<?php
/**
 * AssetCategoryManager
 *
 * Asset categories decide the asset class (tangible = depreciation,
 * intangible = amortization), the default useful life, and every GL account
 * the Asset Management postings use.
 */
class AssetCategoryManager
{
    public const CLASSES = ['tangible', 'intangible'];

    public const ACCOUNT_FIELDS = [
        'cost_account_code'    => 'Asset cost account',
        'accum_account_code'   => 'Accumulated depreciation / amortization account',
        'expense_account_code' => 'Depreciation / amortization expense account',
        'gain_account_code'    => 'Gain on disposal account',
        'loss_account_code'    => 'Loss on disposal account',
    ];

    private PDO $pdo;
    private int $companyId;

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

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

    public function getAll(): array
    {
        $sth = $this->pdo->prepare(
            "SELECT c.*, COUNT(a.id) AS asset_count
             FROM md_asset_category c
             LEFT JOIN td_asset a
               ON a.company_id  = c.company_id
              AND a.category_id = c.id
              AND a.status     <> 4
             WHERE c.company_id = :cid
             GROUP BY c.id
             ORDER BY c.category_code ASC"
        );
        $sth->execute([':cid' => $this->companyId]);
        return $sth->fetchAll(PDO::FETCH_ASSOC);
    }

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

    public function save(array $data): int
    {
        $id    = (int)($data['id'] ?? 0);
        $code  = strtoupper(trim((string)($data['category_code'] ?? '')));
        $name  = trim((string)($data['category_name'] ?? ''));
        $class = trim((string)($data['asset_class'] ?? ''));
        $life  = (int)($data['useful_life_months'] ?? 0);

        if ($code === '' || $name === '') throw new Exception('Category code and name are required.');
        if (!in_array($class, self::CLASSES, true)) throw new Exception('Select tangible or intangible.');
        if ($life < 1 || $life > 1200) throw new Exception('Default useful life must be between 1 and 1200 months.');

        $accounts = [];
        foreach (self::ACCOUNT_FIELDS as $field => $label) {
            $account_code = trim((string)($data[$field] ?? ''));
            if ($account_code === '') throw new Exception("{$label} is required.");
            if (!self::isPostingAccount($this->pdo, $this->companyId, $account_code)) {
                throw new Exception("{$label} {$account_code} is not an active posting account.");
            }
            $accounts[$field] = $account_code;
        }

        $sth = $this->pdo->prepare(
            "SELECT COUNT(*) FROM md_asset_category
             WHERE company_id = :cid AND category_code = :code AND id <> :id"
        );
        $sth->execute([':cid' => $this->companyId, ':code' => $code, ':id' => $id]);
        if ((int)$sth->fetchColumn() > 0) throw new Exception("Category code {$code} already exists.");

        $params = array_merge([
            ':cid'    => $this->companyId,
            ':code'   => $code,
            ':name'   => $name,
            ':class'  => $class,
            ':life'   => $life,
            ':desc'   => trim((string)($data['description'] ?? '')),
            ':status' => (int)($data['status'] ?? 1) === 1 ? 1 : 0,
        ], [
            ':cost_acc'    => $accounts['cost_account_code'],
            ':accum_acc'   => $accounts['accum_account_code'],
            ':expense_acc' => $accounts['expense_account_code'],
            ':gain_acc'    => $accounts['gain_account_code'],
            ':loss_acc'    => $accounts['loss_account_code'],
        ]);

        if ($id) {
            $existing = $this->getById($id);
            if (!$existing) throw new Exception('Category not found.');
            if ($existing['asset_class'] !== $class && $this->countAssets($id) > 0) {
                throw new Exception('The asset class cannot change once assets use this category.');
            }

            $params[':id'] = $id;
            $this->pdo->prepare(
                "UPDATE md_asset_category SET
                    category_code = :code, category_name = :name, asset_class = :class,
                    useful_life_months = :life, description = :desc, status = :status,
                    cost_account_code = :cost_acc, accum_account_code = :accum_acc,
                    expense_account_code = :expense_acc, gain_account_code = :gain_acc,
                    loss_account_code = :loss_acc, updated_at = NOW()
                 WHERE company_id = :cid AND id = :id"
            )->execute($params);
            return $id;
        }

        $this->pdo->prepare(
            "INSERT INTO md_asset_category
                (company_id, category_code, category_name, asset_class, useful_life_months, description, status,
                 cost_account_code, accum_account_code, expense_account_code, gain_account_code, loss_account_code,
                 created_at)
             VALUES
                (:cid, :code, :name, :class, :life, :desc, :status,
                 :cost_acc, :accum_acc, :expense_acc, :gain_acc, :loss_acc,
                 NOW())"
        )->execute($params);
        return (int)$this->pdo->lastInsertId();
    }

    /** Categories are only deactivated: existing assets keep their accounts. */
    public function deactivate(int $id): void
    {
        $this->pdo->prepare(
            "UPDATE md_asset_category SET status = 0, updated_at = NOW() WHERE company_id = :cid AND id = :id"
        )->execute([':cid' => $this->companyId, ':id' => $id]);
    }

    public function getStats(): array
    {
        $sth = $this->pdo->prepare(
            "SELECT COUNT(*) AS total,
                    COALESCE(SUM(status = 1), 0) AS active,
                    COALESCE(SUM(status = 0), 0) AS inactive
             FROM md_asset_category WHERE company_id = :cid"
        );
        $sth->execute([':cid' => $this->companyId]);
        return $sth->fetch(PDO::FETCH_ASSOC) ?: [];
    }

    private function countAssets(int $category_id): int
    {
        $sth = $this->pdo->prepare(
            "SELECT COUNT(*) FROM td_asset WHERE company_id = :cid AND category_id = :id AND status <> 4"
        );
        $sth->execute([':cid' => $this->companyId, ':id' => $category_id]);
        return (int)$sth->fetchColumn();
    }
}