#!/usr/bin/env rust-script
//!
//! ```cargo
//! [dependencies]
//! serde = { version = "1.0", features = ["derive"] }
//! serde_json = "1.0"
//! anyhow = "1.0"
//! handlebars = "3"
//! log = "0.4"
//! env_logger = "0.10"
//! tokio = { version = "1", features = ["full"] }
//! ```

use anyhow::Result;
use handlebars::Handlebars;
use serde::Deserialize;
use std::collections::HashMap;
use std::process::Command;
use std::{fs, io};
use log::{info, debug};

#[derive(Deserialize, Debug)]
struct Monitor {
    id: u32,
    name: String,
    width: u32,
    height: u32,
}

impl Monitor {
    fn list() -> Result<Vec<Self>> {
        let output = Command::new("hyprctl").arg("monitors").arg("-j").output()?;

        assert!(output.status.success());

        let monitors_json = std::str::from_utf8(&output.stdout)?;

        Ok(serde_json::from_str(monitors_json)?)
    }

    fn launch_bar(&self, wl_display: &str, home: &str) -> Result<()> {
        let bar_name = format!("bar-{wl_display}-{}", self.id);
        let dir = format!("/tmp/vbar/{wl_display}/{}", self.id);

        info!("Launching bar {bar_name}");

        match fs::create_dir_all(&dir) {
            Ok(()) => {}
            Err(e) if e.kind() == io::ErrorKind::AlreadyExists => {
                info!("Directory {dir} already exists. Recreating...");
                let output = Command::new("rm").arg("-rf").arg(&dir).output()?;
                assert!(output.status.success());

                fs::create_dir_all(&dir)?;
            }
            Err(e) => return Err(e.into()),
        }

        self.generate_bar_config(
            &bar_name,
            &home,
            &dir,
            &format!("{home}/.config/eww/templates/bar"),
            &dir,
        )?;

        Command::new("eww")
            .arg("-c")
            .arg(&dir)
            .arg("open")
            .arg("--restart")
            .arg(&bar_name)
            .spawn()?;

        info!("Successfuly launched bar {bar_name}");

        Ok(())
    }

    fn generate_bar_config(
        &self,
        bar_name: &str,
        home: &str,
        base_dir: &str,
        source_dir: &str,
        dest_dir: &str,
    ) -> Result<()> {
        for entry in fs::read_dir(source_dir)? {
            let entry = entry?;
            let path = entry.path();
            let relpath = path.strip_prefix(&source_dir)?.to_str().unwrap();

            if path.is_dir() {
                fs::create_dir_all(&format!("{dest_dir}/{relpath}"))?;

                self.generate_bar_config(
                    &bar_name,
                    &home,
                    &base_dir,
                    &path.to_str().unwrap(),
                    &format!("{dest_dir}/{relpath}"),
                )?;
            } else if path.is_file() {
                let data = fs::read_to_string(&path)?;
                let output = self.template(&data, &bar_name, &home, &base_dir)?;

                fs::write(format!("{dest_dir}/{relpath}"), output)?;
            }
        }

        Ok(())
    }

    fn template(&self, source: &str, bar_name: &str, home: &str, base_dir: &str) -> Result<String> {
        let height: u32 = (self.height as f32 * 0.02) as u32;
        let id_str = self.id.to_string();
        let height_str = height.to_string();

        let values: HashMap<&str, &str> = HashMap::from([
            ("monitor", id_str.as_str()),
            ("monitor_name", self.name.as_str()),
            ("bar_name", bar_name),
            ("home", home),
            ("base_dir", base_dir),
            ("height", height_str.as_str()),
        ]);

        let mut handlebars = Handlebars::new();
        handlebars.register_template_string("tpl", source)?;
        Ok(handlebars.render("tpl", &values)?)
    }
}

#[tokio::main]
async fn main() -> Result<()> {
    env_logger::init();
    info!("Starting...");
    let wl_display = std::env::var_os("WAYLAND_DISPLAY")
        .unwrap()
        .into_string()
        .unwrap();

    let home = std::env::var_os("HOME").unwrap().into_string().unwrap();

    let monitors = Monitor::list()?;
    info!("Received monitor list");
    debug!("{:?}", monitors);

    let mut handles = Vec::new();

    for monitor in monitors {
        let home = home.clone();
        let wl_display = wl_display.clone();
        let handle = tokio::spawn(async move {
            monitor.launch_bar(&wl_display, &home).unwrap();
        });
        handles.push(handle);
    }

    for handle in handles {
        handle.await?;
    }

    Ok(())
}