/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.lucene.util.automaton;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import org.apache.lucene.tests.util.LuceneTestCase;
import org.apache.lucene.tests.util.TestUtil;
import org.apache.lucene.util.BytesRef;
import org.apache.lucene.util.BytesRefBuilder;

public class TestCompiledAutomaton extends LuceneTestCase {

  private CompiledAutomaton build(int determinizeWorkLimit, String... strings) {
    final List<BytesRef> terms = new ArrayList<>();
    for (String s : strings) {
      terms.add(new BytesRef(s));
    }
    Collections.sort(terms);
    final Automaton a = Automata.makeStringUnion(terms);
    return new CompiledAutomaton(a, true, false, determinizeWorkLimit, false);
  }

  private void testFloor(CompiledAutomaton c, String input, String expected) {
    final BytesRef b = new BytesRef(input);
    final BytesRef result = c.floor(b, new BytesRefBuilder());
    if (expected == null) {
      assertNull(result);
    } else {
      assertNotNull(result);
      assertEquals(
          "actual=" + result.utf8ToString() + " vs expected=" + expected + " (input=" + input + ")",
          result,
          new BytesRef(expected));
    }
  }

  private void testTerms(int determinizeWorkLimit, String[] terms) throws Exception {
    final CompiledAutomaton c = build(determinizeWorkLimit, terms);
    final BytesRef[] termBytes = new BytesRef[terms.length];
    for (int idx = 0; idx < terms.length; idx++) {
      termBytes[idx] = new BytesRef(terms[idx]);
    }
    Arrays.sort(termBytes);

    if (VERBOSE) {
      System.out.println("\nTEST: terms in unicode order");
      for (BytesRef t : termBytes) {
        System.out.println("  " + t.utf8ToString());
      }
      // System.out.println(c.utf8.toDot());
    }

    for (int iter = 0; iter < 100 * RANDOM_MULTIPLIER; iter++) {
      final String s =
          random().nextInt(10) == 1 ? terms[random().nextInt(terms.length)] : randomString();
      if (VERBOSE) {
        System.out.println("\nTEST: floor(" + s + ")");
      }
      int loc = Arrays.binarySearch(termBytes, new BytesRef(s));
      final String expected;
      if (loc >= 0) {
        expected = s;
      } else {
        // term doesn't exist
        loc = -(loc + 1);
        if (loc == 0) {
          expected = null;
        } else {
          expected = termBytes[loc - 1].utf8ToString();
        }
      }
      if (VERBOSE) {
        System.out.println("  expected=" + expected);
      }
      testFloor(c, s, expected);
    }
  }

  public void testRandom() throws Exception {
    final int numTerms = atLeast(400);
    final Set<String> terms = new HashSet<>();
    while (terms.size() != numTerms) {
      terms.add(randomString());
    }
    testTerms(numTerms * 100, terms.toArray(new String[terms.size()]));
  }

  private String randomString() {
    // return _TestUtil.randomSimpleString(random);
    return TestUtil.randomRealisticUnicodeString(random());
  }

  public void testBasic() throws Exception {
    CompiledAutomaton c = build(Operations.DEFAULT_DETERMINIZE_WORK_LIMIT, "fob", "foo", "goo");
    testFloor(c, "goo", "goo");
    testFloor(c, "ga", "foo");
    testFloor(c, "g", "foo");
    testFloor(c, "foc", "fob");
    testFloor(c, "foz", "foo");
    testFloor(c, "f", null);
    testFloor(c, "", null);
    testFloor(c, "aa", null);
    testFloor(c, "zzz", "goo");
  }

  // LUCENE-6367
  public void testBinaryAll() throws Exception {
    Automaton a = new Automaton();
    int state = a.createState();
    a.setAccept(state, true);
    a.addTransition(state, state, 0, 0xff);
    a.finishState();

    CompiledAutomaton ca = new CompiledAutomaton(a, null, true, Integer.MAX_VALUE, true);
    assertEquals(CompiledAutomaton.AUTOMATON_TYPE.ALL, ca.type);
  }

  // LUCENE-6367
  public void testUnicodeAll() throws Exception {
    Automaton a = new Automaton();
    int state = a.createState();
    a.setAccept(state, true);
    a.addTransition(state, state, 0, Character.MAX_CODE_POINT);
    a.finishState();

    CompiledAutomaton ca = new CompiledAutomaton(a, null, true, Integer.MAX_VALUE, false);
    assertEquals(CompiledAutomaton.AUTOMATON_TYPE.ALL, ca.type);
  }

  // LUCENE-6367
  public void testBinarySingleton() throws Exception {
    // This is just ascii so we can pretend it's binary:
    Automaton a = Automata.makeString("foobar");
    CompiledAutomaton ca = new CompiledAutomaton(a, null, true, Integer.MAX_VALUE, true);
    assertEquals(CompiledAutomaton.AUTOMATON_TYPE.SINGLE, ca.type);
  }

  // LUCENE-6367
  public void testUnicodeSingleton() throws Exception {
    Automaton a = Automata.makeString(TestUtil.randomRealisticUnicodeString(random()));
    CompiledAutomaton ca = new CompiledAutomaton(a, null, true, Integer.MAX_VALUE, false);
    assertEquals(CompiledAutomaton.AUTOMATON_TYPE.SINGLE, ca.type);
  }
}
