// NOTE(allen): Changes durring this jam
// added R_StringBaselineCapped
// added R_StringCapped
// changed R_SetClip
// changed R_Begin
// added R_GetClip
// added R_PushClip

////////////////////////////////
// NOTE(allen): Internal types

typedef struct R_GL_Vertex R_GL_Vertex;
struct R_GL_Vertex
{
    v2 xy;
    v3 uvw;
    v4 rgba;
};

typedef struct R_GL_State R_GL_State;
struct R_GL_State
{
    v2 render_resolution;
    
    GLuint vertex_buffer;
    
    R_GL_Vertex *vertex_memory;
    u64 vertex_count;
    u64 vertex_max;
    
    R_Font *selected_font;
    u32 selected_font_texture;
    
    Rect clip;
};

typedef struct R_GL_Bind R_GL_Bind;
struct R_GL_Bind
{
    char *name;
    b32 is_uniform;
    u32 size;
    GLint v;
    u32 offset;
    u32 total_size;
};


////////////////////////////////
// NOTE(allen): Shader

global char shader_header[] = "#version 330\n";

global char shader_vertex_mono_texture[] = 
"in vec2 vert_xy;\n"
"in vec3 vert_uvw;\n"
"in vec4 vert_c;\n"
"out vec3 frag_uvw;\n"
"out vec4 frag_c;\n"
"uniform vec2 inv_half_dim;\n"
"void main()\n"
"{\n"
" gl_Position.x = (vert_xy.x*inv_half_dim.x) - 1;\n"
" gl_Position.y = 1 - (vert_xy.y*inv_half_dim.y);\n"
" gl_Position.z = 0;\n"
" gl_Position.w = 1;\n"
" frag_uvw = vert_uvw;\n"
" frag_c = vert_c;\n"
"}\n"
;

global char shader_fragment_mono_texture[] = 
"in vec3 frag_uvw;\n"
"in vec4 frag_c;\n"
"out vec4 out_c;\n"
"uniform sampler2DArray tex;\n"
"void main()\n"
"{\n"
" float v = texture(tex, frag_uvw).r;\n"
" out_c = vec4(frag_c.rgb, frag_c.a*v);\n"
"}\n"
;

#define R_GL_Bind_Members(N,u,off) R_GL_Bind N;
#define R_GL_Bind_Values(N,u,off) {#N,u,off},

#define R_GL_Mono_Texture_Binds(X)\
X(vert_xy , 0, 2)\
X(vert_uvw, 0, 3)\
X(vert_c  , 0, 4)\
X(inv_half_dim, 1, 0)\
X(tex         , 1, 0)

typedef struct R_GL_Mono_Texture R_GL_Mono_Texture;
struct R_GL_Mono_Texture
{
    R_GL_Mono_Texture_Binds(R_GL_Bind_Members)
};
global R_GL_Mono_Texture r_gl_mono_texture = {
    R_GL_Mono_Texture_Binds(R_GL_Bind_Values)
};

////////////////////////////////
// NOTE(allen): Main frame setup

global R_GL_State *global_render = 0;

internal GLuint
_R_CompilerShader(GLenum shader_kind, char *source)
{
    GLuint shader = glCreateShader(shader_kind);
    GLchar *sources[] = {shader_header, source};
    glShaderSource(shader, 2, sources, 0);
    glCompileShader(shader);
    
    i32 log_length = 0;
    glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &log_length);
    char error[1024] = {0};
    log_length = ClampTop(log_length, sizeof(error));
    glGetShaderInfoLog(shader, log_length, 0, error);
    Assert(log_length == 0);
    
    return(shader);
}

internal void
R_Init(M_Arena *arena)
{
    global_render = PushArrayZero(arena, R_GL_State, 1);
    LoadAllOpenGLProcedures();
    
    glEnable(GL_SCISSOR_TEST);
    glEnable(GL_BLEND);
    glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
    
    // NOTE(allen): vertex array
    GLint vao;
    glGenVertexArrays(1, &vao);
    glBindVertexArray(vao);
    
    // NOTE(allen): shader
    GLuint vertex_shader   = _R_CompilerShader(GL_VERTEX_SHADER  , shader_vertex_mono_texture  );
    GLuint fragment_shader = _R_CompilerShader(GL_FRAGMENT_SHADER, shader_fragment_mono_texture);
    
