// Copyright © SixtyFPS GmbH <info@sixtyfps.io>
// SPDX-License-Identifier: (GPL-3.0-only OR LicenseRef-SixtyFPS-commercial)

#![doc = include_str!("README.md")]

use sixtyfps_interpreter::{ComponentInstance, SharedString, Value};
use std::future::Future;
use std::pin::Pin;
use std::sync::atomic::{AtomicU32, Ordering};
use std::sync::{Arc, Mutex};
use std::task::Wake;
use std::time::Duration;

use clap::Parser;

type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>;

#[derive(Clone, clap::Parser)]
struct Cli {
    #[clap(
        short = 'I',
        name = "include path for other .60 files",
        number_of_values = 1,
        parse(from_os_str)
    )]
    include_paths: Vec<std::path::PathBuf>,

    /// The .60 file to load ('-' for stdin)
    #[clap(name = "path to .60 file", parse(from_os_str))]
    path: std::path::PathBuf,

    /// The style name ('native', 'fluent', or 'ugly')
    #[clap(long, name = "style name")]
    style: Option<String>,

    /// The rendering backend
    #[clap(long, name = "backend")]
    backend: Option<String>,

    /// Automatically watch the file system, and reload when it changes
    #[clap(long)]
    auto_reload: bool,

    /// Load properties from a json file ('-' for stdin)
    #[clap(long, name = "load data file", parse(from_os_str))]
    load_data: Option<std::path::PathBuf>,

    /// Store properties values in a json file at exit ('-' for stdout)
    #[clap(long, name = "save data file", parse(from_os_str))]
    save_data: Option<std::path::PathBuf>,

    /// Specify callbacks handler.
    /// The first argument is the callback name, and the second argument is a string that is going
    /// to be passed to the shell to be executed. Occurences of `$1` will be replaced by the first argument,
    /// and so on.
    #[clap(long, value_names(&["callback", "handler"]), number_of_values = 2)]
    on: Vec<String>,
}

thread_local! {static CURRENT_INSTANCE: std::cell::RefCell<Option<ComponentInstance>> = Default::default();}
static EXIT_CODE: std::sync::atomic::AtomicI32 = std::sync::atomic::AtomicI32::new(0);

fn main() -> Result<()> {
    let args = Cli::parse();

    if args.auto_reload && args.save_data.is_some() {
        eprintln!("Cannot pass both --auto-reload and --save-data");
        std::process::exit(-1);
    }

    if let Some(backend) = &args.backend {
        std::env::set_var("SIXTYFPS_BACKEND", backend);
    }

    let fswatcher = if args.auto_reload { Some(start_fswatch_thread(args.clone())?) } else { None };
    let mut compiler = init_compiler(&args, fswatcher);

    let c = spin_on::spin_on(compiler.build_from_path(args.path));
    sixtyfps_interpreter::print_diagnostics(compiler.diagnostics());

    let c = match c {
        Some(c) => c,
        None => std::process::exit(-1),
    };

    let component = c.create();
    init_dialog(&component);

    if let Some(data_path) = args.load_data {
        load_data(&component, &data_path)?;
    }
    install_callbacks(&component, &args.on);

    if args.auto_reload {
        CURRENT_INSTANCE.with(|current| current.replace(Some(component.clone_strong())));
    }

    component.run();

    if let Some(data_path) = args.save_data {
        let mut obj = serde_json::Map::new();
        for (name, _) in c.properties() {
            fn to_json(val: sixtyfps_interpreter::Value) -> Option<serde_json::Value> {
                match val {
                    sixtyfps_interpreter::Value::Number(x) => Some(x.into()),
                    sixtyfps_interpreter::Value::String(x) => Some(x.as_str().into()),
                    sixtyfps_interpreter::Value::Bool(x) => Some(x.into()),
                    sixtyfps_interpreter::Value::Array(arr) => {
                        let mut res = Vec::with_capacity(arr.len());
                        for x in arr {
                            res.push(to_json(x)?);
                        }
                        Some(serde_json::Value::Array(res))
                    }
                    sixtyfps_interpreter::Value::Struct(st) => {
                        let mut obj = serde_json::Map::new();
                        for (k, v) in st.iter() {
                            obj.insert(k.into(), to_json(v.clone())?);
                        }
                        Some(obj.into())
                    }
                    _ => None,
                }
            }
            if let Some(v) = to_json(component.get_property(&name).unwrap()) {
                obj.insert(name, v);
            }
        }
        if data_path == std::path::Path::new("-") {
            serde_json::to_writer_pretty(std::io::stdout(), &obj)?;
        } else {
            serde_json::to_writer_pretty(std::fs::File::create(data_path)?, &obj)?;
        }
    }

