#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <stdbool.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include "read.h"

static double st_time;
static double ed_time;

/*
 * -b : bulk read 一括read
 * -d : divide read 分割read (default)
 */
const char *usr_help_str = "Usage : ./read_lseek [-file filename] [-b -d]";
const int ONE_TASK_READ_SIZE = 4096 * 1;
bool bulk_flag = true;
bool divide_flag = false;

void result_printf(int,char *);
void divide_read(int,char*,read_t);
void bulk_read(int,char*,read_t);

static double
get_time(){
    struct timeval tv;
    gettimeofday(&tv,NULL);
    return tv.tv_sec + (double)tv.tv_usec*1e-6;
}

int main(int argc, char *argv[]){

    struct stat sb;
    read_t r;

    char *filename = 0;
    for (int i = 1; argv[i]; ++i) {
        if (strcmp(argv[i], "-file") == 0){
            filename = argv[i+1];
        }else if(strcmp(argv[i], "-b") == 0){
            bulk_flag = true;
            divide_flag = false;
        }else if(strcmp(argv[i], "-d") == 0){
            bulk_flag = false;
            divide_flag = true;
        }
    }

    if (filename == 0){
        puts(usr_help_str);
        exit(1);
    }

    st_time = get_time();

    int fd = -1;
    if ((fd=open(filename,O_RDONLY,0666))==0){
        fprintf(stderr,"can't open %s\n",filename);
    }

    if (fstat(fd,&sb)){
        fprintf(stderr,"can't open %s\n",filename);
    }

    r.text_size = sb.st_size;
    char *text = (char *)malloc(sizeof(char)*r.text_size);

    r.one_task_read_size = ONE_TASK_READ_SIZE;

    r.task_num = r.text_size / r.one_task_read_size;
    r.task_num += ((r.text_size % r.one_task_read_size) != 0);

    if(bulk_flag == true){
        bulk_read(fd,text,r);
    }else if(divide_flag == true){
        divide_read(fd,text,r);
    }

    free(text);
    close(fd);

    ed_time = get_time();
    printf("Time: %0.6f\n",ed_time-st_time);

    return 0;
}

/* lseekで読む場所を指定してあげないといけないと思ったが、
 * readで読み込むだけでも読み込む場所が変わってくれるらしい。
 */
void divide_read(int _fd,char* _text,read_t _r){
    for(int i = 0; i < _r.task_num; i++){
        //lseek(_fd, i * _r.one_task_read_size,SEEK_SET);
        read(_fd,_text,_r.one_task_read_size);
        result_printf(i,_text);
    }
    puts("divide read");
    printf("text size    :%lu\n",_r.text_size);
    printf("one task size:%d\n",_r.one_task_read_size);
    printf("task num     :%d\n",_r.task_num);
}

void bulk_read(int _fd,char* _text,read_t _r){
    int i = 0;
    read(_fd,_text,_r.text_size);
    result_printf(i,_text);
    puts("bulk read");
    printf("text size    :%lu\n",_r.text_size);
}

void result_printf(int _i,char *_text){
    //printf("-------%d--------\n",_i + 1);
    printf("[task No. %d]%s\n",_i,_text);
    //printf("-----------------\n\n");
}