//#version 420 // Keep it for text editor detection

// Require for bit operation
//#extension GL_ARB_gpu_shader5 : enable

#define FMT_32 0
#define FMT_24 1
#define FMT_16 2

#define PS_PAL_FMT (PS_TEX_FMT >> 2)
#define PS_AEM_FMT (PS_TEX_FMT & 3)

// APITRACE_DEBUG enables forced pixel output to easily detect
// the fragment computed by primitive
#define APITRACE_DEBUG 0
// TEX_COORD_DEBUG output the uv coordinate as color. It is useful
// to detect bad sampling due to upscaling
//#define TEX_COORD_DEBUG
// Just copy directly the texture coordinate
#ifdef TEX_COORD_DEBUG
#define PS_TFX 1
#define PS_TCC 1
#endif

#define SW_BLEND (PS_BLEND_A || PS_BLEND_B || PS_BLEND_D)

#ifdef FRAGMENT_SHADER

in SHADER
{
    vec4 t;
    vec4 c;
    flat vec4 fc;
} PSin;

#define PSin_t (PSin.t)
#define PSin_c (PSin.c)
#define PSin_fc (PSin.fc)

// Same buffer but 2 colors for dual source blending
layout(location = 0, index = 0) out vec4 SV_Target0;
layout(location = 0, index = 1) out vec4 SV_Target1;

layout(binding = 0) uniform sampler2D TextureSampler;
layout(binding = 1) uniform sampler2D PaletteSampler;
layout(binding = 3) uniform sampler2D RtSampler; // note 2 already use by the image below

#ifndef DISABLE_GL42_image
#if PS_DATE > 0
// FIXME how to declare memory access
layout(r32i, binding = 2) uniform iimage2D img_prim_min;
// WARNING:
// You can't enable it if you discard the fragment. The depth is still
// updated (shadow in Shin Megami Tensei Nocturne)
//
// early_fragment_tests must still be enabled in the first pass of the 2 passes algo
// First pass search the first primitive that will write the bad alpha value. Value
// won't be written if the fragment fails the depth test.
//
// In theory the best solution will be do
// 1/ copy the depth buffer
// 2/ do the full depth (current depth writes are disabled)
// 3/ restore the depth buffer for 2nd pass
// Of course, it is likely too costly.
#if PS_DATE == 1 || PS_DATE == 2
layout(early_fragment_tests) in;
#endif

// I don't remember why I set this parameter but it is surely useless
//layout(pixel_center_integer) in vec4 gl_FragCoord;
#endif
#else
// use basic stencil
#endif


// Warning duplicated in both GLSL file
layout(std140, binding = 21) uniform cb21
{
    vec3 FogColor;
    float AREF;

    vec4 WH;

    vec2 _pad0;
    vec2 TA;

    uvec4 MskFix;

    uvec4 FbMask;

    vec3 _pad1;
    float Af;

    vec4 HalfTexel;

    vec4 MinMax;

    vec2 TextureScale;
    vec2 TC_OffsetHack;
};

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

vec4 sample_p(float idx)
{
    return texture(PaletteSampler, vec2(idx, 0.0f));
}

vec4 clamp_wrap_uv(vec4 uv)
{
    vec4 uv_out = uv;

#if PS_WMS == PS_WMT

#if PS_WMS == 2
    uv_out = clamp(uv, MinMax.xyxy, MinMax.zwzw);
#elif PS_WMS == 3
    uv_out = vec4((ivec4(uv * WH.xyxy) & ivec4(MskFix.xyxy)) | ivec4(MskFix.zwzw)) / WH.xyxy;
#endif

#else // PS_WMS != PS_WMT

#if PS_WMS == 2
    uv_out.xz = clamp(uv.xz, MinMax.xx, MinMax.zz);

#elif PS_WMS == 3
    uv_out.xz = vec2((ivec2(uv.xz * WH.xx) & ivec2(MskFix.xx)) | ivec2(MskFix.zz)) / WH.xx;

#endif

#if PS_WMT == 2
    uv_out.yw = clamp(uv.yw, MinMax.yy, MinMax.ww);

