#![allow(warnings)]

pub mod ffmpeg;
mod filter;

use self::{ffmpeg::FfmpegOutput, filter::Filter};
use crate::{
	iotro::{intro, outro},
	render::ffmpeg::{Ffmpeg, FfmpegInput},
	time::{format_date, Time},
	Project, ProjectSourceMetadata, Resolution, MEM_LIMIT
};
use anyhow::{bail, Context};
use camino::{Utf8Path as Path, Utf8PathBuf as PathBuf};
use rational::Rational;
use std::{
	borrow::Cow,
	collections::VecDeque,
	fs::{self, File},
	io::Write as _,
	process::{Command, Stdio}
};

const INTRO_LEN: Time = Time {
	seconds: 3,
	micros: 0
};
const OUTRO_LEN: Time = Time {
	seconds: 5,
	micros: 0
};
const TRANSITION_LEN: Time = Time {
	seconds: 0,
	micros: 200_000
};
const FF_MULTIPLIER: usize = 8;
// logo sizes at full hd, will be scaled to source resolution
const FF_LOGO_SIZE: usize = 128;
const LOGO_SIZE: usize = 96;

fn cmd() -> Command {
	// we use systemd-run to limit the process memory
	// I tried others like ulimit, chpst or isolate, but none worked
	let mut cmd = Command::new("systemd-run");
	cmd.arg("--scope")
		.arg("-q")
		.arg("--expand-environment=no")
		.arg("-p")
		.arg(format!("MemoryMax={}", MEM_LIMIT.read().unwrap()))
		.arg("--user");
	// we use busybox ash for having a shell that outputs commands with -x
	cmd.arg("busybox")
		.arg("ash")
		.arg("-exuo")
		.arg("pipefail")
		.arg("-c")
		.arg("exec \"$0\" \"${@}\"");
	cmd
}

fn ffprobe() -> Command {
	let mut cmd = cmd();
	cmd.arg("ffprobe")
		.arg("-v")
		.arg("error")
		.arg("-of")
		.arg("default=noprint_wrappers=1:nokey=1");
	cmd
}

fn read_output(cmd: &mut Command) -> anyhow::Result<String> {
	let out = cmd.stderr(Stdio::inherit()).output()?;
	if !out.status.success() {
		bail!(
			"Executed command failed with exit status {:?}",
			out.status.code()
		);
	}
	String::from_utf8(out.stdout)
		.context("Command returned non-utf8 output")
		.map(|str| str.trim().into())
}

fn ffprobe_video(query: &str, input: &Path) -> anyhow::Result<String> {
	read_output(
		ffprobe()
			.arg("-select_streams")
			.arg("v:0")
			.arg("-show_entries")
			.arg(query)
			.arg(input)
	)
}

fn ffprobe_audio(query: &str, concat_input: &Path) -> anyhow::Result<String> {
	read_output(
		ffprobe()
			.arg("-select_streams")
			.arg("a:0")
			.arg("-show_entries")
			.arg(query)
			.arg("-safe")
			.arg("0")
			.arg("-f")
			.arg("concat")
			.arg(concat_input)
	)
}

pub(crate) struct Renderer<'a> {
	/// The directory with all the sources.
	directory: &'a Path,

	/// The slug (i.e. 23ws-malo2-231016).
	slug: String,
	/// The target directory.
	target: PathBuf
}

fn svg2mp4(
	meta: &ProjectSourceMetadata,
	svg: PathBuf,
	mp4: PathBuf,
	duration: Time
) -> anyhow::Result<()> {
	let mut ffmpeg = Ffmpeg::new(FfmpegOutput {
		fps: None,
		duration: Some(duration),
		time_base: Some(meta.source_tbn),
		fps_mode_vfr: true,
		faststart: false,
		path: mp4
	});
	ffmpeg.add_input(FfmpegInput {
		loop_input: true,
		fps: Some(meta.source_fps),
		..FfmpegInput::new(svg)
	});
	ffmpeg.add_filter(Filter::GenerateSilence {
		video: "0".into(),
		output: "out".into()
	});
	ffmpeg.set_filter_output("out");
	ffmpeg.run()
}

