use std::collections::HashMap;

use raylib::{drawing::RaylibDrawHandle, math::Vector2, texture::Texture2D};

mod board;
mod tile;
use board::{Board, Pos};
use tile::*;

#[derive(Debug)]
pub struct Machine {
	board: Board,
	marbles: Vec<Pos>,

	input: Vec<u8>,
	input_index: usize,
	output: Vec<u8>,
	steps: usize,
}

impl Machine {
	pub fn new_empty(width: usize) -> Self {
		Self {
			board: Board::new_empty(width, width),
			marbles: Vec::new(),
			input: Vec::new(),
			input_index: 0,
			output: Vec::new(),
			steps: 0,
		}
	}

	pub fn new(grid: Board, input: Vec<u8>) -> Self {
		// let (grid, marbles) = parse(source);
		let mut marbles = Vec::new();
		for y in 0..grid.height() {
			for x in 0..grid.width() {
				if let Some(Tile::Marble { value: _, dir: _ }) = grid.get((x, y).into()) {
					marbles.push((x, y).into());
				}
			}
		}
		Self {
			board: grid,
			marbles,
			input,
			input_index: 0,
			output: Vec::new(),
			steps: 0,
		}
	}

	pub fn draw(
		&self,
		d: &mut RaylibDrawHandle,
		textures: &HashMap<String, Texture2D>,
		offset: Vector2,
	) {
		let tile_size = 32;
		for x in 0..self.board.width() {
			for y in 0..self.board.height() {
				if let Some(tile) = self.board.get((x, y).into()) {
					let px = x as i32 * tile_size + offset.x as i32 + tile_size / 2;
					let py = y as i32 * tile_size + offset.y as i32 + tile_size / 2;
					tile.draw(d, textures, px, py, tile_size);
				}
			}
		}
	}

	pub fn step(&mut self) {
		self.steps += 1;
		// reset wires
		for y in 0..self.board.height() {
			for x in 0..self.board.width() {
				if let Tile::Powerable(_, state) = self.board.get_mut((x, y).into()) {
					*state = false;
				}
			}
		}
		let mut to_remove = Vec::new();
		let mut triggers = Vec::new();
		for i in 0..self.marbles.len() {
			let marble_pos = self.marbles[i];
			let tile = self.board.get_or_blank(marble_pos);

			if let Tile::Marble { value, dir } = tile {
				let next_pos = dir.step(marble_pos);
				if !self.board.in_bounds(next_pos) {
					continue;
				}
				let mut new_tile = None;
				let target = self.board.get_mut(next_pos);
				match target {
					Tile::Blank => {
						*target = tile;
						self.marbles[i] = next_pos;
						new_tile = Some(Tile::Blank);
					}
					Tile::Digit(d) => {
						let new_val = value
							.wrapping_mul(10)
							.wrapping_add((*d - b'0') as MarbleValue);
						*target = Tile::Marble {
							value: new_val,
							dir,
						};
						self.marbles[i] = next_pos;
						new_tile = Some(Tile::Blank);
					}
					Tile::Powerable(PTile::Bag, _) => {
						to_remove.push(i);
						new_tile = Some(Tile::Blank);
					}
					Tile::Marble {
						value: _other_value,
						dir: other_dir,
					} => {
						// bounce off other marbles
						if *other_dir != dir {
							new_tile = Some(Tile::Marble {
								value,
								dir: dir.opposite(),
							});
							*other_dir = dir;
						}
					}
					Tile::Powerable(PTile::Trigger, state) => {
						*state = true;
						triggers.push(next_pos);
						let far_pos = dir.step(next_pos);
						if let Some(Tile::Blank) = self.board.get(far_pos) {
							self.board.set(far_pos, Tile::Marble { value, dir });
							self.marbles[i] = far_pos;
							new_tile = Some(Tile::Blank);
						}
					}
					Tile::Arrow(arrow_dir) => {
						let far_pos = arrow_dir.step(next_pos);
						let arrow_dir = *arrow_dir;
						if let Some(Tile::Blank) = self.board.get(far_pos) {
							self.marbles[i] = far_pos;
							self.board.set(
								far_pos,
								Tile::Marble {
									value,
									dir: arrow_dir,
								},
							);
							new_tile = Some(Tile::Blank);
						} else if far_pos == marble_pos {
							// bounce on reverse arrow
							new_tile = Some(Tile::Marble {
								value,
								dir: dir.opposite(),
							});
						}
					}
					Tile::Mirror(mirror) => {
						let new_dir = mirror.new_dir(dir);
						let far_pos = new_dir.step(next_pos);
						let far_target = self.board.get_mut(far_pos);
						if let Tile::Blank = far_target {
							*far_target = Tile::Marble {
								value,
								dir: new_dir,
							};
							self.marbles[i] = far_pos;
							new_tile = Some(Tile::Blank);
						}
					}
					_ => (),
				}

