#![allow(unused_imports)]
#![allow(unused_variables)]
#![allow(unused_mut)]
#![allow(dead_code)]

use rand::Rng;
use std::cmp;
use tcod::colors::*;
use tcod::console::*;
use tcod::input::{self, Event, Key, Mouse};
use tcod::map::{FovAlgorithm, Map as FovMap};

const SCREEN_WIDTH: i32 = 80;
const SCREEN_HEIGHT: i32 = 50;
const FPS: i32 = 20;
const MAP_WIDTH: i32 = 80;
const MAP_HEIGHT: i32 = 43;
const COLOR_DARK_WALL: Color = Color { r: 0, g: 0, b: 100 };
const COLOR_LIGHT_WALL: Color = Color {
  r: 130,
  g: 110,
  b: 50,
};
const COLOR_DARK_GROUND: Color = Color {
  r: 50,
  g: 50,
  b: 150,
};
const COLOR_LIGHT_GROUND: Color = Color {
  r: 200,
  g: 180,
  b: 50,
};
const ROOM_MAX_SIZE: i32 = 10;
const ROOM_MIN_SIZE: i32 = 6;
const MAX_ROOMS: i32 = 30;
const FOV_ALGO: FovAlgorithm = FovAlgorithm::Basic;
const FOV_LIGHT_WALLS: bool = true;
const TORCH_RADIUS: i32 = 10;
const MAX_ROOM_MONSTERS: i32 = 3;
const PLAYER: usize = 0;
// Sizes and coordinates relevant for the GUI
const BAR_WIDTH: i32 = 20;
const PANEL_HEIGHT: i32 = 7;
const PANEL_Y: i32 = SCREEN_HEIGHT - PANEL_HEIGHT;
const MSG_X: i32 = BAR_WIDTH + 2;
const MSG_WIDTH: i32 = SCREEN_WIDTH - BAR_WIDTH - 2;
const MSG_HEIGHT: usize = PANEL_HEIGHT as usize - 1;
const MAX_ROOM_ITEMS: i32 = 2;
const INVENTORY_WIDTH: i32 = 50;
const HEAL_AMOUNT: i32 = 4;
const LIGHTNING_DAMAGE: i32 = 40;
const LIGHTNING_RANGE: i32 = 5;
const CONFUSE_RANGE: i32 = 8;
const CONFUSE_NUM_TURNS: i32 = 10;
const FIREBALL_RADIUS: i32 = 3;
const FIREBALL_DAMAGE: i32 = 12;

struct Tcod {
  root: Root,
  con: Offscreen,
  panel: Offscreen,
  fov: FovMap,
  key: Key,
  mouse: Mouse,
}

#[derive(Debug)]
struct Object {
  x: i32,
  y: i32,
  char: char,
  color: Color,
  name: String,
  blocks: bool,
  alive: bool,
  fighter: Option<Fighter>,
  ai: Option<Ai>,
  item: Option<Item>,
}

impl Object {
  pub fn new(x: i32, y: i32, char: char, name: &str, color: Color, blocks: bool) -> Self {
    Object {
      x: x,
      y: y,
      char: char,
      color: color,
      name: name.into(),
      blocks: blocks,
      alive: false,
      fighter: None,
      ai: None,
      item: None,
    }
  }

  // Set the color and then draw the character that represents this object at its position
  pub fn draw(&self, con: &mut dyn Console) {
    con.set_default_foreground(self.color);
    con.put_char(self.x, self.y, self.char, BackgroundFlag::None);
  }

  pub fn pos(&self) -> (i32, i32) {
    (self.x, self.y)
  }

  pub fn set_pos(&mut self, x: i32, y: i32) {
    self.x = x;
    self.y = y;
  }

  pub fn distance_to(&self, other: &Object) -> f32 {
    let dx = other.x - self.x;
    let dy = other.y - self.y;
    ((dx.pow(2) + dy.pow(2)) as f32).sqrt()
  }

  pub fn take_damage(&mut self, damage: i32, game: &mut Game) {
    // Apply damage if possible
    if let Some(fighter) = self.fighter.as_mut() {
      if damage > 0 {
        fighter.hp -= damage;
      }
    }

    // Check for death, call the death function
    if let Some(fighter) = self.fighter {
      if fighter.hp <= 0 {
        self.alive = false;
        fighter.on_death.callback(self, game);
      }
    }
  }

  pub fn attack(&mut self, target: &mut Object, game: &mut Game) {
    // A simple formula for attack damage
    let damage = self.fighter.map_or(0, |f| f.power) - target.fighter.map_or(0, |f| f.defense);
    if damage > 0 {
      // Make the target take some damage
      game.messages.add(
        format!(
          "{} attacks {} for {} hit points.",
          self.name, target.name, damage
        ),
        WHITE,
      );

      target.take_damage(damage, game);
    } else {
      game.messages.add(
        format!(
          "{} attacks {} but it has no effect!",
          self.name, target.name
        ),
        WHITE,
      );
    }
  }

  pub fn heal(&mut self, amount: i32) {
    if let Some(ref mut fighter) = self.fighter {
      fighter.hp += amount;
      if fighter.hp > fighter.max_hp {
        fighter.hp = fighter.max_hp;
      }
    }
  }

