// MotionLab: camera -> chain of Metal shader effects -> window, recording, virtual camera.
//
//   swift run -c release MotionLab [options]
//
//   --effects DIR       folder of .metal effect files (default ./effects)
//   --only a,b,c        start with exactly these effects enabled
//   --virtualcam        also send the output to the OBS virtual camera (for Meet, Zoom, ...)
//   --snapshot OUT.png  save one frame after --frames N camera frames (default 90) and exit
//   --record OUT.mp4    record --frames N camera frames (default 90) and exit
//
// In the window: s saves a screenshot, r starts/stops recording (both into ./captures), q or Esc quits.
// Effect files are reloaded when saved.

import AppKit
import MetalKit

func option(_ name: String) -> String? {
    let arguments = CommandLine.arguments
    guard let i = arguments.firstIndex(of: name), i + 1 < arguments.count else { return nil }
    return arguments[i + 1]
}

func fail(_ message: String) -> Never {
    FileHandle.standardError.write((message + "\n").data(using: .utf8)!)
    exit(1)
}

final class AppDelegate: NSObject, NSApplicationDelegate {
    var onQuit: (() -> Void)?
    func applicationShouldTerminateAfterLastWindowClosed(_ sender: NSApplication) -> Bool { true }
    func applicationWillTerminate(_ notification: Notification) { onQuit?() }
}

setvbuf(stdout, nil, _IOLBF, 0)  // show "loaded" / shader errors immediately, even when piped

guard let device = MTLCreateSystemDefaultDevice() else { fail("Metal is not available on this machine.") }
let effectsDirectory = URL(fileURLWithPath: option("--effects") ?? "effects")

let renderer: Renderer
do {
    renderer = try Renderer(device: device, camera: Camera(device: device), effectsDirectory: effectsDirectory)
} catch {
    fail("\(error)")
}
if renderer.layers.isEmpty { print("No .metal files in \(effectsDirectory.path) - showing the plain camera.") }
if let names = option("--only") {
    let unknown = renderer.enableOnly(names.split(separator: ",").map(String.init))
    if !unknown.isEmpty {
        fail("Unknown effect(s): \(unknown.joined(separator: ", ")). Available: \(renderer.layers.map(\.name).joined(separator: ", "))")
    }
}
if option("--snapshot") != nil || option("--record") != nil {
    if !renderer.failedLayers.isEmpty { fail("shader compile failed: \(renderer.failedLayers.joined(separator: ", "))") }
    renderer.snapshot = (Int(option("--frames") ?? "90") ?? 90, option("--snapshot").map { URL(fileURLWithPath: $0) })
    renderer.recordURL = option("--record").map { URL(fileURLWithPath: $0) }
}
renderer.wantsVirtualCamera = CommandLine.arguments.contains("--virtualcam")

let app = NSApplication.shared
let delegate = AppDelegate()
delegate.onQuit = { renderer.finish() }
app.delegate = delegate
app.setActivationPolicy(.regular)

let size = NSSize(width: 960 + Panel.width, height: 540)
let window = NSWindow(contentRect: NSRect(origin: .zero, size: size),
                      styleMask: [.titled, .closable, .miniaturizable, .resizable],
                      backing: .buffered, defer: false)
let view = MTKView(frame: .zero, device: device)
view.colorPixelFormat = .bgra8Unorm
view.delegate = renderer

let panel = Panel(renderer: renderer)
renderer.onLayersChanged = { panel.rebuild() }
renderer.onStatusChanged = { panel.refreshStatus() }

NSEvent.addLocalMonitorForEvents(matching: .keyDown) { event in
    if event.modifierFlags.contains(.command) { return event }
    switch event.charactersIgnoringModifiers {
    case "s": renderer.requestScreenshot()
    case "r": renderer.toggleRecording()
    case "q", "\u{1B}": app.terminate(nil)
    default: return event
    }
    return nil
}

let content = NSView(frame: NSRect(origin: .zero, size: size))
for subview in [view, panel.view] {
    subview.translatesAutoresizingMaskIntoConstraints = false
    content.addSubview(subview)
}
NSLayoutConstraint.activate([
    view.leadingAnchor.constraint(equalTo: content.leadingAnchor),
    view.topAnchor.constraint(equalTo: content.topAnchor),
    view.bottomAnchor.constraint(equalTo: content.bottomAnchor),
    view.trailingAnchor.constraint(equalTo: panel.view.leadingAnchor),
    panel.view.trailingAnchor.constraint(equalTo: content.trailingAnchor),
    panel.view.topAnchor.constraint(equalTo: content.topAnchor),
    panel.view.bottomAnchor.constraint(equalTo: content.bottomAnchor),
])

window.title = "MotionLab"
window.contentMinSize = NSSize(width: 480 + Panel.width, height: 270)
window.contentView = content
window.setContentSize(size)  // auto layout would otherwise pick its own window size
window.center()
window.makeKeyAndOrderFront(nil)
app.activate(ignoringOtherApps: true)
app.run()