//! `cargo run --example shot -- [--keys "a ctrl-c lopt-f"] <png> <program> [args…]`: runs a program in the main window, types the keys as AppKit events, then photographs the window.

#[cfg(target_os = "macos")]
fn main() {
    use std::time::Duration;

    use ely_gpui_component::Assets;
    use elyterminal::{app, term::Launch};

    env_logger::Builder::from_env(env_logger::Env::default().default_filter_or("elyterminal=info"))
        .init();
    let mut args = std::env::args().skip(1).peekable();
    let keys: Vec<String> = if args.peek().map(String::as_str) == Some("--keys") {
        args.next();
        let keys = args.next().expect("keys after --keys");
        keys.split_whitespace().map(String::from).collect()
    } else {
        Vec::new()
    };
    let out = args.next().expect("a png path");
    let program = args.next().expect("a program");
    let launch = Launch {
        program: Some((program, args.collect())),
        cwd: std::env::current_dir().expect("a current folder"),
        env: Vec::new(),
    };
    gpui_platform::application()
        .with_assets(Assets)
        .run(move |cx: &mut gpui::App| {
            ely_gpui_component::init(cx).expect("Ely starts");
            app::start(cx).expect("the app starts");
            let window = app::open(launch, cx).expect("the window opens");
            cx.activate(true);
            cx.spawn(async move |cx| {
                cx.background_executor().timer(Duration::from_secs(1)).await;
                let number = window
                    .update(cx, |_, window, _| capture::number(window))
                    .expect("the window lives")
                    .expect("a window number");
                for spec in &keys {
                    typing::post(spec, number).expect("a key event");
                    cx.background_executor()
                        .timer(Duration::from_millis(120))
                        .await;
                }
                cx.background_executor().timer(Duration::from_secs(1)).await;
                let number = window
                    .update(cx, |_, window, _| capture::number(window))
                    .expect("the window lives")
                    .expect("a window number");
                capture::snapshot(number, std::path::Path::new(&out)).expect("a picture");
                log::info!("shot: wrote {out}");
                cx.update(|cx| cx.quit());
            })
            .detach();
        });
}

#[cfg(target_os = "macos")]
mod capture {
    use std::path::Path;

    use anyhow::{Context as _, bail};
    use objc::{msg_send, runtime::Object, sel, sel_impl};
    use raw_window_handle::{HasWindowHandle, RawWindowHandle};

    /// A gpui window's number, as CoreGraphics knows it.
    pub fn number(window: &gpui::Window) -> anyhow::Result<u32> {
        let handle = HasWindowHandle::window_handle(window)
            .map_err(|error| anyhow::anyhow!("no native handle: {error:?}"))?;
        let RawWindowHandle::AppKit(appkit) = handle.as_raw() else {
            bail!("not an AppKit window");
        };
        let view = appkit.ns_view.as_ptr() as *mut Object;
        let native: *mut Object = unsafe { msg_send![view, window] };
        let number: i64 = unsafe { msg_send![native, windowNumber] };
        u32::try_from(number).context("window number out of range")
    }

    /// Writes the window `number` as a PNG; the app's own window needs no permission.
    pub fn snapshot(number: u32, path: &Path) -> anyhow::Result<()> {
        use core_graphics::{
            geometry::{CGPoint, CGRect, CGSize},
            window,
        };
        let image = window::create_image(
            CGRect::new(&CGPoint::new(0.0, 0.0), &CGSize::new(0.0, 0.0)),
            window::kCGWindowListOptionIncludingWindow,
            number,
            window::kCGWindowImageBoundsIgnoreFraming | window::kCGWindowImageBestResolution,
        )
        .context("window capture returned nothing")?;
        if image.bits_per_pixel() != 32 {
            bail!("{} bits per pixel", image.bits_per_pixel());
        }
        let (width, height, stride) = (image.width(), image.height(), image.bytes_per_row());
        let data = image.data();
        let bytes = data.bytes();
        let mut rgba = Vec::with_capacity(width * height * 4);
        for y in 0..height {
            for x in 0..width {
                let at = y * stride + x * 4;
                rgba.extend_from_slice(&[bytes[at + 2], bytes[at + 1], bytes[at], bytes[at + 3]]);
            }
        }
        image::save_buffer(
            path,
            &rgba,
            width as u32,
            height as u32,
            image::ColorType::Rgba8,
        )
        .with_context(|| format!("cannot write {}", path.display()))
    }
}