    GLuint program = glCreateProgram();
    glAttachShader(program, vertex_shader);
    glAttachShader(program, fragment_shader);
    glLinkProgram(program);
    glDeleteShader(vertex_shader);
    glDeleteShader(fragment_shader);
    
    i32 log_length = 0;
    glGetProgramiv(program, GL_INFO_LOG_LENGTH, &log_length);
    char error[1024] = {0};
    log_length = ClampTop(log_length, sizeof(error));
    glGetProgramInfoLog(program, log_length, 0, error);
    Assert(log_length == 0);
    
    {
        u64 bind_count = sizeof(r_gl_mono_texture)/sizeof(R_GL_Bind);
        R_GL_Bind *binds = (R_GL_Bind*)&r_gl_mono_texture;
        
        u32 total_size = 0;
        R_GL_Bind *bind = binds;
        for (u64 i = 0; i < bind_count; i += 1, bind += 1)
        {
            if (!bind->is_uniform)
            {
                total_size += bind->size*sizeof(f32);
            }
        }
        
        u64 offset = 0;
        bind = binds;
        for (u64 i = 0; i < bind_count; i += 1, bind += 1)
        {
            if (bind->is_uniform)
            {
                bind->v = glGetUniformLocation(program, bind->name);
            }
            else
            {
                bind->v = glGetAttribLocation(program, bind->name);
                bind->offset = offset;
                bind->total_size = total_size;
                offset += bind->size*sizeof(f32);
            }
        }
    }
    
    glUseProgram(program);
    glUniform1i(r_gl_mono_texture.tex.v, 0);
    
    
    // NOTE(allen): vertex buffer
    glGenBuffers(1, &global_render->vertex_buffer);
    glBindBuffer(GL_ARRAY_BUFFER, global_render->vertex_buffer);
    
    
    // NOTE(allen): increase this number for bigger batches; keep multiple of 3
    global_render->vertex_max = 4095;
    global_render->vertex_memory = PushArray(arena, R_GL_Vertex, global_render->vertex_max);
    glBufferData(GL_ARRAY_BUFFER, global_render->vertex_max*sizeof(R_GL_Vertex), 0, GL_DYNAMIC_DRAW);
    
    
    // NOTE(allen): vertex attributes
    {
        u64 bind_count = sizeof(r_gl_mono_texture)/sizeof(R_GL_Bind);
        R_GL_Bind *bind = (R_GL_Bind*)&r_gl_mono_texture;
        for (u64 i = 0; i < bind_count; i += 1, bind += 1)
        {
            if (!bind->is_uniform)
            {
                glEnableVertexAttribArray(bind->v);
                glVertexAttribPointer(bind->v, bind->size, GL_FLOAT, GL_FALSE, bind->total_size, PtrFromInt(bind->offset));
            }
        }
    }
    
    // NOTE(allen): setup texture download alignment
    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    
    // NOTE(allen): select null font
    global_render->selected_font = 0;
    global_render->selected_font_texture = 0;
}

internal void
_R_Flush(void)
{
    if (global_render->vertex_count > 0)
    {
        glBufferSubData(GL_ARRAY_BUFFER, 0, global_render->vertex_count*sizeof(R_GL_Vertex), global_render->vertex_memory);
        glDrawArrays(GL_TRIANGLES, 0, global_render->vertex_count);
        global_render->vertex_count = 0;
    }
}

internal R_GL_Vertex*
_R_AllocVertices(u64 count)
{
    Assert(count <= global_render->vertex_max);
    if (global_render->vertex_count + count > global_render->vertex_max)
    {
        _R_Flush();
    }
    
    R_GL_Vertex *result = global_render->vertex_memory + global_render->vertex_count;
    global_render->vertex_count += count;
    return(result);
}

internal void
R_Begin(v2 render_size, v3 color)
{
    global_render->render_resolution = render_size;
    R_SetClip(MakeRect(0.f, 0.f, V2Expand(render_size)));
    glViewport(0, 0, render_size.x, render_size.y);
    glClearColor(color.r, color.g, color.b, 1);
    glClear(GL_COLOR_BUFFER_BIT);
    
    glUniform2f(r_gl_mono_texture.inv_half_dim.v, 2.f/render_size.x, 2.f/render_size.y);
}

internal void
R_End(void)
{
    _R_Flush();
    os->RefreshScreen();
}

internal Rect
R_GetClip(void)
{
    return(global_render->clip);
}

internal Rect
R_SetClip(Rect rect)
{
    _R_Flush();
    glScissor((GLint)rect.x0, (GLint)(global_render->render_resolution.y - rect.y1),
              (GLint)(rect.x1 - rect.x0), (GLint)(rect.y1 - rect.y0));
    Rect result = global_render->clip;
    global_render->clip = rect;
    return(result);
}

internal Rect
R_PushClip(Rect rect)
{
    Rect intersected = RectIntersect(rect, global_render->clip);
    Rect result = R_SetClip(intersected);
    return(result);
}