fn svg2png(svg: &Path, png: &Path, size: usize) -> anyhow::Result<()> {
	let mut cmd = cmd();
	let size = size.to_string();
	cmd.arg("inkscape")
		.arg("-w")
		.arg(&size)
		.arg("-h")
		.arg(&size);
	cmd.arg(svg).arg("-o").arg(png);

	let status = cmd.status()?;
	if status.success() {
		Ok(())
	} else {
		bail!("inkscape failed with exit code {:?}", status.code())
	}
}

impl<'a> Renderer<'a> {
	pub(crate) fn new(directory: &'a Path, project: &Project) -> anyhow::Result<Self> {
		let slug = format!(
			"{}-{}",
			project.lecture.course,
			format_date(project.lecture.date)
		);
		let target = directory.join(&slug);
		fs::create_dir_all(&target)?;

		Ok(Self {
			directory,
			slug,
			target
		})
	}

	pub(crate) fn recording_mp4(&self) -> PathBuf {
		self.target.join("recording.mp4")
	}

	pub(crate) fn preprocess(&self, project: &mut Project) -> anyhow::Result<()> {
		assert!(!project.progress.preprocessed);

		let recording_txt = self.target.join("recording.txt");
		let mut file = File::create(&recording_txt)?;
		for filename in &project.source.files {
			writeln!(file, "file '{}'", self.directory.join(filename).to_string());
		}
		drop(file);

		println!("\x1B[1m ==> Concatenating Video and Normalising Audio ...\x1B[0m");
		let source_sample_rate =
			ffprobe_audio("stream=sample_rate", &recording_txt)?.parse()?;
		let recording_mp4 = self.recording_mp4();
		let mut ffmpeg = Ffmpeg::new(FfmpegOutput::new(recording_mp4.clone()));
		ffmpeg.add_input(FfmpegInput {
			concat: true,
			..FfmpegInput::new(recording_txt)
		});
		ffmpeg.enable_loudnorm();
		ffmpeg.run()?;

		let width = ffprobe_video("stream=width", &recording_mp4)?.parse()?;
		let height = ffprobe_video("stream=height", &recording_mp4)?.parse()?;
		let source_res = match (width, height) {
			(3840, 2160) => Resolution::UHD,
			(2560, 1440) => Resolution::WQHD,
			(1920, 1080) => Resolution::FullHD,
			(1280, 720) => Resolution::HD,
			(640, 360) => Resolution::nHD,
			(width, height) => bail!("Unknown resolution: {width}x{height}")
		};
		project.source.metadata = Some(ProjectSourceMetadata {
			source_duration: ffprobe_video("format=duration", &recording_mp4)?.parse()?,
			source_fps: ffprobe_video("stream=r_frame_rate", &recording_mp4)?.parse()?,
			source_tbn: ffprobe_video("stream=time_base", &recording_mp4)?.parse()?,
			source_res,
			source_sample_rate
		});
		let metadata = project.source.metadata.as_ref().unwrap();

		println!("\x1B[1m ==> Preparing assets ...\x1B[0m");

		// render intro to svg then mp4
		let intro_svg = self.target.join("intro.svg");
		fs::write(
			&intro_svg,
			intro(source_res, project.lecture.date)
				.to_string_pretty()
				.into_bytes()
		)?;
		let intro_mp4 = self.target.join("intro.mp4");
		svg2mp4(metadata, intro_svg, intro_mp4, INTRO_LEN)?;

		// render outro to svg then mp4
		let outro_svg = self.target.join("outro.svg");
		fs::write(
			&outro_svg,
			outro(source_res).to_string_pretty().into_bytes()
		)?;
		let outro_mp4 = self.target.join("outro.mp4");
		svg2mp4(metadata, outro_svg, outro_mp4, OUTRO_LEN)?;

