use std::collections::HashMap;

use content::{GunPoint, OutfitHandle, OutfitSpace};
use galactica_content as content;

/// Possible outcomes when adding an outfit
pub enum OutfitAddResult {
	/// An outfit was successfully added
	Ok,

	/// An outfit could not be added because we don't have enough free space.
	/// The string tells us what kind of space we need:
	/// `outfit,` `weapon,` `engine,` etc. Note that these sometimes overlap:
	/// outfits may need outfit AND weapon space. In these cases, this result
	/// should name the "most specific" kind of space we lack.
	NotEnoughSpace(String),
}

/// Possible outcomes when removing an outfit
pub enum OutfitRemoveResult {
	/// This outfit was successfully removed
	Ok,

	/// This outfit isn't in this set
	NotExist,
	// TODO:
	// This is where we'll add non-removable outfits,
	// outfits that provide space, etc
}

/// A simple data class, used to keep track of delayed shield generators
#[derive(Debug)]
pub(crate) struct ShieldGenerator {
	pub outfit: OutfitHandle,
	pub delay: f32,
	pub generation: f32,
}

/// This struct keeps track of a ship's outfit loadout.
#[derive(Debug)]
pub struct OutfitSet {
	/// What outfits does this statsum contain?
	outfits: HashMap<OutfitHandle, u32>,

	/// Space available in this outfitset.
	/// set at creation and never changes.
	total_space: OutfitSpace,

	/// Space used by the outfits in this set.
	/// This may be negative if certain outfits provide space!
	used_space: OutfitSpace,

	/// The gun points available in this ship.
	/// If value is None, this point is free.
	/// if value is Some, this point is taken.
	gun_points: HashMap<GunPoint, Option<OutfitHandle>>,

	// Outfit values
	// This isn't strictly necessary, but we don't want to
	// re-compute this on each frame.
	engine_thrust: f32,
	steer_power: f32,
	shield_strength: f32,

	// Delay, generation
	// TODO: struct
	shield_generators: Vec<ShieldGenerator>,
}

impl OutfitSet {
	pub fn new(available_space: OutfitSpace, gun_points: &[GunPoint]) -> Self {
		Self {
			outfits: HashMap::new(),
			total_space: available_space,
			used_space: OutfitSpace::new(),
			gun_points: gun_points.iter().map(|x| (x.clone(), None)).collect(),

			engine_thrust: 0.0,
			steer_power: 0.0,
			shield_strength: 0.0,
			shield_generators: Vec::new(),
		}
	}

	pub fn add(&mut self, o: &content::Outfit) -> OutfitAddResult {
		if !(self.total_space - self.used_space).can_contain(&o.space) {
			return OutfitAddResult::NotEnoughSpace("TODO".to_string());
		}

		self.used_space += o.space;

		self.engine_thrust += o.engine_thrust;
		self.steer_power += o.steer_power;
		self.shield_strength += o.shield_strength;
		self.shield_generators.push(ShieldGenerator {
			outfit: o.handle,
			delay: o.shield_delay,
			generation: o.shield_generation,
		});

		return OutfitAddResult::Ok;
	}

	pub fn remove(&mut self, o: &content::Outfit) -> OutfitRemoveResult {
		if !self.outfits.contains_key(&o.handle) {
			return OutfitRemoveResult::NotExist;
		} else {
			let n = *self.outfits.get(&o.handle).unwrap();
			if n == 1u32 {
				self.outfits.remove(&o.handle);
			} else {
				*self.outfits.get_mut(&o.handle).unwrap() -= 1;
			}
		}

		self.used_space -= o.space;

		self.engine_thrust -= o.engine_thrust;
		self.steer_power -= o.steer_power;
		self.shield_strength -= o.shield_strength;

		{
			// This index will exist, since we checked the hashmap
			let index = self
				.shield_generators
				.iter()
				.position(|g| g.outfit == o.handle)
				.unwrap();
			self.shield_generators.remove(index);
		}

		return OutfitRemoveResult::Ok;
	}
}

// Simple getters to make sure nobody meddles with our internal state
impl OutfitSet {
	/// The number of outfits in this set
	pub fn len(&self) -> u32 {
		self.outfits.iter().map(|(_, x)| x).sum()
	}

	/// Iterate over all outfits
	pub fn iter_outfits(&self) -> impl Iterator<Item = (&OutfitHandle, &u32)> {
		self.outfits.iter()
	}

	/// Iterate over all gun points
	pub fn iter_gun_points(&self) -> impl Iterator<Item = (&GunPoint, &Option<OutfitHandle>)> {
		self.gun_points.iter()
	}

	/// Iterate over all shield generators
	pub(crate) fn iter_shield_generators(&self) -> impl Iterator<Item = &ShieldGenerator> {
		self.shield_generators.iter()
	}

	/// Get maximum possible shield regen
	pub fn get_max_shield_regen(&self) -> f32 {
		self.shield_generators.iter().map(|x| x.generation).sum()
	}

	/// Total available outfit space
	pub fn get_total_space(&self) -> &OutfitSpace {
		&self.total_space
	}

	/// Used outfit space
	pub fn get_used_space(&self) -> &OutfitSpace {
		&self.used_space
	}

	/// Total foward thrust
	pub fn get_engine_thrust(&self) -> f32 {
		self.engine_thrust
	}

	/// Total steer power
	pub fn get_steer_power(&self) -> f32 {
		self.steer_power
	}

	/// Total shield strength
	pub fn get_shield_strength(&self) -> f32 {
		self.shield_strength
	}
}