/**

  * $Id$

  *

  * Tool to take an input .glsl file and write out a corresponding .c and .h

  * file based on the content. The .glsl file contains a number of shaders

  * marked with either #fragment <name> or #vertex <name>

  * a C file with appropriate escaping, as well as program definitions

  * written as #program <name> = <shader1> <shader2> ... <shaderN>

  *

  * Copyright (c) 2007-2010 Nathan Keynes.

  *

  * This program is free software; you can redistribute it and/or modify

  * it under the terms of the GNU General Public License as published by

  * the Free Software Foundation; either version 2 of the License, or

  * (at your option) any later version.

  *

  * This program 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 General Public License for more details.

  */

 #include <assert.h>

 #include <errno.h>

 #include <stdio.h>

 #include <stdlib.h>

 #include <string.h>

 #include <glib/gstrfuncs.h>

 #include <glib/glist.h>

 #define MAX_LINE 4096

 #define DEF_ALLOC_SIZE 4096

 #define MAX_SHADERS 128

 typedef enum {

     VERTEX_SHADER = 0,

     FRAGMENT_SHADER = 1

 } shader_type_t;

 typedef struct shader {

     shader_type_t type;

     const char *name;

     char *body;

 } *shader_t;

 typedef struct program {

     const char *name;

     gchar **shader_names;

 } *program_t;

 typedef struct glsldata {

     const char *filename;

     unsigned max_shaders;

     GList *shaders;

     GList *programs;

 } *glsldata_t;

 static struct glsldata *readInput( const char *filename )

 {

     char buf[MAX_LINE];

     size_t current_size = 0, current_posn = 0;

     unsigned i;

     FILE *f = fopen( filename, "ro" );

     if( f == NULL ) {

         fprintf( stderr, "Error: unable to open input file '%s': %s\n", filename, strerror(errno) );

         exit(1);

     }

     shader_t shader = NULL;

     glsldata_t result = malloc(sizeof(struct glsldata));

     assert( result != NULL );

     result->filename = strdup(filename);

     result->shaders = NULL;

     result->programs = NULL;

     result->max_shaders = 0;

     while( fgets(buf, sizeof(buf), f) != NULL ) {

         if( strlen(buf) == 0 )

             continue;

         if( strncmp(buf, "#vertex ", 8) == 0 ) {

             shader = malloc(sizeof(struct shader));

             assert( shader != NULL );

             shader->type = VERTEX_SHADER;

             shader->name = strdup(g_strstrip(buf+8));

             shader->body = malloc(DEF_ALLOC_SIZE);

             shader->body[0] = '\0';

             current_size = DEF_ALLOC_SIZE;

             current_posn = 0;

             result->shaders = g_list_append(result->shaders, shader);

         } else if( strncmp( buf, "#fragment ", 10 ) == 0 ) {

             shader = malloc(sizeof(struct shader));

             assert( shader != NULL );

             shader->type = FRAGMENT_SHADER;

             shader->name = strdup(g_strstrip(buf+10));

             shader->body = malloc(DEF_ALLOC_SIZE);

             shader->body[0] = '\0';

             current_size = DEF_ALLOC_SIZE;

             current_posn = 0;

             result->shaders = g_list_append(result->shaders, shader);

         } else if( strncmp( buf, "#program ", 9 ) == 0 ) {

             shader = NULL;

             program_t program = malloc(sizeof(struct program));

             char *rest = buf+9;

             char *equals = strchr(rest, '=');

             if( equals == NULL ) {

                 fprintf( stderr, "Error: invalid program line %s\n", buf );

                 exit(2);

             }

             *equals = '\0';

             program->name = g_strdup(g_strstrip(rest));

             program->shader_names = g_strsplit_set(g_strstrip(equals+1), " \t\r,", 0);

             result->programs = g_list_append(result->programs, program);

             for(i=0;program->shader_names[i] != NULL; i++ );

             if( i > result->max_shaders )

                 result->max_shaders = i;

         } else if( shader != NULL ) {

             size_t len = strlen(buf);

             if( current_posn + len > current_size ) {

                 shader->body = realloc(shader->body, current_size*2);

                 assert( shader->body != NULL );

                 current_size *= 2;

             }

             strcpy( shader->body + current_posn, buf );

             current_posn += len;

         }

     }

     fclose(f);

     return result;

 }

 /**

  * Copy input to output, quoting " characters as we go.

