package com.box.sdk;

import com.eclipsesource.json.JsonArray;
import com.eclipsesource.json.JsonObject;
import com.eclipsesource.json.JsonValue;
import java.text.ParseException;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Optional;

/**
 * The Metadata class represents one type instance of Box metadata.
 *
 * <p>Learn more about Box metadata: https://developers.box.com/metadata-api/
 */
public class Metadata {

  /** Specifies the name of the default "properties" metadata template. */
  public static final String DEFAULT_METADATA_TYPE = "properties";

  /** Specifies the "global" metadata scope. */
  public static final String GLOBAL_METADATA_SCOPE = "global";

  /** Specifies the "enterprise" metadata scope. */
  public static final String ENTERPRISE_METADATA_SCOPE = "enterprise";

  /** Specifies the classification template key. */
  public static final String CLASSIFICATION_TEMPLATE_KEY = "securityClassification-6VMVochwUWo";

  /** Classification key path. */
  public static final String CLASSIFICATION_KEY = "/Box__Security__Classification__Key";

  /** The default limit of entries per response. */
  public static final int DEFAULT_LIMIT = 100;

  /** URL template for all metadata associated with item. */
  public static final URLTemplate GET_ALL_METADATA_URL_TEMPLATE = new URLTemplate("/metadata");

  /** Values contained by the metadata object. */
  private final JsonObject values;

  /** Operations to be applied to the metadata object. */
  private JsonArray operations = new JsonArray();

  /** Creates an empty metadata. */
  public Metadata() {
    this.values = new JsonObject();
  }

  /**
   * Creates a new metadata.
   *
   * @param values the initial metadata values.
   */
  public Metadata(JsonObject values) {
    this.values = values;
  }

  /**
   * Creates a copy of another metadata.
   *
   * @param other the other metadata object to copy.
   */
  public Metadata(Metadata other) {
    this.values = new JsonObject(other.values);
  }

  /**
   * Creates a new metadata with the specified scope and template.
   *
   * @param scope the scope of the metadata.
   * @param template the template of the metadata.
   */
  public Metadata(String scope, String template) {
    this.values = new JsonObject().add("$scope", scope).add("$template", template);
  }

  /**
   * Used to retrieve all metadata associated with the item.
   *
   * @param item item to get metadata for.
   * @param fields the optional fields to retrieve.
   * @return An iterable of metadata instances associated with the item.
   */
  public static Iterable<Metadata> getAllMetadata(BoxItem item, String... fields) {
    QueryStringBuilder builder = new QueryStringBuilder();
    if (fields.length > 0) {
      builder.appendParam("fields", fields);
    }
    return new BoxResourceIterable<Metadata>(
        item.getAPI(),
        GET_ALL_METADATA_URL_TEMPLATE.buildWithQuery(
            item.getItemURL().toString(), builder.toString()),
        DEFAULT_LIMIT) {

      @Override
      protected Metadata factory(JsonObject jsonObject) {
        return new Metadata(jsonObject);
      }
    };
  }

  static String scopeBasedOnType(String typeName) {
    String scope;
    if (typeName.equals(DEFAULT_METADATA_TYPE)) {
      scope = GLOBAL_METADATA_SCOPE;
    } else {
      scope = ENTERPRISE_METADATA_SCOPE;
    }
    return scope;
  }

  /**
   * Returns the 36 character UUID to identify the metadata object.
   *
   * @return the metadata ID.
   */
  public String getID() {
    return getStringOrNull("/$id");
  }

  /**
   * Returns the metadata type.
   *
   * @return the metadata type.
   */
  public String getTypeName() {
    return getStringOrNull("/$type");
  }

  /**
   * Returns the parent object ID (typically the file ID).
   *
   * @return the parent object ID.
   */
  public String getParentID() {
    return getStringOrNull("/$parent");
  }

  /**
   * Returns the scope. Can throw {@link NullPointerException} is value if not present.
   *
   * @return the scope.
   */
  public String getScope() {
    return getStringOrNull("/$scope");
  }

  /**
   * Returns the template name. Can throw {@link NullPointerException} is value if not present.
   *
   * @return the template name.
   */
  public String getTemplateName() {
    return getStringOrNull("/$template");
  }

