/* 
 * This file is part of the Minecraft Overviewer.
 *
 * Minecraft Overviewer 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 3 of the License, or (at
 * your option) any later version.
 *
 * Minecraft Overviewer 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.
 *
 * You should have received a copy of the GNU General Public License along
 * with the Overviewer.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "../overviewer.h"

typedef struct {
    unsigned int mode; /* 0 = exposed only, 1 = unexposed only */
} PrimitiveExposed;

static int
exposed_start(void *data, RenderState *state, PyObject *support) {
    PrimitiveExposed *self = (PrimitiveExposed *)data;
    
    if (!render_mode_parse_option(support, "mode", "I", &(self->mode)))
        return 1;
        
    return 0;
}

static int
exposed_hidden(void *data, RenderState *state, int x, int y, int z) {
    PrimitiveExposed *self = (PrimitiveExposed *)data;
    
    /* Unset these flags if seeming exposure from any of these directions would
     * be due to not having data there.
     */
    int validMinusX = 1;
    int validPlusX = 1;
    int validMinusY = 1;
    int validPlusY = 1;
    int validMinusZ = 1;
    int validPlusZ = 1;

    /* special handling for section boundaries */
    /* If the neighboring section has no block data, ignore exposure from that
     * direction 
     */
    if (x == 0 && (!(state->chunks[0][1].loaded) || state->chunks[0][1].sections[state->chunky].blocks == NULL)) {
        /* No data in -x direction */
        validMinusX = 0;
    }
    
    if (x == 15 && (!(state->chunks[2][1].loaded) || state->chunks[2][1].sections[state->chunky].blocks == NULL)) {
        /* No data in +x direction */
        validPlusX = 0;
    }
    
    if (y == 0 && (state->chunky - 1 < 0 || state->chunks[1][1].sections[state->chunky - 1].blocks == NULL)) {
        /* No data in -y direction */
        validMinusY = 0;
    }
        
    if (y == 15 && (state->chunky + 1 >= SECTIONS_PER_CHUNK || state->chunks[1][1].sections[state->chunky + 1].blocks == NULL)) {
        /* No data in +y direction */
        validPlusY = 0;
    }
    
    if (z == 0 && (!(state->chunks[1][0].loaded) || state->chunks[1][0].sections[state->chunky].blocks == NULL)) {
        /* No data in -z direction */
        validMinusZ = 0;
    }
    
    if (z == 15 && (!(state->chunks[1][2].loaded) || state->chunks[1][2].sections[state->chunky].blocks == NULL)) {
        /* No data in +z direction */
        validPlusZ = 0;
    }
    
    /* If any of the 6 blocks adjacent to us are transparent, we're exposed */
    if( (validMinusX && is_transparent(get_data(state, BLOCKS, x-1, y, z))) ||
        (validPlusX && is_transparent(get_data(state, BLOCKS, x+1, y, z)))  ||
        (validMinusY && is_transparent(get_data(state, BLOCKS, x, y-1, z))) ||
        (validPlusY && is_transparent(get_data(state, BLOCKS, x, y+1, z)))  ||
        (validMinusZ && is_transparent(get_data(state, BLOCKS, x, y, z-1))) ||
        (validPlusZ && is_transparent(get_data(state, BLOCKS, x, y, z+1 ))) ) {
    
        /* Block is exposed */
        /* Returns 1 and hides us if we're rendering unexposed blocks, 0 and 
         * shows us if we're rendering exposed blocks 
         */
        return self->mode; 
    
    }
    
    /* We have no valid evidence that the block is exposed */ 
    return !(self->mode); /* Hide in normal mode, reveal in inverted mode */
}

RenderPrimitiveInterface primitive_exposed = {
    "exposed", sizeof(PrimitiveExposed),
    exposed_start,
    NULL,
    NULL,
    exposed_hidden,
    NULL,
};