ferrum-wgpu 0.1.0

use std::io::{BufReader, Cursor};
#[cfg(not(target_arch = "wasm32"))]
use std::path::{Path, PathBuf};

use crate::{
    assets::{self, TypeModel},
    renderer,
};
use cgmath::{Vector2, Vector3};
use wgpu::{BindGroup, Buffer, util::DeviceExt};

#[cfg(target_arch = "wasm32")]
fn format_url(file_name: &str) -> reqwest::Url {
    let base = reqwest::Url::parse("https://pub-72c0c8dd15e249a0a448095fb52cc05c.r2.dev/").unwrap();
    base.join(file_name).unwrap()
}

#[cfg(not(target_arch = "wasm32"))]
fn resolve_resource_path(file_name: &str) -> anyhow::Result<PathBuf> {
    let mut candidate_names: Vec<String> = vec![file_name.to_string()];
    if let Some(base_name) = file_name.strip_suffix(".jpg") {
        candidate_names.push(format!("{base_name}.jpeg"));
    } else if let Some(base_name) = file_name.strip_suffix(".jpeg") {
        candidate_names.push(format!("{base_name}.jpg"));
    }

    let mut tried_paths: Vec<PathBuf> = Vec::new();

    // Keep build.rs output as first choice.
    for candidate_name in &candidate_names {
        let out_dir_path: PathBuf = Path::new(env!("OUT_DIR")).join("res").join(candidate_name);
        tried_paths.push(out_dir_path.clone());
        if out_dir_path.is_file() {
            return Ok(out_dir_path);
        }
    }

    // Fallback for local runs from the workspace.
    for candidate_name in &candidate_names {
        let manifest_res_path: PathBuf = Path::new(env!("CARGO_MANIFEST_DIR"))
            .join("res")
            .join(candidate_name);
        tried_paths.push(manifest_res_path.clone());
        if manifest_res_path.is_file() {
            return Ok(manifest_res_path);
        }
    }

    // Fallback for packaged/copy-near-exe runs.
    if let std::result::Result::Ok(exe_path) = std::env::current_exe() {
        if let std::option::Option::Some(exe_dir) = exe_path.parent() {
            for candidate_name in &candidate_names {
                let exe_res_path: PathBuf = exe_dir.join("res").join(candidate_name);
                tried_paths.push(exe_res_path.clone());
                if exe_res_path.is_file() {
                    return Ok(exe_res_path);
                }
            }
        }
    }

    let searched: String = tried_paths
        .iter()
        .map(|p| p.display().to_string())
        .collect::<Vec<_>>()
        .join(" | ");

    anyhow::bail!("No se encontro el recurso '{file_name}'. Rutas probadas: {searched}")
}

pub async fn load_string(file_name: &str) -> anyhow::Result<String> {
    log::debug!("Open: {:?}", file_name);

    #[cfg(target_arch = "wasm32")]
    let text = {
        let url = format_url(file_name);
        log::debug!("[load_string] GET {}", url);
        let resp = reqwest::get(url.clone()).await.map_err(|e| {
            log::error!("[load_string] fetch failed for '{}': {}", url, e);
            e
        })?;
        if !resp.status().is_success() {
            log::error!("[load_string] HTTP {} for '{}'", resp.status(), url);
            anyhow::bail!("HTTP {} fetching '{}'", resp.status(), url);
        }
        resp.text().await?
    };

    #[cfg(not(target_arch = "wasm32"))]
    let text: String = {
        let path: PathBuf = resolve_resource_path(file_name).map_err(|e| {
            log::error!("[load_string] resource not found '{}': {}", file_name, e);
            e
        })?;

        log::debug!("[load_string] resolved '{}' -> {:?}", file_name, path);
        std::fs::read_to_string(path)?
    };

    Ok(text)
}

pub async fn load_binary(file_name: &str) -> anyhow::Result<Vec<u8>> {
    #[cfg(target_arch = "wasm32")]
    let data = {
        let url = format_url(file_name);
        log::debug!("[load_binary] GET {}", url);
        let resp = reqwest::get(url.clone()).await.map_err(|e| {
            log::error!("[load_binary] fetch failed for '{}': {}", url, e);
            e
        })?;
        if !resp.status().is_success() {
            log::error!("[load_binary] HTTP {} for '{}'", resp.status(), url);
            anyhow::bail!("HTTP {} fetching '{}'", resp.status(), url);
        }
        resp.bytes().await?.to_vec()
    };

    #[cfg(not(target_arch = "wasm32"))]
    let data = {
        let path: PathBuf = resolve_resource_path(file_name).map_err(|e| {
            log::error!("[load_binary] resource not found '{}': {}", file_name, e);
            e
        })?;

        std::fs::read(path)?
    };

