use iced::Space;
use iced_native::text_input::Value;
use core::ops::RangeInclusive;
use core::time::Duration;
use iced::Row;
use iced::Text;
use iced::Container;
use iced::Length;
use iced::Element;
use crate::styles::{Theme, FONT_VG5000};
use crate::app::Message;

use iced::widget::text_input::{self, TextInput};
use iced::widget::scrollable::{self, Scrollable};
use iced::Align;
use iced_native::widget::text_input::cursor::State;

#[derive(Debug, Clone, PartialEq, Eq)]
pub enum LyricEvent {
	LyricChanged(String),
	TimestampChanged(String),
	LineAdvanced,
}

impl LyricEvent {
	fn into_msg(self, line_no: usize) -> Message {
		Message::LyricEvent {
			kind: self,
			line_no,
		}
	}
}

pub struct Lyrics {
	lines: Vec<Lyric>,
	scroll_state: scrollable::State,
}

impl Lyrics {
	pub fn new() -> Lyrics {
		let mut lyric = Lyric::new();
		lyric.select();

		Self {
			lines: vec![lyric],
			scroll_state: scrollable::State::new(),
		}
	}

	pub fn insert_text(&mut self, text: String) {

		let mut pieces = text.trim_end()
			.split('\n')
			.map(str::trim);

		let (line_no, current_line) = self.current_line_mut();

		current_line.deselect();
		current_line.value.push_str(pieces.next().unwrap());

		let pieces = pieces
			.collect::<Vec<_>>()
			.into_iter()
			.map(str::to_owned)
			.map(Lyric::new_with_value);
		let n_pieces = pieces.size_hint().0;

		self.lines.splice((line_no + 1)..(line_no + 1), pieces);

		self.lines[line_no + n_pieces].select();
	}

	pub fn handle_event(&mut self, line_no: usize, kind: LyricEvent) {
		match kind {
			LyricEvent::LyricChanged(newval) => {
				self.update_line(newval, line_no)
			},
			LyricEvent::TimestampChanged(newval) => {
				self.lines[line_no].timestamp_update(newval)
			},
			LyricEvent::LineAdvanced => {
				self.advance_line(line_no)
			},
		}
	}

	pub fn update_line(&mut self, new_content: String, line_no: usize) {
		self.lines[line_no].value = new_content;
	}

	pub fn advance_line(&mut self, current_line: usize) {
		let new_line = current_line + 1;

		let line = if new_line == self.lines.len() {
			self.insert_line(new_line, None)
		} else {
			self.lines.get_mut(new_line)
				.expect("Unexpected .advance_line with index beyond # of lines")
		};

		line.select();

		self.lines.get_mut(current_line)
			.unwrap()
			.deselect();
	}

	pub fn insert_line(&mut self, index: usize, content: Option<String>) -> &mut Lyric {
		self.lines.insert(index, match content {
			Some(content) => Lyric::new_with_value(content),
			None => Lyric::new(),
		});
		self.lines.get_mut(index).unwrap()
	}

	pub fn current_line_mut(&mut self) -> (usize, &mut Lyric) {
		self.lines
			.iter_mut()
			.enumerate()
			.find(|(_, l)| l.is_selected())
			.expect("no line currently selected")
	}

	pub fn view(&mut self, theme: Theme) -> Element<Message> {
		let is_sole_line = self.lines.len() == 1;
		let spacers = (
			Space::new(Length::Fill, Length::Units(30)),
			Space::new(Length::Fill, Length::Units(30)),
		);

		let scroller = self.lines.iter_mut()
			.enumerate()
			.map(|(i, l)| l.view(is_sole_line, i, theme))
			.fold(Scrollable::new(&mut self.scroll_state).push(spacers.0), |s, l| s.push(l))
			.push(spacers.1)
			.width(Length::Fill)
			.align_items(Align::Center);

		Container::new(scroller)
			.height(Length::Fill)
			.width(Length::Fill)
			.center_y()
			.into()
	}
}


#[derive(Clone, Debug)]
pub struct Lyric {
	main_state: text_input::State,
	timestamp_state: text_input::State,
	pub value: String,
	pub timestamp: Duration,
	timestamp_raw: String,
}

impl Lyric {
	pub fn new() -> Self {
		Self::new_with_value(String::with_capacity(70))
	}

	pub fn new_with_value(val: String) -> Self {
		Lyric {
			main_state: text_input::State::new(),
			timestamp_state: text_input::State::new(),
			timestamp: Duration::ZERO,
			timestamp_raw: String::from("0:00.000"),
			value: val,
		}
	}

	pub fn view(&mut self, show_placeholder: bool, line_no: usize, theme: Theme) -> Element<Message> {

		const SMALL_SIZE: u16 = 20;
		const LARGE_SIZE: u16 = 25;
		const TIMESTAMP_W: u16 = 67;
		const LINE_HEIGHT: u16 = 26;
		const TOTAL_W: u16 = 400;

		let is_focused = self.is_selected();

		let placeholder = if show_placeholder {
			"Paste some lyrics to get started"
		} else if is_focused {
			"..."
		} else { "" };

		let size = if is_focused { LARGE_SIZE } else { SMALL_SIZE };

