(String line : e.getMessage().split("[\\n|\\r]+")) {
    				errorItem.setTooltip("text: " + line);
    			}
    			errorItem.setTooltip("font: " + Text.MONOSPACED_FONT);
    			errorItem.setTooltip("width: " + 80 * 12);
        		errorLinePos += errorItemLines[cl.line].length();
        		if(++errorLinePos < errorItemText.length()) {
        			errorFrame.addText(cl.item.getX(), errorItem.getY() + errorItem.getBoundsHeight(),
        					errorItemText.substring(errorLinePos + 1), null);
        		}
        		errorFrame.change();
        		FrameIO.SaveFrame(errorFrame);
        		MessageBay.displayMessage("Script failed at line " + lineNumber +  " - `" + cl.source + "`",
        				errorFrame.getName(), MessageBay.ERROR_COLOR, true, null);
        		FrameUtils.DisplayFrame(errorFrame, true, true);
        	}
        }
	}
	
	private static final class CodeLine {
		public Text item;
		public int line;
		public String source;
		
		public CodeLine(Text item, int line, String source) {
			this.item = item;
			this.line = line;
			this.source = source;
		}
	}
	
	private List<Frame> seen = new LinkedList<Frame>();
	private List<CodeLine> lines = new LinkedList<CodeLine>();
	private StringBuffer sb = new StringBuffer();
	private Javascript2(Frame frame, boolean followLinks) {
		this.parseFrame(frame, followLinks);
	}
	
	private void parseFrame(Frame frame, boolean followLinks) {
		if(frame == null) {
			return;
		}
		
		// make sure we don't get into an infinite loop
		// TODO: find a smarter way to do this that allows reusing frames but still stops infinite loops?
		seen.add(frame);
		
		// get all items on the frame
		List<Item> y_ordered_items = (List<Item>)frame.getItems();
		// remove the title item
		y_ordered_items.remove(frame.getTitleItem());
		
		XGroupItem toplevel_xgroup = new XGroupItem(frame,y_ordered_items);
		// ... following on from Steps 1 and 2 in the Constructor in XGroupItem ...
		
		// Step 3: Reposition any 'out-of-flow' XGroupItems
		toplevel_xgroup.repositionOutOfFlowGroups(toplevel_xgroup);
		
		// Step 4: Now add in the remaining (nested) XGroupItems
		List<XGroupItem> grouped_item_list = toplevel_xgroup.getGroupedItemList();
		toplevel_xgroup.mapInXGroupItemsRecursive(grouped_item_list);
	
		// Finally, retrieve linear list of all Items, (ordered, Y by X, allowing for overlap, nested-boxing, and arrow flow)
		List<Item> overlapping_y_ordered_items = toplevel_xgroup.getYXOverlappingItemList();	
		
		// Loop through the items looking for code and links to new frames
		for(Item i : overlapping_y_ordered_items) {
			if(followLinks && i.hasLink()) {
				Frame child = i.getChild();
				if(child != null && !seen.contains(child)) {
					this.parseFrame(child, true);
				}
			}
			if(i instanceof Text && !i.isAnnotation()) {
				String text = ((Text)i).getText();
				int lineNumber = 0;
				for(String line : text.trim().split("[\\n|\\r]+")) {
					sb.append(line).append("\n");
					lines.add(new CodeLine((Text)i, lineNumber++, line));
				}
			}
		}
	}
	
	public String toString() {
		return this.sb.toString();
	}

}