// Copyright (C) 2020 "Maxime “pep” Buquet <pep@bouah.net>"
//
// This program is free software: you can redistribute it and/or modify it
// under the terms of the GNU Affero General Public License as published by the
// Free Software Foundation, either version 3 of the License, or (at your
// option) any later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License
// for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.

use std::convert::TryFrom;
use std::fs;
use std::path::PathBuf;

use pkstrings::PKString;
use structopt::StructOpt;

#[derive(Debug, StructOpt)]
#[structopt(name = "strings", about = "Display printable strings in [file(s)]")]
struct Opt {
    #[structopt(parse(from_os_str), long, short)]
    files: Vec<PathBuf>,
}

fn print_buffer(offset: usize, buffer: &String) {
    let trimmed = buffer.trim_matches('_');
    if trimmed.len() > 0 {
        println!("{:#7x}: {}", offset, buffer);
    }
}

fn read_data(data: Vec<u8>) {
    let mut buffer = String::new();
    let mut last_offset_start: usize = 0;
    let eos: &[u8] = &[0x50, 0x57, 0x58, 0x5f];  // end of string
    let mut last_pkstr: PKString = PKString::try_from(&[0x00][..]).unwrap();

    for (offset, ord) in data.iter().enumerate() {
        // Read current chr
        match PKString::try_from(&[*ord][..]) {
            Err(_) => {
                if buffer.len() >= 4 {
                    print_buffer(last_offset_start, &buffer);
                }
                buffer.clear();
                last_offset_start = offset + 1;
            },
            Ok(pkstr) => {
                if buffer.len() == 0 {
                    buffer.push_str(String::from(&pkstr).as_str());
                    last_pkstr = pkstr;
                } else {
                    let ord = &pkstr.as_slice()[0];
                    let last_ord: u8 = {
                        let tmp = Vec::<u8>::from(last_pkstr.clone());
                        tmp[tmp.len() - 1]
                    };

                    if ! eos.contains(ord) && eos.contains(&last_ord) && buffer.len() >= 4 {
                        print_buffer(last_offset_start, &buffer);
                        buffer.clear();
                        last_offset_start = offset;
                    }

                    buffer.push_str(String::from(&pkstr).as_str());

                    if buffer.len() > 1 && eos.contains(ord) && eos.contains(&last_ord) && buffer.len() >= 4 {
                        print_buffer(last_offset_start, &buffer);
                        buffer.clear();
                        last_offset_start = offset + 1;
                    }

                    last_pkstr = pkstr;
                }
            },
        }
    }

    // Print off any remaining buffer
    if buffer.len() > 0 {
        print_buffer(last_offset_start, &buffer);
    }
}

fn main() {
    let opt = Opt::from_args();

    for file in opt.files {
        let data: Vec<u8> = fs::read(file).unwrap();
        read_data(data)
    }
}