<?php

namespace Modules\Paddle\Services;

use Illuminate\Http\Client\PendingRequest;
use Illuminate\Http\Client\Response;
use Illuminate\Support\Facades\Http;
use RuntimeException;

class PaddleClient
{
    public function customer(?string $customerID): ?array
    {
        if (! $customerID || ! config('paddle.api_key')) {
            return null;
        }

        $response = $this->request()->get('/customers/'.$customerID);

        if (! $response->successful()) {
            return null;
        }

        $data = $response->json('data');

        return is_array($data) ? $data : null;
    }

    public function subscription(string $subscriptionID): array
    {
        $this->requireWritableConfiguration();

        $response = $this->request()
            ->get('/subscriptions/'.$subscriptionID);

        return $this->subscriptionData(
            $response,
            'Paddle could not retrieve the subscription.'
        );
    }

    public function updateSubscriptionPrice(
        string $subscriptionID,
        string $priceID
    ): array {
        $this->requireWritableConfiguration();

        /*
         * Paddle restricts subscription item changes while a subscription
         * is trialing. Existing item quantities may only be updated using
         * do_not_bill during the trial.
         *
         * Once the subscription is outside its trial we can use normal
         * immediate proration.
         */
        $subscription = $this->subscription($subscriptionID);

        $status = (string) ($subscription['status'] ?? '');

        $prorationBillingMode = $status === 'trialing'
            ? 'do_not_bill'
            : 'prorated_immediately';

        /*
         * Preserve the existing subscription item and replace its price.
         *
         * Paddle treats the submitted items array as the desired
         * subscription items, so quantity is retained where possible.
         */
        $existingItems = is_array($subscription['items'] ?? null)
            ? $subscription['items']
            : [];

        $existingItem = $existingItems[0] ?? [];

        $quantity = max(
            1,
            (int) ($existingItem['quantity'] ?? 1)
        );

        $response = $this->request()->patch(
            '/subscriptions/'.$subscriptionID,
            [
                'proration_billing_mode' => $prorationBillingMode,
                'items' => [
                    [
                        'price_id' => $priceID,
                        'quantity' => $quantity,
                    ],
                ],
            ]
        );

        return $this->subscriptionData(
            $response,
            'Paddle could not update the subscription.'
        );
    }

    public function cancelSubscriptionImmediately(
        string $subscriptionID
    ): array {
        $this->requireWritableConfiguration();

        $response = $this->request()->post(
            '/subscriptions/'.$subscriptionID.'/cancel',
            [
                'effective_from' => 'immediately',
            ]
        );

        return $this->subscriptionData(
            $response,
            'Paddle could not cancel the subscription.'
        );
    }

    private function request(): PendingRequest
    {
        return Http::baseUrl(
            (string) config('paddle.api_url')
        )
            ->withToken(
                (string) config('paddle.api_key')
            )
            ->acceptJson()
            ->timeout(15);
    }

    private function requireWritableConfiguration(): void
    {
        if (
            trim(
                (string) config('paddle.api_key')
            ) === ''
        ) {
            throw new RuntimeException(
                'Paddle subscription management is not configured.'
            );
        }
    }

    private function subscriptionData(
        Response $response,
        string $fallback
    ): array {
        if (! $response->successful()) {
            $detail = trim(
                (string) (
                    $response->json('error.detail')
                    ?? ''
                )
            );

            throw new RuntimeException(
                $detail !== ''
                    ? $detail
                    : $fallback
            );
        }

        $data = $response->json('data');

        if (! is_array($data)) {
            throw new RuntimeException($fallback);
        }

        return $data;
    }
}