<?php
require_once __DIR__ . '/../classes_ac/PostingWindowGuard.php';
require_once __DIR__ . '/../classes_ac/GlManager.php';

class ReceiptManager {

    private PDO $pdo;
    private int $company_id;

    public function __construct(PDO $pdo, int $company_id) {
        $this->pdo = $pdo;
        $this->company_id = $company_id;
    }

    private function generateReceiptNumber(): string
    {
        $prefix = 'RC-' . date('Ymd') . '-';
        $sth = $this->pdo->prepare(
            "SELECT receipt_number FROM td_receipt
             WHERE company_id = :company_id
               AND receipt_number LIKE :prefix
             ORDER BY receipt_number DESC
             LIMIT 1"
        );
        $sth->execute([
            ':company_id' => $this->company_id,
            ':prefix'     => $prefix . '%',
        ]);
        $last = $sth->fetchColumn();
        $seq = $last ? ((int)substr($last, -4) + 1) : 1;
        return $prefix . str_pad($seq, 4, '0', STR_PAD_LEFT);
    }

    private function assertPostingWindow(?string $date, string $context): void
    {
        global $pdo1;

        if (!isset($pdo1) || !($pdo1 instanceof PDO)) {
            throw new Exception("Posting-window validation is unavailable.");
        }

        $guard = new PostingWindowGuard($pdo1, $this->company_id);
        $guard->assertOpenDate($date ?: date('Y-m-d'), $context);
    }

    private function allocatedAmount(int $invoice_id): float
    {
        $sth = $this->pdo->prepare(
            "SELECT COALESCE(SUM(a.amount), 0)
             FROM td_receipt_item a
             JOIN td_receipt r
               ON r.company_id = a.company_id
              AND r.id = a.receipt_id
             WHERE a.company_id = :company_id
               AND a.invoice_id = :invoice_id
               AND r.status = 1"
        );
        $sth->execute([
            ':company_id' => $this->company_id,
            ':invoice_id' => $invoice_id,
        ]);
        return (float)$sth->fetchColumn();
    }

    private function refreshInvoiceSettlementStatus(int $invoice_id): void
    {
        $sth = $this->pdo->prepare(
            "SELECT grand_total, status FROM td_invoice
             WHERE company_id = :company_id AND id = :id"
        );
        $sth->execute([':company_id' => $this->company_id, ':id' => $invoice_id]);
        $row = $sth->fetch(PDO::FETCH_ASSOC);
        if (!$row || (int)$row['status'] === 4 || (int)$row['status'] === 0) return;

        $target = abs((float)$row['grand_total']);
        $paid = $this->allocatedAmount($invoice_id);
        $new_status = ($target > 0 && $paid + 0.0001 >= $target) ? 2 : 1;

        $this->pdo->prepare(
            "UPDATE td_invoice SET status = :status
             WHERE company_id = :company_id AND id = :id"
        )->execute([
            ':status'     => $new_status,
            ':company_id' => $this->company_id,
            ':id'         => $invoice_id,
        ]);
    }

    private function refreshReceiptBillingStatus(int $billing_id): void
    {
        if ($billing_id <= 0) return;

        $sth = $this->pdo->prepare(
            "SELECT b.amount, b.status,
                    COALESCE(SUM(CASE WHEN r.status = 1 THEN r.amount ELSE 0 END), 0) AS received_amount
             FROM td_receipt_billing b
             LEFT JOIN td_receipt r
               ON r.company_id = b.company_id
              AND r.receipt_billing_id = b.id
             WHERE b.company_id = :company_id
               AND b.id = :id
             GROUP BY b.id"
        );
        $sth->execute([':company_id' => $this->company_id, ':id' => $billing_id]);
        $billing = $sth->fetch(PDO::FETCH_ASSOC);
        if (!$billing || (int)$billing['status'] === 4) return;

        $amount = (float)$billing['amount'];
        $received = (float)$billing['received_amount'];
        if ($received + 0.0001 >= $amount) {
            $new_status = 2;
        } elseif ($received > 0.0001) {
            $new_status = 3;
        } else {
            $new_status = 1;
        }
        $this->pdo->prepare(
            "UPDATE td_receipt_billing
             SET status = :status
             WHERE company_id = :company_id
               AND id = :id"
        )->execute([
            ':status'     => $new_status,
            ':company_id' => $this->company_id,
            ':id'         => $billing_id,
        ]);
    }

    public function getOpenDocuments(int $contact_id = 0): array
    {
        $where = [
            "i.company_id = :company_id",
            "i.doc_type IN ('invoice', 'credit_note')",
            "i.status IN (1, 2)"
        ];
        $params = [':company_id' => $this->company_id];

        if ($contact_id > 0) {
            $where[] = 'i.contact_id = :contact_id';
            $params[':contact_id'] = $contact_id;
        }