    std::process::exit(EXIT_CODE.load(std::sync::atomic::Ordering::Relaxed))
}

fn init_compiler(
    args: &Cli,
    fswatcher: Option<Arc<Mutex<notify::RecommendedWatcher>>>,
) -> sixtyfps_interpreter::ComponentCompiler {
    let mut compiler = sixtyfps_interpreter::ComponentCompiler::default();
    compiler.set_include_paths(args.include_paths.clone());
    if let Some(style) = &args.style {
        compiler.set_style(style.clone());
    }
    if let Some(watcher) = fswatcher {
        notify::Watcher::watch(
            &mut *watcher.lock().unwrap(),
            &args.path,
            notify::RecursiveMode::NonRecursive,
        )
        .unwrap_or_else(|err| {
            eprintln!("Warning: error while watching {}: {:?}", args.path.display(), err)
        });
        if let Some(data_path) = &args.load_data {
            notify::Watcher::watch(
                &mut *watcher.lock().unwrap(),
                data_path,
                notify::RecursiveMode::NonRecursive,
            )
            .unwrap_or_else(|err| {
                eprintln!("Warning: error while watching {}: {:?}", data_path.display(), err)
            });
        }
        compiler.set_file_loader(move |path| {
            notify::Watcher::watch(
                &mut *watcher.lock().unwrap(),
                &path,
                notify::RecursiveMode::NonRecursive,
            )
            .unwrap_or_else(|err| {
                eprintln!("Warning: error while watching {}: {:?}", path.display(), err)
            });
            Box::pin(async { None })
        })
    }
    compiler
}

fn init_dialog(instance: &ComponentInstance) {
    for cb in instance.definition().callbacks() {
        let exit_code = match cb.as_str() {
            "ok-clicked" | "yes-clicked" | "close-clicked" => 0,
            "cancel-clicked" | "no-clicked" => 1,
            _ => continue,
        };
        // this is a dialog, so clicking the "x" should cancel
        EXIT_CODE.store(1, std::sync::atomic::Ordering::Relaxed);
        instance
            .set_callback(&cb, move |_| {
                EXIT_CODE.store(exit_code, std::sync::atomic::Ordering::Relaxed);
                sixtyfps_rendering_backend_default::backend().quit_event_loop();
                Default::default()
            })
            .unwrap();
    }
}

static PENDING_EVENTS: AtomicU32 = AtomicU32::new(0);

fn start_fswatch_thread(args: Cli) -> Result<Arc<Mutex<notify::RecommendedWatcher>>> {
    let (tx, rx) = std::sync::mpsc::channel();
    let w = Arc::new(Mutex::new(notify::watcher(tx, Duration::from_millis(400))?));
    let w2 = w.clone();
    std::thread::spawn(move || {
        while let Ok(event) = rx.recv() {
            use notify::DebouncedEvent::*;
            if (matches!(event, Write(_) | Remove(_) | Create(_)))
                && PENDING_EVENTS.load(Ordering::SeqCst) == 0
            {
                PENDING_EVENTS.fetch_add(1, Ordering::SeqCst);
                run_in_ui_thread(Box::pin(reload(args.clone(), w2.clone())));
            }
        }
    });
    Ok(w)
}

async fn reload(args: Cli, fswatcher: Arc<Mutex<notify::RecommendedWatcher>>) {
    let mut compiler = init_compiler(&args, Some(fswatcher));
    let c = compiler.build_from_path(&args.path).await;
    sixtyfps_interpreter::print_diagnostics(compiler.diagnostics());

    if let Some(c) = c {
        CURRENT_INSTANCE.with(|current| {
            let mut current = current.borrow_mut();
            if let Some(handle) = current.take() {
                let window = handle.window();
                let new_handle = c.create_with_existing_window(window);
                init_dialog(&new_handle);
                current.replace(new_handle);
            } else {
                let handle = c.create();
                init_dialog(&handle);
                handle.show();
                current.replace(handle);
            }
            if let Some(data_path) = args.load_data {
                let _ = load_data(current.as_ref().unwrap(), &data_path);
            }
            eprintln!("Successful reload of {}", args.path.display());
        });
    }

