use std::cmp::{max, min};

use rand::rngs::ThreadRng;
use rand::Rng;

use crate::artifacts::Artifact;
#[cfg(test)]
use crate::artifacts::{Chest, Potion};
use crate::monster::Monster;
#[cfg(test)]
use crate::monster::{Orc, Rat};
use crate::player::Player;
use crate::position::HasPosition;
use crate::position::Position;

pub const LEVEL_WIDTH: usize = 50;
pub const LEVEL_HEIGHT: usize = 25;

#[derive(Copy, Clone, Debug, PartialEq)]
pub enum StructureElement {
    Start,
    End,
    Wall,
    Floor,
    StairDown,
    StairUp,
    Unknown,
}

type PossibleArtifact<'a> = Option<&'a mut Box<(dyn Artifact + 'static)>>;
type PossibleMonster<'a> = Option<&'a mut Box<(dyn Monster + 'static)>>;

pub struct Level {
    pub(crate) level: usize,
    pub(crate) structure: [[StructureElement; LEVEL_HEIGHT]; LEVEL_WIDTH],
    pub(crate) discovered: [[bool; LEVEL_HEIGHT]; LEVEL_WIDTH],
    pub(crate) monsters: Vec<Box<dyn Monster>>,
    pub(crate) artifacts: Vec<Box<dyn Artifact>>,
    /// the position of the start in the level (either stair up or start point)
    pub(crate) start: (usize, usize),
    /// the position of the end in the level (either stair down or end point)
    pub(crate) end: (usize, usize),
    pub(crate) rng: ThreadRng,
}

impl Level {
    pub fn get_element(
        &mut self,
        x: i16,
        y: i16,
    ) -> (
        Option<StructureElement>,
        PossibleMonster,
        PossibleArtifact
    ) {
        if x < 0 || y < 0 {
            return (None, None, None);
        }
        let x = x as usize;
        let y = y as usize;
        if x >= LEVEL_WIDTH || y >= LEVEL_HEIGHT {
            return (None, None, None);
        }
        if !self.discovered[x][y] {
            return (Some(StructureElement::Unknown), None, None);
        }
        let search_pos = &Position::new(self.level, x, y);
        let mut res_m: Option<&mut Box<dyn Monster>> = None;
        for m in &mut self.monsters {
            if m.get_immutable_position() == search_pos {
                res_m = Some(m);
            }
        }
        let mut res_a: Option<&mut Box<dyn Artifact>> = None;
        for a in &mut self.artifacts {
            if a.get_immutable_position() == search_pos {
                res_a = Some(a);
            }
        }
        (Some(self.structure[x][y]), res_m, res_a)
    }
    /// discover the area with in the level around the given position
    pub fn discover(&mut self, pos: &Position) {
        let x = pos.get_x();
        let y = pos.get_y();

        // uncover fields directly next to the player
        for x_r in max(x - 1, 0)..=min(x + 1, LEVEL_WIDTH - 1) {
            for y_r in max(y - 1, 0)..=min(y + 1, LEVEL_HEIGHT - 1) {
                self.discovered[x_r][y_r] = true;
            }
        }

        // uncover fields up to 2 fields right of the player
        for x_r in x..=min(x + 2, LEVEL_WIDTH - 1) {
            self.discovered[x_r][y] = true;
            if self.structure[x_r][y] == StructureElement::Wall {
                break;
            }
        }

        // uncover fields up to 2 fields below of the player
        for y_r in y..=min(y + 2, LEVEL_HEIGHT - 1) {
            self.discovered[x][y_r] = true;
            if self.structure[x][y_r] == StructureElement::Wall {
                break;
            }
        }

        // uncover fields up to 2 fields left of the player
        for x_r in (max(x, 2)..x + 2).rev() {
            self.discovered[x_r - 2][y] = true;
            if self.structure[x_r - 2][y] == StructureElement::Wall {
                break;
            }
        }

