#version 330

// Input vertex attributes (from vertex shader)
in vec2 fragTexCoord;
in vec4 fragColor;

// Input uniform values
uniform sampler2D texture0;
uniform vec4 colDiffuse;

uniform float u_time;
uniform float u_glitchIntensity;
uniform vec2 u_resolution;
uniform int u_preset;

// Output fragment color
out vec4 finalColor;

void main()
{
    vec2 uv = fragTexCoord;

    // 1. Digital Glitch / Tactical Chromatic Aberration
    float glitch = (u_preset >= 2) ? clamp(u_glitchIntensity, 0.0, 1.0) : 0.0;
    if (glitch > 0.001)
    {
        // Horizontal line slice displacement
        float slice = step(0.68, sin(uv.y * 42.0 + u_time * 30.0));
        float sliceOffset = (slice * 2.0 - 1.0) * 0.015 * glitch;
        uv.x += sliceOffset;

        // Chromatic RGB separation
        float split = 0.010 * glitch;
        float r = texture(texture0, vec2(uv.x + split, uv.y)).r;
        float g = texture(texture0, uv).g;
        float b = texture(texture0, vec2(uv.x - split, uv.y)).b;
        finalColor = vec4(r, g, b, 1.0);
    }
    else
    {
        finalColor = texture(texture0, uv);
    }

    // 2. Tactical Color Grading (High Contrast Monochrome + Vivid Crimson Accent)
    // Desaturate non-red tones toward tactical gunmetal/monochrome
    float luma = dot(finalColor.rgb, vec3(0.299, 0.587, 0.114));
    
    // Check if the color is an intentional tactical accent (Crimson, Cobalt EMP, Amber, Acid, Violet)
    float maxC = max(finalColor.r, max(finalColor.g, finalColor.b));
    float minC = min(finalColor.r, min(finalColor.g, finalColor.b));
    float sat = (maxC > 0.05) ? ((maxC - minC) / maxC) : 0.0;
    bool isTacticalAccent = (sat > 0.36) || (finalColor.r > 0.35 && finalColor.r > finalColor.g * 1.3);
    
    if (!isTacticalAccent)
    {
        // Pull low-saturation environmental surfaces toward high-contrast monochrome steel
        vec3 mono = vec3(luma);
        finalColor.rgb = mix(finalColor.rgb, mono, 0.80);
    }

    // Enhance contrast (crush deep blacks, crispen bright highlights)
    finalColor.rgb = (finalColor.rgb - 0.5) * 1.18 + 0.5;
    finalColor.rgb = clamp(finalColor.rgb, 0.0, 1.0);

    // 3. Cinematic Corner Vignette (Tactical Helmet Visor Shadow)
    float d = distance(uv, vec2(0.5, 0.5));
    float vignette = smoothstep(0.78, 0.32, d);
    finalColor.rgb *= mix(0.40, 1.0, vignette);

    // 4. Subtle Tactical CRT Scanlines (Ultra mode only)
    if (u_preset >= 2)
    {
        float scanline = sin(uv.y * u_resolution.y * 1.5) * 0.025;
        finalColor.rgb -= scanline;
    }

    finalColor.a = 1.0;
}