				if let Some(t) = new_tile {
					*self.board.get_mut(marble_pos) = t;
				}
			}
		}
		let mut offset = 0;
		for i in to_remove {
			self.marbles.remove(i - offset);
			offset += 1;
		}
		for pos in triggers {
			for dir in Direction::ALL {
				self.propagate_power(dir, dir.step(pos));
			}
		}
	}

	fn propagate_power(&mut self, dir: Direction, pos: Pos) {
		if !self.board.in_bounds(pos) {
			return;
		}
		let tile = self.board.get_mut(pos);
		let front_pos = dir.step(pos);
		if let Tile::Powerable(tile, state) = tile {
			if let PTile::Trigger = tile {
				return;
			}
			if *state {
				return;
			}
			*state = true;
			match tile {
				PTile::Wire(wiretype) => {
					let dirs = wiretype.directions();
					for d in dirs {
						self.propagate_power(*d, d.step(pos));
					}
				}
				PTile::Output => {
					let sample = self.board.get_or_blank(front_pos);
					if let Tile::Marble { value, dir: _ } = sample {
						self.output.push(value as u8);
					}
				}
				PTile::Bag => {
					if let Some(Tile::Blank) = self.board.get(front_pos) {
						*self.board.get_mut(front_pos) = Tile::Marble { value: 0, dir };
						self.marbles.push(front_pos);
					}
				}
				PTile::Input => {
					if self.input_index < self.input.len()
						&& self.board.get_or_blank(front_pos).is_blank()
					{
						let value = self.input[self.input_index] as MarbleValue;
						*self.board.get_mut(front_pos) = Tile::Marble { value, dir };
						self.marbles.push(front_pos);
						self.input_index += 1;
					}
				}
				PTile::Math(op) => {
					let op = *op;
					let pos_a = dir.left().step(pos);
					let pos_b = dir.right().step(pos);
					let val_a = self.board.get_or_blank(pos_a).read_value();
					let val_b = self.board.get_or_blank(pos_b).read_value();
					if (!self.board.get_or_blank(pos_a).is_blank()
						|| !self.board.get_or_blank(pos_b).is_blank())
						&& self.board.get_or_blank(front_pos).is_blank()
					{
						let result = match op {
							MathOp::Add => val_a.wrapping_add(val_b),
							MathOp::Sub => val_a.wrapping_sub(val_b),
							MathOp::Mul => val_a.wrapping_mul(val_b),
							MathOp::Div => val_a.checked_div(val_b).unwrap_or_default(),
							MathOp::Rem => val_a.checked_rem(val_b).unwrap_or_default(),
						};
						// println!("{op:?} a:{val_a} b:{val_b}");
						*self.board.get_mut(front_pos) = Tile::Marble { value: result, dir };
						self.marbles.push(front_pos);
					}
				}
				PTile::Flipper => {
					let m = self.board.get_mut(front_pos);
					match m {
						Tile::Powerable(PTile::Wire(wire_type), _) => {
							*wire_type = match *wire_type {
								WireType::Vertical => WireType::Horizontal,
								WireType::Horizontal => WireType::Vertical,
								WireType::Cross => WireType::Cross,
							};
						}
						Tile::Mirror(mirror) => {
							*mirror = match *mirror {
								MirrorType::Forward => MirrorType::Back,
								MirrorType::Back => MirrorType::Forward,
							};
						}
						Tile::Arrow(dir) => {
							*dir = dir.opposite();
						}
						_ => (),
					};
				}
				PTile::Gate(gate) => {
					let gate = *gate;
					let pos_a = dir.left().step(pos);
					let pos_b = dir.right().step(pos);
					let val_a = self.board.get_or_blank(pos_a).read_value();
					let val_b = self.board.get_or_blank(pos_b).read_value();