        // uncover fields up to 2 fields above of the player
        for y_r in (max(y, 2)..y + 2).rev() {
            self.discovered[x][y_r - 2] = true;
            if self.structure[x][y_r - 2] == StructureElement::Wall {
                break;
            }
        }
    }
    pub fn update(&mut self, ticks: u128, player: &mut Player, messages: &mut Vec<String>) {
        for (index, a) in &mut self.artifacts.iter().enumerate() {
            if a.was_collected() {
                self.artifacts.remove(index);
                break;
            }
        }
        for index in 0..self.monsters.len() {
            if self.monsters[index].is_dead() {
                continue;
            }
            if ticks % self.monsters[index].get_ticks_between_steps() != 0 {
                continue;
            }
            loop {
                // calculate the direction the monster will try to walk
                let (dx, dy) = match self.rng.gen_range(0..5) {
                    1 => (1, 0),
                    2 => (-1, 0),
                    3 => (0, 1),
                    4 => (0, -1),
                    _ => (0, 0),
                };
                if self.can_monster_move(self.monsters[index].as_ref(), dx, dy) {
                    let (new_x, new_y) = self.monsters[index].get_position().change(dx, dy);
                    if player.get_immutable_position().get_x() == new_x
                        && player.get_immutable_position().get_y() == new_y
                    {
                        self.monsters[index].decrease_life(1);
                        player.change_life(-1);
                        messages.insert(
                            0,
                            format!("{} hits you.", self.monsters[index].get_name()).to_string(),
                        );
                        messages.insert(
                            0,
                            format!("you hit {}.", self.monsters[index].get_name()).to_string(),
                        );
                        // if the attack did not kill the opponent, back down
                        if !player.is_dead() {
                            self.monsters[index].get_position().change(-dx, -dy);
                        }
                    }
                    break;
                }
            }
        }
        for (index, m) in &mut self.monsters.iter().enumerate() {
            if m.is_dead() {
                self.monsters.remove(index);
                break;
            }
        }
    }

    pub fn can_monster_move(&self, agent: &dyn Monster, dx: i16, dy: i16) -> bool {
        let agent_pos = agent.get_immutable_position();
        let new_x: usize = (agent_pos.get_x() as i16 + dx) as usize;
        let new_y: usize = (agent_pos.get_y() as i16 + dy) as usize;

        // verify we cannot leave the playing field
        if new_x >= LEVEL_WIDTH || new_y >= LEVEL_HEIGHT {
            return false;
        }

        for index in 0..self.monsters.len() {
            let pos = self.monsters[index].get_immutable_position();
            if pos.get_x() == new_x && pos.get_y() == new_y {
                return false;
            }
        }
        self.structure[new_x][new_y] != StructureElement::Wall
    }
    pub fn can_player_move(&self, agent: &Player, dx: i16, dy: i16) -> bool {
        let agent_pos = agent.get_immutable_position();
        let new_x: usize = (agent_pos.get_x() as i16 + dx) as usize;
        let new_y: usize = (agent_pos.get_y() as i16 + dy) as usize;

        // verify we cannot leave the playing field
        if new_x >= LEVEL_WIDTH || new_y >= LEVEL_HEIGHT {
            return false;
        }

        self.structure[new_x][new_y] != StructureElement::Wall
    }
    #[cfg(test)]
    pub fn new(level: usize) -> Level {
        let mut s = [[StructureElement::Wall; LEVEL_HEIGHT]; LEVEL_WIDTH];
        for x in 2..LEVEL_WIDTH - 2 {
            for y in 2..LEVEL_HEIGHT - 2 {
                s[x][y] = StructureElement::Floor;
            }
        }
        Level {
            level,
            structure: s,
            discovered: [[false; LEVEL_HEIGHT]; LEVEL_WIDTH],
            monsters: Vec::with_capacity(10),
            artifacts: Vec::with_capacity(10),
            start: (0, 0),
            end: (0, 0),
            rng: rand::thread_rng(),
        }
    }
    #[cfg(test)]
    pub fn add_monster(&mut self, mut monster: impl Monster + 'static) -> Result<(), String> {
        if self.level != monster.get_position().get_level() {
            return Err("Wrong Level".to_string());
        }
        for m in &mut self.monsters {
            if m.get_position() == monster.get_position() {
                return Err("Position already used".to_string());
            }
        }
        self.monsters.push(Box::new(monster));
        Ok(())
    }
    #[cfg(test)]
    pub fn add_artifact(&mut self, artifact: impl Artifact + 'static) -> Result<(), String> {
        if self.level != artifact.get_immutable_position().get_level() {
            return Err("Wrong Level".to_string());
        }
        for a in &mut self.artifacts {
            if a.get_immutable_position() == artifact.get_immutable_position() {
                return Err("Position already used".to_string());
            }
        }
        self.artifacts.push(Box::new(artifact));
        Ok(())
    }
}

