#![warn(missing_docs)]

//! This subcrate is responsible for loading, parsing, validating game content,
//! which is usually stored in `./content`.

mod handle;
mod part;
mod util;

use anyhow::{Context, Result};
use std::{
	collections::HashMap,
	fs::File,
	io::Read,
	path::{Path, PathBuf},
};
use toml;
use walkdir::WalkDir;

pub use handle::{FactionHandle, GunHandle, OutfitHandle, ShipHandle, SystemHandle, TextureHandle};
pub use part::{
	EnginePoint, Faction, Gun, GunPoint, Outfit, OutfitSpace, Projectile, Relationship, Ship,
	System, Texture,
};

mod syntax {
	use anyhow::{bail, Context, Result};
	use serde::Deserialize;
	use std::{collections::HashMap, fmt::Display, hash::Hash};

	use crate::part::{faction, gun, outfit, ship, system, texture};

	#[derive(Debug, Deserialize)]
	pub struct Root {
		pub gun: Option<HashMap<String, gun::syntax::Gun>>,
		pub ship: Option<HashMap<String, ship::syntax::Ship>>,
		pub system: Option<HashMap<String, system::syntax::System>>,
		pub outfit: Option<HashMap<String, outfit::syntax::Outfit>>,
		pub texture: Option<HashMap<String, texture::syntax::Texture>>,
		pub faction: Option<HashMap<String, faction::syntax::Faction>>,
	}

	fn merge_hashmap<K, V>(
		to: &mut Option<HashMap<K, V>>,
		mut from: Option<HashMap<K, V>>,
	) -> Result<()>
	where
		K: Hash + Eq + Display,
	{
		if to.is_none() {
			*to = from.take();
			return Ok(());
		}

		if let Some(from_inner) = from {
			let to_inner = to.as_mut().unwrap();
			for (k, v) in from_inner {
				if to_inner.contains_key(&k) {
					bail!("Found duplicate key `{k}`");
				} else {
					to_inner.insert(k, v);
				}
			}
		}
		return Ok(());
	}

	impl Root {
		pub fn new() -> Self {
			Self {
				gun: None,
				ship: None,
				system: None,
				outfit: None,
				texture: None,
				faction: None,
			}
		}

		pub fn merge(&mut self, other: Root) -> Result<()> {
			merge_hashmap(&mut self.gun, other.gun).with_context(|| "while merging guns")?;
			merge_hashmap(&mut self.ship, other.ship).with_context(|| "while merging ships")?;
			merge_hashmap(&mut self.system, other.system)
				.with_context(|| "while merging systems")?;
			merge_hashmap(&mut self.outfit, other.outfit)
				.with_context(|| "while merging outfits")?;
			merge_hashmap(&mut self.texture, other.texture)
				.with_context(|| "while merging textures")?;
			merge_hashmap(&mut self.faction, other.faction)
				.with_context(|| "while merging factions")?;
			return Ok(());
		}
	}
}

trait Build {
	type InputSyntax;

	/// Build a processed System struct from raw serde data
	fn build(root: Self::InputSyntax, ct: &mut Content) -> Result<()>
	where
		Self: Sized;
}

/// Represents static game content
#[derive(Debug)]
pub struct Content {
	/* Configuration values */
	/// Root directory for textures
	texture_root: PathBuf,
	/// Name of starfield texture
	starfield_texture_name: String,

	/// Textures
	pub textures: Vec<part::texture::Texture>,
	texture_index: HashMap<String, handle::TextureHandle>,
	/// The texture to use for starfield stars
	starfield_handle: Option<handle::TextureHandle>,

	/// Outfits
	outfits: Vec<part::outfit::Outfit>,

	/// Ship guns
	guns: Vec<part::gun::Gun>,

	/// Ship bodies
	ships: Vec<part::ship::Ship>,

	/// Star systems
	pub systems: Vec<part::system::System>,

	/// Factions
	factions: Vec<part::faction::Faction>,
}

// Loading methods
impl Content {
	fn try_parse(path: &Path) -> Result<syntax::Root> {
		let mut file_string = String::new();
		let _ = File::open(path)?.read_to_string(&mut file_string);
		let file_string = file_string.trim();
		return Ok(toml::from_str(&file_string)?);
	}

