#![crate_name = "uutest"]

/*
 * This file is part of the uutils coreutils package.
 *
 * (c) mahkoh (ju.orth [at] gmail [dot] com)
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

extern crate libc;

use std::collections::HashMap;
use std::os::{args_as_bytes};
use std::str::{from_utf8};

static NAME: &'static str = "test";

// TODO: decide how to handle non-UTF8 input for all the utils
pub fn uumain(_: Vec<String>) -> int {
    let args = args_as_bytes();
    let args: Vec<&[u8]> = args.iter().map(|a| a.as_slice()).collect();
    if args.len() == 0 {
        return 2;
    }
    let args =
        if !args[0].ends_with(NAME.as_bytes()) {
            args.slice_from(1)
        } else {
            args.as_slice()
        };
    let args = match args[0] {
        b"[" => match args[args.len() - 1] {
            b"]" => args.slice(1, args.len() - 1),
            _ => return 2,
        },
        _ => args.slice(1, args.len()),
    };
    let mut error = false;
    let retval = 1 - parse_expr(args, &mut error) as int;
    if error {
        2
    } else {
        retval
    }
}

fn one(args: &[&[u8]]) -> bool {
    args[0].len() > 0
}

fn two(args: &[&[u8]], error: &mut bool) -> bool {
    match args[0] {
        b"!" => !one(args.slice_from(1)),
        b"-b" => path(args[1], BlockSpecial),
        b"-c" => path(args[1], CharacterSpecial),
        b"-d" => path(args[1], Directory),
        b"-e" => path(args[1], Exists),
        b"-f" => path(args[1], Regular),
        b"-g" => path(args[1], GroupIDFlag),
        b"-h" => path(args[1], SymLink),
        b"-L" => path(args[1], SymLink),
        b"-n" => one(args.slice_from(1)),
        b"-p" => path(args[1], FIFO),
        b"-r" => path(args[1], Readable),
        b"-S" => path(args[1], Socket),
        b"-s" => path(args[1], NonEmpty),
        b"-t" => isatty(args[1]),
        b"-u" => path(args[1], UserIDFlag),
        b"-w" => path(args[1], Writable),
        b"-x" => path(args[1], Executable),
        b"-z" => !one(args.slice_from(1)),
        _ => {
            *error = true;
            false
        }
    }
}

fn three(args: &[&[u8]], error: &mut bool) -> bool {
    match args[1] {
        b"=" => args[0] == args[2],
        b"!=" => args[0] != args[2],
        b"-eq" => integers(args[0], args[2], Equal),
        b"-ne" => integers(args[0], args[2], Unequal),
        b"-gt" => integers(args[0], args[2], Greater),
        b"-ge" => integers(args[0], args[2], GreaterEqual),
        b"-lt" => integers(args[0], args[2], Less),
        b"-le" => integers(args[0], args[2], LessEqual),
        _ => match args[0] {
            b"!" => !two(args.slice_from(1), error),
            _ => {
                *error = true;
                false
            }
        }
    }
}

fn four(args: &[&[u8]], error: &mut bool) -> bool {
    match args[0] {
        b"!" => {
            !three(args.slice_from(1), error)
        }
        _ => {
            *error = true;
            false
        }
    }
}

enum IntegerCondition {
    Equal,
    Unequal,
    Greater,
    GreaterEqual,
    Less,
    LessEqual,
}

fn integers(a: &[u8], b: &[u8], cond: IntegerCondition) -> bool {
    let (a, b): (&str, &str) = match (from_utf8(a), from_utf8(b)) {
        (Some(a), Some(b)) => (a, b),
        _ => return false,
    };
    let (a, b): (i64, i64) = match (from_str(a), from_str(b)) {
        (Some(a), Some(b)) => (a, b),
        _ => return false,
    };
    match cond {
        Equal        => a == b,
        Unequal      => a != b,
        Greater      => a >  b,
        GreaterEqual => a >= b,
        Less         => a <  b,
        LessEqual    => a <= b,
    }
}

fn isatty(fd: &[u8]) -> bool {
    use libc::{isatty};
    from_utf8(fd).and_then(|s| from_str(s))
            .map(|i| unsafe { isatty(i) == 1 }).unwrap_or(false)
}

