<?php

namespace App\Commands;

use CodeIgniter\CLI\BaseCommand;
use CodeIgniter\CLI\CLI;
use CodeIgniter\Database\BaseConnection;

class EnrollmentCloseoutReport extends BaseCommand
{
    protected $group = 'Registration';
    protected $name = 'registration:closeout-report';
    protected $description = 'Generate end-of-registration reconciliation and closeout exception lists.';
    protected $usage = 'php spark registration:closeout-report [--school-year=2026-2027] [--json] [--export=/tmp/registration-closeout.csv]';
    protected $options = [
        '--school-year' => 'Target school year name. Defaults to the active/current configured year.',
        '--json' => 'Print machine-readable JSON.',
        '--export' => 'Write closeout exception rows to a CSV file.',
    ];

    private BaseConnection $db;

    public function run(array $params)
    {
        $this->db = \Config\Database::connect();
        $schoolYear = trim((string) (CLI::getOption('school-year') ?? ''));
        if ($schoolYear === '') {
            $schoolYear = $this->currentSchoolYear();
        }

        $report = $this->buildReport($schoolYear);
        $exportPath = $this->optionValue('export');
        if ($exportPath !== '') {
            $this->writeCsv($exportPath, $report['exceptions']);
            $report['export_path'] = $exportPath;
        }

        if (CLI::getOption('json') !== null) {
            CLI::write(json_encode($report, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES));
            return;
        }

        $this->printReport($report);
    }

    private function buildReport(string $schoolYear): array
    {
        $previousYear = $this->previousSchoolYearName($schoolYear);
        $expected = $this->expectedReturningStudents($previousYear);
        $enrolled = $this->enrolledStudents($schoolYear);
        $unsubmitted = $this->unsubmittedReturningStudents($schoolYear, $previousYear);
        $pendingEnrollments = $this->pendingEnrollments($schoolYear);
        $unresolvedFlags = $this->unresolvedFlags($schoolYear);
        $failedEmails = $this->failedEmails($schoolYear);

        $exceptions = array_merge(
            $this->exceptionRows('unsubmitted_returning_student', $unsubmitted),
            $this->exceptionRows('pending_enrollment', $pendingEnrollments),
            $this->exceptionRows('unresolved_flag', $unresolvedFlags),
            $this->exceptionRows('failed_email', $failedEmails)
        );

        $summary = [
            'expected_returning_students' => count($expected),
            'students_with_target_year_enrollment' => count($enrolled),
            'unsubmitted_returning_students' => count($unsubmitted),
            'pending_enrollments' => count($pendingEnrollments),
            'unresolved_flags' => count($unresolvedFlags),
            'failed_emails' => count($failedEmails),
            'closeout_exception_total' => count($exceptions),
        ];

        return [
            'school_year' => $schoolYear,
            'source_school_year' => $previousYear,
            'generated_at' => date('Y-m-d H:i:s'),
            'ready_to_close' => $summary['closeout_exception_total'] === 0,
            'summary' => $summary,
            'exceptions' => $exceptions,
        ];
    }

    private function expectedReturningStudents(?string $previousYear): array
    {
        if ($previousYear === null || ! $this->db->tableExists('student_class')) {
            return [];
        }

        return $this->db->table('student_class sc')
            ->select('DISTINCT sc.student_id', false)
            ->where('sc.school_year', $previousYear)
            ->get()
            ->getResultArray();
    }

    private function enrolledStudents(string $schoolYear): array
    {
        if (! $this->db->tableExists('enrollments')) {
            return [];
        }

        return $this->db->table('enrollments')
            ->select('DISTINCT student_id', false)
            ->where('school_year', $schoolYear)
            ->get()
            ->getResultArray();
    }

    private function unsubmittedReturningStudents(string $schoolYear, ?string $previousYear): array
    {
        if ($previousYear === null || ! $this->db->tableExists('student_class') || ! $this->db->tableExists('enrollments')) {
            return [];
        }

