/*!

[Wavefront OBJ][obj] parser for Rust. It handles both `.obj` and `.mtl` formats. [GitHub][]

```rust
use std::fs::File;
use std::io::BufReader;
use obj::{load_obj, Obj};

let input = BufReader::new(File::open("tests/fixtures/normal-cone.obj")?);
let dome: Obj = load_obj(input)?;

// Do whatever you want
dome.vertices;
dome.indices;
# Ok::<(), obj::ObjError>(())
```

<img src="https://simnalamburt.github.io/obj-rs/screenshot.png" style="max-width:100%">

[obj]: https://en.wikipedia.org/wiki/Wavefront_.obj_file
[GitHub]: https://github.com/simnalamburt/obj-rs

*/

#![deny(missing_docs)]

#[macro_use]
mod error;
pub mod raw;

pub use crate::error::{LoadError, LoadErrorKind, ObjError, ObjResult};

use crate::raw::object::Polygon;
use num_traits::FromPrimitive;
use std::collections::hash_map::{Entry, HashMap};
use std::io::BufRead;

#[cfg(feature = "glium")]
use glium::implement_vertex;
#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};

#[cfg(feature = "vulkano")]
#[cfg_attr(feature = "vulkano", macro_use)]
extern crate vulkano;

/// Load a wavefront OBJ file into Rust & OpenGL friendly format.
pub fn load_obj<V: FromRawVertex<I>, T: BufRead, I>(input: T) -> ObjResult<Obj<V, I>> {
    let raw = raw::parse_obj(input)?;
    Obj::new(raw)
}

/// 3D model object loaded from wavefront OBJ.
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct Obj<V = Vertex, I = u16> {
    /// Object's name.
    pub name: Option<String>,
    /// Vertex buffer.
    pub vertices: Vec<V>,
    /// Index buffer.
    pub indices: Vec<I>,
}

impl<V: FromRawVertex<I>, I> Obj<V, I> {
    /// Create `Obj` from `RawObj` object.
    pub fn new(raw: raw::RawObj) -> ObjResult<Self> {
        let (vertices, indices) =
            FromRawVertex::process(raw.positions, raw.normals, raw.tex_coords, raw.polygons)?;

        Ok(Obj {
            name: raw.name,
            vertices,
            indices,
        })
    }
}

/// Conversion from `RawObj`'s raw data.
pub trait FromRawVertex<I>: Sized {
    /// Build vertex and index buffer from raw object data.
    fn process(
        vertices: Vec<(f32, f32, f32, f32)>,
        normals: Vec<(f32, f32, f32)>,
        tex_coords: Vec<(f32, f32, f32)>,
        polygons: Vec<Polygon>,
    ) -> ObjResult<(Vec<Self>, Vec<I>)>;
}

/// Vertex data type of `Obj` which contains position and normal data of a vertex.
#[derive(Copy, PartialEq, Clone, Debug)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "vulkano", derive(Default))]
pub struct Vertex {
    /// Position vector of a vertex.
    pub position: [f32; 3],
    /// Normal vertor of a vertex.
    pub normal: [f32; 3],
}

#[cfg(feature = "glium")]
implement_vertex!(Vertex, position, normal);
#[cfg(feature = "vulkano")]
impl_vertex!(Vertex, position, normal);

impl<I: FromPrimitive + Copy> FromRawVertex<I> for Vertex {
    fn process(
        positions: Vec<(f32, f32, f32, f32)>,
        normals: Vec<(f32, f32, f32)>,
        _: Vec<(f32, f32, f32)>,
        polygons: Vec<Polygon>,
    ) -> ObjResult<(Vec<Self>, Vec<I>)> {
        let mut vb = Vec::with_capacity(polygons.len() * 3);
        let mut ib = Vec::with_capacity(polygons.len() * 3);
        {
            let mut cache = HashMap::new();
            let mut map = |pi: usize, ni: usize| {
                // Look up cache
                let index = match cache.entry((pi, ni)) {
                    // Cache miss -> make new, store it on cache
                    Entry::Vacant(entry) => {
                        let p = positions[pi];
                        let n = normals[ni];
                        let vertex = Vertex {
                            position: [p.0, p.1, p.2],
                            normal: [n.0, n.1, n.2],
                        };
                        let index = I::from_usize(vb.len())
                            .expect("Unable to convert the index from usize");
                        vb.push(vertex);
                        entry.insert(index);
                        index
                    }
                    // Cache hit -> use it
                    Entry::Occupied(entry) => *entry.get(),
                };
                ib.push(index)
            };

            for polygon in polygons {
                match polygon {
                    Polygon::P(_) | Polygon::PT(_) => make_error!(
                        InsufficientData,
                        "Tried to extract normal data which are not contained in the model"
                    ),
                    Polygon::PN(ref vec) if vec.len() == 3 => {
                        for &(pi, ni) in vec {
                            map(pi, ni)
                        }
                    }
                    Polygon::PTN(ref vec) if vec.len() == 3 => {
                        for &(pi, _, ni) in vec {
                            map(pi, ni)
                        }
                    }
                    _ => make_error!(
                        UntriangulatedModel,
                        "Model should be triangulated first to be loaded properly"
                    ),
                }
            }
        }
        vb.shrink_to_fit();
        Ok((vb, ib))
    }
}

