/*
 * Copyright (c) 2011-2019 Contributors to the Eclipse Foundation
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
 * which is available at https://www.apache.org/licenses/LICENSE-2.0.
 *
 * SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
 */

package io.vertx.core.json;

import io.vertx.core.buffer.Buffer;
import io.vertx.core.shareddata.Shareable;
import io.vertx.core.shareddata.impl.ClusterSerializable;

import java.time.Instant;
import java.util.*;
import java.util.stream.Stream;

import static io.vertx.core.json.impl.JsonUtil.*;
import static java.time.format.DateTimeFormatter.ISO_INSTANT;

/**
 * A representation of a <a href="http://json.org/">JSON</a> array in Java.
 *
 * Unlike some other languages Java does not have a native understanding of JSON. To enable JSON to be used easily
 * in Vert.x code we use this class to encapsulate the notion of a JSON array.
 *
 * The implementation adheres to the <a href="http://rfc-editor.org/rfc/rfc7493.txt">RFC-7493</a> to support Temporal
 * data types as well as binary data.
 *
 * Please see the documentation for more information.
 *
 * @author <a href="http://tfox.org">Tim Fox</a>
 */
public class JsonArray implements Iterable<Object>, ClusterSerializable, Shareable {

  private List<Object> list;

  /**
   * Create an instance from a String of JSON, this string must be a valid array otherwise an exception will be thrown.
   * <p/>
   * If you are unsure of the value, you should use instead {@link Json#decodeValue(String)} and check the result is
   * a JSON array.
   *
   * @param json the string of JSON
   */
  public JsonArray(String json) {
    if (json == null) {
      throw new NullPointerException();
    }
    fromJson(json);
    if (list == null) {
      throw new DecodeException("Invalid JSON array: " + json);
    }
  }

  /**
   * Create an empty instance
   */
  public JsonArray() {
    list = new ArrayList<>();
  }

  /**
   * Create an instance from a List. The List is not copied.
   *
   * @param list the underlying backing list
   */
  public JsonArray(List list) {
    if (list == null) {
      throw new NullPointerException();
    }
    this.list = list;
  }

  /**
   * Create an instance from a Buffer of JSON.
   *
   * @param buf the buffer of JSON.
   */
  public JsonArray(Buffer buf) {
    if (buf == null) {
      throw new NullPointerException();
    }
    fromBuffer(buf);
    if (list == null) {
      throw new DecodeException("Invalid JSON array: " + buf);
    }
  }

  /**
   * Get the String at position {@code pos} in the array,
   *
   * @param pos the position in the array
   * @return the String (or String representation), or null if a null value present
   */
  public String getString(int pos) {
    Object val = list.get(pos);

    if (val == null) {
      return null;
    }

    if (val instanceof Instant) {
      return ISO_INSTANT.format((Instant) val);
    } else if (val instanceof byte[]) {
      return BASE64_ENCODER.encodeToString((byte[]) val);
    } else if (val instanceof Enum) {
      return ((Enum) val).name();
    } else {
      return val.toString();
    }
  }

  /**
   * Get the Integer at position {@code pos} in the array,
   *
   * @param pos the position in the array
   * @return the Integer, or null if a null value present
   * @throws java.lang.ClassCastException if the value cannot be converted to Integer
   */
  public Integer getInteger(int pos) {
    Number number = (Number) list.get(pos);
    if (number == null) {
      return null;
    } else if (number instanceof Integer) {
      return (Integer) number; // Avoids unnecessary unbox/box
    } else {
      return number.intValue();
    }
  }

  /**
   * Get the Long at position {@code pos} in the array,
   *
   * @param pos the position in the array
   * @return the Long, or null if a null value present
   * @throws java.lang.ClassCastException if the value cannot be converted to Long
   */
  public Long getLong(int pos) {
    Number number = (Number) list.get(pos);
    if (number == null) {
      return null;
    } else if (number instanceof Long) {
      return (Long) number; // Avoids unnecessary unbox/box
    } else {
      return number.longValue();
    }
  }