  // Return the distance to some coordinates
  pub fn distance(&self, x: i32, y: i32) -> f32 {
    (((x - self.x).pow(2) + (y - self.y).pow(2)) as f32).sqrt()
  }
}

#[derive(Clone, Copy, Debug)]
struct Tile {
  blocked: bool,
  explored: bool,
  block_sight: bool,
}

impl Tile {
  pub fn empty() -> Self {
    Tile {
      blocked: false,
      explored: false,
      block_sight: false,
    }
  }

  pub fn wall() -> Self {
    Tile {
      blocked: true,
      explored: false,
      block_sight: true,
    }
  }
}

type Map = Vec<Vec<Tile>>;

struct Game {
  map: Map,
  messages: Messages,
  inventory: Vec<Object>,
}

// A rectangle on the map, used to characterise a room.
#[derive(Clone, Copy, Debug)]
struct Rect {
  x1: i32,
  y1: i32,
  x2: i32,
  y2: i32,
}

impl Rect {
  pub fn new(x: i32, y: i32, w: i32, h: i32) -> Self {
    Rect {
      x1: x,
      y1: y,
      x2: x + w,
      y2: y + h,
    }
  }

  pub fn center(&self) -> (i32, i32) {
    let center_x = (self.x1 + self.x2) / 2;
    let center_y = (self.y1 + self.y2) / 2;
    (center_x, center_y)
  }

  pub fn intersects_with(&self, other: &Rect) -> bool {
    (self.x1 <= other.x2) && (self.x2 >= other.x1) && (self.y1 <= other.y2) && (self.y2 >= other.y1)
  }
}

// Combat related properties and methods (monster, player, NPC).
#[derive(Clone, Copy, Debug, PartialEq)]
struct Fighter {
  max_hp: i32,
  hp: i32,
  defense: i32,
  power: i32,
  on_death: DeathCallback,
}

struct Messages {
  messages: Vec<(String, Color)>,
}

impl Messages {
  pub fn new() -> Self {
    Self { messages: vec![] }
  }

  // Add the new message as a tuple, with the text and the color
  pub fn add<T: Into<String>>(&mut self, message: T, color: Color) {
    self.messages.push((message.into(), color));
  }

  // Create a `DoubleEndedIterator` over the messages
  pub fn iter(&self) -> impl DoubleEndedIterator<Item = &(String, Color)> {
    self.messages.iter()
  }
}

#[derive(Clone, Copy, Debug, PartialEq)]
enum PlayerAction {
  TookTurn,
  DidntTakeTurn,
  Exit,
}

#[derive(Clone, Debug, PartialEq)]
enum Ai {
  Basic,
  Confused {
    previous_ai: Box<Ai>,
    num_turns: i32,
  },
}

#[derive(Clone, Copy, Debug, PartialEq)]
enum DeathCallback {
  Player,
  Monster,
}

impl DeathCallback {
  fn callback(self, object: &mut Object, game: &mut Game) {
    use DeathCallback::*;
    let callback = match self {
      Player => player_death,
      Monster => monster_death,
    };
    callback(object, game);
  }
}

#[derive(Clone, Copy, Debug, PartialEq)]
enum Item {
  Heal,
  Lightning,
  Confuse,
  Fireball,
}

enum UseResult {
  UsedUp,
  Cancelled,
}

fn handle_keys(tcod: &mut Tcod, game: &mut Game, objects: &mut Vec<Object>) -> PlayerAction {
  use tcod::input::Key;
  use tcod::input::KeyCode::*;
  use PlayerAction::*;

  let player_alive = objects[PLAYER].alive;
  match (tcod.key, tcod.key.text(), player_alive) {
    (
      Key {
        code: Enter,
        alt: true,
        ..
      },
      _,
      _,
    ) => {
      // Alt+Enter: toggle fullscreen
      let fullscreen = tcod.root.is_fullscreen();
      tcod.root.set_fullscreen(!fullscreen);
      DidntTakeTurn
    }
    (Key { code: Escape, .. }, _, _) => Exit, // exit game

    (Key { code: Up, .. }, _, true) => {
      player_move_or_attack(0, -1, game, objects);
      TookTurn
    }
    (Key { code: Down, .. }, _, true) => {
      player_move_or_attack(0, 1, game, objects);
      TookTurn
    }
    (Key { code: Left, .. }, _, true) => {
      player_move_or_attack(-1, 0, game, objects);
      TookTurn
    }
    (Key { code: Right, .. }, _, true) => {
      player_move_or_attack(1, 0, game, objects);
      TookTurn
    }

    (Key { code: Text, .. }, "g", true) => {
      // Pick up an item
      let item_id = objects
        .iter()
        .position(|object| object.pos() == objects[PLAYER].pos() && object.item.is_some());
      if let Some(item_id) = item_id {
        pick_item_up(item_id, game, objects);
      }
      DidntTakeTurn
    }

    (Key { code: Text, .. }, "i", true) => {
      // Show the inventory
      let inventory_index = inventory_menu(
        &game.inventory,
        "Press the key next to an item to use it, or any other to cancel.\n",
        &mut tcod.root,
      );
      if let Some(inventory_index) = inventory_index {
        use_item(inventory_index, tcod, game, objects);
      }
      DidntTakeTurn
    }

