<?php

namespace App\Libraries;

use App\Models\InvoiceLineModel;
use App\Models\InvoiceModel;

class InvoiceIssuanceService
{
    private \CodeIgniter\Database\BaseConnection $db;
    private InvoiceModel $invoiceModel;
    private InvoiceLineModel $invoiceLineModel;
    private InvoiceLedgerService $invoiceLedgerService;

    public function __construct(
        ?\CodeIgniter\Database\BaseConnection $db = null,
        ?InvoiceModel $invoiceModel = null,
        ?InvoiceLineModel $invoiceLineModel = null,
        ?InvoiceLedgerService $invoiceLedgerService = null
    ) {
        $this->db = $db ?? db_connect();
        $this->invoiceModel = $invoiceModel ?? new InvoiceModel();
        $this->invoiceLineModel = $invoiceLineModel ?? new InvoiceLineModel();
        $this->invoiceLedgerService = $invoiceLedgerService ?? new InvoiceLedgerService();
    }

    public function issueInvoice(IssueInvoiceCommand $command): InvoiceLedgerResult
    {
        $invoiceData = $command->invoiceData;
        if (trim((string)($invoiceData['invoice_number'] ?? '')) === '') {
            $invoiceData['invoice_number'] = $this->generateInvoiceNumber(
                (string)($invoiceData['school_year'] ?? ''),
                (int)($invoiceData['parent_id'] ?? 0)
            );
        }
        $invoiceData['status'] = FinancialStatus::INVOICE_DRAFT;
        $invoiceData['total_amount'] = $invoiceData['total_amount'] ?? number_format($command->tuitionAmount + $command->eventAmount, 2, '.', '');
        $invoiceData['balance'] = $invoiceData['balance'] ?? $invoiceData['total_amount'];

        $this->db->transBegin();

        try {
            $invoiceId = $this->invoiceModel->insert($invoiceData);
            $this->requireWrite($invoiceId, 'INVOICE_ISSUE_INSERT_FAILED', $this->invoiceModel);

            $this->db->query('SELECT id FROM invoices WHERE id = ? FOR UPDATE', [(int)$invoiceId]);

            $inserted = $this->invoiceLedgerService->issueInitialInvoiceLines(
                (int)$invoiceId,
                $command->tuitionAmount,
                $command->eventAmount,
                $command->metadata
            );
            if ($inserted <= 0) {
                throw new FinancialPersistenceException('INVOICE_ISSUE_NO_LINES');
            }

            $lineTotals = $this->db->table('invoice_lines')
                ->select('COUNT(*) AS line_count, COALESCE(SUM(line_amount_cents),0) AS total_cents')
                ->where('invoice_id', (int)$invoiceId)
                ->where('voided_at IS NULL', null, false)
                ->get()
                ->getRowArray();
            if ((int)($lineTotals['line_count'] ?? 0) !== $inserted) {
                throw new FinancialPersistenceException('INVOICE_ISSUE_LINE_COUNT_MISMATCH');
            }
            if ((int)($lineTotals['total_cents'] ?? 0) === 0) {
                throw new FinancialPersistenceException('INVOICE_ISSUE_ZERO_LINE_TOTAL');
            }

            $this->requireWrite($this->invoiceModel->update((int)$invoiceId, [
                'status' => FinancialStatus::INVOICE_ISSUED,
                'updated_at' => utc_now(),
            ]), 'INVOICE_ISSUE_STATUS_UPDATE_FAILED', $this->invoiceModel);

            $ledger = $this->invoiceLedgerService->recalculateInvoice((int)$invoiceId);
            $this->requireTransactionStatus();
            $this->db->transCommit();

            return new InvoiceLedgerResult((int)$invoiceId, 0, $ledger);
        } catch (\Throwable $e) {
            $this->db->transRollback();
            throw $e;
        }
    }

    public function generateInvoiceNumber(string $schoolYear, ?int $parentId = null): string
    {
        $prefix = $this->invoiceNumberPrefix($schoolYear, $parentId);
        do {
            $invoiceNumber = $prefix . '-' . uniqid();
            $exists = $this->db->table('invoices')
                ->where('invoice_number', $invoiceNumber)
                ->countAllResults() > 0;
        } while ($exists);

        return $invoiceNumber;
    }

    private function invoiceNumberPrefix(string $schoolYear, ?int $parentId = null): string
    {
        $year = date('y');
        if (preg_match('/^(\d{4})-\d{4}$/', $schoolYear, $matches) === 1) {
            $year = substr($matches[1], -2);
        }

        $parentSuffix = $this->parentSchoolIdSuffix((int)($parentId ?? 0));
        if ($parentSuffix !== '') {
            return 'INV-' . $year . $parentSuffix;
        }

        return 'INV-' . $year . str_pad((string) max(0, (int)($parentId ?? 0)), 5, '0', STR_PAD_LEFT);
    }

    private function parentSchoolIdSuffix(int $parentId): string
    {
        if ($parentId <= 0) {
            return '';
        }

        $row = $this->db->table('users')
            ->select('school_id')
            ->where('id', $parentId)
            ->get()
            ->getRowArray();

        $schoolId = trim((string)($row['school_id'] ?? ''));
        if (preg_match('/^\d{2}(\d{5})$/', $schoolId, $matches) === 1) {
            return $matches[1];
        }

        return '';
    }

    private function requireWrite($result, string $code, $model = null): void
    {
        if ($result === false || $result === null || $result === 0) {
            $details = is_object($model) && method_exists($model, 'errors') ? (array)$model->errors() : [];
            throw new FinancialPersistenceException($code, $details);
        }
    }

    private function requireTransactionStatus(string $code = 'TRANSACTION_FAILED'): void
    {
        if (method_exists($this->db, 'transStatus') && $this->db->transStatus() === false) {
            throw new FinancialPersistenceException($code);
        }
    }
}