    Ok(data)
}

pub async fn load_texture(
    file_name: &str,
    device: &wgpu::Device,
    queue: &wgpu::Queue,
    is_normal_map: bool,
) -> anyhow::Result<renderer::Texture> {
    let data: Vec<u8> = load_binary(file_name).await?;
    renderer::Texture::from_bytes(device, queue, &data, file_name, is_normal_map)
}

pub async fn load_model(
    file_name: &str,
    device: &wgpu::Device,
    queue: &wgpu::Queue,
    layout: &wgpu::BindGroupLayout,
    instances: Vec<assets::Instance>,
    type_model: TypeModel,
) -> anyhow::Result<assets::Model> {
    let obj_text: String = load_string(file_name).await?;
    let obj_cursor: Cursor<String> = Cursor::new(obj_text);
    let mut obj_reder: BufReader<_> = BufReader::new(obj_cursor);

    let parent_path: String = std::path::Path::new(file_name)
        .parent()
        .and_then(|p| p.to_str())
        .unwrap_or("")
        .to_string();

    let (models, obj_materials): (
        Vec<tobj::Model>,
        Result<Vec<tobj::Material>, tobj::LoadError>,
    ) = tobj::load_obj_buf_async(
        &mut obj_reder,
        &tobj::LoadOptions {
            triangulate: true,
            single_index: true,
            ..Default::default()
        },
        |mtl_path| {
            let parent_path: String = parent_path.clone();
            async move {
                let full_mtl_path: String = if parent_path.is_empty() {
                    mtl_path.clone()
                } else {
                    std::path::Path::new(&parent_path)
                        .join(&mtl_path)
                        .to_str()
                        .unwrap()
                        .to_string()
                };
                log::debug!("Buscando mtl: {}", full_mtl_path);
                let mat_text: String = load_string(&full_mtl_path).await.unwrap();
                tobj::load_mtl_buf(&mut BufReader::new(Cursor::new(mat_text)))
            }
        },
    )
    .await?;

    let mut materials: Vec<renderer::Material> = Vec::new();
    for m in obj_materials? {
        let full_mtl_path: String = if parent_path.is_empty() {
            m.diffuse_texture.clone()
        } else {
            std::path::Path::new(&parent_path)
                .join(&m.diffuse_texture)
                .to_str()
                .unwrap()
                .to_string()
        };

        let diffuse_texture: renderer::Texture =
            load_texture(&full_mtl_path, device, queue, false).await?;

        let normal_texture: renderer::Texture = if m.normal_texture.is_empty() {
            renderer::Texture::default_normal(device, queue)
        } else {
            let full_normal_path: String = if parent_path.is_empty() {
                m.normal_texture.clone()
            } else {
                std::path::Path::new(&parent_path)
                    .join(&m.normal_texture)
                    .to_str()
                    .unwrap()
                    .to_string()
            };
            load_texture(&full_normal_path, device, queue, true).await?
        };

        let bind_group: BindGroup = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&diffuse_texture.view),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&diffuse_texture.sampler),
                },
                wgpu::BindGroupEntry {
                    binding: 2,
                    resource: wgpu::BindingResource::TextureView(&normal_texture.view),
                },
                wgpu::BindGroupEntry {
                    binding: 3,
                    resource: wgpu::BindingResource::Sampler(&normal_texture.sampler),
                },
            ],
            label: None,
        });

        materials.push(renderer::Material {
            name: m.name,
            diffuse_texture,
            normal_texture,
            bind_group,
        });
    }

    let meshes: Vec<renderer::Mesh> = models
        .into_iter()
        .map(|m| {
            let has_colors: bool = !m.mesh.vertex_color.is_empty();
            let has_normals: bool = !m.mesh.normals.is_empty();
            let has_texcoords: bool = !m.mesh.texcoords.is_empty();
            let has_normal_indices: bool = !m.mesh.normal_indices.is_empty();

            let mut vertices: Vec<assets::ModelVertex> = (0..m.mesh.positions.len() / 3)
                .map(|i| {
                    let pi = i * 3;

                    let position = [
                        m.mesh.positions[pi],
                        m.mesh.positions[pi + 1],
                        m.mesh.positions[pi + 2],
                    ];

                    let text_cords = if has_texcoords {
                        [m.mesh.texcoords[i * 2], 1.0 - m.mesh.texcoords[i * 2 + 1]]
                    } else {
                        [0.0, 0.0]
                    };

                    let normal = if has_normals {
                        let ni = if has_normal_indices {
                            m.mesh.normal_indices[i] as usize * 3
                        } else {
                            pi
                        };
                        [
                            m.mesh.normals[ni],
                            m.mesh.normals[ni + 1],
                            m.mesh.normals[ni + 2],
                        ]
                    } else {
                        [0.0, 0.0, 0.0]
                    };

                    let color = if has_colors {
                        [
                            m.mesh.vertex_color[pi],
                            m.mesh.vertex_color[pi + 1],
                            m.mesh.vertex_color[pi + 2],
                        ]
                    } else {
                        [1.0, 1.0, 1.0]
                    };

