collada 0.17.0

use crate::obj::*;
use crate::utils::*;
use std::collections::HashMap;
use std::fs::File;
use std::io::Read;
use std::path::Path;
use std::str::FromStr;
use xml::Element;
use xml::Xml::CharacterNode;

use vecmath;
use xml;

use crate::{
    Animation, BindData, BindDataSet, Joint, JointIndex, Skeleton, VertexWeight,
    ROOT_JOINT_PARENT_INDEX,
};

enum GeometryBindingType {
    Polylist,
    Triangles,
    // TODO types below are not implemented
    // Lines,
    // Linestrips,
    // Polygons,
    // Trifans,
    // Tristrips,
}

impl GeometryBindingType {
    fn name(&self) -> &'static str {
        match *self {
            GeometryBindingType::Polylist => "polylist",
            GeometryBindingType::Triangles => "triangles",
        }
    }
}

///
/// Commonly used shading techniques
/// Holds a description of the textures, samplers, shaders, parameters, and
/// passes necessary for rendering this effect using one method.
///
#[derive(Clone, Debug, PartialEq)]
pub struct PhongEffect {
    pub emission: [f32; 4],
    pub ambient: [f32; 4],
    pub diffuse: Diffuse,
    pub specular: Specular,
    pub shininess: f32,
}

///
/// Can be a plain color or point to a texture in the images library
///
#[derive(Clone, Debug, PartialEq)]
pub enum Diffuse {
    Color([f32; 4]),
    Texture(String),
}

type Specular = Diffuse;

#[derive(Clone, Debug, PartialEq)]
pub struct LambertEffect {
    pub emission: [f32; 4],
    pub diffuse: Diffuse,
    pub index_of_refraction: f32,
}

#[derive(Clone, Debug, PartialEq)]
pub enum MaterialEffect {
    Phong(PhongEffect),
    Lambert(LambertEffect),
}

// TODO: Add more effect types and then unify them under a technique enum.
// Lambert
// Blinn
// Constant
//

pub struct ColladaDocument {
    pub root_element: xml::Element, // TODO figure out how to cache skeletal and skinning data, as we need to
                                    // access them multiple times
}

impl ColladaDocument {
    ///
    /// Construct a ColladaDocument for the XML document at the given path
    ///
    pub fn from_path(path: &Path) -> Result<ColladaDocument, &'static str> {
        let file_result = File::open(path);

        let mut file = match file_result {
            Ok(file) => file,
            Err(_) => return Err("Failed to open COLLADA file at path."),
        };

        let mut xml_string = String::new();
        match file.read_to_string(&mut xml_string) {
            Ok(_) => {}
            Err(_) => return Err("Failed to read COLLADA file."),
        };

        ColladaDocument::from_str(&xml_string)
    }

    ///
    /// Construct a ColladaDocument from an XML string
    ///
    pub fn from_str(xml_string: &str) -> Result<ColladaDocument, &'static str> {
        match xml_string.parse() {
            Ok(root_element) => Ok(ColladaDocument { root_element }),
            Err(_) => Err("Error while parsing COLLADA document."),
        }
    }

    fn get_color(el: &Element) -> Option<[f32; 4]> {
        let v: Vec<f32> = parse_string_to_vector(el.content_str().as_str());
        if v.len() == 4 {
            Some([v[0], v[1], v[2], v[3]])
        } else {
            None
        }
    }

    fn get_lambert(&self, lamb: &Element, ns: Option<&str>) -> LambertEffect {
        let emission_color = lamb
            .get_child("emission", ns)
            .expect("lambert is missing emission")
            .get_child("color", ns)
            .expect("emission is missing color");
        let emission =
            ColladaDocument::get_color(emission_color).expect("could not get emission color.");
        let diffuse_element = lamb
            .get_child("diffuse", ns)
            .expect("lambert is missing diffuse");

        let diffuse_texture = diffuse_element.get_child("texture", ns);

        let diffuse;
        if let Some(texture) = diffuse_texture {
            diffuse = Diffuse::Texture(
                texture
                    .get_attribute("texture", None)
                    .expect("No texture attribute on texture")
                    .to_string(),
            );
        } else {
            let diffuse_element_color = diffuse_element
                .get_child("color", ns)
                .expect("diffuse is missing color");
            let diffuse_color = ColladaDocument::get_color(diffuse_element_color)
                .expect("could not get diffuse color.");
            diffuse = Diffuse::Color(diffuse_color);
        }

        let index_of_refraction: f32 = lamb
            .get_child("index_of_refraction", ns)
            .expect("lambert is missing index_of_refraction")
            .get_child("float", ns)
            .expect("index_of_refraction is missing float")
            .content_str()
            .as_str()
            .parse()
            .ok()
            .expect("could not parse index_of_refraction");