#elif PS_WMT == 3

    uv_out.yw = vec2((ivec2(uv.yw * WH.yy) & ivec2(MskFix.yy)) | ivec2(MskFix.ww)) / WH.yy;
#endif

#endif

    return uv_out;
}

mat4 sample_4c(vec4 uv)
{
    mat4 c;

    // Note: texture gather can't be used because of special clamping/wrapping
    // Also it doesn't support lod
    c[0] = sample_c(uv.xy);
    c[1] = sample_c(uv.zy);
    c[2] = sample_c(uv.xw);
    c[3] = sample_c(uv.zw);

    return c;
}

vec4 sample_4_index(vec4 uv)
{
    vec4 c;

    // Either GSdx will send a texture that contains a single channel
    // in this case the red channel is remapped as alpha channel
    //
    // Or we have an old RT (ie RGBA8) that contains index (4/8) in the alpha channel

    // Note: texture gather can't be used because of special clamping/wrapping
    // Also it doesn't support lod
    c.x = sample_c(uv.xy).a;
    c.y = sample_c(uv.zy).a;
    c.z = sample_c(uv.xw).a;
    c.w = sample_c(uv.zw).a;

    uvec4 i = uvec4(c * 255.0f + 0.5f); // Denormalize value

#if PS_PAL_FMT == 1
	// 4HL
    return vec4(i & 0xFu) / 255.0f;

#elif PS_PAL_FMT == 2
	// 4HH
    return vec4(i >> 4u) / 255.0f;

#else
    // Most of texture will hit this code so keep normalized float value

    // 8 bits
    return c;
#endif

}

mat4 sample_4p(vec4 u)
{
    mat4 c;

    c[0] = sample_p(u.x);
    c[1] = sample_p(u.y);
    c[2] = sample_p(u.z);
    c[3] = sample_p(u.w);

    return c;
}

vec4 sample_color(vec2 st, float q)
{
    //FIXME: maybe we can set gl_Position.w = q in VS
#if (PS_FST == 0)
    st /= q;
#endif

#if (PS_TCOFFSETHACK == 1)
    st += TC_OffsetHack.xy;
#endif

    vec4 t;
    mat4 c;
    vec2 dd;

    // FIXME I'm not sure this condition is useful (I think code will be optimized)
#if (PS_LTF == 0 && PS_AEM_FMT == FMT_32 && PS_PAL_FMT == 0 && PS_WMS < 2 && PS_WMT < 2)
    // No software LTF and pure 32 bits RGBA texure without special texture wrapping
    c[0] = sample_c(st);
#ifdef TEX_COORD_DEBUG
    c[0].rg = st.xy;
#endif

#else
    vec4 uv;

    if(PS_LTF != 0)
    {
        uv = st.xyxy + HalfTexel;
        dd = fract(uv.xy * WH.zw);
#if (PS_FST == 0)
        // Background in Shin Megami Tensei Lucifers
        // I suspect that uv isn't a standard number, so fract is outside of the [0;1] range
        // Note: it is free on GPU but let's do it only for float coordinate
        // Strangely Dx doesn't suffer from this issue.
        dd = clamp(dd, vec2(0.0f), vec2(1.0f));
#endif
    }
    else
    {
        uv = st.xyxy;
    }

    uv = clamp_wrap_uv(uv);

#if PS_PAL_FMT != 0
    c = sample_4p(sample_4_index(uv));
#else
    c = sample_4c(uv);
#endif

#ifdef TEX_COORD_DEBUG
    c[0].rg = uv.xy;
    c[1].rg = uv.xy;
    c[2].rg = uv.xy;
    c[3].rg = uv.xy;
#endif

