/**
 * External dependencies
 */
import { isEqual, keyBy, omit } from 'lodash';
import { EMPTY_OBJECT, isDefined } 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' ][ 'goals' ];

import type { GoalAction } from '../actions/goals';
import type { SetupEditor } from '../actions/editor';
type Action = GoalAction | SetupEditor;

const INIT_STATE = IS.experiment.goals;

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

function actualReducer( state: State, action: Action ): State {
	switch ( action.type ) {
		case 'ADD_GOALS': {
			const newGoals = action.goals.filter(
				( goal ) => ! isEqual( state[ goal.id ], goal )
			);
			if ( ! newGoals.length ) {
				return state;
			}
			return {
				...state,
				...keyBy( newGoals, 'id' ),
			};
		}

		case 'UPDATE_GOAL': {
			const goal = state[ action.goalId ];
			if ( ! goal ) {
				return state;
			}

			const newGoal = {
				...goal,
				attributes: {
					...goal.attributes,
					...action.attributes,
				},
			};

			if ( isEqual( goal, newGoal ) ) {
				return state;
			}

			return {
				...state,
				[ action.goalId ]: newGoal,
			};
		}

		case 'REMOVE_GOALS':
			return omit( state, action.ids );

		case 'SORT_GOALS':
			return keyBy(
				action.ids.map( ( id ) => state[ id ] ).filter( isDefined ),
				'id'
			);

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

			const newState = keyBy(
				action.experiment.goals.map( ( goal ) =>
					omit( goal, 'conversionActions' )
				),
				'id'
			);

			return isEqual( state, newState ) ? state : newState;
	}
}