    PENDING_EVENTS.fetch_sub(1, Ordering::SeqCst);
}

fn load_data(instance: &ComponentInstance, data_path: &std::path::Path) -> Result<()> {
    let json: serde_json::Value = if data_path == std::path::Path::new("-") {
        serde_json::from_reader(std::io::stdin())?
    } else {
        serde_json::from_reader(std::fs::File::open(data_path)?)?
    };

    let obj = json.as_object().ok_or("The data is not a JSON object")?;
    for (name, v) in obj {
        fn from_json(v: &serde_json::Value) -> sixtyfps_interpreter::Value {
            match v {
                serde_json::Value::Null => sixtyfps_interpreter::Value::Void,
                serde_json::Value::Bool(b) => (*b).into(),
                serde_json::Value::Number(n) => {
                    sixtyfps_interpreter::Value::Number(n.as_f64().unwrap_or(f64::NAN))
                }
                serde_json::Value::String(s) => SharedString::from(s.as_str()).into(),
                serde_json::Value::Array(array) => {
                    sixtyfps_interpreter::Value::Array(array.iter().map(from_json).collect())
                }
                serde_json::Value::Object(obj) => obj
                    .iter()
                    .map(|(k, v)| (k.clone(), from_json(v)))
                    .collect::<sixtyfps_interpreter::Struct>()
                    .into(),
            }
        }

        match instance.set_property(name, from_json(v)) {
            Ok(()) => (),
            Err(e) => eprintln!("Warning: cannot set property '{}' from data file: {:?}", name, e),
        };
    }
    Ok(())
}

fn install_callbacks(instance: &ComponentInstance, callbacks: &[String]) {
    assert!(callbacks.len() % 2 == 0);
    for chunk in callbacks.chunks(2) {
        if let [callback, cmd] = chunk {
            let cmd = cmd.clone();
            match instance.set_callback(callback, move |args| {
                match execute_cmd(&cmd, args) {
                    Ok(()) => (),
                    Err(e) => eprintln!("Error: {}", e),
                }
                Value::Void
            }) {
                Ok(()) => (),
                Err(e) => {
                    eprintln!("Warning: cannot set callback handler for '{}': {}", callback, e)
                }
            }
        }
    }
}

fn execute_cmd(cmd: &str, callback_args: &[Value]) -> Result<()> {
    let cmd_args = shlex::split(cmd).ok_or("Could not parse the command string")?;
    let program_name = cmd_args.first().ok_or("Missing program name")?;
    let mut command = std::process::Command::new(program_name);
    let callback_args = callback_args
        .iter()
        .map(|v| {
            Ok(match v {
                Value::Number(x) => x.to_string(),
                Value::String(x) => x.to_string(),
                Value::Bool(x) => x.to_string(),
                Value::Image(img) => {
                    img.path().map(|p| p.to_string_lossy()).unwrap_or_default().into()
                }
                _ => return Err(format!("Cannot convert argument to string: {:?}", v).into()),
            })
        })
        .collect::<Result<Vec<String>>>()?;
    for mut a in cmd_args.into_iter().skip(1) {
        for (idx, cb_a) in callback_args.iter().enumerate() {
            a = a.replace(&format!("${}", idx + 1), cb_a);
        }
        command.arg(a);
    }
    command.spawn()?;
    Ok(())
}

/// This type is duplicated with lsp/preview.rs
struct FutureRunner {
    fut: Mutex<Option<Pin<Box<dyn Future<Output = ()>>>>>,
}

/// Safety: the future is only going to be run in the UI thread
unsafe impl Send for FutureRunner {}
/// Safety: the future is only going to be run in the UI thread
unsafe impl Sync for FutureRunner {}

impl Wake for FutureRunner {
    fn wake(self: Arc<Self>) {
        sixtyfps_rendering_backend_default::backend().post_event(Box::new(move || {
            let waker = self.clone().into();
            let mut cx = std::task::Context::from_waker(&waker);
            let mut fut_opt = self.fut.lock().unwrap();
            if let Some(fut) = &mut *fut_opt {
                match fut.as_mut().poll(&mut cx) {
                    std::task::Poll::Ready(_) => *fut_opt = None,
                    std::task::Poll::Pending => {}
                }
            }
        }));
    }
}

fn run_in_ui_thread(fut: Pin<Box<dyn Future<Output = ()>>>) {
    Arc::new(FutureRunner { fut: Mutex::new(Some(fut)) }).wake()
}