        $join = 'e.student_id = sc.student_id AND e.school_year = ' . $this->db->escape($schoolYear);

        return $this->db->table('student_class sc')
            ->select('sc.student_id, s.firstname, s.lastname, s.school_id')
            ->select('e.id AS enrollment_id, e.enrollment_status, e.admission_status, e.registration_submitted_at')
            ->join('students s', 's.id = sc.student_id', 'left')
            ->join('enrollments e', $join, 'left', false)
            ->where('sc.school_year', $previousYear)
            ->groupStart()
                ->where('e.id IS NULL')
                ->orWhere('e.registration_submitted_at IS NULL', null, false)
            ->groupEnd()
            ->groupBy('sc.student_id, s.firstname, s.lastname, s.school_id, e.id, e.enrollment_status, e.admission_status, e.registration_submitted_at')
            ->orderBy('s.lastname', 'ASC')
            ->orderBy('s.firstname', 'ASC')
            ->get()
            ->getResultArray();
    }

    private function pendingEnrollments(string $schoolYear): array
    {
        if (! $this->db->tableExists('enrollments')) {
            return [];
        }

        return $this->db->table('enrollments e')
            ->select('e.student_id, e.id AS enrollment_id, e.enrollment_status, e.admission_status, e.registration_submitted_at, e.registration_confirmed_at')
            ->select('s.firstname, s.lastname, s.school_id')
            ->join('students s', 's.id = e.student_id', 'left')
            ->where('e.school_year', $schoolYear)
            ->groupStart()
                ->where('e.enrollment_status', 'admission under review')
                ->orWhere('e.admission_status', 'pending')
                ->orWhere('e.registration_confirmed_at IS NULL', null, false)
            ->groupEnd()
            ->orderBy('s.lastname', 'ASC')
            ->orderBy('s.firstname', 'ASC')
            ->get()
            ->getResultArray();
    }

    private function unresolvedFlags(string $schoolYear): array
    {
        if (! $this->db->tableExists('enrollment_flags')) {
            return [];
        }

        return $this->db->table('enrollment_flags ef')
            ->select('ef.id AS flag_id, ef.student_id, ef.flag_type, ef.priority, ef.created_at')
            ->select('s.firstname, s.lastname, s.school_id')
            ->join('students s', 's.id = ef.student_id', 'left')
            ->where('ef.school_year', $schoolYear)
            ->where('ef.status', 'open')
            ->orderBy('ef.priority', 'DESC')
            ->orderBy('ef.created_at', 'ASC')
            ->get()
            ->getResultArray();
    }

    private function failedEmails(string $schoolYear): array
    {
        if (! $this->db->tableExists('enrollment_email_records')) {
            return [];
        }

        return $this->db->table('enrollment_email_records')
            ->select('id AS email_record_id, parent_user_id, recipient_addresses_json, delivery_status, failure_reason, retry_count, updated_at')
            ->where('school_year', $schoolYear)
            ->where('delivery_status', 'failed')
            ->orderBy('updated_at', 'DESC')
            ->get()
            ->getResultArray();
    }

    private function exceptionRows(string $type, array $rows): array
    {
        $exceptions = [];
        foreach ($rows as $row) {
            $studentName = trim((string) ($row['firstname'] ?? '') . ' ' . (string) ($row['lastname'] ?? ''));
            $exceptions[] = [
                'type' => $type,
                'student_id' => $row['student_id'] ?? '',
                'student_name' => $studentName,
                'school_id' => $row['school_id'] ?? '',
                'reference_id' => $row['enrollment_id'] ?? $row['flag_id'] ?? $row['email_record_id'] ?? '',
                'status' => $row['enrollment_status'] ?? $row['flag_type'] ?? $row['delivery_status'] ?? '',
                'detail' => $this->exceptionDetail($type, $row),
            ];
        }