  /**
   * Adds a new metadata value.
   *
   * @param path the path that designates the key. Must be prefixed with a "/".
   * @param value the value.
   * @return this metadata object.
   */
  public Metadata add(String path, String value) {
    this.values.add(this.pathToProperty(path), value);
    this.addOp("add", path, value);
    return this;
  }

  /**
   * Adds a new metadata value.
   *
   * @param path the path that designates the key. Must be prefixed with a "/".
   * @param value the value.
   * @return this metadata object.
   */
  public Metadata add(String path, double value) {
    this.values.add(this.pathToProperty(path), value);
    this.addOp("add", path, value);
    return this;
  }

  /**
   * Adds a new metadata value of array type.
   *
   * @param path the path to the field.
   * @param values the collection of values.
   * @return the metadata object for chaining.
   */
  public Metadata add(String path, List<String> values) {
    JsonArray arr = new JsonArray();
    for (String value : values) {
      arr.add(value);
    }
    this.values.add(this.pathToProperty(path), arr);
    this.addOp("add", path, arr);
    return this;
  }

  /**
   * Replaces an existing metadata value.
   *
   * @param path the path that designates the key. Must be prefixed with a "/".
   * @param value the value.
   * @return this metadata object.
   */
  public Metadata replace(String path, String value) {
    this.values.set(this.pathToProperty(path), value);
    this.addOp("replace", path, value);
    return this;
  }

  /**
   * Replaces an existing metadata value.
   *
   * @param path the path that designates the key. Must be prefixed with a "/".
   * @param value the value.
   * @return this metadata object.
   */
  public Metadata replace(String path, float value) {
    this.values.set(this.pathToProperty(path), value);
    this.addOp("replace", path, value);
    return this;
  }

  /**
   * Replaces an existing metadata value.
   *
   * @param path the path that designates the key. Must be prefixed with a "/".
   * @param value the value.
   * @return this metadata object.
   */
  public Metadata replace(String path, double value) {
    this.values.set(this.pathToProperty(path), value);
    this.addOp("replace", path, value);
    return this;
  }

  /**
   * Replaces an existing metadata value of array type.
   *
   * @param path the path that designates the key. Must be prefixed with a "/".
   * @param values the collection of values.
   * @return the metadata object.
   */
  public Metadata replace(String path, List<String> values) {
    JsonArray arr = new JsonArray();
    for (String value : values) {
      arr.add(value);
    }
    this.values.add(this.pathToProperty(path), arr);
    this.addOp("replace", path, arr);
    return this;
  }

  /**
   * Removes an existing metadata value.
   *
   * @param path the path that designates the key. Must be prefixed with a "/".
   * @return this metadata object.
   */
  public Metadata remove(String path) {
    this.values.remove(this.pathToProperty(path));
    this.addOp("remove", path, (String) null);
    return this;
  }

  /**
   * Tests that a property has the expected value.
   *
   * @param path the path that designates the key. Must be prefixed with a "/".
   * @param value the expected value.
   * @return this metadata object.
   */
  public Metadata test(String path, String value) {
    this.addOp("test", path, value);
    return this;
  }

  /**
   * Tests that a list of properties has the expected value. The values passed in will have to be an
   * exact match with no extra elements.
   *
   * @param path the path that designates the key. Must be prefixed with a "/".
   * @param values the list of expected values.
   * @return this metadata object.
   */
  public Metadata test(String path, List<String> values) {
    JsonArray arr = new JsonArray();
    for (String value : values) {
      arr.add(value);
    }
    this.addOp("test", path, arr);
    return this;
  }

  /**
   * Returns a value, regardless of type.
   *
   * @param path the path that designates the key. Must be prefixed with a "/".
   * @return the metadata property value as an indeterminate JSON type.
   */
  public JsonValue getValue(String path) {
    return this.values.get(this.pathToProperty(path));
  }

  /**
   * Get a value from a string or enum metadata field. Can throw {@link NullPointerException} is
   * value if not present.
   *
   * @param path the key path in the metadata object. Must be prefixed with a "/".
   * @return the metadata value as a string.
   */
  public String getString(String path) {
    return this.getValue(path).asString();
  }