        LambertEffect {
            diffuse,
            emission,
            index_of_refraction,
        }
    }

    fn get_phong(&self, phong: &Element, ns: Option<&str>) -> PhongEffect {
        let emission_color = phong
            .get_child("emission", ns)
            .expect("phong is missing emission")
            .get_child("color", ns)
            .expect("emission is missing color");
        let emission =
            ColladaDocument::get_color(emission_color).expect("could not get emission color.");
        let ambient_color = phong
            .get_child("ambient", ns)
            .expect("phong is missing ambient")
            .get_child("color", ns)
            .expect("ambient is missing color");
        let ambient =
            ColladaDocument::get_color(ambient_color).expect("could not get ambient color.");
        
        let diffuse_element = phong
            .get_child("diffuse", ns)
            .expect("phong is missing diffuse");

        let diffuse_texture = diffuse_element.get_child("texture", ns);

        let diffuse;
        if let Some(texture) = diffuse_texture {
            diffuse = Diffuse::Texture(
                texture
                    .get_attribute("texture", None)
                    .expect("No texture attribute on texture")
                    .to_string(),
            );
        } else {
            let diffuse_element_color = diffuse_element
                .get_child("color", ns)
                .expect("diffuse is missing color");
            let diffuse_color = ColladaDocument::get_color(diffuse_element_color)
                .expect("could not get diffuse color.");
            diffuse = Diffuse::Color(diffuse_color);
        }


    let specular_element = phong
        .get_child("specular", ns)
        .expect("phong is missing specular");

    let specular_texture = specular_element.get_child("texture", ns);

    let specular;
    if let Some(texture) = specular_texture {
        specular = Specular::Texture(
            texture
                .get_attribute("texture", None)
                .expect("No texture attribute on texture")
                .to_string(),
        );
    } else {
        let specular_element_color = specular_element
            .get_child("color", ns)
            .expect("specular is missing color");
        let specular_color = ColladaDocument::get_color(specular_element_color)
            .expect("could not get specular color.");
        specular = Specular::Color(specular_color);
    }

        let shininess: f32 = phong
            .get_child("shininess", ns)
            .expect("phong is missing shininess")
            .get_child("float", ns)
            .expect("shininess is missing float")
            .content_str()
            .as_str()
            .parse()
            .ok()
            .expect("could not parse shininess");
        
        PhongEffect {
            ambient,
            diffuse,
            emission,
            // index_of_refraction,
            shininess,
            specular,
        }
    }

    ///
    /// Returns the library of effects.
    /// Current only supports Phong shading.
    ///
    pub fn get_effect_library(&self) -> HashMap<String, MaterialEffect> {
        let ns = self.get_ns();
        let lib_effs = self
            .root_element
            .get_child("library_effects", ns)
            .expect("Could not get library_effects from the document.");
        lib_effs
            .get_children("effect", ns)
            .flat_map(|el: &Element| -> Option<(String, MaterialEffect)> {
                let id = el
                    .get_attribute("id", None)
                    .unwrap_or_else(|| panic!("effect is missing its id. {:#?}", el));
                let prof = el.get_child("profile_COMMON", ns)?;
                let tech = prof.get_child("technique", ns)?;
                let phong = tech.get_child("phong", ns);
                if let Some(p) = phong {
                    let phong_effect = self.get_phong(p, ns);
                    return Some((id.to_string(), MaterialEffect::Phong(phong_effect)));
                };
                let lambert = tech.get_child("lambert", ns);
                if let Some(lam) = lambert {
                    let lambert_effect = self.get_lambert(lam, ns);
                    return Some((id.to_string(), MaterialEffect::Lambert(lambert_effect)));
                };

                None
            })
            .collect()
    }

    pub fn get_material_to_effect(&self) -> HashMap<String, String> {
        let ns = self.get_ns();
        let lib_mats = self
            .root_element
            .get_child("library_materials", ns)
            .expect("Could not get library_materials from the document");
        lib_mats
            .get_children("material", ns)
            .flat_map(|el| {
                let id = el
                    .get_attribute("id", None)
                    .unwrap_or_else(|| panic!("material is missing its id. {:#?}", el));
                let mut url: String = el
                    .get_child("instance_effect", ns)
                    .expect("could not get material instance_effect")
                    .get_attribute("url", None)
                    .expect("could not get material instance_effect url attribute")
                    .to_string();
                if url.remove(0) == '#' {
                    Some((id.to_string(), url))
                } else {
                    None
                }
            })
            .collect()
    }

