#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdarg.h>
#include <assert.h>

#include "mojoshader.h"

// Get basic wankery out of the way here...

#define STATICARRAYLEN(x) ( (sizeof ((x))) / (sizeof ((x)[0])) )

typedef unsigned int uint;  // this is a printf() helper. don't use for code.
typedef uint8_t uint8;
typedef uint32_t uint32;
typedef int32_t int32;

struct MOJOSHADER_glShader
{
    const MOJOSHADER_parseData *parseData;
    GLhandleARB handle;
    uint32 refcount;
};

typedef struct
{
    MOJOSHADER_shaderType shader_type;
    MOJOSHADER_uniform *uniform;
    GLuint location;
} UniformMap;

typedef struct
{
    MOJOSHADER_attribute *attribute;
    GLuint location;
} AttributeMap;

struct MOJOSHADER_glProgram
{
    const MOJOSHADER_glShader *vertex;
    const MOJOSHADER_glShader *fragment;
    GLhandleARB handle;
    uint32 uniform_count;
    UniformMap uniforms;
    uint32 attribute_count;
    AttributeMap attributes;
    uint32 refcount;
};

// Allocators...
static MOJOSHADER_malloc malloc_fn = NULL;
static MOJOSHADER_free free_fn = NULL;
static void *malloc_data = NULL;

// The constant register files...
// Man, it kills me how much memory this takes...
static float vs_register_file_f[8192 * 4];
static int vs_register_file_i[2047 * 4];
static uint8 vs_register_file_b[2047];
static float ps_register_file_f[8192 * 4];
static int ps_register_file_i[2047 * 4];
static uint8 ps_register_file_b[2047];

// GL stuff...
static MOJOSHADER_glProgram *bound_program = NULL;

// Error state...
static char error_buffer[1024] = { '\0' };

static void set_error(const char *str)
{
    snprintf(error_buffer, sizeof (error_buffer), "%s", str);
} // set_error


// #define this to force app to supply an allocator, so there's no reference
//  to the C runtime's malloc() and free()...
#if MOJOSHADER_FORCE_ALLOCATOR
#define internal_malloc NULL
#define internal_free NULL
#else
static void *internal_malloc(int bytes, void *d) { return malloc(bytes); }
static void internal_free(void *ptr, void *d) { free(ptr); }
#endif

static inline void *Malloc(const size_t len)
{
    void *retval = malloc_fn(len, malloc_data);
    if (retval == NULL)
        set_error("out of memory");
    return retval;
} // Malloc

static inline void Free(void *ptr)
{
    if (ptr != NULL)
        free_fn(ptr, malloc_data);
} // Free


const char *MOJOSHADER_glGetError(void)
{
    return error_buffer;
} // MOJOSHADER_glGetError


int MOJOSHADER_glInit(const char *_profile,
                      void *(*lookup)(const char *fnname),
                      MOJOSHADER_malloc m, MOJOSHADER_free f, void *d)
{
    error_buffer[0] = '\0';

    if (strcmp(_profile, MOJOSHADER_PROFILE_GLSL) != 0)
        profile = MOJOSHADER_PROFILE_GLSL;
    else
    {
        set_error("unknown profile");
        return 0;
    } // else

    // !!! FIXME: lookup glGetString(), check extensions.

    malloc_fn = (m == NULL) ? internal_malloc : m;
    free_fn = (f == NULL) ? internal_free : f;
    malloc_data = d;

    // !!! FIXME: lookup other entry points.

    memset(vs_register_file_f, '\0', sizeof (vs_register_file_f));
    memset(vs_register_file_i, '\0', sizeof (vs_register_file_i));
    memset(vs_register_file_b, '\0', sizeof (vs_register_file_b));
    memset(ps_register_file_f, '\0', sizeof (ps_register_file_f));
    memset(ps_register_file_i, '\0', sizeof (ps_register_file_i));
    memset(ps_register_file_b, '\0', sizeof (ps_register_file_b));

