extern crate ferretro;
extern crate ffmpeg4 as ffmpeg;

use std::collections::VecDeque;
use std::io::Read;
use std::path::{Path, PathBuf};
use std::pin::Pin;

use structopt::StructOpt;
use failure::Fallible;

use ferretro::retro;
use ferretro::retro::ffi::{PixelFormat, GameGeometry, SystemAvInfo, SystemInfo};
use ferretro::retro::wrapper::{LibretroWrapper, Handler};

use ffmpeg::{format, filter, frame, media, ChannelLayout};
use ffmpeg::util::rational::Rational;

struct MyEmulator {
    retro: retro::wrapper::LibretroWrapper,
    sys_info: SystemInfo,
    audio_buf: Vec<(i16, i16)>,
    video_pixel_format: format::Pixel,
    video_frames: VecDeque<frame::Video>,
    video_encoder: ffmpeg::encoder::Video,
    audio_encoder: ffmpeg::encoder::Audio,
    video_filter: filter::Graph,
    audio_filter: filter::Graph,
    sys_path: Option<PathBuf>,
}

fn video_filter(
    video_encoder: &ffmpeg::encoder::video::Video,
    av_info: &SystemAvInfo,
    pix_fmt: PixelFormat,
) -> Result<filter::Graph, ffmpeg::Error> {
    let mut vfilter = filter::Graph::new();
    let pix_fmt = match pix_fmt {
        PixelFormat::ARGB1555 => if cfg!(target_endian = "big") { "rgb555be" } else { "rgb555le" },
        PixelFormat::ARGB8888 => "argb",
        PixelFormat::RGB565 => if cfg!(target_endian = "big") { "rgb565be" } else { "rgb565le" },
    };
    let pixel_aspect = av_info.geometry.aspect_ratio / (av_info.geometry.base_width as f32 / av_info.geometry.base_height as f32);
    let args = format!(
        "buffer=width={}:height={}:pix_fmt={}:frame_rate={}:pixel_aspect={}",
        av_info.geometry.base_width,
        av_info.geometry.base_height,
        pix_fmt,
        av_info.timing.fps,
        pixel_aspect,
    );
    vfilter.add(&filter::find("buffer").unwrap(), "in", &args);
    //scale?
    vfilter.add(&filter::find("buffersink").unwrap(), "out", "");

    {
        let mut out = vfilter.get("out").unwrap();
        out.set_pixel_format(video_encoder.format());
    }

    vfilter.output("in", 0)?
        .input("out", 0)?;
    vfilter.validate()?;

    Ok(vfilter)
}

fn audio_filter(
    audio_encoder: &ffmpeg::encoder::audio::Audio,
    sample_rate: f64,
) -> Result<filter::Graph, ffmpeg::Error> {
    let mut afilter = filter::Graph::new();
    let args = format!("sample_rate={}:sample_fmt=s16:channel_layout=stereo", sample_rate);
    afilter.add(&filter::find("abuffer").unwrap(), "in", &args);
    //aresample?
    afilter.add(&filter::find("abuffersink").unwrap(), "out", "");

    {
        let mut out = afilter.get("out").unwrap();
        out.set_sample_format(audio_encoder.format());
        out.set_channel_layout(audio_encoder.channel_layout());
        out.set_sample_rate(audio_encoder.rate());
    }

    afilter.output("in", 0)?
        .input("out", 0)?;
    afilter.validate()?;

    Ok(afilter)
}

impl MyEmulator {
    pub fn new(
        core_path: impl AsRef<Path>,
        sys_path: &Option<impl AsRef<Path>>,
        mut video_encoder: ffmpeg::encoder::video::Video,
        mut audio_encoder: ffmpeg::encoder::audio::Audio,
    ) -> Pin<Box<Self>> {
        let lib = libloading::Library::new(core_path.as_ref()).unwrap();
        let raw_retro = retro::loading::LibretroApi::from_library(lib).unwrap();
        let retro = retro::wrapper::LibretroWrapper::from(raw_retro);

        let sys_info = retro.get_system_info();
        let av_info = retro.get_system_av_info();

        video_encoder.set_time_base(Rational::new(1, av_info.timing.fps.round() as i32));
        video_encoder.set_frame_rate(av_info.timing.fps.into());
        video_encoder.set_width(av_info.geometry.base_width);
        video_encoder.set_height(av_info.geometry.base_height);
        video_encoder.set_aspect_ratio(av_info.geometry.aspect_ratio as f64);

        audio_encoder.set_rate(system_av_info.timing.sample_rate.round() as i32);

        let video_filter = video_filter(&video_encoder, &av_info).unwrap();
        let audio_filter = audio_filter(&audio_encoder, av_info.timing.sample_rate).unwrap();

        let video_encoder = video_encoder.open().unwrap();
        let audio_encoder = audio_encoder.open().unwrap();

        let emu = MyEmulator {
            retro,
            sys_info,
            audio_buf: Default::default(),
            video_pixel_format: format::Pixel::RGB555,
            video_frames: Default::default(),
            video_encoder,
            audio_encoder,
            video_filter,
            audio_filter,
            sys_path: sys_path.as_ref().map(|x| x.as_ref().to_path_buf()),
        };

        let mut pin_emu = Box::pin(emu);
        retro::wrapper::set_handler(pin_emu.as_mut());
        pin_emu.retro.init();
        pin_emu.set_system_av_info(av_info);
        pin_emu
    }

    pub fn run(&mut self) {
        self.retro.run();

