package com.box.sdk;

import com.eclipsesource.json.Json;
import com.eclipsesource.json.JsonArray;
import com.eclipsesource.json.JsonObject;
import com.eclipsesource.json.JsonValue;
import java.net.URL;
import java.util.Iterator;

/**
 * Collections contain information about the items contained inside of them, including files and
 * folders. The only collection available currently is a “Favorites” collection.
 *
 * <p>Unless otherwise noted, the methods in this class can throw an unchecked {@link
 * BoxAPIException} (unchecked meaning that the compiler won't force you to handle it) if an error
 * occurs. If you wish to implement custom error handling for errors related to the Box REST API,
 * you should capture this exception explicitly.
 */
@BoxResourceType("collection")
public class BoxCollection extends BoxResource implements Iterable<BoxItem.Info> {

  /** Get Collections URL Template. */
  public static final URLTemplate GET_COLLECTIONS_URL_TEMPLATE = new URLTemplate("collections/");
  /** Get Collection Items URL Template. */
  public static final URLTemplate GET_COLLECTION_ITEMS_URL =
      new URLTemplate("collections/%s/items/");

  /**
   * Constructs a BoxCollection for a collection with a given ID.
   *
   * @param api the API connection to be used by the collection.
   * @param id the ID of the collection.
   */
  public BoxCollection(BoxAPIConnection api, String id) {
    super(api, id);
  }

  /**
   * Gets an iterable of all the collections for the given user.
   *
   * @param api the API connection to be used when retrieving the collections.
   * @return an iterable containing info about all the collections.
   */
  public static Iterable<BoxCollection.Info> getAllCollections(final BoxAPIConnection api) {
    return () -> {
      URL url = GET_COLLECTIONS_URL_TEMPLATE.build(api.getBaseURL());
      return new BoxCollectionIterator(api, url);
    };
  }

  /**
   * Returns an iterable containing the items in this collection. Iterating over the iterable
   * returned by this method is equivalent to iterating over this BoxCollection directly.
   *
   * @return an iterable containing the items in this collection.
   */
  public Iterable<BoxItem.Info> getItems() {
    return this;
  }

  /**
   * Returns an iterable containing the items in this collection and specifies which attributes to
   * include in the response.
   *
   * @param fields the fields to retrieve.
   * @return an iterable containing the items in this collection.
   */
  public Iterable<BoxItem.Info> getItems(final String... fields) {
    return () -> {
      String queryString = new QueryStringBuilder().appendParam("fields", fields).toString();
      URL url =
          GET_COLLECTION_ITEMS_URL.buildWithQuery(getAPI().getBaseURL(), queryString, getID());
      return new BoxItemIterator(getAPI(), url);
    };
  }

  /**
   * Retrieves a specific range of items in this collection.
   *
   * @param offset the index of the first item to retrieve.
   * @param limit the maximum number of items to retrieve after the offset.
   * @param fields the fields to retrieve.
   * @return a partial collection containing the specified range of items.
   */
  public PartialCollection<BoxItem.Info> getItemsRange(long offset, long limit, String... fields) {
    QueryStringBuilder builder =
        new QueryStringBuilder().appendParam("offset", offset).appendParam("limit", limit);

    if (fields.length > 0) {
      builder.appendParam("fields", fields);
    }

    URL url =
        GET_COLLECTION_ITEMS_URL.buildWithQuery(getAPI().getBaseURL(), builder.toString(), getID());
    BoxJSONRequest request = new BoxJSONRequest(this.getAPI(), url, "GET");
    try (BoxJSONResponse response = request.send()) {
      JsonObject responseJSON = Json.parse(response.getJSON()).asObject();

      String totalCountString = responseJSON.get("total_count").toString();
      long fullSize = Double.valueOf(totalCountString).longValue();
      PartialCollection<BoxItem.Info> items = new PartialCollection<>(offset, limit, fullSize);
      JsonArray entries = responseJSON.get("entries").asArray();
      for (JsonValue entry : entries) {
        BoxItem.Info entryInfo =
            (BoxItem.Info) BoxResource.parseInfo(this.getAPI(), entry.asObject());
        if (entryInfo != null) {
          items.add(entryInfo);
        }
      }
      return items;
    }
  }

  /**
   * Returns an iterator over the items in this collection.
   *
   * @return an iterator over the items in this collection.
   */
  @Override
  public Iterator<BoxItem.Info> iterator() {
    URL url =
        GET_COLLECTION_ITEMS_URL.build(this.getAPI().getBaseURL(), BoxCollection.this.getID());
    return new BoxItemIterator(BoxCollection.this.getAPI(), url);
  }

  /** Contains information about a BoxCollection. */
  public class Info extends BoxResource.Info {
    private String collectionType;
    private String name;

    /** Constructs an empty Info object. */
    public Info() {
      super();
    }

    /**
     * Constructs an Info object by parsing information from a JSON string.
     *
     * @param json the JSON string to parse.
     */
    public Info(String json) {
      super(json);
    }

    /**
     * Constructs an Info object using an already parsed JSON object.
     *
     * @param jsonObject the parsed JSON object.
     */
    Info(JsonObject jsonObject) {
      super(jsonObject);
    }

    /**
     * Gets the type of the collection.
     *
     * @return the type of the collection.
     */
    public String getCollectionType() {
      return this.collectionType;
    }

    /**
     * Gets the name of the collection.
     *
     * @return the name of the collection.
     */
    public String getName() {
      return this.name;
    }

    @Override
    public BoxCollection getResource() {
      return BoxCollection.this;
    }

    @Override
    protected void parseJSONMember(JsonObject.Member member) {
      super.parseJSONMember(member);

      String memberName = member.getName();
      JsonValue value = member.getValue();
      if (memberName.equals("collection_type")) {
        this.collectionType = value.asString();
      } else if (memberName.equals("name")) {
        this.name = value.asString();
      }
    }
  }
}