    (Key { code: Text, .. }, "d", true) => {
      // Show the inventory; if an item is selected, drop it
      let inventory_index = inventory_menu(
        &game.inventory,
        "Press the key next to an item to drop it, or any other to cancel.\n",
        &mut tcod.root,
      );
      if let Some(inventory_index) = inventory_index {
        drop_item(inventory_index, game, objects);
      }
      DidntTakeTurn
    }

    _ => DidntTakeTurn,
  }
}

fn make_map(objects: &mut Vec<Object>) -> Map {
  // Fill the map with unblocked tiles
  let mut map = vec![vec![Tile::wall(); MAP_HEIGHT as usize]; MAP_WIDTH as usize];

  let mut rooms = vec![];

  for _ in 0..MAX_ROOMS {
    let w = rand::thread_rng().gen_range(ROOM_MIN_SIZE, ROOM_MAX_SIZE + 1);
    let h = rand::thread_rng().gen_range(ROOM_MIN_SIZE, ROOM_MAX_SIZE + 1);
    let x = rand::thread_rng().gen_range(0, MAP_WIDTH - w);
    let y = rand::thread_rng().gen_range(0, MAP_HEIGHT - h);

    let new_room = Rect::new(x, y, w, h);
    let failed = rooms
      .iter()
      .any(|other_room| new_room.intersects_with(other_room));

    if !failed {
      create_room(new_room, &mut map);
      place_objects(new_room, &map, objects);
      let (new_x, new_y) = new_room.center();

      if rooms.is_empty() {
        objects[PLAYER].set_pos(new_x, new_y);
      } else {
        let (prev_x, prev_y) = rooms[rooms.len() - 1].center();

        if rand::random() {
          create_h_tunnel(prev_x, new_x, prev_y, &mut map);
          create_v_tunnel(prev_y, new_y, new_x, &mut map);
        } else {
          create_v_tunnel(prev_y, new_y, prev_x, &mut map);
          create_h_tunnel(prev_x, new_x, new_y, &mut map);
        }
      }
      rooms.push(new_room);
    }
  }

  map
}

fn create_room(room: Rect, map: &mut Map) {
  // Go through the tiles in the rectangle and make them passable
  for x in (room.x1 + 1)..room.x2 {
    for y in (room.y1 + 1)..room.y2 {
      map[x as usize][y as usize] = Tile::empty();
    }
  }
}

fn create_h_tunnel(x1: i32, x2: i32, y: i32, map: &mut Map) {
  // Horizontal tunnel. `min()` and `max()` are used in case
  // `x1 > x2`
  for x in cmp::min(x1, x2)..(cmp::max(x1, x2) + 1) {
    map[x as usize][y as usize] = Tile::empty();
  }
}

fn create_v_tunnel(y1: i32, y2: i32, x: i32, map: &mut Map) {
  // Vertical tunnel
  for y in cmp::min(y1, y2)..(cmp::max(y1, y2) + 1) {
    map[x as usize][y as usize] = Tile::empty();
  }
}

fn place_objects(room: Rect, map: &Map, objects: &mut Vec<Object>) {
  // Generate some monsters
  let num_monsters = rand::thread_rng().gen_range(0, MAX_ROOM_MONSTERS + 1);

  for _ in 0..num_monsters {
    let x = rand::thread_rng().gen_range(room.x1 + 1, room.x2);
    let y = rand::thread_rng().gen_range(room.y1 + 1, room.y2);

    if !is_blocked(x, y, map, objects) {
      let mut monster = if rand::random::<f32>() < 0.8 {
        // 80% chance of spawning an orc
        let mut orc = Object::new(x, y, 'o', "orc", DESATURATED_GREEN, true);
        orc.fighter = Some(Fighter {
          max_hp: 10,
          hp: 10,
          defense: 0,
          power: 3,
          on_death: DeathCallback::Monster,
        });
        orc.ai = Some(Ai::Basic);
        orc
      } else {
        // 20% chance of spawning a troll
        let mut troll = Object::new(x, y, 'T', "troll", DARKER_GREEN, true);
        troll.fighter = Some(Fighter {
          max_hp: 16,
          hp: 16,
          defense: 1,
          power: 4,
          on_death: DeathCallback::Monster,
        });
        troll.ai = Some(Ai::Basic);
        troll
      };

      monster.alive = true;
      objects.push(monster);
    }
  }

  // Generate some items
  let num_items = rand::thread_rng().gen_range(0, MAX_ROOM_ITEMS + 1);

  for _ in 0..num_items {
    // Choose random spot for this item
    let x = rand::thread_rng().gen_range(room.x1 + 1, room.x2);
    let y = rand::thread_rng().gen_range(room.y1 + 1, room.y2);