////////////////////////////////
// NOTE(allen): Font

#define STB_TRUETYPE_IMPLEMENTATION
#include "ext/stb_truetype.h"

internal void
_R_TextureArraySetDataSlice(u32 index, u8 *data, u32 width, u32 height)
{
    glTexSubImage3D(GL_TEXTURE_2D_ARRAY, 0,
                    0, 0, index,
                    width, height, 1,
                    GL_RED, GL_UNSIGNED_BYTE, data);
}

internal void
_R_BaseInitFont(R_Font *font)
{
    // NOTE(allen): init
    font->initialized = 1;
    MemoryZeroArray(font->glyph);
    MemoryZeroArray(font->advance);
    
    // NOTE(allen): font metrics
    font->top_to_baseline = 0.f;
    font->baseline_to_next_top = 0.f;
    
    // NOTE(allen): setup texture
    glGenTextures(1, &font->var[0]);
    glBindTexture(GL_TEXTURE_2D_ARRAY, font->var[0]);
    glTexImage3D(GL_TEXTURE_2D_ARRAY, 0, GL_R8, 32, 64, 128, 0, GL_RED, GL_UNSIGNED_BYTE, 0);
    glTexParameteri(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_WRAP_T, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_MAX_LEVEL, 3);
    
    // NOTE(allen): full white at slice 0
    local_persist u8 temp_buffer[32*64] = {0};
    if (temp_buffer[0] == 0)
    {
        MemorySet(temp_buffer, 0xFF, sizeof(temp_buffer));
    }
    _R_TextureArraySetDataSlice(0, temp_buffer, 32, 64);
}

internal void
R_InitUserFont(R_Font *font)
{
    _R_BaseInitFont(font);
    glBindTexture(GL_TEXTURE_2D_ARRAY, global_render->selected_font_texture);
}

internal void
R_ReleaseFont(R_Font *font)
{
    font->initialized = 0;
    glDeleteTextures(1, &font->var[0]);
    if (global_render->selected_font == font)
    {
        global_render->selected_font = 0;
        global_render->selected_font_texture = 0;
        glBindTexture(GL_TEXTURE_2D_ARRAY, 0);
    }
}

internal void
R_InitFont(R_Font *font, String8 ttf_path, i32 size)
{
    font->initialized = 0;
    
    M_Arena *scratch = OS_GetScratch();
    
    void *data = 0;
    u64 data_len = 0;
    os->LoadEntireFile(scratch, ttf_path, &data, &data_len);
    
    if (data_len > 0)
    {
        stbtt_fontinfo stb_font;
        if (stbtt_InitFont(&stb_font, data, stbtt_GetFontOffsetForIndex(data, 0)))
        {
            // NOTE(allen): init
            _R_BaseInitFont(font);
            
            // NOTE(allen): font metrics
            f32 scale = stbtt_ScaleForPixelHeight(&stb_font, size);
            f32 em_scale = stbtt_ScaleForMappingEmToPixels(&stb_font, size);
            
            i32 ascent;
            i32 descent;
            i32 gap;
            stbtt_GetFontVMetrics(&stb_font, &ascent, &descent, &gap);
            
            font->top_to_baseline = ascent*em_scale;
            font->baseline_to_next_top = (gap - descent)*em_scale;
            
            
            // NOTE(allen): characters between [32,126]
            {
                R_Glyph_Box *glyph_ptr = font->glyph + 32;
                f32 *advance_ptr = font->advance + 32;
                for (u32 i = 32; i <= 126; i += 1, advance_ptr += 1, glyph_ptr += 1)
                {
                    i32 w;
                    i32 h;
                    i32 xoff;
                    i32 yoff;
                    
                    u8 *bitmap = stbtt_GetCodepointBitmap(&stb_font, 0, scale, i, &w, &h, &xoff, &yoff);
                    Assert(w <= 32);
                    Assert(h <= 64);
                    _R_TextureArraySetDataSlice(i, bitmap, w, h);
                    stbtt_FreeBitmap(bitmap, 0);
                    
                    i32 advance;
                    i32 lsb;
                    stbtt_GetCodepointHMetrics(&stb_font, i, &advance, &lsb);
                    
                    glyph_ptr->offset.x = xoff;
                    glyph_ptr->offset.y = yoff;
                    glyph_ptr->dim.x = w;
                    glyph_ptr->dim.y = h;
                    *advance_ptr = advance*em_scale;
                }
            }
            
