/* This program demonstrates:
 * 1. Working with files
 * 2. Working with files and structures
 *
 * * C++ programs can interct with files - read data from files instead fo the keyboard
 * and print data to files instead of the terminal/screen
 * To work with files,
 * 1. Create the file variables - > ifstream for input (cin), ofstream for output (cout)
 * 2. open a file with the file variable -> check if ok
 * 3. Use the file, just like cin/cout
 * 4. close them
 */

#include<iostream>
#include<fstream>
#include<string>
using namespace std;

//Declaring the Movie structure.
struct Movie
{
    string name, director, rating;
    double collect, runtime;
    int year;
};

//Function involving a stream variable - they always pass by reference
void printMovies(ofstream &out, Movie arr[], int num);

int main()
{
    /* To open an input file, that is, a file that contains data we need to
     * read into our program, a la cin, we need a variable of type ifstream
     * Similarly, to open an output file, that contains data that we are
     * producing in the program, we need a variable of type ofstream.
     */
    ifstream input;
    ofstream output;

    input.open ("numbers.txt");  // open the filename given by the user.
    output.open("total.txt");

    if(!input)
    {
        cout<<"Unable to open input file"<<endl;
    }
    else if(!output)
    {
        cout<<"Cannot open the output file"<<endl;
    }
    else
    {
        /* file was opened successfully.
         * We can now use the ifstream variable just like cin, to read from the file
         * We read until we reach the end of the file. The end of the file can be
         * checked using the eof() function. It returns true if we have reached the end
         * of the file
         * This logic is similar to the "read until 0" that we did with cin
         */

        double sum =0, val;

        while(!input.eof())
        {
            input >> val;
            sum = sum + val;
        }
        // Write to the output file instead of the screen. Works like cout
        output << "The sum is "<< sum << endl;
    }

    // once we are done using the file, we have to close the files
    input.close();
    output.close();

    char inName[30], outName[30];

    /* We can read in the filename from the user. If we do this,
    * it has to be a c-string.
    * Since c++ doesn't like file names with spaces, we can just use >>
    * instead of getline
    */
    cout<<"Enter the input file name: ";
    cin>> inName;
    cout<<"Enter the output file name: ";
    cin>> outName;


    /* This  part of the program demonstrates how to read in values from
     * a file into a dynamically allocated array of structures.
     * We create a Movie structure.
     * The first line of the input file is the number of Movie records.
     * Every other line has the following format:
     *     Name # Box Office Collection # Runtime # Year # Director # Rating
     * The # character is used as a separator, to let us know where one element ends and the other begins.
     */

    input.open(inName);
    output.open(outName);
    bool opened = true;     // We can also use this to ensure the files were opened correctly
    if(!input)
    {
        opened = false;
        cout<<"Unable to open input file"<<endl;
    }

    if(!output)
    {
        opened = false;
        cout<<"Unable to open output file"<<endl;
    }
    int numRecord;  // number of records
    Movie *mArray;  // pointer for the dynamic array

    if(opened)
    {
        input >> numRecord;
        mArray = new Movie[numRecord];      //create the dynamic array

        input.ignore();         //gets rid of newline after number

        char pound;              // a char to read the separator character

        for(int i=0; i<numRecord; i++)
        {
            getline(input, mArray[i].name, '#' );
            input >> mArray[i].collect >> pound >> mArray[i].runtime >> pound >> mArray[i].year >> pound;
            getline(input, mArray[i].director, '#');
            getline(input, mArray[i].rating, '\n');
        }

        cout<<"Inputs processed successfully"<<endl;

       // Use the print function to print
        printMovies(output, mArray, numRecord);
    }
    delete [] mArray;
    input.close();
    output.close();

    return 0;
}

/* This function takes a Movie structure array variable, its size and
 * an ofstream variable as parameters
 * We can use this to print data to a particular stream
 * In this case, that stream is the output file.
 * stream variables have to always be passed by reference.
 */
void printMovies(ofstream &out, Movie arr[], int num)
{
    // Just use the oftstream variable like cout.
    for(int i=0; i<num; i++)
    {
        out<< arr[i].name <<" directed by "<< arr[i].director <<" rated "<< arr[i].rating
           <<" was released in "<< arr[i].year<<".\nRuntime: "<< arr[i].runtime
           <<" hours. Box Office Collection: $ "<< arr[i].collect<<" M."<< endl;
    }
}