//! Building render pipeline

use super::common::{Vertex, ColoredVertex};

pub fn create_building_pipeline(
    device: &wgpu::Device, 
    format: &wgpu::TextureFormat,
    bind_group_layout: &wgpu::BindGroupLayout
) -> wgpu::RenderPipeline {
    let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
        label: None,
        source: wgpu::ShaderSource::Wgsl(std::borrow::Cow::Borrowed(r#"
            struct CameraUniform {
                params: vec4<f32>,
                theme: vec4<f32>,
            };
            @group(0) @binding(0)
            var<uniform> camera: CameraUniform;

            struct VertexInput {
                @location(0) position: vec2<f32>,
            };

            struct VertexOutput {
                @builtin(position) clip_position: vec4<f32>,
            };

            @vertex
            fn vs_main(
                model: VertexInput,
            ) -> VertexOutput {
                var out: VertexOutput;
                
                let world_pos = model.position;
                
                let x = world_pos.x * camera.params.x + camera.params.z;
                let y = world_pos.y * camera.params.y + camera.params.w;
                
                out.clip_position = vec4<f32>(x, y, 0.0, 1.0);
                return out;
            }

            @fragment
            fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
                // Buildings: Light: #d9d9d9 (0.85), Dark: #333333 (0.2)
                let is_dark = camera.theme.x;
                let color = mix(vec3<f32>(0.92, 0.91, 0.90), vec3<f32>(0.2, 0.2, 0.2), is_dark);
                return vec4<f32>(color, 1.0);
            }
        "#)),
    });

    let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
        label: Some("Building Pipeline Layout"),
        bind_group_layouts: &[bind_group_layout],
        push_constant_ranges: &[],
    });

    device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
        label: None,
        layout: Some(&pipeline_layout),
        vertex: wgpu::VertexState {
            module: &shader,
            entry_point: "vs_main",
            buffers: &[
                Vertex::desc(),
            ],
        },
        fragment: Some(wgpu::FragmentState {
            module: &shader,
            entry_point: "fs_main",
            targets: &[Some(wgpu::ColorTargetState {
                format: *format,
                blend: Some(wgpu::BlendState::REPLACE),
                write_mask: wgpu::ColorWrites::ALL,
            })],
        }),
        primitive: wgpu::PrimitiveState {
            topology: wgpu::PrimitiveTopology::TriangleList,
            strip_index_format: None,
            front_face: wgpu::FrontFace::Ccw,
            cull_mode: None,
            unclipped_depth: false,
            polygon_mode: wgpu::PolygonMode::Fill,
            conservative: false,
        },
        depth_stencil: None,
        multisample: wgpu::MultisampleState {
            count: 4, 
            mask: !0, 
            alpha_to_coverage_enabled: false,
        },
        multiview: None,
    })
}

/// Colored building pipeline - uses per-vertex color for different building types
pub fn create_colored_building_pipeline(
    device: &wgpu::Device, 
    format: &wgpu::TextureFormat,
    bind_group_layout: &wgpu::BindGroupLayout
) -> wgpu::RenderPipeline {
    let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
        label: None,
        source: wgpu::ShaderSource::Wgsl(std::borrow::Cow::Borrowed(r#"
            struct CameraUniform {
                params: vec4<f32>,
                theme: vec4<f32>,
            };
            @group(0) @binding(0)
            var<uniform> camera: CameraUniform;

            struct VertexInput {
                @location(0) position: vec2<f32>,
                @location(1) color: vec3<f32>,  // Per-vertex color (light theme)
            };

            struct VertexOutput {
                @builtin(position) clip_position: vec4<f32>,
                @location(0) v_color: vec3<f32>,
            };

            @vertex
            fn vs_main(model: VertexInput) -> VertexOutput {
                var out: VertexOutput;
                
                let x = model.position.x * camera.params.x + camera.params.z;
                let y = model.position.y * camera.params.y + camera.params.w;
                
                out.clip_position = vec4<f32>(x, y, 0.0, 1.0);
                out.v_color = model.color;
                return out;
            }

            @fragment
            fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
                let is_dark = camera.theme.x;
                // Dark theme: darken the light theme color
                let dark_color = in.v_color * 0.5;
                let color = mix(in.v_color, dark_color, is_dark);
                return vec4<f32>(color, 1.0);
            }
        "#)),
    });

    let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
        label: Some("Colored Building Pipeline Layout"),
        bind_group_layouts: &[bind_group_layout],
        push_constant_ranges: &[],
    });

    device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
        label: Some("Colored Building Pipeline"),
        layout: Some(&pipeline_layout),
        vertex: wgpu::VertexState {
            module: &shader,
            entry_point: "vs_main",
            buffers: &[ColoredVertex::desc()],
        },
        fragment: Some(wgpu::FragmentState {
            module: &shader,
            entry_point: "fs_main",
            targets: &[Some(wgpu::ColorTargetState {
                format: *format,
                blend: Some(wgpu::BlendState::REPLACE),
                write_mask: wgpu::ColorWrites::ALL,
            })],
        }),
        primitive: wgpu::PrimitiveState {
            topology: wgpu::PrimitiveTopology::TriangleList,
            strip_index_format: None,
            front_face: wgpu::FrontFace::Ccw,
            cull_mode: None,
            unclipped_depth: false,
            polygon_mode: wgpu::PolygonMode::Fill,
            conservative: false,
        },
        depth_stencil: None,
        multisample: wgpu::MultisampleState {
            count: 4, 
            mask: !0, 
            alpha_to_coverage_enabled: false,
        },
        multiview: None,
    })
}