        $sth = $this->pdo->prepare(
            "SELECT i.*,
                    COALESCE(c.contact_name, '') AS contact_name,
                    o.order_number,
                    COALESCE(SUM(CASE WHEN r.status = 1 THEN a.amount ELSE 0 END), 0) AS allocated_amount
             FROM td_invoice i
             LEFT JOIN md_contact c
               ON c.company_id = i.company_id
              AND c.id = i.contact_id
             LEFT JOIN td_order o
               ON o.company_id = i.company_id
              AND o.id = i.order_id
             LEFT JOIN td_receipt_item a
               ON a.company_id = i.company_id
              AND a.invoice_id = i.id
             LEFT JOIN td_receipt r
               ON r.company_id = a.company_id
              AND r.id = a.receipt_id
             WHERE " . implode(' AND ', $where) . "
             GROUP BY i.id
             ORDER BY i.issued_date ASC, i.id ASC"
        );
        $sth->execute($params);
        $rows = $sth->fetchAll(PDO::FETCH_ASSOC);

        $open = [];
        foreach ($rows as $row) {
            $total = abs((float)$row['grand_total']);
            $allocated = (float)$row['allocated_amount'];
            $balance = max(0, $total - $allocated);
            if ($balance <= 0.0001) continue;
            $row['document_total'] = $total;
            $row['balance_amount'] = $balance;
            $open[] = $row;
        }

        return $open;
    }

    public function getReceiptList(): array
    {
        $sth = $this->pdo->prepare(
            "SELECT r.*,
                    COALESCE(c.contact_name, '') AS contact_name,
                    COALESCE(b.billing_number, '') AS billing_number
             FROM td_receipt r
             LEFT JOIN md_contact c
               ON c.company_id = r.company_id
              AND c.id = r.contact_id
             LEFT JOIN td_receipt_billing b
               ON b.company_id = r.company_id
              AND b.id = r.receipt_billing_id
             WHERE r.company_id = :company_id
             ORDER BY r.id DESC"
        );
        $sth->execute([':company_id' => $this->company_id]);
        return $sth->fetchAll(PDO::FETCH_ASSOC);
    }

    public function getReceiptById(int $receipt_id): array
    {
        $sth = $this->pdo->prepare(
            "SELECT r.*,
                    COALESCE(c.contact_name, '') AS contact_name,
                    COALESCE(b.billing_number, '') AS billing_number
             FROM td_receipt r
             LEFT JOIN md_contact c
               ON c.company_id = r.company_id
              AND c.id = r.contact_id
             LEFT JOIN td_receipt_billing b
               ON b.company_id = r.company_id
              AND b.id = r.receipt_billing_id
             WHERE r.company_id = :company_id
               AND r.id = :id"
        );
        $sth->execute([
            ':company_id' => $this->company_id,
            ':id'         => $receipt_id,
        ]);
        $receipt = $sth->fetch(PDO::FETCH_ASSOC);
        if (!$receipt) throw new Exception("Receipt not found.");

        $sth = $this->pdo->prepare(
            "SELECT a.*,
                    i.invoice_number,
                    i.order_id,
                    i.grand_total,
                    i.status AS invoice_status,
                    o.order_number
             FROM td_receipt_item a
             JOIN td_invoice i
               ON i.company_id = a.company_id
              AND i.id = a.invoice_id
             LEFT JOIN td_order o
               ON o.company_id = i.company_id
              AND o.id = i.order_id
             WHERE a.company_id = :company_id
               AND a.receipt_id = :receipt_id
             ORDER BY a.id ASC"
        );
        $sth->execute([
            ':company_id' => $this->company_id,
            ':receipt_id' => $receipt_id,
        ]);

