/*

 * This file is part of mpv.

 * Parts based on MPlayer code by Reimar Döffinger.

 *

 * mpv 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 Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * mpv 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 Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with mpv.  If not, see <http://www.gnu.org/licenses/>.

 */

#include <stddef.h>

#include <stdint.h>

#include <stdlib.h>

#include <string.h>

#include <stdarg.h>

#include <assert.h>

#include "osdep/io.h"

#include "common/common.h"

#include "options/path.h"

#include "stream/stream.h"

#include "formats.h"

#include "utils.h"

// GLU has this as gluErrorString (we don't use GLU, as it is legacy-OpenGL)

static const char *gl_error_to_string(GLenum error)

{

    switch (error) {

    case GL_INVALID_ENUM: return "INVALID_ENUM";

    case GL_INVALID_VALUE: return "INVALID_VALUE";

    case GL_INVALID_OPERATION: return "INVALID_OPERATION";

    case GL_INVALID_FRAMEBUFFER_OPERATION: return "INVALID_FRAMEBUFFER_OPERATION";

    case GL_OUT_OF_MEMORY: return "OUT_OF_MEMORY";

    default: return "unknown";

    }

}

void gl_check_error(GL *gl, struct mp_log *log, const char *info)

{

    for (;;) {

        GLenum error = gl->GetError();

        if (error == GL_NO_ERROR)

            break;

        mp_msg(log, MSGL_ERR, "%s: OpenGL error %s.\n", info,

               gl_error_to_string(error));

    }

}

static int get_alignment(int stride)

{

    if (stride % 8 == 0)

        return 8;

    if (stride % 4 == 0)

        return 4;

    if (stride % 2 == 0)

        return 2;

    return 1;

}

// upload a texture, handling things like stride and slices

//  target: texture target, usually GL_TEXTURE_2D

//  format, type: texture parameters

//  dataptr, stride: image data

//  x, y, width, height: part of the image to upload

void gl_upload_tex(GL *gl, GLenum target, GLenum format, GLenum type,

                   const void *dataptr, int stride,

                   int x, int y, int w, int h)

{

    int bpp = gl_bytes_per_pixel(format, type);

    uintptr_t data = (uintptr_t)dataptr;

    int y_max = y + h;

    if (w <= 0 || h <= 0 || !bpp)

        return;

    mp_assert(stride > 0);

    gl->PixelStorei(GL_UNPACK_ALIGNMENT, get_alignment(stride));

    int slice = h;

    if (gl->mpgl_caps & MPGL_CAP_ROW_LENGTH) {

        // this is not always correct, but should work for MPlayer

        gl->PixelStorei(GL_UNPACK_ROW_LENGTH, stride / bpp);

    } else {

        if (stride != bpp * w)

            slice = 1; // very inefficient, but at least it works

    }

    for (; y + slice <= y_max; y += slice) {

        gl->TexSubImage2D(target, 0, x, y, w, slice, format, type, (void *)data);

        data += stride * slice;

    }

    if (y < y_max)

        gl->TexSubImage2D(target, 0, x, y, w, y_max - y, format, type, (void *)data);

    if (gl->mpgl_caps & MPGL_CAP_ROW_LENGTH)

        gl->PixelStorei(GL_UNPACK_ROW_LENGTH, 0);

    gl->PixelStorei(GL_UNPACK_ALIGNMENT, 4);

}

bool gl_read_fbo_contents(GL *gl, int fbo, int dir, GLenum format, GLenum type,

                          int w, int h, uint8_t *dst, int dst_stride)

{

    mp_assert(dir == 1 || dir == -1);

    if (fbo == 0 && gl->es)

        return false; // ES can't read from front buffer

    gl->BindFramebuffer(GL_FRAMEBUFFER, fbo);

    GLenum obj = fbo ? GL_COLOR_ATTACHMENT0 : GL_FRONT;

    gl->PixelStorei(GL_PACK_ALIGNMENT, 1);

    gl->ReadBuffer(obj);

    // reading by line allows flipping, and avoids stride-related trouble

    int y1 = dir > 0 ? 0 : h;

    for (int y = 0; y < h; y++)

        gl->ReadPixels(0, y, w, 1, format, type, dst + (y1 + dir * y) * dst_stride);

    gl->PixelStorei(GL_PACK_ALIGNMENT, 4);

    gl->BindFramebuffer(GL_FRAMEBUFFER, 0);

    return true;

}

static void gl_vao_enable_attribs(struct gl_vao *vao)

{

    GL *gl = vao->gl;

    for (int n = 0; n < vao->num_entries; n++) {

        const struct ra_renderpass_input *e = &vao->entries[n];