    // Only place it if the tile is note blocked
    if !is_blocked(x, y, map, objects) {
      let dice = rand::random::<f32>();
      let item = if dice < 0.7 {
        // Create a healing potion (70% chance)
        let mut object = Object::new(x, y, '!', "healing potion", VIOLET, false);
        object.item = Some(Item::Heal);
        object
      } else if dice < 0.7 + 0.1 {
        // Create a lightning bolt scroll (10% chance)
        let mut object = Object::new(x, y, '#', "scroll of lightning bolt", LIGHT_YELLOW, false);
        object.item = Some(Item::Lightning);
        object
      } else if dice < 0.7 + 0.1 + 0.1 {
        // Create a fireball scroll (10% chance)
        let mut object = Object::new(x, y, '#', "scroll of fireball", LIGHT_YELLOW, false);
        object.item = Some(Item::Fireball);
        object
      } else {
        // Create a confuse scroll (10% chance)
        let mut object = Object::new(x, y, '#', "scroll of confusion", LIGHT_YELLOW, false);
        object.item = Some(Item::Confuse);
        object
      };

      objects.push(item);
    }
  }
}

fn is_blocked(x: i32, y: i32, map: &Map, objects: &[Object]) -> bool {
  if map[x as usize][y as usize].blocked {
    return true;
  }

  objects
    .iter()
    .any(|object| object.blocks && object.pos() == (x, y))
}

// Move by given amount, if the destination is not blocked
fn move_by(id: usize, dx: i32, dy: i32, map: &Map, objects: &mut [Object]) {
  let (x, y) = objects[id].pos();
  if !is_blocked(x + dx, y + dy, map, objects) {
    objects[id].set_pos(x + dx, y + dy);
  }
}

fn player_move_or_attack(dx: i32, dy: i32, game: &mut Game, objects: &mut [Object]) {
  // The coordinates the player is moving to / attacking
  let x = objects[PLAYER].x + dx;
  let y = objects[PLAYER].y + dy;

  // Try to find an attackable object there
  let target_id = objects
    .iter()
    .position(|object| object.fighter.is_some() && object.pos() == (x, y));

  // Attack target if found, move otherwise
  match target_id {
    Some(target_id) => {
      let (player, target) = mut_two(PLAYER, target_id, objects);
      player.attack(target, game);
    }
    None => {
      move_by(PLAYER, dx, dy, &game.map, objects);
    }
  }
}

fn move_towards(id: usize, target_x: i32, target_y: i32, map: &Map, objects: &mut [Object]) {
  // Vector from this object to the target, and distance
  let dx = target_x - objects[id].x;
  let dy = target_y - objects[id].y;
  let distance = ((dx.pow(2) + dy.pow(2)) as f32).sqrt();

  // Normalize it to length 1 (preserving direction), then round it and
  // convert it to integer so the movement is restricted to the map grid
  let dx = (dx as f32 / distance).round() as i32;
  let dy = (dy as f32 / distance).round() as i32;
  move_by(id, dx, dy, map, objects);
}

fn ai_take_turn(monster_id: usize, tcod: &Tcod, game: &mut Game, objects: &mut [Object]) {
  use Ai::*;

  if let Some(ai) = objects[monster_id].ai.take() {
    let new_ai = match ai {
      Basic => ai_basic(monster_id, tcod, game, objects),
      Confused {
        previous_ai,
        num_turns,
      } => ai_confused(monster_id, tcod, game, objects, previous_ai, num_turns),
    };
    objects[monster_id].ai = Some(new_ai);
  }
}

fn ai_basic(monster_id: usize, tcod: &Tcod, game: &mut Game, objects: &mut [Object]) -> Ai {
  // A basic monster takes its turn. If you can see it, it can see you.
  let (monster_x, monster_y) = objects[monster_id].pos();
  if tcod.fov.is_in_fov(monster_x, monster_y) {
    if objects[monster_id].distance_to(&objects[PLAYER]) >= 2.0 {
      // Move towards player if far away
      let (player_x, player_y) = objects[PLAYER].pos();
      move_towards(monster_id, player_x, player_y, &game.map, objects);
    } else if objects[PLAYER].fighter.map_or(false, |f| f.hp > 0) {
      // Close enough, attach! (if the player is still alive.)
      let (monster, player) = mut_two(monster_id, PLAYER, objects);
      monster.attack(player, game);
    }
  }
  Ai::Basic
}

fn ai_confused(
  monster_id: usize,
  _tcod: &Tcod,
  game: &mut Game,
  objects: &mut [Object],
  previous_ai: Box<Ai>,
  num_turns: i32,
) -> Ai {
  if num_turns >= 0 {
    // Still confused ...
    // Move in a random direction, and decrease the number of turns confused
    move_by(
      monster_id,
      rand::thread_rng().gen_range(-1, 2),
      rand::thread_rng().gen_range(-1, 2),
      &game.map,
      objects,
    );

    Ai::Confused {
      previous_ai: previous_ai,
      num_turns: num_turns - 1,
    }
  } else {
    // Restore previous AI (this one will be deleted)
    game.messages.add(
      format!("The {} is no longer confused!", objects[monster_id].name),
      RED,
    );
    *previous_ai
  }
}

fn mut_two<T>(first_index: usize, second_index: usize, items: &mut [T]) -> (&mut T, &mut T) {
  assert!(first_index != second_index);
  let split_at_index = cmp::max(first_index, second_index);
  let (first_slice, second_slice) = items.split_at_mut(split_at_index);
  if first_index < second_index {
    (&mut first_slice[first_index], &mut second_slice[0])
  } else {
    (&mut second_slice[0], &mut first_slice[second_index])
  }
}

fn player_death(player: &mut Object, game: &mut Game) {
  // The game ended!
  game.messages.add("You died!", RED);