  /**
   * Get the Double at position {@code pos} in the array,
   *
   * @param pos the position in the array
   * @return the Double, or null if a null value present
   * @throws java.lang.ClassCastException if the value cannot be converted to Double
   */
  public Double getDouble(int pos) {
    Number number = (Number) list.get(pos);
    if (number == null) {
      return null;
    } else if (number instanceof Double) {
      return (Double) number; // Avoids unnecessary unbox/box
    } else {
      return number.doubleValue();
    }
  }

  /**
   * Get the Float at position {@code pos} in the array,
   *
   * @param pos the position in the array
   * @return the Float, or null if a null value present
   * @throws java.lang.ClassCastException if the value cannot be converted to Float
   */
  public Float getFloat(int pos) {
    Number number = (Number) list.get(pos);
    if (number == null) {
      return null;
    } else if (number instanceof Float) {
      return (Float) number; // Avoids unnecessary unbox/box
    } else {
      return number.floatValue();
    }
  }

  /**
   * Get the Boolean at position {@code pos} in the array,
   *
   * @param pos the position in the array
   * @return the Boolean, or null if a null value present
   * @throws java.lang.ClassCastException if the value cannot be converted to Integer
   */
  public Boolean getBoolean(int pos) {
    return (Boolean) list.get(pos);
  }

  /**
   * Get the JsonObject at position {@code pos} in the array.
   *
   * @param pos the position in the array
   * @return the JsonObject, or null if a null value present
   * @throws java.lang.ClassCastException if the value cannot be converted to JsonObject
   */
  public JsonObject getJsonObject(int pos) {
    Object val = list.get(pos);
    if (val instanceof Map) {
      val = new JsonObject((Map) val);
    }
    return (JsonObject) val;
  }

  /**
   * Get the JsonArray at position {@code pos} in the array.
   *
   * @param pos the position in the array
   * @return the Integer, or null if a null value present
   * @throws java.lang.ClassCastException if the value cannot be converted to JsonArray
   */
  public JsonArray getJsonArray(int pos) {
    Object val = list.get(pos);
    if (val instanceof List) {
      val = new JsonArray((List) val);
    }
    return (JsonArray) val;
  }

  /**
   * Get the byte[] at position {@code pos} in the array.
   *
   * JSON itself has no notion of a binary, so this method assumes there is a String value and
   * it contains a Base64 encoded binary, which it decodes if found and returns.
   *
   * @param pos the position in the array
   * @return the byte[], or null if a null value present
   * @throws java.lang.ClassCastException       if the value cannot be converted to String
   * @throws java.lang.IllegalArgumentException if the String value is not a legal Base64 encoded value
   */
  public byte[] getBinary(int pos) {
    Object val = list.get(pos);
    // no-op
    if (val == null) {
      return null;
    }
    // no-op if value is already an byte[]
    if (val instanceof byte[]) {
      return (byte[]) val;
    }
    // assume that the value is in String format as per RFC
    String encoded = (String) val;
    // parse to proper type
    return BASE64_DECODER.decode(encoded);
  }

  /**
   * Get the Instant at position {@code pos} in the array.
   *
   * JSON itself has no notion of a temporal types, this extension complies to the RFC-7493, so this method assumes
   * there is a String value and it contains an ISO 8601 encoded date and time format such as "2017-04-03T10:25:41Z",
   * which it decodes if found and returns.
   *
   * @param pos the position in the array
   * @return the Instant, or null if a null value present
   * @throws java.lang.ClassCastException            if the value cannot be converted to String
   * @throws java.time.format.DateTimeParseException if the String value is not a legal ISO 8601 encoded value
   */
  public Instant getInstant(int pos) {
    Object val = list.get(pos);
    // no-op
    if (val == null) {
      return null;
    }
    // no-op if value is already an Instant
    if (val instanceof Instant) {
      return (Instant) val;
    }
    // assume that the value is in String format as per RFC
    String encoded = (String) val;
    // parse to proper type
    return Instant.from(ISO_INSTANT.parse(encoded));
  }