    MOJOSHADER_glBindProgram(NULL);

    return 1;
} // MOJOSHADER_glInit


MOJOSHADER_glShader *MOJOSHADER_glCompileShader(const unsigned char *tokenbuf,
                                                const unsigned int bufsize)
{
    MOJOSHADER_glShader *retval = NULL;
    GLhandleARB shader = 0;
    const MOJOSHADER_parseData *pd = MOJOSHADER_parse(profile, tokenbuf,
                                                      bufsize, malloc_fn,
                                                      free_fn, malloc_data);
    if (pd->error != NULL)
    {
        set_error(pd->error);
        goto compile_shader_fail;
    } // if

    retval = (MOJOSHADER_glShader *) Malloc(sizeof (MOJOSHADER_glShader));
    if (retval == NULL)
        goto compile_shader_fail;

    GLint ok = 0;
    const GLenum shader_type = (pd->shader_type == MOJOSHADER_TYPE_PIXEL) ? GL_FRAGMENT_SHADER_ARB : GL_VERTEX_SHADER_ARB;
    GLint shaderlen = (GLint) pd->output_len;
    shader = pglCreateShaderObjectARB(shader_type);

    pglShaderSourceARB(shader, 1, (const GLcharARB **) &pd->output, &shaderlen);
    pglCompileShaderARB(shader);
    pglGetObjectParameterivARB(shader, GL_OBJECT_COMPILE_STATUS_ARB, &ok);

    if (!ok)
    {
        GLsizei len = 0;
        pglGetInfoLogARB(shader, sizeof (error_buffer), &len,
                         (GLcharARB *) error_buffer);
        goto compile_shader_fail;
    } // if

    retval->parseData = pd;
    retval->handle = shader;
    retval->refcount = 1;
    return retval;

compile_shader_fail:
    MOJOSHADER_freeParseData(pd);
    Free(retval);
    if (shader != 0)
        pglDeleteObjectARB(shader);
    return NULL;
} // MOJOSHADER_glCompileShader


static void shader_unref(MOJOSHADER_glShader *shader)
{
    if (shader != NULL)
    {
        const uint32 refcount = program->refcount;
        if (refcount > 1)
            program->refcount--;
        else
        {
            pglDeleteObjectARB(shader->handle);
            MOJOSHADER_freeParseData(shader->parseData);
            Free(shader);
        } // else
    } // if
} // shader_unref


static void program_unref(MOJOSHADER_glProgram *program)
{
    if (program != NULL)
    {
        const uint32 refcount = program->refcount;
        if (refcount > 1)
            program->refcount--;
        else
        {
            pglDeleteObjectARB(program->handle);
            shader_unref(program->vertex);
            shader_unref(program->fragment);
            Free(program->attributes);
            Free(program->uniforms);
            Free(program);
        } // else
    } // if
} // program_unref


static void lookup_uniforms(MOJOSHADER_glProgram *program,
                            MOJOSHADER_glShader *shader)
{
    int i;
    const MOJOSHADER_parseData *pd = shader->parseData;
    const MOJOSHADER_uniforms *u = pd->uniforms;
    const MOJOSHADER_shaderType shader_type = pd->shader_type;

    for (i = 0; i < pd->uniform_count; i++)
    {
        const GLint loc = pglGetUniformLocationARB(program->handle, u[i].name);
        if (loc != -1)  // maybe the Uniform was optimized out?
        {
            UniformMap *map = &program->uniforms[program->uniform_count];
            map->shader_type = shader_type;
            map->uniform = &u[i];
            map->location = (GLuint) loc;
            program->uniform_count++;
        } // if
    } // for
} // lookup_uniforms


static void lookup_attributes(MOJOSHADER_glProgram *program)
{
    int i;
    const MOJOSHADER_parseData *pd = program->vertex->parseData;
    const MOJOSHADER_attributes *a = pd->attributes;

    for (i = 0; i < pd->attribute_count; i++)
    {
        const GLint loc = pglGetAttribLocationARB(program->handle, a->name);
        if (loc != -1)  // maybe the Attribute was optimized out?
        {
            AttributeMap *map = &program->attributes[program->attribute_count];
            map->attribute = &a[i];
            map->location = (GLuint) loc;
            program->attribute_count++;
        } // if
    } // for
} // lookup_attributes


MOJOSHADER_glProgram *MOJOSHADER_glLinkProgram(MOJOSHADER_glShader *vshader,
                                               MOJOSHADER_glShader *pshader)
{
    if ((vshader == NULL) && (pshader == NULL))
        return NULL;

