<?php

/**
 * ContactManager
 *
 * Encapsulates contact and contact type operations:
 * - Soft-delete with downstream validation
 *
 * Note: Methods that modify data do NOT manage their own DB transactions.
 * Callers are responsible for wrapping operations in dbTransaction() when atomicity is needed.
 */
class ContactManager {

    private $pdo;
    private $company_id;

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

    // ─────────────────────────────────────────────────────────────
    // Private helpers
    // ─────────────────────────────────────────────────────────────

    /**
     * Check if a contact_id is referenced in any active td_stock_* row.
     * Returns true if blocking stock exists.
     */
    private function hasActiveStock(int $contact_id): bool {

        $sth = $this->pdo->prepare(
            "SELECT table_name FROM information_schema.tables
             WHERE table_schema = DATABASE()
               AND table_name LIKE 'td_stock_%'"
        );
        $sth->execute();
        $tables = $sth->fetchAll(PDO::FETCH_COLUMN);

        foreach ($tables as $table) {
            $sth = $this->pdo->prepare(
                "SELECT COUNT(*) FROM `$table`
                 WHERE company_id = :company_id
                   AND contact_id = :contact_id"
            );
            $sth->execute([
                ':company_id' => $this->company_id,
                ':contact_id' => $contact_id,
            ]);
            if ($sth->fetchColumn() > 0) {
                return true;
            }
        }

        return false;
    }

    /**
     * Build a log entry array for audit context.
     */
    private function buildLogEntry(string $action): array {
        return [
            'user_id' => $_SESSION['login_user_id'] ?? null,
            'dt'      => date('Y-m-d H:i:s'),
            'login'   => isset($_SESSION['otpTime'])
                         ? date('Y-m-d H:i:s', $_SESSION['otpTime'])
                         : null,
            'action'  => $action,
        ];
    }

    // ─────────────────────────────────────────────────────────────
    // Contact type
    // ─────────────────────────────────────────────────────────────

    /**
     * Soft-delete a contact type.
     *
     * Blocks if any md_contact references this type.
     *
     * @throws Exception if contact type not found or has dependent contacts
     */
    public function deleteContactType(int $type_id): void {

        $sth = $this->pdo->prepare(
            "SELECT id, contact_type, `log` FROM md_contact_type
             WHERE company_id = :company_id AND id = :id"
        );
        $sth->execute([
            ':company_id' => $this->company_id,
            ':id'         => $type_id,
        ]);
        $row = $sth->fetch(PDO::FETCH_ASSOC);

        if (!$row) {
            throw new Exception("Contact type not found.");
        }

        // Block if any contact references this type
        $sth = $this->pdo->prepare(
            "SELECT COUNT(*) FROM md_contact
             WHERE company_id = :company_id
               AND contact_type = :type_id"
        );
        $sth->execute([
            ':company_id' => $this->company_id,
            ':type_id'    => $type_id,
        ]);

        if ($sth->fetchColumn() > 0) {
            throw new Exception(
                "Cannot delete — contact type \"{$row['contact_type']}\" " .
                "still has contacts assigned to it."
            );
        }

        // Append delete event to log
        $log   = json_decode($row['log'] ?? '[]', true) ?: [];
        $log[] = $this->buildLogEntry('delete');

        // Soft-delete
        $this->pdo->prepare(
            "UPDATE md_contact_type
             SET company_id = company_id * -1,
                 `log`      = :log
             WHERE id = :id AND company_id = :company_id"
        )->execute([
            ':log'        => json_encode($log),
            ':id'         => $type_id,
            ':company_id' => $this->company_id,
        ]);
    }

    // ─────────────────────────────────────────────────────────────
    // Contact
    // ─────────────────────────────────────────────────────────────

    /**
     * Soft-delete a contact.
     *
     * Blocks if the contact is referenced in any active td_stock_* row.
     *
     * @throws Exception if contact not found or referenced in active stock
     */
    public function deleteContact(int $contact_id): void {

        $sth = $this->pdo->prepare(
            "SELECT id, contact_name, `log` FROM md_contact
             WHERE company_id = :company_id AND id = :id"
        );
        $sth->execute([
            ':company_id' => $this->company_id,
            ':id'         => $contact_id,
        ]);
        $row = $sth->fetch(PDO::FETCH_ASSOC);

        if (!$row) {
            throw new Exception("Contact not found.");
        }

        // Block if contact is referenced in any active stock transaction
        if ($this->hasActiveStock($contact_id)) {
            throw new Exception(
                "Cannot delete — \"{$row['contact_name']}\" " .
                "is referenced in active stock transactions."
            );
        }

        // Append delete event to log
        $log   = json_decode($row['log'] ?? '[]', true) ?: [];
        $log[] = $this->buildLogEntry('delete');

        // Soft-delete
        $this->pdo->prepare(
            "UPDATE md_contact
             SET company_id = company_id * -1,
                 `log`      = :log
             WHERE id = :id AND company_id = :company_id"
        )->execute([
            ':log'        => json_encode($log),
            ':id'         => $contact_id,
            ':company_id' => $this->company_id,
        ]);
    }
}