<?php
/**
 * CompanySettingManager — per-company key/value configuration store.
 *
 * Table: company_setting (company_id, setting_key, value, log, updated_at)
 *
 * Current keys:
 *   default_stock_status          int     0 = draft, 1 = auto-approve on save
 *   auto_invoice_and_credit_note  int     0 = manual, 1 = auto-generate
 *   auto_complete_on_ship         int     0 = manual, 1 = auto-complete on shipped
 *   advanced_location             int     0 = simple (single location), 1 = zone/aisle/rack
 *   location_label_rack           string  label for rack / single location field
 *   location_label_zone           string  label for zone (advanced only)
 *   location_label_aisle          string  label for aisle (advanced only)
 *
 * Designed to accept new keys without schema changes.
 */
class CompanySettingManager
{
    private PDO $pdo;
    private ?PDO $transactionPdo;
    private int $company_id;

    // ── Known keys with their defaults ───────────────────────────────────────
    private const DEFAULTS = [
        'default_stock_status'        => 1,          // auto-approve by default
        'auto_invoice_and_credit_note' => 0,          // manual by default
        'auto_complete_on_ship'        => 1,          // auto-complete by default
        'advanced_location'            => 0,          // simple mode by default
        'location_label_rack'          => 'Location', // single label default
        'location_label_zone'          => 'Zone',     // advanced level 1 default
        'location_label_aisle'         => 'Aisle',    // advanced level 2 default
        'posting_open_from'            => '',         // YYYY-MM-DD; empty = no lower bound
        'posting_open_to'              => '',         // YYYY-MM-DD; empty = no upper bound
        'gl_open_from'                 => '',         // legacy alias; use posting_open_from
        'gl_open_to'                   => '',         // legacy alias; use posting_open_to
    ];

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

    // ─────────────────────────────────────────────────────────────
    // Public API
    // ─────────────────────────────────────────────────────────────

    /**
     * Return the value for a single key, or the default if not configured.
     *
     * @param string $key  Setting key.
     * @return mixed       Stored value cast to int, or the default.
     */
    public function get(string $key): mixed
    {
        $sth = $this->pdo->prepare(
            "SELECT value FROM company_setting
             WHERE company_id = :company_id AND setting_key = :setting_key
             LIMIT 1"
        );
        $sth->execute([':company_id' => $this->companyId, ':setting_key' => $key]);
        $row = $sth->fetch(PDO::FETCH_ASSOC);

        if ($row === false) {
            return self::DEFAULTS[$key] ?? null;
        }

        // Cast numeric-looking values to int for clean comparisons
        return is_numeric($row['value']) ? (int)$row['value'] : $row['value'];
    }

    /**
     * Return all settings for this company, merged with defaults.
     *
     * @return array  Associative array of key => value.
     */
    public function getAll(): array
    {
        $sth = $this->pdo->prepare(
            "SELECT setting_key, value FROM company_setting
             WHERE company_id = :company_id"
        );
        $sth->execute([':company_id' => $this->companyId]);
        $rows = $sth->fetchAll(PDO::FETCH_KEY_PAIR);

        // Merge stored values over defaults, cast numeric values
        $result = self::DEFAULTS;
        foreach ($rows as $k => $v) {
            $result[$k] = is_numeric($v) ? (int)$v : $v;
        }
        return $result;
    }

    /**
     * Return settings that are locked by existing transaction data.
     *
     * @return array  Locked key => reason pairs.
     */
    public function getTransactionLocks(): array
    {
        $locked = [];

        if (!$this->transactionPdo || $this->isLocalhostRequest()) {
            return $locked;
        }

        if ($this->hasStockTransactions()) {
            $locked['default_stock_status'] = 'stock transactions already exist';
            $locked['advanced_location'] = 'stock transactions already exist';
        }

        if ($this->hasOrderTransactions()) {
            $locked['auto_complete_on_ship'] = 'order, invoice, or return transactions already exist';
            $locked['auto_invoice_and_credit_note'] = 'order, invoice, or return transactions already exist';
        }

        return $locked;
    }

    /**
     * Upsert a single setting value.
     *
     * @param string $key
     * @param mixed  $value
     */
    public function set(string $key, mixed $value): void
    {
        // Fetch existing log to append to it
        $sth = $this->pdo->prepare(
            "SELECT log FROM company_setting
             WHERE company_id = :company_id AND setting_key = :setting_key
             LIMIT 1"
        );
        $sth->execute([':company_id' => $this->companyId, ':setting_key' => $key]);
        $existing_log   = json_decode($sth->fetchColumn() ?: '[]', true) ?: [];
        $existing_log[] = [
            'user_id' => $_SESSION['login_user_id'] ?? null,
            'dt'      => date('Y-m-d H:i:s'),
            'value'   => $value,
        ];

        $this->pdo->prepare(
            "INSERT INTO company_setting (company_id, setting_key, value, log, updated_at)
             VALUES (:company_id, :setting_key, :value, :log, NOW())
             ON DUPLICATE KEY UPDATE value = VALUES(value), log = VALUES(log), updated_at = NOW()"
        )->execute([
            ':company_id'  => $this->companyId,
            ':setting_key' => $key,
            ':value'       => $value,
            ':log'         => json_encode($existing_log),
        ]);
    }

    /**
     * Return keys whose value cannot be changed because related transactions exist.
     *
     * @param array $incoming  Requested key => value pairs.
     * @return array           Blocked key => reason pairs.
     */
    private function blockedChanges(array $incoming): array
    {
        if (!$this->transactionPdo || $this->isLocalhostRequest()) {
            return [];
        }

        $current = $this->getAll();
        $blocked = [];

