import Foundation

public enum FrameCodec {
    public static let maximumFrameSize = 1_200_000

    public static func encode<T: Encodable>(_ value: T) throws -> Data {
        let encoder = PropertyListEncoder(); encoder.outputFormat = .binary
        let body = try encoder.encode(value)
        guard body.count <= maximumFrameSize else { throw UMNError.invalidFrame }
        var size = UInt32(body.count).bigEndian
        return withUnsafeBytes(of: &size) { Data($0) } + body
    }

    public static func decode<T: Decodable>(_ type: T.Type, body: Data) throws -> T {
        guard body.count <= maximumFrameSize else { throw UMNError.invalidFrame }
        return try PropertyListDecoder().decode(type, from: body)
    }

    public static func bodyLength(from prefix: Data) throws -> Int {
        guard prefix.count == 4 else { throw UMNError.invalidFrame }
        let value = prefix.reduce(UInt32(0)) { ($0 << 8) | UInt32($1) }
        guard value > 0, value <= maximumFrameSize else { throw UMNError.invalidFrame }
        return Int(value)
    }
}

public enum IPCOperation: String, Codable, Sendable {
    case status, address, peers, routes, ping, interfaceStatus
    case aliasSet, aliasRemove, aliasList
    case firewallAllow, firewallRevoke, firewallList
    case textSend, bindText, bindStream, openStream, streamData, streamClose
}

public struct IPCMessage: Codable, Sendable {
    public var version: UInt16
    public var operation: IPCOperation
    public var requestID: UUID
    public var target: String?
    public var source: String?
    public var name: String?
    public var port: UInt16?
    public var firewallProtocol: FirewallProtocol?
    public var interfaceName: String?
    public var interfaceAddress: String?
    public var interfaceMTU: UInt16?
    public var helperState: String?
    public var synchronizedRouteCount: Int?
    public var dnsState: String?
    public var streamID: UInt64?
    public var data: Data?
    public var ok: Bool?
    public var message: String?
    public var values: [String]?

    public init(operation: IPCOperation, requestID: UUID = UUID()) {
        self.version = 2; self.operation = operation; self.requestID = requestID
    }
}