/*  PCSX2 - PS2 Emulator for PCs
 *  Copyright (C) 2002-2023 PCSX2 Dev Team
 *
 *  PCSX2 is free software: you can redistribute it and/or modify it under the terms
 *  of the GNU Lesser General Public License as published by the Free Software Found-
 *  ation, either version 3 of the License, or (at your option) any later version.
 *
 *  PCSX2 is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 *  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 *  PURPOSE.  See the GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along with PCSX2.
 *  If not, see <http://www.gnu.org/licenses/>.
 */

#ifdef VERTEX_SHADER

layout(location = 0) in vec4 a_pos;
layout(location = 1) in vec2 a_tex;

layout(location = 0) out vec2 v_tex;

void main()
{
	gl_Position = vec4(a_pos.x, -a_pos.y, a_pos.z, a_pos.w);
	v_tex = a_tex;
}

#endif

#ifdef FRAGMENT_SHADER

layout(location = 0) in vec2 v_tex;

#if defined(ps_convert_rgba8_16bits) || defined(ps_convert_float32_32bits)
layout(location = 0) out uint o_col0;
#elif !defined(ps_datm1) && \
	!defined(ps_datm0) && \
	!defined(ps_convert_rgba8_float32) && \
	!defined(ps_convert_rgba8_float24) && \
	!defined(ps_convert_rgba8_float16) && \
	!defined(ps_convert_rgb5a1_float16) && \
	!defined(ps_convert_rgba8_float32_biln) && \
	!defined(ps_convert_rgba8_float24_biln) && \
	!defined(ps_convert_rgba8_float16_biln) && \
	!defined(ps_convert_rgb5a1_float16_biln) && \
	!defined(ps_depth_copy)
layout(location = 0) out vec4 o_col0;
#endif

layout(set = 0, binding = 0) uniform sampler2D samp0;

vec4 sample_c(vec2 uv)
{
	return texture(samp0, uv);
}

#ifdef ps_copy
void ps_copy()
{
	o_col0 = sample_c(v_tex);
}
#endif

#ifdef ps_depth_copy
void ps_depth_copy()
{
  gl_FragDepth = sample_c(v_tex).r;
}
#endif

#ifdef ps_filter_transparency
void ps_filter_transparency()
{
	vec4 c = sample_c(v_tex);
	o_col0 = vec4(c.rgb, 1.0);
}
#endif

#ifdef ps_convert_rgba8_16bits
// Need to be careful with precision here, it can break games like Spider-Man 3 and Dogs Life
void ps_convert_rgba8_16bits()
{
	uvec4 i = uvec4(sample_c(v_tex) * vec4(255.5f, 255.5f, 255.5f, 255.5f));

	o_col0 = ((i.x & 0x00F8u) >> 3) | ((i.y & 0x00F8u) << 2) | ((i.z & 0x00f8u) << 7) | ((i.w & 0x80u) << 8);
}
#endif

#ifdef ps_datm1
void ps_datm1()
{
	if(sample_c(v_tex).a < (127.5f / 255.0f)) // >= 0x80 pass
		discard;

}
#endif

#ifdef ps_datm0
void ps_datm0()
{
	if((127.5f / 255.0f) < sample_c(v_tex).a) // < 0x80 pass (== 0x80 should not pass)
		discard;
}
#endif

#ifdef ps_hdr_init
void ps_hdr_init()
{
	vec4 value = sample_c(v_tex);
	o_col0 = vec4(roundEven(value.rgb * 255.0f) / 65535.0f, value.a);
}
#endif

#ifdef ps_hdr_resolve
void ps_hdr_resolve()
{
	vec4 value = sample_c(v_tex);
	o_col0 = vec4(vec3(uvec3(value.rgb * 65535.5f) & 255u) / 255.0f, value.a);
}
#endif

#ifdef ps_convert_float32_32bits
void ps_convert_float32_32bits()
{
	// Convert a vec32 depth texture into a 32 bits UINT texture
	o_col0 = uint(exp2(32.0f) * sample_c(v_tex).r);
}
#endif

#ifdef ps_convert_float32_rgba8
void ps_convert_float32_rgba8()
{
	// Convert a vec32 depth texture into a RGBA color texture
	uint d = uint(sample_c(v_tex).r * exp2(32.0f));
	o_col0 = vec4(uvec4((d & 0xFFu), ((d >> 8) & 0xFFu), ((d >> 16) & 0xFFu), (d >> 24))) / vec4(255.0);
}
#endif

