#![allow(clippy::manual_range_contains)]
#![warn(clippy::unreadable_literal, rust_2018_idioms)]
#![forbid(elided_lifetimes_in_paths, unsafe_code)]

mod iotro;
mod render;
mod time;

use crate::{
	render::{ffmpeg::FfmpegOutputFormat, Renderer},
	time::{parse_date, parse_time, Date, Time}
};
use camino::Utf8PathBuf as PathBuf;
use clap::Parser;
use rational::Rational;
use serde::{Deserialize, Serialize};
use serde_with::{serde_as, DisplayFromStr};
use std::{
	collections::BTreeSet,
	fmt::Display,
	fs,
	io::{self, BufRead as _, Write},
	str::FromStr,
	sync::RwLock
};

static MEM_LIMIT: RwLock<String> = RwLock::new(String::new());

#[derive(Debug, Parser)]
struct Args {
	/// The root directory of the project. It should contain the raw video file(s).
	#[clap(short = 'C', long, default_value = ".")]
	directory: PathBuf,

	/// The slug of the course, e.g. "23ws-malo2".
	#[clap(short = 'c', long, default_value = "23ws-malo2")]
	course: String,

	/// The memory limit for external tools like ffmpeg.
	#[clap(short, long, default_value = "8G")]
	mem_limit: String,

	/// Transcode the final video clip down to the minimum resolution specified.
	#[clap(short, long)]
	transcode: Option<Resolution>
}

macro_rules! resolutions {
	($($res:ident: $width:literal x $height:literal at $bitrate:literal in $format:ident),+) => {
		#[allow(non_camel_case_types, clippy::upper_case_acronyms)]
		#[derive(Clone, Copy, Debug, Deserialize, Eq, Ord, PartialEq, PartialOrd, Serialize)]
		enum Resolution {
			$(
				#[doc = concat!(stringify!($width), "x", stringify!($height))]
				$res
			),+
		}

		const NUM_RESOLUTIONS: usize = {
			let mut num = 0;
			$(num += 1; stringify!($res);)+
			num
		};

		impl Resolution {
			fn values() -> [Self; NUM_RESOLUTIONS] {
				[$(Self::$res),+]
			}

			fn width(self) -> usize {
				match self {
					$(Self::$res => $width),+
				}
			}

			fn height(self) -> usize {
				match self {
					$(Self::$res => $height),+
				}
			}

			fn bitrate(self) -> u64 {
				match self {
					$(Self::$res => $bitrate),+
				}
			}

			fn format(self) -> FfmpegOutputFormat {
				match self {
					$(Self::$res => FfmpegOutputFormat::$format),+
				}
			}
		}

		impl FromStr for Resolution {
			type Err = anyhow::Error;

			fn from_str(s: &str) -> anyhow::Result<Self> {
				Ok(match s {
					$(concat!(stringify!($height), "p") => Self::$res,)+
					_ => anyhow::bail!("Unknown Resolution: {s:?}")
				})
			}
		}
	}
}

resolutions! {
	nHD: 640 x 360 at 500_000 in AvcAac,
	HD: 1280 x 720 at 1_000_000 in AvcAac,
	FullHD: 1920 x 1080 at 2_000_000 in AvcAac,
	WQHD: 2560 x 1440 at 3_000_000 in Av1Opus,
	// TODO qsx muss mal sagen wieviel bitrate für 4k
	UHD: 3840 x 2160 at 4_000_000 in Av1Opus
}

#[derive(Deserialize, Serialize)]
struct Project {
	lecture: ProjectLecture,
	source: ProjectSource,
	progress: ProjectProgress
}

#[serde_as]
#[derive(Deserialize, Serialize)]
struct ProjectLecture {
	course: String,
	#[serde_as(as = "DisplayFromStr")]
	date: Date
}

#[serde_as]
#[derive(Deserialize, Serialize)]
struct ProjectSource {
	files: Vec<String>,

	#[serde_as(as = "Option<DisplayFromStr>")]
	start: Option<Time>,
	#[serde_as(as = "Option<DisplayFromStr>")]
	end: Option<Time>,
	#[serde_as(as = "Vec<(DisplayFromStr, DisplayFromStr)>")]
	fast: Vec<(Time, Time)>,

	metadata: Option<ProjectSourceMetadata>
}

#[serde_as]
#[derive(Deserialize, Serialize)]
struct ProjectSourceMetadata {
	/// The duration of the source video.
	#[serde_as(as = "DisplayFromStr")]
	source_duration: Time,
	/// The FPS of the source video.
	#[serde_as(as = "DisplayFromStr")]
	source_fps: Rational,
	/// The time base of the source video.
	#[serde_as(as = "DisplayFromStr")]
	source_tbn: Rational,
	/// The resolution of the source video.
	source_res: Resolution,
	/// The sample rate of the source audio.
	source_sample_rate: u32
}