  // For added effect, transform the player into corpse!
  player.char = '%';
  player.color = DARK_RED;
}

fn monster_death(monster: &mut Object, game: &mut Game) {
  // Transform it into a nasty corpse! It doesn't block, can't be
  // attacked and doesn't move
  game
    .messages
    .add(format!("{} is dead!", monster.name), ORANGE);
  monster.char = '%';
  monster.color = DARK_RED;
  monster.blocks = false;
  monster.fighter = None;
  monster.ai = None;
  monster.name = format!("remains of {}", monster.name);
}

fn menu<T: AsRef<str>>(header: &str, options: &[T], width: i32, root: &mut Root) -> Option<usize> {
  // Limit the amount of menu options
  assert!(
    options.len() <= 26,
    "Cannot have a menu with more than 26 options."
  );

  // Calculate total height for the header (after auto-wrap) and one line per option
  let header_height = if header.is_empty() {
    0
  } else {
    root.get_height_rect(0, 0, width, SCREEN_HEIGHT, header)
  };
  let height = options.len() as i32 + header_height;

  // Create an off-screen console that represents the menu's window
  let mut window = Offscreen::new(width, height);

  // Print the header, with auto-wrap
  window.set_default_foreground(WHITE);
  window.print_rect_ex(
    0,
    0,
    width,
    height,
    BackgroundFlag::None,
    TextAlignment::Left,
    header,
  );

  // Print all the options
  for (index, option_text) in options.iter().enumerate() {
    let menu_letter = (b'a' + index as u8) as char;
    let text = format!("({}) {}", menu_letter, option_text.as_ref());
    window.print_ex(
      0,
      header_height + index as i32,
      BackgroundFlag::None,
      TextAlignment::Left,
      text,
    );
  }

  // Blit the contents of the menu window to the root console
  let x = SCREEN_WIDTH / 2 - width / 2;
  let y = SCREEN_HEIGHT / 2 - height / 2;
  blit(&window, (0, 0), (width, height), root, (x, y), 1.0, 0.7);

  // Present the root console to the player and wait for a key-press
  root.flush();
  let key = root.wait_for_keypress(true);

  // Convert the ASCII code to an index; if it corresponds to an option, return it
  if key.printable.is_alphabetic() {
    let index = key.printable.to_ascii_lowercase() as usize - 'a' as usize;
    if index < options.len() {
      Some(index)
    } else {
      None
    }
  } else {
    None
  }
}

fn inventory_menu(inventory: &[Object], header: &str, root: &mut Root) -> Option<usize> {
  // Show a menu with each inventory item as an option
  let options = if inventory.len() == 0 {
    vec!["Inventory is empty.".into()]
  } else {
    inventory.iter().map(|item| item.name.clone()).collect()
  };

  let inventory_index = menu(header, &options, INVENTORY_WIDTH, root);

  // If an item was chosen, return it
  if inventory.len() > 0 {
    inventory_index
  } else {
    None
  }
}

fn render_bar(
  panel: &mut Offscreen,
  x: i32,
  y: i32,
  total_width: i32,
  name: &str,
  value: i32,
  maximum: i32,
  bar_color: Color,
  back_color: Color,
) {
  // Render a bar (HP, experience, etc). First calculate the width of the bar
  let bar_width = (value as f32 / maximum as f32 * total_width as f32) as i32;

  // Render the background first
  panel.set_default_background(back_color);
  panel.rect(x, y, total_width, 1, false, BackgroundFlag::Screen);

  // Now render the bar on top
  panel.set_default_background(bar_color);
  if bar_width > 0 {
    panel.rect(x, y, bar_width, 1, false, BackgroundFlag::Screen);
  }

  // Finally, some centered text with the values
  panel.set_default_foreground(WHITE);
  panel.print_ex(
    x + total_width / 2,
    y,
    BackgroundFlag::None,
    TextAlignment::Center,
    &format!("{}: {}/{}", name, value, maximum),
  );
}

fn get_names_under_mouse(mouse: Mouse, objects: &[Object], fov_map: &FovMap) -> String {
  let (x, y) = (mouse.cx as i32, mouse.cy as i32);

  // Create a list with the names of all objects at the mouse's coordinates and in FOV
  let names = objects
    .iter()
    .filter(|obj| obj.pos() == (x, y) && fov_map.is_in_fov(obj.x, obj.y))
    .map(|obj| obj.name.clone())
    .collect::<Vec<_>>();

  names.join(", ")
}

fn pick_item_up(object_id: usize, game: &mut Game, objects: &mut Vec<Object>) {
  if game.inventory.len() >= 26 {
    game.messages.add(
      format!(
        "Your inventory is full, cannot pick up {}.",
        objects[object_id].name
      ),
      RED,
    );
  } else {
    let item = objects.swap_remove(object_id);
    game
      .messages
      .add(format!("You picked up a {}!", item.name), GREEN);
    game.inventory.push(item);
  }
}