    MOJOSHADER_glProgram *retval = NULL;
    const GLhandleARB program = pglCreateProgramObjectARB();

    if (vshader != NULL) pglAttachObjectARB(program, vshader->handle);
    if (pshader != NULL) pglAttachObjectARB(program, pshader->handle);

    pglLinkProgramARB(program);

    GLint ok = 0;
    pglGetObjectParameterivARB(program, GL_OBJECT_LINK_STATUS_ARB, &ok);
    if (!ok)
    {
        GLsizei len = 0;
        pglGetInfoLogARB(shader, sizeof (error_buffer), &len,
                         (GLcharARB *) error_buffer);
        goto link_program_fail;
    } // if

    retval = (MOJOSHADER_glProgram *) Malloc(sizeof (MOJOSHADER_glProgram));
    if (retval == NULL)
        goto link_program_fail;
    memset(retval, '\0', sizeof (MOJOSHADER_glProgram));

    int numregs = 0;
    if (vshader != NULL) numregs += vshader->parseData->uniform_count;
    if (pshader != NULL) numregs += pshader->parseData->uniform_count;
    retval->uniforms = (UniformMap *) Malloc(sizeof (UniformMap) * numregs);
    if (retval->uniforms == NULL)
        goto link_program_fail;
    memset(retval->uniforms, '\0', sizeof (UniformMap) * numregs);

    retval->handle = program;
    retval->vertex = vshader;
    retval->fragment = pshader;
    retval->refcount = 1;

    if (vshader != NULL)
    {
        retval->attributes = (AttributeMap *) Malloc(sizeof (AttributeMap) *
                                        vshader->parseData->attribute_count);
        if (retval->attributes == NULL)
            goto link_program_fail;

        lookup_attributes(retval);
        lookup_uniforms(retval, vshader);
        vshader->refcount++;
    } // if

    if (pshader != NULL)
    {
        lookup_uniforms(retval, pshader);
        pshader->refcount++;
    } // if

    return retval;

link_program_fail:
    if (retval != NULL)
    {
        Free(retval->uniforms);
        Free(retval->attributes);
        Free(retval);
    } // if

    pglDeleteObjectARB(program);
    return NULL;
} // MOJOSHADER_glLinkProgram


void MOJOSHADER_glBindProgram(MOJOSHADER_glProgram *program)
{
    GLhandleARB handle = 0;
    if (program != NULL)
    {
        handle = program->handle;
        program->refcount++;
    } // if

    // !!! FIXME: unbind client-side arrays.

    pglUseProgramObjectARB(handle);
    program_unref(bound_program);
    bound_program = program;
} // MOJOSHADER_glBindProgram


static inline uint maxuint(const uint a, const uint b)
{
    return ((a > b) ? a : b);
} // maxuint


void MOJOSHADER_glSetVertexShaderUniformF(unsigned int idx, const float *data,
                                          unsigned int vec4n)
{
    const uint maxregs = STATICARRAYLEN(vs_register_file_f) / 4;
    if (idx < maxregs)
    {
        const uint cpy = maxuint(maxregs - idx, vec4n) * sizeof (*data)) * 4;
        memcpy(vs_register_file_f + (idx * 4), data, cpy);
    } // if
} // MOJOSHADER_glSetVertexShaderUniformF


void MOJOSHADER_glSetVertexShaderUniformI(unsigned int idx, const int *data,
                                          unsigned int ivec4n)
{
    const uint maxregs = STATICARRAYLEN(vs_register_file_i) / 4;
    if (idx < maxregs)
    {
        const uint cpy = maxuint(maxregs - idx, ivec4n) * sizeof (*data)) * 4;
        memcpy(vs_register_file_i + (idx * 4), data, cpy);
    } // if
} // MOJOSHADER_glSetVertexShaderUniformI


void MOJOSHADER_glSetVertexShaderUniformB(unsigned int idx, const int *data,
                                          unsigned int bcount)
{
    const uint maxregs = STATICARRAYLEN(vs_register_file_f) / 4;
    if (idx < maxregs)
    {
        uint8 *wptr = vs_register_file_b + idx;
        uint8 *endptr = wptr + maxuint(maxregs - idx, bcount);
        while (wptr != endptr)
            *(wptr++) = *(data++) ? 1 : 0;
    } // if
} // MOJOSHADER_glSetVertexShaderUniformB


