Kordophone/kordophone2/XPC/XPCClient.swift

//
//  XPCClient.swift
//  kordophone2
//
//  Created by James Magahern on 8/24/25.
//

import Foundation
import XPC

private let serviceName = "net.buzzert.kordophonecd"

final class XPCClient
{
    private let connection: xpc_connection_t

    init() {
        self.connection = xpc_connection_create_mach_service(serviceName, nil, 0)

        let handler: xpc_handler_t = { _ in }
        xpc_connection_set_event_handler(connection, handler)
        xpc_connection_resume(connection)
    }
    
    public func getVersion() async throws -> String {
        let req = makeRequest(method: "GetVersion")
        guard let reply = try await sendSync(req), xpc_get_type(reply) == XPC_TYPE_DICTIONARY else { throw Error.typeError }
        if let cstr = xpc_dictionary_get_string(reply, "version") {
            return String(cString: cstr)
        }
        
        throw Error.typeError
    }

    public func getConversations(limit: Int = 100, offset: Int = 0) async throws -> [Serialized.Conversation] {
        var args: [String: xpc_object_t] = [:]
        args["limit"] = xpcString(String(limit))
        args["offset"] = xpcString(String(offset))

        let req = makeRequest(method: "GetConversations", arguments: args)
        guard let reply = try await sendSync(req), xpc_get_type(reply) == XPC_TYPE_DICTIONARY else { return [] }
        guard let items = xpc_dictionary_get_value(reply, "conversations"), xpc_get_type(items) == XPC_TYPE_ARRAY else { return [] }

        var results: [Serialized.Conversation] = []
        xpc_array_apply(items) { _, element in
            if xpc_get_type(element) == XPC_TYPE_DICTIONARY, let conv = Serialized.Conversation(xpc: element) {
                results.append(conv)
            }
            return true
        }
        return results
    }
    
    // MARK: - Types
    
    enum Error: Swift.Error
    {
        case typeError
        case encodingError
    }
}

extension XPCClient
{
    private func makeRequest(method: String, arguments: [String: xpc_object_t]? = nil) -> xpc_object_t {
        let dict = xpc_dictionary_create(nil, nil, 0)
        xpc_dictionary_set_string(dict, "method", method)
        if let args = arguments {
            let argsDict = xpc_dictionary_create(nil, nil, 0)
            for (k, v) in args {
                k.withCString { cKey in
                    xpc_dictionary_set_value(argsDict, cKey, v)
                }
            }
            xpc_dictionary_set_value(dict, "arguments", argsDict)
        }
        return dict
    }

    private func xpcString(_ s: String) -> xpc_object_t {
        return s.withCString { ptr in xpc_string_create(ptr) }
    }

    private func sendSync(_ request: xpc_object_t) async throws -> xpc_object_t? {
        try await withCheckedThrowingContinuation { continuation in
            xpc_connection_send_message_with_reply(connection, request, DispatchQueue.global(qos: .userInitiated)) { r in
                switch xpc_get_type(r) {
                    case XPC_TYPE_ERROR:
                        let error = xpc_dictionary_get_value(r, "error")
                        if let error = error, let errorString = xpc_string_get_string_ptr(error) {
                            print("XPC error: \(String(cString: errorString))")
                        }
                        
                        continuation.resume(throwing: Error.typeError)

                    case XPC_TYPE_DICTIONARY:
                        continuation.resume(returning: r)
                        
                    default:
                        continuation.resume(throwing: Error.typeError)
                }
            }
        }
    }
}