		let timestamp_input = TextInput::new(
			&mut self.timestamp_state,
			"",
			&self.timestamp_raw,
			move|new_value| LyricEvent::TimestampChanged(new_value).into_msg(line_no),
		)
			.style(theme)
			.size(SMALL_SIZE)
			.width(Length::Units(TIMESTAMP_W))
			.on_submit(LyricEvent::LineAdvanced.into_msg(line_no))
			.font(FONT_VG5000)
			.into();

		let text_input = TextInput::new(
			&mut self.main_state,
			placeholder,
			&self.value,
			move|new_value| LyricEvent::LyricChanged(new_value).into_msg(line_no),
		)
			.style(theme.active_lyric(is_focused))
			.size(size)
			.width(Length::Fill)
			.on_submit(LyricEvent::LineAdvanced.into_msg(line_no))
			.font(FONT_VG5000)
			.into();

		let l_bracket = Text::new("[")
			.size(SMALL_SIZE)
			.color(theme.reduced_text_color())
			.font(FONT_VG5000)
			.into();
		let r_bracket = Text::new("]  ")
			.size(SMALL_SIZE)
			.color(theme.reduced_text_color())
			.font(FONT_VG5000)
			.into();

		Row::with_children(vec![l_bracket, timestamp_input, r_bracket, text_input])
			.width(Length::Units(TOTAL_W))
			.height(Length::Units(LINE_HEIGHT))
			.align_items(Align::Center)
			.into()
	}

	pub fn select(&mut self) {
		self.main_state.focus();
		self.main_state.move_cursor_to_end();
	}

	pub fn is_selected(&self) -> bool {
		self.main_state.is_focused() || self.timestamp_state.is_focused()
	}

	pub fn deselect(&mut self) {
		self.main_state.unfocus();
		self.timestamp_state.unfocus();
	}

	pub (crate) fn timestamp_update(&mut self, newval: String) {
		if let Some((shift, validated)) = Self::clean_timestamp(newval) {
			self.timestamp = dbg!(Self::parse_validated_timestamp(&validated));
			self.timestamp_raw = validated;
			if shift != 0 {
				self.timestamp_state.move_cursor_to(
					match self.timestamp_state.cursor().state(&Value::new(&self.timestamp_raw)) {
						State::Index(p) => ((p as isize) + shift) as usize,
						State::Selection { start, ..} => {
							// Should be impossible, but lets handle it anyway
							((start as isize) + shift) as usize
						},
					}
				);
			}
		}
	}

	fn clean_timestamp(mut raw: String) -> Option<(isize, String)> {
		// Rules:
		// - [R0] Must have exactly 1 colon (:)
		// - [R1] Must have exactly 1 period (.)
		// - [R2] The period must follow the colon
		// - [R3] No characters outside 0-9, colon, and period
		// - [R4] Unnecessary leading zeros besides normal padding are trimmed
		// - [R5] Each section is padded to the appropriate length (reversed for millis)
		const VALID_CHARS: RangeInclusive<char> = '0'..=':';
		const MIN_DIGIT_COUNTS: [usize; 3] = [1, 2, 3];
		let mut colon_count = 0;
		let mut period_count = 0;
		let mut digit_counts = [0; 3];
		for c in raw.chars() {
			match c {
				':' => {
					colon_count += 1;
					if colon_count > 1 {
						return None; // Rejected [R0]
					}
				},
				'.' => {
					period_count += 1;
					if colon_count == 0 /* [R2] */ || period_count > 1 /* [R1] */ {
						return None; // Rejected
					}
				},
				_ if VALID_CHARS.contains(&c) || c == '.' => {
					let section = colon_count + period_count;
					digit_counts[section] += 1;
				},
				_ => {
					return None; // Rejected [R3]
				}
			}
		}

		if period_count == 0 {
			return None; //Rejected [R1]
		}

		let mut i = 0;
		let mut cursor_shift = 0;
		for section in 0..3 {
			while digit_counts[section] < MIN_DIGIT_COUNTS[section] {
				// [R5]
				if section == 2 {
					raw.push('0');
				} else {
					raw.insert(i, '0');
					cursor_shift += 1;
				}
				digit_counts[section] += 1;
			}

			while
				digit_counts[section] > MIN_DIGIT_COUNTS[section]
				&& if section == 2 {
					raw.ends_with('0')
				} else {
					raw.chars().nth(i).unwrap() == '0'
				}
			{
				// [R4]
				if section == 2 {
					raw.truncate(raw.len() - 1);
				} else {
					raw.remove(i);
					cursor_shift -= 1;
				}
				digit_counts[section] -= 1;
			}

			i += digit_counts[section] + 1;
		}

		Some((cursor_shift, raw))
	}

	fn parse_validated_timestamp(s: &str) -> Duration {
		let (minutes, s) = s.split_at(s.find(':').expect(
			"parse_validated_timestamp received a timestamp without a :"
		));
		let (seconds, millis) = s.split_at(s.find('.').expect(
			"parse_validated_timestamp received a timestamp without a . after the :"
		));

		let minutes: u64 = minutes.parse()
			.expect("parse_validated_timestamp received an invalid number of minutes");
		let seconds: u64 = seconds[1..].parse()
			.expect("parse_validated_timestamp received an invalid number of seconds");
		let millis: u32 = millis[1..4].parse()
			.expect("parse_validated_timestamp received an invalid number of millis");

		Duration::new(seconds + minutes * 60, millis * 1_000_000)
	}
}