        GLenum type = 0;

        bool normalized = false;

        switch (e->type) {

        case RA_VARTYPE_INT:

            type = GL_INT;

            break;

        case RA_VARTYPE_FLOAT:

            type = GL_FLOAT;

            break;

        case RA_VARTYPE_BYTE_UNORM:

            type = GL_UNSIGNED_BYTE;

            normalized = true;

            break;

        default:

            abort();

        }

        mp_assert(e->dim_m == 1);

        gl->EnableVertexAttribArray(n);

        gl->VertexAttribPointer(n, e->dim_v, type, normalized,

                                vao->stride, (void *)(intptr_t)e->offset);

    }

}

void gl_vao_init(struct gl_vao *vao, GL *gl, int stride,

                 const struct ra_renderpass_input *entries,

                 int num_entries)

{

    mp_assert(!vao->vao);

    mp_assert(!vao->buffer);

    *vao = (struct gl_vao){

        .gl = gl,

        .stride = stride,

        .entries = entries,

        .num_entries = num_entries,

    };

    gl->GenBuffers(1, &vao->buffer);

    if (gl->BindVertexArray) {

        gl->BindBuffer(GL_ARRAY_BUFFER, vao->buffer);

        gl->GenVertexArrays(1, &vao->vao);

        gl->BindVertexArray(vao->vao);

        gl_vao_enable_attribs(vao);

        gl->BindVertexArray(0);

        gl->BindBuffer(GL_ARRAY_BUFFER, 0);

    }

}

void gl_vao_uninit(struct gl_vao *vao)

{

    GL *gl = vao->gl;

    if (!gl)

        return;

    if (gl->DeleteVertexArrays)

        gl->DeleteVertexArrays(1, &vao->vao);

    gl->DeleteBuffers(1, &vao->buffer);

    *vao = (struct gl_vao){0};

}

static void gl_vao_bind(struct gl_vao *vao)

{

    GL *gl = vao->gl;

    if (gl->BindVertexArray) {

        gl->BindVertexArray(vao->vao);

    } else {

        gl->BindBuffer(GL_ARRAY_BUFFER, vao->buffer);

        gl_vao_enable_attribs(vao);

        gl->BindBuffer(GL_ARRAY_BUFFER, 0);

    }

}

static void gl_vao_unbind(struct gl_vao *vao)

{

    GL *gl = vao->gl;

    if (gl->BindVertexArray) {

        gl->BindVertexArray(0);

    } else {

        for (int n = 0; n < vao->num_entries; n++)

            gl->DisableVertexAttribArray(n);

    }

}

// Draw the vertex data (as described by the gl_vao_entry entries) in ptr

// to the screen. num is the number of vertices. prim is usually GL_TRIANGLES.

// If ptr is NULL, then skip the upload, and use the data uploaded with the

// previous call.

void gl_vao_draw_data(struct gl_vao *vao, GLenum prim, void *ptr, size_t num)

{

    GL *gl = vao->gl;

    if (ptr) {

        gl->BindBuffer(GL_ARRAY_BUFFER, vao->buffer);

        gl->BufferData(GL_ARRAY_BUFFER, num * vao->stride, ptr, GL_STREAM_DRAW);

        gl->BindBuffer(GL_ARRAY_BUFFER, 0);

    }

    gl_vao_bind(vao);

    gl->DrawArrays(prim, 0, num);

    gl_vao_unbind(vao);

}

static void GLAPIENTRY gl_debug_cb(GLenum source, GLenum type, GLuint id,

                                   GLenum severity, GLsizei length,

                                   const GLchar *message, const void *userParam)

{

    // keep in mind that the debug callback can be asynchronous

    struct mp_log *log = (void *)userParam;

    int level = MSGL_ERR;

    switch (severity) {

    case GL_DEBUG_SEVERITY_NOTIFICATION:level = MSGL_V; break;

    case GL_DEBUG_SEVERITY_LOW:         level = MSGL_INFO; break;

    case GL_DEBUG_SEVERITY_MEDIUM:      level = MSGL_WARN; break;

    case GL_DEBUG_SEVERITY_HIGH:        level = MSGL_ERR; break;

    }

    mp_msg(log, level, "GL: %s\n", message);

}

void gl_set_debug_logger(GL *gl, struct mp_log *log)

{

    if (gl->DebugMessageCallback)

        gl->DebugMessageCallback(log ? gl_debug_cb : NULL, log);

}

// Given a GL combined extension string in extensions, find out whether ext

// is included in it. Basically, a word search.

bool gl_check_extension(const char *extensions, const char *ext)

{

    int len = strlen(ext);

    const char *cur = extensions;

    while (cur) {

        cur = strstr(cur, ext);

        if (!cur)

            break;

        if ((cur == extensions || cur[-1] == ' ') &&

            (cur[len] == '\0' || cur[len] == ' '))

            return true;

        cur += len;

    }

    return false;

}