    ///
    /// Returns a hashmap of <imageid, filename>
    ///
    pub fn get_images(&self) -> HashMap<String, String> {
        let ns = self.get_ns();
        let lib_images = self
            .root_element
            .get_child("library_images", ns)
            .expect("Could not get library_images from the document");
        lib_images
            .get_children("image", ns)
            .flat_map(|el| {
                let id = el
                    .get_attribute("id", None)
                    .expect(&format!("image is missing its id. {:#?}", el))
                    .to_string();
                let file_name = el
                    .get_child("init_from", ns)
                    .expect("Could not get image from the element")
                    .content_str();
                Some((id, file_name))
            })
            .collect()
    }

    ///
    /// Return a vector of all Animations in the Collada document
    ///
    pub fn get_animations(&self) -> Option<Vec<Animation>> {
        match self
            .root_element
            .get_child("library_animations", self.get_ns())
        {
            Some(library_animations) => {
                let animations = library_animations.get_children("animation", self.get_ns());
                Some(animations.filter_map(|a| self.get_animation(a)).collect())
            }
            None => None,
        }
    }

    ///
    /// Construct an Animation struct for the given <animation> element if possible
    ///
    fn get_animation(&self, animation_element: &Element) -> Option<Animation> {
        let channel_element = animation_element
            .get_child("channel", self.get_ns())
            .expect("Missing channel element in animation element");

        let target = channel_element
            .get_attribute("target", None)
            .expect("Missing target attribute in animation channel element");

        let sampler_element = animation_element
            .get_child("sampler", self.get_ns())
            .expect("Missing sampler element in animation element");

        // Note: Assuming INPUT for animation is 'time'
        let time_input = self
            .get_input(sampler_element, "INPUT")
            .expect("Missing input element for animation INPUT (sample time)");

        let sample_times = self
            .get_array_for_input(animation_element, time_input)
            .expect("Missing / invalid source for animation INPUT");

        // Note: Assuming OUTPUT for animation is a pose matrix
        let pose_input = self
            .get_input(sampler_element, "OUTPUT")
            .expect("Missing input element for animation OUTPUT (pose transform)");

        let sample_poses_flat = self
            .get_array_for_input(animation_element, pose_input)
            .expect("Missing / invalid source for animation OUTPUT");

        // Convert flat array of floats into array of matrices
        let sample_poses = to_matrix_array(sample_poses_flat);

        Some(Animation {
            target: target.to_string(),
            sample_times,
            sample_poses,
        })
    }

    ///
    /// Populate and return an ObjSet for the meshes in the Collada document
    ///
    pub fn get_obj_set(&self) -> Option<ObjSet> {
        let library_geometries = (self
            .root_element
            .get_child("library_geometries", self.get_ns()))?;
        let geometries = library_geometries.get_children("geometry", self.get_ns());
        let objects = geometries.filter_map(|g| self.get_object(g)).collect();

        Some(ObjSet {
            material_library: None,
            objects,
        })
    }

    ///
    /// Populate and return a BindDataSet from the Collada document
    ///
    pub fn get_bind_data_set(&self) -> Option<BindDataSet> {
        let library_controllers = (self
            .root_element
            .get_child("library_controllers", self.get_ns()))?;
        let controllers = library_controllers.get_children("controller", self.get_ns());
        let bind_data = controllers.filter_map(|c| self.get_bind_data(c)).collect();
        Some(BindDataSet { bind_data })
    }

    ///
    ///
    ///
    pub fn get_skeletons(&self) -> Option<Vec<Skeleton>> {
        let library_visual_scenes = (self
            .root_element
            .get_child("library_visual_scenes", self.get_ns()))?;
        let visual_scene = (library_visual_scenes.get_child("visual_scene", self.get_ns()))?;

        let bind_data_set = (self.get_bind_data_set())?;

        let skeleton_ids: Vec<&str> = pre_order_iter(visual_scene)
            .filter(|e| e.name == "skeleton")
            .filter_map(|s| {
                if let CharacterNode(ref id) = s.children[0] {
                    Some(&id[..])
                } else {
                    None
                }
            })
            .map(|id| id.trim_start_matches('#'))
            .collect();

        if skeleton_ids.is_empty() {
            return None;
        }

        let skeletons = pre_order_iter(visual_scene)
            .filter(|e| e.name == "node")
            .filter(|e| has_attribute_with_value(e, "id", skeleton_ids[0]))
            .filter_map(|e| self.get_skeleton(e, &bind_data_set.bind_data[0]))
            .collect();