                    let tangent: [f32; 3] = [0.0, 0.0, 0.0];

                    let bitangent: [f32; 3] = [0.0, 0.0, 0.0];

                    assets::ModelVertex {
                        position,
                        text_cords,
                        normal,
                        color,
                        tangent,
                        bitangent,
                    }
                })
                .collect::<Vec<_>>();

            let indices: &Vec<u32> = &m.mesh.indices;
            let mut trangles_included = vec![0; vertices.len()];

            for c in indices.chunks(3) {
                let v0: assets::ModelVertex = vertices[c[0] as usize];
                let v1: assets::ModelVertex = vertices[c[1] as usize];
                let v2: assets::ModelVertex = vertices[c[2] as usize];

                let pos0: Vector3<f32> = v0.position.into();
                let pos1: Vector3<f32> = v1.position.into();
                let pos2: Vector3<f32> = v2.position.into();

                let uv0: Vector2<f32> = v0.text_cords.into();
                let uv1: Vector2<f32> = v1.text_cords.into();
                let uv2: Vector2<f32> = v2.text_cords.into();

                // Calculate the edges of the triangle
                let delta_pos1: Vector3<f32> = pos1 - pos0;
                let delta_pos2: Vector3<f32> = pos2 - pos0;

                // This will give us a direction to calculate the
                // tangent and bitangent
                let delta_uv1: Vector2<f32> = uv1 - uv0;
                let delta_uv2: Vector2<f32> = uv2 - uv0;

                // Solving the following system of equations will
                // give us the tangent and bitangent.
                //     delta_pos1 = delta_uv1.x * T + delta_u.y * B
                //     delta_pos2 = delta_uv2.x * T + delta_uv2.y * B

                let r: f32 = 1.0 / (delta_uv1.x * delta_uv2.y - delta_uv1.y * delta_uv2.x);
                let tanget: Vector3<f32> =
                    (delta_pos1 * delta_uv2.y - delta_pos2 * delta_uv1.y) * r;
                let bitanget: Vector3<f32> =
                    (delta_pos2 * delta_uv1.x - delta_pos1 * delta_uv2.x) * -r;

                // Tangent
                vertices[c[0] as usize].tangent =
                    (tanget + Vector3::from(vertices[c[0] as usize].tangent)).into();
                vertices[c[1] as usize].tangent =
                    (tanget + Vector3::from(vertices[c[1] as usize].tangent)).into();
                vertices[c[2] as usize].tangent =
                    (tanget + Vector3::from(vertices[c[2] as usize].tangent)).into();

                // Bitangent
                vertices[c[0] as usize].bitangent =
                    (bitanget + Vector3::from(vertices[c[0] as usize].bitangent)).into();
                vertices[c[1] as usize].bitangent =
                    (bitanget + Vector3::from(vertices[c[1] as usize].bitangent)).into();
                vertices[c[2] as usize].bitangent =
                    (bitanget + Vector3::from(vertices[c[2] as usize].bitangent)).into();

                // Used to average the tangents/bitangents
                trangles_included[c[0] as usize] += 1;
                trangles_included[c[1] as usize] += 1;
                trangles_included[c[2] as usize] += 1;
            }

            // Average the tangents/bitangents
            for (i, n) in trangles_included.into_iter().enumerate() {
                let denom: f32 = 1.0 / n as f32;
                let v: &mut assets::ModelVertex = &mut vertices[i];
                v.tangent = (Vector3::from(v.tangent) * denom).into();
                v.bitangent = (Vector3::from(v.bitangent) * denom).into();
            }

            let vertex_buffer: Buffer =
                device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
                    label: Some(&format!("{:?} Vertex Buffer", file_name)),
                    contents: bytemuck::cast_slice(&vertices),
                    usage: wgpu::BufferUsages::VERTEX,
                });

            let index_buffer: Buffer =
                device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
                    label: Some(&format!("{:?} Index Buffer", file_name)),
                    contents: bytemuck::cast_slice(&m.mesh.indices),
                    usage: wgpu::BufferUsages::INDEX,
                });

            renderer::Mesh {
                name: file_name.to_string(),
                vertex_buffer,
                index_buffer,
                material: m.mesh.material_id.unwrap_or(0),
                indices: m.mesh.indices.len() as u32,
            }
        })
        .collect::<Vec<_>>();

    let instances_raws: Vec<assets::InstanceRaw> = instances.iter().map(|i| i.to_raw()).collect();

    let label: String = format!("{file_name}_instance_buffer");
    let instance_buffer: Buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
        label: Some(&label),
        contents: bytemuck::cast_slice(&instances_raws),
        usage: wgpu::BufferUsages::VERTEX | wgpu::BufferUsages::COPY_DST,
    });

    Ok(assets::Model {
        meshes,
        materials,
        instances,
        instance_buffer,
        type_model,
    })
}