import { formatCurrency } from '@automattic/number-formatters';
import { stringify } from 'qs';
import { fetchAndParse, wpcomRequest } from '../wpcom-request-controls';
import { setFeatures, setFeaturesByType, setPlanProducts, setPlans } from './actions';
import {
	TIMELESS_PLAN_FREE,
	TIMELESS_PLAN_PREMIUM,
	plansProductSlugs,
	monthlySlugs,
	annualSlugs,
	FEATURE_IDS_THAT_REQUIRE_ANNUALLY_BILLED_PLAN,
} from './constants';
import type {
	PricedAPIPlan,
	APIPlanDetail,
	PlanSimplifiedFeature,
	Plan,
	DetailsAPIResponse,
	PlanFeature,
	PlanProduct,
	PlanSlug,
	DetailsAPIFeature,
} from './types';

const MONTHLY_PLAN_BILLING_PERIOD = 31;

/**
 * Calculates the monthly price of a plan
 * Annual plans are only priced yearly
 * @param plan the plan object
 */
function getMonthlyPrice( plan: PricedAPIPlan ) {
	return formatCurrency( plan.raw_price / 12, plan.currency_code, { stripZeros: true } ) as string;
}

/**
 * Calculates the yearly price of a monthly plan
 * @param plan the plan object
 */
function getAnnualPrice( plan: PricedAPIPlan ) {
	return formatCurrency( plan.raw_price * 12, plan.currency_code, { stripZeros: true } ) as string;
}

/**
 * Formats the plan price according to 'format-currency' package rules
 * We use this for consistency in prices formats across monthly and annual plans
 * @param plan the plan object
 */
function getFormattedPrice( plan: PricedAPIPlan ) {
	return formatCurrency( plan.raw_price, plan.currency_code, { stripZeros: true } ) as string;
}

function calculateDiscounts( planProducts: PlanProduct[] ) {
	// calculate discounts
	for ( let i = 0; i < annualSlugs.length; i++ ) {
		const annualPlan = planProducts.find( ( plan ) => plan.storeSlug === annualSlugs[ i ] );
		const monthlyPlan = planProducts.find( ( plan ) => plan.storeSlug === monthlySlugs[ i ] );

		if ( annualPlan && monthlyPlan ) {
			const annualCostIfPaidMonthly = monthlyPlan.rawPrice * 12;
			const annualCostIfPaidAnnually = annualPlan.rawPrice;
			const discount = Math.floor(
				100 * ( 1 - annualCostIfPaidAnnually / annualCostIfPaidMonthly )
			);
			annualPlan.annualDiscount = discount;
			monthlyPlan.annualDiscount = discount;
		}
	}
}

function processFeatures( features: DetailsAPIFeature[] ) {
	return features.reduce(
		( features, feature ) => {
			features[ feature.id ] = {
				id: feature.id,
				name: feature.name,
				description: feature.description,
				type: 'checkbox',
				requiresAnnuallyBilledPlan:
					FEATURE_IDS_THAT_REQUIRE_ANNUALLY_BILLED_PLAN.indexOf( feature.id ) > -1,
			};
			return features;
		},
		{} as Record< string, PlanFeature >
	);
}

function featureRequiresAnnual(
	featureName: string,
	allFeaturesData: Record< string, PlanFeature >
): boolean {
	const matchedFeatureId = Object.keys( allFeaturesData ).find(
		( featureId ) => allFeaturesData[ featureId ].name === featureName
	);

	if ( matchedFeatureId ) {
		return allFeaturesData[ matchedFeatureId ].requiresAnnuallyBilledPlan;
	}

	return false;
}

function processPlanFeatures(
	planData: APIPlanDetail,
	allFeaturesData: Record< string, PlanFeature >
): PlanSimplifiedFeature[] {
	const features: PlanSimplifiedFeature[] = planData.highlighted_features.map(
		( featureName ) => ( {
			name: featureName,
			requiresAnnuallyBilledPlan: featureRequiresAnnual( featureName, allFeaturesData ),
		} )
	);

	// Features requiring an annually billed plan should be first in the array.
	features.sort(
		( a, b ) => Number( b.requiresAnnuallyBilledPlan ) - Number( a.requiresAnnuallyBilledPlan )
	);

	return features;
}

function normalizePlanProducts(
	pricedPlans: PricedAPIPlan[],
	periodAgnosticPlans: Plan[]
): PlanProduct[] {
	const plansProducts: PlanProduct[] = plansProductSlugs.reduce( ( plans, slug ) => {
		const planProduct = pricedPlans.find( ( pricedPlan ) => pricedPlan.product_slug === slug );

		if ( ! planProduct ) {
			return plans;
		}

		const periodAgnosticPlan = periodAgnosticPlans.find(
			( plan ) => plan.productIds.indexOf( planProduct.product_id ) > -1
		) as Plan;

		plans.push( {
			productId: planProduct.product_id,
			// This means that free plan is considered "annually billed"
			billingPeriod:
				planProduct.bill_period === MONTHLY_PLAN_BILLING_PERIOD ? 'MONTHLY' : 'ANNUALLY',
			periodAgnosticSlug: periodAgnosticPlan.periodAgnosticSlug,
			storeSlug: planProduct.product_slug,
			rawPrice: planProduct.raw_price,
			// Not all plans returned from /plans have a `path_slug` (e.g. monthly plans don't have)
			pathSlug: planProduct.path_slug,
			price:
				planProduct?.bill_period === MONTHLY_PLAN_BILLING_PERIOD || planProduct.raw_price === 0
					? getFormattedPrice( planProduct )
					: getMonthlyPrice( planProduct ),
			annualPrice:
				planProduct?.bill_period === MONTHLY_PLAN_BILLING_PERIOD
					? getAnnualPrice( planProduct )
					: getFormattedPrice( planProduct ),
		} );
		return plans;
	}, [] as PlanProduct[] );
	calculateDiscounts( plansProducts );
	return plansProducts;
}

export function* getSupportedPlans( locale = 'en' ) {
	const pricedPlans: PricedAPIPlan[] = yield wpcomRequest( {
		path: '/plans',
		query: stringify( { locale } ),
		apiVersion: '1.5',
	} );

	const { body: plansFeatures } = ( yield fetchAndParse(
		`https://public-api.wordpress.com/wpcom/v2/plans/details?locale=${ encodeURIComponent(
			locale
		) }`,
		{
			mode: 'cors',
			credentials: 'omit',
		}
	) ) as { body: DetailsAPIResponse };

	const features = processFeatures( plansFeatures.features );

	const periodAgnosticPlans: Plan[] = plansFeatures.plans.map( ( plan ) => {
		const planSlug = plan.nonlocalized_short_name?.toLowerCase() as PlanSlug;

		return {
			description: plan.tagline,
			features: processPlanFeatures( plan, features ),
			storage: plan.storage,
			title: plan.short_name,
			featuresSlugs: plan.features.reduce(
				( slugs, slug ) => {
					slugs[ slug ] = true;
					return slugs;
				},
				{} as Record< string, boolean >
			),
			isFree: planSlug === TIMELESS_PLAN_FREE,
			isPopular: planSlug === TIMELESS_PLAN_PREMIUM,
			periodAgnosticSlug: planSlug,
			productIds: plan.products.map( ( { plan_id } ) => plan_id ),
		};
	} );

	const planProducts = normalizePlanProducts( pricedPlans, periodAgnosticPlans );

	yield setPlans( periodAgnosticPlans, locale );
	yield setPlanProducts( planProducts );
	yield setFeatures( features, locale );
	yield setFeaturesByType( plansFeatures.features_by_type, locale );
}