        Some(skeletons)
    }

    fn get_skeleton(&self, root_element: &Element, bind_data: &BindData) -> Option<Skeleton> {
        let mut parent_index_stack: Vec<JointIndex> = vec![ROOT_JOINT_PARENT_INDEX];
        let mut joints = Vec::new();
        let mut bind_poses = Vec::new();
        for (joint_index, (joint_element, depth)) in pre_order_with_depth_iter(root_element)
            .filter(|&(e, _)| e.name == "node" && has_attribute_with_value(e, "type", "JOINT"))
            .enumerate()
        {
            // If our depth decreases after visiting a leaf node, pop indices off the stack
            // until it matches our depth
            while depth < parent_index_stack.len() - 1 {
                parent_index_stack.pop();
            }

            let joint_name = joint_element.get_attribute("id", None).unwrap().to_string();

            let mut joint_names_with_bind_pose = bind_data
                .joint_names
                .iter()
                .zip(bind_data.inverse_bind_poses.iter());
            let inverse_bind_pose =
                match joint_names_with_bind_pose.find(|&(name, _)| *name == joint_name) {
                    Some((_, pose)) => *pose,
                    _ => vecmath::mat4_id(),
                };

            joints.push(Joint {
                inverse_bind_pose,
                name: joint_name,
                parent_index: *parent_index_stack.last().unwrap(),
            });

            let pose_matrix_element = (joint_element.get_child("matrix", self.get_ns()))?;
            let pose_matrix_array = (get_array_content(pose_matrix_element))?;
            let mut pose_matrix = vecmath::mat4_id();
            for (&array_value, matrix_value) in pose_matrix_array
                .iter()
                .zip(pose_matrix.iter_mut().flat_map(|n| n.iter_mut()))
            {
                *matrix_value = array_value;
            }

            bind_poses.push(pose_matrix);

            parent_index_stack.push(joint_index as JointIndex);
        }

        Some(Skeleton { joints, bind_poses })
    }

    fn get_bind_data(&self, controller_element: &xml::Element) -> Option<BindData> {
        let skeleton_name = controller_element.get_attribute("name", None);
        let skin_element = controller_element.get_child("skin", self.get_ns())?;
        let object_name = skin_element
            .get_attribute("source", None)?
            .trim_start_matches('#');

        let vertex_weights_element = (skin_element.get_child("vertex_weights", self.get_ns()))?;
        let vertex_weights = (self.get_vertex_weights(vertex_weights_element))?;

        let joints_element = (skin_element.get_child("joints", self.get_ns()))?;

        let joint_input = (self.get_input(joints_element, "JOINT"))?;
        let joint_names = (self.get_array_for_input(skin_element, joint_input))?;

        let weights_input = (self.get_input(vertex_weights_element, "WEIGHT"))?;
        let weights = (self.get_array_for_input(skin_element, weights_input))?;

        let inv_bind_matrix_input = (self.get_input(joints_element, "INV_BIND_MATRIX"))?;

        let inverse_bind_poses =
            to_matrix_array((self.get_array_for_input(skin_element, inv_bind_matrix_input))?);

        Some(BindData {
            object_name: object_name.to_string(),
            skeleton_name: skeleton_name.map(|s| s.to_string()),
            joint_names,
            inverse_bind_poses,
            weights,
            vertex_weights,
        })
    }

    fn get_vertex_weights(
        &self,
        vertex_weights_element: &xml::Element,
    ) -> Option<Vec<VertexWeight>> {
        let joint_index_offset = (self.get_input_offset(vertex_weights_element, "JOINT"))?;
        let weight_index_offset = (self.get_input_offset(vertex_weights_element, "WEIGHT"))?;

        let vcount_element = (vertex_weights_element.get_child("vcount", self.get_ns()))?;
        let weights_per_vertex: Vec<usize> = (get_array_content(vcount_element))?;
        let input_count = vertex_weights_element
            .get_children("input", self.get_ns())
            .count();

        let v_element = (vertex_weights_element.get_child("v", self.get_ns()))?;
        let joint_weight_indices: Vec<usize> = (get_array_content(v_element))?;
        let mut joint_weight_iter = joint_weight_indices.chunks(input_count);

        let mut vertex_indices: Vec<usize> = Vec::new();
        for (index, n) in weights_per_vertex.iter().enumerate() {
            for _ in 0..*n {
                vertex_indices.push(index);
            }
        }

        let vertex_weights = vertex_indices
            .iter()
            .filter_map(|vertex_index| {
                joint_weight_iter.next().map(|joint_weight| VertexWeight {
                    vertex: *vertex_index,
                    joint: joint_weight[joint_index_offset] as JointIndex,
                    weight: joint_weight[weight_index_offset],
                })
            })
            .collect();