  */

 static void writeCString( FILE *out, const char *str )

 {

     const char *p = str;

     while( *p != 0 ) {

         if( *p == '\"' ) {

             fputc( '\\', out );

         } else if( *p == '\n' ) {

             fputs( "\\n\\", out );

         }

         fputc( *p, out );

         p++;

     }

 }

 static void writeHeader( FILE *out, glsldata_t data )

 {

     fprintf( out, "/*\n * This file automatically generated by genglsl from %s\n */\n", data->filename );

 }

 static void writeInterface( const char *filename, glsldata_t data )

 {

     FILE *f = fopen(filename, "wo");

     if( f == NULL ) {

         fprintf( stderr, "Error: Unable to write interface file '%s': %s\n", filename, strerror(errno) );

         exit(1);

     }

     writeHeader( f, data );

     fprintf( f, "#ifndef lxdream_glsl_H\n#define lxdream_glsl_H 1\n\n" );

     fprintf( f, "typedef enum {\n" );

     const char *last_name = NULL;

     int count = 0;

     GList *shader_ptr;

     for( shader_ptr = data->shaders; shader_ptr != NULL; shader_ptr = shader_ptr->next ) {

         count++;

         shader_t shader = (shader_t)shader_ptr->data;

         fprintf( f, "    %s,\n", shader->name );

         last_name = shader->name;

     }

     fprintf( f, "} shader_id;\n\n" );

     if( last_name == NULL )

         last_name = "NULL";

     fprintf( f, "#define GLSL_LAST_SHADER %s\n", last_name );

     fprintf( f, "#define GLSL_NUM_SHADERS %d\n", count );

     fprintf( f, "#define GLSL_NO_SHADER -1\n\n" );

     fprintf( f, "#define GLSL_VERTEX_SHADER 1\n" );

     fprintf( f, "#define GLSL_FRAGMENT_SHADER 2\n" );

     fprintf( f, "typedef enum {\n" );

     last_name = NULL;

     count = 0;

     GList *program_ptr;

     for( program_ptr = data->programs; program_ptr != NULL; program_ptr = program_ptr->next ) {

         count++;

         program_t program = (program_t)program_ptr->data;

         fprintf( f, "    %s,\n", program->name );

         last_name = program->name;

     }

     fprintf( f, "} program_id;\n\n" );

     if( last_name == NULL )

         last_name = "NULL";

     fprintf( f, "#define GLSL_LAST_PROGRAM %s\n", last_name );

     fprintf( f, "#define GLSL_NUM_PROGRAMS %d\n", count );

     fprintf( f, "#define GLSL_NO_PROGRAM -1\n\n" );

     fprintf( f, "int glsl_load_programs();\n" );

     fprintf( f, "void glsl_use_program_id( program_id );\n" );

     fprintf( f, "#endif /* !lxdream_glsl_H */\n" );

     fclose(f);

 }

 static void writeSource( const char *filename, glsldata_t data )

 {

     FILE *f = fopen(filename, "wo");

     if( f == NULL ) {

         fprintf( stderr, "Error: Unable to write interface file '%s': %s\n", filename, strerror(errno) );

         exit(1);

     }

     writeHeader( f, data );

     fprintf( f, "struct shader_def {\n    int type;\n    const char *source;\n};\n" );

     fprintf( f, "const struct shader_def shader_source[] = {\n" );

     GList *shader_ptr;

     for( shader_ptr = data->shaders; shader_ptr != NULL; shader_ptr = shader_ptr->next ) {

         shader_t shader = (shader_t)shader_ptr->data;

         fprintf( f, "    {%s,\"", (shader->type == VERTEX_SHADER ? "GLSL_VERTEX_SHADER" : "GLSL_FRAGMENT_SHADER") );

         writeCString( f, shader->body );

         fprintf( f, "\"},\n" );

     }

     fprintf( f, "    {GLSL_NO_SHADER,NULL}};\n\n" );

     fprintf( f, "const int program_list[][%d] = {\n", data->max_shaders+1 );

     GList *program_ptr;

     unsigned i;

     for( program_ptr = data->programs; program_ptr != NULL; program_ptr = program_ptr->next ) {

         program_t program = (program_t)program_ptr->data;

         fprintf( f, "    {" );

         for( i=0; program->shader_names[i] != NULL; i++ ) {

             fprintf(f, "%s,", program->shader_names[i] );

         }

         fprintf( f, "GLSL_NO_SHADER},\n" );

     }

     fprintf( f, "    {GLSL_NO_SHADER}};\n" );

     fclose(f);

 }

 const char *makeExtension(const char *basename, const char *ext)

 {

     const char *oldext = strrchr(basename, '.');

     if( oldext == NULL ) {

         return g_strdup_printf("%s%s", basename, ext);

     } else {

         return g_strdup_printf("%.*s%s", (int)(oldext-basename), basename, ext);

     }

 }

 int main( int argc, char *argv[] )

 {

     if( argc < 2 ) {

         fprintf( stderr, "Usage: genglsl <glsl-source-file> [output.c [output.h]]\n");

         exit(1);

     }

     glsldata_t data = readInput(argv[1]);

     const char *sourcefile, *ifacefile;

     if( argc > 2 ) {

         sourcefile = argv[2];

     } else {

         sourcefile = makeExtension(argv[1], ".def");

     }

     if( argc > 3 ) {

         ifacefile = argv[3];

     } else {

         ifacefile = makeExtension(sourcefile, ".h");

     }

     writeSource( sourcefile, data );

     writeInterface( ifacefile, data );

     return 0;

 }