use std::{env, sync::OnceLock, time::Duration};

use dioxus::{
	desktop::{Config, LogicalSize, WindowBuilder},
	prelude::*,
};
use models::{Question, Questions};
use rand::seq::SliceRandom;

mod models;

const DEFAULT_FILE: &str = "questions.toml";
const MAIN_CSS: Asset = asset!("/assets/main.css");

pub static QUESTIONS: OnceLock<Questions> = OnceLock::new();

fn get_questions() -> Questions {
	QUESTIONS
		.get_or_init(|| {
			let args: Vec<String> = env::args().collect();
			let file_name = args.get(1).map(|x| x.as_str()).unwrap_or(DEFAULT_FILE);

			let questions_str = std::fs::read_to_string(file_name)
				.unwrap_or_else(|_| panic!("Could not read from file {file_name}"));
			let mut questions: Questions =
				toml::from_str(&questions_str).expect("Could not decode the given file as TOML");

			if args.len() > 2 {
				for i in 2..args.len() {
					let file_name = args.get(i).map(|x| x.as_str());
					let Some(file_name) = file_name else {
						continue;
					};

					let Ok(questions_str) = std::fs::read_to_string(file_name) else {
						continue;
					};

					let Ok(other_questions) = toml::from_str(&questions_str) else {
						continue;
					};

					questions += other_questions;
				}
			}

			questions
		})
		.clone()
}

fn get_rand_questions() -> Vec<Question> {
	let mut questions = get_questions().questions;
	let mut rng = rand::rng();

	// Randomize the answers
	questions
		.iter_mut()
		.for_each(|q| q.answers.shuffle(&mut rng));

	// Randomize the questions list
	questions.shuffle(&mut rng);

	questions
}

fn main() {
	dioxus::LaunchBuilder::new()
		.with_cfg(
			Config::default().with_menu(None).with_window(
				WindowBuilder::new()
					.with_min_inner_size(LogicalSize::new(640, 540))
					.with_maximized(true)
					.with_title("Flashcards"),
			),
		)
		.launch(App)
}

#[component]
fn App() -> Element {
	rsx! {
		document::Link { rel: "stylesheet", href: MAIN_CSS }
		QuestionForm {}
	}
}

#[component]
pub fn QuestionForm() -> Element {
	let mut questions = use_signal(get_rand_questions);
	let mut current = use_signal(move || questions.remove(0));

	let total_correct = use_memo(move || {
		current
			.read()
			.answers
			.iter()
			.filter(|a| a.is_correct.unwrap_or_default())
			.count()
	});
	let actual_correct = use_memo(move || {
		let current_lock = current.read();
		let incorrectly_checked = current_lock
			.answers
			.iter()
			.filter(|a| !a.is_correct.unwrap_or_default() && a.checked)
			.count();
		let correctly_checked = current_lock
			.answers
			.iter()
			.filter(|a| a.is_correct.unwrap_or_default() && a.checked)
			.count();

		correctly_checked.saturating_sub(incorrectly_checked)
	});

	let total_questions = get_questions().len();
	let current_question = use_memo(move || questions().len());
	let left_questions = use_memo(move || total_questions - current_question());
	let mut correct_questions = use_signal(|| 0);
	let mut wrong_questions = use_signal(|| 0);

	let mut correct_animation = use_signal(|| false);
	let mut wrong_animation = use_signal(|| false);

	use_future(move || async move {
		loop {
			tokio::time::sleep(Duration::from_millis(400)).await;
			let is_correct = correct_animation();
			let is_wrong = wrong_animation();
			if is_correct || is_wrong {
				tokio::time::sleep(Duration::from_millis(600)).await;

				// Uncheck all the answers
				current().answers.iter_mut().for_each(|a| a.checked = false);

				let mut correct_questions_lock = correct_questions.write();
				let mut wrong_questions_lock = wrong_questions.write();

				// Get a new question or reroll the list
				if !questions().is_empty() {
					current.set(questions.remove(0));

					// Update the correct/wrong counters
					if is_correct {
						*correct_questions_lock += 1;
					} else if is_wrong {
						*wrong_questions_lock += 1;
					}
				} else {
					questions.set(get_rand_questions());
					current.set(questions.remove(0));

					*correct_questions_lock = 0;
					*wrong_questions_lock = 0;
				}

				// Reset animation flags
				correct_animation.set(false);
				wrong_animation.set(false);
			}
		}
	});

	let answer_buttons = current()
		.answers
		.into_iter()
		.enumerate()
		.map(|(i, _answer)| {
			rsx! {
				AnswerCheckbox { current, id: i }
			}
		});

	rsx! {
		ResultPopup { is_correct: correct_animation, is_wrong: wrong_animation },
		div {
			id: "counter",
			div { "{left_questions}" }
			div {
				class: "correct",
				"{correct_questions}"
			}
			div {
				class: "wrong",
				"{wrong_questions}"
			}
			div { "{total_questions}" }
		},
		form {
			id: "form",
			onsubmit: move |_| {
				if actual_correct() == total_correct() {
					correct_animation.set(true);
				}
				else {
					wrong_animation.set(true);
				}
			},

			h1 {
				class: if correct_animation() { "correct" },
				class: if wrong_animation() { "wrong" },
				"{current().message}"
			}
			{ answer_buttons }
			input {
				type: "submit",
			}
		}
	}
}

#[component]
pub fn AnswerCheckbox(current: Signal<Question>, id: usize) -> Element {
	let message = use_memo(move || {
		current
			.read()
			.answers
			.get(id)
			.map(|a| a.message.clone())
			.unwrap_or("???".to_string())
	});

	let checked = use_memo(move || {
		current
			.read()
			.answers
			.get(id)
			.map(|a| a.checked)
			.unwrap_or(false)
	});

	rsx! {
		div {
			class: if checked() { "selected" },
			onclick: move |_| {
				let mut write_lock = current.write();
				if let Some(answer) = write_lock.answers.get_mut(id) {
					answer.checked = !answer.checked;
				}
			},

			input {
				id: "a{id}",
				name: "a{id}",
				type: "checkbox",
				value: "{id}",
				checked: "{checked}",
				onclick: move |event| event.prevent_default(),
			}
			label {
				for: "a{id}",
				onclick: move |event| event.prevent_default(),
				"{message}"
			},
		}
	}
}

#[component]
pub fn ResultPopup(is_correct: Signal<bool>, is_wrong: Signal<bool>) -> Element {
	let is_correct = use_memo(move || is_correct());
	let is_wrong = use_memo(move || is_wrong());
	let is_visible = use_memo(move || is_correct() || is_wrong());

	rsx! {
		div {
			id: "result",
			class: if is_visible() { "visible" },
			class: if is_correct() { "correct" },
			class: if is_wrong() { "wrong" },
			if is_correct() { "✓" } else { "X" }
		}
	}
}