        Some(vertex_weights)
    }

    fn get_object(&self, geometry_element: &xml::Element) -> Option<Object> {
        let id = (geometry_element.get_attribute("id", None))?;
        let name = (geometry_element.get_attribute("name", None))?;
        let mesh_element = (geometry_element.get_child("mesh", self.get_ns()))?;
        let mesh = (self.get_mesh_elements(mesh_element))?;

        let mut first_primitive_element = None;
        'find_primitive: for t in [
            GeometryBindingType::Polylist,
            GeometryBindingType::Triangles,
        ]
        .iter()
        {
            first_primitive_element = mesh_element.get_child(t.name(), self.get_ns());
            if first_primitive_element.is_some() {
                break 'find_primitive;
            }
        }
        let first_primitive_element = first_primitive_element?;

        let positions_input = (self.get_input(first_primitive_element, "VERTEX"))?;
        let positions_array = (self.get_array_for_input(mesh_element, positions_input))?;
        let positions: Vec<_> = positions_array
            .chunks(3)
            .map(|coords| Vertex {
                x: coords[0],
                y: coords[1],
                z: coords[2],
            })
            .collect();

        let normals = {
            match self.get_input(first_primitive_element, "NORMAL") {
                Some(normals_input) => {
                    let normals_array = (self.get_array_for_input(mesh_element, normals_input))?;
                    normals_array
                        .chunks(3)
                        .map(|coords| Normal {
                            x: coords[0],
                            y: coords[1],
                            z: coords[2],
                        })
                        .collect()
                }
                None => Vec::new(),
            }
        };

        let texcoords = {
            match self.get_input(first_primitive_element, "TEXCOORD") {
                Some(texcoords_input) => {
                    let texcoords_array =
                        (self.get_array_for_input(mesh_element, texcoords_input))?;
                    texcoords_array
                        .chunks(2)
                        .map(|coords| TVertex {
                            x: coords[0],
                            y: coords[1],
                        })
                        .collect()
                }
                None => Vec::new(),
            }
        };

        // TODO cache! also only if any skeleton

        let joint_weights = match self.get_skeletons() {
            Some(skeletons) => {
                let skeleton = &skeletons[0];
                // TODO cache bind_data_set
                let bind_data_set = (self.get_bind_data_set())?;
                let bind_data_opt = bind_data_set
                    .bind_data
                    .iter()
                    .find(|bind_data| bind_data.object_name == id);

                if let Some(bind_data) = bind_data_opt {
                    // Build an array of joint weights for each vertex
                    // Initialize joint weights array with no weights for any vertex
                    let mut joint_weights = vec![
                        JointWeights {
                            joints: [0; 4],
                            weights: [0.0; 4]
                        };
                        positions.len()
                    ];

                    for vertex_weight in bind_data.vertex_weights.iter() {
                        let joint_name = &bind_data.joint_names[vertex_weight.joint as usize];
                        let vertex_joint_weights: &mut JointWeights =
                            &mut joint_weights[vertex_weight.vertex];

                        if let Some((next_index, _)) = vertex_joint_weights
                            .weights
                            .iter()
                            .enumerate()
                            .find(|&(_, weight)| *weight == 0.0)
                        {
                            if let Some((joint_index, _)) = skeleton
                                .joints
                                .iter()
                                .enumerate()
                                .find(|&(_, j)| &j.name == joint_name)
                            {
                                vertex_joint_weights.joints[next_index] = joint_index;
                                vertex_joint_weights.weights[next_index] =
                                    bind_data.weights[vertex_weight.weight];
                            } else {
                                error!("Couldn't find joint: {}", joint_name);
                            }
                        } else {
                            error!("Too many joint influences for vertex");
                        }
                    }
                    joint_weights
                } else {
                    Vec::new()
                }
            }
            None => Vec::new(),
        };

        Some(Object {
            id: id.to_string(),
            name: name.to_string(),
            vertices: positions,
            tex_vertices: texcoords,
            normals,
            joint_weights,
            geometry: vec![Geometry {
                smooth_shading_group: 0,
                mesh,
            }],
        })
    }

    fn get_ns(&self) -> Option<&str> {
        match self.root_element.ns {
            Some(ref ns) => Some(&ns[..]),
            None => None,
        }
    }

    fn get_input_offset(&self, parent_element: &xml::Element, semantic: &str) -> Option<usize> {
        let mut inputs = parent_element.get_children("input", self.get_ns());
        let input: &Element = inputs.find(|i| {
            if let Some(s) = i.get_attribute("semantic", None) {
                s == semantic
            } else {
                false
            }
        })?;
        input
            .get_attribute("offset", None)
            .expect("input is missing offest")
            .parse::<usize>()
            .ok()
    }