void MOJOSHADER_glSetPixelShaderUniformF(unsigned int idx, const float *data,
                                         unsigned int vec4n)
{
    const uint maxregs = STATICARRAYLEN(ps_register_file_f) / 4;
    if (idx < maxregs)
    {
        const uint cpy = maxuint(maxregs - idx, vec4n) * sizeof (*data)) * 4;
        memcpy(ps_register_file_f + (idx * 4), data, cpy);
    } // if
} // MOJOSHADER_glSetPixelShaderUniformF


void MOJOSHADER_glSetPixelShaderUniformI(unsigned int idx, const int *data,
                                         unsigned int ivec4n)
{
    const uint maxregs = STATICARRAYLEN(ps_register_file_i) / 4;
    if (idx < maxregs)
    {
        const uint cpy = maxuint(maxregs - idx, ivec4n) * sizeof (*data)) * 4;
        memcpy(ps_register_file_i + (idx * 4), data, cpy);
    } // if
} // MOJOSHADER_glSetPixelShaderUniformI


void MOJOSHADER_glSetPixelShaderUniformB(unsigned int idx, const int *data,
                                         unsigned int bcount)
{
    const uint maxregs = STATICARRAYLEN(ps_register_file_f) / 4;
    if (idx < maxregs)
    {
        uint8 *wptr = ps_register_file_b + idx;
        uint8 *endptr = wptr + maxuint(maxregs - idx, bcount);
        while (wptr != endptr)
            *(wptr++) = *(data++) ? 1 : 0;
    } // if
} // MOJOSHADER_glSetPixelShaderUniformB


static inline GLenum opengl_posattr_type(const MOJOSHADER_attributeType type)
{
    // we don't ever use the glVertexPointer() stream, so we just need to
    //  make the data types reasonably match, so the GL doesn't overrun
    //  the buffer when dereferencing it.

    switch (type)
    {
        case MOJOSHADER_ATTRIBUTE_BYTE: return GL_NONE;  // oh well.
        case MOJOSHADER_ATTRIBUTE_UBYTE: return GL_NONE;  // oh well.
        case MOJOSHADER_ATTRIBUTE_SHORT: return GL_SHORT;
        case MOJOSHADER_ATTRIBUTE_USHORT: return GL_SHORT;
        case MOJOSHADER_ATTRIBUTE_INT: return GL_INT;
        case MOJOSHADER_ATTRIBUTE_UINT: return GL_INT;
        case MOJOSHADER_ATTRIBUTE_FLOAT: return GL_FLOAT;
        case MOJOSHADER_ATTRIBUTE_DOUBLE: return GL_DOUBLE;
    } // switch

    return GL_NONE;  // oh well. Raises a GL error later.
} // opengl_posattr_type


static inline GLenum opengl_attr_type(const MOJOSHADER_attributeType type)
{
    switch (type)
    {
        case MOJOSHADER_ATTRIBUTE_BYTE: return GL_BYTE;
        case MOJOSHADER_ATTRIBUTE_UBYTE: return GL_UNSIGNED_BYTE;
        case MOJOSHADER_ATTRIBUTE_SHORT: return GL_SHORT;
        case MOJOSHADER_ATTRIBUTE_USHORT: return GL_USHORT;
        case MOJOSHADER_ATTRIBUTE_INT: return GL_INT;
        case MOJOSHADER_ATTRIBUTE_UINT: return GL_UNSIGNED_INT;
        case MOJOSHADER_ATTRIBUTE_FLOAT: return GL_FLOAT;
        case MOJOSHADER_ATTRIBUTE_DOUBLE: return GL_DOUBLE;
    } // switch

    return GL_NONE;  // oh well. Raises a GL error later.
} // opengl_attr_type


void MOJOSHADER_glSetVertexAttribute(MOJOSHADER_usage usage,
                                     int index, unsigned int size,
                                     MOJOSHADER_attributeType type,
                                     int normalized, unsigned int stride,
                                     const void *ptr)
{
    if ((bound_program == NULL) || (bound_program->vertex == NULL))
        return;