#[test]
fn test_get_element() {
    let mut l = Level::new(0);
    assert_eq!(l.get_element(-1, -1).0, None);
    assert_eq!(l.get_element(0, 0).0.unwrap(), StructureElement::Unknown);
    assert_eq!(
        l.get_element(LEVEL_WIDTH as i16 - 1, LEVEL_HEIGHT as i16 - 1)
            .0
            .unwrap(),
        StructureElement::Unknown
    );
    assert_eq!(
        l.get_element(LEVEL_WIDTH as i16, LEVEL_HEIGHT as i16).0,
        None
    );
}

#[test]
fn test_discover_get_element() {
    let mut l = Level::new(0);
    assert_eq!(l.get_element(10, 10).0.unwrap(), StructureElement::Unknown);
    let p = Position::new(0, 10, 10);
    l.discover(&p);
    assert_eq!(l.get_element(10, 10).0.unwrap(), StructureElement::Floor);
    assert_eq!(l.get_element(9, 10).0.unwrap(), StructureElement::Floor);
    assert_eq!(l.get_element(10, 9).0.unwrap(), StructureElement::Floor);
    assert_eq!(l.get_element(11, 10).0.unwrap(), StructureElement::Floor);
    assert_eq!(l.get_element(10, 11).0.unwrap(), StructureElement::Floor);
}

#[test]
fn test_discover_can_add_monster() {
    let mut l = Level::new(0);
    let m = Rat::new_with_position(Position::new(1, 2, 3));
    assert_eq!(l.add_monster(m), Err("Wrong Level".to_string()));

    let mut m = Orc::new_with_position(Position::new(0, 2, 3));
    m.get_position().set(0, 2, 3);
    assert_eq!(l.add_monster(m), Ok(()));

    let m = Rat::new_with_position(Position::new(0, 2, 3));
    assert_eq!(l.add_monster(m), Err("Position already used".to_string()));

    let m = Rat::new_with_position(Position::new(0, 2, 4));
    assert_eq!(l.add_monster(m), Ok(()));
}

#[test]
fn test_discover_can_add_artifact() {
    let mut l = Level::new(0);
    let a = Chest::new(Position::new(1, 2, 3));
    assert_eq!(l.add_artifact(a), Err("Wrong Level".to_string()));

    let a = Chest::new(Position::new(0, 2, 3));
    assert_eq!(l.add_artifact(a), Ok(()));

    let a = Potion::new(Position::new(0, 2, 3));
    assert_eq!(l.add_artifact(a), Err("Position already used".to_string()));

    let a = Chest::new(Position::new(0, 1, 3));
    assert_eq!(l.add_artifact(a), Ok(()));
}

#[test]
fn test_discover_get_monster() {
    let mut l = Level::new(0);
    let p = Position::new(0, 10, 10);
    l.discover(&p);
    assert_eq!(l.get_element(10, 10).0.unwrap(), StructureElement::Floor);
    assert!(l.get_element(10, 10).1.is_none());

    let m = Rat::new_with_position(Position::new(0, 10, 10));
    assert_eq!(l.add_monster(m), Ok(()));

    let elem = l.get_element(10, 10);
    assert_eq!(elem.0.unwrap(), StructureElement::Floor);
    assert!(elem.1.is_some());
    let m = elem.1.unwrap();
    assert_eq!(m.get_life(), 2);

    m.decrease_life(2);
    assert_eq!(l.get_element(10, 10).1.unwrap().get_life(), 0);
}

#[test]
fn test_discover_get_artifact() {
    let mut l = Level::new(0);
    let p = Position::new(0, 10, 10);
    l.discover(&p);
    assert_eq!(l.get_element(10, 10).0.unwrap(), StructureElement::Floor);
    assert!(l.get_element(10, 10).2.is_none());

    let a = Chest::new(Position::new(0, 10, 10));
    assert_eq!(l.add_artifact(a), Ok(()));

    let elem = l.get_element(10, 10);
    assert_eq!(elem.0.unwrap(), StructureElement::Floor);
    assert!(elem.2.is_some());
}

#[test]
fn test_discover_get_monster_can_move() {
    let mut l = Level::new(0);
    let p = Position::new(0, 10, 10);
    l.discover(&p);

    let m = Rat::new_with_position(Position::new(0, 10, 10));
    l.add_monster(m).expect("Panic because of");

    let m = l.get_element(10, 10).1.unwrap();
    m.get_position().change(1, 1);

    let m = l.get_element(10, 10).1;
    assert!(m.is_none());
    let m = l.get_element(11, 11).1;
    assert!(m.is_some());
    assert_eq!(m.unwrap().get_life(), 2);
}