    ///
    fn get_input<'a>(&'a self, parent: &'a Element, semantic: &str) -> Option<&'a Element> {
        let mut inputs = parent.get_children("input", self.get_ns());
        match inputs.find(|i| {
            if let Some(s) = i.get_attribute("semantic", None) {
                s == semantic
            } else {
                false
            }
        }) {
            Some(e) => Some(e),
            None => None,
        }
    }

    fn get_input_source<'a>(
        &'a self,
        parent_element: &'a xml::Element,
        input_element: &'a xml::Element,
    ) -> Option<&'a xml::Element> {
        let source_id = (input_element.get_attribute("source", None))?;

        if let Some(element) = parent_element
            .children
            .iter()
            .filter_map(|node| {
                if let xml::Xml::ElementNode(ref e) = node {
                    Some(e)
                } else {
                    None
                }
            })
            .find(|e| {
                if let Some(id) = e.get_attribute("id", None) {
                    let id = "#".to_string() + id;
                    id == source_id
                } else {
                    false
                }
            })
        {
            if element.name == "source" {
                return Some(element);
            } else {
                let input = (element.get_child("input", self.get_ns()))?;
                return self.get_input_source(parent_element, input);
            }
        }
        None
    }

    fn get_array_for_input<T: FromStr>(&self, parent: &Element, input: &Element) -> Option<Vec<T>> {
        let source = (self.get_input_source(parent, input))?;
        let array_element =
            (if let Some(float_array) = source.get_child("float_array", self.get_ns()) {
                Some(float_array)
            } else {
                source.get_child("Name_array", self.get_ns())
            })?;
        get_array_content(array_element)
    }

    fn get_vertex_indices(&self, prim_element: &xml::Element) -> Option<Vec<VertexIndex>> {
        let p_element = (prim_element.get_child("p", self.get_ns()))?;
        let indices: Vec<usize> = (get_array_content(p_element))?;

        let input_count = prim_element
            .get_children("input", self.get_ns())
            .filter(|c| {
                if let Some(set) = c.get_attribute("set", None) {
                    set == "0"
                } else {
                    true
                }
            })
            .count();

        let vertex_offset = (self.get_input_offset(prim_element, "VERTEX"))?;
        let vertex_indices = indices
            .chunks(input_count)
            .map(|indices| indices[vertex_offset])
            .collect();

        Some(vertex_indices)
    }

    fn get_normal_indices(&self, prim_element: &xml::Element) -> Option<Vec<NormalIndex>> {
        let p_element = (prim_element.get_child("p", self.get_ns()))?;
        let indices: Vec<usize> = (get_array_content(p_element))?;

        let input_count = prim_element
            .get_children("input", self.get_ns())
            .filter(|c| {
                if let Some(set) = c.get_attribute("set", None) {
                    set == "0"
                } else {
                    true
                }
            })
            .count();

        self.get_input_offset(prim_element, "NORMAL")
            .map(|normal_offset| {
                indices
                    .chunks(input_count)
                    .map(|indices| indices[normal_offset])
                    .collect()
            })
    }

    fn get_texcoord_indices(&self, prim_element: &xml::Element) -> Option<Vec<TextureIndex>> {
        let p_element = (prim_element.get_child("p", self.get_ns()))?;
        let indices: Vec<usize> = (get_array_content(p_element))?;

        let input_count = prim_element
            .get_children("input", self.get_ns())
            .filter(|c| {
                if let Some(set) = c.get_attribute("set", None) {
                    set == "0"
                } else {
                    true
                }
            })
            .count();

        self.get_input_offset(prim_element, "TEXCOORD")
            .map(|texcoord_offset| {
                indices
                    .chunks(input_count)
                    .map(|indices| indices[texcoord_offset])
                    .collect()
            })
    }

    fn get_vtn_indices(&self, prim_element: &xml::Element) -> Option<Vec<VTNIndex>> {
        let p_element = (prim_element.get_child("p", self.get_ns()))?;
        let indices: Vec<usize> = (get_array_content(p_element))?;

        let input_count = prim_element
            .get_children("input", self.get_ns())
            .filter(|c| {
                if let Some(set) = c.get_attribute("set", None) {
                    set == "0"
                } else {
                    true
                }
            })
            .count();

        let position_offset = (self.get_input_offset(prim_element, "VERTEX"))?;

        let normal_offset_opt = self.get_input_offset(prim_element, "NORMAL");
        let texcoord_offset_opt = self.get_input_offset(prim_element, "TEXCOORD");

        let vtn_indices: Vec<VTNIndex> = indices
            .chunks(input_count)
            .map(|indices| {
                let position_index = indices[position_offset];

                let normal_index_opt =
                    normal_offset_opt.map(|normal_offset| indices[normal_offset]);

                let texcoord_index_opt =
                    texcoord_offset_opt.map(|texcoord_offset| indices[texcoord_offset]);

                (position_index, texcoord_index_opt, normal_index_opt)
            })
            .collect();

