/*
 * This software is licensed under the terms of the MIT-License
 * See COPYING for further information.
 * ---
 * Copyright (C) 2011, Lukas Weber <laochailan@web.de>
 */

#include "model.h"
#include "list.h"
#include "resource.h"
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

static void parse_obj(const char *filename, ObjFileData *data);
static void free_obj(ObjFileData *data);

char* model_path(const char *name) {
	return strjoin(MDL_PATH_PREFIX, name, MDL_EXTENSION, NULL);
}

bool check_model_path(const char *path) {
	return strendswith(path, MDL_EXTENSION);
}

void* load_model(const char *path, unsigned int flags) {
	Model *m = malloc(sizeof(Model));

	ObjFileData data;
	unsigned int i;

	Vertex *verts;
	unsigned int ioffset = _vbo.offset;

	parse_obj(path, &data);

	m->fverts = data.fverts;
	m->indices = calloc(data.icount, sizeof(unsigned int));
	m->icount = data.icount;

	verts = calloc(data.icount, sizeof(Vertex));

#define BADREF(filename,aux,n) { log_warn("OBJ file '%s': Index %d: bad %s index reference\n", filename, n, aux); free(verts); free_obj(&data); return NULL; }

	memset(verts, 0, data.icount*sizeof(Vertex));
	for(i = 0; i < data.icount; i++) {
		int xi, ni, ti;

		xi = data.indices[i][0]-1;
		if(xi < 0 || xi >= data.xcount)
			BADREF(path, "vertex", i);

		memcpy(verts[i].x, data.xs[xi], sizeof(Vector));

		if(data.tcount) {
			ti = data.indices[i][1]-1;
			if(ti < 0 || ti >= data.tcount)
				BADREF(path, "texcoord", i);

			verts[i].s = data.texcoords[ti][0];
			verts[i].t = data.texcoords[ti][1];
		}

		if(data.ncount) {
			ni = data.indices[i][2]-1;
			if(ni < 0 || ni >= data.ncount)
				BADREF(path, "normal", ni);

			memcpy(verts[i].n, data.normals[ni], sizeof(Vector));
		}

		m->indices[i] = i+ioffset;
	}

#undef BADREF

	vbo_add_verts(&_vbo, verts, data.icount);

	free(verts);
	free_obj(&data);

	return m;
}

void unload_model(void *model) { // Does not delete elements from the VBO, so doing this at runtime is leaking VBO space
	free(((Model*)model)->indices);
	free(model);
}

static void free_obj(ObjFileData *data) {
	free(data->xs);
	free(data->normals);
	free(data->texcoords);
	free(data->indices);
}

static void parse_obj(const char *filename, ObjFileData *data) {
	SDL_RWops *rw = SDL_RWFromFile(filename, "r");

	if(!rw) {
		log_warn("SDL_RWFromFile() failed: %s", SDL_GetError());
		return;
	}

	char line[256];
	Vector buf;
	char mode;
	int linen = 0;

	memset(data, 0, sizeof(ObjFileData));

	while(SDL_RWgets(rw, line, sizeof(line))) {
		linen++;

		char *first;
		first = strtok(line, " \n");

		if(strcmp(first, "v") == 0)
			mode = 'v';
		else if(strcmp(first, "vt") == 0)
			mode = 't';
		else if(strcmp(first, "vn") == 0)
			mode = 'n';
		else if(strcmp(first, "f") == 0)
			mode = 'f';
		else
			mode = 0;

		if(mode != 0 && mode != 'f') {
			buf[0] = atof(strtok(NULL, " \n"));
			buf[1] = atof(strtok(NULL, " \n"));
			if(mode != 't')
				buf[2] = atof(strtok(NULL, " \n"));

			switch(mode) {
			case 'v':
				data->xs = realloc(data->xs, sizeof(Vector)*(++data->xcount));
				memcpy(data->xs[data->xcount-1], buf, sizeof(Vector));
				break;
			case 't':
				data->texcoords = realloc(data->texcoords, sizeof(Vector)*(++data->tcount));
				memcpy(data->texcoords[data->tcount-1], buf, sizeof(Vector));
				break;
			case 'n':
				data->normals = realloc(data->normals, sizeof(Vector)*(++data->ncount));
				memcpy(data->normals[data->ncount-1], buf, sizeof(Vector));
				break;
			}
		} else if(mode == 'f') {
			char *segment, *seg;
			int j = 0, jj;
			IVector ibuf;
			memset(ibuf, 0, sizeof(ibuf));

			while((segment = strtok(NULL, " \n"))) {
				seg = segment;
				j++;

				jj = 0;
				while(jj < 3) {
					ibuf[jj] = atoi(seg);
					jj++;

					while(*seg != '\0' && *(++seg) != '/');

					if(*seg == '\0')
						break;
					else
						seg++;
				}

				if(strstr(segment, "//")) {
					ibuf[2] = ibuf[1];
					ibuf[1] = 0;
				}

				if(jj == 0 || jj > 3 || segment[0] == '/')
					log_fatal("OBJ file '%s:%d': Parsing error: Corrupt face definition", filename,linen);

				data->indices = realloc(data->indices, sizeof(IVector)*(++data->icount));
				memcpy(data->indices[data->icount-1], ibuf, sizeof(IVector));
			}

			if(data->fverts == 0)
				data->fverts = j;

			if(data->fverts != j)
				log_fatal("OBJ file '%s:%d': Parsing error: face vertex count must stay the same in the whole file", filename, linen);

			if(data->fverts != 3 && data->fverts != 4)
				log_fatal("OBJ file '%s:%d': Parsing error: face vertex count must be either 3 or 4", filename, linen);
		}
	}

	SDL_RWclose(rw);
}

Model* get_model(const char *name) {
	return get_resource(RES_MODEL, name, RESF_DEFAULT)->model;
}

void draw_model_p(Model *model) {
	GLenum flag = model->fverts == 3 ? GL_TRIANGLES : GL_QUADS;

	glMatrixMode(GL_TEXTURE);
	glScalef(1,-1,1); // every texture in taisei is actually read vertically mirrored. and I noticed that just now.

	glDrawElements(flag, model->icount, GL_UNSIGNED_INT, model->indices);

	glLoadIdentity();
	glMatrixMode(GL_MODELVIEW);
}

void draw_model(const char *name) {
	draw_model_p(get_model(name));
}