#version 450

#include "compiled.inc"

uniform sampler2D tex;
uniform sampler2D tex2;
#ifdef _Veloc
uniform sampler2D sveloc;
#endif

in vec2 texCoord;
out vec4 fragColor;

const float SMAA_REPROJECTION_WEIGHT_SCALE = 30.0;

// TODO: Move to a utility
bool isInvalidValue(float v) {
	return (v != v) || (v > 65000.0) || (v < -65000.0);
}

bool hasInvalidValues(vec3 v) {
	return isInvalidValue(v.x) || isInvalidValue(v.y) || isInvalidValue(v.z);
}

void main() {
	vec4 current = textureLod(tex, texCoord, 0.0);
	
	current.rgb = clamp(current.rgb, vec3(0.0), vec3(10.0));
	current.a = clamp(current.a, 0.0, 1.0);
	if (hasInvalidValues(current.rgb)) {
		current = vec4(0.0, 0.0, 0.0, 1.0);
	}

#ifdef _Veloc
	// Velocity is assumed to be calculated for motion blur, so we need to inverse it for reprojection
	vec2 velocity = -textureLod(sveloc, texCoord, 0.0).rg;
	
	velocity = clamp(velocity, vec2(-1.0), vec2(1.0));
	if (isInvalidValue(velocity.x) || isInvalidValue(velocity.y)) {
		velocity = vec2(0.0);
	}

	#ifdef _InvY
	velocity.y = -velocity.y;
	#endif

	// Reproject current coordinates and fetch previous pixel
	vec2 prevCoord = texCoord + velocity;
	prevCoord = clamp(prevCoord, vec2(0.0), vec2(1.0));
	vec4 previous = textureLod(tex2, prevCoord, 0.0);
	
	previous.rgb = clamp(previous.rgb, vec3(0.0), vec3(10.0));
	previous.a = clamp(previous.a, 0.0, 1.0);
	if (hasInvalidValues(previous.rgb)) {
		previous = current; // Fallback to current frame if previous is corrupted
	}

	#ifdef _SMAA
		float currentAlpha = clamp(current.a, 0.0, 1.0);
		float previousAlpha = clamp(previous.a, 0.0, 1.0);
		float delta = abs(currentAlpha * currentAlpha - previousAlpha * previousAlpha) / 5.0;
		delta = clamp(delta, 0.0, 1.0); // Ensure delta is in valid range
	#else
		const float delta = 0.0;
	#endif
	
	float weight = 0.5 * clamp(1.0 - sqrt(max(delta, 0.0)) * SMAA_REPROJECTION_WEIGHT_SCALE, 0.0, 1.0);

	vec3 blended = mix(current.rgb, previous.rgb, weight);
	blended = clamp(blended, vec3(0.0), vec3(10.0));
	if (hasInvalidValues(blended)) {
		blended = current.rgb;
	}
	
	fragColor = vec4(blended, 1.0);
#else
	vec4 previous = textureLod(tex2, texCoord, 0.0);
	
	previous.rgb = clamp(previous.rgb, vec3(0.0), vec3(10.0));
	if (hasInvalidValues(previous.rgb)) {
		previous.rgb = current.rgb;
	}
	
	vec3 blended = mix(current.rgb, previous.rgb, 0.5);
	blended = clamp(blended, vec3(0.0), vec3(10.0));
	if (hasInvalidValues(blended)) {
		blended = current.rgb;
	}
	
	fragColor = vec4(blended, 1.0);
#endif
}