/*----------------------------------------------------------
 *				HTBLA-Leonding / Class: 2IHIF
 * ---------------------------------------------------------
 * Exercise Number: B1
 * Title:			Mine Sweeper Cell implementation
 * Author:			Marc Tismonar
 * ----------------------------------------------------------
 * Description:
 * Implementation of ms_cell.h.
 * ----------------------------------------------------------
 */

#define CELL_COUNT MAX_BOARD_SIZE * MAX_BOARD_SIZE

#include <stdlib.h>
#include "ms_cell.h"

/** Implementation of cell data */
struct MsCellData {
    CellIdx idx;
    bool covered;
    CellMarker marker;
    bool mine;
    Count dangerous_neighbor_count;
};

/** Maximum amount of cell instances */
static MsCell cells[CELL_COUNT] = {0};

/** The number of produced cells */
static Count produced_cells = 0;

/**
 * Provides another, yet unused instance, initialized Mine Sweeper cell
 * The provided cell is covered, carries no marker, no mine, and has 0 dangerous neighbors.
 * 
 * Up to `MAX_BOARD_SIZE * MAX_BOARD_SIZE` cells can be produced by subsequent
 * calls of this function.
 * 
 * @return The fresh cell instance or 0, if no more instance is available.
 */
MsCell msc_produce_cell() {
    if (produced_cells >= CELL_COUNT) {
        return 0;
    }

    if (cells[produced_cells] == 0) {
        cells[produced_cells] = (MsCell)calloc(1, sizeof(struct MsCellData));
    }

    MsCell cell = cells[produced_cells];
    cell->idx = produced_cells;
    cell->covered = true;
    cell->marker = NONE;
    cell->mine = false;
    cell->dangerous_neighbor_count = 0;

    produced_cells++;
    return cell;
}

/**
 * Resets the internal cell factory. Function `msc_produce_cell` is capable
 * to produce the full number of cell after this function is called.
 */
void msc_reset_cell_factory() {
    produced_cells = 0;
}

/**
 * Determines whether or not the given cell is valid.
 * A cell is NOT valid, if it is 0 or has a neighbor mine count
 * greater than 8.
 * 
 * @param cell The cell instance in focus.
 * @return True if the given cell is valid, false otherwise.
 */
bool msc_is_valid(MsCell cell) {
    return cell != 0 && cell->dangerous_neighbor_count <= 8;
}

/**
 * Determines whether or not the given cell is currently covered.
 * 
 * @param cell The cell instance in focus.
 * @return True if the given cell is covered, false otherwise.
 */
bool msc_is_covered(MsCell cell) {
    return cell != 0 && cell->covered;
}

/**
 * Uncovers the given cell.
 * If the cell carries a veritable marker (detected or suspected)
 * or is already uncovered, the request is ignored. Otherwise 
 * function `msc_is_covered` returns `false` for this cell afterwards.
 * 
 * Note: an uncovered cell cannot be covered again.
 * 
 * @param cell The cell instance in focus.
 * @return True if the cell was successfully uncovered, false otherwise.
 */
bool msc_uncover(MsCell cell) {
    if (!msc_is_valid(cell) || !cell->covered || cell->marker != NONE) {
        return false;
    }

    cell->covered = false;
    return true;
}

/**
 * Determines whether or not the given cell carries a mine.
 * 
 * @param cell The cell instance in focus.
 * @return True if the cell carries a mine, false otherwise.
 */
bool msc_has_mine(MsCell cell) {
    return cell != 0 && cell->mine;
}

/**
 * Specifies that the given cell carries a mine. 
 * Invocations for invalid cells are ignored.
 * 
 * @param cell The cell instance in focus.
 */
void msc_drop_mine(MsCell cell) {
    if (msc_is_valid(cell)) {
        cell->mine = true;
    }
}

/**
 * Provides the number of direct neighbor cells, which carries a mine.
 * 
 * @param cell The cell instance in focus.
 * @return The number between 0 to 8 that encounters the neighbor cells
 * that carries a mine or 255 if the cell is not valid.
 */
Byte msc_get_dangerous_neighbor_count(MsCell cell) {
    return msc_is_valid(cell) ? cell->dangerous_neighbor_count : 0xFF;
}

/**
 * Increments (+1) the count of neighbor cells that carries a mine. 
 * Invocations for invalid cells are ignored.
 * 
 * @param cell The cell instance in focus.
 */
void msc_inc_dangerous_neighbor_count(MsCell cell) {
    if (msc_is_valid(cell)) {
        cell->dangerous_neighbor_count++;
    }
}

/**
 * Provides the given marker of the given cell.
 * 
 * @param cell The cell instance in focus.
 * @return The marker carried by the cell 
 *         or `NONE`, if the cell is not valid.
 */
CellMarker msc_get_marker(MsCell cell) {
    return msc_is_valid(cell) ? cell->marker : NONE;
}

/**
 * Applies the given marker to the given cell. The marker is cleared 
 * by applying a 'none' marker. 
 * Invocations for invalid cells are ignored.
 * 
 * @param cell The cell instance in focus.
 * @param marker The marker to apply.
 */
void msc_set_marker(MsCell cell, CellMarker marker) {
    if (msc_is_valid(cell)) {
        cell->marker = marker;
    }
}