import Foundation
import IOKit
import IOKit.hid
import CoreGraphics
import ApplicationServices

func log(_ message: String) {
    print("\(ISO8601DateFormatter().string(from: Date())) \(message)")
    fflush(stdout)
}

struct ReportSource: Hashable {
    let device: Int
    let reportID: UInt32
}

final class State {
    var buffers: [IOHIDDevice: UnsafeMutablePointer<UInt8>] = [:]
    var lastBits: [ReportSource: UInt8] = [:]
    var lastFired: [UInt8: TimeInterval] = [:]
    var opened = false
    var lastStatus = ""
}

let state = State()
let statePtr = Unmanaged.passUnretained(state).toOpaque()

func sendCommandKey(_ keyCode: CGKeyCode) {
    guard CGPreflightPostEventAccess(),
          let source = CGEventSource(stateID: .hidSystemState),
          let down = CGEvent(keyboardEventSource: source, virtualKey: keyCode, keyDown: true),
          let up = CGEvent(keyboardEventSource: source, virtualKey: keyCode, keyDown: false)
    else { return }
    down.flags = .maskCommand
    up.flags = .maskCommand
    down.post(tap: .cgSessionEventTap)
    up.post(tap: .cgSessionEventTap)
}

let tiltMask: UInt8 = 0x60
// Ignore a second press of the same tilt within this window (switch bounce).
let debounceInterval: TimeInterval = 0.12

// Preserve the supplied Razer report layout and Command+[ / Command+] mapping.
// The mouse repeats the tilt bit in every report while held, so fire only on the press edge.
let reportCallback: IOHIDReportCallback = {
    context, result, sender, _, reportID, report, reportLength in
    guard result == kIOReturnSuccess, reportLength >= 1, let context = context else { return }
    let state = Unmanaged<State>.fromOpaque(context).takeUnretainedValue()
    let source = ReportSource(device: Int(bitPattern: sender), reportID: reportID)
    let value = report[0] & tiltMask
    let pressed = value & ~(state.lastBits[source] ?? 0)
    state.lastBits[source] = value
    let now = ProcessInfo.processInfo.systemUptime
    for (mask, keyCode) in [(UInt8(0x20), CGKeyCode(33)), (UInt8(0x40), CGKeyCode(30))] where pressed & mask != 0 {
        if let last = state.lastFired[mask], now - last < debounceInterval { continue }
        state.lastFired[mask] = now
        sendCommandKey(keyCode)
    }
}

let deviceCallback: IOHIDDeviceCallback = { context, result, _, device in
    guard result == kIOReturnSuccess, let context = context else { return }
    let state = Unmanaged<State>.fromOpaque(context).takeUnretainedValue()
    guard state.buffers[device] == nil else { return }
    let reportedSize = IOHIDDeviceGetProperty(device, kIOHIDMaxInputReportSizeKey as CFString) as? NSNumber
    let bufferSize = max(64, reportedSize?.intValue ?? 64)
    let buffer = UnsafeMutablePointer<UInt8>.allocate(capacity: bufferSize)
    buffer.initialize(repeating: 0, count: bufferSize)
    state.buffers[device] = buffer
    IOHIDDeviceRegisterInputReportCallback(device, buffer, bufferSize, reportCallback, context)
    let product = IOHIDDeviceGetProperty(device, kIOHIDProductKey as CFString)
    log("Watching: \(product ?? "Razer Pro Click V2" as CFString)")
}

let removalCallback: IOHIDDeviceCallback = { context, _, _, device in
    guard let context = context else { return }
    let state = Unmanaged<State>.fromOpaque(context).takeUnretainedValue()
    let deviceKey = Int(bitPattern: Unmanaged.passUnretained(device).toOpaque())
    state.lastBits = state.lastBits.filter { $0.key.device != deviceKey }
    if let buffer = state.buffers.removeValue(forKey: device) {
        IOHIDDeviceRegisterInputReportCallback(device, buffer, 0, nil, nil)
        buffer.deallocate()
        log("Device disconnected; waiting for reconnection.")
    }
}

let manager = IOHIDManagerCreate(kCFAllocatorDefault, IOOptionBits(kIOHIDOptionsTypeNone))
let matching: [String: Any] = [kIOHIDVendorIDKey: 5426, kIOHIDProductIDKey: 209]
IOHIDManagerSetDeviceMatching(manager, matching as CFDictionary)
IOHIDManagerRegisterDeviceMatchingCallback(manager, deviceCallback, statePtr)
IOHIDManagerRegisterDeviceRemovalCallback(manager, removalCallback, statePtr)
IOHIDManagerScheduleWithRunLoop(manager, CFRunLoopGetCurrent(), CFRunLoopMode.defaultMode.rawValue)

log("Razer Tilt Mapper started. LEFT -> Command+[; RIGHT -> Command+]")

// macOS presents its own permission dialogs. The user grants access in Settings.
// Launchd restarts this app while permissions are missing, so prompt only once per build.
let buildStamp = (try? FileManager.default.attributesOfItem(atPath: CommandLine.arguments[0])[.modificationDate] as? Date)
    .map { String($0.timeIntervalSince1970) } ?? ""
if !AXIsProcessTrusted() && UserDefaults.standard.string(forKey: "promptedBuild") != buildStamp {
    let options = [kAXTrustedCheckOptionPrompt.takeUnretainedValue() as String: true]
    _ = AXIsProcessTrustedWithOptions(options as CFDictionary)
    UserDefaults.standard.set(buildStamp, forKey: "promptedBuild")
}
if IOHIDCheckAccess(kIOHIDRequestTypeListenEvent) == kIOHIDAccessTypeUnknown {
    _ = IOHIDRequestAccess(kIOHIDRequestTypeListenEvent)
}

func accessGranted() -> Bool {
    IOHIDCheckAccess(kIOHIDRequestTypeListenEvent) == kIOHIDAccessTypeGranted && CGPreflightPostEventAccess()
}

func updateAccess() {
    let inputAllowed = IOHIDCheckAccess(kIOHIDRequestTypeListenEvent) == kIOHIDAccessTypeGranted
    let outputAllowed = CGPreflightPostEventAccess()
    var status = "Input Monitoring: \(inputAllowed ? "granted" : "required"); Accessibility: \(outputAllowed ? "granted" : "required")"
    if inputAllowed && !state.opened {
        let result = IOHIDManagerOpen(manager, IOOptionBits(kIOHIDOptionsTypeNone))
        state.opened = result == kIOReturnSuccess
        if !state.opened { status += "; HID open failed: \(result)" }
    }
    if state.opened { status += "; HID manager running" }
    if status != state.lastStatus {
        log(status)
        state.lastStatus = status
    }
}

updateAccess()
// A running process may not see a new grant, so exit while access is missing and let
// launchd (KeepAlive) start a fresh process that picks it up.
let accessTimer: Timer? = accessGranted() ? nil : {
    let started = Date()
    return Timer.scheduledTimer(withTimeInterval: 3, repeats: true) { _ in
        if accessGranted() {
            log("Permissions granted; restarting to apply them.")
            exit(0)
        }
        if Date().timeIntervalSince(started) >= 20 {
            log("Permissions still missing; restarting to recheck.")
            exit(0)
        }
    }
}()
CFRunLoopRun()