import { v4 as uuid } from "uuid";
import { EntitySchema } from "../schema/entity-schema";
import { DatabaseField } from "../database-field.decorator";
import {
  getWarningLevelColor,
  WarningLevel,
} from "../../../child-dev-project/warning-level";
import { IconName } from "@fortawesome/fontawesome-svg-core";
import { UpdateMetadata } from "./update-metadata";
import { EntityBlockConfig } from "../../basic-datatypes/entity/entity-block/entity-block-config";
import { Logging } from "../../logging/logging.service";

/**
 * This represents a static class of type <T>.
 * It can be used for passing a class from which new objects should be created.
 * It can also be used to check the ENTITY_TYPE of a class
 * For example usage check the {@link EntityMapperService}.
 */
export type EntityConstructor<T extends Entity = Entity> = (new (
  id?: string,
) => T) &
  typeof Entity;

/**
 * "Entity" is a base class for all domain model classes.
 * It implements the basic general properties and methods that are required for all Entity types
 * e.g. supporting the Entity Schema system or basic database logic.
 *
 * Entity classes do not deal with database actions, use {@link EntityMapperService} with its find/save/delete functions.
 *
 * Do not use the Entity class directly. Instead, implement your own Entity types, writing classes that extend "Entity".
 * A How-To Guide on how to implement your own types is available:
 * - [How to Create a new Entity Type]{@link /additional-documentation/how-to-guides/create-a-new-entity-type.html}
 */
export class Entity {
  /**
   * The entity's type.
   * In classes extending Entity this is usually overridden by the class annotation `@DatabaseEntity('NewEntity')`.
   * The type needs to be used as routing path in lower case. The routing path can be defined in the configuration file.
   */
  static ENTITY_TYPE = "Entity";

  /**
   * The database where these entities are stored.
   */
  static DATABASE = "app";

  /**
   * EntitySchema defining property transformations from/to the database.
   * This is auto-generated from the property annotations `@DatabaseField()`.
   *
   * see {@link /additional-documentation/how-to-guides/create-a-new-entity-type.html}
   */
  static schema: EntitySchema;

  /**
   * True if this type's schema has been customized dynamically from the config.
   */
  static _isCustomizedType?: boolean; // todo should be private or renamed to "isCustomizedType"

  /**
   * Defining which attribute values of an entity should be shown in the `.toString()` method.
   *
   * The default is the ID of the entity (`entityId`).
   * This can be overwritten in subclasses or through the config.
   */
  static toStringAttributes = ["entityId"];

  /**
   * Defining which attributes will be displayed in a tooltip on hover when the record is displayed as an entity-block.
   */
  static toBlockDetailsAttributes?: EntityBlockConfig;

  /**
   * human-readable name/label of the entity in the UI
   */
  static label: string;

  /**
   * human-readable label for uses of plural of the entity in the UI
   */
  static get labelPlural(): string {
    return this._labelPlural ?? this.label;
  }

  static set labelPlural(value: string) {
    this._labelPlural = value;
  }

  private static _labelPlural: string;

  /**
   * Returns a human-readable string representation of the entity *type*
   * (not the individual record).
   */
  static toString(plural: boolean = false): string {
    const result = plural ? this.labelPlural : this.label;
    return result ?? this.ENTITY_TYPE;
  }

  /**
   * icon id used for this entity
   */
  static icon: IconName;

  /**
   * color used for to highlight this entity type across the app
   */
  static color: string;

  /**
   * Base route of the entity (list/details) view for this entity type.
   */
  static get route(): string {
    let route = this._route ?? this.ENTITY_TYPE.toLowerCase();
    if (!route.startsWith("/")) {
      route = "/" + route;
    }
    return route;
  }

  static set route(value: string) {
    this._route = value;
  }

  private static _route: string;

  /**
   * Extract the ENTITY_TYPE from an id.
   * @param id An entity's id including prefix.
   */
  static extractTypeFromId(id: string): string {
    const split = id.indexOf(":");
    return id.substring(0, split);
  }

  /**
   * Extract entityId without prefix.
   * @param id An entity's id including prefix.
   */
  static extractEntityIdFromId(id: string): string {
    let type: string = undefined;
    try {
      const split = id.indexOf(":");
      type = id.substring(split + 1);
    } catch (e) {
      Logging.debug("Error extracting entityId from id", id, e);
    }
    return type;
  }

  /**
   * Create a prefixed id by adding the type prefix if it isn't already part of the given id.
   * @param type The type prefix to be added.
   * @param id The id to be extended with a prefix.
   */
  static createPrefixedId(type: string, id: string): string {
    id = String(id);
    const prefix = type + ":";
    if (!id.startsWith(prefix)) {
      return prefix + id;
    } else {
      return id;
    }
  }

  /**
   * whether this entity type can contain "personally identifiable information" (PII)
   * and therefore should follow strict data protection requirements
   * and offer a function to anonymize records.
   */
  static hasPII: boolean = false;