        let vframe = self.video_frames.pop_front().unwrap();
        let mut aframe = frame::Audio::new(
            format::Sample::I16(format::sample::Type::Packed),
            self.audio_buf.len(),
            ChannelLayout::STEREO
        );
        let aplane: &mut [(i16, i16)] = aframe.plane_mut(0);
        aplane.copy_from_slice(self.audio_buf.as_ref());
        self.audio_buf.clear();

        let mut out = ffmpeg::Packet::empty();
        self.video_encoder.encode(&vframe, &mut out).unwrap();
        self.audio_encoder.encode(&aframe, &mut out).unwrap();
    }

    pub fn load_game(&self, rom: impl AsRef<Path>) {
        let path = rom.as_ref();
        let mut data = None;
        let mut v = Vec::new();
        if !self.sys_info.need_fullpath {
            if let Ok(mut f) = std::fs::File::open(path) {
                if f.read_to_end(&mut v).is_ok() {
                    data = Some(v.as_ref());
                }
            }
        }
        self.retro
            .load_game(Some(path), data, None)
            .unwrap();
    }
}

impl retro::wrapper::Handler for MyEmulator {
    fn libretro_core(&mut self) -> &mut LibretroWrapper {
        &mut self.retro
    }

    fn video_refresh(&mut self, data: &[u8], width: u32, height: u32, pitch: u32) {
        let mut vframe = frame::Video::new(self.video_pixel_format, width, height);

        let stride = vframe.stride(0);
        let pitch = pitch as usize;

        let vplane = vframe.data_mut(0);
        if data.len() == vplane.len() && pitch == stride {
            vplane.copy_from_slice(&data);
        } else {
            for y in 0..(height as usize) {
                let ffbegin = y * stride;
                let lrbegin = y * pitch;
                let min = usize::min(stride, pitch);
                vplane[ffbegin..(ffbegin + min)].copy_from_slice(
                    &data[lrbegin..(lrbegin + min)]
                );
            }
        }

        self.video_frames.push_back(vframe);
    }

    fn audio_sample(&mut self, left: i16, right: i16) {
        self.audio_buf.push((left, right));
    }

    fn audio_sample_batch(&mut self, stereo_pcm: &[i16]) -> usize {
        let left_iter = stereo_pcm.iter().step_by(2).cloned();
        let right_iter = stereo_pcm.iter().skip(1).step_by(2).cloned();
        self.audio_buf.extend(Iterator::zip(left_iter, right_iter));
        stereo_pcm.len()
    }

    fn get_can_dupe(&mut self) -> Option<bool> { Some(false) }

    fn get_system_directory(&mut self) -> Option<PathBuf> {
        self.sys_path.clone()
    }

    fn set_pixel_format(&mut self, format: PixelFormat) -> bool {
        self.video_pixel_format = match format {
            PixelFormat::ARGB1555 => format::Pixel::RGB555,
            PixelFormat::ARGB8888 => format::Pixel::RGB32,
            PixelFormat::RGB565 => format::Pixel::RGB565,
        };
        true
    }

    fn set_system_av_info(&mut self, system_av_info: SystemAvInfo) -> bool {
        self.video_encoder.set_frame_rate(system_av_info.timing.fps.into());
        self.audio_encoder.set_rate(system_av_info.timing.sample_rate.round() as i32);
        self.set_geometry(system_av_info.geometry);
        true
    }

    fn set_geometry(&mut self, geometry: GameGeometry) -> bool {
        self.video_encoder.set_width(geometry.base_width);
        self.video_encoder.set_height(geometry.base_height);
        self.video_encoder.set_aspect_ratio(geometry.aspect_ratio as f64);
        true
    }
}

#[derive(StructOpt)]
struct Opt {
    /// Core module to use.
    #[structopt(short, long, parse(from_os_str))]
    core: PathBuf,
    /// ROM to load using the core.
    #[structopt(short, long, parse(from_os_str))]
    rom: PathBuf,
    /// Recorded video to write.
    #[structopt(short, long, parse(from_os_str))]
    video: PathBuf,
    /// System directory, often containing BIOS files
    #[structopt(short, long, parse(from_os_str))]
    system: Option<PathBuf>,
}

fn main() -> Fallible<()> {
    let opt: Opt = Opt::from_args();
    ffmpeg::init().unwrap();

    let mut octx = format::output(&opt.video)?;

    let detected_vcodec = octx.format().codec(&opt.video, media::Type::Video);
    let detected_acodec = octx.format().codec(&opt.video, media::Type::Audio);

    let vcodec = ffmpeg::encoder::find(detected_vcodec).unwrap().video()?;
    let acodec = ffmpeg::encoder::find(detected_acodec).unwrap().audio()?;

    let mut video_encoder = octx.add_stream(vcodec)?.codec().encoder().video()?;
    let mut audio_encoder = octx.add_stream(acodec)?.codec().encoder().audio()?;

    video_encoder.set_bit_rate(64000);
    video_encoder.set_format(video_encoder.codec().unwrap().video()?.formats().unwrap().nth(0).unwrap());

    audio_encoder.set_bit_rate(64000);
    audio_encoder.set_rate(44100);
    audio_encoder.set_format(audio_encoder.codec().unwrap().audio()?.formats().unwrap().nth(0).unwrap());
    audio_encoder.set_channels(2);
    audio_encoder.set_channel_layout(ChannelLayout::STEREO);

    let mut emu = MyEmulator::new(opt.core, &opt.system, video_encoder, audio_encoder);
    emu.load_game(opt.rom);

    octx.write_header().unwrap();

    for _ in 0..60*60 {
        emu.run();
    }

    octx.write_trailer().unwrap();
    Ok(())
}