#![crate_id = "relpath#1.0.0"]

/*
 * This file is part of the uutils coreutils package.
 *
 * (c) 2014 Vsevolod Velichko <torkvemada@sorokdva.net>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

#![feature(macro_rules)]
extern crate getopts;
extern crate libc;

use getopts::{optflag, optopt, getopts, usage};

#[path = "../common/util.rs"] mod util;

static NAME: &'static str = "relpath";
static VERSION: &'static str = "1.0.0";

pub fn uumain(args: Vec<String>) -> int {
    let program = args.get(0);
    let options = [
        optflag("h", "help", "Show help and exit"),
        optflag("V", "version", "Show version and exit"),
        optopt("d", "", "If any of FROM and TO is not subpath of DIR, output absolute path instead of relative", "DIR"),
    ];

    let opts = match getopts(args.tail(), options) {
        Ok(m) => m,
        Err(f) => {
            show_error!("{}", f);
            show_usage(program.as_slice(), options);
            return 1
        }
    };

    if opts.opt_present("V") { version(); return 0 }
    if opts.opt_present("h") { show_usage(program.as_slice(), options); return 0 }

    if opts.free.len() == 0 {
        show_error!("Missing operand: TO");
        println!("Try `{:s} --help` for more information.", program.as_slice());
        return 1
    }

    let to = Path::new(opts.free.get(0).as_slice());
    let from = if opts.free.len() > 1 {
        Path::new(opts.free.get(1).as_slice())
    } else {
        std::os::getcwd()
    };
    let absto = std::os::make_absolute(&to);
    let absfrom = std::os::make_absolute(&from);

    if opts.opt_present("d") {
        let base = Path::new(opts.opt_str("d").unwrap());
        let absbase = std::os::make_absolute(&base);
        if !absbase.is_ancestor_of(&absto) || !absbase.is_ancestor_of(&absfrom) {
            println!("{}", absto.display());
            return 0
        }
    }

    let mut suffixPos = 0;
    absfrom.components()
        .zip(absto.components())
        .take_while(
            |&(f, t)| if f == t {
                suffixPos += 1; true
            } else {
                false
            }).last();

    let mut result = Path::new("");
    absfrom.components().skip(suffixPos).map(|_| result.push("..")).last();
    absto.components().skip(suffixPos).map(|x| result.push(x)).last();

    println!("{}", result.display());
    0
}

fn version() {
    println!("{} v{}", NAME, VERSION)
}

fn show_usage(program: &str, options: &[getopts::OptGroup]) {
    version();
    println!("Usage:");
    println!("  {:s} [-d DIR] TO [FROM]", program);
    println!("  {:s} -V|--version", program);
    println!("  {:s} -h|--help", program);
    println!("");
    print!("{:s}", usage(
            "Convert TO destination to the relative path from the FROM dir.\n\
            If FROM path is omitted, current working dir will be used.", options)
    );
}