use std::{error::Error, ffi::OsStr, fs, path::PathBuf, process::{self, Command}};

use css_minify::optimizations::{Minifier, Level};

fn asset_path(asset: &PathBuf) -> PathBuf {
    let mut path = asset.components().take(1).collect::<PathBuf>();
    path.push(asset.components().last().unwrap());
    path
}

fn template_path(template: &PathBuf) -> PathBuf {
    let mut path = template.components().take(template.components().count() - 2).collect::<PathBuf>();
    path.push(template.components().last().unwrap());
    path
}

fn extfilter(valid: String, x: Option<&OsStr>) -> bool {
    if x.is_none() {
        return false
    }
    let ext = x.clone().unwrap().to_str().unwrap().to_string();
    ext == valid
}

fn system(cmd: &str, args: &[&str]) -> Result<String, Box<dyn Error>> {
    let out = Command::new(cmd)
        .args(args)
        .output()
        ?;

    if out.stderr.len() != 0 {
        panic!("Got this while running {cmd} with \"{}\": {}", args.join(" "), String::from_utf8(out.stderr).unwrap())
    }

    Ok(String::from_utf8(out.stdout)?)
}

fn check_cmd<T: AsRef<OsStr>>(cmd: T) -> bool {
    Command::new(cmd)
        .spawn()
        .is_ok()
}

fn main() {

    let html_exists = check_cmd("html-minifier");
    let ugjs_exists = check_cmd("uglify-js");

    if ! (html_exists || ugjs_exists) {
        eprintln!("html-minifier or uglify-js are not installed! Trying to install them via npm...");
        if ! check_cmd("npm") {
            eprintln!("npm is not installed! Please install npm and/or html-minifier and uglify-js and build again");
            process::exit(1)
        }

        let mut cmd = Command::new("npm");
        cmd.arg("install")
            .arg("--global");

        if ! html_exists {
            cmd.arg("html-minifier");
        }
        if ! ugjs_exists {
            cmd.arg("uglify-js");
        }

        let res = cmd.spawn().unwrap().wait().unwrap();
        if res.success() {
            eprintln!("Successfully installed html-minifier and/or uglify-js");
        } else {
            eprintln!("Couldn't install html-minifier and/or uglify-js! Check the log above for details.");
            process::exit(1)
        }
    }

    println!("cargo:rerun-if-changed=static/assets");
    println!("cargo:rerun-if-changed=templates/source");

    let assets = fs::read_dir("static/assets").unwrap();
    let assets = assets
        .map(|x| x.unwrap().path())
        .filter(|x| x.extension().is_some())
        .collect::<Vec<PathBuf>>();
    
    let styles = assets
        .iter()
        .filter(|x| {
            extfilter("css".into(), x.extension())
        })
        .collect::<Vec<&PathBuf>>();

    let scripts = assets
        .iter()
        .filter(|x| {
            extfilter("js".into(), x.extension())
        })
        .collect::<Vec<&PathBuf>>();

    styles.iter().for_each(|asset| {
        let bundled = Minifier::default().minify(
            String::from_utf8(fs::read(asset).unwrap()).unwrap().as_str(),
            Level::Zero
        ).unwrap();
        
        fs::write(asset_path(asset), bundled).unwrap();
    });

    scripts.iter().for_each(|asset| {
        Command::new("uglifyjs")
            .arg(asset)
            .arg("-o")
            .arg(asset_path(asset))
            .arg("-c")
            .spawn()
            .unwrap();
    });

    // precompile templates
    let templates = fs::read_dir("templates/source").unwrap();
    let templates = templates
        .map(|x| x.unwrap().path().canonicalize().unwrap())
        .filter(|x| extfilter("html".into(), x.extension()))
        .collect::<Vec<PathBuf>>();
    
    templates.iter().for_each(|template| {
        Command::new("html-minifier")
            .arg(template.canonicalize().unwrap())
            .arg("--collapse-whitespace")
            // .arg("--minify-js")
            // .arg("--minify-css")
            // .arg("--keep-closing-slash")
            .arg("--output")
            .arg(template_path(template))
            .spawn()
            .unwrap();
        
    });

    let commit = system("git", &["rev-parse", "HEAD"]).map_err(|x| x.to_string());
    let branch = system("git", &["rev-parse", "--abbrev-ref", "HEAD"]).map_err(|x| x.to_string());

    match commit {
        Err(err) => panic!("Can't get commit: {}", err),
        Ok(commit) => println!("cargo:rustc-env=COMMIT_HASH={commit}")
    }

    match branch {
        Err(err) => panic!("Can't get commit: {}", err),
        Ok(branch) => println!("cargo:rustc-env=COMMIT_BRANCH={branch}")
    }
}