use std::env::{args, var};
use std::fs;
use std::io::Cursor;
use std::path::{Path, PathBuf};
use std::process::exit;
use std::sync::mpsc;
use std::sync::mpsc::TryRecvError;
use std::thread::sleep;
use std::time::Duration;
use colored::Colorize;
use notify::{Event, EventKind, RecursiveMode, Watcher};
use tiny_http::{Response, Server, StatusCode};
use wasm_pack::command::build::{BuildOptions, Target};
use wasm_pack::command::run_wasm_pack;
use wasm_pack::progressbar::LogLevel;

fn workspace_dir() -> PathBuf {
    let output = std::process::Command::new(env!("CARGO"))
        .arg("locate-project")
        .arg("--workspace")
        .arg("--message-format=plain")
        .output()
        .unwrap()
        .stdout;
    let cargo_path = Path::new(std::str::from_utf8(&output).unwrap().trim());
    cargo_path.parent().unwrap().to_path_buf()
}

fn build_client() -> anyhow::Result<()> {
    let cli = wasm_pack::Cli {
        cmd: wasm_pack::command::Command::Build(BuildOptions {
            path: Some(workspace_dir().join("crates/client")),
            scope: None,
            mode: Default::default(),
            disable_dts: false,
            weak_refs: false,
            reference_types: false,
            target: Target::Web,
            debug: false,
            dev: false,
            release: false,
            profiling: false,
            out_dir: "pkg".to_string(),
            out_name: None,
            no_pack: false,
            no_opt: true,
            extra_options: vec![],
        }),
        verbosity: 0,
        quiet: true,
        log_level: LogLevel::Error,
    };
    run_wasm_pack(cli.cmd)
}

fn try_build_client() -> bool {
    match build_client() {
        Ok(_) => {
            println!("{} -- Client package built successfully", "✓ Success".green().bold());
            true
        },
        Err(e) => {
            eprintln!("{} -- Client package failed to build: {}", "✗ Failed".red().bold(), e);
            false
        }
    }
}

fn start_server() {
    let bind = var("BIND").unwrap_or("[::]:8000".to_string());
    let server = Server::http(&bind).unwrap();
    println!("{} on {bind}", "✓ Listening".magenta().bold());
    for req in server.incoming_requests() {
        let mut path = Path::new(req.url());
        if path == Path::new("/") {
            path = Path::new("/index.html");
        }
        
        let path = path.strip_prefix(Path::new("/")).unwrap();
        
        let full_path = workspace_dir().join("crates/client").join(path);
        
        let content = match fs::read(full_path.clone()) {
            Ok(r) => r,
            Err(_) => {
                let _ = req.respond(Response::new(StatusCode::from(404), vec![], Cursor::new(vec![]), None, None));
                continue;
            }
        };

        let len = content.len();

        let header = tiny_http::Header::from_bytes(
            &b"Content-Type"[..],
            if full_path.to_str().unwrap().ends_with(".html") {
                &b"text/html"[..]
            } else if full_path.to_str().unwrap().ends_with(".js") {
                &b"text/javascript"[..]
            } else if full_path.to_str().unwrap().ends_with(".wasm") {
                &b"application/wasm"[..]
            } else {
                &b"application/octet-stream"[..]
            }
        ).unwrap();
        
        let response = Response::new(
            StatusCode::from(200),
            vec![
                header
            ],
            Cursor::new(content),
            Some(len),
            None
        );
        let _ = req.respond(response);
    }
}

fn main() {
    let mut args = args();
    let subcommand = args.nth(1).unwrap();

    match subcommand.as_str() {
        "client" => {
            if !try_build_client() {
                exit(1);
            }
        },
        "watch" | "serve" => {
            let serve = subcommand == "serve";

            if serve {
                std::thread::spawn(start_server);
            }

            try_build_client();
            let (tx, rx) = mpsc::channel::<notify::Result<Event>>();

            // Use recommended_watcher() to automatically select the best implementation
            // for your platform. The `EventHandler` passed to this constructor can be a
            // closure, a `std::sync::mpsc::Sender`, a `crossbeam_channel::Sender`, or
            // another type the trait is implemented for.
            let mut watcher = notify::recommended_watcher(tx).unwrap();

            // Add a path to be watched. All files and directories at that path and
            // below will be monitored for changes.
            watcher.watch(&workspace_dir().join("crates"), RecursiveMode::Recursive).unwrap();
            println!("{}", "[Watch] 🛈 Watching for file changes".blue().bold());
            // Block forever, printing out events as they come in

            let mut needs_rebuild = false;

            loop {
                let res = rx.try_recv();

                let res = match res {
                    Ok(r) => r,
                    Err(TryRecvError::Empty) => {
                        if needs_rebuild {
                            // wait 1s then check again, then rebuild
                            sleep(Duration::from_secs(1));
                            if let Ok(r) = rx.try_recv() {
                                r
                            } else {
                                try_build_client();
                                needs_rebuild = false;

                                rx.recv().unwrap()
                            }
                        } else {
                            rx.recv().unwrap()
                        }
                    },
                    Err(TryRecvError::Disconnected) => panic!("{:?}", TryRecvError::Disconnected)
                };

                match res {
                    Ok(event) => {
                        if let EventKind::Modify(_) = event.kind {
                            let has_non_generated_update = false;
                            for path in &event.paths {
                                if !path.to_str().unwrap().contains("client/pkg") && !path.to_str().unwrap().ends_with("~") {
                                    needs_rebuild = true;
                                }
                            }
                        }

                    },
                    Err(e) => {
                        eprintln!("{} -- Error watching for files: {}", "[Watch] ✗ Error".red().bold(), e);
                    },
                }
            }
        },
        _ => panic!("unsupported command")
    }
}