        Some(vtn_indices)
    }

    fn get_material(&self, primitive_el: &xml::Element) -> Option<String> {
        primitive_el
            .get_attribute("material", None)
            .map(|s| s.to_string())
    }

    fn get_mesh_elements(&self, mesh_element: &xml::Element) -> Option<Vec<PrimitiveElement>> {
        let mut prims = vec![];
        for child in &mesh_element.children {
            match child {
                xml::Xml::ElementNode(el) => {
                    if el.name == GeometryBindingType::Polylist.name() {
                        let shapes = self
                            .get_polylist_shape(el)
                            .expect("Polylist had no shapes.");
                        let material = self.get_material(el);
                        let polylist = Polylist { shapes, material };
                        prims.push(PrimitiveElement::Polylist(polylist))
                    } else if el.name == GeometryBindingType::Triangles.name() {
                        let material = self.get_material(el);
                        let triangles = self
                            .get_triangles(el, material)
                            .expect("Triangles had no indices.");
                        prims.push(PrimitiveElement::Triangles(triangles))
                    }
                }
                _ => {}
            }
        }

        if prims.is_empty() {
            None
        } else {
            Some(prims)
        }
    }

    fn get_triangles(
        &self,
        triangles: &xml::Element,
        material: Option<String>,
    ) -> Option<Triangles> {
        let count_str: &str = triangles.get_attribute("count", None)?;
        let count = count_str.parse::<usize>().ok().unwrap();

        let vertices = self.get_vertex_indices(triangles).map(|vertex_indices| {
            let mut vertex_iter = vertex_indices.iter();
            (0..count)
                .map(|_| {
                    (
                        *vertex_iter.next().unwrap(),
                        *vertex_iter.next().unwrap(),
                        *vertex_iter.next().unwrap(),
                    )
                })
                .collect()
        })?;

        let tex_vertices = self
            .get_texcoord_indices(triangles)
            .map(|texcoord_indices| {
                let mut texcoord_iter = texcoord_indices.iter();
                (0..count)
                    .map(|_| {
                        (
                            *texcoord_iter.next().unwrap(),
                            *texcoord_iter.next().unwrap(),
                            *texcoord_iter.next().unwrap(),
                        )
                    })
                    .collect()
            });

        let normals = self.get_normal_indices(triangles).map(|normal_indices| {
            let mut normal_iter = normal_indices.iter();
            (0..count)
                .map(|_| {
                    (
                        *normal_iter.next().unwrap(),
                        *normal_iter.next().unwrap(),
                        *normal_iter.next().unwrap(),
                    )
                })
                .collect()
        });

        Some(Triangles {
            vertices,
            tex_vertices,
            normals,
            material,
        })
    }

    fn get_polylist_shape(&self, polylist_element: &xml::Element) -> Option<Vec<Shape>> {
        let vtn_indices = (self.get_vtn_indices(polylist_element))?;

        let vcount_element = (polylist_element.get_child("vcount", self.get_ns()))?;
        let vertex_counts: Vec<usize> = (get_array_content(vcount_element))?;

        let mut vtn_iter = vtn_indices.iter();
        let shapes = vertex_counts
            .iter()
            .map(|vertex_count| {
                match *vertex_count {
                    1 => Shape::Point(*vtn_iter.next().unwrap()),
                    2 => Shape::Line(*vtn_iter.next().unwrap(), *vtn_iter.next().unwrap()),
                    3 => Shape::Triangle(
                        *vtn_iter.next().unwrap(),
                        *vtn_iter.next().unwrap(),
                        *vtn_iter.next().unwrap(),
                    ),
                    n => {
                        // Polys with more than 3 vertices not supported - try to advance and continue
                        // TODO attempt to triangle-fy? (take a look at wavefront_obj)
                        for _ in 0..n {
                            vtn_iter.next();
                        }
                        Shape::Point((0, None, None))
                    }
                }
            })
            .collect();

        Some(shapes)
    }
}

#[test]
fn test_get_obj_set() {
    let collada_document = ColladaDocument::from_path(Path::new("test_assets/test.dae")).unwrap();
    let obj_set = collada_document.get_obj_set().unwrap();
    assert_eq!(obj_set.objects.len(), 1);

    let object = &obj_set.objects[0];
    assert_eq!(object.id, "BoxyWorm-mesh");
    assert_eq!(object.name, "BoxyWorm");
    assert_eq!(object.vertices.len(), 16);
    assert_eq!(object.tex_vertices.len(), 84);
    assert_eq!(object.normals.len(), 28);
    assert_eq!(object.geometry.len(), 1);

    let geometry = &object.geometry[0];

    let prim = &geometry.mesh[0];
    if let PrimitiveElement::Polylist(polylist) = prim {
        assert_eq!(polylist.shapes.len(), 28);
        let shape = polylist.shapes[1];
        if let Shape::Triangle((position_index, Some(texture_index), Some(normal_index)), _, _) =
            shape
        {
            assert_eq!(position_index, 7);
            assert_eq!(texture_index, 3);
            assert_eq!(normal_index, 1);
        } else {
            assert!(false);
        }
    }
}

