use ecs::sole::Single;

use crate::asset::{
    Asset,
    Assets,
    Dependency as AssetDependency,
    Event as AssetEvent,
    Events as AssetEvents,
    Handle as AssetHandle,
    Label as AssetLabel,
};
use crate::builder;
use crate::color::{Color, Rgb};
use crate::ecs::Component;
use crate::reflection::Reflection;
use crate::texture::Texture;

pub mod asset;

#[derive(Debug, Clone)]
#[non_exhaustive]
pub struct Material
{
    pub ambient: Color<f32>,
    pub diffuse: Color<f32>,
    pub specular: Color<f32>,
    pub ambient_map: Option<AssetHandle<Texture>>,
    pub diffuse_map: Option<AssetHandle<Texture>>,
    pub specular_map: Option<AssetHandle<Texture>>,
    pub shininess: f32,
    pub loading_textures: Vec<(LoadingTextureName, AssetLabel<'static>)>,
}

impl Material
{
    #[must_use]
    pub fn builder() -> Builder
    {
        Builder::new()
    }

    pub fn textures(&self) -> impl Iterator<Item = &AssetHandle<Texture>>
    {
        [&self.ambient_map, &self.diffuse_map, &self.specular_map]
            .into_iter()
            .flatten()
    }
}

impl Default for Material
{
    fn default() -> Self
    {
        Self::builder().build()
    }
}

impl Asset for Material
{
    fn dependencies(&self) -> impl Iterator<Item = AssetDependency<'_>>
    {
        self.loading_textures.iter().map(|(_, texture_label)| {
            AssetDependency::new::<Texture>(AssetLabel {
                path: (&*texture_label.path).into(),
                name: texture_label.name.as_deref().map(Into::into),
            })
        })
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[non_exhaustive]
pub enum LoadingTextureName
{
    AmbientMap,
    DiffuseMap,
    SpecularMap,
}

/// [`Material`] builder.
#[derive(Debug, Clone)]
pub struct Builder
{
    ambient: Color<f32>,
    diffuse: Color<f32>,
    specular: Color<f32>,
    ambient_map: Option<AssetHandle<Texture>>,
    diffuse_map: Option<AssetHandle<Texture>>,
    specular_map: Option<AssetHandle<Texture>>,
    shininess: f32,
    loading_textures: Vec<(LoadingTextureName, AssetLabel<'static>)>,
}

impl Builder
{
    #[must_use]
    pub fn new() -> Self
    {
        Self {
            ambient: Color::Rgb(Rgb::<f32>::white()),
            diffuse: Color::Rgb(Rgb::<f32>::white()),
            specular: Color::Rgb(Rgb::<f32>::white()),
            ambient_map: None,
            diffuse_map: None,
            specular_map: None,
            shininess: 32.0,
            loading_textures: Vec::with_capacity(3),
        }
    }

    #[must_use]
    pub fn ambient(mut self, ambient: Color<f32>) -> Self
    {
        self.ambient = ambient;

        self
    }

    #[must_use]
    pub fn diffuse(mut self, diffuse: Color<f32>) -> Self
    {
        self.diffuse = diffuse;

        self
    }

    #[must_use]
    pub fn specular(mut self, specular: Color<f32>) -> Self
    {
        self.specular = specular;

        self
    }

    #[must_use]
    pub fn ambient_map(mut self, ambient_map: AssetHandle<Texture>) -> Self
    {
        self.ambient_map = Some(ambient_map);

        self
    }

    #[must_use]
    pub fn diffuse_map(mut self, diffuse_map: AssetHandle<Texture>) -> Self
    {
        self.diffuse_map = Some(diffuse_map);

        self
    }

    #[must_use]
    pub fn specular_map(mut self, specular_map: AssetHandle<Texture>) -> Self
    {
        self.specular_map = Some(specular_map);

        self
    }

    #[must_use]
    pub fn loading_texture(
        mut self,
        name: LoadingTextureName,
        asset_label: AssetLabel<'static>,
    ) -> Self
    {
        self.loading_textures.push((name, asset_label));
        self
    }

    #[must_use]
    pub fn shininess(mut self, shininess: f32) -> Self
    {
        self.shininess = shininess;

        self
    }

    /// Builds a new [`Material`].
    #[must_use]
    pub fn build(self) -> Material
    {
        Material {
            ambient: self.ambient,
            diffuse: self.diffuse,
            specular: self.specular,
            ambient_map: self.ambient_map,
            diffuse_map: self.diffuse_map,
            specular_map: self.specular_map,
            shininess: self.shininess,
            loading_textures: self.loading_textures,
        }
    }
}

impl Default for Builder
{
    fn default() -> Self
    {
        Self::new()
    }
}

builder! {
/// Material flags.
#[builder(name = FlagsBuilder, derives = (Debug, Clone))]
#[derive(Debug, Clone, Component, Reflection)]
#[non_exhaustive]
pub struct Flags
{
    /// Whether to use material's ambient color instead of the global ambient color.
    /// Default is `false`
    pub use_ambient_color: bool,
}
}

impl Flags
{
    #[must_use]
    pub const fn builder() -> FlagsBuilder
    {
        FlagsBuilder::new()
    }
}

impl Default for Flags
{
    fn default() -> Self
    {
        Self::builder().build()
    }
}

impl FlagsBuilder
{
    #[must_use]
    pub const fn new() -> Self
    {
        Self { use_ambient_color: false }
    }
}

impl Default for FlagsBuilder
{
    fn default() -> Self
    {
        Self::new()
    }
}

pub(crate) fn set_stored_materials_texture_handles(
    mut assets: Single<Assets>,
    asset_events: Single<AssetEvents>,
)
{
    let assets = assets.get_mut().unwrap();
    let asset_events = asset_events.get().unwrap();

    for AssetEvent::Stored(asset_id, ..) in asset_events.iter_last_tick() {
        let asset_handle = AssetHandle::<Material>::from_id(*asset_id);

        if !assets.is_loaded_and_has_type(&asset_handle) {
            continue;
        }

        let Some(material_textures) = assets.get(&asset_handle).map(|mat| {
            mat.loading_textures
                .iter()
                .map(|(tex_name, tex_label)| {
                    (
                        *tex_name,
                        assets.get_handle_to_loaded::<Texture>(tex_label.clone()),
                    )
                })
                .collect::<Vec<_>>()
        }) else {
            unreachable!();
        };

        let Some(material) = assets.get_mut(&asset_handle) else {
            unreachable!();
        };

        for (tex_name, tex_asset) in material_textures {
            let Some(tex_asset) = tex_asset else {
                unreachable!();
            };

            let dst = match tex_name {
                LoadingTextureName::AmbientMap => &mut material.ambient_map,
                LoadingTextureName::DiffuseMap => &mut material.diffuse_map,
                LoadingTextureName::SpecularMap => &mut material.specular_map,
            };

            *dst = Some(tex_asset);
        }
    }
}