  /**
   * Get the value with the specified key, as an Object with types respecting the limitations of JSON.
   * <ul>
   *   <li>{@code Map} will be wrapped to {@code JsonObject}</li>
   *   <li>{@code List} will be wrapped to {@code JsonArray}</li>
   *   <li>{@code Instant} will be converted to {@code String}</li>
   *   <li>{@code byte[]} will be converted to {@code String}</li>
   *   <li>{@code Enum} will be converted to {@code String}</li>
   * </ul>
   *
   * @param pos the position in the array
   * @return the Integer, or null if a null value present
   */
  public Object getValue(int pos) {
    return wrapJsonValue(list.get(pos));
  }

  /**
   * Is there a null value at position pos?
   *
   * @param pos the position in the array
   * @return true if null value present, false otherwise
   */
  public boolean hasNull(int pos) {
    return list.get(pos) == null;
  }

  /**
   * Add a null value to the JSON array.
   *
   * @return a reference to this, so the API can be used fluently
   */
  public JsonArray addNull() {
    list.add(null);
    return this;
  }

  /**
   * Add an Object to the JSON array.
   *
   * @param value the value
   * @return a reference to this, so the API can be used fluently
   */
  public JsonArray add(Object value) {
    list.add(value);
    return this;
  }

  /**
   * Add an Object to the JSON array at given position {@code pos}.
   *
   * @param pos the position
   * @param value the value
   * @return a reference to this, so the API can be used fluently
   */
  public JsonArray add(int pos, Object value) {
    list.add(pos, value);
    return this;
  }

  /**
   * Appends all of the elements in the specified array to the end of this JSON array.
   *
   * @param array the array
   * @return a reference to this, so the API can be used fluently
   */
  public JsonArray addAll(JsonArray array) {
    list.addAll(array.list);
    return this;
  }

  /**
   * Set a null value to the JSON array at position {@code pos}.
   *
   * @return a reference to this, so the API can be used fluently
   */
  public JsonArray setNull(int pos) {
    list.set(pos, null);
    return this;
  }

  /**
   * Set an Object to the JSON array at position {@code pos}.
   *
   * @param pos   position in the array
   * @param value the value
   * @return a reference to this, so the API can be used fluently
   */
  public JsonArray set(int pos, Object value) {
    list.set(pos, value);
    return this;
  }

  /**
   * Does the JSON array contain the specified value? This method will scan the entire array until it finds a value
   * or reaches the end.
   *
   * @param value the value
   * @return true if it contains the value, false if not
   */
  public boolean contains(Object value) {
    return list.contains(value);
  }

  /**
   * Remove the specified value from the JSON array. This method will scan the entire array until it finds a value
   * or reaches the end.
   *
   * @param value the value to remove
   * @return true if it removed it, false if not found
   */
  public boolean remove(Object value) {
    final Object wrappedValue = wrapJsonValue(value);
    for (int i = 0; i < list.size(); i++) {
      // perform comparision on wrapped types
      final Object otherWrapperValue = getValue(i);
      if (wrappedValue == null) {
        if (otherWrapperValue == null) {
          list.remove(i);
          return true;
        }
      } else {
        if (wrappedValue.equals(otherWrapperValue)) {
          list.remove(i);
          return true;
        }
      }
    }
    return false;
  }

  /**
   * Remove the value at the specified position in the JSON array.
   *
   * @param pos the position to remove the value at
   * @return the removed value if removed, null otherwise. If the value is a Map, a {@link JsonObject} is built from
   * this Map and returned. It the value is a List, a {@link JsonArray} is built form this List and returned.
   */
  public Object remove(int pos) {
    return wrapJsonValue(list.remove(pos));
  }

  /**
   * Get the number of values in this JSON array
   *
   * @return the number of items
   */
  public int size() {
    return list.size();
  }

  /**
   * Are there zero items in this JSON array?
   *
   * @return true if zero, false otherwise
   */
  public boolean isEmpty() {
    return list.isEmpty();
  }

  /**
   * Get the unerlying List
   *
   * @return the underlying List
   */
  public List getList() {
    return list;
  }

  /**
   * Remove all entries from the JSON array
   *
   * @return a reference to this, so the API can be used fluently
   */
  public JsonArray clear() {
    list.clear();
    return this;
  }

  /**
   * Get an Iterator over the values in the JSON array
   *
   * @return an iterator
   */
  @Override
  public Iterator<Object> iterator() {
    return new Iter(list.iterator());
  }

