//! A module for writing intros and outros

use crate::{time::Date, ProjectLecture, Resolution};
use anyhow::anyhow;
use std::{
	fmt::{self, Debug, Display, Formatter},
	str::FromStr
};
use svgwriter::{
	tags::{Group, Rect, TagWithPresentationAttributes, Text},
	Graphic
};

#[derive(Clone)]
pub struct Language<'a> {
	lang: &'a str,
	format_date_long: fn(Date) -> String,
	// intro
	lecture_from: &'a str,
	video_created_by_us: &'a str,
	// outro
	video_created_by: &'a str,
	our_website: &'a str,
	download_videos: &'a str,
	questions_feedback: &'a str
}

pub const GERMAN: Language<'static> = Language {
	lang: "de",

	// Format a date in DD. MMMM YYYY format.
	format_date_long: |d: Date| {
		let month = match d.month {
			1 => "Januar",
			2 => "Februar",
			3 => "März",
			4 => "April",
			5 => "Mai",
			6 => "Juni",
			7 => "Juli",
			8 => "August",
			9 => "September",
			10 => "Oktober",
			11 => "November",
			12 => "Dezember",
			_ => unreachable!()
		};
		format!("{:02}. {month} {:04}", d.day, d.year)
	},

	lecture_from: "Vorlesung vom",
	video_created_by_us: "Video erstellt von der Video AG, Fachschaft I/1",

	video_created_by: "Video erstellt von der",
	our_website: "Website der Fachschaft",
	download_videos: "Videos herunterladen",
	questions_feedback: "Fragen, Vorschläge und Feedback"
};

pub const BRITISH: Language<'static> = Language {
	lang: "uk",

	// Format a date in DDth MMMM YYYY format.
	format_date_long: |d: Date| {
		let month = match d.month {
			1 => "January",
			2 => "February",
			3 => "March",
			4 => "April",
			5 => "May",
			6 => "June",
			7 => "July",
			8 => "August",
			9 => "September",
			10 => "October",
			11 => "November",
			12 => "December",
			_ => unreachable!()
		};
		let th = match d.day {
			1 | 21 | 31 => "st",
			2 | 22 => "nd",
			3 | 23 => "rd",
			_ => "th"
		};
		format!("{:02}{th} {month} {:04}", d.day, d.year)
	},

	lecture_from: "Lecture from",
	video_created_by_us: "Video created by the Video AG, Fachschaft I/1",
	video_created_by: "Video created by the",
	our_website: "The Fachschaft's website",
	download_videos: "Download videos",
	questions_feedback: "Questions, Suggestions and Feedback"
};

impl FromStr for Language<'static> {
	type Err = anyhow::Error;

	fn from_str(s: &str) -> Result<Self, Self::Err> {
		match s {
			"de" => Ok(GERMAN),
			"en" | "uk" => Ok(BRITISH),
			lang => Err(anyhow!("Unknown language {lang:?}"))
		}
	}
}

impl Display for Language<'_> {
	fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
		f.write_str(self.lang)
	}
}

impl Debug for Language<'_> {
	fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
		f.debug_struct("Language")
			.field("lang", &self.lang)
			.finish_non_exhaustive()
	}
}

#[repr(u16)]
enum FontSize {
	Huge = 72,
	Large = 56,
	Big = 44
}

#[repr(u16)]
enum FontWeight {
	Normal = 400,
	SemiBold = 500,
	Bold = 700
}

struct Iotro {
	res: Resolution,
	g: Group
}

impl Iotro {
	fn new(res: Resolution) -> Self {
		Self {
			res,
			g: Group::new()
				.with_fill("white")
				.with_text_anchor("middle")
				.with_dominant_baseline("hanging")
				.with_font_family("Noto Sans")
		}
	}

	fn add_text<T: Into<String>>(
		&mut self,
		font_size: FontSize,
		font_weight: FontWeight,
		y_top: usize,
		content: T
	) {
		let mut text = Text::new()
			.with_x(960)
			.with_y(y_top)
			.with_font_size(font_size as u16)
			.with_font_weight(font_weight as u16);
		text.push(content.into());
		self.g.push(text);
	}

	fn finish(self) -> Graphic {
		let mut svg = Graphic::new();
		svg.set_width(self.res.width());
		svg.set_height(self.res.height());
		svg.set_view_box("0 0 1920 1080");
		svg.push(
			Rect::new()
				.with_fill("black")
				.with_x(0)
				.with_y(0)
				.with_width(1920)
				.with_height(1080)
		);
		svg.push(self.g);
		svg
	}
}

pub(crate) fn intro(res: Resolution, lecture: &ProjectLecture) -> Graphic {
	use self::{FontSize::*, FontWeight::*};

	let lang = &lecture.lang;
	let mut intro = Iotro::new(res);
	intro.add_text(Huge, Bold, 110, &lecture.label);
	intro.add_text(Huge, SemiBold, 250, &lecture.docent);
	intro.add_text(
		Huge,
		SemiBold,
		460,
		format!(
			"{} {}",
			lang.lecture_from,
			(lang.format_date_long)(lecture.date)
		)
	);
	intro.add_text(Big, Normal, 870, lang.video_created_by_us);
	intro.add_text(Big, Normal, 930, "https://video.fsmpi.rwth-aachen.de");
	intro.add_text(Big, Normal, 990, "video@fsmpi.rwth-aachen.de");

	intro.finish()
}

pub(crate) fn outro(lang: &Language<'_>, res: Resolution) -> Graphic {
	use self::{FontSize::*, FontWeight::*};

	let mut outro = Iotro::new(res);
	outro.add_text(Large, SemiBold, 50, lang.video_created_by);
	outro.add_text(Huge, Bold, 210, "Video AG, Fachschaft I/1");
	outro.add_text(Large, Normal, 360, format!("{}:", lang.our_website));
	outro.add_text(Large, Normal, 430, "https://www.fsmpi.rwth-aachen.de");
	outro.add_text(Large, Normal, 570, format!("{}:", lang.download_videos));
	outro.add_text(Large, Normal, 640, "https://video.fsmpi.rwth-aachen.de");
	outro.add_text(Large, Normal, 780, format!("{}:", lang.questions_feedback));
	outro.add_text(Large, Normal, 850, "video@fsmpi.rwth-aachen.de");

	outro.finish()
}