#[derive(Default, Deserialize, Serialize)]
struct ProjectProgress {
	preprocessed: bool,
	asked_start_end: bool,
	asked_fast: bool,
	rendered: bool,
	transcoded: BTreeSet<Resolution>
}

fn ask_time(question: impl Display) -> Time {
	let mut stdout = io::stdout().lock();
	let mut stdin = io::stdin().lock();

	writeln!(stdout, "{question}").unwrap();
	let mut line = String::new();
	loop {
		line.clear();
		write!(stdout, "> ").unwrap();
		stdout.flush().unwrap();
		stdin.read_line(&mut line).unwrap();
		let line = line.trim();
		match parse_time(line) {
			Ok(time) => return time,
			Err(err) => writeln!(stdout, "Invalid Input {line:?}: {err}").unwrap()
		}
	}
}

fn main() {
	let args = Args::parse();
	*(MEM_LIMIT.write().unwrap()) = args.mem_limit;

	// process arguments
	let directory = args.directory.canonicalize_utf8().unwrap();
	let course = args.course;

	// let's see if we need to initialise the project
	let project_path = directory.join("project.toml");
	let mut project = if project_path.exists() {
		toml::from_slice(&fs::read(&project_path).unwrap()).unwrap()
	} else {
		let dirname = directory.file_name().unwrap();
		let date =
			parse_date(dirname).expect("Directory name is not in the expected format");

		let mut files = Vec::new();
		for entry in directory.read_dir_utf8().unwrap() {
			let entry = entry.unwrap();
			let name = entry.file_name();
			let lower = name.to_ascii_lowercase();
			if (lower.ends_with(".mp4") || lower.ends_with(".mts"))
				&& entry.file_type().unwrap().is_file()
			{
				files.push(String::from(name));
			}
		}
		files.sort_unstable();
		assert!(!files.is_empty());
		println!("I found the following source files: {files:?}");

		let project = Project {
			lecture: ProjectLecture { course, date },
			source: ProjectSource {
				files,
				start: None,
				end: None,
				fast: Vec::new(),
				metadata: None
			},
			progress: Default::default()
		};
		fs::write(&project_path, toml::to_string(&project).unwrap().as_bytes()).unwrap();
		project
	};

	println!("{}", toml::to_string(&project).unwrap());

	let renderer = Renderer::new(&directory, &project).unwrap();
	let recording = renderer.recording_mkv();

	// preprocess the video
	if !project.progress.preprocessed {
		renderer.preprocess(&mut project).unwrap();
		project.progress.preprocessed = true;

		println!("{}", toml::to_string(&project).unwrap());
		fs::write(&project_path, toml::to_string(&project).unwrap().as_bytes()).unwrap();
	}

	// ask the user about start and end times
	if !project.progress.asked_start_end {
		project.source.start = Some(ask_time(format_args!(
			"Please take a look at the file {recording} and tell me the first second you want included"
		)));
		project.source.end = Some(ask_time(format_args!(
			"Please take a look at the file {recording} and tell me the last second you want included"
		)));
		project.progress.asked_start_end = true;

		println!("{}", toml::to_string(&project).unwrap());
		fs::write(&project_path, toml::to_string(&project).unwrap().as_bytes()).unwrap();
	}

	// ask the user about fast forward times
	if !project.progress.asked_fast {
		loop {
			let start = ask_time(format_args!(
				"Please take a look at the file {recording} and tell me the first second you want fast-forwarded. You may reply with `0` if there are no more fast-forward sections"
			));
			if start.seconds == 0 && start.micros == 0 {
				break;
			}
			let end = ask_time(format_args!(
				"Please tell me the last second you want fast-forwarded"
			));
			project.source.fast.push((start, end));
		}
		project.progress.asked_fast = true;

		println!("{}", toml::to_string(&project).unwrap());
		fs::write(&project_path, toml::to_string(&project).unwrap().as_bytes()).unwrap();
	}

	// render the video
	let mut videos = Vec::new();
	videos.push(if project.progress.rendered {
		renderer.video_file_output()
	} else {
		let video = renderer.render(&mut project).unwrap();
		project.progress.rendered = true;

		println!("{}", toml::to_string(&project).unwrap());
		fs::write(&project_path, toml::to_string(&project).unwrap().as_bytes()).unwrap();

		video
	});

	// rescale the video
	if let Some(lowest_res) = args.transcode {
		for res in Resolution::values().into_iter().rev() {
			if res >= project.source.metadata.as_ref().unwrap().source_res
				|| res < lowest_res
			{
				continue;
			}
			if !project.progress.transcoded.contains(&res) {
				videos.push(renderer.rescale(res).unwrap());
				project.progress.transcoded.insert(res);

				println!("{}", toml::to_string(&project).unwrap());
				fs::write(&project_path, toml::to_string(&project).unwrap().as_bytes())
					.unwrap();
			}
		}
	}

	println!("\x1B[1m ==> DONE :)\x1B[0m");
	println!("     Videos:");
	for v in &videos {
		println!("     -> {v}");
	}
}