            // NOTE(allen): update mipmaps
            glGenerateMipmap(GL_TEXTURE_2D_ARRAY);
            
            glBindTexture(GL_TEXTURE_2D_ARRAY, global_render->selected_font_texture);
        }
    }
    
    OS_ReleaseScratch(scratch);
}

internal b32
R_FontSetSlot(R_Font *font, u32 indx, u8 *bitmap, u32 width, u32 height,
              u32 xoff, u32 yoff, f32 advance)
{
    b32 result = 0;
    if (font->initialized)
    {
        if (0 < indx && indx <= 0x7F)
        {
            if (width <= 32 && height <= 64)
            {
                glBindTexture(GL_TEXTURE_2D_ARRAY, font->var[0]);
                _R_TextureArraySetDataSlice(indx, bitmap, width, height);
                
                font->glyph[indx].offset.x = xoff;
                font->glyph[indx].offset.y = yoff;
                font->glyph[indx].dim.x = width;
                font->glyph[indx].dim.y = height;
                font->advance[indx] = advance;
                
                glBindTexture(GL_TEXTURE_2D_ARRAY, global_render->selected_font_texture);
            }
        }
    }
    return(result);
}

internal void
R_FontUpdateMipmaps(R_Font *font)
{
    if (font != global_render->selected_font)
    {
        glBindTexture(GL_TEXTURE_2D_ARRAY, font->var[0]);
        glGenerateMipmap(GL_TEXTURE_2D_ARRAY);
        glBindTexture(GL_TEXTURE_2D_ARRAY, global_render->selected_font_texture);
    }
    else
    {
        glGenerateMipmap(GL_TEXTURE_2D_ARRAY);
    }
}

internal void
R_SelectFont(R_Font *font)
{
    if (global_render->selected_font != font)
    {
        _R_Flush();
        global_render->selected_font = font;
        global_render->selected_font_texture = font->var[0];
        glBindTexture(GL_TEXTURE_2D_ARRAY, global_render->selected_font_texture);
    }
}

internal v2
R_StringDimWithFont(R_Font *font, f32 scale, String8 string)
{
    v2 result = {0};
    u8 *ptr = string.str;
    u8 *end = ptr + string.size;
    f32 *advances = font->advance;
    for (;ptr < end; ptr += 1)
    {
        if (*ptr <= 0x7F)
        {
            result.x += f32Ceil(advances[*ptr]*scale);
        }
    }
    result.y = f32Ceil((font->top_to_baseline + font->baseline_to_next_top)*scale);
    return(result);
}

internal v2  
R_StringDim(f32 scale, String8 string)
{
    return(R_StringDimWithFont(global_render->selected_font, scale, string));
}


////////////////////////////////
// NOTE(allen): Draw

#define DupVert(n) vertices[n].xy = vertices[n - 2].xy
#define DupVertUVW(n) vertices[n].uvw = vertices[n - 2].uvw
#define DupVertC(n) vertices[n].c = vertices[n - 2].c

internal void
R_Rect(Rect rect, v3 color, f32 a)
{
    R_GL_Vertex *vertices = _R_AllocVertices(6);
    vertices[0].xy = rect.p0;
    vertices[1].xy = v2(rect.x1, rect.y0);
    vertices[2].xy = v2(rect.x0, rect.y1);
    
    DupVert(3); DupVert(4);
    vertices[5].xy = rect.p1;
    
    R_GL_Vertex *v = vertices;
    for (u64 i = 0; i < 6; i += 1, v += 1)
    {
        v->uvw = v3(0.f, 0.f, 0.f);
        v->rgba = v4(color.r, color.g, color.b, a);
    }
}

internal void
R_RectOutline(Rect rect, f32 thickness, v3 color, f32 a)
{
    Rect outer = rect;
    Rect inner = RectShrink(rect, thickness);
    
    R_GL_Vertex *vertices = _R_AllocVertices(24);
    vertices[0].xy = v2(outer.x0, outer.y0);
    vertices[1].xy = v2(inner.x0, inner.y0);
    vertices[2].xy = v2(outer.x1, outer.y0);
    
    DupVert(3); DupVert(4);
    vertices[5].xy = v2(inner.x1, inner.y0);
    
    DupVert(6); DupVert(7);
    vertices[8].xy = v2(outer.x1, outer.y1);
    
    DupVert(9); DupVert(10);
    vertices[11].xy = v2(inner.x1, inner.y1);
    
    DupVert(12); DupVert(13);
    vertices[14].xy = v2(outer.x0, outer.y1);
    