        $stock_keys = [
            'default_stock_status',
            'advanced_location',
        ];

        $order_keys = [
            'auto_complete_on_ship',
            'auto_invoice_and_credit_note',
        ];

        $needs_stock_check = false;
        foreach ($stock_keys as $key) {
            if (array_key_exists($key, $incoming) && (string)$current[$key] !== (string)$incoming[$key]) {
                $needs_stock_check = true;
                break;
            }
        }

        $needs_order_check = false;
        foreach ($order_keys as $key) {
            if (array_key_exists($key, $incoming) && (string)$current[$key] !== (string)$incoming[$key]) {
                $needs_order_check = true;
                break;
            }
        }

        $has_stock_transactions = $needs_stock_check ? $this->hasStockTransactions() : false;
        $has_order_transactions = $needs_order_check ? $this->hasOrderTransactions() : false;

        if ($has_stock_transactions) {
            foreach ($stock_keys as $key) {
                if (array_key_exists($key, $incoming) && (string)$current[$key] !== (string)$incoming[$key]) {
                    $blocked[$key] = 'stock transactions already exist';
                }
            }
        }

        if ($has_order_transactions) {
            foreach ($order_keys as $key) {
                if (array_key_exists($key, $incoming) && (string)$current[$key] !== (string)$incoming[$key]) {
                    $blocked[$key] = 'order, invoice, or return transactions already exist';
                }
            }
        }

        return $blocked;
    }

    private function hasOrderTransactions(): bool
    {
        foreach (['td_order', 'td_invoice', 'td_return'] as $table) {
            if ($this->tableHasCompanyRows($table)) {
                return true;
            }
        }

        return false;
    }

    private function hasStockTransactions(): bool
    {
        if ($this->tableHasCompanyRows('etl_stock_summary')) {
            return true;
        }

        if ($this->tableHasCompanyRows('md_lot')) {
            return true;
        }

        $sth = $this->transactionPdo->prepare(
            "SELECT id FROM md_warehouse WHERE company_id = :company_id"
        );
        $sth->execute([':company_id' => $this->companyId]);
        $warehouse_ids = $sth->fetchAll(PDO::FETCH_COLUMN);

        foreach ($warehouse_ids as $warehouse_id) {
            $warehouse_id = (int)$warehouse_id;
            if ($warehouse_id > 0 && $this->tableHasCompanyRows('td_stock_' . $warehouse_id)) {
                return true;
            }
        }

        return false;
    }

    private function tableHasCompanyRows(string $table): bool
    {
        if (!$this->tableExists($table)) {
            return false;
        }

        $safe_table = str_replace('`', '``', $table);
        $sth = $this->transactionPdo->prepare(
            "SELECT COUNT(*) FROM `{$safe_table}` WHERE company_id = :company_id LIMIT 1"
        );
        $sth->execute([':company_id' => $this->companyId]);

        return (int)$sth->fetchColumn() > 0;
    }

    private function tableExists(string $table): bool
    {
        $sth = $this->transactionPdo->prepare(
            "SELECT COUNT(*)
             FROM INFORMATION_SCHEMA.TABLES
             WHERE TABLE_SCHEMA = DATABASE()
               AND TABLE_NAME = :table_name"
        );
        $sth->execute([':table_name' => $table]);

        return (int)$sth->fetchColumn() > 0;
    }

    private function isLocalhostRequest(): bool
    {
        $host = strtolower($_SERVER['HTTP_HOST'] ?? $_SERVER['SERVER_NAME'] ?? '');
        $host = preg_replace('/:\d+$/', '', $host);

        return in_array($host, ['localhost', '127.0.0.1', '::1'], true)
            || ($_SERVER['REMOTE_ADDR'] ?? '') === '127.0.0.1'
            || ($_SERVER['REMOTE_ADDR'] ?? '') === '::1';
    }

    /**
     * HTTP handler — read or update settings via AJAX.
     *
     * action: 'read'   → return all settings
     * action: 'update' → upsert one or more keys from $data
     *
     * @param array $data  Request data array.
     */
    public function handle(array $data): void
    {
        $action = $data['action'] ?? '';

        if ($action === 'read') {
            echo json_encode([
                'success' => 1,
                'output'  => $this->getAll(),
                'locked'  => $this->getTransactionLocks(),
            ]);
            exit;
        }

        if ($action === 'update') {
            $allowed = array_keys(self::DEFAULTS);
            $incoming = [];
            foreach ($allowed as $key) {
                $incoming[$key] = $data[$key] ?? self::DEFAULTS[$key];
            }

            $blocked = $this->blockedChanges($incoming);
            if (!empty($blocked)) {
                $labels = [
                    'default_stock_status'        => 'Default Stock Status',
                    'advanced_location'            => 'Advanced Location',
                    'auto_invoice_and_credit_note' => 'Invoice & Credit Note Generation',
                    'auto_complete_on_ship'        => 'Auto-Complete on Shipped',
                ];

                $names = array_map(
                    fn($key) => $labels[$key] ?? $key,
                    array_keys($blocked)
                );

                http_response_code(409);
                echo json_encode([
                    'success' => 0,
                    'message' => 'Cannot change ' . implode(', ', $names) . ' because relevant transactions already exist.',
                    'blocked' => $blocked,
                ]);
                exit;
            }

            foreach ($incoming as $key => $value) {
                if ((string)$this->get($key) !== (string)$value) {
                    $this->set($key, $value);
                }
            }
            echo json_encode(['success' => 1, 'message' => 'Settings saved.']);
            exit;
        }

        http_response_code(400);
        echo json_encode(['success' => 0, 'message' => 'Invalid action.']);
        exit;
    }
}