		// copy logo then render to png
		let logo_svg = self.target.join("logo.svg");
		fs::write(
			&logo_svg,
			include_bytes!(concat!(env!("CARGO_MANIFEST_DIR"), "/assets/logo.svg"))
		)?;
		let logo_png = self.target.join("logo.png");
		svg2png(&logo_svg, &logo_png, LOGO_SIZE * source_res.width() / 1920)?;

		// copy fastforward then render to png
		let fastforward_svg = self.target.join("fastforward.svg");
		fs::write(
			&fastforward_svg,
			include_bytes!(concat!(
				env!("CARGO_MANIFEST_DIR"),
				"/assets/fastforward.svg"
			))
		)?;
		let fastforward_png = self.target.join("fastforward.png");
		svg2png(
			&fastforward_svg,
			&fastforward_png,
			FF_LOGO_SIZE * source_res.width() / 1920
		)?;

		Ok(())
	}

	fn video_mp4_res(&self, res: Resolution) -> PathBuf {
		self.target
			.join(format!("{}-{}p.mp4", self.slug, res.height()))
	}

	pub(crate) fn video_mp4(&self, project: &Project) -> PathBuf {
		self.video_mp4_res(project.source.metadata.as_ref().unwrap().source_res)
	}

	pub(crate) fn render(&self, project: &mut Project) -> anyhow::Result<PathBuf> {
		let output = self.video_mp4(project);
		let mut ffmpeg = Ffmpeg::new(FfmpegOutput::new(output.clone()));

		// add all of our inputs
		let intro = ffmpeg.add_input(FfmpegInput::new(self.target.join("intro.mp4")));
		let rec_file = self.target.join("recording.mp4");
		let outro = ffmpeg.add_input(FfmpegInput::new(self.target.join("outro.mp4")));
		let logo = ffmpeg.add_input(FfmpegInput::new(self.target.join("logo.png")));
		let ff = ffmpeg.add_input(FfmpegInput::new(self.target.join("fastforward.png")));

		let mut part1: Cow<'static, str> = intro.into();
		let mut part3: Cow<'static, str> = outro.into();

		// the recording is fun because of all the fast forwarding
		let mut part2 = VecDeque::new();
		let mut part2_start_of_the_end = None;
		let mut part2_end_of_the_start = None;

		// ok so ff is fun. we will add the ff'ed section as well as the part between
		// the previous ff'ed section and our new section, unless we are the first
		project.source.fast.sort();
		for (i, (ff_st, ff_end)) in project.source.fast.iter().rev().enumerate() {
			if let Some(prev_end) = part2_end_of_the_start {
				let recffbetween = ffmpeg.add_input(FfmpegInput {
					start: Some(*ff_end),
					duration: Some(prev_end - *ff_end),
					..FfmpegInput::new(rec_file.clone())
				});
				part2.push_front(recffbetween.into());
			} else {
				part2_start_of_the_end = Some(*ff_end);
			}
			part2_end_of_the_start = Some(*ff_st);

			let recffpart = ffmpeg.add_input(FfmpegInput {
				start: Some(*ff_st),
				duration: Some(*ff_end - *ff_st),
				..FfmpegInput::new(rec_file.clone())
			});

			let recff = format!("recff{i}");
			ffmpeg.add_filter(Filter::FastForward {
				input: recffpart.into(),
				ffinput: ff.clone().into(),
				multiplier: FF_MULTIPLIER,
				output: recff.clone().into()
			});
			part2.push_front(recff.into());
		}