#[test]
fn test_get_obj_set_triangles_geometry() {
    let collada_document =
        ColladaDocument::from_path(Path::new("test_assets/test_cube_triangles_geometry.dae"))
            .unwrap();
    let obj_set = collada_document.get_obj_set().unwrap();
    assert_eq!(obj_set.objects.len(), 1);

    let object = &obj_set.objects[0];
    assert_eq!(object.id, "Cube-mesh");
    assert_eq!(object.name, "Cube");
    assert_eq!(object.vertices.len(), 8);
    assert_eq!(object.normals.len(), 12);
    assert_eq!(object.geometry.len(), 1);

    let geometry = &object.geometry[0];

    let prim = &geometry.mesh[0];
    match prim {
        PrimitiveElement::Triangles(triangles) => {
            assert_eq!(triangles.vertices.len(), 12);

            let position_index = triangles.vertices[1].0;
            assert_eq!(position_index, 7);

            if let Some(ref normals) = triangles.normals {
                assert_eq!(normals.len(), 12);

                let normal_index = normals[1].0;
                assert_eq!(normal_index, 1);
            } else {
                assert!(false, "Triangle is missing a normal.");
            }
        }
        x => {
            assert!(false, "Not a polylist: {:#?}", x);
        }
    }
}

#[test]
fn test_get_bind_data_set() {
    let collada_document = ColladaDocument::from_path(Path::new("test_assets/test.dae")).unwrap();
    let bind_data_set = collada_document.get_bind_data_set().unwrap();
    let bind_data = &bind_data_set.bind_data[0];

    assert_eq!(bind_data.object_name, "BoxyWorm-mesh");
    assert!(bind_data.skeleton_name.is_some());
    assert_eq!(bind_data.skeleton_name.as_ref().unwrap(), "BoxWormRoot");
    assert_eq!(bind_data.joint_names, ["Root", "UpperArm", "LowerArm"]);
    assert_eq!(bind_data.vertex_weights.len(), 29);
    assert_eq!(bind_data.weights.len(), 29);
    assert_eq!(bind_data.inverse_bind_poses.len(), 3);
}

#[test]
fn test_get_skeletons() {
    let collada_document = ColladaDocument::from_path(Path::new("test_assets/test.dae")).unwrap();
    let skeletons = collada_document.get_skeletons().unwrap();
    assert_eq!(skeletons.len(), 1);

    let skeleton = &skeletons[0];
    assert_eq!(skeleton.joints.len(), 4);
    assert_eq!(skeleton.bind_poses.len(), 4);

    assert_eq!(skeleton.joints[0].name, "Root");
    assert_eq!(skeleton.joints[0].parent_index, ROOT_JOINT_PARENT_INDEX);
    assert!(skeleton.joints[0].inverse_bind_pose != vecmath::mat4_id());

    assert_eq!(skeleton.joints[1].name, "UpperArm");
    assert_eq!(skeleton.joints[1].parent_index, 0);
    assert!(skeleton.joints[1].inverse_bind_pose != vecmath::mat4_id());

    assert_eq!(skeleton.joints[2].name, "UpperArmDanglyBit");
    assert_eq!(skeleton.joints[2].parent_index, 1);
    assert_eq!(skeleton.joints[2].inverse_bind_pose, vecmath::mat4_id());

    assert_eq!(skeleton.joints[3].name, "LowerArm");
    assert_eq!(skeleton.joints[3].parent_index, 0);
    assert!(skeleton.joints[3].inverse_bind_pose != vecmath::mat4_id());
}

#[test]
fn test_get_animations() {
    let collada_document = ColladaDocument::from_path(Path::new("test_assets/test.dae")).unwrap();
    let animations = collada_document.get_animations().unwrap();
    assert_eq!(animations.len(), 4);

    let animation = &animations[1];
    assert_eq!(animation.target, "UpperArm/transform");
    assert_eq!(animation.sample_times.len(), 4);
    assert_eq!(animation.sample_poses.len(), 4);

    let animation = &animations[3];
    assert_eq!(animation.target, "LowerArm/transform");
    assert_eq!(animation.sample_times.len(), 4);
    assert_eq!(animation.sample_poses.len(), 4);
}

#[test]
fn test_get_obj_set_noskeleton() {
    let collada_document =
        ColladaDocument::from_path(Path::new("test_assets/test_noskeleton.dae")).unwrap();
    collada_document.get_obj_set().unwrap();
}