#ifdef ps_convert_float16_rgb5a1
void ps_convert_float16_rgb5a1()
{
	// Convert a vec32 (only 16 lsb) depth into a RGB5A1 color texture
	uint d = uint(sample_c(v_tex).r * exp2(32.0f));
	o_col0 = vec4(uvec4((d & 0x1Fu), ((d >> 5) & 0x1Fu), ((d >> 10) & 0x1Fu), (d >> 15) & 0x01u)) / vec4(32.0f, 32.0f, 32.0f, 1.0f);
}
#endif

float rgba8_to_depth32(vec4 unorm)
{
	uvec4 c = uvec4(unorm * vec4(255.5f));
	return float(c.r | (c.g << 8) | (c.b << 16) | (c.a << 24)) * exp2(-32.0f);
}

float rgba8_to_depth24(vec4 unorm)
{
	uvec3 c = uvec3(unorm.rgb * vec3(255.5f));
	return float(c.r | (c.g << 8) | (c.b << 16)) * exp2(-32.0f);
}

float rgba8_to_depth16(vec4 unorm)
{
	uvec2 c = uvec2(unorm.rg * vec2(255.5f));
	return float(c.r | (c.g << 8)) * exp2(-32.0f);
}

float rgb5a1_to_depth16(vec4 unorm)
{
	uvec4 c = uvec4(unorm * vec4(255.5f));
	return float(((c.r & 0xF8u) >> 3) | ((c.g & 0xF8u) << 2) | ((c.b & 0xF8u) << 7) | ((c.a & 0x80u) << 8)) * exp2(-32.0f);
}

#ifdef ps_convert_rgba8_float32
void ps_convert_rgba8_float32()
{
	// Convert an RGBA texture into a float depth texture
	gl_FragDepth = rgba8_to_depth32(sample_c(v_tex));
}
#endif

#ifdef ps_convert_rgba8_float24
void ps_convert_rgba8_float24()
{
	// Same as above but without the alpha channel (24 bits Z)

	// Convert an RGBA texture into a float depth texture
	gl_FragDepth = rgba8_to_depth24(sample_c(v_tex));
}
#endif

#ifdef ps_convert_rgba8_float16
void ps_convert_rgba8_float16()
{
	// Same as above but without the A/B channels (16 bits Z)

	// Convert an RGBA texture into a float depth texture
	gl_FragDepth = rgba8_to_depth16(sample_c(v_tex));
}
#endif

#ifdef ps_convert_rgb5a1_float16
void ps_convert_rgb5a1_float16()
{
	// Convert an RGB5A1 (saved as RGBA8) color to a 16 bit Z
	gl_FragDepth = rgb5a1_to_depth16(sample_c(v_tex));
}
#endif

#define SAMPLE_RGBA_DEPTH_BILN(CONVERT_FN) \
	ivec2 dims = textureSize(samp0, 0); \
	vec2 top_left_f = v_tex * vec2(dims) - 0.5f; \
	ivec2 top_left = ivec2(floor(top_left_f)); \
	ivec4 coords = clamp(ivec4(top_left, top_left + 1), ivec4(0), dims.xyxy - 1); \
	vec2 mix_vals = fract(top_left_f); \
	float depthTL = CONVERT_FN(texelFetch(samp0, coords.xy, 0)); \
	float depthTR = CONVERT_FN(texelFetch(samp0, coords.zy, 0)); \
	float depthBL = CONVERT_FN(texelFetch(samp0, coords.xw, 0)); \
	float depthBR = CONVERT_FN(texelFetch(samp0, coords.zw, 0)); \
	gl_FragDepth = mix(mix(depthTL, depthTR, mix_vals.x), mix(depthBL, depthBR, mix_vals.x), mix_vals.y);

#ifdef ps_convert_rgba8_float32_biln
void ps_convert_rgba8_float32_biln()
{
	// Convert an RGBA texture into a float depth texture
	SAMPLE_RGBA_DEPTH_BILN(rgba8_to_depth32);
}
#endif

#ifdef ps_convert_rgba8_float24_biln
void ps_convert_rgba8_float24_biln()
{
	// Same as above but without the alpha channel (24 bits Z)

	// Convert an RGBA texture into a float depth texture
	SAMPLE_RGBA_DEPTH_BILN(rgba8_to_depth24);
}
#endif

#ifdef ps_convert_rgba8_float16_biln
void ps_convert_rgba8_float16_biln()
{
	// Same as above but without the A/B channels (16 bits Z)

	// Convert an RGBA texture into a float depth texture
	SAMPLE_RGBA_DEPTH_BILN(rgba8_to_depth16);
}
#endif

#ifdef ps_convert_rgb5a1_float16_biln
void ps_convert_rgb5a1_float16_biln()
{
	// Convert an RGB5A1 (saved as RGBA8) color to a 16 bit Z
	SAMPLE_RGBA_DEPTH_BILN(rgb5a1_to_depth16);
}
#endif

#ifdef ps_convert_rgba_8i
layout(push_constant) uniform cb10
{
	uint SBW;
	uint DBW;
	uvec2 cb_pad1;
	float ScaleFactor;
	vec3 cb_pad2;
};

void ps_convert_rgba_8i()
{
	// Convert a RGBA texture into a 8 bits packed texture
	// Input column: 8x2 RGBA pixels
	// 0: 8 RGBA
	// 1: 8 RGBA
	// Output column: 16x4 Index pixels
	// 0: 8 R | 8 B
	// 1: 8 R | 8 B
	// 2: 8 G | 8 A
	// 3: 8 G | 8 A
	uvec2 pos = uvec2(gl_FragCoord.xy);

