<?php

namespace App\Controllers\View;
use App\Controllers\BaseController;
use App\Models\PaymentNotificationLogModel;
use App\Models\UserModel;
use App\Models\ConfigurationModel;
use App\Models\InvoiceModel;
use App\Models\PaymentModel;
use App\Models\FamilyGuardianModel;
use App\Services\EmailService;
use App\Services\NotificationService;

class PaymentNotificationController extends BaseController
{
    protected PaymentNotificationLogModel $logModel;
    protected UserModel $userModel;
    protected ConfigurationModel $configModel;
    protected InvoiceModel $invoiceModel;
    protected PaymentModel $paymentModel;
    protected FamilyGuardianModel $familyGuardianModel;
    protected EmailService $emailService;

    public function __construct()
    {
        $this->logModel  = new PaymentNotificationLogModel();
        $this->userModel = new UserModel();
        $this->configModel = new ConfigurationModel();
        $this->invoiceModel = new InvoiceModel();
        $this->paymentModel = new PaymentModel();
        $this->familyGuardianModel = new FamilyGuardianModel();
        $this->emailService = new EmailService();
    }

    public function index()
    {
        helper(['form', 'url']);

        $from = $this->request->getGet('from');
        $to   = $this->request->getGet('to');
        $type = $this->request->getGet('type');

        $rows = $this->logModel->listLogs($from, $to, $type);

        // Preload parent names
        $parents = [];
        foreach ($rows as $r) {
            $pid = (int) ($r['parent_id'] ?? 0);
            if ($pid && !isset($parents[$pid])) {
                $u = $this->userModel->select('firstname,lastname')->find($pid);
                $parents[$pid] = trim(($u['firstname'] ?? '') . ' ' . ($u['lastname'] ?? ''));
            }
        }

        return view('payment/notification_management', [
            'logs'        => $rows,
            'parentsById' => $parents,
            'filters'     => ['from' => $from, 'to' => $to, 'type' => $type],
        ]);
    }

    private function wantsJson(): bool
    {
        $accept = strtolower((string)($this->request->getHeaderLine('Accept') ?? ''));
        $fmt    = strtolower((string)($this->request->getGet('format') ?? $this->request->getPost('format') ?? ''));
        return $this->request->isAJAX() || str_contains($accept, 'application/json') || $fmt === 'json';
    }

    /**
     * POST /api/payments/notifications/send
     * Body: parent_id? (int), type? ('no_payment'|'installment'), school_year?
     * - When parent_id provided: send for that parent only (if balance > 0 or force=1)
     * - Otherwise: send to all parents with positive balance for selected school year
     *   respecting idempotency (1 email per month/type) unless force=1.
     */
    public function send()
    {
        $parentId   = (int)($this->request->getPost('parent_id') ?? 0);
        $typeInput  = (string)($this->request->getPost('type') ?? '');
        $force      = (int)($this->request->getPost('force') ?? 0) === 1;
        $schoolYear = (string)($this->request->getPost('school_year') ?? ($this->configModel->getConfig('school_year') ?? date('Y')));
        $returnTo   = (string)($this->request->getPost('return_to') ?? '');

        $tzName = (string) (config('School')->attendance['timezone'] ?? user_timezone());
        $tz   = new \DateTimeZone($tzName);
        $now  = new \DateTime('now', $tz);
        $year = (int)$now->format('Y');
        $month= (int)$now->format('n');

        // Helper: compute current total balance across invoices for this parent/year
        $computeBalance = function (int $pid) use ($schoolYear): array {
            $db = \Config\Database::connect();
            $rows = $db->table('invoices')
                ->select('id, total_amount')
                ->where('parent_id', $pid)
                ->where('school_year', $schoolYear)
                ->get()->getResultArray();
            $paymentsTbl = 'payments';
            $hasStatus   = $db->fieldExists('status', $paymentsTbl);
            $hasVoid     = $db->fieldExists('is_void', $paymentsTbl);

            $sumBalance = 0.0; $latestId = null;
            foreach ($rows as $ir) {
                $iid = (int)$ir['id'];
                if ($latestId === null) $latestId = $iid;
                $total = (float)($ir['total_amount'] ?? 0);

