<?php

declare(strict_types=1);

namespace App\Services;

use App\Models\Wallet;
use Illuminate\Support\Facades\Hash;

/**
 * YOUR VENDING LOGIC. This is the only file you edit.
 *
 * VendStack calls your backend when a customer buys something over WhatsApp,
 * USSD, Telegram or SMS. VendStack.php receives those calls, checks they are
 * genuinely from us, and hands each one to a method below. You fill in the
 * methods for the products you sell and delete the rest.
 *
 * ---------------------------------------------------------------------------
 * WHICH METHODS DO I NEED?
 * ---------------------------------------------------------------------------
 *
 *   Selling…      | Fill in
 *   --------------|-----------------------------------------------
 *   Airtime       | vend()
 *   Data          | vend() + packages()
 *   Cable TV      | vend() + packages() + billers() + validate()
 *   Electricity   | vend() + billers() + validate()
 *   Betting       | vend() + billers() + validate()
 *
 * Everything else here is optional polish — delete any method you don't want
 * and VendStack quietly drops that feature instead of failing a purchase.
 *
 * An airtime-only merchant deletes all of this except vend().
 *
 * ---------------------------------------------------------------------------
 * THE THREE RULES
 * ---------------------------------------------------------------------------
 * 1. Debit $r->total(), vend $r->amount(). total() is the product price plus
 *    your convenience fee. Debit amount() and you never collect the fee.
 * 2. Validate the PIN against $r->customerMsisdn() — the payer. For airtime
 *    and data, $r->msisdn() is the recipient and may be someone else.
 * 3. Never store or log the PIN.
 *
 * Idempotency is already handled: VendStack.php makes sure vend() runs once per
 * reference, even if we retry. You don't need to check for duplicates.
 */
class VendStackHandler
{
    /**
     * COMPLETE THE PURCHASE. This is the only required method.
     *
     * Validate the PIN, debit the wallet, deliver the product, and say what
     * happened. Return VendStack::done(...) or VendStack::failed(...).
     */
    public function vend(VendStackRequest $r): array
    {
        // ------------------------------------------------------------------
        // 1. Find the payer's wallet and check their PIN.
        // ------------------------------------------------------------------
        // TODO: replace with your own model / table.
        $wallet = Wallet::where('phone', $r->customerMsisdn())->first();

        if ($wallet === null) {
            // Tells VendStack to offer this customer sign-up (see register()).
            return VendStack::failed('No account found for this number.', 'account_not_found');
        }

        // A scheduled or recurring order arrives with NO pin — the customer
        // isn't there to type one. They pre-authorised it, and the request's
        // signature is your proof it is really from VendStack.
        //
        // Don't want unattended debits? Replace this block with:
        //     return VendStack::failed('Scheduled orders are not supported.');
        if (! $r->isScheduled()) {
            // TODO: replace with your own PIN check.
            if (! Hash::check((string) $r->pin(), $wallet->pin_hash)) {
                // "invalid_pin" lets the customer try again instead of the chat ending.
                return VendStack::failed('Incorrect PIN.', 'invalid_pin');
            }
        }

        // ------------------------------------------------------------------
        // 2. Check the balance against TOTAL, not amount.
        // ------------------------------------------------------------------
        if ($wallet->balance < $r->total()) {
            return VendStack::failed('Insufficient balance.', 'insufficient_funds');
        }

        // ------------------------------------------------------------------
        // 3. Deliver the product, then debit.
        // ------------------------------------------------------------------
        // $r->service() is one of: airtime, data, cable, power, betting.
        // Electricity always arrives as "power".
        //
        // TODO: call whatever you already use to vend. A sketch:
        //
        // $result = match ($r->service()) {
        //     'airtime' => $vendor->airtime($r->msisdn(), $r->amount()),
        //     'data'    => $vendor->data($r->msisdn(), $r->packageId()),
        //     'cable'   => $vendor->cable($r->biller(), $r->customerId(), $r->packageId()),
        //     'power'   => $vendor->power($r->biller(), $r->customerId(), $r->meterType(), $r->amount()),
        //     'betting' => $vendor->betting($r->biller(), $r->customerId(), $r->amount()),
        // };
        //
        // if (! $result->successful) {
        //     return VendStack::failed($result->message);   // nothing debited
        // }
        //
        // $wallet->decrement('balance', $r->total());       // debit TOTAL
        //
        // return VendStack::done(
        //     'Delivered',
        //     balance: $wallet->fresh()->balance,   // shown to the customer
        //     token: $result->token,                // prepaid meter token, if any
        //     units: $result->units,                // e.g. "238.1 kWh"
        // );

        throw new \LogicException('Fill in VendStackHandler::vend() with your vending logic.');
    }

    /**
     * YOUR PROVIDERS for cable, electricity and betting.
     *
     * Delete this method if you only sell airtime and data.
     *
     * Keep the labels recognizable — on WhatsApp the customer types "Ikeja
     * Electric" or "DStv" and VendStack matches that against these labels to
     * work out which id to send you.
     */
    public function billers(VendStackRequest $r): array
    {
        return VendStack::billers(match ($r->service()) {
            'cable' => [
                ['id' => 'dstv', 'label' => 'DStv'],
                ['id' => 'gotv', 'label' => 'GOtv'],
            ],
            'power' => [
                ['id' => 'ekedc', 'label' => 'Eko Electric (EKEDC)'],
                ['id' => 'ikedc', 'label' => 'Ikeja Electric (IKEDC)'],
            ],
            'betting' => [
                ['id' => 'bet9ja', 'label' => 'Bet9ja'],
            ],
            default => [],
        });
    }

