/*
 * $Id$
 * Copyright (C) 2001 The Apache Software Foundation. All rights reserved.
 * For details on use and redistribution please refer to the
 * LICENSE file included with these sources.
 */

package org.apache.fop.layoutmgr;


import org.apache.fop.fo.FObj;
import org.apache.fop.area.Area;
import org.apache.fop.area.LineArea;
import org.apache.fop.area.MinOptMax;
import org.apache.fop.area.inline.InlineArea;

import java.util.ListIterator;

/**
 * LayoutManager for lines. It builds one or more lines containing
 * inline areas generated by its sub layout managers.
 */
public class LineLayoutManager extends AbstractLayoutManager {
    /** Reference to FO whose areas it's managing or to the traits
     * of the FO.
     */
    private ListIterator fobjIter;
    private LineArea lineArea = null;
    private boolean bFirstLine;
    private LayoutManager curLM;
    private MinOptMax remainingIPD;

    public LineLayoutManager(ListIterator fobjIter) {
	super(null);
	this.fobjIter = fobjIter;
    }


    /**
     * Call child layout managers to generate content as long as they
     * generate inline areas. If a block-level generating LM is found,
     * finish any line being filled and return to the parent LM.
     */
    public void generateAreas() {
	this.bFirstLine = true;
	while (fobjIter.hasNext()) {
	    FObj childFO = (FObj)fobjIter.next();
	    if (childFO.generatesInlineAreas()==false) {
		// It generates blocks, pass back to parent
		// Back up one
		fobjIter.previous();
		break;
	    }
	    else { // generates inline area
		curLM = childFO.getLayoutManager();
		if (curLM != null) {
		    curLM.setParentLM(this);
		    curLM.generateAreas();
		}
	    }
	}
	flush(); // Add last area to parent
    }


    /**
     * Align and position curLine and add it to parentContainer.
     * Set curLine to null.
     */
    public void flush() {
	if (lineArea != null) {
	    // Adjust spacing as necessary
	    // Calculate height, based on content (or does the Area do this?)
	    parentLM.addChild(lineArea);
	    lineArea = null;
	}
    }


    /**
     * Return current lineArea or generate a new one if necessary.
     */
    public Area getParentArea(Area childArea) {
	if (lineArea == null) {
	    createLine();
	}
	return lineArea;
    }

    private void createLine() {
	lineArea = new LineArea();
	/* Set line IPD from parentArea
	 * This accounts for indents. What about first line indent?
	 * Should we set an "isFirst" flag on the lineArea to signal
	 * that to the parent (Block) LM? That's where indent property
	 * information will be managed.
	 */
	Area parent = parentLM.getParentArea(lineArea);
	// lineArea.setContentIPD(parent.getContentIPD());
	// remainingIPD = parent.getContentIPD();
	// OR???
	// remainingIPD = parentLM.getContentIPD();
	remainingIPD = new MinOptMax(100000);  // TESTING!!!
	this.bFirstLine = false;
    }


    /**
     * Called by child LayoutManager when it has filled one of its areas.
     * See if the area will fit in the current container.
     * If so, add it.
     * This should also handle floats if childArea is an anchor.
     * @param childArea the area to add: should be an InlineArea subclass!
     */
    public void addChild(Area childArea) {
	if ((childArea instanceof InlineArea)==false) {
	    // SIGNAL AN ERROR!!!
	    return;
	}
	InlineArea inlineArea = (InlineArea)childArea;
	if (lineArea == null) {
	    createLine();
	}
	if (inlineArea.getAllocationIPD().min < remainingIPD.max) {
	    lineArea.addInlineArea(inlineArea);
	    remainingIPD.subtract(inlineArea.getAllocationIPD());
	    // Calculate number of spaces
	    // Forced line break after this area (ex. ends with LF in nowrap)
	    /* NOTYET!
	    if (inlineArea.breakAfter()) {
		flush();
	    }
	    */
	    /* Check if line could end after this area (potential line-break
	     * character. If not, it must be joined with following inline
	     * area to make a word. Otherwise, if the line could break here
	     * and if it is "full", add it to the parent area.
	     */
	    if (remainingIPD.min<=0) {
		flush();
	    }
	}

	else {
	    /* The inline area won't entirely fit in this line. Ask its
	     * layout manager to split it (by hyphenation for example),
	     * in order to fit part of it in the line.
	     * Note: only the current child LM could have generated this
	     * area, so we ask it to do the split.
	     */
	    SplitContext splitContext = new SplitContext(remainingIPD);
	    if (curLM.splitArea(inlineArea, splitContext)) {
		// inlineArea should now fit
		lineArea.addInlineArea(inlineArea);
		flush();
	    }
	    addChild(splitContext.nextArea);
	}
    }

}