                $qb = $db->table('payments')->select('COALESCE(SUM(paid_amount),0) AS tot')->where('invoice_id', $iid);
                if ($hasStatus) {
                    $qb->groupStart()
                        ->whereNotIn('status', ['void','voided','refunded','failed','chargeback','declined','reversed','canceled','cancelled'])
                        ->orWhere('status IS NULL', null, false)
                       ->groupEnd();
                }
                if ($hasVoid) {
                    $qb->groupStart()
                        ->where('is_void', 0)
                        ->orWhere('is_void IS NULL', null, false)
                       ->groupEnd();
                }
                $paid = (float)($qb->get()->getRowArray()['tot'] ?? 0);

                $disc = (float)($db->table('discount_usages')->select('COALESCE(SUM(discount_amount),0) AS tot')->where('invoice_id', $iid)->get()->getRowArray()['tot'] ?? 0);
                $rfnd = (float)($db->table('refunds')->select('COALESCE(SUM(refund_paid_amount),0) AS tot')->where('invoice_id', $iid)->whereIn('status', ['Partial','Paid'])->get()->getRowArray()['tot'] ?? 0);

                $sumBalance += max(0.0, round($total - $disc - $paid - $rfnd, 2));
            }
            return [$sumBalance, $latestId];
        };

        // Helper: get secondary guardian email
        $getSecondary = function (int $primaryUserId): ?string {
            $row = $this->familyGuardianModel->where('user_id', $primaryUserId)->first();
            if (!$row || empty($row['family_id'])) return null;
            $others = $this->familyGuardianModel
                ->where('family_id', (int)$row['family_id'])
                ->where('user_id !=', $primaryUserId)
                ->where('receive_emails', 1)
                ->findAll();
            foreach ($others as $g) {
                $email = $this->userModel->select('email')->find((int)$g['user_id'])['email'] ?? null;
                if ($email && filter_var($email, FILTER_VALIDATE_EMAIL)) return $email;
            }
            return null;
        };

        // Compose subject/body using same content as CLI command
        $compose = function (int $pid, float $balance) use ($schoolYear, $now): array {
            $u = $this->userModel->find($pid) ?: [];
            $parentName = trim(($u['firstname'] ?? '') . ' ' . ($u['lastname'] ?? ''));
            $greeting   = $parentName !== '' ? "Dear {$parentName}," : 'Dear Parent,';
            $monthYear  = $now->format('F Y');
            $subject    = sprintf('Monthly Tuition Reminder — %s', $schoolYear);
            $balanceFmt = '$' . number_format($balance, 2);
            $intro = 'This is your monthly installment reminder for ' . $schoolYear . '.';
            // Compute remaining/max installments similar to Manual Payment UI
            $installmentEndRaw = (string)$this->configModel->getConfig('installment_date');
            $tzName = (string) (config('School')->attendance['timezone'] ?? user_timezone());
            $tz = new \DateTimeZone($tzName);
            $today = new \DateTimeImmutable('today', $tz);
            $end = null; try { if ($installmentEndRaw) { $end = new \DateTimeImmutable($installmentEndRaw, $tz); } } catch (\Throwable $e) { $end = null; }
            $remMonths = 0;
            if ($end) {
                $y = (int)$end->format('Y') - (int)$today->format('Y');
                $m = (int)$end->format('n') - (int)$today->format('n');
                $remMonths = $y * 12 + $m;
                if ((int)$end->format('j') > (int)$today->format('j')) $remMonths += 1;
                if ($remMonths < 0) $remMonths = 0;
            }
            $remainingInst = max(1, $remMonths);
            $maxInst = max(($remMonths ?: 0), ($balance > 0 ? 2 : 0));
            $instDueFmt = '$' . number_format($remainingInst > 0 ? ($balance / $remainingInst) : 0, 2);
            $bodyHtml = <<<HTML
                <div style="font-family:Arial,Helvetica,sans-serif; font-size:14px; color:#212529; line-height:1.5;">
                  <h2 style="margin:0 0 10px; font-size:18px;">Monthly Tuition Reminder</h2>
                  <p>{$greeting}</p>
                  <p>{$intro}</p>
                  <p><strong>Current Outstanding Balance:</strong> {$balanceFmt}</p>
                  <ul>
                    <li><strong>Remaining installments:</strong> {$remainingInst}</li>
                    <li><strong>Suggested installment this month:</strong> {$instDueFmt}</li>
                    <li><strong>Maximum installments available:</strong> {$maxInst}</li>
                  </ul>
                  <p>As a friendly reminder, our tuition installments are due at the beginning of each month.</p>
                  <p>You can review your invoice and payment options by logging in to your parent portal.</p>
                  <p>Thank you for your prompt attention.</p>
                  <p><em>Reminder Period:</em> {$monthYear}</p>
                </div>
            HTML;
            $body = view('emails/_wrap_layout', [ 'title' => 'Monthly Tuition Reminder', 'body_html' => $bodyHtml ], ['saveData' => true]);
            return [$subject, $body];
        };