#endif

	// PERF note: using dot product reduces by 1 the number of instruction
	// but I'm not sure it is equivalent neither faster.
	for (int i = 0; i < 4; i++)
	{
        //float sum = dot(c[i].rgb, vec3(1.0f));
#if (PS_AEM_FMT == FMT_24)
		c[i].a = ( (PS_AEM == 0) || any(bvec3(c[i].rgb))  ) ? TA.x : 0.0f;
		//c[i].a = ( (PS_AEM == 0) || (sum > 0.0f) ) ? TA.x : 0.0f;
#elif (PS_AEM_FMT == FMT_16)
		c[i].a = c[i].a >= 0.5 ? TA.y : ( (PS_AEM == 0) || any(bvec3(c[i].rgb)) ) ? TA.x : 0.0f;
		//c[i].a = c[i].a >= 0.5 ? TA.y : ( (PS_AEM == 0) || (sum > 0.0f) ) ? TA.x : 0.0f;
#endif
    }

#if(PS_LTF != 0)
    t = mix(mix(c[0], c[1], dd.x), mix(c[2], c[3], dd.x), dd.y);
#else
    t = c[0];
#endif

    // The 0.05f helps to fix the overbloom of sotc
    // I think the issue is related to the rounding of texture coodinate. The linear (from fixed unit)
    // interpolation could be slightly below the correct one.
    return trunc(t * 255.0f + 0.05f);
}

vec4 tfx(vec4 T, vec4 C)
{
    vec4 C_out;
    vec4 FxT = trunc(trunc(C) * T / 128.0f);

#if (PS_TFX == 0)
    C_out = FxT;
#elif (PS_TFX == 1)
    C_out = T;
#elif (PS_TFX == 2)
    C_out.rgb = FxT.rgb + C.a;
    C_out.a = T.a + C.a;
#elif (PS_TFX == 3)
    C_out.rgb = FxT.rgb + C.a;
    C_out.a = T.a;
#else
    C_out = C;
#endif

#if (PS_TCC == 0)
    C_out.a = C.a;
#endif

#if (PS_TFX == 0) || (PS_TFX == 2) || (PS_TFX == 3)
    // Clamp only when it is useful
    C_out = min(C_out, 255.0f);
#endif

    return C_out;
}

void atst(vec4 C)
{
    // FIXME use integer cmp
    float a = C.a;

#if (PS_ATST == 0) // never
    discard;
#elif (PS_ATST == 1) // always
    // nothing to do
#elif (PS_ATST == 2) // l
    if ((AREF - a - 0.5f) < 0.0f)
        discard;
#elif (PS_ATST == 3 ) // le
    if ((AREF - a + 0.5f) < 0.0f)
        discard;
#elif (PS_ATST == 4) // e
    if ((0.5f - abs(a - AREF)) < 0.0f)
        discard;
#elif (PS_ATST == 5) // ge
    if ((a-AREF + 0.5f) < 0.0f)
        discard;
#elif (PS_ATST == 6) // g
    if ((a-AREF - 0.5f) < 0.0f)
        discard;
#elif (PS_ATST == 7) // ne
    if ((abs(a - AREF) - 0.5f) < 0.0f)
        discard;
#endif
}

void fog(inout vec4 C, float f)
{
#if PS_FOG != 0
    C.rgb = trunc(mix(FogColor, C.rgb, f));
#endif
}

vec4 ps_color()
{
    vec4 T = sample_color(PSin_t.xy, PSin_t.w);

#if PS_IIP == 1
    vec4 C = tfx(T, PSin_c);
#else
    vec4 C = tfx(T, PSin_fc);
#endif

    atst(C);

    fog(C, PSin_t.z);

#if (PS_CLR1 != 0) // needed for Cd * (As/Ad/F + 1) blending modes
    C.rgb = vec3(255.0f);
#endif

    return C;
}

void ps_fbmask(inout vec4 C)
{
    // FIXME do I need special case for 16 bits
#if PS_FBMASK
    vec4 RT = trunc(texelFetch(RtSampler, ivec2(gl_FragCoord.xy), 0) * 255.0f + 0.1f);
    C = vec4((uvec4(C) & ~FbMask) | (uvec4(RT) & FbMask));
#endif
}

void ps_blend(inout vec4 Color, float As)
{
#if SW_BLEND
    vec4 RT = trunc(texelFetch(RtSampler, ivec2(gl_FragCoord.xy), 0) * 255.0f + 0.1f);

