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// Copyright (c) 2003-present, Jodd Team (http://jodd.org)
// 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.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT HOLDER OR CONTRIBUTORS 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 jodd.util;

import java.util.Map;

/**
 * Parser for string macro templates. On parsing, macro values
 * in provided string are resolved and replaced with real values.
 * Once set, one string template parser can be reused for parsing,
 * even using different macro resolvers.
 */
public class StringTemplateParser {

	/**
	 * Static ctor.
	 */
	public static StringTemplateParser create() {
		return new StringTemplateParser();
	}

	public static final String DEFAULT_MACRO_PREFIX = "$";
	public static final String DEFAULT_MACRO_START = "${";
	public static final String DEFAULT_MACRO_END = "}";

	// ---------------------------------------------------------------- properties

	protected boolean replaceMissingKey = true;
	protected String missingKeyReplacement;
	protected boolean resolveEscapes = true;
	protected String macroPrefix = DEFAULT_MACRO_PREFIX;
	protected String macroStart = DEFAULT_MACRO_START;
	protected String macroEnd = DEFAULT_MACRO_END;
	protected char escapeChar = '\\';
	protected boolean parseValues;

	public boolean isReplaceMissingKey() {
		return replaceMissingKey;
	}

	/**
	 * Specifies if missing keys should be resolved at all,
	 * true by default.
	 * If false missing keys will be left as it were, i.e.
	 * they will not be replaced.
	 */
	public void setReplaceMissingKey(boolean replaceMissingKey) {
		this.replaceMissingKey = replaceMissingKey;
	}

	public String getMissingKeyReplacement() {
		return missingKeyReplacement;
	}

	/**
	 * Specifies replacement for missing keys. If null
	 * exception will be thrown.
	 */
	public StringTemplateParser setMissingKeyReplacement(String missingKeyReplacement) {
		this.missingKeyReplacement = missingKeyReplacement;
		return this;
	}

	public boolean isResolveEscapes() {
		return resolveEscapes;
	}

	/**
	 * Specifies if escaped values should be resolved. In special usecases,
	 * when the same string has to be processed more then once,
	 * this may be set to false so escaped values
	 * remains.
	 */
	public StringTemplateParser setResolveEscapes(boolean resolveEscapes) {
		this.resolveEscapes = resolveEscapes;
		return this;
	}

	public String getMacroStart() {
		return macroStart;
	}

	/**
	 * Defines macro start string.
	 */
	public StringTemplateParser setMacroStart(String macroStart) {
		this.macroStart = macroStart;
		return this;
	}

	public String getMacroPrefix() {
		return macroPrefix;
	}

	public StringTemplateParser setMacroPrefix(String macroPrefix) {
		this.macroPrefix = macroPrefix;
		return this;
	}

	public String getMacroEnd() {
		return macroEnd;
	}

	/**
	 * Defines macro end string.
	 */
	public StringTemplateParser setMacroEnd(String macroEnd) {
		this.macroEnd = macroEnd;
		return this;
	}

	/**
	 * Sets the strict format by setting the macro prefix to null.
	 */
	public StringTemplateParser setStrictFormat() {
		macroPrefix = null;
		return this;
	}

	public char getEscapeChar() {
		return escapeChar;
	}

	/**
	 * Defines escape character.
	 */
	public StringTemplateParser setEscapeChar(char escapeChar) {
		this.escapeChar = escapeChar;
		return this;
	}

	public boolean isParseValues() {
		return parseValues;
	}

	/**
	 * Defines if macro values has to be parsed, too.
	 * By default, macro values are returned as they are.
	 */
	public StringTemplateParser setParseValues(boolean parseValues) {
		this.parseValues = parseValues;
		return this;
	}


	// ---------------------------------------------------------------- parse

	/**
	 * Parses string template and replaces macros with resolved values.
	 */
	public String parse(String template, MacroResolver macroResolver) {
		StringBuilder result = new StringBuilder(template.length());

		int i = 0;
		int len = template.length();