  /**
   * Internal database id.
   * This is usually combined from the ENTITY_TYPE as a prefix with the entityId field `EntityType:entityId`
   * @example "Entity:123"
   */
  @DatabaseField({ anonymize: "retain" }) private _id: string;

  /** internal database doc revision, used to detect conflicts by PouchDB/CouchDB */
  @DatabaseField({ anonymize: "retain" }) _rev: string;

  @DatabaseField({
    anonymize: "retain",
  })
  created: UpdateMetadata;

  @DatabaseField({
    anonymize: "retain",
  })
  updated: UpdateMetadata;

  @DatabaseField({ anonymize: "retain" })
  inactive: boolean;

  /**
   * Whether this entity has been anonymized and therefore cannot be re-activated.
   */
  @DatabaseField({ anonymize: "retain" })
  anonymized: boolean;

  /** whether this entity object is newly created and not yet saved to database */
  get isNew(): boolean {
    return !this._rev;
  }

  /** actual id without prefix */
  private get entityId(): string {
    return Entity.extractEntityIdFromId(this._id);
  }

  /**
   * Set id without prefix.
   * @param newEntityId The new id without prefix.
   */
  private set entityId(newEntityId: string) {
    this._id = Entity.createPrefixedId(this.getType(), newEntityId);
  }

  /**
   * Check, if this entity is considered active or archived.
   *
   * This is taken from the property "inactive".
   * If the property doesn't exist, the default is `true`.
   *
   * Some subclasses overwrite this functionality, but this logic is considered deprecated (!) now
   * and implementations have to make sure that "inactive" property takes precedence!
   */
  get isActive(): boolean {
    if (this.inactive !== undefined) {
      return !this.inactive;
    }
    if (this["active"] !== undefined) {
      return this["active"];
    }
    return true;
  }

  /**
   * If existing entities with `isActive: false` exist, then these values are assigned to the property "active".
   * @param isActive
   */
  set isActive(isActive: boolean) {
    this["active"] = isActive;
    this.inactive = !isActive;
  }

  /**
   * Creates an entity object with the given id. This id is final and won't be changeable after this object has been
   * created.
   *
   * @param id a unique id for this entity; if no id is passed a uuid is generated automatically
   */
  constructor(id: string = uuid()) {
    this.entityId = id;
  }

  /**
   * Get the class (Entity or the actual subclass of the instance) to call static methods on the correct class considering inheritance
   */
  getConstructor(): EntityConstructor<this> {
    return this.constructor as EntityConstructor<this>;
  }

  /**
   * Get the entity schema of this class
   */
  getSchema(): EntitySchema {
    return this.getConstructor().schema;
  }

  /**
   * Returns the id of this entity.
   *
   * Note that an id is final and can't be changed after the object has been instantiated, hence there is no
   * <code>setId()</code> method.
   *
   * @returns {string} the unique id of this entity
   */
  public getId(withoutPrefix = false): string {
    return withoutPrefix ? this.entityId : this._id;
  }

  /**
   * Returns the type which is used to categorize this entity in the database.
   *
   * <b>Important: Do not overwrite this method! Types are handled internally.</b>
   *
   * @returns {string} the entity's type (which is the class name).
   */
  public getType(): string {
    return this.getConstructor().ENTITY_TYPE;
  }

  /**
   * Returns a string representation or summary of the instance.
   * This can be configured with the static `toStringAttributes` for each subclass.
   *
   * @returns {string} the instance's string representation.
   */
  public toString(): string {
    if (
      this.anonymized &&
      this.getConstructor().toStringAttributes.every(
        (attr) => this[attr] === undefined,
      )
    ) {
      return $localize`:Entity.toString fallback for anonymized record:[anonymized ${
        this.getConstructor().label
      }]`;
    }

    return this.getConstructor()
      .toStringAttributes.map((attr) => {
        let value = this[attr];
        if (value?.label) {
          value = value.label;
        }
        if (value instanceof Date) {
          value = value.toLocaleDateString();
        }
        return value;
      })
      .join(" ");
  }

  /**
   * Used by some generic UI components to set the color for the entity instance.
   * Override this method as needed.
   */
  public getColor(): string {
    return getWarningLevelColor(this.getWarningLevel());
  }

  /**
   * Override getWarningLevel() to define when the entity is in a critical condition and should be color-coded
   * and highlighted in generic components of the UI.
   */
  public getWarningLevel(): WarningLevel {
    return WarningLevel.NONE;
  }

  /**
   * Shallow copy of the entity.
   * The resulting entity will be of the same type as this
   * (taking into account subclassing)
   *
   * @param newId if true, a new entityId will be generated; if a string, that value is used as new entityId
   */
  public copy(newId: string | boolean = false): this {
    const other = new (this.getConstructor())(this._id);
    Object.assign(other, this);

    if (newId) {
      other.entityId = typeof newId === "string" ? newId : uuid();
      delete other._rev;
      delete other.created;
      delete other.updated;
    }

    return other;
  }

  /**
   * Checks if the entity is valid and if the check fails, throws an error explaining the failed check.
   */
  assertValid(): void {
    return;
  }
}