/*
 * [The "BSD license"]
 *  Copyright (c) 2011 Terence Parr
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 *  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 *  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 *  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.stringtemplate.v4;

import java.io.IOException;
import java.io.Writer;
import java.util.ArrayList;
import java.util.List;
import java.util.Stack;

Essentially a char filter that knows how to auto-indent output by maintaining
a stack of indent levels.

The indent stack is a stack of strings so we can repeat original indent not
just the same number of columns (don't have to worry about tabs vs spaces
then). Anchors are char positions (tabs won't work) that indicate where all
future wraps should justify to. The wrap position is actually the larger of
either the last anchor or the indentation level.
 This is a filter on a Writer.
 \n is the proper way to say newline for options and templates. Templates can mix \r\n and \n them, but use \n in options like wrap="\n". This writer will render newline characters according to newline. The default value is taken from the line.separator system property, and can be overridden by passing in a String to the appropriate constructor.
/**
 * Essentially a char filter that knows how to auto-indent output by maintaining
 * a stack of indent levels.
 * <p>
 * The indent stack is a stack of strings so we can repeat original indent not
 * just the same number of columns (don't have to worry about tabs vs spaces
 * then). Anchors are char positions (tabs won't work) that indicate where all
 * future wraps should justify to. The wrap position is actually the larger of
 * either the last anchor or the indentation level.</p>
 * <p>
 * This is a filter on a {@link Writer}.</p>
 * <p>
 * {@code \n} is the proper way to say newline for options and templates.
 * Templates can mix {@code \r\n} and {@code \n} them, but use {@code \n} in
 * options like {@code wrap="\n"}. This writer will render newline characters
 * according to {@link #newline}. The default value is taken from the
 * {@code line.separator} system property, and can be overridden by passing in a
 * {@code String} to the appropriate constructor.</p>
 */
public class AutoIndentWriter implements STWriter {
	
Stack of indents. Use List as it's much faster than Stack. Grows from 0..n-1. /** Stack of indents. Use {@link List} as it's much faster than {@link Stack}. Grows
	 *  from 0..n-1.
	 */
	public List<String> indents = new ArrayList<String>();

	
Stack of integer anchors (char positions in line); avoid Integer creation overhead. /** Stack of integer anchors (char positions in line); avoid {@link Integer}
	 *  creation overhead.
	 */
	public int[] anchors = new int[10];
	public int anchors_sp = -1;

	
\n or \r\n? /** {@code \n} or {@code \r\n}? */
	public String newline;

	public Writer out = null;
    public boolean atStartOfLine = true;

	
Track char position in the line (later we can think about tabs). Indexed from 0. We want to keep charPosition <= lineWidth. This is the position we are about to write, not the position
last written to.
/**
	 * Track char position in the line (later we can think about tabs). Indexed
	 * from 0. We want to keep {@code charPosition <= }{@link #lineWidth}.
	 * This is the position we are <em>about</em> to write, not the position
	 * last written to.
	 */
    public int charPosition = 0;

    
The absolute char index into the output of the next char to be written. /** The absolute char index into the output of the next char to be written. */
    public int charIndex = 0;

	public int lineWidth = NO_WRAP;

	public AutoIndentWriter(Writer out, String newline) {
		this.out = out;
		indents.add(null); // s oftart with no indent
		this.newline = newline;
	}

	public AutoIndentWriter(Writer out) {
		this(out, System.getProperty("line.separator"));
	}

	@Override
	public void setLineWidth(int lineWidth) {
		this.lineWidth = lineWidth;
	}

	@Override
    public void pushIndentation(String indent) {
        indents.add(indent);
    }

	@Override
    public String popIndentation() {
        return indents.remove(indents.size()-1);
    }

	@Override
	public void pushAnchorPoint() {
		if ( (anchors_sp +1)>=anchors.length ) {
			int[] a = new int[anchors.length*2];
			System.arraycopy(anchors, 0, a, 0, anchors.length-1);
			anchors = a;
		}
		anchors_sp++;
		anchors[anchors_sp] = charPosition;
	}

	@Override
	public void popAnchorPoint() {
		anchors_sp--;
	}

	@Override
    public int index() { return charIndex; }

	
Write out a string literal or attribute expression or expression element. /** Write out a string literal or attribute expression or expression element. */
	@Override
	public int write(String str) throws IOException {
		int n = 0;
		int nll = newline.length();
		int sl = str.length();
		for (int i=0; i<sl; i++) {
			char c = str.charAt(i);
			// found \n or \r\n newline?
			if ( c=='\r' ) continue;
            if ( c=='\n' ) {
				atStartOfLine = true;
				charPosition = -nll; // set so the write below sets to 0
				out.write(newline);
				n += nll;
				charIndex += nll;
				charPosition += n; // wrote n more char
				continue;
			}
			// normal character
			// check to see if we are at the start of a line; need indent if so
			if ( atStartOfLine ) {
                n+=indent();
                atStartOfLine = false;
			}
			n++;
			out.write(c);
			charPosition++;
			charIndex++;
		}
		return n;
	}

	@Override
    public int writeSeparator(String str) throws IOException {
		return write(str);
	}

	
Write out a string literal or attribute expression or expression element.
 If doing line wrap, then check wrap before emitting str. If at or beyond desired line width then emit a newline and any indentation before spitting out str.
/**
	 * Write out a string literal or attribute expression or expression element.
	 * <p>
	 * If doing line wrap, then check {@code wrap} before emitting {@code str}.
	 * If at or beyond desired line width then emit a {@link #newline} and any
	 * indentation before spitting out {@code str}.</p>
	 */
	@Override
	public int write(String str, String wrap) throws IOException {
		int n = writeWrap(wrap);
		return n + write(str);
	}

	@Override
	public int writeWrap(String wrap) throws IOException {
		int n = 0;
		// if want wrap and not already at start of line (last char was \n)
		// and we have hit or exceeded the threshold
		if ( lineWidth!=NO_WRAP && wrap!=null && !atStartOfLine &&
			 charPosition >= lineWidth )
		{
			// ok to wrap
			// Walk wrap string and look for A\nB.  Spit out A\n
			// then spit indent or anchor, whichever is larger
			// then spit out B.
			for (int i=0; i<wrap.length(); i++) {
				char c = wrap.charAt(i);
				if ( c=='\r' ) {
					continue;
				} else if ( c=='\n' ) {
					out.write(newline);
                    n += newline.length();
					charPosition = 0;
                    charIndex += newline.length();
                    n += indent();
					// continue writing any chars out
				}
				else {  // write A or B part
					n++;
					out.write(c);
					charPosition++;
                    charIndex++;
				}
			}
		}
		return n;
	}

	public int indent() throws IOException {
		int n = 0;
		for (String ind : indents) {
			if (ind != null) {
				n += ind.length();
				out.write(ind);
			}
		}

        // If current anchor is beyond current indent width, indent to anchor
        // *after* doing indents (might tabs in there or whatever)
        int indentWidth = n;
        if ( anchors_sp>=0 && anchors[anchors_sp]>indentWidth ) {
            int remainder = anchors[anchors_sp]-indentWidth;
            for (int i=1; i<=remainder; i++) out.write(' ');
            n += remainder;
        }

        charPosition += n;
        charIndex += n;
		return n;
	}
}