org.opentripplanner.standalone.config.IncludeFileDirective Maven / Gradle / Ivy

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package org.opentripplanner.standalone.config;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.commons.io.IOUtils;
import org.opentripplanner.util.OtpAppException;

/**
 * Replaces a file include directive with the text content of the file "as is". For example:
 *  * {
 *   "my-config" : "${includeFile:myConfig.json}"
 * }
 * 
 * The {@code ${includeFile:myConfig.json}} will tell the config parser to find the
 * myConfig.json in the local config directory and insert the content into the
 * configuration. This is done before the environment variables are resolved, enabling
 * environment variable replacement in the included file as well as the config file.
 */
class IncludeFileDirective {

    public static final String QUOTE = "\"";
    private final File configDir;

    private IncludeFileDirective(File configDir) {
        this.configDir = configDir;
    }

    /**
     * A pattern matching a placeholder like '${includeFile:my-own-config.json}'. The placeholder
     * must start with '${includeFile:' and end with '}'. The file name must consist of only
     * alphanumerical characters(a-z, A-Z, 0-9), dot '.', dash '-', and underscore '_'.
     */
    private final static Pattern INCLUDE_FILE_PATTERN = Pattern.compile("\"?\\$\\{includeFile:([-.\\w]+)}\"?");

    /**
     * Search for {@link #INCLUDE_FILE_PATTERN}s and replace each placeholder with the value of the
     * corresponding environment variable.
     *
     * @param source is used only to generate human friendly error message in case the text
     *               contain a placeholder whitch can not be found.
     * @throws IllegalArgumentException if a placeholder exist in the {@code text}, but the
     *                                  environment variable do not exist.
     */
    public static String includeFileDirective(File configDir, String text, String source) {
        return new IncludeFileDirective(configDir).includeFileDirective(text, source);
    }

    private String includeFileDirective(String text, String source) {
        Matcher matcher = INCLUDE_FILE_PATTERN.matcher(text);
        Map replacements = new HashMap<>();

        while (matcher.find()) {
            String directive = matcher.group(0);
            String fileName = matcher.group(1);
            File file = new File(configDir, fileName);

            if (!file.exists() || !file.canRead()) {
                throw new OtpAppException(
                        "The file is not found for directive '" + directive + "' in config '"
                                + source + "'."
                );
            }
            replacements.put(directive, file);
        }

        for (Entry entry : replacements.entrySet()) {
            String directive = entry.getKey();
            String fileText = loadFile(entry.getValue(), directive, source);

            // If the insert text is a legal JSON object "[white-space]{ ... }[white-space]", then
            // ignore the optional quotes matched by the directive pattern
            var json = fileText.trim();
            if(json.startsWith("{") && json.endsWith("}")) {
                text = text.replace(entry.getKey(), fileText);
            }
            else {
                // Add back quotes if matched part of directive pattern
                String startQuote = directive.startsWith(QUOTE) ? QUOTE : "";
                String endQuote = directive.endsWith(QUOTE) ? QUOTE : "";
                text = text.replace(entry.getKey(), startQuote + fileText + endQuote);
            }
        }
        return text;
    }

    private static String loadFile(File file, String directive, String source) {
        try {
            return IOUtils.toString(
                    new FileInputStream(file), StandardCharsets.UTF_8
            );
        }
        catch (FileNotFoundException ex) {
            throw new OtpAppException(
                    "File '{}' is not present. Can not include "
                    + "directive '{}' in config file '{}'.",
                    file.getPath(), directive, source
            );
        }
        catch (IOException e) {
            throw new OtpAppException(
                    "Error while parsing file '{}'. Can not include "
                    + "directive '{}' in config file '{}'.",
                    file.getPath(), directive, source
            );
        }
    }
}