#[cfg(target_os = "macos")]
mod typing {
    use anyhow::Context as _;
    use core_graphics::geometry::CGPoint;
    use objc::{
        class, msg_send,
        runtime::{NO, Object},
        sel, sel_impl,
    };

    /// US layout key codes and what each key types.
    const KEYS: [(&str, u16, &str); 17] = [
        ("a", 0, "a"),
        ("c", 8, "c"),
        ("e", 14, "e"),
        ("f", 3, "f"),
        ("i", 34, "i"),
        ("s", 1, "s"),
        ("[", 33, "["),
        ("space", 49, " "),
        ("tab", 48, "\t"),
        ("enter", 36, "\r"),
        ("backspace", 51, "\u{7f}"),
        ("escape", 53, "\u{1b}"),
        ("up", 126, "\u{F700}"),
        ("down", 125, "\u{F701}"),
        ("left", 123, "\u{F702}"),
        ("f1", 122, "\u{F704}"),
        ("f5", 96, "\u{F708}"),
    ];

    /// Posts `spec`, such as `ctrl-c` or `lopt-f`, as a key going down and up on window `number`.
    pub fn post(spec: &str, number: u32) -> anyhow::Result<()> {
        let mut parts: Vec<&str> = spec.split('-').collect();
        let name = parts.pop().context("an empty key")?;
        let (_, code, plain) = KEYS
            .iter()
            .find(|(key, ..)| *key == name)
            .with_context(|| format!("no key code for {name}"))?;
        let mut flags: u64 = 0;
        for modifier in &parts {
            flags |= match *modifier {
                "shift" => 0x20000 | 0x02,
                "ctrl" => 0x40000 | 0x01,
                "lopt" => 0x80000 | 0x20,
                "ropt" => 0x80000 | 0x40,
                "cmd" => 0x100000 | 0x08,
                other => anyhow::bail!("no modifier {other}"),
            };
        }
        if plain
            .chars()
            .next()
            .is_some_and(|ch| ('\u{F700}'..='\u{F8FF}').contains(&ch))
        {
            flags |= 0x800000 | 0x200000;
        }
        let ignoring = if flags & 0x20000 != 0 {
            plain.to_uppercase()
        } else {
            plain.to_string()
        };
        let typed = match plain.chars().next() {
            _ if flags & 0x80000 != 0 => String::new(),
            Some(letter @ 'a'..='z') if flags & 0x40000 != 0 => {
                char::from(letter as u8 - b'a' + 1).to_string()
            }
            _ => ignoring.clone(),
        };
        for kind in [10u64, 11] {
            unsafe {
                let string = |text: &str| -> *mut Object {
                    let text = std::ffi::CString::new(text).expect("no NUL in key text");
                    msg_send![class!(NSString), stringWithUTF8String: text.as_ptr()]
                };
                let event: *mut Object = msg_send![
                    class!(NSEvent),
                    keyEventWithType: kind
                    location: CGPoint::new(0.0, 0.0)
                    modifierFlags: flags
                    timestamp: 0.0f64
                    windowNumber: i64::from(number)
                    context: std::ptr::null_mut::<Object>()
                    characters: string(&typed)
                    charactersIgnoringModifiers: string(&ignoring)
                    isARepeat: NO
                    keyCode: *code
                ];
                anyhow::ensure!(!event.is_null(), "AppKit refused the key {spec}");
                let app: *mut Object = msg_send![class!(NSApplication), sharedApplication];
                let _: () = msg_send![app, postEvent: event atStart: NO];
            }
        }
        log::info!("shot: typed {spec}");
        Ok(())
    }
}

#[cfg(not(target_os = "macos"))]
fn main() {
    eprintln!("shot photographs windows on macOS only");
    std::process::exit(1);
}