fn dispatch(args: &mut &[&[u8]], error: &mut bool) -> bool {
    let (val, idx) = match args.len() {
        0 => {
            *error = true;
            (false, 0)
        }
        1 => (one(*args), 1),
        2 => dispatch_two(args, error),
        3 => dispatch_three(args, error),
        _ => dispatch_four(args, error)
    };
    *args = (*args).slice_from(idx);
    val
}

fn dispatch_two(args: &mut &[&[u8]], error: &mut bool) -> (bool, uint) {
    let val = two(*args, error);
    if *error {
        *error = false;
        (one(*args), 1)
    } else {
        (val, 2)
    }
}

fn dispatch_three(args: &mut &[&[u8]], error: &mut bool) -> (bool, uint) {
    let val = three(*args, error);
    if *error {
        *error = false;
        dispatch_two(args, error)
    } else {
        (val, 3)
    }
}

fn dispatch_four(args: &mut &[&[u8]], error: &mut bool) -> (bool, uint) {
    let val = four(*args, error);
    if *error {
        *error = false;
        dispatch_three(args, error)
    } else {
        (val, 4)
    }
}

enum Precedence {
    Unknown = 0,
    Paren,     // FIXME: this is useless (parentheses have not been implemented)
    Or,
    And,
    BUnOp,
    BinOp,
    UnOp
}

fn parse_expr(mut args: &[&[u8]], error: &mut bool) -> bool {
    if args.len() == 0 {
        false
    } else {
        let hashmap = setup_hashmap();
        let lhs = dispatch(&mut args, error);

        if args.len() > 0 {
            parse_expr_helper(&hashmap, &mut args, lhs, Unknown, error)
        } else {
            lhs
        }
    }
}

fn parse_expr_helper<'a>(hashmap: &HashMap<&'a [u8], Precedence>,
                         args: &mut &[&'a [u8]],
                         mut lhs: bool,
                         min_prec: Precedence,
                         error: &mut bool) -> bool {
    let mut prec = *hashmap.get(&args[0]).unwrap_or_else(|| {
        *error = true;
        &min_prec
    });
    while !*error && args.len() > 0 && prec as uint >= min_prec as uint {
        let op = args[0];
        *args = (*args).slice_from(1);
        let mut rhs = dispatch(args, error);
        while args.len() > 0 {
            let subprec = *hashmap.get(&args[0]).unwrap_or_else(|| {
                *error = true;
                &min_prec
            });
            if subprec as uint <= prec as uint || *error {
                break;
            }
            rhs = parse_expr_helper(hashmap, args, rhs, subprec, error);
        }
        lhs = match prec {
            UnOp | BUnOp => {
                *error = true;
                false
            }
            And => lhs && rhs,
            Or => lhs || rhs,
            BinOp => three(&[if lhs { b" " } else { b"" }, op, if rhs { b" " } else { b"" }], error),
            Paren => unimplemented!(),  // TODO: implement parentheses
            _ => unreachable!()
        };
        if args.len() > 0 {
            prec = *hashmap.get(&args[0]).unwrap_or_else(|| {
                *error = true;
                &min_prec
            });
        }
    }
    lhs
}

#[inline]
fn setup_hashmap<'a>() -> HashMap<&'a [u8], Precedence> {
    let mut hashmap = HashMap::<&'a [u8], Precedence>::new();

    hashmap.insert(b"-b", UnOp);
    hashmap.insert(b"-c", UnOp);
    hashmap.insert(b"-d", UnOp);
    hashmap.insert(b"-e", UnOp);
    hashmap.insert(b"-f", UnOp);
    hashmap.insert(b"-g", UnOp);
    hashmap.insert(b"-h", UnOp);
    hashmap.insert(b"-L", UnOp);
    hashmap.insert(b"-n", UnOp);
    hashmap.insert(b"-p", UnOp);
    hashmap.insert(b"-r", UnOp);
    hashmap.insert(b"-S", UnOp);
    hashmap.insert(b"-s", UnOp);
    hashmap.insert(b"-t", UnOp);
    hashmap.insert(b"-u", UnOp);
    hashmap.insert(b"-w", UnOp);
    hashmap.insert(b"-x", UnOp);
    hashmap.insert(b"-z", UnOp);