        $results = [ 'sent' => 0, 'skipped' => 0, 'failed' => 0, 'details' => [] ];

        if ($parentId > 0) {
            [$balance, $latestInv] = $computeBalance($parentId);

            // detect type if not provided
            if ($typeInput === 'no_payment' || $typeInput === 'installment') {
                $type = $typeInput;
            } else {
                $hasPayments = $this->paymentModel
                    ->where('parent_id', $parentId)
                    ->where('school_year', $schoolYear)
                    ->countAllResults() > 0;
                $type = $hasPayments ? 'installment' : 'no_payment';
            }

            // Idempotency: skip if already sent this month for this type
            if (!$force && $this->logModel->existsForPeriod($parentId, $year, $month, $type)) {
                $results['skipped']++;
                $results['details'][] = ['parent_id' => $parentId, 'result' => 'already_sent'];
            } else {
                
                if ($balance <= 0 && !$force) {
                    $results['skipped']++;
                    $results['details'][] = ['parent_id' => $parentId, 'result' => 'no_balance'];
                // For HTML submit, redirect back with details
                if (!$this->wantsJson()) {
                    $dest = $returnTo !== '' ? $returnTo : site_url('payment/unpaid-parents?school_year=' . rawurlencode($schoolYear));
                    return redirect()->to($dest)->with('status', 'No balance to remind this parent.');
                }
            } else {
                // Compute current-month installment suggestion
                $installmentEndRaw = (string)$this->configModel->getConfig('installment_date');
                $tzName   = (string) (config('School')->attendance['timezone'] ?? user_timezone());
                $tz   = new \DateTimeZone($tzName);
                $nowD = new \DateTimeImmutable('today', $tz);
                $endD = null; try { if ($installmentEndRaw) $endD = new \DateTimeImmutable($installmentEndRaw, $tz); } catch (\Throwable $e) { $endD = null; }
                $remMonths = 0;
                if ($endD) {
                    $y = (int)$endD->format('Y') - (int)$nowD->format('Y');
                    $m = (int)$endD->format('n') - (int)$nowD->format('n');
                    $remMonths = $y * 12 + $m;
                    if ((int)$endD->format('j') > (int)$nowD->format('j')) $remMonths += 1;
                    if ($remMonths < 0) $remMonths = 0;
                }
                $remInst = max(1, $remMonths);
                $instDue = round($balance / $remInst, 2);
                $toEmail = $this->userModel->select('email')->find($parentId)['email'] ?? null;
                $toEmail = $toEmail && filter_var($toEmail, FILTER_VALIDATE_EMAIL) ? $toEmail : null;
                $ccEmail = $getSecondary($parentId);
                [$subject, $body] = $compose($parentId, $balance);

                $ok = $toEmail ? $this->emailService->send($toEmail, $subject, $body, 'finance') : false;
                if ($ok && $ccEmail && strcasecmp($ccEmail, (string)$toEmail) !== 0) {
                    $this->emailService->send($ccEmail, $subject, $body, 'finance');
                }

                $this->logModel->insert([
                    'parent_id'        => $parentId,
                    'invoice_id'       => $latestInv,
                    'school_year'      => $schoolYear,
                    'period_year'      => $year,
                    'period_month'     => $month,
                    'type'             => $type,
                    'to_email'         => $toEmail,
                    'cc_email'         => $ccEmail,
                    'head_fa_notified' => 0,
                    'subject'          => $subject,
                    'body'             => $body,
                    'status'           => $ok ? 'sent' : 'failed',
                    'error_message'    => $ok ? null : 'Missing/invalid email or send failed',
                    'balance_snapshot' => $balance,
                    'sent_at'          => $now->format('Y-m-d H:i:s'),
                ]);

                if ($ok) { $results['sent']++; $results['details'][] = ['parent_id' => $parentId, 'result' => 'sent', 'balance' => $balance, 'installment_due' => $instDue, 'remaining' => $remInst]; }
                else { $results['failed']++; $results['details'][] = ['parent_id' => $parentId, 'result' => 'failed']; }

