/**
 * External dependencies
 */
import { isEqual, keyBy } from 'lodash';
import { EMPTY_OBJECT } from '@nab/utils';
import type { AnyAction } from '@nab/types';

/**
 * Internal dependencies
 */
import { INIT_STATE as IS } from '../config';

import type { State as FullState } from '../types';
type State = FullState[ 'experiment' ][ 'scope' ];

import type { ScopeAction } from '../actions/scope';
import type { SetupEditor } from '../actions/editor';
type Action = ScopeAction | SetupEditor;

const INIT_STATE = IS.experiment.scope;

export function scope( state = INIT_STATE, action: AnyAction ): State {
	return actualReducer( state, action as Action ) ?? state;
}

function actualReducer( state: State, action: Action ): State {
	switch ( action.type ) {
		case 'SET_SCOPE_RULES': {
			const newRules = action.rules.map( ( rule ) =>
				state[ rule.id ] && isEqual( state[ rule.id ], rule )
					? state[ rule.id ]
					: rule
			);
			return keyBy( newRules, 'id' );
		}

		case 'SETUP_EDITOR': {
			if ( 'nab/heatmap' === action.experiment.type ) {
				return EMPTY_OBJECT;
			}

			const newState = keyBy( action.experiment.scope, 'id' );
			return isEqual( newState, state ) ? state : newState;
		}
	}
}