        return $exceptions;
    }

    private function exceptionDetail(string $type, array $row): string
    {
        return match ($type) {
            'unsubmitted_returning_student' => empty($row['enrollment_id'])
                ? 'No target-year enrollment exists.'
                : 'Target-year enrollment exists but registration has not been submitted.',
            'pending_enrollment' => 'Enrollment status: ' . (string) ($row['enrollment_status'] ?? '') . '; admission status: ' . (string) ($row['admission_status'] ?? ''),
            'unresolved_flag' => 'Open flag priority: ' . (string) ($row['priority'] ?? ''),
            'failed_email' => 'Retry count: ' . (int) ($row['retry_count'] ?? 0) . '; reason: ' . (string) ($row['failure_reason'] ?? ''),
            default => '',
        };
    }

    private function writeCsv(string $path, array $rows): void
    {
        $directory = dirname($path);
        if ($directory !== '' && $directory !== '.' && ! is_dir($directory)) {
            throw new \RuntimeException('Export directory does not exist: ' . $directory);
        }

        $handle = fopen($path, 'wb');
        if ($handle === false) {
            throw new \RuntimeException('Unable to write export file: ' . $path);
        }

        fputcsv($handle, ['type', 'student_id', 'student_name', 'school_id', 'reference_id', 'status', 'detail']);
        foreach ($rows as $row) {
            fputcsv($handle, [
                $row['type'] ?? '',
                $row['student_id'] ?? '',
                $row['student_name'] ?? '',
                $row['school_id'] ?? '',
                $row['reference_id'] ?? '',
                $row['status'] ?? '',
                $row['detail'] ?? '',
            ]);
        }

        fclose($handle);
    }

    private function optionValue(string $name): string
    {
        $value = CLI::getOption($name);
        if (is_string($value) && trim($value) !== '') {
            return trim($value);
        }

        $argv = $_SERVER['argv'] ?? [];
        $long = '--' . $name;
        foreach ($argv as $index => $arg) {
            if (str_starts_with((string) $arg, $long . '=')) {
                return trim(substr((string) $arg, strlen($long) + 1));
            }
            if ($arg === $long && isset($argv[$index + 1]) && ! str_starts_with((string) $argv[$index + 1], '--')) {
                return trim((string) $argv[$index + 1]);
            }
        }

        return '';
    }

    private function currentSchoolYear(): string
    {
        if ($this->db->tableExists('school_years')) {
            $row = $this->db->table('school_years')
                ->select('name')
                ->where('status', 'active')
                ->orderBy('id', 'DESC')
                ->limit(1)
                ->get()
                ->getRowArray();
            if (! empty($row['name'])) {
                return (string) $row['name'];
            }
        }

        if ($this->db->tableExists('configuration')) {
            $row = $this->db->table('configuration')
                ->select('config_value')
                ->where('config_key', 'school_year')
                ->limit(1)
                ->get()
                ->getRowArray();
            if (! empty($row['config_value'])) {
                return (string) $row['config_value'];
            }
        }

        return '';
    }

    private function previousSchoolYearName(string $schoolYear): ?string
    {
        return preg_match('/^(\d{4})-(\d{4})$/', trim($schoolYear), $matches)
            ? ((int) $matches[1] - 1) . '-' . ((int) $matches[2] - 1)
            : null;
    }

    private function printReport(array $report): void
    {
        CLI::write('Registration Closeout Report: ' . (string) ($report['school_year'] ?? ''), ($report['ready_to_close'] ?? false) ? 'green' : 'yellow');
        CLI::write('Generated at: ' . (string) ($report['generated_at'] ?? ''));
        CLI::write('Ready to close: ' . (($report['ready_to_close'] ?? false) ? 'yes' : 'no'));
        CLI::newLine();

        foreach (($report['summary'] ?? []) as $key => $value) {
            CLI::write($key . ': ' . $value);
        }

        if (! empty($report['export_path'])) {
            CLI::newLine();
            CLI::write('Export written: ' . (string) $report['export_path'], 'green');
        }
    }
}