/**
 * Name:
 *        subDataRemapping.
 * Purpose:
 *        Remaps the 3km fire emission to 9km.
 * Inputs:
 *        - column and row indexes of the 3km and 9km grids.
 *        - 3km grid fire emission.
 *        - 3km grid fire emission quality.
 * Output:
 *        - 9km grid fire emission.
 * Procedure:
 *         Aggregate the fire emission of the 3km grids with valid value and
 *         medium or high quality.
 *
 * @param remappingindexfile The input file that contains column and row indexes
 *        for 3km and 9km grids.
 * @param var3  The input array that contains the 3km grid fire emission.
 * @param qaf   The input array that contains the 3km grid quality.
 * @param var9 The output array that stores the remapped 9km fire emission
 *              types.
 *
 */

int subDataRemapping(char *remappingindexfile, float var3[], short int qaf3[],
                     float var9[])
{
    // Declare variables.
    FILE *fp;
    char buffer[MAX_LEN];
    int i, m;
    long int k;

    int nps, npp;
    char *token;

    int i9, j9; // column index (i9) and row index (j9) for 9km data.
    int i3, j3;   // column index (i3) and row index (j3) for 3km data.

    // Initialize var9.
    for (i = 0; i < LAST_HOURS * grid_xt_9km * grid_yt_9km; i++)
        var13[i] = 0.0;

    // Open the grid index file.
    fp = fopen(remappingindexfile, "r");
    if (fp == NULL)
    {
        perror("Failed: ");
        return 1;
    }
    // To execute a while-loop grid by grid.
    while (fgets(buffer, MAX_LEN, fp)) // read a line from a given grid and stores it a string.
    {
        // Remove trailing newline characters from end of string and replace it
        // with '\0'.
        buffer[strcspn(buffer, "\n")] = 0;

        // Extract 9km grid column and row indexes.
        token = strtok(buffer, ","); // break the string into a series of tokens.
        i9 = atoi(token);

        token = strtok(NULL, ",");
        j9 = grid_yt_9km - 1 - atoi(token);

        m = j9 * LAST_HOURS * grid_xt_9km + i9;

        // Extract the number of 3km grids centered at a given 9km grid.
        token = strtok(NULL, ",");
        nps = atoi(token);

        // Read lats/lons of four angle points for a given 9km grid.
        for (i = 0; i < 4; i++)
            fgets(buffer, MAX_LEN, fp);

        // Initialize.
        npp = 0;

        // Loop execution to get 13km grid emissions.
        for (i = 0; i < nps; i++)
        {
            // Extract 3km grid column and row indexes.
            fgets(buffer, MAX_LEN, fp);
            token = strtok(buffer, ",");
            token = strtok(NULL, ",");

            i3 = atoi(token);
            token = strtok(NULL, ",");

            j3 = atoi(token);
            k = j3 * LAST_HOURS * grid_xt_3km + i3;

            /*
               Aggregate 3km grid emissions for the grid with medium or high
               quality and emission value greater than 0.0.
            */
            if ((qaf3[k] == 2 || qaf3[k] == 3) && var3[k] > 0.0)
            {
                var9[m] = var9[m] + var3[k];
                npp = npp + 1;
            }
        }

        // Assign 9km emissions to  '-1.0' for the grids with low quality or no
        // valid values.
        if (npp == 0)
            var13[m] = -1.0;
    }
   // Close the open file stream.
    fclose(fp);

    return 0;
}