    hashmap.insert(b"=", BinOp);
    hashmap.insert(b"!=", BinOp);
    hashmap.insert(b"-eq", BinOp);
    hashmap.insert(b"-ne", BinOp);
    hashmap.insert(b"-gt", BinOp);
    hashmap.insert(b"-ge", BinOp);
    hashmap.insert(b"-lt", BinOp);
    hashmap.insert(b"-le", BinOp);

    hashmap.insert(b"!", BUnOp);

    hashmap.insert(b"-a", And);
    hashmap.insert(b"-o", Or);

    hashmap.insert(b"(", Paren);
    hashmap.insert(b")", Paren);

    hashmap
}

#[deriving(Eq, PartialEq)]
enum PathCondition {
    BlockSpecial,
    CharacterSpecial,
    Directory,
    Exists,
    Regular,
    GroupIDFlag,
    SymLink,
    FIFO,
    Readable,
    Socket,
    NonEmpty,
    UserIDFlag,
    Writable,
    Executable,
}

#[cfg(not(windows))]
fn path(path: &[u8], cond: PathCondition) -> bool {
    use libc::{stat, lstat, S_IFMT, S_IFLNK, S_IFBLK, S_IFCHR, S_IFDIR, S_IFREG};
    use libc::{S_IFIFO, mode_t};
    static S_ISUID: mode_t = 0o4000;
    static S_ISGID: mode_t = 0o2000;
    static S_IFSOCK: mode_t = 0o140000;

    enum Permission {
        Read    = 0o4,
        Write   = 0o2,
        Execute = 0o1,
    }
    let perm = |stat: stat, p: Permission| {
        use libc::{getgid, getuid};
        let (uid, gid) = unsafe { (getuid(), getgid()) };
        if uid == stat.st_uid {
            stat.st_mode & (p as mode_t << 6) != 0
        } else if gid == stat.st_gid {
            stat.st_mode & (p as mode_t << 3) != 0
        } else {
            stat.st_mode & (p as mode_t << 0) != 0
        }
    };

    let path = unsafe { path.to_c_str_unchecked() };
    let mut stat = unsafe { std::mem::zeroed() };
    if cond == SymLink {
        if unsafe { lstat(path.as_ptr(), &mut stat) } == 0 {
            if stat.st_mode & S_IFMT == S_IFLNK {
                return true;
            }
        }
        return false;
    }
    if unsafe { libc::stat(path.as_ptr(), &mut stat) } != 0 {
        return false;
    }
    let file_type = stat.st_mode & S_IFMT;
    match cond {
        BlockSpecial     => file_type == S_IFBLK,
        CharacterSpecial => file_type == S_IFCHR,
        Directory        => file_type == S_IFDIR,
        Exists           => true,
        Regular          => file_type == S_IFREG,
        GroupIDFlag      => stat.st_mode & S_ISGID != 0,
        SymLink          => true,
        FIFO             => file_type == S_IFIFO,
        Readable         => perm(stat, Read),
        Socket           => file_type == S_IFSOCK,
        NonEmpty         => stat.st_size > 0,
        UserIDFlag       => stat.st_mode & S_ISUID != 0,
        Writable         => perm(stat, Write),
        Executable       => perm(stat, Execute),
    }
}

#[cfg(windows)]
fn path(path: &[u8], cond: PathCondition) -> bool {
    use std::io::{TypeFile, TypeDirectory, TypeBlockSpecial, TypeNamedPipe};
    use std::io::fs::{stat};
    use std::path::{Path};

    let path = match Path::new_opt(path) {
        Some(p) => p,
        None => return false,
    };
    let stat = match stat(&path) {
        Ok(s) => s,
        _ => return false,
    };
    match cond {
        BlockSpecial     => stat.kind == TypeBlockSpecial,
        CharacterSpecial => false,
        Directory        => stat.kind == TypeDirectory,
        Exists           => true,
        Regular          => stat.kind == TypeFile,
        GroupIDFlag      => false,
        SymLink          => false,
        FIFO             => stat.kind == TypeNamedPipe,
        Readable         => false, // TODO
        Socket           => false, // TODO?
        NonEmpty         => stat.size > 0,
        UserIDFlag       => false,
        Writable         => false, // TODO
        Executable       => false, // TODO
    }
}