#![warn(missing_docs)]

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

mod handle;
mod part;
mod spriteautomaton;
mod util;

use anyhow::{bail, Context, Result};
use galactica_packer::{SpriteAtlas, SpriteAtlasImage};
use std::{
	collections::HashMap,
	fs::File,
	io::Read,
	num::NonZeroU32,
	path::{Path, PathBuf},
};
use toml;
use walkdir::WalkDir;

pub use handle::*;
pub use part::*;
pub use spriteautomaton::*;

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

	use crate::{
		config,
		part::{effect, faction, outfit, ship, sprite, system},
	};

	#[derive(Debug, Deserialize)]
	pub struct Root {
		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 sprite: Option<HashMap<String, sprite::syntax::Sprite>>,
		pub faction: Option<HashMap<String, faction::syntax::Faction>>,
		pub effect: Option<HashMap<String, effect::syntax::Effect>>,
		pub config: Option<config::syntax::Config>,
	}

	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 {
				ship: None,
				system: None,
				outfit: None,
				sprite: None,
				faction: None,
				effect: None,
				config: None,
			}
		}

		pub fn merge(&mut self, other: Root) -> Result<()> {
			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.sprite, other.sprite)
				.with_context(|| "while merging sprites")?;
			merge_hashmap(&mut self.faction, other.faction)
				.with_context(|| "while merging factions")?;
			merge_hashmap(&mut self.effect, other.effect)
				.with_context(|| "while merging effects")?;
			if self.config.is_some() {
				if other.config.is_some() {
					bail!("invalid content dir, multiple config tables")
				}
			} else {
				self.config = other.config;
			}
			return Ok(());
		}
	}
}

trait Build {
	type InputSyntaxType;

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

/// Stores temporary data while building context objects
#[derive(Debug)]
pub(crate) struct ContentBuildContext {
	/// Map effect names to handles
	pub effect_index: HashMap<String, EffectHandle>,

	/// Maps sprite handles to a map of section name -> section index
	pub sprite_section_index: HashMap<SpriteHandle, HashMap<String, AnimSectionHandle>>,
}

impl ContentBuildContext {
	fn new() -> Self {
		Self {
			effect_index: HashMap::new(),
			sprite_section_index: HashMap::new(),
		}
	}
}

/// Represents static game content
#[derive(Debug, Clone)]
pub struct Content {
	/// Sprites
	pub sprites: Vec<Sprite>,
	/// Map strings to texture names.
	/// This is only necessary because we need to hard-code a few texture names for UI elements.
	sprite_index: HashMap<String, SpriteHandle>,

	/// Keeps track of which images are in which texture
	sprite_atlas: SpriteAtlas,

	outfits: Vec<Outfit>,
	guns: Vec<Gun>, // TODO: merge with outfit
	ships: Vec<Ship>,
	systems: Vec<System>,
	factions: Vec<Faction>,
	effects: Vec<Effect>,
	config: Config,
}

// 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, asset_root: PathBuf, atlas_index: PathBuf) -> 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 atlas: SpriteAtlas = {
			let mut file_string = String::new();
			let _ = File::open(atlas_index)?.read_to_string(&mut file_string);
			let file_string = file_string.trim();
			toml::from_str(&file_string)?
		};

		let mut build_context = ContentBuildContext::new();

		let mut content = Self {
			config: {
				if let Some(c) = root.config {
					c.build(&asset_root, &atlas)
						.with_context(|| "while parsing config table")?
				} else {
					bail!("failed loading content: no config table specified")
				}
			},

			sprite_atlas: atlas,
			systems: Vec::new(),
			ships: Vec::new(),
			guns: Vec::new(),
			outfits: Vec::new(),
			sprites: Vec::new(),
			factions: Vec::new(),
			effects: Vec::new(),
			sprite_index: HashMap::new(),
		};

		// TODO: enforce sprite and image limits

		// Order matters. Some content types require another to be fully initialized
		if root.sprite.is_some() {
			part::sprite::Sprite::build(
				root.sprite.take().unwrap(),
				&mut build_context,
				&mut content,
			)?;
		}
		if root.effect.is_some() {
			part::effect::Effect::build(
				root.effect.take().unwrap(),
				&mut build_context,
				&mut content,
			)?;
		}

		// Order below this line does not matter
		if root.ship.is_some() {
			part::ship::Ship::build(root.ship.take().unwrap(), &mut build_context, &mut content)?;
		}
		if root.outfit.is_some() {
			part::outfit::Outfit::build(
				root.outfit.take().unwrap(),
				&mut build_context,
				&mut content,
			)?;
		}
		if root.system.is_some() {
			part::system::System::build(
				root.system.take().unwrap(),
				&mut build_context,
				&mut content,
			)?;
		}
		if root.faction.is_some() {
			part::faction::Faction::build(
				root.faction.take().unwrap(),
				&mut build_context,
				&mut content,
			)?;
		}

		return Ok(content);
	}
}

// Access methods
impl Content {
	/// Iterate over all valid system handles
	pub fn iter_systems(&self) -> impl Iterator<Item = SystemHandle> {
		(0..self.systems.len()).map(|x| SystemHandle { index: x })
	}

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

	/// Get a sprite from a handle
	pub fn get_sprite(&self, h: SpriteHandle) -> &Sprite {
		// In theory, this could fail if h has a bad index, but that shouldn't ever happen.
		// The only handles that exist should be created by this crate.
		return &self.sprites[h.index as usize];
	}

	/// Get the list of atlas files we may use
	pub fn atlas_files(&self) -> &Vec<String> {
		return &self.sprite_atlas.atlas_list;
	}

	/// Get sprite atlas metadata
	pub fn get_atlas(&self) -> &SpriteAtlas {
		return &self.sprite_atlas;
	}

	/// Get a texture by its index
	pub fn get_image(&self, idx: NonZeroU32) -> &SpriteAtlasImage {
		&self.sprite_atlas.get_by_idx(idx)
	}

	/// 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 ship 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 system object from a handle
	pub fn get_system_object(&self, h: SystemObjectHandle) -> &SystemObject {
		return &self.get_system(h.system_handle).objects[h.body_index];
	}

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

	/// Get an effect from a handle
	pub fn get_effect(&self, h: EffectHandle) -> &Effect {
		return &self.effects[h.index];
	}

	/// Get content configuration
	pub fn get_config(&self) -> &Config {
		return &self.config;
	}
}