    /**
     * YOUR PRICE LIST for data bundles and cable bouquets.
     *
     * Delete this method if you only sell airtime, electricity and betting.
     *
     * For data you get $r->msisdn() and work out the network yourself.
     * For cable you get $r->biller(). Amounts are whole naira — the price the
     * customer pays. The id you return comes back as $r->packageId() on vend().
     */
    public function packages(VendStackRequest $r): array
    {
        if ($r->service() === 'data') {
            // TODO: your own bundles for this number's network.
            return VendStack::packages([
                ['id' => 'd1gb', 'label' => '1GB / 30 days', 'amount' => 300],
                ['id' => 'd5gb', 'label' => '5GB / 30 days', 'amount' => 2500],
            ], network: 'MTN');
        }

        // TODO: your own bouquets for $r->biller().
        return VendStack::packages([
            ['id' => 'compact', 'label' => 'DStv Compact', 'amount' => 10500],
        ]);
    }

    /**
     * CONFIRM A METER / SMARTCARD / BETTING ID before the customer pays.
     *
     * Delete this method if you only sell airtime and data.
     *
     * VendStack shows the name you return so the customer can check they're
     * paying the right account. $r->customerId() is the meter or card number.
     */
    public function validate(VendStackRequest $r): array
    {
        // TODO: ask your provider who owns this identifier.
        // $account = $vendor->lookup($r->service(), $r->biller(), $r->customerId());
        //
        // if (! $account) {
        //     return VendStack::invalid();
        // }
        //
        // return VendStack::valid(
        //     $account->name,
        //     address: $account->address,        // optional, printed on the receipt
        //     minAmount: $account->minVend,      // optional vend limits; VendStack
        //     maxAmount: $account->maxVend,      // enforces them before calling you
        // );

        return VendStack::invalid();
    }

    /**
     * RECONCILE A TIMED-OUT PURCHASE. Optional, but strongly recommended.
     *
     * If our vend() call to you times out, the purchase may still have gone
     * through on your side. Rather than guess, we ask you here with the same
     * reference. Look it up and tell us what really happened.
     *
     * Without this method a timed-out order is reported to the customer as
     * "couldn't confirm" — never a false failure, but no confirmation either.
     */
    public function status(VendStackRequest $r): array
    {
        // TODO: look the order up by reference.
        // $order = \App\Models\Order::where('reference', $r->reference())->first();
        //
        // return VendStack::status(match ($order?->status) {
        //     'completed' => 'completed',   // it went through
        //     'failed', null => 'failed',   // it definitively did not
        //     default => 'pending',         // still settling; we'll tell the customer to check
        // }, balance: $order?->wallet_balance_after, token: $order?->token);

        return VendStack::status('pending');
    }

    /**
     * THE CUSTOMER'S WALLET BALANCE. Optional.
     *
     * Implement it and WhatsApp shows customers their balance before they pay.
     * Note this one uses $r->msisdn(), not customerMsisdn().
     */
    public function balance(VendStackRequest $r): array
    {
        // TODO: your own lookup.
        return VendStack::balance(
            (int) Wallet::where('phone', $r->msisdn())->value('balance')
        );
    }

    /**
     * WHERE CUSTOMERS TRANSFER TO TOP UP. Optional.
     *
     * Powers the "Fund Wallet" option. VendStack only displays these accounts —
     * you credit the wallet yourself when the transfer lands, from your own
     * bank webhook. Delete this and Fund Wallet reports it's unavailable.
     */
    public function accounts(VendStackRequest $r): array
    {
        // TODO: the customer's dedicated/virtual account.
        return VendStack::accounts([
            // ['bank' => 'Wema Bank', 'account_number' => '7020001111', 'account_name' => 'Your Brand / Ada Okafor'],
        ]);
    }

    /**
     * DOES THIS NUMBER HAVE AN ACCOUNT? Optional, recommended.
     *
     * Answer this and an unrecognized customer is sent to sign-up at the START
     * of the conversation, instead of hitting a dead end after choosing a
     * product and typing a PIN.
     *
     * Be precise: only an explicit false diverts them. Anything else is treated
     * as "don't know" and the conversation carries on as normal.
     */
    public function authenticate(VendStackRequest $r): array
    {
        return VendStack::accountExists(
            Wallet::where('phone', $r->phone())->exists()
        );
    }

    /**
     * SIGN A NEW CUSTOMER UP IN CHAT. Optional.
     *
     * When a number has no account, VendStack collects a name and a PIN over
     * WhatsApp and posts them here. Create the account with $r->phone() as the
     * identity and $r->pin() as their transaction PIN.
     *
     * Delete this and sign-up simply isn't offered.
     */
    public function register(VendStackRequest $r): array
    {
        // TODO: create the account.
        // \App\Models\Wallet::create([
        //     'phone' => $r->phone(),
        //     'name' => $r->name(),
        //     'pin_hash' => \Illuminate\Support\Facades\Hash::make((string) $r->pin()),
        //     'balance' => 0,
        // ]);

        return VendStack::registered(false, 'Sign-up is not available yet.');
    }
}