        $receipt['allocations'] = $sth->fetchAll(PDO::FETCH_ASSOC);
        return $receipt;
    }

    public function voidReceipt(int $receipt_id, array $logging): void
    {
        $sth = $this->pdo->prepare(
            "SELECT id, receipt_billing_id, receipt_date, status, `log`
             FROM td_receipt
             WHERE company_id = :company_id
               AND id = :id
             FOR UPDATE"
        );
        $sth->execute([
            ':company_id' => $this->company_id,
            ':id'         => $receipt_id,
        ]);
        $receipt = $sth->fetch(PDO::FETCH_ASSOC);
        if (!$receipt) throw new Exception("Receipt not found.");
        if ((int)$receipt['status'] === 4) throw new Exception("Receipt is already void.");
        $this->assertPostingWindow($receipt['receipt_date'] ?: date('Y-m-d'), 'Receipt');

        $log = json_decode($receipt['log'] ?: '[]', true);
        if (!is_array($log)) $log = [];
        $log[] = array_merge($logging, ['action' => 'void_receipt']);

        $this->pdo->prepare(
            "UPDATE td_receipt
             SET status = 4, `log` = :log
             WHERE company_id = :company_id
               AND id = :id"
        )->execute([
            ':log'        => json_encode($log),
            ':company_id' => $this->company_id,
            ':id'         => $receipt_id,
        ]);

        global $pdo1;
        $guard = new PostingWindowGuard($pdo1, $this->company_id);
        $gl = new GlManager($this->pdo, $this->company_id, $guard);
        $gl->delete('receipt', $receipt_id);

        $sth = $this->pdo->prepare(
            "SELECT invoice_id
             FROM td_receipt_item
             WHERE company_id = :company_id
               AND receipt_id = :receipt_id"
        );
        $sth->execute([
            ':company_id' => $this->company_id,
            ':receipt_id' => $receipt_id,
        ]);
        foreach ($sth->fetchAll(PDO::FETCH_COLUMN) as $invoice_id) {
            $this->refreshInvoiceSettlementStatus((int)$invoice_id);
        }
        $this->refreshReceiptBillingStatus((int)$receipt['receipt_billing_id']);
    }

    public function createReceipt(array $data, array $logging): int
    {
        $billing_id = (int)($data['receipt_billing_id'] ?? $data['billing_id'] ?? 0);
        $receipt_date = $data['receipt_date'] ?? date('Y-m-d');
        $this->assertPostingWindow($receipt_date, 'Receipt');
        $payment_method = trim((string)($data['payment_method'] ?? ''));
        $notes = trim((string)($data['notes'] ?? ''));
        $cash_amount = round((float)($data['amount'] ?? 0), 4);
        $allocations = $data['allocations'] ?? [];

        if (is_string($allocations)) {
            $allocations = json_decode($allocations, true) ?: [];
        }

        if ($billing_id <= 0) throw new Exception("Receipt billing is required.");

        $sth = $this->pdo->prepare(
            "SELECT b.*,
                    COALESCE(SUM(CASE WHEN r.status = 1 THEN r.amount ELSE 0 END), 0) AS received_amount
             FROM td_receipt_billing b
             LEFT JOIN td_receipt r
               ON r.company_id = b.company_id
              AND r.receipt_billing_id = b.id
             WHERE b.company_id = :company_id
               AND b.id = :id
             GROUP BY b.id
             FOR UPDATE"
        );
        $sth->execute([':company_id' => $this->company_id, ':id' => $billing_id]);
        $billing = $sth->fetch(PDO::FETCH_ASSOC);
        if (!$billing) throw new Exception("Receipt billing not found.");
        if ((int)$billing['status'] === 4) throw new Exception("Cannot receive against a void receipt billing.");

        $contact_id = (int)$billing['contact_id'];
        $billing_balance = round((float)$billing['amount'] - (float)$billing['received_amount'], 4);
        if ($billing_balance <= 0.0001) throw new Exception("Receipt billing is already settled.");
        if ($cash_amount - $billing_balance > 0.0001) {
            throw new Exception("Receipt amount exceeds receipt billing balance.");
        }

        $sth = $this->pdo->prepare(
            "SELECT ba.invoice_id, ba.doc_type, COALESCE(i.department_id, 0) AS department_id, ba.amount,
                    COALESCE(SUM(CASE WHEN r.status = 1 THEN ra.amount ELSE 0 END), 0) AS received_line_amount
             FROM td_receipt_billing_item ba
             JOIN td_invoice i
               ON i.company_id = ba.company_id
              AND i.id = ba.invoice_id
             LEFT JOIN td_receipt_item ra
               ON ra.company_id = ba.company_id
              AND ra.invoice_id = ba.invoice_id
             LEFT JOIN td_receipt r
               ON r.company_id = ra.company_id
              AND r.id = ra.receipt_id
              AND r.receipt_billing_id = ba.billing_id
             WHERE ba.company_id = :company_id
               AND ba.billing_id = :billing_id
             GROUP BY ba.id
             ORDER BY ba.id ASC"
        );
        $sth->execute([':company_id' => $this->company_id, ':billing_id' => $billing_id]);
        $billing_lines = $sth->fetchAll(PDO::FETCH_ASSOC);
        if (!$billing_lines) throw new Exception("Receipt billing has no documents.");

