// hidmon.swift - raw HID input-report monitor (IOHIDManager layer, below the event system)
// Usage: ./hidmon [product-name-substring]
//   No arg  -> matches keyboard (GD/0x06), mouse (GD/0x02), and consumer-control (0x0C/0x01) usage pairs.
//   With arg -> additionally drops devices whose Product string does not contain the substring (case-insensitive).
// Output: one line per input report: ISO timestamp | product | reportID | raw bytes hex.
// Requires the Input Monitoring TCC permission for the hosting terminal app.

import Foundation
import IOKit.hid

let nameFilter = CommandLine.arguments.count > 1 ? CommandLine.arguments[1].lowercased() : nil

let manager = IOHIDManagerCreate(kCFAllocatorDefault, IOOptionBits(kIOHIDOptionsTypeNone))

func usagePair(_ page: Int, _ usage: Int) -> CFDictionary {
    [kIOHIDDeviceUsagePageKey: page, kIOHIDDeviceUsageKey: usage] as CFDictionary
}

// Keyboard, Mouse, Consumer Control - covers every collection the dongle's composite map exposes.
IOHIDManagerSetDeviceMatchingMultiple(manager, [
    usagePair(0x01, 0x06), // Generic Desktop / Keyboard
    usagePair(0x01, 0x02), // Generic Desktop / Mouse
    usagePair(0x0C, 0x01), // Consumer / Consumer Control
] as CFArray)

let tsFmt = ISO8601DateFormatter()
tsFmt.formatOptions = [.withInternetDateTime, .withFractionalSeconds]

func product(_ device: IOHIDDevice) -> String {
    (IOHIDDeviceGetProperty(device, kIOHIDProductKey as CFString) as? String) ?? "?"
}

var reportBuffers: [IOHIDDevice: UnsafeMutablePointer] = [:]

let matchCallback: IOHIDDeviceCallback = { _, _, _, device in
    let prod = product(device)
    if let f = nameFilter, !prod.lowercased().contains(f) { return }
    let maxLen = (IOHIDDeviceGetProperty(device, kIOHIDMaxInputReportSizeKey as CFString) as? Int) ?? 64
    let buf = UnsafeMutablePointer.allocate(capacity: max(maxLen, 8))
    reportBuffers[device] = buf
    FileHandle.standardError.write("MATCHED: \(prod) (maxInputReport=\(maxLen))\n".data(using: .utf8)!)
    IOHIDDeviceRegisterInputReportCallback(device, buf, max(maxLen, 8), { _, _, sender, _, reportID, report, reportLength in
        guard let sender = sender else { return }
        let dev = Unmanaged.fromOpaque(sender).takeUnretainedValue()
        let hex = (0 ..< reportLength).map { String(format: "%02x", report[$0]) }.joined(separator: " ")
        let fmt = ISO8601DateFormatter()
        fmt.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
        print("\(fmt.string(from: Date())) | \((IOHIDDeviceGetProperty(dev, kIOHIDProductKey as CFString) as? String) ?? "?") | reportID=\(reportID) | \(hex)")
        fflush(stdout)
    }, Unmanaged.passUnretained(device).toOpaque())
}

IOHIDManagerRegisterDeviceMatchingCallback(manager, matchCallback, nil)

IOHIDManagerScheduleWithRunLoop(manager, CFRunLoopGetCurrent(), CFRunLoopMode.defaultMode.rawValue)
let openResult = IOHIDManagerOpen(manager, IOOptionBits(kIOHIDOptionsTypeNone))
if openResult != kIOReturnSuccess {
    let hexErr = String(format: "0x%08x", openResult)
    FileHandle.standardError.write("""
    IOHIDManagerOpen failed (\(hexErr)).
    If \(hexErr) == 0xe00002e2 (kIOReturnNotPermitted): grant Input Monitoring to your terminal app:
    System Settings > Privacy & Security > Input Monitoring > enable your terminal, then fully quit and relaunch it.

    """.data(using: .utf8)!)
    exit(1)
}

FileHandle.standardError.write("hidmon: open OK, waiting for input reports (Ctrl-C to stop)...\n".data(using: .utf8)!)
CFRunLoopRun()