                // For HTML submit, redirect back with detailed message
                if (!$this->wantsJson()) {
                    $dest = $returnTo !== '' ? $returnTo : site_url('payment/unpaid-parents?school_year=' . rawurlencode($schoolYear));
                    $msg = sprintf('Reminder sent. Remaining balance: $%s. Current installment due: $%s. Remaining installments: %d',
                        number_format($balance, 2), number_format($instDue, 2), (int)$remInst);
                    return redirect()->to($dest)->with('status', $msg);
                }
            }
        }

        // Single-parent branch handled; otherwise do bulk
        } else {

        // Bulk: parents with positive balance in selected year
        $db = \Config\Database::connect();
        $rows = $db->table('invoices')
            ->select('DISTINCT parent_id', false)
            ->where('school_year', $schoolYear)
            ->get()->getResultArray();
        $pids = array_values(array_unique(array_map(static fn($r) => (int)$r['parent_id'], $rows)));

        foreach ($pids as $pid) {
            [$balance, $latestInv] = $computeBalance($pid);
            if ($balance <= 0 && !$force) { $results['skipped']++; continue; }

            $hasPayments = $this->paymentModel
                ->where('parent_id', $pid)
                ->where('school_year', $schoolYear)
                ->countAllResults() > 0;
            $type = $hasPayments ? 'installment' : 'no_payment';

            if (!$force && $this->logModel->existsForPeriod($pid, $year, $month, $type)) { $results['skipped']++; continue; }

            $toEmail = $this->userModel->select('email')->find($pid)['email'] ?? null;
            $toEmail = $toEmail && filter_var($toEmail, FILTER_VALIDATE_EMAIL) ? $toEmail : null;
            $ccEmail = $getSecondary($pid);
            [$subject, $body] = $compose($pid, $balance);

            $ok = $toEmail ? $this->emailService->send($toEmail, $subject, $body, 'finance') : false;
            if ($ok && $ccEmail && strcasecmp($ccEmail, (string)$toEmail) !== 0) {
                $this->emailService->send($ccEmail, $subject, $body, 'finance');
            }

            // Optional: notify head of finance in-app
            foreach ($this->getHeadOfFinanceUsers() as $u) {
                NotificationService::toUser((int)$u['id'], 'Payment Reminder Sent',
                    sprintf('A %s reminder was sent to parent #%d (balance: $%0.2f).', $type, $pid, $balance),
                    ['in_app']
                );
            }

            $this->logModel->insert([
                'parent_id'        => $pid,
                'invoice_id'       => $latestInv,
                'school_year'      => $schoolYear,
                'period_year'      => $year,
                'period_month'     => $month,
                'type'             => $type,
                'to_email'         => $toEmail,
                'cc_email'         => $ccEmail,
                'head_fa_notified' => 1,
                'subject'          => $subject,
                'body'             => $body,
                'status'           => $ok ? 'sent' : 'failed',
                'error_message'    => $ok ? null : 'Missing/invalid email or send failed',
                'balance_snapshot' => $balance,
                'sent_at'          => $now->format('Y-m-d H:i:s'),
            ]);

            if ($ok) $results['sent']++; else $results['failed']++;
        }

        }

        // Respond
        if ($this->wantsJson()) {
            return $this->response->setJSON(['ok' => true] + $results + [
                'csrf_token' => csrf_token(), 'csrf_hash' => csrf_hash(),
            ]);
        }

        $msg = sprintf('Reminders — sent: %d, skipped: %d, failed: %d', (int)$results['sent'], (int)$results['skipped'], (int)$results['failed']);
        $dest = $returnTo !== '' ? $returnTo : site_url('payment/unpaid-parents?school_year=' . rawurlencode($schoolYear));
        return redirect()->to($dest)->with('status', $msg);
    }

    private function getHeadOfFinanceUsers(): array
    {
        $heads = $this->userModel->getUsersByRole('head of department (finance)');
        if (!empty($heads)) return $heads;
        $acct = $this->userModel->getUsersByRole('accountant');
        return $acct ?: [];
    }
}