        $validated = [];
        $billing_line_map = [];
        foreach ($billing_lines as $line) {
            $billing_line_map[(int)$line['invoice_id']] = [
                'invoice_id' => (int)$line['invoice_id'],
                'doc_type'   => $line['doc_type'],
                'department_id' => (int)($line['department_id'] ?? 0),
                'remaining'  => max(0, (float)$line['amount'] - (float)$line['received_line_amount']),
            ];
        }

        if ($allocations) {
            $invoice_total = 0.0;
            $credit_total = 0.0;

            foreach ($allocations as $line) {
                $invoice_id = (int)($line['invoice_id'] ?? 0);
                $amount = abs((float)($line['amount'] ?? 0));
                if ($invoice_id <= 0 || $amount <= 0) continue;
                if (!isset($billing_line_map[$invoice_id])) {
                    throw new Exception("Receipt allocation document is not part of this billing.");
                }

                $billing_line = $billing_line_map[$invoice_id];
                if ($amount - $billing_line['remaining'] > 0.0001) {
                    throw new Exception("Receipt allocation exceeds billing line balance.");
                }

                if ($billing_line['doc_type'] === 'credit_note') $credit_total += $amount;
                else $invoice_total += $amount;

                $validated[] = [
                    'invoice_id'     => $invoice_id,
                    'doc_type'       => $billing_line['doc_type'],
                    'department_id'  => (int)($line['department_id'] ?? $billing_line['department_id'] ?? 0),
                    'amount'         => round($amount, 4),
                ];
            }

            $cash_amount = round($invoice_total - $credit_total, 4);
            if ($cash_amount <= 0) throw new Exception("Cash receipt amount must be greater than zero.");
            if ($cash_amount - $billing_balance > 0.0001) {
                throw new Exception("Receipt amount exceeds receipt billing balance.");
            }
        } else {
            if ($cash_amount <= 0) throw new Exception("Receipt amount is required.");

            $ratio = $cash_amount / max($billing_balance, 0.0001);
            foreach ($billing_lines as $line) {
                $remaining_line_amount = max(0, (float)$line['amount'] - (float)$line['received_line_amount']);
                if ($remaining_line_amount <= 0.0001) continue;

                $line_amount = round($remaining_line_amount * $ratio, 4);
                if ($line_amount <= 0) continue;
                if ($line_amount - $remaining_line_amount > 0.0001) $line_amount = $remaining_line_amount;

                $validated[] = [
                    'invoice_id'     => (int)$line['invoice_id'],
                    'doc_type'       => $line['doc_type'],
                    'department_id'  => (int)($line['department_id'] ?? 0),
                    'amount'         => $line_amount,
                ];
            }
        }

        if (!$validated) throw new Exception("Receipt billing has no remaining document balances.");

        $formula_id = isset($data['formula_id']) && (int)$data['formula_id'] > 0
            ? (int)$data['formula_id'] : null;

        $log = [array_merge($logging, ['action' => 'create_receipt'])];

        $this->pdo->prepare(
            "INSERT INTO td_receipt
                (company_id, uuid, receipt_number, contact_id, department_id, receipt_billing_id, receipt_date,
                 payment_method, amount, formula_id, status, notes, `log`, created_at)
             VALUES
                (:company_id, :uuid, :receipt_number, :contact_id, :department_id, :receipt_billing_id, :receipt_date,
                 :payment_method, :amount, :formula_id, 1, :notes, :log, :created_at)"
        )->execute([
            ':company_id'         => $this->company_id,
            ':uuid'               => bin2hex(random_bytes(16)),
            ':receipt_number'     => $this->generateReceiptNumber(),
            ':contact_id'         => $contact_id,
            ':department_id'      => (int)($data['department_id'] ?? 0),
            ':receipt_billing_id' => $billing_id,
            ':receipt_date'       => $receipt_date,
            ':payment_method'     => $payment_method,
            ':amount'             => $cash_amount,
            ':formula_id'         => $formula_id,
            ':notes'              => $notes,
            ':log'                => json_encode($log),
            ':created_at'         => date('Y-m-d H:i:s'),
        ]);