	// Collapse separate R G B A areas into their base pixel
	uvec2 block = (pos & ~uvec2(15u, 3u)) >> 1;
	uvec2 subblock = pos & uvec2(7u, 1u);
	uvec2 coord = block | subblock;

	// Compensate for potentially differing page pitch.
	uvec2 block_xy = coord / uvec2(64u, 32u);
	uint block_num = (block_xy.y * (DBW / 128u)) + block_xy.x;
	uvec2 block_offset = uvec2((block_num % (SBW / 64u)) * 64u, (block_num / (SBW / 64u)) * 32u);
	coord = (coord % uvec2(64u, 32u)) + block_offset;

	// Apply offset to cols 1 and 2
	uint is_col23 = pos.y & 4u;
	uint is_col13 = pos.y & 2u;
	uint is_col12 = is_col23 ^ (is_col13 << 1);
	coord.x ^= is_col12; // If cols 1 or 2, flip bit 3 of x

	if (floor(ScaleFactor) != ScaleFactor)
		coord = uvec2(vec2(coord) * ScaleFactor);
	else
		coord *= uvec2(ScaleFactor);

	vec4 pixel = texelFetch(samp0, ivec2(coord), 0);
	vec2  sel0 = (pos.y & 2u) == 0u ? pixel.rb : pixel.ga;
	float sel1 = (pos.x & 8u) == 0u ? sel0.x : sel0.y;
	o_col0 = vec4(sel1); // Divide by something here?
}
#endif

#ifdef ps_convert_clut_4
layout(push_constant) uniform cb10
{
	uvec2 offset;
	uint doffset;
	uint cb_pad1;
	float scale;
	vec3 cb_pad2;
};

void ps_convert_clut_4()
{
	// CLUT4 is easy, just two rows of 8x8.
	uint index = uint(gl_FragCoord.x) + doffset;
	uvec2 pos = uvec2(index % 8u, index / 8u);

	ivec2 final = ivec2(floor(vec2(offset + pos) * vec2(scale)));
	o_col0 = texelFetch(samp0, final, 0);
}
#endif

#ifdef ps_convert_clut_8
layout(push_constant) uniform cb10
{
	uvec2 offset;
	uint doffset;
	uint cb_pad1;
	float scale;
	vec3 cb_pad2;
};

void ps_convert_clut_8()
{
	uint index = min(uint(gl_FragCoord.x) + doffset, 255u);

	// CLUT is arranged into 8 groups of 16x2, with the top-right and bottom-left quadrants swapped.
	// This can probably be done better..
	uint subgroup = (index / 8u) % 4u;
	uvec2 pos;
	pos.x = (index % 8u) + ((subgroup >= 2u) ? 8u : 0u);
	pos.y = ((index / 32u) * 2u) + (subgroup % 2u);

	ivec2 final = ivec2(floor(vec2(offset + pos) * vec2(scale)));
	o_col0 = texelFetch(samp0, final, 0);
}
#endif

#ifdef ps_yuv
layout(push_constant) uniform cb10
{
	int EMODA;
	int EMODC;
};

void ps_yuv()
{
	vec4 i = sample_c(v_tex);
	vec4 o = vec4(0.0f);

	mat3 rgb2yuv;
	rgb2yuv[0] = vec3(0.587, -0.311, -0.419);
	rgb2yuv[1] = vec3(0.114, 0.500, -0.081);
	rgb2yuv[2] = vec3(0.299, -0.169, 0.500);

	vec3 yuv = rgb2yuv * i.gbr;

	float Y = float(0xDB)/255.0f * yuv.x + float(0x10)/255.0f;
	float Cr = float(0xE0)/255.0f * yuv.y + float(0x80)/255.0f;
	float Cb = float(0xE0)/255.0f * yuv.z + float(0x80)/255.0f;

	switch(EMODA)
	{
		case 0:
			o.a = i.a;
			break;
		case 1:
			o.a = Y;
			break;
		case 2:
			o.a = Y/2.0f;
			break;
		case 3:
			o.a = 0.0f;
			break;
	}

	switch(EMODC)
	{
		case 0:
			o.rgb = i.rgb;
			break;
		case 1:
			o.rgb = vec3(Y);
			break;
		case 2:
			o.rgb = vec3(Y, Cb, Cr);
			break;
		case 3:
			o.rgb = vec3(i.a);
			break;
	}

	o_col0 = o;
}
#endif

#if defined(ps_stencil_image_init_0) || defined(ps_stencil_image_init_1)

void main()
{
	o_col0 = vec4(0x7FFFFFFF);

	#ifdef ps_stencil_image_init_0
		if((127.5f / 255.0f) < sample_c(v_tex).a) // < 0x80 pass (== 0x80 should not pass)
			o_col0 = vec4(-1);
	#endif
	#ifdef ps_stencil_image_init_1
		if(sample_c(v_tex).a < (127.5f / 255.0f)) // >= 0x80 pass
			o_col0 = vec4(-1);
	#endif
}
#endif

#endif