io.github.oliviercailloux.gitjfs.impl.QueryUtils Maven / Gradle / Ivy

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package io.github.oliviercailloux.gitjfs.impl;

import com.google.common.base.Strings;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Iterables;
import com.google.common.net.PercentEscaper;
import java.net.URI;
import java.net.URLDecoder;
import java.nio.charset.StandardCharsets;
import java.util.AbstractMap.SimpleImmutableEntry;
import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

class QueryUtils {
  public static final PercentEscaper QUERY_ENTRY_ESCAPER =
      new PercentEscaper("-_.*~!$'(),;@:/+?", false);
  private static final PercentEscaper RESTRICTED_ESCAPER = new PercentEscaper("-_.*%", false);

  /**
   * Thanks to https://stackoverflow.com/a/13592567/.
   */
  public static Map splitQuery(URI uri) {
    if (Strings.isNullOrEmpty(uri.getRawQuery())) {
      return Collections.emptyMap();
    }
    final Map> asLists =
        Arrays.stream(uri.getRawQuery().split("&")).map(QueryUtils::splitQueryParameter)
            .collect(Collectors.groupingBy(SimpleImmutableEntry::getKey, LinkedHashMap::new,
                Collectors.mapping(Map.Entry::getValue, Collectors.toList())));

    if (asLists.keySet().stream().anyMatch(k -> asLists.get(k).size() >= 2)) {
      throw new IllegalArgumentException();
    }
    return asLists.keySet().stream().collect(
        ImmutableMap.toImmutableMap(k -> k, k -> Iterables.getOnlyElement(asLists.get(k))));
  }

  /**
   * Thanks to https://stackoverflow.com/a/13592567/.
   */
  private static SimpleImmutableEntry splitQueryParameter(String it) {
    final int idx = it.indexOf("=");
    final String key = idx > 0 ? it.substring(0, idx) : it;
    final String value = idx > 0 && it.length() > idx + 1 ? it.substring(idx + 1) : null;
    /*
     * Because URLDecoder only decodes very restricted strings, I need to encode a bit more before
     * decoding. Importantly, I need to encode plus, otherwise converted back to space instead of
     * left alone. But I need to leave % alone as this indicates a percent-escape, not a percent
     * sign. Sob.
     */
    final String decodedKey =
        URLDecoder.decode(RESTRICTED_ESCAPER.escape(key), StandardCharsets.UTF_8);
    final String decodedValue =
        URLDecoder.decode(RESTRICTED_ESCAPER.escape(value), StandardCharsets.UTF_8);
    return new SimpleImmutableEntry<>(decodedKey, decodedValue);
  }
}