#if PS_DFMT == FMT_24
    float Ad = 1.0f;
#else
    // FIXME FMT_16 case
    // FIXME Ad or Ad * 2?
    float Ad = RT.a / 128.0f;
#endif

    // Let the compiler do its jobs !
    vec3 Cd = RT.rgb;
    vec3 Cs = Color.rgb;

#if PS_BLEND_A == 0
    vec3 A = Cs;
#elif PS_BLEND_A == 1
    vec3 A = Cd;
#else
    vec3 A = vec3(0.0f);
#endif

#if PS_BLEND_B == 0
    vec3 B = Cs;
#elif PS_BLEND_B == 1
    vec3 B = Cd;
#else
    vec3 B = vec3(0.0f);
#endif

#if PS_BLEND_C == 0
    float C = As;
#elif PS_BLEND_C == 1
    float C = Ad;
#else
    float C = Af;
#endif

#if PS_BLEND_D == 0
    vec3 D = Cs;
#elif PS_BLEND_D == 1
    vec3 D = Cd;
#else
    vec3 D = vec3(0.0f);
#endif

#if PS_BLEND_A == PS_BLEND_B
    Color.rgb = D;
#else
    Color.rgb = trunc((A - B) * C + D);
#endif

    // FIXME dithering

    // Correct the Color value based on the output format
#if PS_COLCLIP == 0 && PS_HDR == 0
    // Standard Clamp
    Color.rgb = clamp(Color.rgb, vec3(0.0f), vec3(255.0f));
#endif

    // FIXME rouding of negative float?
    // compiler uses trunc but it might need floor

    // Warning: normally blending equation is mult(A, B) = A * B >> 7. GPU have the full accuracy
    // GS: Color = 1, Alpha = 255 => output 1
    // GPU: Color = 1/255, Alpha = 255/255 * 255/128 => output 1.9921875
#if PS_DFMT == FMT_16
    // In 16 bits format, only 5 bits of colors are used. It impacts shadows computation of Castlevania

    Color.rgb = vec3(ivec3(Color.rgb) & ivec3(0xF8));
#elif PS_COLCLIP == 1 && PS_HDR == 0
    Color.rgb = vec3(ivec3(Color.rgb) & ivec3(0xFF));
#endif

#endif
}

void ps_main()
{
#if ((PS_DATE & 3) == 1 || (PS_DATE & 3) == 2) && !defined(DISABLE_GL42_image)

#if PS_WRITE_RG == 1
    // Pseudo 16 bits access.
    float rt_a = texelFetch(RtSampler, ivec2(gl_FragCoord.xy), 0).g;
#else
    float rt_a = texelFetch(RtSampler, ivec2(gl_FragCoord.xy), 0).a;
#endif

#if (PS_DATE & 3) == 1
    // DATM == 0: Pixel with alpha equal to 1 will failed
    bool bad = (127.5f / 255.0f) < rt_a;
#elif (PS_DATE & 3) == 2
    // DATM == 1: Pixel with alpha equal to 0 will failed
    bool bad = rt_a < (127.5f / 255.0f);
#endif

    if (bad) {
#if PS_DATE >= 5
        discard;
#else
        imageStore(img_prim_min, ivec2(gl_FragCoord.xy), ivec4(-1));
        return;
#endif
    }

#endif

#if PS_DATE == 3 && !defined(DISABLE_GL42_image)
    int stencil_ceil = imageLoad(img_prim_min, ivec2(gl_FragCoord.xy)).r;
    // Note gl_PrimitiveID == stencil_ceil will be the primitive that will update
    // the bad alpha value so we must keep it.

    if (gl_PrimitiveID > stencil_ceil) {
        discard;
    }
#endif

    vec4 C = ps_color();
#if (APITRACE_DEBUG & 1) == 1
    C.r = 255f;
#endif
#if (APITRACE_DEBUG & 2) == 2
    C.g = 255f;
#endif
#if (APITRACE_DEBUG & 4) == 4
    C.b = 255f;
#endif
#if (APITRACE_DEBUG & 8) == 8
    C.a = 128f;
#endif

