use raylib::prelude::*;

pub mod board;
pub mod pos;
pub mod tile;
use board::Board;
use pos::*;
use tile::*;

use crate::{ui::draw_usize_small, Textures, TILE_TEXTURE_SIZE};

#[derive(Debug)]
pub struct Machine {
	board: Board,
	marbles: Vec<Pos>,
	powered: Vec<Pos>,
	input: Vec<u8>,
	input_index: usize,
	output: Vec<u8>,
	steps: usize,
}

impl Machine {
	pub fn new_empty() -> Self {
		Self {
			board: Board::new_empty(5, 5),
			marbles: Vec::new(),
			powered: Vec::new(),
			input: Vec::new(),
			input_index: 0,
			output: Vec::new(),
			steps: 0,
		}
	}

	pub fn reset(&mut self) {
		self.steps = 0;
		self.input_index = 0;
		self.output.clear();
		self.powered.clear();
	}

	pub fn set_board(&mut self, board: Board) {
		self.marbles = board.get_marbles();
		self.powered.clear();
		self.board = board;
	}

	pub fn board(&self) -> &Board {
		&self.board
	}

	pub fn output(&self) -> &[u8] {
		&self.output
	}

	pub fn input(&self) -> &[u8] {
		&self.input
	}

	pub fn input_index(&self) -> usize {
		self.input_index
	}

	pub fn step_count(&self) -> usize {
		self.steps
	}

	pub fn set_input(&mut self, bytes: Vec<u8>) {
		self.input_index = self.input_index.min(bytes.len());
		self.input = bytes;
	}

	pub fn draw_marble_values(
		&self,
		d: &mut RaylibDrawHandle,
		textures: &Textures,
		offset: Vector2,
		scale: f32,
	) {
		let tile_size = (TILE_TEXTURE_SIZE * scale) as i32;
		for marble in &self.marbles {
			let x = marble.x;
			let y = marble.y;
			if let Some(tile) = self.board.get(*marble) {
				let px = x as i32 * tile_size + offset.x as i32;
				let py = y as i32 * tile_size + offset.y as i32;
				if let Tile::Marble { value, dir } = tile {
					let texture = textures.get(dir.arrow_texture_name());
					let pos = Vector2::new(px as f32, py as f32);
					let faded_white = Color::new(255, 255, 255, 100);
					d.draw_texture_ex(texture, pos, 0., scale, faded_white);
					draw_usize_small(d, textures, value as usize, px, py, scale);
				}
			}
		}
	}

	pub fn step(&mut self) {
		self.steps += 1;

		let old_marbles = self.marbles.len();

		let mut new_marbles = Vec::new();
		// activate all powered machines
		for &pos in &self.powered {
			match self.board.get_mut(pos) {
				Some(Tile::Powerable(machine, state)) => {
					*state = false;
					let machine = *machine;
					for dir in Direction::ALL {
						let front_pos = dir.step(pos);
						let source_pos = dir.opposite().step(pos);
						match self.board.get(source_pos) {
							Some(Tile::Wire(wiretype, true)) => {
								if !wiretype.has_output(dir) {
									continue;
								}
							}
							Some(Tile::Button(true)) => (),
							_ => continue,
						}
						let Some(front_tile) = self.board.get_mut(front_pos) else {
							continue;
						};
						// `machine`` is being powered, in direction `dir``
						match machine {
							PTile::Comparator(_) => (), // handled at the power propagation stage (end of step)
							PTile::Math(op) => {
								if front_tile.is_blank() {
									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 value = 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(),
									};
									new_marbles.push((front_pos, value, dir));
								}
							}
							PTile::IO => {
								if front_tile == &Tile::BLANK && self.input_index < self.input.len()
								{
									let value = self.input[self.input_index] as MarbleValue;
									self.input_index += 1;
									new_marbles.push((front_pos, value, dir));
								}
							}
							PTile::Silo => {
								if front_tile == &Tile::BLANK {
									new_marbles.push((front_pos, 0, dir));
								}
							}
							PTile::Flipper => {
								match front_tile {
									Tile::Wire(wire_type, _) => {
										*wire_type = match *wire_type {
											WireType::Vertical => WireType::Horizontal,
											WireType::Horizontal => WireType::Vertical,
											WireType::Cross => WireType::Cross,
										}
									}
									Tile::Mirror(mirror) => mirror.flip(),
									Tile::Arrow(dir) => *dir = dir.opposite(),
									_ => (),
								};
							}
						}
					}
				}
				Some(Tile::Button(_state)) => (),
				Some(Tile::Wire(_, _state)) => (),
				_ => unreachable!(),
			};
		}

