use cgmath::{Deg, Point3};
use galactica_content as content;
use galactica_render::ObjectSubSprite;

/// Represents a gun attached to a specific ship at a certain gunpoint.
#[derive(Debug)]
pub struct ShipGun {
	/// The kind of gun this is
	pub kind: content::Gun,

	/// How many seconds we must wait before this gun can fire
	pub cooldown: f32,

	/// Index of the gunpoint this gun is attached to
	pub point: usize,
}

impl ShipGun {
	/// Make a new shipgun
	pub fn new(kind: &content::Gun, point: usize) -> Self {
		Self {
			kind: kind.clone(),
			point,
			cooldown: 0.0,
		}
	}
}

/// This struct keeps track of the combined stats of a set of outfits.
/// It does NOT check for sanity (e.g, removing an outfit that was never added)
/// That is handled by ShipOutfits.
#[derive(Debug)]
pub struct OutfitStatSum {
	pub engine_thrust: f32,
	pub steer_power: f32,
	pub engine_flare_textures: Vec<content::TextureHandle>,
}

impl OutfitStatSum {
	pub fn new() -> Self {
		Self {
			engine_thrust: 0.0,
			steer_power: 0.0,
			engine_flare_textures: Vec::new(),
		}
	}

	pub fn add(&mut self, o: &content::Outfit) {
		self.engine_thrust += o.engine_thrust;
		if let Some(t) = o.engine_flare_texture {
			self.engine_flare_textures.push(t);
		};
		self.steer_power += o.steer_power;
	}

	pub fn remove(&mut self, o: &content::Outfit) {
		self.engine_thrust -= o.engine_thrust;
		if let Some(t) = o.engine_flare_texture {
			self.engine_flare_textures.remove(
				self.engine_flare_textures
					.iter()
					.position(|x| *x == t)
					.unwrap(),
			);
		}
		self.steer_power -= o.steer_power;
	}
}

/// Represents a set of outfits attached to a ship.
/// Keeps track of the sum of their stats, so it mustn't be re-computed every frame.
#[derive(Debug)]
pub struct OutfitSet {
	/// The total sum of the stats this set of outfits provides
	/// TODO: this shouldn't be pub
	pub stats: OutfitStatSum,

	//pub total_space: content::OutfitSpace,
	available_space: content::OutfitSpace,
	outfits: Vec<content::OutfitHandle>,
	guns: Vec<ShipGun>,
	enginepoints: Vec<content::EnginePoint>,
	gunpoints: Vec<content::GunPoint>,

	// Minor performance optimization, since we
	// rarely need to re-compute these.
	engine_flare_sprites: Vec<ObjectSubSprite>,
}

impl<'a> OutfitSet {
	/// Make a new outfit array
	pub fn new(content: &content::Ship) -> Self {
		Self {
			stats: OutfitStatSum::new(),
			outfits: Vec::new(),
			guns: Vec::new(),
			available_space: content.space.clone(),
			//total_space: content.space.clone(),
			enginepoints: content.engines.clone(),
			gunpoints: content.guns.clone(),
			engine_flare_sprites: vec![],
		}
	}

	/// Does this outfit set contain the specified outfit?
	pub fn contains_outfit(&self, o: content::OutfitHandle) -> bool {
		match self.outfits.iter().position(|x| *x == o) {
			Some(_) => true,
			None => false,
		}
	}

	/// Add an outfit to this ship.
	/// Returns true on success, and false on failure
	/// TODO: failure reason enum
	pub fn add(&mut self, ct: &content::Content, o: content::OutfitHandle) -> bool {
		let outfit = ct.get_outfit(o);
		if !self.available_space.can_contain(&outfit.space) {
			return false;
		}
		self.available_space.occupy(&outfit.space);
		self.stats.add(&outfit);
		self.outfits.push(o);
		self.update_engine_flares();
		return true;
	}

	/// Remove an outfit from this set
	pub fn remove(&mut self, ct: &content::Content, o: content::OutfitHandle) {
		let outfit = ct.get_outfit(o);
		let i = match self.outfits.iter().position(|x| *x == o) {
			Some(i) => i,
			None => panic!("removed non-existing outfit"),
		};
		self.available_space.free(&outfit.space);
		self.outfits.remove(i);
		self.stats.remove(&outfit);
		self.update_engine_flares();
	}

	/// Add a gun to this outfit set.
	/// This automatically attaches the gun to the first available gunpoint,
	/// and returns false (applying no changes) if no points are available.
	pub fn add_gun(&mut self, ct: &content::Content, g: content::GunHandle) -> bool {
		// Find first unused point
		let mut p = None;
		'outer: for i in 0..self.gunpoints.len() {
			for g in &self.guns {
				if g.point == i {
					continue 'outer;
				}
			}
			p = Some(i);
			break;
		}
		let gun = ct.get_gun(g);

		// All points are taken
		if p.is_none() {
			return false;
		}

		let sg = ShipGun::new(gun, p.unwrap());
		self.guns.push(sg);
		return true;
	}

	/// Iterate over all guns in this outfitset
	pub fn iter_guns(&mut self) -> impl Iterator<Item = &mut ShipGun> {
		self.guns.iter_mut()
	}

	/// Iterate over all guns and the gunpoints they're attached to
	pub fn iter_guns_points(&mut self) -> impl Iterator<Item = (&mut ShipGun, &content::GunPoint)> {
		self.guns
			.iter_mut()
			.map(|x| (&self.gunpoints[x.point], x))
			.map(|(a, b)| (b, a))
	}

	/// Update engine flare sprites
	pub fn update_engine_flares(&mut self) {
		// TODO: better way to pick flare texture
		self.engine_flare_sprites.clear();
		let t = if let Some(e) = self.stats.engine_flare_textures.iter().next() {
			e
		} else {
			return;
		};

		self.engine_flare_sprites = self
			.enginepoints
			.iter()
			.map(|p| ObjectSubSprite {
				pos: Point3 {
					x: p.pos.x,
					y: p.pos.y,
					z: 1.0,
				},
				texture: *t,
				angle: Deg(0.0),
				size: p.size,
			})
			.collect();
	}

	/// Get the sprites we should show if this ship is firing its engines
	pub fn get_engine_flares(&self) -> Vec<ObjectSubSprite> {
		return self.engine_flare_sprites.clone();
	}
}