/*
 * Copyright 2008 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.zxing.qrcode;

import com.google.zxing.BarcodeFormat;
import com.google.zxing.EncodeHintType;
import com.google.zxing.Writer;
import com.google.zxing.WriterException;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.encoder.ByteMatrix;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;
import com.google.zxing.qrcode.encoder.Encoder;
import com.google.zxing.qrcode.encoder.QRCode;

import java.util.Map;

/**
 * This object renders a QR Code as a BitMatrix 2D array of greyscale values.
 * 
 * @author dswitkin@google.com (Daniel Switkin)
 */
public final class QRCodeWriter implements Writer {

	private static final int QUIET_ZONE_SIZE = 4;

	@Override
	public BitMatrix encode(String contents, BarcodeFormat format, int width, int height) throws WriterException {

		return encode(contents, format, width, height, null);
	}

	@Override
	public BitMatrix encode(String contents, BarcodeFormat format, int width, int height, Map<EncodeHintType, ?> hints)
			throws WriterException {

		if (contents.isEmpty()) {
			throw new IllegalArgumentException("Found empty contents");
		}

		if (format != BarcodeFormat.QR_CODE) {
			throw new IllegalArgumentException("Can only encode QR_CODE, but got " + format);
		}

		if (width < 0 || height < 0) {
			throw new IllegalArgumentException("Requested dimensions are too small: " + width + 'x' + height);
		}

		ErrorCorrectionLevel errorCorrectionLevel = ErrorCorrectionLevel.L;
		int quietZone = QUIET_ZONE_SIZE;
		if (hints != null) {
			ErrorCorrectionLevel requestedECLevel = (ErrorCorrectionLevel) hints.get(EncodeHintType.ERROR_CORRECTION);
			if (requestedECLevel != null) {
				errorCorrectionLevel = requestedECLevel;
			}
			Integer quietZoneInt = (Integer) hints.get(EncodeHintType.MARGIN);
			if (quietZoneInt != null) {
				quietZone = quietZoneInt;
			}
		}

		QRCode code = Encoder.encode(contents, errorCorrectionLevel, hints);
		return renderResult(code, width, height, quietZone);
	}

	// Note that the input matrix uses 0 == white, 1 == black, while the output
	// matrix uses
	// 0 == black, 255 == white (i.e. an 8 bit greyscale bitmap).
	private static BitMatrix renderResult(QRCode code, int width, int height, int quietZone) {
		ByteMatrix input = code.getMatrix();
		if (input == null) {
			throw new IllegalStateException();
		}
		int inputWidth = input.getWidth();
		int inputHeight = input.getHeight();
		int qrWidth = inputWidth + (quietZone * 2);
		int qrHeight = inputHeight + (quietZone * 2);
		int outputWidth = Math.max(width, qrWidth);
		int outputHeight = Math.max(height, qrHeight);

		int multiple = Math.min(outputWidth / qrWidth, outputHeight / qrHeight);
		// Padding includes both the quiet zone and the extra white pixels to
		// accommodate the requested
		// dimensions. For example, if input is 25x25 the QR will be 33x33
		// including the quiet zone.
		// If the requested size is 200x160, the multiple will be 4, for a QR of
		// 132x132. These will
		// handle all the padding from 100x100 (the actual QR) up to 200x160.
		int leftPadding = (outputWidth - (inputWidth * multiple)) / 2;
		int topPadding = (outputHeight - (inputHeight * multiple)) / 2;

		BitMatrix output = new BitMatrix(outputWidth, outputHeight);

		for (int inputY = 0, outputY = topPadding; inputY < inputHeight; inputY++, outputY += multiple) {
			// Write the contents of this row of the barcode
			for (int inputX = 0, outputX = leftPadding; inputX < inputWidth; inputX++, outputX += multiple) {
				if (input.get(inputX, inputY) == 1) {
					output.setRegion(outputX, outputY, multiple, multiple);
				}
			}
		}

		return output;
	}

}