  /**
   * Get a value from a double metadata field. Can throw {@link NullPointerException} is value if
   * not present.
   *
   * @param path the key path in the metadata object. Must be prefixed with a "/".
   * @return the metadata value as a floating point number.
   */
  public double getDouble(String path) {
    return this.getValue(path).asDouble();
  }

  /**
   * Get a value from a date metadata field. Can throw {@link NullPointerException} is value if not
   * present.
   *
   * @param path the key path in the metadata object. Must be prefixed with a "/".
   * @return the metadata value as a Date.
   * @throws ParseException when the value cannot be parsed as a valid date
   */
  public Date getDate(String path) throws ParseException {
    return BoxDateFormat.parse(this.getValue(path).asString());
  }

  /**
   * Get a value from a multiselect metadata field.
   *
   * @param path the key path in the metadata object. Must be prefixed with a "/".
   * @return the list of values set in the field.
   */
  public List<String> getMultiSelect(String path) {
    List<String> values = new ArrayList<>();
    for (JsonValue val : this.getValue(path).asArray()) {
      values.add(val.asString());
    }

    return values;
  }

  /**
   * Returns a list of metadata property paths.
   *
   * @return the list of metdata property paths.
   */
  public List<String> getPropertyPaths() {
    List<String> result = new ArrayList<>();

    for (String property : this.values.names()) {
      if (!property.startsWith("$")) {
        result.add(this.propertyToPath(property));
      }
    }

    return result;
  }

  /**
   * Returns the JSON patch string with all operations.
   *
   * @return the JSON patch string.
   */
  public String getPatch() {
    if (this.operations == null) {
      return "[]";
    }
    return this.operations.toString();
  }

  /**
   * Returns an array of operations on metadata.
   *
   * @return a JSON array of operations.
   */
  public JsonArray getOperations() {
    return this.operations;
  }

  /**
   * Returns the JSON representation of this metadata.
   *
   * @return the JSON representation of this metadata.
   */
  @Override
  public String toString() {
    return this.values.toString();
  }

  /**
   * Converts a JSON patch path to a JSON property name. Currently the metadata API only supports
   * flat maps.
   *
   * @param path the path that designates the key. Must be prefixed with a "/".
   * @return the JSON property name.
   */
  private String pathToProperty(String path) {
    if (path == null || !path.startsWith("/")) {
      throw new IllegalArgumentException("Path must be prefixed with a \"/\".");
    }
    return path.substring(1);
  }

  /**
   * Converts a JSON property name to a JSON patch path.
   *
   * @param property the JSON property name.
   * @return the path that designates the key.
   */
  private String propertyToPath(String property) {
    if (property == null) {
      throw new IllegalArgumentException("Property must not be null.");
    }
    return "/" + property;
  }

  /**
   * Adds a patch operation.
   *
   * @param op the operation type. Must be add, replace, remove, or test.
   * @param path the path that designates the key. Must be prefixed with a "/".
   * @param value the value to be set.
   */
  private void addOp(String op, String path, String value) {
    if (this.operations == null) {
      this.operations = new JsonArray();
    }

    this.operations.add(new JsonObject().add("op", op).add("path", path).add("value", value));
  }

  /**
   * Adds a patch operation.
   *
   * @param op the operation type. Must be add, replace, remove, or test.
   * @param path the path that designates the key. Must be prefixed with a "/".
   * @param value the value to be set.
   */
  private void addOp(String op, String path, double value) {
    if (this.operations == null) {
      this.operations = new JsonArray();
    }

    this.operations.add(new JsonObject().add("op", op).add("path", path).add("value", value));
  }

  /**
   * Adds a new patch operation for array values.
   *
   * @param op the operation type. Must be add, replace, remove, or test.
   * @param path the path that designates the key. Must be prefixed with a "/".
   * @param values the array of values to be set.
   */
  private void addOp(String op, String path, JsonArray values) {

    if (this.operations == null) {
      this.operations = new JsonArray();
    }

    this.operations.add(new JsonObject().add("op", op).add("path", path).add("value", values));
  }

  private String getStringOrNull(String path) {
    return Optional.ofNullable(this.getValue(path)).map(JsonValue::asString).orElse(null);
  }
}