use crate::geometry::*;
use crate::command::Command;
use crate::json;

use arrayvec::ArrayVec;

#[derive(Debug, PartialEq, Eq)]
pub struct GameBoard {
    pub players: [Player; 2],
    pub powerups: ArrayVec<[Powerup; 2]>,
    pub map: Map,
}

#[derive(Debug, PartialEq, Eq)]
pub struct Player {
    pub active_worm: usize,
    pub worms: ArrayVec<[Worm; 3]>
}

#[derive(Debug, PartialEq, Eq)]
pub struct Worm {
    pub id: i32,
    pub health: i32,
    pub position: Point2d<i8>,
    pub weapon_damage: i32,
    pub weapon_range: u8
}

#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub enum Powerup {
    Health(Point2d<i8>, i32)
}

#[derive(Debug, PartialEq, Eq)]
pub struct Map {
    pub size: u8,
    /// This is 2d, each row is size long
    pub cells: ArrayVec<[CellType; 2048]>
}

#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub enum CellType {
    Air,
    Dirt,
    DeepSpace,
}

#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub enum SimulationOutcome {
    PlayerWon(usize),
    Draw,
    Continue,
}

impl GameBoard {
    pub fn new(json: json::State) -> GameBoard {
        let commando_damage = json.my_player.worms[0].weapon.damage;
        let commando_range = json.my_player.worms[0].weapon.range;

        let player = Player {
            active_worm: json.active_worm_index().unwrap(),
            worms: json.my_player.worms.iter().map(|w| Worm {
                id: w.id,
                health: w.health,
                position: Point2d::new(w.position.x, w.position.y),
                weapon_damage: commando_damage,
                weapon_range: commando_range
            }).collect()
        };

        let opponent = Player {
            active_worm: 0,
            worms: json.opponents.iter().flat_map(|o| &o.worms).map(|w| Worm {
                id: w.id,
                health: w.health,
                position: Point2d::new(w.position.x, w.position.y),
                weapon_damage: commando_damage,
                weapon_range: commando_range
            }).collect()
        };
            
        GameBoard {
            players: [player, opponent],
            powerups: json.map.iter().flatten().filter_map(|c| {
                c.powerup.clone().map(|p| Powerup::Health(Point2d::new(c.x, c.y), p.value))
            }).collect(),
            map: Map {
                size: json.map_size,
                cells: json.map.iter().flatten().map(|c| match c.cell_type {
                    json::CellType::Air => CellType::Air,
                    json::CellType::Dirt => CellType::Dirt,
                    json::CellType::DeepSpace => CellType::DeepSpace,
                }).collect()
            }
        }
    }

    pub fn update(&mut self, _json: json::State) {
        // TODO
        // What can change?
        // - Worm health (and dead worms die)
        // - Active worms += 1
        // - The worms may move
        // - The powerups may be taken
        // - The map cells may change from dirt to not dirt
    }

    pub fn simulate(&mut self, moves: [Command; 2]) -> SimulationOutcome {
        match moves {
            [Command::Move(x1, y1), Command::Move(x2, y2)] if x1 == x2 && y1 == y2 => {
                // TODO: Get this from some sort of config rather
                let damage = 20;


                debug_assert_eq!(Some(CellType::Air), self.map.at(Point2d::new(x1, y1)));
                // Worms have a 50% chance of swapping places
                // here. I'm treating that as an edge case that I
                // don't need to handle for now.
                for player in &mut self.players {
                    player.active_worm_mut().health -= damage;
                }
            },
            _ => {
                for player_index in 0..moves.len() {
                    if let Command::Move(x, y) = moves[player_index] {
                        debug_assert_eq!(Some(CellType::Air), self.map.at(Point2d::new(x, y)));

                        let worm = self.players[player_index].active_worm_mut();

                        debug_assert!(
                            (worm.position.x - x).abs() <= 1 &&
                                (worm.position.y - y).abs() <= 1
                        );

                        worm.position.x = x;
                        worm.position.y = y;
                    }
                }
            }
        }

        for player_index in 0..moves.len() {
            if let Command::Dig(x, y) = moves[player_index] {
                println!("Player {} is digging {}, {}", player_index, x, y);
                debug_assert!(
                    Some(CellType::Dirt) == self.map.at(Point2d::new(x, y)) ||
                        Some(CellType::Air) == self.map.at(Point2d::new(x, y))
                );
                debug_assert!{
                    (self.players[player_index].active_worm().position.x - x).abs() <= 1 &&
                        (self.players[player_index].active_worm().position.y - y).abs() <= 1
                };

                if let Some(c) = self.map.at_mut(Point2d::new(x, y)) {
                    *c = CellType::Air;
                }
            }
        }

        for player_index in 0..moves.len() {
            if let Command::Shoot(dir) = moves[player_index] {
                let (center, weapon_range, weapon_damage) = {
                    let worm = self.players[player_index].active_worm();
                    (worm.position, worm.weapon_range, worm.weapon_damage)
                };
                let diff = dir.as_vec();

                let range = if dir.is_diagonal() {
                    ((weapon_range as f32 + 1.) / 2f32.sqrt()).floor() as i8
                } else {
                    weapon_range as i8
                };

                for distance in 1..=range {
                    let target = center + diff * distance;
                    match self.map.at(target) {
                        Some(CellType::Air) => {
                            let target_worm: Option<&mut Worm> = self.players.iter_mut()
                                .flat_map(|p| p.worms.iter_mut())
                                .find(|w| w.position == target);
                            if let Some(target_worm) = target_worm {
                                target_worm.health -= weapon_damage;
                                break;
                            }
                        },
                        _ => break
                    }
                }
            }
        }

        for player in &mut self.players {
            // Remove dead worms
            for worm_index in (0..player.worms.len()).rev() {
                if player.worms[worm_index].health <= 0 {
                    player.worms.remove(worm_index);
                    if player.active_worm >= worm_index {
                        if player.active_worm > 0 {
                            player.active_worm -= 1;
                        } else {
                            player.active_worm = player.worms.len()-1;
                        }
                    }
                }
            }
            // Update the active worm
            player.active_worm = (player.active_worm + 1) % player.worms.len();
        }

        match (self.players[0].worms.len(), self.players[1].worms.len()) {
            (0, 0) => SimulationOutcome::Draw,
            (_, 0) => SimulationOutcome::PlayerWon(0),
            (0, _) => SimulationOutcome::PlayerWon(1),
            _ => SimulationOutcome::Continue
        }
    }
}

impl Player {
    pub fn find_worm(&self, id: i32) -> Option<&Worm> {
        self.worms
            .iter()
            .find(|w| w.id == id)
    }

    fn active_worm(&self) -> &Worm {
        &self.worms[self.active_worm]
    }

    fn active_worm_mut(&mut self) -> &mut Worm {
        &mut self.worms[self.active_worm]
    }
}

impl Map {
    fn at(&self, p: Point2d<i8>) -> Option<CellType> {
        if p.y < 0 || p.x < 0 || p.y as u8 >= self.size || p.x as u8 >= self.size {
            None
        } else {
            Some(self.cells[p.y as usize * self.size as usize + p.x as usize])
        }
    }

    fn at_mut(&mut self, p: Point2d<i8>) -> Option<&mut CellType> {
        if p.y < 0 || p.x < 0 || p.y as u8 >= self.size || p.x as u8 >= self.size {
            None
        } else {
            Some(&mut self.cells[p.y as usize * self.size as usize + p.x as usize])
        }
    }
}