					let result = match gate {
						GateType::LessThan => val_a < val_b,
						GateType::GreaterThan => val_a > val_b,
						GateType::Equal => val_a == val_b,
						GateType::NotEqual => val_a != val_b,
					};
					if result {
						self.propagate_power(dir, dir.step(pos));
					}
				}
				PTile::Trigger => (),
			}
		}
	}
}

pub fn parse(source: &str) -> Board {
	let mut rows = Vec::new();

	let mut width = 0;
	for line in source.lines() {
		width = width.max(line.len());
		let mut tiles = Vec::new();
		let mut in_comment = false;
		for char in line.chars() {
			if in_comment {
				if char == ')' {
					in_comment = false;
				}
				if char == ' ' {
					// allow marbles to pass through gaps in comments
					tiles.push(Tile::Blank);
				} else {
					tiles.push(Tile::Comment(char as u8));
				}
				continue;
			}
			tiles.push(match char {
				'o' => Tile::Marble {
					value: 0,
					dir: Direction::Down,
				},
				'*' => Tile::Powerable(PTile::Trigger, false),
				'-' => Tile::Powerable(PTile::Wire(WireType::Horizontal), false),
				'|' => Tile::Powerable(PTile::Wire(WireType::Vertical), false),
				'+' => Tile::Powerable(PTile::Wire(WireType::Cross), false),
				'/' => Tile::Mirror(MirrorType::Forward),
				'\\' => Tile::Mirror(MirrorType::Back),
				'^' => Tile::Arrow(Direction::Up),
				'v' => Tile::Arrow(Direction::Down),
				'<' => Tile::Arrow(Direction::Left),
				'>' => Tile::Arrow(Direction::Right),
				'=' => Tile::Powerable(PTile::Gate(GateType::Equal), false),
				'!' => Tile::Powerable(PTile::Gate(GateType::NotEqual), false),
				'L' => Tile::Powerable(PTile::Gate(GateType::LessThan), false),
				'G' => Tile::Powerable(PTile::Gate(GateType::GreaterThan), false),
				'P' => Tile::Powerable(PTile::Output, false),
				'I' => Tile::Powerable(PTile::Input, false),
				'F' => Tile::Powerable(PTile::Flipper, false),
				'A' => Tile::Powerable(PTile::Math(MathOp::Add), false),
				'S' => Tile::Powerable(PTile::Math(MathOp::Sub), false),
				'M' => Tile::Powerable(PTile::Math(MathOp::Mul), false),
				'D' => Tile::Powerable(PTile::Math(MathOp::Div), false),
				'R' => Tile::Powerable(PTile::Math(MathOp::Rem), false),
				'B' => Tile::Powerable(PTile::Bag, false),
				d @ '0'..='9' => Tile::Digit(d as u8),
				'#' => Tile::Block,
				' ' => Tile::Blank,
				'(' => {
					in_comment = true;
					Tile::Comment(b'(')
				}
				_ => Tile::Blank,
			});
		}
		rows.push(tiles);
	}
	for line in &mut rows {
		line.resize(width, Tile::Blank);
	}

	Board::new(rows)
}