//! wave-deinter.rs
//! (c) 2021 Jamie Hardt. All rights reserved.
//!
//! This program demonstrates splitting a multichannel file into separate monophonic files for each
//! individual channel.

use std::io;
use std::path::Path;

extern crate bwavfile;
use bwavfile::{ChannelDescriptor, ChannelMask, Error, WaveFmt, WaveReader, WaveWriter};

#[macro_use]
extern crate clap;
use clap::{App, Arg};

fn name_suffix(
    force_numeric: bool,
    delim: &str,
    index: usize,
    channel_descriptor: &ChannelDescriptor,
) -> String {
    if force_numeric || channel_descriptor.speaker == ChannelMask::DirectOut {
        format!("{}A{:02}", delim, index)
    } else {
        let chan_name = match channel_descriptor.speaker {
            ChannelMask::FrontLeft => "L",
            ChannelMask::FrontCenter => "C",
            ChannelMask::FrontRight => "R",
            ChannelMask::BackLeft => "Ls",
            ChannelMask::BackRight => "Rs",
            ChannelMask::BackCenter => "S",
            ChannelMask::TopCenter => "Tc",
            ChannelMask::LowFrequency => "Lfe",
            ChannelMask::SideLeft => "Lss",
            ChannelMask::SideRight => "Rss",
            ChannelMask::FrontCenterLeft => "Lc",
            ChannelMask::FrontCenterRight => "Rc",
            ChannelMask::TopFrontLeft => "Ltf",
            ChannelMask::TopFrontCenter => "Ctf",
            ChannelMask::TopFrontRight => "Rtf",
            ChannelMask::TopBackLeft => "Ltb",
            ChannelMask::TopBackCenter => "Ctb",
            ChannelMask::TopBackRight => "Rtb",
            ChannelMask::DirectOut => panic!("Error, can't get here"),
        };
        format!("{}{}", delim, chan_name)
    }
}

fn process_file(infile: &str, delim: &str, numeric_channel_names: bool) -> Result<(), Error> {
    let mut input_file = WaveReader::open(infile)?;
    let channel_desc = input_file.channels()?;
    let input_format = input_file.format()?;

    if channel_desc.len() == 1 {
        println!("Input file in monoaural, exiting.");
        return Ok(());
    }

    let infile_path = Path::new(infile);
    let basename = infile_path
        .file_stem()
        .expect("Unable to extract file basename")
        .to_str()
        .unwrap();
    let output_dir = infile_path
        .parent()
        .expect("Unable to derive parent directory");

    let ouptut_format =
        WaveFmt::new_pcm_mono(input_format.sample_rate, input_format.bits_per_sample);
    let mut input_wave_reader = input_file.audio_frame_reader()?;
    let mut output_wave_writers = channel_desc
        .iter()
        .enumerate()
        .map(|(n, channel)| {
            let suffix = name_suffix(numeric_channel_names, delim, n + 1, channel);
            let outfile_name = output_dir
                .join(format!("{}{}.wav", basename, suffix))
                .into_os_string()
                .into_string()
                .unwrap();

            WaveWriter::create(&outfile_name, ouptut_format)
                .expect("Failed to create new file")
                .audio_frame_writer()
        })
        .collect::<Result<Vec<_>, _>>()?;

    let mut buffer = input_format.create_frame_buffer(1);
    while input_wave_reader.read_integer_frame(&mut buffer)? > 0 {
        for (n, writer) in output_wave_writers.iter_mut().enumerate() {
            writer.write_integer_frames(&buffer[n..=n])?;
        }
    }

    for writer in output_wave_writers.drain(..) {
        writer.end()?;
    }

    Ok(())
}

fn main() -> io::Result<()> {
    let matches = App::new("wave-deinter")
        .version(crate_version!())
        .author(crate_authors!())
        .about("Extract each channel of a polyphonic wave file as a new monoaural wave file.")
        .arg(
            Arg::with_name("numeric_names")
                .long("numeric")
                .short("n")
                .help("Use numeric channel names \"01\" \"02\" etc.")
                .takes_value(false),
        )
        .arg(
            Arg::with_name("channel_delimiter")
                .long("delim")
                .short("d")
                .help("Channel label delimiter.")
                .default_value("."),
        )
        .arg(
            Arg::with_name("INPUT")
                .help("Input wave file")
                .required(true)
                .multiple(true),
        )
        .get_matches();

    let delimiter = matches.value_of("channel_delimiter").unwrap();
    let use_numeric_names = matches.is_present("numeric_names");
    let infile = matches.value_of("INPUT").unwrap();

    match process_file(infile, delimiter, use_numeric_names) {
        Err(Error::IOError(io)) => Err(io),
        Err(e) => panic!("Error: {:?}", e),
        Ok(()) => Ok(()),
    }
}