fn use_item(inventory_id: usize, tcod: &mut Tcod, game: &mut Game, objects: &mut [Object]) {
  use Item::*;
  // just call the "use_function" if it is defined
  if let Some(item) = game.inventory[inventory_id].item {
    let on_use = match item {
      Heal => cast_heal,
      Lightning => cast_lightning,
      Confuse => cast_confuse,
      Fireball => cast_fireball,
    };
    match on_use(inventory_id, tcod, game, objects) {
      UseResult::UsedUp => {
        // Destroy after use, unless it was cancelled for some reason
        game.inventory.remove(inventory_id);
      }
      UseResult::Cancelled => {
        game.messages.add("Cancelled", WHITE);
      }
    }
  } else {
    game.messages.add(
      format!("The {} cannot be used.", game.inventory[inventory_id].name),
      WHITE,
    );
  }
}

fn cast_heal(
  _inventory_id: usize,
  _tcod: &mut Tcod,
  game: &mut Game,
  objects: &mut [Object],
) -> UseResult {
  // Heal the player
  if let Some(fighter) = objects[PLAYER].fighter {
    if fighter.hp == fighter.max_hp {
      game.messages.add("You are already at full health.", RED);
      return UseResult::Cancelled;
    }

    game
      .messages
      .add("Your wounds start to feel better!", LIGHT_VIOLET);
    objects[PLAYER].heal(HEAL_AMOUNT);
    return UseResult::UsedUp;
  }
  UseResult::Cancelled
}

fn cast_lightning(
  _inventory_id: usize,
  tcod: &mut Tcod,
  game: &mut Game,
  objects: &mut [Object],
) -> UseResult {
  // Find closest enemy (inside a maximum range) and damage it
  let monster_id = closest_monster(tcod, objects, LIGHTNING_RANGE);
  if let Some(monster_id) = monster_id {
    // Zap it !
    game.messages.add(
      format!(
        "A lightning bolt strikes the {} with a loud thunder! \
          The damage is {} hit points.",
        objects[monster_id].name, LIGHTNING_DAMAGE
      ),
      LIGHT_BLUE,
    );
    objects[monster_id].take_damage(LIGHTNING_DAMAGE, game);
    UseResult::UsedUp
  } else {
    // No enemy found within maximum range
    game
      .messages
      .add("No enemy is close enough to strike.", RED);

    UseResult::Cancelled
  }
}

fn cast_confuse(
  _inventory_id: usize,
  tcod: &mut Tcod,
  game: &mut Game,
  objects: &mut [Object],
) -> UseResult {
  game.messages.add(
    "Left-click an enemy to confuse it, or right click to cancel.",
    LIGHT_CYAN,
  );
  let monster_id = target_monster(tcod, game, objects, Some(CONFUSE_RANGE as f32));
  if let Some(monster_id) = monster_id {
    let old_ai = objects[monster_id].ai.take().unwrap_or(Ai::Basic);
    // Replace the monster's AI with a "confused" one; after
    // some turns it will restore the old AI
    objects[monster_id].ai = Some(Ai::Confused {
      previous_ai: Box::new(old_ai),
      num_turns: CONFUSE_NUM_TURNS,
    });
    game.messages.add(
      format!(
        "The eyes of {} look vacant, as he starts to stumble around!",
        objects[monster_id].name
      ),
      LIGHT_GREEN,
    );
    UseResult::UsedUp
  } else {
    // No enemy found within maximum range
    game
      .messages
      .add("No enemy is close enough to strike.", RED);
    UseResult::Cancelled
  }
}

fn cast_fireball(
  _inventory_id: usize,
  tcod: &mut Tcod,
  game: &mut Game,
  objects: &mut [Object],
) -> UseResult {
  // Ask the player for a target tile to throw a fireball at
  game.messages.add(
    "Left-click a target tile for the fireball, or right-click to cancel.",
    LIGHT_CYAN,
  );
  let (x, y) = match target_tile(tcod, game, objects, None) {
    Some(tile_pos) => tile_pos,
    None => return UseResult::Cancelled,
  };
  game.messages.add(
    format!(
      "The fireball explodes, burning everything within {} tiles!",
      FIREBALL_RADIUS
    ),
    ORANGE,
  );

  for obj in objects {
    if obj.distance(x, y) <= FIREBALL_RADIUS as f32 && obj.fighter.is_some() {
      game.messages.add(
        format!(
          "The {} gets burned for {} hit points.",
          obj.name, FIREBALL_DAMAGE
        ),
        ORANGE,
      );
      obj.take_damage(FIREBALL_DAMAGE, game);
    }
  }
  UseResult::UsedUp
}

// Find closest enemy, up to a maximum range, and in the player's FOV
fn closest_monster(tcod: &Tcod, objects: &[Object], max_range: i32) -> Option<usize> {
  let mut closest_enemy = None;
  // Start with (slightly more) than maximum range
  let mut closest_dist = (max_range + 1) as f32;

  for (id, object) in objects.iter().enumerate() {
    if (id != PLAYER)
      && object.fighter.is_some()
      && object.ai.is_some()
      && tcod.fov.is_in_fov(object.x, object.y)
    {
      // Calculate the distance between this object and the player
      let dist = objects[PLAYER].distance_to(object);
      if dist < closest_dist {
        // It's closer, so remember it
        closest_enemy = Some(id);
        closest_dist = dist;
      }
    }
  }
  closest_enemy
}

