use anyhow::{Context, Result};
use std::collections::HashMap;

use crate::{handle::SpriteHandle, Content, ContentBuildContext, EffectHandle};

pub(crate) mod syntax {
	use anyhow::{bail, Result};
	use galactica_util::to_radians;
	use serde::Deserialize;

	use crate::{Content, ContentBuildContext, EffectHandle, StartEdge};
	// Raw serde syntax structs.
	// These are never seen by code outside this crate.

	#[derive(Debug, Deserialize)]
	pub struct Effect {
		pub sprite: String,
		pub size: f32,
		pub size_rng: Option<f32>,
		pub lifetime: TextOrFloat,
		pub lifetime_rng: Option<f32>,
		pub angle: Option<f32>,
		pub angle_rng: Option<f32>,
		pub angvel: Option<f32>,
		pub angvel_rng: Option<f32>,
		pub velocity_scale_parent: Option<f32>,
		pub velocity_scale_parent_rng: Option<f32>,
		pub velocity_scale_target: Option<f32>,
		pub velocity_scale_target_rng: Option<f32>,
		pub direction_rng: Option<f32>,
		pub fade: Option<f32>,
		pub fade_rng: Option<f32>,
	}

	#[derive(Debug, Deserialize)]
	#[serde(untagged)]
	pub enum TextOrFloat {
		Text(String),
		Float(f32),
	}

	// We implement building here instead of in super::Effect because
	// effects may be defined inline (see EffectReference).
	impl Effect {
		pub fn add_to(
			self,
			_build_context: &mut ContentBuildContext,
			content: &mut Content,
		) -> Result<EffectHandle> {
			let sprite = match content.sprite_index.get(&self.sprite) {
				None => bail!("sprite `{}` doesn't exist", self.sprite),
				Some(t) => *t,
			};

			let lifetime = match self.lifetime {
				TextOrFloat::Float(f) => f,
				TextOrFloat::Text(s) => {
					if s == "inherit" {
						// Match lifetime of first section of sprite
						let sprite = content.get_sprite(sprite);
						let sec = match sprite.start_at {
							StartEdge::Top { section } => sprite.get_section(section),
							StartEdge::Bot { section } => sprite.get_section(section),
						};
						sec.frame_duration * sec.frames.len() as f32
					} else {
						bail!("bad effect lifetime, must be float or \"inherit\"",)
					}
				}
			};

			let handle = EffectHandle {
				index: content.effects.len(),
			};
			content.effects.push(super::Effect {
				handle,
				sprite,
				size: self.size,
				size_rng: self.size_rng.unwrap_or(0.0),
				lifetime,
				lifetime_rng: self.lifetime_rng.unwrap_or(0.0),
				angle: to_radians(self.angle.unwrap_or(0.0) / 2.0),
				angle_rng: to_radians(self.angle_rng.unwrap_or(0.0) / 2.0),
				angvel: to_radians(self.angvel.unwrap_or(0.0)),
				angvel_rng: to_radians(self.angvel_rng.unwrap_or(0.0)),
				velocity_scale_parent: self.velocity_scale_parent.unwrap_or(0.0),
				velocity_scale_parent_rng: self.velocity_scale_parent_rng.unwrap_or(0.0),
				velocity_scale_target: self.velocity_scale_target.unwrap_or(0.0),
				velocity_scale_target_rng: self.velocity_scale_target_rng.unwrap_or(0.0),
				direction_rng: self.direction_rng.unwrap_or(0.0) / 2.0,
				fade: self.fade.unwrap_or(0.0),
				fade_rng: self.fade_rng.unwrap_or(0.0),
			});

			return Ok(handle);
		}
	}

	// This isn't used here, but is pulled in by other content items.
	/// A reference to an effect by name, or an inline definition.
	#[derive(Debug, Deserialize)]
	#[serde(untagged)]
	pub enum EffectReference {
		Label(String),
		Effect(Effect),
	}

	impl EffectReference {
		pub fn to_handle(
			self,
			build_context: &mut ContentBuildContext,
			content: &mut Content,
		) -> Result<EffectHandle> {
			// We do not insert anything into build_context here,
			// since inline effects cannot be referenced by name.
			Ok(match self {
				Self::Effect(e) => e.add_to(build_context, content)?,
				Self::Label(l) => match build_context.effect_index.get(&l) {
					Some(h) => *h,
					None => bail!("no effect named `{}`", l),
				},
			})
		}
	}
}

/// The effect a projectile will spawn when it hits something
#[derive(Debug, Clone)]
pub struct Effect {
	/// This effect's handle
	pub handle: EffectHandle,

	/// The sprite to use for this effect.
	pub sprite: SpriteHandle,

	/// The height of this effect, in game units.
	pub size: f32,

	/// Random size variation
	pub size_rng: f32,

	/// How many seconds this effect should live
	pub lifetime: f32,

	/// Random lifetime variation
	pub lifetime_rng: f32,

	/// The angle this effect points once spawned, in radians
	pub angle: f32,

	/// Random angle variation, in radians
	pub angle_rng: f32,

	/// How fast this effect spins, in radians/sec
	pub angvel: f32,

	/// Random angvel variation
	pub angvel_rng: f32,

	/// The amount of this effect's parent's velocity to inherit
	pub velocity_scale_parent: f32,

	/// Parent velocity random variation
	pub velocity_scale_parent_rng: f32,

	/// The amount of this effect's parent's target velocity to inherit.
	/// If there is no target, this is zero.
	pub velocity_scale_target: f32,

	/// Target velocity random variation
	pub velocity_scale_target_rng: f32,

	/// Travel direction random variation
	pub direction_rng: f32,

	/// Fade this effect out over this many seconds as it ends
	pub fade: f32,

	/// Random fade ariation
	pub fade_rng: f32,
}

impl crate::Build for Effect {
	type InputSyntaxType = HashMap<String, syntax::Effect>;

	fn build(
		effects: Self::InputSyntaxType,
		build_context: &mut ContentBuildContext,
		content: &mut Content,
	) -> Result<()> {
		for (effect_name, effect) in effects {
			let h = effect
				.add_to(build_context, content)
				.with_context(|| format!("while evaluating effect `{}`", effect_name))?;
			build_context.effect_index.insert(effect_name, h);
		}

		return Ok(());
	}
}