        $receipt_id = (int)$this->pdo->lastInsertId();

        foreach ($validated as $line) {
            $this->pdo->prepare(
                "INSERT INTO td_receipt_item
                    (company_id, receipt_id, invoice_id, doc_type, department_id, amount)
                 VALUES
                    (:company_id, :receipt_id, :invoice_id, :doc_type, :department_id, :amount)"
            )->execute([
                ':company_id'    => $this->company_id,
                ':receipt_id'    => $receipt_id,
                ':invoice_id'    => $line['invoice_id'],
                ':doc_type'      => $line['doc_type'],
                ':department_id' => (int)($line['department_id'] ?? 0),
                ':amount'        => $line['amount'],
            ]);

            $this->refreshInvoiceSettlementStatus($line['invoice_id']);
        }

        $this->refreshReceiptBillingStatus($billing_id);

        return $receipt_id;
    }

    public function saveFormula(int $id, ?int $formula_id): void
    {
        $sth = $this->pdo->prepare(
            "SELECT receipt_date, status FROM td_receipt
             WHERE id = :id AND company_id = :company_id"
        );
        $sth->execute([
            ':id'         => $id,
            ':company_id' => $this->company_id,
        ]);
        $receipt = $sth->fetch(PDO::FETCH_ASSOC);
        if (!$receipt) throw new Exception("Receipt not found.");
        if ((int)$receipt['status'] === 4) throw new Exception("Cannot update a void receipt.");
        $this->assertPostingWindow($receipt['receipt_date'] ?: date('Y-m-d'), 'Receipt');

        $sth = $this->pdo->prepare(
            "UPDATE td_receipt SET formula_id = :formula_id
             WHERE id = :id AND company_id = :company_id AND status != 4"
        );
        $sth->execute([
            ':formula_id' => $formula_id,
            ':id'         => $id,
            ':company_id' => $this->company_id,
        ]);
    }

    /**
     * Soft-delete a receipt by negating company_id on the header and all items.
     * Deletes the GL entry if posted. Refreshes settlement and billing status.
     */
    public function softDelete(int $receipt_id): void
    {
        $sth = $this->pdo->prepare(
            "SELECT id, receipt_billing_id, receipt_date FROM td_receipt
             WHERE company_id = :cid AND id = :id LIMIT 1"
        );
        $sth->execute([':cid' => $this->company_id, ':id' => $receipt_id]);
        $receipt = $sth->fetch(PDO::FETCH_ASSOC);
        if (!$receipt) throw new Exception('Receipt not found.');

        $this->assertPostingWindow($receipt['receipt_date'] ?: date('Y-m-d'), 'Receipt deletion');

        // Collect linked invoice ids before negating
        $sth2 = $this->pdo->prepare(
            "SELECT invoice_id FROM td_receipt_item
             WHERE company_id = :cid AND receipt_id = :id"
        );
        $sth2->execute([':cid' => $this->company_id, ':id' => $receipt_id]);
        $invoice_ids = $sth2->fetchAll(PDO::FETCH_COLUMN);

        // Delete GL entry if posted (no-op if none; throws if period closed)
        global $pdo1;
        if (isset($pdo1) && $pdo1 instanceof PDO) {
            $guard = new PostingWindowGuard($pdo1, $this->company_id);
            $gl = new GlManager($this->pdo, $this->company_id, $guard);
            $gl->delete('receipt', $receipt_id);
        }

        $this->pdo->prepare(
            "UPDATE td_receipt_item SET company_id = company_id * -1
             WHERE receipt_id = :id AND company_id = :cid"
        )->execute([':id' => $receipt_id, ':cid' => $this->company_id]);

        $this->pdo->prepare(
            "UPDATE td_receipt SET company_id = company_id * -1
             WHERE id = :id AND company_id = :cid"
        )->execute([':id' => $receipt_id, ':cid' => $this->company_id]);

        foreach ($invoice_ids as $invoice_id) {
            $this->refreshInvoiceSettlementStatus((int)$invoice_id);
        }
        $this->refreshReceiptBillingStatus((int)$receipt['receipt_billing_id']);
    }
}
?>