#pragma once

#include <mbgl/shaders/fill_extrusion_layer_ubo.hpp>
#include <mbgl/shaders/shader_source.hpp>
#include <mbgl/shaders/mtl/common.hpp>
#include <mbgl/shaders/mtl/shader_program.hpp>

namespace mbgl {
namespace shaders {

template <>
struct ShaderSource<BuiltIn::FillExtrusionPatternShader, gfx::Backend::Type::Metal> {
    static constexpr auto name = "FillExtrusionPatternShader";
    static constexpr auto vertexMainFunction = "vertexMain";
    static constexpr auto fragmentMainFunction = "fragmentMain";

    static const std::array<UniformBlockInfo, 5> uniforms;
    static const std::array<AttributeInfo, 6> attributes;
    static constexpr std::array<AttributeInfo, 0> instanceAttributes{};
    static const std::array<TextureInfo, 1> textures;

    static constexpr auto source = R"(
struct VertexStage {
    short2 pos [[attribute(5)]];
    short4 normal_ed [[attribute(6)]];

#if !defined(HAS_UNIFORM_u_base)
    float base [[attribute(7)]];
#endif
#if !defined(HAS_UNIFORM_u_height)
    float height [[attribute(8)]];
#endif
#if !defined(HAS_UNIFORM_u_pattern_from)
    ushort4 pattern_from [[attribute(9)]];
#endif
#if !defined(HAS_UNIFORM_u_pattern_to)
    ushort4 pattern_to [[attribute(10)]];
#endif
};

struct FragmentStage {
    float4 position [[position, invariant]];
    float4 lighting;
    float2 pos_a;
    float2 pos_b;

#if !defined(HAS_UNIFORM_u_pattern_from)
    half4 pattern_from;
#endif
#if !defined(HAS_UNIFORM_u_pattern_to)
    half4 pattern_to;
#endif
};

struct FragmentOutput {
    half4 color [[color(0)]];
    //float depth [[depth(less)]]; // Write depth value if it's less than what's already there
};

FragmentStage vertex vertexMain(thread const VertexStage vertx [[stage_in]],
                                device const GlobalPaintParamsUBO& paintParams [[buffer(0)]],
                                device const FillExtrusionDrawableUBO& drawable [[buffer(1)]],
                                device const FillExtrusionTilePropsUBO& tileProps [[buffer(2)]],
                                device const FillExtrusionInterpolateUBO& interp [[buffer(3)]],
                                device const FillExtrusionPropsUBO& props [[buffer(4)]]) {

#if defined(HAS_UNIFORM_u_base)
    const auto base   = props.light_position_base.w;
#else
    const auto base   = max(unpack_mix_float(vertx.base, interp.base_t), 0.0);
#endif
#if defined(HAS_UNIFORM_u_height)
    const auto height = props.height;
#else
    const auto height = max(unpack_mix_float(vertx.height, interp.height_t), 0.0);
#endif

    const float3 normal = float3(vertx.normal_ed.xyz);
    const float edgedistance = vertx.normal_ed.w;
    const float t = glMod(normal.x, 2.0);
    const float z = (t != 0.0) ? height : base;     // TODO: This would come out wrong on GL for negative values, check it...
    const float4 position = drawable.matrix * float4(float2(vertx.pos), z, 1);

#if defined(OVERDRAW_INSPECTOR)
    return {
        .position       = position,
        .lighting       = float4(1.0),
        .pattern_from   = float4(1.0),
        .pattern_to     = float4(1.0),
        .pos_a          = float2(1.0),
        .pos_b          = float2(1.0),
    };
#endif

#if defined(HAS_UNIFORM_u_pattern_from)
    const auto pattern_from = tileProps.pattern_from;
#else
    const auto pattern_from = float4(vertx.pattern_from);
#endif
#if defined(HAS_UNIFORM_u_pattern_to)
    const auto pattern_to   = tileProps.pattern_to;
#else
    const auto pattern_to   = float4(vertx.pattern_to);
#endif

    const float2 pattern_tl_a = pattern_from.xy;
    const float2 pattern_br_a = pattern_from.zw;
    const float2 pattern_tl_b = pattern_to.xy;
    const float2 pattern_br_b = pattern_to.zw;