    DupVert(15); DupVert(16);
    vertices[17].xy = v2(inner.x0, inner.y1);
    
    DupVert(18); DupVert(19);
    vertices[20].xy = v2(outer.x0, outer.y0);
    
    DupVert(21); DupVert(22);
    vertices[23].xy = v2(inner.x0, inner.y0);
    
    R_GL_Vertex *v = vertices;
    for (u64 i = 0; i < 24; i += 1, v += 1)
    {
        v->uvw = v3(0.f, 0.f, 0.f);
        v->rgba = v4(color.r, color.g, color.b, a);
    }
}

internal v2
R_StringBaselineCapped(v2 p, f32 max_x, f32 scale, String8 string, v3 color, f32 a)
{
    v2 result = {0};
    R_Font *font = global_render->selected_font;
    if (font != 0 && font->initialized)
    {
        f32 *advances = font->advance;
        
        u8 tail[3] = {'.', '.', '.', };
        f32 x_tail = f32Ceil(advances['.']*scale)*3.f;
        b32 string_will_fit = 0;
        
        f32 x = p.x;
        if (x + x_tail <= max_x){
            u8 *ptr = string.str;
            u8 *end = ptr + string.size;
            R_Glyph_Box *glyphs = font->glyph;
            for (;ptr < end; ptr += 1)
            {
                top:
                if (*ptr <= 0x7F)
                {
                    f32 next_x = x + f32Ceil(advances[*ptr]*scale);
                    
                    // NOTE(allen): If the tail isn't going to fit after this
                    // we look ahead to see if the string fits. If not we switch
                    // to the tail now.
                    if (next_x + x_tail > max_x && !string_will_fit){
                        u8 *look_ahead_ptr = ptr + 1;
                        f32 look_ahead_x = next_x;
                        for (;look_ahead_ptr < end; look_ahead_ptr += 1){
                            look_ahead_x += f32Ceil(advances[*ptr]*scale);
                            if (look_ahead_x > max_x){
                                break;
                            }
                        }
                        if (look_ahead_x > max_x){
                            ptr = tail;
                            end = ptr + 3;
                            goto top;
                        }
                        
                        string_will_fit = 1;
                    }
                    
                    R_Glyph_Box *g = &glyphs[*ptr];
                    
                    Rect rect;
                    rect.x0 = x + g->offset.x*scale;
                    rect.y0 = p.y + g->offset.y*scale;
                    rect.x1 = rect.x0 + g->dim.x*scale;
                    rect.y1 = rect.y0 + g->dim.y*scale;
                    
                    v2 uv;
                    uv.x = g->dim.x*(1.f/32.f);
                    uv.y = g->dim.y*(1.f/64.f);
                    
                    f32 w = (*ptr);
                    
                    R_GL_Vertex *vertices = _R_AllocVertices(6);
                    vertices[0].xy = rect.p0;
                    vertices[0].uvw = v3(0.f, 0.f, w);
                    
                    vertices[1].xy = v2(rect.x1, rect.y0);
                    vertices[1].uvw = v3(uv.x, 0.f, w);
                    
                    vertices[2].xy = v2(rect.x0, rect.y1);
                    vertices[2].uvw = v3(0.f, uv.y, w);
                    
                    DupVert(3); DupVertUVW(3);
                    DupVert(4); DupVertUVW(4);
                    
                    vertices[5].xy = rect.p1;
                    vertices[5].uvw = v3(uv.x, uv.y, w);
                    
                    R_GL_Vertex *v = vertices;
                    for (u64 i = 0; i < 6; i += 1, v += 1)
                    {
                        v->rgba = v4(color.r, color.g, color.b, a);
                    }
                    
                    x = next_x;
                }
            }
        }
        result.x = x - p.x;
        result.y = f32Ceil((font->top_to_baseline + font->baseline_to_next_top)*scale);
    }
    return(result);
}

internal v2
R_StringCapped(v2 p, f32 max_x, f32 scale, String8 string, v3 color, f32 a)
{
    v2 result = {0};
    R_Font *font = global_render->selected_font;
    if (font != 0 && font->initialized)
    {
        p.y += font->top_to_baseline*scale;
        result = R_StringBaselineCapped(p, max_x, scale, string, color, a);
    }
    return(result);
}

internal v2
R_StringBaseline(v2 p, f32 scale, String8 string, v3 color, f32 a)
{
    return(R_StringBaselineCapped(p, Inf32(), scale, string, color, a));
}

internal v2
R_String(v2 p, f32 scale, String8 string, v3 color, f32 a)
{
    return(R_StringCapped(p, Inf32(), scale, string, color, a));
}