TokenGenerator.swift

/**
 * FCS API - Token Generator (Swift)
 *
 * Generate secure tokens for frontend JavaScript authentication
 *
 * Usage:
 * 1. Set your accessKey and publicKey
 * 2. Call generateToken()
 * 3. Pass the token data to your frontend JavaScript
 *
 * @package FcsApi
 * @author FCS API <support@fcsapi.com>
 * @link https://fcsapi.com
 */

import Foundation
import CryptoKit

/// Token data structure
struct TokenData: Codable {
    let token: String
    let expiry: Int64
    let publicKey: String

    enum CodingKeys: String, CodingKey {
        case token = "_token"
        case expiry = "_expiry"
        case publicKey = "_public_key"
    }
}

/// Token generator for FCS API
/// Token expiry options (in seconds): 300 (5min), 900 (15min), 1800 (30min), 3600 (1hr), 86400 (24hr)
class FcsTokenGenerator {
    private let accessKey: String
    private let publicKey: String
    private let tokenExpiry: Int64

    /// Initialize token generator
    /// - Parameters:
    ///   - accessKey: Your API access key (get from https://fcsapi.com/dashboard)
    ///   - publicKey: Your public key (get from https://fcsapi.com/dashboard)
    ///   - tokenExpiry: Token expiry in seconds (default: 3600 = 1 hour)
    init(accessKey: String = "YOUR_ACCESS_KEY_HERE", publicKey: String = "YOUR_PUBLIC_KEY_HERE", tokenExpiry: Int64 = 3600) {
        self.accessKey = accessKey
        self.publicKey = publicKey
        self.tokenExpiry = tokenExpiry
    }

    /// Generate token for frontend authentication
    /// - Returns: TokenData with token, expiry, and public_key
    func generateToken() -> TokenData {
        let expiry = Int64(Date().timeIntervalSince1970) + tokenExpiry
        let message = "\(publicKey)\(expiry)"

        let key = SymmetricKey(data: Data(accessKey.utf8))
        let signature = HMAC<SHA256>.authenticationCode(for: Data(message.utf8), using: key)
        let token = signature.map { String(format: "%02x", $0) }.joined()

        return TokenData(token: token, expiry: expiry, publicKey: publicKey)
    }

    /// Generate token and return as JSON string
    /// - Returns: JSON string of token data
    func toJson() -> String? {
        let tokenData = generateToken()
        let encoder = JSONEncoder()
        guard let jsonData = try? encoder.encode(tokenData) else { return nil }
        return String(data: jsonData, encoding: .utf8)
    }

    /// Generate HTML meta tags for token
    /// - Returns: HTML meta tags string
    func getMetaTags() -> String {
        let tokenData = generateToken()
        return """
        <meta name="fcs-public-key" content="\(tokenData.publicKey)">
        <meta name="fcs-token" content="\(tokenData.token)">
        <meta name="fcs-token-expiry" content="\(tokenData.expiry)">
        """
    }
}

// ============================================
// USAGE EXAMPLES
// ============================================

// Example 1: Generate token
let generator = FcsTokenGenerator(accessKey: "your_access_key", publicKey: "your_public_key")
let tokenData = generator.generateToken()
print("Token Data: \(tokenData)")

// Example 2: Get as JSON
if let json = generator.toJson() {
    print("\nJSON: \(json)")
}

// Example 3: Get meta tags
print("\nMeta Tags:\n\(generator.getMetaTags())")

// Vapor example:
// import Vapor
//
// func routes(_ app: Application) throws {
//     app.get("fcs-token") { req -> TokenData in
//         let generator = FcsTokenGenerator(
//             accessKey: Environment.get("FCS_ACCESS_KEY") ?? "",
//             publicKey: Environment.get("FCS_PUBLIC_KEY") ?? ""
//         )
//         return generator.generateToken()
//     }
// }