// Return the position of a tile left-clicked in player's FOV (optionally in a
// range), or (None, None) if right-clicked.
fn target_tile(
  tcod: &mut Tcod,
  game: &mut Game,
  objects: &[Object],
  max_range: Option<f32>,
) -> Option<(i32, i32)> {
  use tcod::input::KeyCode::Escape;

  loop {
    // Render the screen. This erases the inventory and shows the names of
    // objects under the mouse.
    tcod.root.flush();
    let event = input::check_for_event(input::KEY_PRESS | input::MOUSE).map(|e| e.1);
    match event {
      Some(Event::Mouse(m)) => tcod.mouse = m,
      Some(Event::Key(k)) => tcod.key = k,
      None => tcod.key = Default::default(),
    }
    render_all(tcod, game, objects, false);

    let (x, y) = (tcod.mouse.cx as i32, tcod.mouse.cy as i32);

    // Accept the target if the player clicked in FOV, and in case a range
    // is specified, if it's in that range
    let in_fov = (x < MAP_WIDTH) && (y < MAP_HEIGHT) && tcod.fov.is_in_fov(x, y);
    let in_range = max_range.map_or(true, |range| objects[PLAYER].distance(x, y) <= range);
    if tcod.mouse.lbutton_pressed && in_fov && in_range {
      return Some((x, y));
    }

    if tcod.mouse.rbutton_pressed || tcod.key.code == Escape {
      return None; // Cancel if the player right-clicked or pressed escape.
    }
  }
}

// Returns a clicked monster inside FOV up to a range, or None if right-clicked
fn target_monster(
  tcod: &mut Tcod,
  game: &mut Game,
  objects: &[Object],
  max_range: Option<f32>,
) -> Option<usize> {
  loop {
    match target_tile(tcod, game, objects, max_range) {
      Some((x, y)) => {
        // Return the first clicked monster, otherwise continue looping
        for (id, obj) in objects.iter().enumerate() {
          if obj.pos() == (x, y) && obj.fighter.is_some() && id != PLAYER {
            return Some(id);
          }
        }
      }
      None => return None,
    }
  }
}

fn drop_item(inventory_id: usize, game: &mut Game, objects: &mut Vec<Object>) {
  let mut item = game.inventory.remove(inventory_id);
  item.set_pos(objects[PLAYER].x, objects[PLAYER].y);
  game
    .messages
    .add(format!("You dropped a {}.", item.name), YELLOW);
  objects.push(item);
}

fn render_all(tcod: &mut Tcod, game: &mut Game, objects: &[Object], fov_recompute: bool) {
  if fov_recompute {
    let player = &objects[PLAYER];
    tcod
      .fov
      .compute_fov(player.x, player.y, TORCH_RADIUS, FOV_LIGHT_WALLS, FOV_ALGO);
  }

  // Only render objects in fov
  let mut to_draw: Vec<_> = objects
    .iter()
    .filter(|o| tcod.fov.is_in_fov(o.x, o.y))
    .collect();

  // Sort so that non-blocking objects are rendered behind blocking objects
  to_draw.sort_by(|o1, o2| o1.blocks.cmp(&o2.blocks));

  // Draw objects in the list
  for object in &to_draw {
    object.draw(&mut tcod.con);
  }

  // Go through all tiles and set their background color
  for y in 0..MAP_HEIGHT {
    for x in 0..MAP_WIDTH {
      let visible = tcod.fov.is_in_fov(x, y);
      let wall = game.map[x as usize][y as usize].block_sight;
      let color = match (visible, wall) {
        // Outside fov:
        (false, true) => COLOR_DARK_WALL,
        (false, false) => COLOR_DARK_GROUND,
        // INside fov:
        (true, true) => COLOR_LIGHT_WALL,
        (true, false) => COLOR_LIGHT_GROUND,
      };
      let explored = &mut game.map[x as usize][y as usize].explored;
      if visible {
        *explored = true;
      }
      if *explored {
        tcod
          .con
          .set_char_background(x, y, color, BackgroundFlag::Set);
      }
    }
  }

  // Blit contents of "con" to the root console
  blit(
    &tcod.con,
    (0, 0),
    (MAP_WIDTH, MAP_HEIGHT),
    &mut tcod.root,
    (0, 0),
    1.0,
    1.0,
  );

  // Prepare to render the GUI panel
  tcod.panel.set_default_background(BLACK);
  tcod.panel.clear();

  // Show the player's stats
  let hp = objects[PLAYER].fighter.map_or(0, |f| f.hp);
  let max_hp = objects[PLAYER].fighter.map_or(0, |f| f.max_hp);
  render_bar(
    &mut tcod.panel,
    1,
    1,
    BAR_WIDTH,
    "HP",
    hp,
    max_hp,
    LIGHT_RED,
    DARKER_RED,
  );

  // Display names of objects under the mouse
  tcod.panel.set_default_foreground(LIGHT_GREY);
  tcod.panel.print_ex(
    1,
    0,
    BackgroundFlag::None,
    TextAlignment::Left,
    get_names_under_mouse(tcod.mouse, objects, &tcod.fov),
  );