	/// Load content from a directory.
	pub fn load_dir(
		path: PathBuf,
		texture_root: PathBuf,
		starfield_texture_name: String,
	) -> Result<Self> {
		let mut root = syntax::Root::new();

		for e in WalkDir::new(path).into_iter().filter_map(|e| e.ok()) {
			if e.metadata().unwrap().is_file() {
				// TODO: better warnings
				match e.path().extension() {
					Some(t) => {
						if t.to_str() != Some("toml") {
							println!("[WARNING] {e:#?} is not a toml file, skipping.");
							continue;
						}
					}
					None => {
						println!("[WARNING] {e:#?} is not a toml file, skipping.");
						continue;
					}
				}

				let path = e.path();
				let this_root = Self::try_parse(path)
					.with_context(|| format!("Could not read {}", path.display()))?;

				root.merge(this_root)
					.with_context(|| format!("Could not parse {}", path.display()))?;
			}
		}

		let mut content = Self {
			systems: Vec::new(),
			ships: Vec::new(),
			guns: Vec::new(),
			outfits: Vec::new(),
			textures: Vec::new(),
			factions: Vec::new(),
			texture_index: HashMap::new(),
			starfield_handle: None,
			texture_root,
			starfield_texture_name,
		};

		// Order here matters, usually
		if root.texture.is_some() {
			part::texture::Texture::build(root.texture.take().unwrap(), &mut content)?;
		}
		if root.ship.is_some() {
			part::ship::Ship::build(root.ship.take().unwrap(), &mut content)?;
		}
		if root.gun.is_some() {
			part::gun::Gun::build(root.gun.take().unwrap(), &mut content)?;
		}
		if root.outfit.is_some() {
			part::outfit::Outfit::build(root.outfit.take().unwrap(), &mut content)?;
		}
		if root.system.is_some() {
			part::system::System::build(root.system.take().unwrap(), &mut content)?;
		}
		if root.faction.is_some() {
			part::faction::Faction::build(root.faction.take().unwrap(), &mut content)?;
		}

		return Ok(content);
	}
}

// Access methods
impl Content {
	/// Get the texture handle for the starfield texture
	pub fn get_starfield_handle(&self) -> TextureHandle {
		match self.starfield_handle {
			Some(h) => h,
			None => unreachable!("Starfield texture hasn't been loaded yet!"),
		}
	}

	/// Get a handle from a texture name
	pub fn get_texture_handle(&self, name: &str) -> TextureHandle {
		return match self.texture_index.get(name) {
			Some(s) => *s,
			None => unreachable!("get_texture_handle was called with a bad handle!"),
		};
	}

	/// Get a texture from a handle
	pub fn get_texture(&self, h: TextureHandle) -> &Texture {
		// In theory, this could fail if h has a bad index, but that shouldn't ever happen.
		// The only TextureHandles that exist should be created by this crate.
		return &self.textures[h.index];
	}

	/// Get an outfit from a handle
	pub fn get_outfit(&self, h: OutfitHandle) -> &Outfit {
		return &self.outfits[h.index];
	}

	/// Get a gun from a handle
	pub fn get_gun(&self, h: GunHandle) -> &Gun {
		return &self.guns[h.index];
	}

	/// Get a texture from a handle
	pub fn get_ship(&self, h: ShipHandle) -> &Ship {
		return &self.ships[h.index];
	}

	/// Get a system from a handle
	pub fn get_system(&self, h: SystemHandle) -> &System {
		return &self.systems[h.index];
	}

	/// Get a faction from a handle
	pub fn get_faction(&self, h: FactionHandle) -> &Faction {
		return &self.factions[h.index];
	}
}