com.sap.cds.adapter.odata.v4.metadata.provider.EdmxI18nInputStream Maven / Gradle / Ivy

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OData V4 adapter for CDS Services Java

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/**************************************************************************
 * (C) 2019-2024 SAP SE or an SAP affiliate company. All rights reserved. *
 **************************************************************************/
package com.sap.cds.adapter.odata.v4.metadata.provider;

import java.io.BufferedInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import com.google.common.xml.XmlEscapers;

class EdmxI18nInputStream extends InputStream {

	private static final int[] IPATTERN = new int[] { '{', 'i', '1', '8', 'n', '>' };

	private final Map i18n;
	private final Map escapedI18n;

	private final BufferedInputStream buffer;
	private byte[] replacement;
	private int replacementOffset;

	public EdmxI18nInputStream(InputStream is, Map i18n) {
		buffer = new BufferedInputStream(is);
		if (i18n == null) {
			this.i18n = Collections.emptyMap();
			this.escapedI18n = Collections.emptyMap();
		} else {
			this.i18n = i18n;
			this.escapedI18n = new HashMap<>(); // no need to replace all keys every time
		}
	}

	@Override
	public int read() throws IOException {

		// if replacement available read replacement bytes
		if (replacement != null) {
			if (replacementOffset < replacement.length) {
				return replacement[replacementOffset++] & 0xff;
			}
			replacement = null;
		}

		if (lookAhead()) {
			return read();
		}

		return buffer.read();
	}

	private boolean lookAhead() throws IOException {
		buffer.mark(IPATTERN.length);

		// detect pattern
		for (int i = 0; i < IPATTERN.length; i++) {
			if (buffer.read() != IPATTERN[i]) {
				buffer.reset();
				return false;
			}
		}

		// get the i18n key
		int cc;
		ByteArrayOutputStream result = new ByteArrayOutputStream();
		while ((cc = buffer.read()) >= 0) {
			if (cc == '}') {
				// get i18n value
				String i18nKey = result.toString(StandardCharsets.UTF_8);
				replacementOffset = 0;

				if (!i18n.containsKey(i18nKey)) {
					buffer.reset();
					return false;
				}

				replacement = escapedI18n.computeIfAbsent(i18nKey, k -> {
					String raw = i18n.get(k);
					return raw != null ? XmlEscapers.xmlAttributeEscaper().escape(raw) : null;
				}).getBytes(StandardCharsets.UTF_8);
				return true;
			}
			result.write(cc);
		}

		buffer.reset();
		return false;
	}

}