/// Vertex data type of `Obj` which contains only position data of a vertex.
#[derive(Copy, PartialEq, Clone, Debug)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "vulkano", derive(Default))]
pub struct Position {
    /// Position vector of a vertex.
    pub position: [f32; 3],
}

#[cfg(feature = "glium")]
implement_vertex!(Position, position);
#[cfg(feature = "vulkano")]
impl_vertex!(Position, position);

impl<I: FromPrimitive> FromRawVertex<I> for Position {
    fn process(
        vertices: Vec<(f32, f32, f32, f32)>,
        _: Vec<(f32, f32, f32)>,
        _: Vec<(f32, f32, f32)>,
        polygons: Vec<Polygon>,
    ) -> ObjResult<(Vec<Self>, Vec<I>)> {
        let vb = vertices
            .into_iter()
            .map(|v| Position {
                position: [v.0, v.1, v.2],
            })
            .collect();
        let mut ib = Vec::with_capacity(polygons.len() * 3);
        {
            let mut map = |pi: usize| {
                ib.push(I::from_usize(pi).expect("Unable to convert the index from usize"))
            };

            for polygon in polygons {
                match polygon {
                    Polygon::P(ref vec) if vec.len() == 3 => {
                        for &pi in vec {
                            map(pi)
                        }
                    }
                    Polygon::PT(ref vec) | Polygon::PN(ref vec) if vec.len() == 3 => {
                        for &(pi, _) in vec {
                            map(pi)
                        }
                    }
                    Polygon::PTN(ref vec) if vec.len() == 3 => {
                        for &(pi, _, _) in vec {
                            map(pi)
                        }
                    }
                    _ => make_error!(
                        UntriangulatedModel,
                        "Model should be triangulated first to be loaded properly"
                    ),
                }
            }
        }
        Ok((vb, ib))
    }
}

/// Vertex data type of `Obj` which contains position, normal and texture data of a vertex.
#[derive(Copy, PartialEq, Clone, Debug)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "vulkano", derive(Default))]
pub struct TexturedVertex {
    /// Position vector of a vertex.
    pub position: [f32; 3],
    /// Normal vertor of a vertex.
    pub normal: [f32; 3],
    /// Texture of a vertex.
    pub texture: [f32; 3],
}

#[cfg(feature = "glium")]
implement_vertex!(TexturedVertex, position, normal, texture);
#[cfg(feature = "vulkano")]
impl_vertex!(TexturedVertex, position, normal, texture);

impl<I: FromPrimitive + Copy> FromRawVertex<I> for TexturedVertex {
    fn process(
        positions: Vec<(f32, f32, f32, f32)>,
        normals: Vec<(f32, f32, f32)>,
        tex_coords: Vec<(f32, f32, f32)>,
        polygons: Vec<Polygon>,
    ) -> ObjResult<(Vec<Self>, Vec<I>)> {
        let mut vb = Vec::with_capacity(polygons.len() * 3);
        let mut ib = Vec::with_capacity(polygons.len() * 3);
        {
            let mut cache = HashMap::new();
            let mut map = |pi: usize, ni: usize, ti: usize| {
                // Look up cache
                let index = match cache.entry((pi, ni, ti)) {
                    // Cache miss -> make new, store it on cache
                    Entry::Vacant(entry) => {
                        let p = positions[pi];
                        let n = normals[ni];
                        let t = tex_coords[ti];
                        let vertex = TexturedVertex {
                            position: [p.0, p.1, p.2],
                            normal: [n.0, n.1, n.2],
                            texture: [t.0, t.1, t.2],
                        };
                        let index = I::from_usize(vb.len())
                            .expect("Unable to convert the index from usize");
                        vb.push(vertex);
                        entry.insert(index);
                        index
                    }
                    // Cache hit -> use it
                    Entry::Occupied(entry) => *entry.get(),
                };
                ib.push(index)
            };

            for polygon in polygons {
                match polygon {
                    Polygon::P(_) => make_error!(InsufficientData, "Tried to extract normal and texture data which are not contained in the model"),
                    Polygon::PT(_) => make_error!(InsufficientData, "Tried to extract normal data which are not contained in the model"),
                    Polygon::PN(_) => make_error!(InsufficientData, "Tried to extract texture data which are not contained in the model"),
                    Polygon::PTN(ref vec) if vec.len() == 3 => {
                        for &(pi, ti, ni) in vec { map(pi, ni, ti) }
                    }
                    _ => make_error!(UntriangulatedModel, "Model should be triangulated first to be loaded properly")
                }
            }
        }
        vb.shrink_to_fit();
        Ok((vb, ib))
    }
}

#[cfg(feature = "glium")]
mod glium_support {
    use super::Obj;
    use glium::backend::Facade;
    use glium::{index, vertex, IndexBuffer, VertexBuffer};

    impl<V: vertex::Vertex, I: glium::index::Index> Obj<V, I> {
        /// Retrieve glium-compatible vertex buffer from Obj
        pub fn vertex_buffer<F: Facade>(
            &self,
            facade: &F,
        ) -> Result<VertexBuffer<V>, vertex::BufferCreationError> {
            VertexBuffer::new(facade, &self.vertices)
        }

        /// Retrieve glium-compatible index buffer from Obj
        pub fn index_buffer<F: Facade>(
            &self,
            facade: &F,
        ) -> Result<IndexBuffer<I>, index::BufferCreationError> {
            IndexBuffer::new(facade, index::PrimitiveType::TrianglesList, &self.indices)
        }
    }
}