//! grep [-i] [-v] [-n] pattern [file...] -- print lines containing
//! `pattern` (plain text, no regular expressions). -i: ignore case,
//! -v: lines that do *not* match, -n: show line numbers.
//! Exit code 0 if something matched, 1 if not, 2 on errors (like grep).
#![no_std]
#![no_main]

extern crate ulib;
ulib::entry!(main);

use ulib::*;

fn contains(line: &[u8], pattern: &[u8], ignore_case: bool) -> bool {
    pattern.is_empty()
        || line.windows(pattern.len()).any(|w| match ignore_case {
            true => w.eq_ignore_ascii_case(pattern),
            false => w == pattern,
        })
}

fn main() -> i64 {
    let (mut ignore_case, mut invert, mut numbers) = (false, false, false);
    let mut i = 1;
    while let Some(a) = arg(i).filter(|a| a.starts_with('-') && a.len() > 1) {
        for flag in a[1..].chars() {
            match flag {
                'i' => ignore_case = true,
                'v' => invert = true,
                'n' => numbers = true,
                _ => {
                    eprintln!("grep: unknown option -{}", flag);
                    return 2;
                }
            }
        }
        i += 1;
    }
    let Some(pattern) = arg(i) else {
        eprintln!("usage: grep [-i] [-v] [-n] pattern [file...]");
        return 2;
    };
    let files = i + 1..argc();
    let many = files.len() > 1;
    let (mut matched, mut status) = (false, 0);
    let mut search = |fd: i64, name: &str| {
        let mut number = 0;
        for_each_line(fd, |line| {
            number += 1;
            if contains(line, pattern.as_bytes(), ignore_case) != invert {
                matched = true;
                if many {
                    print!("{}:", name);
                }
                if numbers {
                    print!("{}:", number);
                }
                write_all(1, line);
                write(1, b"\n");
            }
        })
    };
    if files.is_empty() {
        search(0, "");
    }
    for f in files {
        let name = arg(f).unwrap_or("");
        let fd = open(name, 0);
        let r = if fd < 0 { fd } else { search(fd, name) };
        if fd >= 0 {
            close(fd);
        }
        if r < 0 {
            eprintln!("grep: {}: {}", name, strerror(r));
            status = 2;
        }
    }
    if status != 0 {
        status
    } else if matched {
        0
    } else {
        1
    }
}