		// if the recording was not ff'ed, perform a normal trim
		let start = project.source.start.unwrap();
		let end = project.source.end.unwrap();
		let part2_last_part_duration;
		if part2.is_empty() {
			part2_last_part_duration = end - start;
			let rectrim = ffmpeg.add_input(FfmpegInput {
				start: Some(start),
				duration: Some(part2_last_part_duration),
				..FfmpegInput::new(rec_file.clone())
			});
			part2.push_back(rectrim.into());
		}
		// otherwise add the first and last parts separately
		else {
			let rectrimst = ffmpeg.add_input(FfmpegInput {
				start: Some(start),
				duration: Some(part2_end_of_the_start.unwrap() - start),
				..FfmpegInput::new(rec_file.clone())
			});
			part2.push_front(rectrimst.into());

			part2_last_part_duration = end - part2_start_of_the_end.unwrap();
			let rectrimend = ffmpeg.add_input(FfmpegInput {
				start: Some(part2_start_of_the_end.unwrap()),
				duration: Some(part2_last_part_duration),
				..FfmpegInput::new(rec_file.clone())
			});
			part2.push_back(rectrimend.into());
		}

		// fade out the intro
		let introfade = "introfade";
		ffmpeg.add_filter(Filter::Fade {
			input: part1,
			direction: "out",
			start: INTRO_LEN - TRANSITION_LEN,
			duration: TRANSITION_LEN,
			output: introfade.into()
		});
		part1 = introfade.into();

		// fade in the recording
		let recfadein = "recfadein";
		ffmpeg.add_filter(Filter::Fade {
			input: part2.pop_front().unwrap(),
			direction: "in",
			start: Time {
				seconds: 0,
				micros: 0
			},
			duration: TRANSITION_LEN,
			output: recfadein.into()
		});
		part2.push_front(recfadein.into());

		// fade out the recording
		let recfadeout = "recfadeout";
		ffmpeg.add_filter(Filter::Fade {
			input: part2.pop_back().unwrap(),
			direction: "out",
			start: part2_last_part_duration - TRANSITION_LEN,
			duration: TRANSITION_LEN,
			output: recfadeout.into()
		});
		part2.push_back(recfadeout.into());

		// fade in the outro
		let outrofade = "outrofade";
		ffmpeg.add_filter(Filter::Fade {
			input: part3,
			direction: "in",
			start: Time {
				seconds: 0,
				micros: 0
			},
			duration: TRANSITION_LEN,
			output: outrofade.into()
		});
		part3 = outrofade.into();

		// concatenate everything
		let mut parts = part2;
		parts.push_front(part1);
		parts.push_back(part3);
		let concat = "concat";
		ffmpeg.add_filter(Filter::Concat {
			inputs: parts,
			output: concat.into()
		});

		// overlay the logo
		let logoalpha = "logoalpha";
		ffmpeg.add_filter(Filter::Alpha {
			input: logo.into(),
			alpha: 0.5,
			output: logoalpha.into()
		});
		let overlay = "overlay";
		ffmpeg.add_filter(Filter::Overlay {
			video_input: concat.into(),
			overlay_input: logoalpha.into(),
			x: "main_w-overlay_w-130".into(),
			y: "main_h-overlay_h-65".into(),
			output: overlay.into()
		});

		// we're done :)
		ffmpeg.set_filter_output(overlay);
		ffmpeg.set_video_bitrate(
			project
				.source
				.metadata
				.as_ref()
				.unwrap()
				.source_res
				.bitrate() * 3
		);
		ffmpeg.run()?;

		Ok(output)
	}

	pub fn rescale(&self, res: Resolution, project: &Project) -> anyhow::Result<PathBuf> {
		let input = self.video_mp4(project);
		let output = self.video_mp4_res(res);
		println!("\x1B[1m ==> Rescaling to {}p\x1B[0m", res.height());

		let mut ffmpeg =
			Ffmpeg::new(FfmpegOutput::new(output.clone()).enable_faststart());
		ffmpeg.add_input(FfmpegInput::new(input));
		ffmpeg.rescale_video(res);
		ffmpeg.set_video_bitrate(res.bitrate());
		ffmpeg.run()?;
		Ok(output)
	}
}