		// strict flag means that start and end tag are not necessary
		boolean strict;

		if (macroPrefix == null) {
			// when prefix is not specified, make it equals to macro start
			// so we can use the same code
			macroPrefix = macroStart;

			strict = true;
		}
		else {
			strict = false;
		}

		int prefixLen = macroPrefix.length();
		int startLen = macroStart.length();
		int endLen = macroEnd.length();

		while (i < len) {
			int ndx = template.indexOf(macroPrefix, i);
			if (ndx == -1) {
				result.append(i == 0 ? template : template.substring(i));
				break;
			}

			// check escaped
			int j = ndx - 1;
			boolean escape = false;
			int count = 0;

			while ((j >= 0) && (template.charAt(j) == escapeChar)) {
				escape = !escape;
				if (escape) {
					count++;
				}
				j--;
			}
			if (resolveEscapes) {
				result.append(template.substring(i, ndx - count));
			} else {
				result.append(template.substring(i, ndx));
			}
			if (escape == true) {
				result.append(macroPrefix);

				i = ndx + prefixLen;

				continue;
			}

			// macro started, detect strict format

			boolean strictFormat = strict;

			if (strictFormat == false) {
				if (StringUtil.isSubstringAt(template, macroStart, ndx)) {
					strictFormat = true;
				}
			}

			int ndx1;
			int ndx2;

			if (!strictFormat) {
				// not strict format: $foo

				ndx += prefixLen;
				ndx1 = ndx;
				ndx2 = ndx;

				while ((ndx2 < len) && CharUtil.isPropertyNameChar(template.charAt(ndx2))) {
					ndx2++;
				}

				if (ndx2 == len) {
					ndx2--;
				}

				while ((ndx2 > ndx) && !CharUtil.isAlphaOrDigit(template.charAt(ndx2))) {
					ndx2--;
				}

				ndx2++;

				if (ndx2 == ndx1 + 1) {
					// no value, hence no macro
					result.append(macroPrefix);

					i = ndx1;
					continue;
				}
			}
			else {
				// strict format: ${foo}

				// find macros end
				ndx += startLen;
				ndx2 = template.indexOf(macroEnd, ndx);
				if (ndx2 == -1) {
					throw new IllegalArgumentException("Invalid template, unclosed macro at: " + (ndx - startLen));
				}

				// detect inner macros, there is no escaping
				ndx1 = ndx;
				while (ndx1 < ndx2) {
					int n = StringUtil.indexOf(template, macroStart, ndx1, ndx2);
					if (n == -1) {
						break;
					}
					ndx1 = n + startLen;
				}
			}

			final String name = template.substring(ndx1, ndx2);

			// find value and append

			Object value;
			if (missingKeyReplacement != null || replaceMissingKey == false) {
				try {
					value = macroResolver.resolve(name);
				} catch (Exception ignore) {
					value = null;
				}

				if (value == null) {
					if (replaceMissingKey == true) {
						value = missingKeyReplacement;
					} else {
						value = template.substring(ndx1 - startLen, ndx2 + 1);
					}
				}
			} else {
				value = macroResolver.resolve(name);
				if (value == null) {
					value = StringPool.EMPTY;
				}
			}

			if (ndx == ndx1) {
				String stringValue = value.toString();
				if (parseValues == true) {
					if (stringValue.contains(macroStart)) {
						stringValue = parse(stringValue, macroResolver);
					}
				}
				result.append(stringValue);

				i = ndx2;
				if (strictFormat) {
					i += endLen;
				}
			} else {
				// inner macro
				template = template.substring(0, ndx1 - startLen) + value.toString() + template.substring(ndx2 + endLen);
				len = template.length();
				i = ndx - startLen;
			}
		}
		return result.toString();
	}

	// ---------------------------------------------------------------- resolver

	/**
	 * Macro value resolver.
	 */
	public interface MacroResolver {
		/**
		 * Resolves macro value for macro name founded in
		 * string template. null values will
		 * be replaced with empty strings.
		 */
		String resolve(String macroName);

	}

	/**
	 * Creates commonly used {@link MacroResolver} that resolved
	 * macros in the provided map.
	 */
	public static MacroResolver createMapMacroResolver(final Map map) {
		return new MacroResolver() {
			public String resolve(String macroName) {
				Object value = map.get(macroName);

				if (value == null) {
					return null;
				}

				return value.toString();
			}
		};
	}

}