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/*
* Copyright (c) 2021-2022 - Yupiik SAS - https://www.yupiik.com
* 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 io.yupiik.batch.runtime.util;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.function.Function;
import static java.util.Optional.ofNullable;
public class Substitutor {
private static final char ESCAPE = '$';
private static final char[] PREFIX = "{".toCharArray();
private static final char[] SUFFIX = "}".toCharArray();
private static final char[] VALUE_DELIMITER = ":-".toCharArray();
private final Function valueMap;
public Substitutor(final Function valueMap) {
this.valueMap = valueMap;
}
public String replace(final String source) {
if (source == null) {
return null;
}
final StringBuilder builder = new StringBuilder(source);
if (substitute(builder, 0, source.length(), null) <= 0) {
return source;
}
return replace(builder.toString());
}
private int substitute(final StringBuilder buf, final int offset, final int inLength,
List priorVariables) {
final boolean top = priorVariables == null;
boolean altered = false;
int lengthChange = 0;
char[] chars = buf.toString().toCharArray();
int bufEnd = offset + inLength;
int pos = offset;
int length = inLength;
while (pos < bufEnd) {
final int startMatchLen = isMatch(PREFIX, chars, pos, bufEnd);
if (startMatchLen == 0) {
pos++;
} else {
if (pos > offset && chars[pos - 1] == ESCAPE) {
buf.deleteCharAt(pos - 1);
chars = buf.toString().toCharArray();
length = chars.length;
lengthChange--;
altered = true;
bufEnd--;
} else {
final int startPos = pos;
pos += startMatchLen;
int endMatchLen;
while (pos < bufEnd) {
endMatchLen = isMatch(SUFFIX, chars, pos, bufEnd);
if (endMatchLen == 0) {
pos++;
} else {
String varNameExpr = new String(chars, startPos
+ startMatchLen, pos - startPos
- startMatchLen);
pos += endMatchLen;
final int endPos = pos;
String varName = varNameExpr;
String varDefaultValue = null;
final char[] varNameExprChars = varNameExpr.toCharArray();
for (int i = 0; i < varNameExprChars.length; i++) {
if (isMatch(PREFIX, varNameExprChars, i, varNameExprChars.length) != 0) {
break;
}
final int match = isMatch(VALUE_DELIMITER, varNameExprChars, i, varNameExprChars.length);
if (match != 0) {
varName = varNameExpr.substring(0, i);
varDefaultValue = varNameExpr.substring(i + match);
break;
}
}
if (priorVariables == null) {
priorVariables = new ArrayList<>();
priorVariables.add(new String(chars, offset, length));
}
checkCyclicSubstitution(varName, priorVariables);
priorVariables.add(varName);
final String varValue = getOrDefault(varName, varDefaultValue);
if (varValue != null) {
final int varLen = varValue.length();
buf.replace(startPos, endPos, varValue);
altered = true;
int change = substitute(buf, startPos, varLen, priorVariables);
change = change + varLen - (endPos - startPos);
pos += change;
bufEnd += change;
lengthChange += change;
chars = buf.toString().toCharArray();
}
priorVariables.remove(priorVariables.size() - 1);
break;
}
}
}
}
}
if (top) {
return altered ? 1 : 0;
}
return lengthChange;
}
private String getOrDefault(final String varName, final String varDefaultValue) {
return ofNullable(valueMap.apply(varName)).orElse(varDefaultValue);
}
private int isMatch(final char[] chars, final char[] buffer, int pos,
final int bufferEnd) {
final int len = chars.length;
if (pos + len > bufferEnd) {
return 0;
}
for (int i = 0; i < chars.length; i++, pos++) {
if (chars[i] != buffer[pos]) {
return 0;
}
}
return len;
}
private void checkCyclicSubstitution(final String varName, final List priorVariables) {
if (!priorVariables.contains(varName)) {
return;
}
final StringBuilder buf = new StringBuilder(256);
buf.append("Infinite loop in property interpolation of ");
buf.append(priorVariables.remove(0));
buf.append(": ");
appendWithSeparators(buf, priorVariables);
throw new IllegalStateException(buf.toString());
}
private void appendWithSeparators(final StringBuilder builder, final Collection iterable) {
if (iterable != null && !iterable.isEmpty()) {
builder.append(String.join("->", iterable));
}
}
}