		// old wires have to be reset after machine processing,
		// so they can figure out which directions they are powered from
		for &p in &self.powered {
			match self.board.get_mut(p) {
				Some(Tile::Button(state)) => *state = false,
				Some(Tile::Wire(_, state)) => *state = false,
				_ => (),
			}
		}
		self.powered.clear();

		if self.marbles.is_empty() {
			return;
		}

		#[derive(Clone, Copy, Debug)]
		enum DirInfluence {
			None,
			One(Direction),
			Multiple,
		}

		// #### find all direct bounces ####
		let mut will_reverse_direction = vec![false; self.marbles.len()];
		// todo store in tile to remove search through self.marbles
		let mut influenced_direction = vec![DirInfluence::None; self.marbles.len()];

		for (i, &pos) in self.marbles.iter().enumerate() {
			let Some(Tile::Marble { value: _, dir }) = self.board.get(pos) else {
				unreachable!()
			};
			let front_pos = dir.step(pos);
			let Some(front_tile) = self.board.get(front_pos) else {
				continue;
			};
			match front_tile {
				Tile::Marble {
					value: _,
					dir: other_dir,
				} => {
					if other_dir != dir {
						// this marble is facing another marble, and will therefore definitely bounce
						will_reverse_direction[i] = true;
						// the other marble will bounce too, either
						let other_index =
							self.marbles.iter().position(|m| *m == front_pos).unwrap();
						let influence = &mut influenced_direction[other_index];
						*influence = match *influence {
							DirInfluence::None => DirInfluence::One(dir),
							DirInfluence::One(_) => DirInfluence::Multiple,
							DirInfluence::Multiple => DirInfluence::Multiple,
						}
					}
				}
				Tile::Arrow(arrow_dir) => {
					if arrow_dir == dir.opposite() {
						// bounce on a reverse facing arrow
						will_reverse_direction[i] = true;
					}
				}
				_ => (),
			}
		}
		// #### apply all direct bounces ####
		for (i, &pos) in self.marbles.iter().enumerate() {
			let Some(Tile::Marble { value: _, dir }) = self.board.get_mut(pos) else {
				unreachable!()
			};
			if will_reverse_direction[i] {
				*dir = dir.opposite();
			} else if let DirInfluence::One(new_dir) = influenced_direction[i] {
				*dir = new_dir;
			}
		}

		// #### new marbles ####
		let mut claim_positions = Vec::new();
		// prepare creating the new marbles
		for &(pos, _val, _dir) in &new_marbles {
			let Some(Tile::Open(OpenTile::Blank, claim)) = self.board.get_mut(pos) else {
				unreachable!()
			};
			if claim.claim_indirect() {
				claim_positions.push(pos);
			}
		}
		// create new marbles
		// new marbles are past old_marbles index, so will not move this step
		for (pos, value, dir) in new_marbles {
			let Some(Tile::Open(OpenTile::Blank, Claim::ClaimedIndirect)) = self.board.get_mut(pos) else {
				continue;
			};
			self.board.set(pos, Tile::Marble { value, dir });
			self.marbles.push(pos);
		}

		// #### movement ####
		// mark claims to figure out what spaces can be moved to
		for &pos in &self.marbles[..old_marbles] {
			let Some(Tile::Marble { value: _, dir }) = self.board.get(pos) else {
				unreachable!()
			};
			let front_pos = dir.step(pos);
			let Some(front_tile) = self.board.get_mut(front_pos) else {
				continue;
			};
			if let Tile::Open(_type, claim) = front_tile {
				if claim.claim() {
					claim_positions.push(front_pos);
				}
			} else {
				let target_pos = match front_tile {
					Tile::Arrow(d) => d.step(front_pos),
					Tile::Mirror(m) => m.new_dir(dir).step(front_pos),
					Tile::Button(_) => dir.step(front_pos),
					_ => continue,
				};
				let Some(target_tile) = self.board.get_mut(target_pos) else {
					continue;
				};
				if let Tile::Open(_type, claim) = target_tile {
					if claim.claim_indirect() {
						claim_positions.push(front_pos);
					}
				}
			}
		}

		let mut removed_marbles = Vec::new();
		// move marbles
		for (i, pos) in self.marbles[..old_marbles].iter_mut().enumerate() {
			let Some(Tile::Marble { value, dir }) = self.board.get(*pos) else {
				unreachable!()
			};
			let front_pos = dir.step(*pos);
			let Some(front_tile) = self.board.get_mut(front_pos) else {
				continue;
			};