    // Since glVertexPointer() lacks the flexibility that we can get from
    //  glVertexAttribPointer(), we set POSITION0 to a generic vertex
    //  attribute, and the shaders we generate know to look there instead of
    //  GLSL's gl_Position global variable. But to keep the GL handy, we
    //  also set the best possible equivalent with glVertexPointer(). Messy.

    if ((usage == MOJOSHADER_USAGE_POSITION) && (index == 0))
    {
        // !!! FIXME: fails if size==1.
        pglVertexPointer(size, opengl_posattr_type(type), stride, ptr);
        pglEnableClientState(GL_VERTEX_ARRAY);
    } // if

    int i;
    GLuint gl_index = 0;
    for (i = 0; i < bound_program->attribute_count; i++)
    {
        const AttributeMap *map = &bound_program->attributes[i];
        const MOJOSHADER_attribute *a = map->attribute;

        // !!! FIXME: is this array guaranteed to be sorted by usage?
        // !!! FIXME:  if so, we can break out of the loop if a->usage > usage.

        if ((a->usage == usage) && (a->index == index))
        {
            gl_index = map->location;
            break;
        } // if
    } // for

    if (gl_index != 0)
    {
        const GLenum gl_type = opengl_attr_type(type);
        const GLboolean norm = (normalized) ? GL_TRUE : GL_FALSE;
        pglVertexAttribPointerARB(gl_index, size, gl_type, norm, stride, ptr);
        pglEnableVertexAttribArrayARB(gl_index);
    } // if
} // MOJOSHADER_glSetVertexAttribute


void MOJOSHADER_glProgramReady(void)
{
    int i;

    if (bound_program == NULL)
        return;  // nothing to do.

    // !!! FIXME: don't push Uniforms if we know they haven't changed.

    // push Uniforms to the program from our register files...
    for (i = 0; i < bound_program->uniform_count; i++)
    {
        const UniformMap *map = &bound_program->uniforms[i];
        const MOJOSHADER_uniform *u = map->uniform;
        const MOJOSHADER_uniformType type = u->type;
        const MOJOSHADER_shaderType shader_type = map->shader_type;
        const int index = u->index;
        const GLint location = map->location;

        if (shader_type == MOJOSHADER_TYPE_VERTEX)
        {
            if (type == MOJOSHADER_UNIFORM_FLOAT)
                pglUniform4fvARB(location, 1, &vs_register_file_f[index * 4]);
            else if (type == MOJOSHADER_UNIFORM_INT)
                pglUniform4ivARB(location, 1, &vs_register_file_i[index * 4]);
            else if (type == MOJOSHADER_UNIFORM_BOOL)
                pglUniform1iARB(location, vs_register_file_b[index]);
        } // if

        else if (shader_type == MOJOSHADER_TYPE_PIXEL)
        {
            if (type == MOJOSHADER_UNIFORM_FLOAT)
                pglUniform4fvARB(location, 1, &ps_register_file_f[index * 4]);
            else if (type == MOJOSHADER_UNIFORM_INT)
                pglUniform4ivARB(location, 1, &ps_register_file_i[index * 4]);
            else if (type == MOJOSHADER_UNIFORM_BOOL)
                pglUniform1iARB(location, ps_register_file_b[index]);
        } // else if
    } // for
} // MOJOSHADER_glProgramReady


void MOJOSHADER_glDeleteProgram(const MOJOSHADER_glProgram *program)
{
    program_unref(shader);
} // MOJOSHADER_glDeleteProgram


void MOJOSHADER_glDeleteShader(const MOJOSHADER_glShader *shader)
{
    shader_unref(shader);
} // MOJOSHADER_glDeleteShader


void MOJOSHADER_glDeinit(void)
{
    MOJOSHADER_glBindProgram(NULL);

    profile = NULL;
    malloc_fn = NULL;
    free_fn = NULL;
    malloc_data = NULL;
    error_buffer[0] = '\0';

    // !!! FIXME: NULL entry points.
} // MOJOSHADER_glDeinit

// end of mojoshader_opengl.c ...