/*
 *   Student: Varun Jain
 *   ID: 260268676
 *   Course: COMP 310
 *   Assignment 2 - KERNEL
 *
 */

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

#define RAM_SIZE 1000
char *RAM[RAM_SIZE];

int RAM_MAX;

struct RAM_STRUCTURE
{
    int freeSpaceSize;
    int zeroPageSize;
} ramFormat;

struct PCB
{
    char filename[50];  // stores the filename of the script loaded into memory
    int start;      // start address – where it is loaded into RAM
    int length;         // the number of instructions
    int current;        // current instruction being executed
    char *heap[20];     // implemented as a list of Shell Memory variables and values
    struct PCB *next;   // next node in the linked-list
} *readyHead, *readyTail, *running, *terminatingHead, *terminatingTail;

struct CPU
{
    int quanta;
    int returnCode;
    int pc; // program counter
    char *memory[20]; // to simulate the CPU registers by copying PCB heap (cell by cell)
};

int myKernel (int argc, char *argv[])
{
    // Step 1: check for kernel specific switches
    int i;

    // Used at a later point
    RAM_MAX = -1;

    // Check through entire string
    for(i = 0; i<argc; i++)
    {
        // If switch -f or -F is present
        if((strncmp(argv[i], "-f", 2) == 0)||(strncmp(argv[i], "-F", 2) == 0))
        {
            // Initialize new string variables
            char newstring[strlen(argv[i])];
            char *result;

            // Copy input into the new string variable
            strcpy(newstring, argv[i]);

            // Tokenize the string, seperated by colons
            result = strtok(newstring, ':');

            // Token position
            int token = 1;

            // While not at third token
            while(token != 3)
            {
                // If at the second token
                if(token == 2)
                {
                    // If the input was less then/equal 1000 and greater then 0,
                    if(result <= RAM_SIZE && result > 0)
                    {
                        RAM_MAX = result;
                    }
                }
                // Grab next value
                result = strtok( NULL,  ':' );
                token++;
            }
        }
    }

    // Step 2: format RAM (since it was already initialized by boot-strap to nulls)

    ramFormat.zeroPageSize = 10;
    if(RAM_MAX =! -1)
    {
        ramFormat.freeSpaceSize = RAM_MAX;
    }
    else
    {
        ramFormat.freeSpaceSize = RAM_SIZE-10;
    }

    /* Step 3: initialize run-time environment
    readyHead = NULL;
    readyTail = readyhead;
    running = NULL;
    terminatingHead = NULL;
    terminatingTail = terminatingHead;

    // Create struct CPU as cpu
    struct CPU cpu;
    CPU->quanta = 0;
    CPU->returnCode = 0;
    CPU->pc = 0;
    cpu.quanta = 0;
    cpu.returnCode = 0;
    cpu.pc = 0;

    // Set memory to null
    for(i=0;i<20;i++)
    {
        cpu.memory[i] = NULL;
    }
    */
    // Step 4: start run-time environment with login screen and later shell

    while (!login());

    /*while (returnCode != -1)
    {
        returnCode = shell(); // returns -1 when user inputs EXIT or LOGOUT
        // OS Overhead – Process execution
        Running = NextReadyQueue();
        TaskSwitchIn(Running);
        SetQuanta(int);
        RunForQuanta();
        TaskSwitchOut(Running); // task switch back
        // OS Overhead – Services
        TerminateProcesses();
    }*/
}

int login(void)
{
    char username[25];
    char password[25];

    // Get login credentials
    printf("=~=~=~=~=~=~==~=~=~=~=~=~==~=~=\n");
    printf("=~=~=~=~=~=  LOGIN  =~=~=~=~=~=\n");
    printf("=~=~=~=~=~=~==~=~=~=~=~=~==~=~=\n\n");
    printf("Username:\n");
    scanf("%s", username);
    printf("Password:\n");
    scanf("%s", password);

    // Read CSV
    FILE *input;
    input = fopen("pass.csv", "r+");

    char f_content[51];
    char *f_token;

    if (input == NULL)
    {
        fclose(input);
        printf("ERROR OPENING PASSWORD FILE");
        return -1;
    }

    while(!feof(input))
    {
        getline(&f_content, 51, input);
        f_token = strtok(f_content, ",");
        if(strcmp(f_token,username)==0)
        {
            f_token = strtok(NULL, ",");
            if(strcmp(f_token,password)==0)
            {
                return 1;
            }
        }
    }
    return 0;
}

int main(void)
{
    char *a[] = {"Hello World", "-f:123", "UP"};
    myKernel(3, a );

    printf("%d\n", login());
    printf("ABOVE IS THE RESULT OF LOGIN");

    /*
    struct PCB *P1 = NULL;
    P1 = (struct PCB*) malloc(sizeof(struct PCB));

    struct PCB *P2 = NULL;
    P2 = (struct PCB*) malloc(sizeof(struct PCB));

    struct PCB *P3 = NULL;
    P3 = (struct PCB*) malloc(sizeof(struct PCB));

    sscanf("FILE_1", "%s", P1->filename);
    sscanf("FILE_2", "%s", P2->filename);
    sscanf("FILE_3", "%s", P3->filename);

    PushReadyQueue(P1);
    PushReadyQueue(P2);
    PushReadyQueue(P3);

    printf("Head is: %s\n", readyHead->filename);
    printf("Middle is: %s\n", readyHead->next->filename);
    printf("Tail is: %s\n\n", readyTail->filename);

    NextReadyQueue();

    printf("RUNNING: %s\n", running->filename);


    PushTerminateQueue(P2);

    printf("Head is: %s\n", readyHead->filename);
    printf("Middle is: %s\n", readyHead->next->filename);
    printf("Tail is: %s\n\n", readyTail->filename);

    PushTerminateQueue(P1);

    printf("Head is: %s\n", readyHead->filename);
    printf("Middle is: %s\n", readyHead->next->filename);
    printf("Tail is: %s\n\n", readyTail->filename);

    printf("RUNNING: %s\n", running->filename);

    printf("Head of DELETE is: %s\n", terminatingHead->filename);
    printf("Middle of DELETE is: %s\n", terminatingHead->next->filename);
    printf("Tail of DELETE is: %s\n\n", terminatingTail->filename);

    PushTerminateQueue(P3);

    printf("Head is: ");
    printf("%d",(readyHead == NULL));
    printf("\nMiddle is: ");

    printf("\nTail is: ");
    printf("%d", (readyTail == NULL));

    printf("\nRUNNING: ");
    printf("%d", (running == NULL));

    printf("\nHead of DELETE is: %s\n", terminatingHead->filename);
    printf("Middle of DELETE is: %s\n", terminatingHead->next->filename);
    printf("Tail of DELETE is: %s\n", terminatingTail->filename);


    /*
    NextReadyQueue();
    NextReadyQueue();

    printf("Current is now: %d AFTER two\n", running->start);

    printf("Head is: %d\n", readyHead->start);
    printf("Middle is: %d\n", readyHead->next->start);
    printf("Tail is: %d\n\n", readyTail->start);

    NextReadyQueue();

    printf("Current is now: %d AFTER three\n", running->start);

    printf("Head is: %d\n", readyHead->start);
    printf("Middle is: %d\n", readyHead->next->start);
    printf("Tail is: %d\n\n", readyTail->start);

    NextReadyQueue();

    printf("Current is now: %d AFTER four\n", running->start);

    struct PCB *Running = running;
    printf("RUNNING is now: %d AFTER four\n", Running->start);
    printf("THE NEXT ONE IS: %d", Running->next->start);
    */


    return 0;

}