import { dedupeMixin } from '@lion/core';
import { ObserverMixin } from '@lion/core/src/ObserverMixin.js';
import { Unparseable } from '@lion/validate';

/**
 * @desc `InteractionStateMixin` adds meta information about touched and dirty states, that can
 * be read by other form components (ing-uic-input-error for instance, uses the touched state
 * to determine whether an error message needs to be shown).
 * Interaction states will be set when a user:
 * - leaves a form field(blur) -> 'touched' will be set to true. 'prefilled' when a
 *   field is left non-empty
 * - on keyup (actually, on the model-value-changed event) -> 'dirty' will be set to true
 * @param {HTMLElement} superclass
 */
export const InteractionStateMixin = dedupeMixin(
  superclass =>
    // eslint-disable-next-line no-unused-vars, no-shadow
    class InteractionStateMixin extends ObserverMixin(superclass) {
      static get properties() {
        return {
          /**
           * True when user has focused and left(blurred) the field.
           */
          touched: {
            type: Boolean,
            reflect: true,
          },

          /**
           * True when user has typed in something in the input field.
           */
          dirty: {
            type: Boolean,
            reflect: true,
          },

          /**
           * True when user has left non-empty field or input is prefilled.
           * The name must be seen from the point of view of the input field:
           * once the user enters the input field, the value is non-empty.
           */
          prefilled: {
            type: Boolean,
          },
        };
      }

      static get syncObservers() {
        return {
          ...super.syncObservers,
          _onTouchedChanged: ['touched'],
          _onDirtyChanged: ['dirty'],
        };
      }

      static _isPrefilled(modelValue) {
        let value = modelValue;
        if (modelValue instanceof Unparseable) {
          value = modelValue.viewValue;
        }
        // Checks for empty platform types: Objects, Arrays, Dates
        if (typeof value === 'object' && value !== null && !(value instanceof Date)) {
          return !!Object.keys(value).length;
        }
        // eslint-disable-next-line no-mixed-operators
        // Checks for empty platform types: Numbers, Booleans
        const isNumberValue = typeof value === 'number' && (value === 0 || Number.isNaN(value));
        const isBooleanValue = typeof value === 'boolean' && value === false;

        return !!value || isNumberValue || isBooleanValue;
      }

      constructor() {
        super();
        this.touched = false;
        this.dirty = false;
        this.prefilled = false;
        this._leaveEvent = 'blur';
        this._valueChangedEvent = 'model-value-changed';

        this._iStateOnLeave = this._iStateOnLeave.bind(this);
        this._iStateOnValueChange = this._iStateOnValueChange.bind(this);
      }

      /**
       * Register event handlers and validate prefilled inputs
       */
      connectedCallback() {
        if (super.connectedCallback) {
          super.connectedCallback();
        }
        this.addEventListener(this._leaveEvent, this._iStateOnLeave);
        this.addEventListener(this._valueChangedEvent, this._iStateOnValueChange);
        this.initInteractionState();
      }

      disconnectedCallback() {
        if (super.disconnectedCallback) {
          super.disconnectedCallback();
        }
        this.removeEventListener(this._leaveEvent, this._iStateOnLeave);
        this.removeEventListener(this._valueChangedEvent, this._iStateOnValueChange);
      }

      updated(changedProperties) {
        super.updated(changedProperties);
        // classes are added only for backward compatibility - they are deprecated
        if (changedProperties.has('touched')) {
          this.classList[this.touched ? 'add' : 'remove']('state-touched');
        }
        if (changedProperties.has('dirty')) {
          this.classList[this.dirty ? 'add' : 'remove']('state-dirty');
        }
      }

      /**
       * Evaluations performed on connectedCallback. Since some components can be out of sync
       * (due to interdependence on light children that can only be processed
       * after connectedCallback and affect the initial value).
       * This method is exposed, so it can be called after they are initialized themselves.
       * Since this method will be called twice in last mentioned scenario, it must stay idempotent.
       */
      initInteractionState() {
        if (this.constructor._isPrefilled(this.modelValue)) {
          this.prefilled = true;
        }
      }

      /**
       * Sets touched value to true
       * Reevaluates prefilled state.
       * When false, on next interaction, user will start with a clean state.
       * @private
       */
      _iStateOnLeave() {
        this.touched = true;
        this.prefilled = this.constructor._isPrefilled(this.modelValue);
      }

      /**
       * Sets dirty value and validates when already touched or invalid
       * @private
       */
      _iStateOnValueChange() {
        this.dirty = true;
      }

      /**
       * Resets touched and dirty, and recomputes prefilled
       */
      resetInteractionState() {
        this.touched = false;
        this.dirty = false;
        this.prefilled = this.constructor._isPrefilled(this.modelValue);
      }

      _onTouchedChanged() {
        this.dispatchEvent(new CustomEvent('touched-changed', { bubbles: true, composed: true }));
      }

      _onDirtyChanged() {
        this.dispatchEvent(new CustomEvent('dirty-changed', { bubbles: true, composed: true }));
      }

      /**
       * @deprecated
       */
      get leaveEvent() {
        return this._leaveEvent;
      }

      /**
       * @deprecated
       */
      set leaveEvent(eventName) {
        this._leaveEvent = eventName;
      }
    },
);