			let mut move_to = |tile, target_pos, dir, board: &mut Board| {
				let value = match tile {
					OpenTile::Blank => value,
					OpenTile::Digit(n) => value.wrapping_mul(10).wrapping_add(n as MarbleValue),
				};
				board.set(*pos, Tile::BLANK);
				board.set(target_pos, Tile::Marble { value, dir });
				*pos = target_pos;
			};

			if let Tile::Open(space_type, claim_state) = front_tile {
				if *claim_state == Claim::Claimed {
					move_to(*space_type, front_pos, dir, &mut self.board);
				} else if *claim_state != Claim::Free {
					// (Free means a marble was just here but moved earlier this tick)
					// bounce on failed direct movement
					self.board.set(
						*pos,
						Tile::Marble {
							value,
							dir: dir.opposite(),
						},
					);
				}
			} else {
				let target_pos;
				let mut is_button = false;
				let mut new_dir = dir;
				match front_tile {
					Tile::Arrow(d) => {
						target_pos = d.step(front_pos);
						new_dir = *d;
					}
					Tile::Mirror(m) => {
						new_dir = m.new_dir(dir);
						target_pos = new_dir.step(front_pos);
					}
					Tile::Button(_) => {
						is_button = true;
						target_pos = dir.step(front_pos);
					}
					Tile::Powerable(PTile::Silo, _) => {
						removed_marbles.push(i);
						continue;
					}
					Tile::Powerable(PTile::IO, _) => {
						removed_marbles.push(i);
						self.output.push(value as u8);
						continue;
					}
					_ => continue,
				}
				let Some(target_tile) = self.board.get_mut(target_pos) else {
					continue;
				};
				if let Tile::Open(space_type, Claim::ClaimedIndirect) = target_tile {
					move_to(*space_type, target_pos, new_dir, &mut self.board);
					if is_button {
						self.powered.push(front_pos);
					}
				}
			}
		}

		for pos in claim_positions {
			if let Some(Tile::Open(_, claim_state)) = self.board.get_mut(pos) {
				*claim_state = Claim::Free;
			}
		}

		// remove marbles
		for &i in removed_marbles.iter().rev() {
			self.board.set(self.marbles[i], Tile::BLANK);
			self.marbles.swap_remove(i);
		}

		// propagate power
		let mut i = 0;
		while i < self.powered.len() {
			let pos = self.powered[i];
			let Some(tile) = self.board.get_mut(pos) else {
				unreachable!()
			};
			match tile {
				Tile::Button(state) => {
					*state = true;
					for dir in Direction::ALL {
						let target_pos = dir.step(pos);
						match self.board.get_mut(target_pos) {
							Some(Tile::Powerable(_, state)) => {
								if !*state {
									*state = true;
									self.powered.push(target_pos);
								}
							}
							Some(Tile::Wire(_, state)) => {
								// only push it if it hasnt already been pushed
								if !*state {
									*state = true;
									self.powered.push(target_pos);
								}
							}
							_ => (),
						}
					}
				}
				Tile::Wire(wiretype, state) => {
					*state = true;
					for dir in wiretype.directions() {
						let target_pos = dir.step(pos);
						match self.board.get_mut(target_pos) {
							Some(Tile::Powerable(_, state)) => {
								if !*state {
									*state = true;
									self.powered.push(target_pos);
								}
							}
							Some(Tile::Wire(_, state)) => {
								// only push it if it hasnt already been pushed
								if !*state {
									*state = true;
									self.powered.push(target_pos);
								}
							}
							_ => (),
						}
					}
				}
				Tile::Powerable(PTile::Comparator(comp), state) => {
					*state = true;
					let comp = *comp;
					for dir in Direction::ALL {
						let front_pos = dir.step(pos);
						let source_pos = dir.opposite().step(pos);
						match self.board.get(source_pos) {
							Some(Tile::Wire(wiretype, true)) => {
								if !wiretype.has_output(dir) {
									continue;
								}
							}
							Some(Tile::Button(true)) => (),
							_ => continue,
						}
						let Some(front_tile) = self.board.get_mut(front_pos) else {
							continue;
						};
						if matches!(front_tile, Tile::Wire(_, _) | Tile::Powerable(_, _)) {
							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 comp {
								Comparison::LessThan => val_a < val_b,
								Comparison::GreaterThan => val_a > val_b,
								Comparison::Equal => val_a == val_b,
								Comparison::NotEqual => val_a != val_b,
							};
							if result {
								self.powered.push(front_pos);
							}
						}
					}
				}
				// state may be false if it was powered by a machine in earlier step
				Tile::Powerable(_, state) => *state = true,
				_ => {
					dbg!(tile);
					unreachable!()
				}
			}
			i += 1;
		}
	}
}