/************************************************************************************\ 
 *                                                                                  *
 * Copyright � 2014 Advanced Micro Devices, Inc.                                    *
 * Copyright (c) 2015 Mark D. Hill and David A. Wood                                *
 * Copyright (c) 2021 Gaurav Jain and Matthew D. Sinclair                           *
 * All rights reserved.                                                             *
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 * provided with the software.                                                      *
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\************************************************************************************/

typedef struct csr_array_t {

    int *row_array;
    int *col_array;
    int *data_array;

    int *row_array_t;
    int *col_array_t;
    int *data_array_t;

} csr_array;


typedef struct cooedgetuple {
    int row;
    int col;
    int val;
} CooTuple;

bool compare(
    CooTuple elem1,
    CooTuple elem2)
{
    if (elem1.row < elem2.row)
        return true;
    return false;
}

void transform(CooTuple *tuple_array, int num_edges, int *row_array, int *col_array, int *data_array)
{

    int row_cnt = 0;
    int prev = -1;
    int idx;

    for (idx = 0; idx < num_edges; idx++) {
        int curr = tuple_array[idx].row;
        if (curr != prev) {
            row_array[row_cnt++] = idx;
            prev = curr;
        }

        col_array[idx]  = tuple_array[idx].col;
        data_array[idx] = tuple_array[idx].val;

    }
    row_array[row_cnt] = idx;
}

csr_array * parseCOO(char* tmpchar, int *p_num_nodes, int *p_num_edges, bool directed)
{
    int cnt = 0;
    int cnt1 = 0;
    unsigned int lineno = 0;
    char sp[2], a, p;
    char * line = (char *)malloc(8192 * sizeof(char));
    int num_nodes = 0, num_edges = 0;

    FILE *fptr;
    CooTuple *tuple_array   = NULL;
    CooTuple *tuple_array_t = NULL;

    fptr = fopen(tmpchar, "r");
    if (!fptr) {
        fprintf(stderr, "Error when opennning file: %s\n", tmpchar);
        perror("ERROR: ");
        exit(1);
    }

    printf("Opening file: %s\n", tmpchar);

    while (fgets(line, 8192, fptr)) {
        int head, tail, weight;
        switch (line[0]) {
        case 'c':
            break;
        case 'p':
            sscanf(line, "%c %s %d %d", &p, sp, p_num_nodes, p_num_edges);

            if (!directed) {
                *p_num_edges = *p_num_edges * 2;
                printf("This is an undirected graph\n");
            } else {
                printf("This is a directed graph\n");
            }

            num_nodes  =  *p_num_nodes;
            num_edges =   *p_num_edges;

            printf("Read from file: num_nodes = %d, num_edges = %d\n", num_nodes, num_edges);

            tuple_array       = (CooTuple *)malloc(sizeof(CooTuple) * num_edges);
            if (!tuple_array) printf("malloc failed\n");
            tuple_array_t     = (CooTuple *)malloc(sizeof(CooTuple) * num_edges);
            if (!tuple_array_t) printf("malloc failed\n");

            break;

        case 'a':
            sscanf(line, "%c %d %d %d", &a, &head, &tail, &weight);

            if (tail == head) printf("reporting self loop\n");

            CooTuple temp, temp1;

            temp.row = head - 1;
            temp.col = tail - 1;
            temp.val = weight;

            temp1.row = tail - 1;
            temp1.col = head - 1;
            temp1.val = weight;

            tuple_array[cnt++]   = temp;
            tuple_array_t[cnt1++] = temp1;

            if (!directed) {

                temp.row = tail - 1;
                temp.col = head - 1;
                temp.val = weight;

                temp1.row = head - 1;
                temp1.col = tail - 1;
                temp1.val = weight;

                tuple_array[cnt++]   = temp;
                tuple_array_t[cnt1++] = temp1;

            }

            break;
        default:
            fprintf(stderr, "exiting loop\n");
            break;
        }
        lineno++;
    }

    std::stable_sort(tuple_array,   tuple_array   + num_edges, compare);
    std::stable_sort(tuple_array_t, tuple_array_t + num_edges, compare);

    int *row_array = (int *)malloc((num_nodes + 1) * sizeof(int));
    int *col_array = (int *)malloc(num_edges * sizeof(int));
    int *data_array = (int *)malloc(num_edges * sizeof(int));

    int *row_array_t = (int *)malloc((num_nodes + 1) * sizeof(int));
    int *col_array_t = (int *)malloc(num_edges * sizeof(int));
    int *data_array_t = (int *)malloc(num_edges * sizeof(int));

    transform(tuple_array,   num_edges, row_array,   col_array, data_array);
    transform(tuple_array_t, num_edges, row_array_t, col_array_t, data_array_t);

    fclose(fptr);
    free(tuple_array);
    free(tuple_array_t);

    csr_array *csr = (csr_array *)malloc(sizeof(csr_array));

    csr -> row_array = row_array;
    csr -> col_array = col_array;
    csr -> data_array = data_array;

    csr -> row_array_t  = row_array_t;
    csr -> col_array_t  = col_array_t;
    csr -> data_array_t = data_array_t;

    free(line);

    return csr;
}