  /**
   * Encode the JSON array to a string
   *
   * @return the string encoding
   */
  public String encode() {
    return Json.CODEC.toString(this, false);
  }

  /**
   * Encode this JSON object as buffer.
   *
   * @return the buffer encoding.
   */
  public Buffer toBuffer() {
    return Json.CODEC.toBuffer(this, false);
  }

  /**
   * Encode the JSON array prettily as a string
   *
   * @return the string encoding
   */
  public String encodePrettily() {
    return Json.CODEC.toString(this, true);
  }

  /**
   * Make a copy of the JSON array
   *
   * @return a copy
   */
  @Override
  public JsonArray copy() {
    List<Object> copiedList = new ArrayList<>(list.size());
    for (Object val : list) {
      copiedList.add(checkAndCopy(val));
    }
    return new JsonArray(copiedList);
  }

  /**
   * Get a Stream over the entries in the JSON array
   *
   * @return a Stream
   */
  public Stream<Object> stream() {
    return JsonObject.asStream(iterator());
  }

  @Override
  public String toString() {
    return encode();
  }

  @Override
  public boolean equals(Object o) {
    // null check
    if (o == null)
      return false;
    // self check
    if (this == o)
      return true;
    // type check and cast
    if (getClass() != o.getClass())
      return false;

    JsonArray other = (JsonArray) o;
    // size check
    if (this.size() != other.size())
      return false;
    // value comparison
    for (int i = 0; i < this.size(); i++) {
      Object thisValue = this.getValue(i);
      Object otherValue = other.getValue(i);
      // identity check
      if (thisValue == otherValue) {
        continue;
      }
      // special case for numbers
      if (thisValue instanceof Number && otherValue instanceof Number && thisValue.getClass() != otherValue.getClass()) {
        Number n1 = (Number) thisValue;
        Number n2 = (Number) otherValue;
        // floating point values
        if (thisValue instanceof Float || thisValue instanceof Double || otherValue instanceof Float || otherValue instanceof Double) {
          // compare as floating point double
          if (n1.doubleValue() == n2.doubleValue()) {
            // same value check the next entry
            continue;
          }
        }
        if (thisValue instanceof Integer || thisValue instanceof Long || otherValue instanceof Integer || otherValue instanceof Long) {
          // compare as integer long
          if (n1.longValue() == n2.longValue()) {
            // same value check the next entry
            continue;
          }
        }
      }
      // special case for char sequences
      if (thisValue instanceof CharSequence && otherValue instanceof CharSequence && thisValue.getClass() != otherValue.getClass()) {
        CharSequence s1 = (CharSequence) thisValue;
        CharSequence s2 = (CharSequence) otherValue;

        if (Objects.equals(s1.toString(), s2.toString())) {
          // same value check the next entry
          continue;
        }
      }
      // fallback to standard object equals checks
      if (!Objects.equals(thisValue, otherValue)) {
        return false;
      }
    }
    // all checks passed
    return true;
  }

  @Override
  public int hashCode() {
    return list.hashCode();
  }

  @Override
  public void writeToBuffer(Buffer buffer) {
    String encoded = encode();
    byte[] bytes = encoded.getBytes();
    buffer.appendInt(bytes.length);
    buffer.appendBytes(bytes);
  }

  @Override
  public int readFromBuffer(int pos, Buffer buffer) {
    int length = buffer.getInt(pos);
    int start = pos + 4;
    String encoded = buffer.getString(start, start + length);
    fromJson(encoded);
    return pos + length + 4;
  }

  private void fromJson(String json) {
    list = Json.CODEC.fromString(json, List.class);
  }

  private void fromBuffer(Buffer buf) {
    list = Json.CODEC.fromBuffer(buf, List.class);
  }

  private static class Iter implements Iterator<Object> {

    final Iterator<Object> listIter;

    Iter(Iterator<Object> listIter) {
      this.listIter = listIter;
    }

    @Override
    public boolean hasNext() {
      return listIter.hasNext();
    }

    @Override
    public Object next() {
      return wrapJsonValue(listIter.next());
    }

    @Override
    public void remove() {
      listIter.remove();
    }
  }
}