  // Print the game messages, one line at a time
  let mut y = MSG_HEIGHT as i32;
  for &(ref msg, color) in game.messages.iter().rev() {
    let msg_height = tcod.panel.get_height_rect(MSG_X, y, MSG_WIDTH, 0, msg);
    y -= msg_height;
    if y < 0 {
      break;
    }
    tcod.panel.set_default_foreground(color);
    tcod.panel.print_rect(MSG_X, y, MSG_WIDTH, 0, msg);
  }

  // Blit contents of "panel" to the root console
  blit(
    &tcod.panel,
    (0, 0),
    (SCREEN_WIDTH, PANEL_HEIGHT),
    &mut tcod.root,
    (0, PANEL_Y),
    1.0,
    1.0,
  );
}

fn initialise_fov(tcod: &mut Tcod, map: &Map) {
  // Populate FOV map, according to generated map
  for y in 0..MAP_HEIGHT {
    for x in 0..MAP_WIDTH {
      tcod.fov.set(
        x,
        y,
        !map[x as usize][y as usize].block_sight,
        !map[x as usize][y as usize].blocked,
      )
    }
  }
}

fn new_game(tcod: &mut Tcod) -> (Game, Vec<Object>) {
  // Create player object
  let mut player = Object::new(0, 0, '@', "player", WHITE, true);
  player.alive = true;
  player.fighter = Some(Fighter {
    max_hp: 30,
    hp: 30,
    defense: 2,
    power: 5,
    on_death: DeathCallback::Player,
  });

  // List of objects in the world
  let mut objects = vec![player];

  let mut game = Game {
    // Generate map
    map: make_map(&mut objects),
    messages: Messages::new(),
    inventory: vec![],
  };

  initialise_fov(tcod, &game.map);

  // A warm welcoming message!
  game.messages.add(
    "Welcome stranger! Prepare to perish in the Tomb of Doom.",
    RED,
  );

  (game, objects)
}

fn play_game(tcod: &mut Tcod, game: &mut Game, objects: &mut Vec<Object>) {
  // force FOV "recompute" first time through the game loop
  let mut previous_player_position = (-1, -1);

  // Main game loop
  while !tcod.root.window_closed() {
    // clear the screen of the previous frame
    tcod.con.clear();

    match input::check_for_event(input::MOUSE | input::KEY_PRESS) {
      Some((_, Event::Mouse(m))) => tcod.mouse = m,
      Some((_, Event::Key(k))) => tcod.key = k,
      _ => tcod.key = Default::default(),
    }

    // Render the screen
    let fov_recompute = previous_player_position != (objects[PLAYER].pos());
    render_all(tcod, game, &objects, fov_recompute);

    tcod.root.flush();

    // Handle keys and exit game if needed
    previous_player_position = objects[PLAYER].pos();
    let player_action = handle_keys(tcod, game, objects);
    if player_action == PlayerAction::Exit {
      break;
    }

    // Let monsters take their turn
    if objects[PLAYER].alive && player_action != PlayerAction::DidntTakeTurn {
      for id in 0..objects.len() {
        if objects[id].ai.is_some() {
          ai_take_turn(id, tcod, game, objects);
        }
      }
    }
  }
}

fn main_menu(tcod: &mut Tcod) {
  let img = tcod::image::Image::from_file("menu_background.png")
    .ok()
    .expect("Background image not found");

  while !tcod.root.window_closed() {
    // Show the background image, at twice the regular console resolution
    tcod::image::blit_2x(&img, (0, 0), (-1, -1), &mut tcod.root, (0, 0));

    tcod.root.set_default_foreground(LIGHT_YELLOW);
    tcod.root.print_ex(
      SCREEN_WIDTH / 2,
      SCREEN_HEIGHT / 2 - 4,
      BackgroundFlag::None,
      TextAlignment::Center,
      "TOMB OF DOOM",
    );
    tcod.root.print_ex(
      SCREEN_WIDTH / 2,
      SCREEN_HEIGHT - 2,
      BackgroundFlag::None,
      TextAlignment::Center,
      "By m",
    );

    // Show options and wait for the player's choice
    let choices = &["Play a new game", "Continue last game", "Quit"];
    let choice = menu("", choices, 24, &mut tcod.root);

    match choice {
      Some(0) => {
        // New game
        let (mut game, mut objects) = new_game(tcod);
        play_game(tcod, &mut game, &mut objects);
      }
      Some(2) => {
        // Quit
        break;
      }
      _ => {}
    }
  }
}

fn main() {
  tcod::system::set_fps(FPS);

  let root = Root::initializer()
    .font("arial10x10.png", FontLayout::Tcod)
    .font_type(FontType::Greyscale)
    .size(SCREEN_WIDTH, SCREEN_HEIGHT)
    .title("Rust/libtcod tutorial")
    .init();

  let mut tcod = Tcod {
    root,
    con: Offscreen::new(MAP_WIDTH, MAP_HEIGHT),
    panel: Offscreen::new(SCREEN_WIDTH, PANEL_HEIGHT),
    fov: FovMap::new(MAP_WIDTH, MAP_HEIGHT),
    key: Default::default(),
    mouse: Default::default(),
  };

  main_menu(&mut tcod);
}