history.h

#include<sstream>
void DISPLAY_HISTORY();
void DISPLAY_HISTORY(int input);
int GET_COUNT();
string to_string(int num)
{
    ostringstream ss;
    ss<<num;
    string n=ss.str();
    return n;
}

string PARSE_COMMAND(string input)
{
    char command[1000];
    int pos=0;
    while((input[pos]>='0' && input[pos]<='9') || input[pos]==' ')
    {
        pos++;
    }
    strcpy(command,&input[pos]);
    string ret(command);
    return ret;
}

string GET_COMMAND(int input)
{
    string command;
    char buff[1000];
    char history_path[1000];
    strcpy(history_path,getenv("HOME"));
    strcat(history_path,"/history.txt");
    char count_path[1000];
    strcpy(count_path,getenv("HOME"));
    strcat(count_path,"/count.txt");
    int count=GET_COUNT();
    FILE *fp=fopen(history_path,"r");
    if(input<0)
    {
        input=input* -1;
        input=(count-input)-1;
        while(input>0)
        {
            fgets(buff, 1000, fp);
            input--;
        }
        fgets(buff, 1000, fp);
        fclose(fp);
        string str(buff);
        return str;   
    }
    else
    {
        while(input>0)
        {
            fgets(buff, 1000, fp);
            input--;
        }
        fclose(fp);
        string str(buff);
        return str;   
    }
}

string GET_COMMAND(string comm)
{
    string command;
    int len=comm.length();
    char buff[1000];
    char history_path[1000];
    strcpy(history_path,getenv("HOME"));
    strcat(history_path,"/history.txt");
    FILE *fp=fopen(history_path,"r");
    while(fgets(buff,1000,fp))
    {
        string temp=PARSE_COMMAND(string(buff));
        string tmp=temp.substr(0,len);
        if(tmp.compare(comm)==0)
        {
            command=string(buff);
        }
    }
    fclose(fp);
    return command;
}

string PARSE_HISTORY_INPUT(string input)
{
    string command;
    char num[100];
    int pos=0;
    while(input[pos]==' ')
    {
        pos++;
    }
    pos++;
    if(input[pos]=='!')
    {
        command=GET_COMMAND(-1);
    }
    else if(input[pos]=='-')
    {
        pos++;
        strcpy(num,&input[pos]);
        command=GET_COMMAND(0-atoi(num));
    }
    else
    {
        strcpy(num,&input[pos]);
        if(num[0]>='a' && num[0]<='z')
        {
            command=GET_COMMAND(string(num));
        }
        else
        {
            command=GET_COMMAND(atoi(num));
            cout<<command<<endl;
        }
    }
    return PARSE_COMMAND(command);

}

void CREATE_HISTORY()
{
    char history_path[1000];
    char count_path[1000];
    strcpy(history_path,getenv("HOME"));
    strcat(history_path,"/history.txt");
    strcpy(count_path,getenv("HOME"));
    strcat(count_path,"/count.txt");
    FILE *fp=fopen(history_path,"a");
    fclose(fp);
    if( access(count_path, F_OK ) == -1 ) 
    {
        fp=fopen(count_path,"w");
        fprintf(fp,"1");
        fclose(fp);
    }
}
void DISPLAY_HISTORY(int input)
{
    char buff[1000];
    char history_path[1000];
    strcpy(history_path,getenv("HOME"));
    strcat(history_path,"/history.txt");
    char count_path[1000];
    strcpy(count_path,getenv("HOME"));
    strcat(count_path,"/count.txt");
    int count=GET_COUNT();
    if(input>=count)
    {
        DISPLAY_HISTORY();   
    }
    else
    {
        FILE *fp=fopen(history_path,"r");
        if(input<0)
        {
            input=input* -1;
            if(input>=count)
            {
                DISPLAY_HISTORY();
            }
            else
            {
                input=count-input+1;
                while(input>0)
                {
                    fgets(buff, 1000, fp);
                    input--;
                }
                while(fgets(buff, 1000, fp)!=NULL)
                {
                    cout<<buff;
                }
                fclose(fp);
            }
        }
        else
        {
            while(input>0)
            {
                fgets(buff, 1000, fp);
                cout<<buff;
                input--;
            }
            fclose(fp);
        }
    }
}
int GET_COUNT()
{
    char count_path[1000];
    strcpy(count_path,getenv("HOME"));
    strcat(count_path,"/count.txt");
    char buff[1000];
    FILE *fp = fopen(count_path, "r");
    fscanf(fp, "%s", buff);
    fclose(fp);
    return atoi(buff);
}

void UPDATE_COUNT()
{
    char count_path[1000];
    strcpy(count_path,getenv("HOME"));
    strcat(count_path,"/count.txt"); 
    char buff[1000];
    FILE *fp = fopen(count_path, "r");
    fscanf(fp, "%s", buff);
    fclose(fp);
    int count=atoi(buff)+1;
    fp = fopen(count_path, "w");
    fprintf(fp,"%s",(to_string(count)).c_str());
    fclose(fp);
}

void RECORD_HISTORY(string input)
{
    if(input.length()!=0)
    {
        char format[1000];
        char history_path[1000];
        strcpy(history_path,getenv("HOME"));
        strcat(history_path,"/history.txt");
        int count=GET_COUNT();
        UPDATE_COUNT();
        strcpy(format,(to_string(count)).c_str());
        strcat(format,"  ");
        strcat(format,input.c_str());
        strcat(format,"\n");
        FILE *fp=fopen(history_path,"a");
        fprintf(fp,"%s",format);
        fclose(fp);
    }
}

void DISPLAY_HISTORY()
{
    char buff[1000];
    char history_path[1000];
    strcpy(history_path,getenv("HOME"));
    strcat(history_path,"/history.txt");
    FILE *fp = fopen(history_path, "r");
    while(fgets(buff, 1000, fp)!=NULL)
    {
        cout<<buff;
    }
}