#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#define LOOKUP_FILE_ROWS (400 * 1024 * 1024)
#define LOOKUP_FILE_NAME "lookup_test.csv"

#define LOOKUP_LINE_SIZE 1024


/**
 * This macro represents an inlined, identical portion of code used to time any function.
 * This is such that different abstractions of timings are not affected by function call overhead.
 */

 #define TIMING_FUNCTION_CODE(fn, result) do { \
    clock_t start, end; \
    start = clock(); \
    (fn)(); \
    end = clock(); \
    (result) = ((double) (end - start)) / CLOCKS_PER_SEC; \
    } while(0)

static void make_csv_test(void)
{
    FILE* fp;
    size_t i;
    fp = fopen(LOOKUP_FILE_NAME, "w");
    if(fp == NULL) {
        fprintf(stderr, "Cannot open file %s, exiting\n", LOOKUP_FILE_NAME);
        exit(2);
    }
    for(i = 0 ; i < LOOKUP_FILE_ROWS; i++) {
        fprintf(fp, "%d,%d,%d\n", 1333003, 1234280, 1122040);
    }
    fclose(fp);
}

static void read_and_count_csv_rows(void)
{
    FILE* fp;
    const char* line_reader;
    char* field_writer;
    size_t fields_counted;
    char line_buf[LOOKUP_LINE_SIZE];
    char field_buf[64];
    fields_counted = 0;
    // safe zero'd memory
    memset(line_buf, 0, sizeof(line_buf));
    memset(field_buf, 0, sizeof(field_buf));
    fp = fopen(LOOKUP_FILE_NAME, "r");
    if(fp == NULL) {
        fprintf(stderr, "Cannot open file %s, exiting\n", LOOKUP_FILE_NAME);
        exit(2);
    }
    while(!feof(fp)) {
        size_t field_written = 0;
        fgets(line_buf, LOOKUP_LINE_SIZE, fp);
        line_reader = line_buf;
        field_writer = field_buf;
        while((field_written < sizeof(field_buf)) && *line_reader != ',') {
            *field_writer++ = *line_reader++;
            field_written++;
        }
        fields_counted++;
    }
    fclose(fp);
}

int main(void) {
  double time_taken = 0.0;
  puts("-- Creating csv lookup test file --");
  make_csv_test();
  puts("-- finished creating csv lookup test file --");
  printf(" -- the test will read %lu rows from %s\n", LOOKUP_FILE_ROWS, LOOKUP_FILE_NAME);
  puts("-- starting timed lookup test --");
  TIMING_FUNCTION_CODE(read_and_count_csv_rows, time_taken);
  printf("The lookup csv test took %f seconds\n", time_taken);
  remove(LOOKUP_FILE_NAME);
  return 0;
}