DBClass.h

#include <iostream>
#include <string>
#include <sqlite3.h>
using namespace std;

class TimeTable {
    private:
    sqlite3 *db;
    char *zErrMsg;
    int rc;
    const char* sql;
    sqlite3_stmt *stmt;
        static int callback(void *NotUsed, int argc, char **argv, char **azColName){
            int i;
            for(i = 0; i<argc; i++){
                printf("%s = %s\n", azColName[i], argv[i] ? argv[1] : "NULL");
            }
            printf("\n");
            return 0;
        }
        void DBErrors() {
            if (rc) {
                cout << "Data Base Error:" << sqlite3_errmsg(db) << endl;
                closeDB();
            }
        }//Returns errors given by SQLite
        //The following section is used to create the tables
        void ModulesTable(){ //To be run after courses table
            sql = "CREATE TABLE Modules("\
                  "MODULE_ID   VARCHAR PRIMARY KEY     NOT NULL,"\
                  "MODULE_NAME TEXT                    NOT NULL,"\
                  "Course      VARCHAR ,"\
                  "FOREIGN KEY (Course) REFERENCES Courses(Course_ID));";
            rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
        }
        void CoursesTable(){  //To be run first in the program
            sql = "CREATE TABLE Courses("\
                  "Course_ID   VARCHAR     PRIMARY KEY     NOT NULL,"\
                  "Course_Name VARCHAR                     NOT NULL);";
            rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
        }
        void ClassesTable(){  //To be run after both the courses table and the modules table
            sql = "CREATE TABLE Classes("\
                  "ID           NOT NULL ,"\
                  "NAME                        NOT NULL ,"\
                  "ROOM                 NOT NULL ,"\
                  "Time             NOT NULL,"\
                  "Location          NOT NULL,"\
                  "Course  ,"\
                  "Lecturer                NOT NULL,"\
                  "Student_ID          NOT NULL,"\
                  "MODULE   NOT NULL);";
            rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
        }
        void StudentsTable(){  // To be run after courses table
            sql = "CREATE TABLE Students("\
                  "STUDENT_ID  INTEGER                 NOT NULL ,"\
                  "STUDENT_NAME    VARCHAR             NOT NULL ,"\
                  "Course   VARCHAR,"\
                  "FOREIGN KEY (Course) REFERENCES Courses(Course_ID));";
            rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
        }
        void ChecksNSubmission(char *query){
            sqlite3_prepare(db, query, strlen(query), &stmt, nullptr);
            rc = sqlite3_step(stmt);
            sqlite3_finalize(stmt);
            free(query);
            DBErrors();
        }//Prepares the sql stmt provided then runs it through SQLite
        //This following section uses placeholders in order to take input and insert it into
        //the relevant tables
        void IntoModules(const char* ID, const char* NOM, const char* CID){ // To Be inserted second after courses
            char *query = nullptr;
            asprintf(&query, "INSERT INTO Modules (MODULE_ID, MODULE_NAME, Course) "
                             "VALUES ('%s','%s', '%s');",ID,NOM,CID);
            ChecksNSubmission(query);
            DBErrors();
        }
        void IntoClasses(const char* ID,const char* NOM,const char* RMNUM,const char* TIM,const char* LOC,
                         const char* MID,const char* CID,const char* LEC,const char* SID){ //To be inserted last
            char *query = nullptr;
            asprintf(&query, "INSERT INTO Classes (ID, NAME, ROOM, Time, Location, MODULE, Course, Lecturer, Student_ID) "
                             "VALUES ('%s','%s','%s','%s','%s','%s','%s','%s','%s');",ID,NOM,RMNUM,TIM,LOC,MID,CID,LEC,SID);
            ChecksNSubmission(query);
            DBErrors();
        }
        void IntoStudents(const char* ID, const char* SN, const char* CS){ //To be run second or after courses table is filled
            char *query = nullptr;
            asprintf(&query, "INSERT INTO Students (STUDENT_ID, STUDENT_NAME, Course) "
                             "VALUES ('%s','%s','%s');",ID,SN,CS);
            ChecksNSubmission(query);
        }
        void IntoCourses(const char* CID, const char* CN){ //To be inserted first
        char *query = nullptr;
        asprintf(&query, "INSERT INTO Courses (Course_ID, Course_Name) "
                         "VALUES ('%s','%s');",CID,CN);
        ChecksNSubmission(query);
    }