#if PS_SHUFFLE
    uvec4 denorm_c = uvec4(C);
    uvec2 denorm_TA = uvec2(vec2(TA.xy) * 255.0f + 0.5f);

    // Write RB part. Mask will take care of the correct destination
#if PS_READ_BA
    C.rb = C.bb;
#else
    C.rb = C.rr;
#endif

    // FIXME precompute my_TA & 0x80

    // Write GA part. Mask will take care of the correct destination
    // Note: GLSL 4.50/GL_EXT_shader_integer_mix support a mix instruction to select a component\n"
    // However Nvidia emulate it with an if (at least on kepler arch) ...\n"
#if PS_READ_BA
    // bit field operation requires GL4 HW. Could be nice to merge it with step/mix below
    // uint my_ta = (bool(bitfieldExtract(denorm_c.a, 7, 1))) ? denorm_TA.y : denorm_TA.x;
    // denorm_c.a = bitfieldInsert(denorm_c.a, bitfieldExtract(my_ta, 7, 1), 7, 1);
    // c.ga = vec2(float(denorm_c.a));

    if (bool(denorm_c.a & 0x80u))
        C.ga = vec2(float((denorm_c.a & 0x7Fu) | (denorm_TA.y & 0x80u)));
    else
        C.ga = vec2(float((denorm_c.a & 0x7Fu) | (denorm_TA.x & 0x80u)));

#else
    if (bool(denorm_c.g & 0x80u))
        C.ga = vec2(float((denorm_c.g & 0x7Fu) | (denorm_TA.y & 0x80u)));
    else
        C.ga = vec2(float((denorm_c.g & 0x7Fu) | (denorm_TA.x & 0x80u)));

    // Nice idea but step/mix requires 4 instructions
    // set / trunc / I2F / Mad
    //
    // float sel = step(128.0f, c.g);
    // vec2 c_shuffle = vec2((denorm_c.gg & 0x7Fu) | (denorm_TA & 0x80u));
    // c.ga = mix(c_shuffle.xx, c_shuffle.yy, sel);
#endif

#endif

    // Must be done before alpha correction
    float alpha_blend = C.a / 128.0f;

    // Correct the ALPHA value based on the output format
#if (PS_DFMT == FMT_16)
    float A_one = 128.0f; // alpha output will be 0x80
    C.a = (PS_FBA != 0) ? A_one : step(128.0f, C.a) * A_one;
#elif (PS_DFMT == FMT_32) && (PS_FBA != 0)
    if(C.a < 128.0f) C.a += 128.0f;
#endif

    // Get first primitive that will write a failling alpha value
#if PS_DATE == 1 && !defined(DISABLE_GL42_image)
    // DATM == 0
    // Pixel with alpha equal to 1 will failed (128-255)
    if (C.a > 127.5f) {
        imageAtomicMin(img_prim_min, ivec2(gl_FragCoord.xy), gl_PrimitiveID);
    }
    return;
#elif PS_DATE == 2 && !defined(DISABLE_GL42_image)
    // DATM == 1
    // Pixel with alpha equal to 0 will failed (0-127)
    if (C.a < 127.5f) {
        imageAtomicMin(img_prim_min, ivec2(gl_FragCoord.xy), gl_PrimitiveID);
    }
    return;
#endif

    ps_blend(C, alpha_blend);

    ps_fbmask(C);

#if PS_HDR == 1
    // Use negative value to avoid overflow of the texture (in accumulation mode)
    // Note: code were initially done for an Half-Float texture. Due to overflow
    // the texture was upgraded to a full float. Maybe this code is useless now!
    // Good testcase is castlevania
    if (any(greaterThan(C.rgb, vec3(128.0f)))) {
        C.rgb = (C.rgb - 256.0f);
    }
#endif
    SV_Target0 = C / 255.0f;
    SV_Target1 = vec4(alpha_blend);
}

#endif