    const float pixelRatio = paintParams.pixel_ratio;
    const float tileZoomRatio = drawable.tile_ratio;
    const float fromScale = props.from_scale;
    const float toScale = props.to_scale;

    const float2 display_size_a = float2((pattern_br_a.x - pattern_tl_a.x) / pixelRatio, (pattern_br_a.y - pattern_tl_a.y) / pixelRatio);
    const float2 display_size_b = float2((pattern_br_b.x - pattern_tl_b.x) / pixelRatio, (pattern_br_b.y - pattern_tl_b.y) / pixelRatio);

    const float2 pos = normal.x == 1.0 && normal.y == 0.0 && normal.z == 16384.0
        ? float2(vertx.pos) // extrusion top
        : float2(edgedistance, z * drawable.height_factor); // extrusion side
    
    float4 lighting = float4(0.0, 0.0, 0.0, 1.0);
    float directional = clamp(dot(normal / 16383.0, props.light_position_base.xyz), 0.0, 1.0);
    directional = mix((1.0 - props.light_intensity), max((0.5 + props.light_intensity), 1.0), directional);

    if (normal.y != 0.0) {
        // This avoids another branching statement, but multiplies by a constant of 0.84 if no vertical gradient,
        // and otherwise calculates the gradient based on base + height
        directional *= (
            (1.0 - props.vertical_gradient) +
            (props.vertical_gradient * clamp((t + base) * pow(height / 150.0, 0.5), mix(0.7, 0.98, 1.0 - props.light_intensity), 1.0)));
    }

    lighting.rgb += clamp(directional * props.light_color_pad.rgb, mix(float3(0.0), float3(0.3), 1.0 - props.light_color_pad.rgb), float3(1.0));
    lighting *= props.opacity;
    
    return {
        .position       = position,
        .lighting       = lighting,
#if !defined(HAS_UNIFORM_u_pattern_from)
        .pattern_from   = half4(pattern_from),
#endif
#if !defined(HAS_UNIFORM_u_pattern_from)
        .pattern_to     = half4(pattern_to),
#endif
        .pos_a          = get_pattern_pos(drawable.pixel_coord_upper, drawable.pixel_coord_lower, fromScale * display_size_a, tileZoomRatio, pos),
        .pos_b          = get_pattern_pos(drawable.pixel_coord_upper, drawable.pixel_coord_lower, toScale * display_size_b, tileZoomRatio, pos),
    };
}

fragment FragmentOutput fragmentMain(FragmentStage in [[stage_in]],
                                    device const FillExtrusionDrawableUBO& drawable [[buffer(1)]],
                                    device const FillExtrusionTilePropsUBO& tileProps [[buffer(2)]],
                                    device const FillExtrusionPropsUBO& props [[buffer(4)]],
                                    texture2d<float, access::sample> image0 [[texture(0)]],
                                    sampler image0_sampler [[sampler(0)]]) {
#if defined(OVERDRAW_INSPECTOR)
    return {half4(1.0)/*, in.position.z*/};
#endif

#if defined(HAS_UNIFORM_u_pattern_from)
    const auto pattern_from = float4(tileProps.pattern_from);
#else
    const auto pattern_from = float4(in.pattern_from);
#endif
#if defined(HAS_UNIFORM_u_pattern_to)
    const auto pattern_to = float4(tileProps.pattern_to);
#else
    const auto pattern_to = float4(in.pattern_to);
#endif

    const float2 pattern_tl_a = pattern_from.xy;
    const float2 pattern_br_a = pattern_from.zw;
    const float2 pattern_tl_b = pattern_to.xy;
    const float2 pattern_br_b = pattern_to.zw;

    const float2 imagecoord = glMod(in.pos_a, 1.0);
    const float2 pos = mix(pattern_tl_a / drawable.texsize, pattern_br_a / drawable.texsize, imagecoord);
    const float4 color1 = image0.sample(image0_sampler, pos);

    const float2 imagecoord_b = glMod(in.pos_b, 1.0);
    const float2 pos2 = mix(pattern_tl_b / drawable.texsize, pattern_br_b / drawable.texsize, imagecoord_b);
    const float4 color2 = image0.sample(image0_sampler, pos2);

    return {half4(mix(color1, color2, props.fade) * in.lighting)/*, in.position.z*/};
}
)";
};

} // namespace shaders
} // namespace mbgl