/* IMPORT */

import type {FragmentNode, FragmentFragment, Fragment} from '~/types';

/* HELPERS */

const NOOP_CHILDREN: Node[] = [];

/* MAIN */

const FragmentUtils = {

  make: (): Fragment => {

    return {
      values: undefined,
      length: 0
    };

  },

  makeWithNode: ( node: Node ): FragmentNode => {

    return {
      values: node,
      length: 1
    };

  },

  makeWithFragment: ( fragment: Fragment ): FragmentFragment => {

    return {
      values: fragment,
      fragmented: true,
      length: 1
    };

  },

  getChildrenFragmented: ( thiz: Fragment, children: Node[] = [] ): Node[] => {

    const {values, length} = thiz;

    if ( !length ) return children;

    if ( values instanceof Array ) {

      for ( let i = 0, l = values.length; i < l; i++ ) {

        const value = values[i];

        if ( value instanceof Node ) {

          children.push ( value );

        } else {

          FragmentUtils.getChildrenFragmented ( value, children );

        }

      }

    } else {

      if ( values instanceof Node ) {

        children.push ( values );

      } else {

        FragmentUtils.getChildrenFragmented ( values, children );

      }

    }

    return children;

  },

  getChildren: ( thiz: Fragment ): Node | Node[] => {

    if ( !thiz.length ) return NOOP_CHILDREN;

    if ( !thiz.fragmented ) return thiz.values;

    if ( thiz.length === 1 ) return FragmentUtils.getChildren ( thiz.values );

    return FragmentUtils.getChildrenFragmented ( thiz );

  },

  pushFragment: ( thiz: Fragment, fragment: Fragment ): void => {

    FragmentUtils.pushValue ( thiz, fragment );

    thiz.fragmented = true;

  },

  pushNode: ( thiz: Fragment, node: Node ): void => {

    FragmentUtils.pushValue ( thiz, node );

  },

  pushValue: ( thiz: Fragment, value: Node | Fragment ): void => {

    const {values, length} = thiz as any; //TSC

    if ( length === 0 ) {

      thiz.values = value;

    } else if ( length === 1 ) {

      thiz.values = [values, value];

    } else {

      values.push ( value );

    }

    thiz.length += 1;

  },

  replaceWithNode: ( thiz: Fragment, node: Node ): void => {

    thiz.values = node;
    delete thiz.fragmented;
    thiz.length = 1;

  },

  replaceWithFragment: ( thiz: Fragment, fragment: Fragment ): void => {

    thiz.values = fragment.values;
    thiz.fragmented = fragment.fragmented;
    thiz.length = fragment.length;

  }

};

/* EXPORT */

export default FragmentUtils;