public:
        TimeTable(){//This function is to automatically create the tables when initiating
            //This Portion allows user to name the database
            cout<<"What would you like to name the Database? : "<<endl;
            string FileName ;
            cin >> FileName;
            rc = sqlite3_open( FileName.c_str(), &db);
            DBErrors();
            cout<<"Creating Courses Table"<<endl;
            CoursesTable();
            DBErrors();
            cout<<"Creating Modules Table"<<endl;
            ModulesTable();
            DBErrors();
            cout<<"Creating Students Table"<<endl;
            StudentsTable();
            DBErrors();
            cout<<"Creating Classes Table"<<endl;
            ClassesTable();
            DBErrors();
        }
        //The following section has functions that ask the user for the inputs
        //into the tables and then converts those inputs into a format that could
        //be used by the function connected it in the private domain all of them will
        //have something in common and that is that they all convert from input
        //string to const char* which is needed in order to use the pointers set earlier
        void FillModulesTable() {
            int NumM;
            int i = 0;
            cout << "How many modules would you like to add to the record today? "<<endl;
            cin >> NumM;
            while (i != NumM) {
                i++;
                string I_D, N_OM, C_ID;
                cout << "Please enter the module ID number for module number " << i << endl;
                cin >>I_D ;
                cout << "Please enter the name for module number " << i << endl;
                cin >>N_OM ;
                cout << "Please enter the Course ID in which a student would undertake module number " << i << endl;
                cin >>C_ID;
                const char* ID = I_D.c_str();
                const char* NOM = N_OM.c_str();
                const char* CID = C_ID.c_str();
                IntoModules(ID,NOM,CID);
            }
        }
        void FillClassesTable(){
            int NumC;
            int i = 0;
            cout<<"How many classes would you like to add to the record today? "<<endl;
            cin>>NumC;
            while (i != NumC){
                i++;
                string id,nom,rmnum,tim,loc,mid,cid,lec,sid;
                cout<<"Please enter the ID for class number "<<i<<endl;
                cin>>id;
                cout<<"Please enter the name of class number "<<i<<endl;
                cin>>nom;
                cout<<"Please enter the room number for class number "<<i<<endl;
                cin>>rmnum;
                cout<<"Please enter the time for class number "<<i<<endl;
                cin>>tim;
                cout<<"Please enter the module ID for class number "<<i<<endl;
                cin>>mid;
                cout<<"Please enter the course ID for class number "<<i<<endl;
                cin>>cid;
                cout<<"Please enter the lecturer's name for class number "<<i<<endl;
                cin>>lec;
                cout<<"Please enter the student ID to attend class number "<<i<<endl;
                cin>>sid;
                cout<<"Please enter the location of class number "<<i<<endl;
                cin>>loc;
                const char* LOC = loc.c_str();
                const char* ID = id.c_str();
                const char* NOM = nom.c_str();
                const char* RMNUM = rmnum.c_str();
                const char* TIM = tim.c_str();
                const char* MID = mid.c_str();
                const char* CID = cid.c_str();
                const char* LEC = lec.c_str();
                const char* SID = sid.c_str();
                IntoClasses(ID,NOM,RMNUM,TIM,LOC,MID,CID,LEC,SID);
            }

        }
        void FillStudentsTable(){
            int NumS;
            int i = 0;
            cout<<"How many students would you like to add to the record today? "<<endl;
            cin>>NumS;
            while (i != NumS){
                i++;
                string id,sn,cs;
                cout<<"Please enter the ID number for student number "<<i<<endl;
                cin>> id;
                cout<<"Please enter only the name of student number "<<i<<endl;
                cin>> sn;
                cout<<"Please enter the course ID of student number "<<i<<endl;
                cin>> cs;
                const char* ID = id.c_str();
                const char* SN = sn.c_str();
                const char* CS = cs.c_str();
                IntoStudents(ID,SN,CS);
            }

        }
        void FillCoursesTable(){
            int NumC;
            int i = 0;
            cout <<"How many courses would you like to add to the registry today? "<<endl;
            cin>>NumC;
            while (i != NumC){
                i++;
                string cid,cn;
                cout<<"Please enter the course ID for course number "<<i<<endl;
                cin >> cid;
                cout<<"Please enter the course name for course number "<<i<<endl;
                cin >> cn;
                const char* CID = cid.c_str();
                const char* CN = cn.c_str();
                IntoCourses(CID,CN);
            }
        }
        //The following section includes functions that are solely asked to query
        //data from the database and present it
        void EnrolledStudents(){
            sql = "SELECT * FROM Students";
            rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
        }
        void CoursesAvailable(){
            sql = "SELECT * FROM Courses";
            rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
        }
        void ModulesAvailable(){
                sql = "SELECT * FROM Modules";
                rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
            }
        void ClassesAvailable(){
                sql = "SELECT * FROM Classes";
                rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
            }
        void StudentTimeTable(){
            string sid;
            cout<<"Please enter the ID of the student you would like to see the schedule of: "<<endl;
            cin>>sid;
            const char* SID = sid.c_str();
            char *query = nullptr;
            asprintf(&query, "SELECT NAME as Class_Name,"\
                             "Time as Class_Time,"\
                             "Location as Class_Location,"\
                             "MODULE_NAME as M_Name,"\
                             "Lecturer as Class_Lecturer,"\
                             "Course_Name as Course,"\
                             "Classes.Student_ID  as Student_ID,"\
                             "S.STUDENT_NAME as STUDENT_NAME"\
                             "FROM Classes"\
                             "INNER JOIN Modules M on M.MODULE_ID = Classes.MODULE"\
                             "INNER JOIN Courses C on C.Course_ID = M.Course"\
                             "INNER JOIN Students S on S.STUDENT_ID = Classes.Student_ID"\
                             "WHERE Classes.Student_ID = '%s'",SID);
            ChecksNSubmission(query);
        }//This is the most important function as it queries the data
                                    //that is only relevant to a certain student's ID
                                    //in other words it is a certain student's timetable

        void DeleteRow(const char* TableName, const char* ColoumnName, const char* ID){
            char *query = nullptr;
            asprintf(&query, "DELETE FROM ''%s'' WHERE '%s' = '%s';",TableName,ColoumnName,ID);
            ChecksNSubmission(query);
        }
        void closeDB(){
            sqlite3_close(db);
        }
};