/*******************************************************************************
 * Copyright (c) 2016 EclipseSource.
 *
 * Distributed under MIT license
 * See https://github.com/ralfstx/minimal-json/blob/master/LICENSE
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 ******************************************************************************/
package net.sourceforge.plantuml.json;

import java.io.IOException;
import java.io.Writer;

class JsonWriter {

	private static final int CONTROL_CHARACTERS_END = 0x001f;

	private static final char[] QUOT_CHARS = { '\\', '"' };
	private static final char[] BS_CHARS = { '\\', '\\' };
	private static final char[] LF_CHARS = { '\\', 'n' };
	private static final char[] CR_CHARS = { '\\', 'r' };
	private static final char[] TAB_CHARS = { '\\', 't' };
	// In JavaScript, U+2028 and U+2029 characters count as line endings and must be
	// encoded.
	// http://stackoverflow.com/questions/2965293/javascript-parse-error-on-u2028-unicode-character
	private static final char[] UNICODE_2028_CHARS = { '\\', 'u', '2', '0', '2', '8' };
	private static final char[] UNICODE_2029_CHARS = { '\\', 'u', '2', '0', '2', '9' };
	private static final char[] HEX_DIGITS = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd',
			'e', 'f' };

	protected final Writer writer;

	JsonWriter(Writer writer) {
		this.writer = writer;
	}

	protected void writeLiteral(String value) throws IOException {
		writer.write(value);
	}

	protected void writeNumber(String string) throws IOException {
		writer.write(string);
	}

	protected void writeString(String string) throws IOException {
		writer.write('"');
		writeJsonString(string);
		writer.write('"');
	}

	protected void writeArrayOpen() throws IOException {
		writer.write('[');
	}

	protected void writeArrayClose() throws IOException {
		writer.write(']');
	}

	protected void writeArraySeparator() throws IOException {
		writer.write(',');
	}

	protected void writeObjectOpen() throws IOException {
		writer.write('{');
	}

	protected void writeObjectClose() throws IOException {
		writer.write('}');
	}

	protected void writeMemberName(String name) throws IOException {
		writer.write('"');
		writeJsonString(name);
		writer.write('"');
	}

	protected void writeMemberSeparator() throws IOException {
		writer.write(':');
	}

	protected void writeObjectSeparator() throws IOException {
		writer.write(',');
	}

	protected void writeJsonString(String string) throws IOException {
		int length = string.length();
		int start = 0;
		for (int index = 0; index < length; index++) {
			char[] replacement = getReplacementChars(string.charAt(index));
			if (replacement != null) {
				writer.write(string, start, index - start);
				writer.write(replacement);
				start = index + 1;
			}
		}
		writer.write(string, start, length - start);
	}

	private static char[] getReplacementChars(char ch) {
		if (ch > '\\') {
			if (ch < '\u2028' || ch > '\u2029') {
				// The lower range contains 'a' .. 'z'. Only 2 checks required.
				return null;
			}
			return ch == '\u2028' ? UNICODE_2028_CHARS : UNICODE_2029_CHARS;
		}
		if (ch == '\\') {
			return BS_CHARS;
		}
		if (ch > '"') {
			// This range contains '0' .. '9' and 'A' .. 'Z'. Need 3 checks to get here.
			return null;
		}
		if (ch == '"') {
			return QUOT_CHARS;
		}
		if (ch > CONTROL_CHARACTERS_END) {
			return null;
		}
		if (ch == '\n') {
			return LF_CHARS;
		}
		if (ch == '\r') {
			return CR_CHARS;
		}
		if (ch == '\t') {
			return TAB_CHARS;
		}
		return new char[] { '\\', 'u', '0', '0', HEX_DIGITS[ch >> 4 & 0x000f], HEX_DIGITS[ch & 0x000f] };
	}

}
