<?php
class AccountFormulaManager
{
    private PDO $pdo;
    private int $companyId;

    private array $documentTypes = [
        'invoice',
        'credit_note',
        'receipt',
        'purchase_invoice',
        'supplier_credit_note',
        'payment',
    ];

    private array $amountKeys = ['grand_total', 'total', 'tax', 'amount'];

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

    public function getAll(): array
    {
        $sth = $this->pdo->prepare(
            "SELECT f.*,
                    COUNT(i.id) AS item_count
             FROM md_account_formula f
             LEFT JOIN md_account_formula_item i
               ON i.company_id = f.company_id
              AND i.formula_id = f.id
             WHERE f.company_id = :cid
             GROUP BY f.id
             ORDER BY f.document_type ASC, f.is_default DESC, f.formula_name ASC"
        );
        $sth->execute([':cid' => $this->companyId]);
        return $sth->fetchAll(PDO::FETCH_ASSOC);
    }

    public function getByType(string $document_type): array
    {
        $sth = $this->pdo->prepare(
            "SELECT id, formula_name, is_default
             FROM md_account_formula
             WHERE company_id = :cid
               AND document_type = :doc_type
               AND status = 1
             ORDER BY is_default DESC, formula_name ASC"
        );
        $sth->execute([':cid' => $this->companyId, ':doc_type' => $document_type]);
        return $sth->fetchAll(PDO::FETCH_ASSOC);
    }

    public function getById(int $id): ?array
    {
        $sth = $this->pdo->prepare(
            "SELECT * FROM md_account_formula
             WHERE company_id = :cid AND id = :id
             LIMIT 1"
        );
        $sth->execute([':cid' => $this->companyId, ':id' => $id]);
        $formula = $sth->fetch(PDO::FETCH_ASSOC);
        if (!$formula) return null;

        $sth = $this->pdo->prepare(
            "SELECT i.*, a.account_name, a.account_type
             FROM md_account_formula_item i
             LEFT JOIN md_account a
               ON a.company_id = i.company_id
              AND a.account_code = i.account_code
             WHERE i.company_id = :cid
               AND i.formula_id = :formula_id
             ORDER BY i.sort_order ASC, i.id ASC"
        );
        $sth->execute([':cid' => $this->companyId, ':formula_id' => $id]);
        $formula['items'] = $sth->fetchAll(PDO::FETCH_ASSOC);

        return $formula;
    }

    public function save(array $data): int
    {
        $id = (int)($data['id'] ?? 0);
        $name = trim((string)($data['formula_name'] ?? ''));
        $documentType = trim((string)($data['document_type'] ?? ''));
        $description = trim((string)($data['description'] ?? ''));
        $isDefault = (int)($data['is_default'] ?? 0) === 1 ? 1 : 0;
        $status = (int)($data['status'] ?? 1) === 1 ? 1 : 0;
        $items = $data['items'] ?? [];

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

        if ($name === '') throw new Exception('Formula name is required.');
        if (!in_array($documentType, $this->documentTypes, true)) {
            throw new Exception('Invalid document type.');
        }

        $validated = $this->validateItems($items);
        if (!$validated) throw new Exception('Formula requires at least one debit and one credit item.');

        $debitKeys = array_unique(array_column(array_filter($validated, fn($i) => $i['drcr'] === 'D'), 'amount_key'));
        $creditKeys = array_unique(array_column(array_filter($validated, fn($i) => $i['drcr'] === 'C'), 'amount_key'));
        if (!$debitKeys || !$creditKeys) {
            throw new Exception('Formula requires at least one debit and one credit item.');
        }

        if ($isDefault) {
            $this->pdo->prepare(
                "UPDATE md_account_formula
                 SET is_default = 0
                 WHERE company_id = :cid AND document_type = :document_type"
            )->execute([':cid' => $this->companyId, ':document_type' => $documentType]);
        }

