//! Copyright (C) 2022, Dmitriy Pleshevskiy <dmitriy@pleshevski.ru>
//!
//! vnetod is free software: you can redistribute it and/or modify
//! it under the terms of the GNU General Public License as published by
//! the Free Software Foundation, either version 3 of the License, or
//! (at your option) any later version.
//!
//! vnetod 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 General Public License for more details.
//!
//! You should have received a copy of the GNU General Public License
//! along with vnetod.  If not, see <https://www.gnu.org/licenses/>.
//!

#[cfg(feature = "color")]
use termcolor::{Color, ColorChoice, ColorSpec, StandardStream, WriteColor};

use crate::{cli::Args, domain};
use std::fs::File;
use std::io::Write;

#[derive(Debug)]
pub enum Error {
    OpenFile,
    WriteFile,
}

impl std::fmt::Display for Error {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Error::OpenFile => f.write_str("Cannot open file"),
            Error::WriteFile => f.write_str("Cannot write file"),
        }
    }
}

impl std::error::Error for Error {}

pub fn execute(args: &Args) -> Result<(), Error> {
    let content = std::fs::read_to_string(&args.file).map_err(|_| Error::OpenFile)?;

    let fs_writer = (!args.dry_run)
        .then(|| {
            File::create(args.output.as_ref().unwrap_or(&args.file)).map_err(|_| Error::OpenFile)
        })
        .transpose()?;

    let new_content = domain::switch::execute(domain::switch::Request {
        content: &content,
        sections: &args.sections,
        on_line: Some(Box::new(print_line)),
    });
    if let Some(mut fs_writer) = fs_writer {
        fs_writer
            .write_all(new_content.as_bytes())
            .map_err(|_| Error::WriteFile)?;
    }

    Ok(())
}

#[cfg(feature = "color")]
fn print_line(line: &String) {
    let mut stdout = StandardStream::stdout(ColorChoice::Always);
    let color = line
        .starts_with("###")
        .then_some(Color::Yellow)
        .or_else(|| (!line.starts_with("#")).then_some(Color::Green));
    stdout.set_color(ColorSpec::new().set_fg(color)).ok();
    write!(&mut stdout, "{}", line).unwrap();
    stdout.reset().ok();
}

#[cfg(not(feature = "color"))]
fn print_line(line: &String) {
    print!("{}", line)
}