        if ($id > 0) {
            $sth = $this->pdo->prepare(
                "UPDATE md_account_formula SET
                    formula_name = :formula_name,
                    document_type = :document_type,
                    description = :description,
                    is_default = :is_default,
                    status = :status,
                    updated_at = :updated_at
                 WHERE company_id = :cid AND id = :id"
            );
            $sth->execute([
                ':cid' => $this->companyId,
                ':id' => $id,
                ':formula_name' => $name,
                ':document_type' => $documentType,
                ':description' => $description !== '' ? $description : null,
                ':is_default' => $isDefault,
                ':status' => $status,
                ':updated_at' => date('Y-m-d H:i:s'),
            ]);
        } else {
            $sth = $this->pdo->prepare(
                "INSERT INTO md_account_formula
                    (company_id, formula_name, document_type, description, is_default, status, created_at)
                 VALUES
                    (:cid, :formula_name, :document_type, :description, :is_default, :status, :created_at)"
            );
            $sth->execute([
                ':cid' => $this->companyId,
                ':formula_name' => $name,
                ':document_type' => $documentType,
                ':description' => $description !== '' ? $description : null,
                ':is_default' => $isDefault,
                ':status' => $status,
                ':created_at' => date('Y-m-d H:i:s'),
            ]);
            $id = (int)$this->pdo->lastInsertId();
        }

        $this->replaceItems($id, $validated);
        return $id;
    }

    public function delete(int $id): void
    {
        $this->pdo->prepare(
            "UPDATE md_account_formula
             SET status = 0, is_default = 0, updated_at = :updated_at
             WHERE company_id = :cid AND id = :id"
        )->execute([
            ':cid' => $this->companyId,
            ':id' => $id,
            ':updated_at' => date('Y-m-d H:i:s'),
        ]);
    }

    private function validateItems(array $items): array
    {
        $validated = [];
        $sort = 1;
        foreach ($items as $item) {
            $drcr = strtoupper(trim((string)($item['drcr'] ?? '')));
            $accountCode = trim((string)($item['account_code'] ?? ''));
            $amountKey = trim((string)($item['amount_key'] ?? ''));
            $description = trim((string)($item['description'] ?? ''));

            if (!in_array($drcr, ['D', 'C'], true) || $accountCode === '' || $amountKey === '') continue;
            if (!in_array($amountKey, $this->amountKeys, true)) throw new Exception('Invalid amount key.');
            if (!$this->isPostingAccount($accountCode)) {
                throw new Exception($accountCode . ' is not an active posting account.');
            }

            $validated[] = [
                'drcr' => $drcr,
                'account_code' => $accountCode,
                'amount_key' => $amountKey,
                'description' => $description,
                'sort_order' => $sort++,
            ];
        }
        return $validated;
    }

    private function isPostingAccount(string $accountCode): bool
    {
        $sth = $this->pdo->prepare(
            "SELECT COUNT(*)
             FROM md_account
             WHERE company_id = :cid
               AND account_code = :account_code
               AND is_posting = 1
               AND status = 1"
        );
        $sth->execute([':cid' => $this->companyId, ':account_code' => $accountCode]);
        return (int)$sth->fetchColumn() > 0;
    }

    private function replaceItems(int $formulaId, array $items): void
    {
        $this->pdo->prepare(
            "DELETE FROM md_account_formula_item
             WHERE company_id = :cid AND formula_id = :formula_id"
        )->execute([':cid' => $this->companyId, ':formula_id' => $formulaId]);

        $sth = $this->pdo->prepare(
            "INSERT INTO md_account_formula_item
                (company_id, formula_id, drcr, account_code, amount_key, description, sort_order)
             VALUES
                (:cid, :formula_id, :drcr, :account_code, :amount_key, :description, :sort_order)"
        );

        foreach ($items as $item) {
            $sth->execute([
                ':cid' => $this->companyId,
                ':formula_id' => $formulaId,
                ':drcr' => $item['drcr'],
                ':account_code' => $item['account_code'],
                ':amount_key' => $item['amount_key'],
                ':description' => $item['description'] !== '' ? $item['description'] : null,
                ':sort_order' => $item['sort_order'],
            ]);
        }
    }
}
?>