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

int size = 0;

// Mail structure to store each e-mail's information
struct mail {
    int timeindex;
    char month[4];
    int date;
    char *email;
    int msgsize;
    char *subject;
};

// Prints out e-mails in order currently stored in pointer 
void print(struct mail * m1)
{
    int i;
    for(i = 0; i < size; i++)
    {
	printf("%3d ", i + 1);
	printf("%s ", (m1 + i) -> month);
	printf("%d ", (m1 + i) -> date);
	printf("%s ", (m1 + i) -> email);
	printf("%d ", (m1 + i) -> msgsize);
	printf("%s\n", (m1 + i) -> subject);
    }
}

// Sorts emails in ascending order by received time, sender, or message size
void sort(struct mail * m1)
{
    int choice, i, pos;
    struct mail key;

    printf("***Sort Menu***\n");
    printf("1. Sort by received time\n");
    printf("2. Sort by sender\n");
    printf("3. Sort by size\n");

    // Read in user choice
    do {
	printf("Please enter your choice (1-3): ");
	scanf("%d", &choice);
    } while(choice < 1 || choice > 3);

    // Sort in ascending order by time message was received
    if(choice == 1)
    {
	for(i = 0; i < size; i++)
	{
	    for(pos = i; pos < size; pos++)
	    {
		if((m1 + i) -> timeindex > (m1 + pos) -> timeindex)
		{
		    key = *(m1 + i);
		    *(m1 + i) = *(m1 + pos);
		    *(m1 + pos) = key;
		}
	    }
	} 
    }

    // Sort alphabetically by sender e-mail 
    else if(choice == 2)
    {
	for(i = 0; i < size; i++)
	{
	    for(pos = 0; pos < size; i++)
	    {
		if(strcmp((m1 + i) -> email, (m1 + pos) -> email) > 0)
		{
		    key = *(m1 + i);
		    *(m1 + i) = *(m1 + pos);
		    *(m1 + pos) = key;
		}
	    }
	}

    }

    // Sort in ascending order by message size
    else if(choice == 3)
    {
	for(i = 0; i < size; i++)
	{
	    for(pos = i; pos < size; pos++);
	    {
		if((m1 + i) -> msgsize > (m1 + pos) -> msgsize)
		{
		    key = *(m1 + i);
		    *(m1 + i) = *(m1 + pos);
		    *(m1 + pos) = key;
		}
	    }
	}
    }
}

void add(struct mail * m1)
{
    int i, space, check = 0;
    int dtemp, stemp;
    char ch, mtemp[4];
    char *sendtemp = malloc(20 * sizeof(char));
    char *subtemp = malloc(300 * sizeof(char));
    struct mail * m1temp;

    // Read in month (must be legal three-letter abbreviation)
    do {
	printf("the month the message is received (format: mmm): ");
	scanf("%s", mtemp);
    } while(strcmp(mtemp, "Jan") != 0 && strcmp(mtemp, "Feb") != 0 && 
	    strcmp(mtemp, "Mar") != 0 && strcmp(mtemp, "Apr") != 0 && 
	    strcmp(mtemp, "May") != 0 && strcmp(mtemp, "Jun") != 0 && 
	    strcmp(mtemp, "Jul") != 0 && strcmp(mtemp, "Aug") != 0 && 
	    strcmp(mtemp, "Sep") != 0 && strcmp(mtemp, "Oct") != 0 && 
	    strcmp(mtemp, "Nov") != 0 && strcmp(mtemp, "Dec") != 0);

    // Read in date (must be 1 through 31)
    do {
	printf("the day the message is received (format: d or dd): ");
	scanf("%d", &dtemp);
    } while(dtemp < 1 || dtemp > 31);

    // Read in size of message (must be positive integer)
    do {
	printf("the size of the message (format: integer): ");
	scanf("%d", &stemp);
    } while(stemp < 0);

    // Read in sender e-mail (must be single string, no spaces)
    do {
	space = 0;
	printf("the sender of the message (format: no spacing): ");
	scanf("%s", sendtemp);

        // Check to make sure entry is only one string
	while(getchar() != '\n')
	    space++;
    } while(space > 0);

    // Read in subject title character by character into a pointer string
    i = 0;
    printf("the subject of the message (format: no restriction): ");
    ch = getchar();
    while(ch != '\n')
    {
	*(subtemp + i) = ch;
	i++;
	ch = getchar();
    }

    // Check to make sure entry is not identical to another entry in database
    for(i = 0; i < size; i++)
    {
	if(strcmp(mtemp, (m1 + i) -> month) == 0 && 
	   dtemp == (m1 + i) -> date && 
	   stemp == (m1 + i) -> msgsize && 
	   strcmp(sendtemp, (m1 + i) -> email) == 0 && 
	   strcmp(subtemp, (m1 + i) -> subject) == 0)
	    check = 1;
    }

    // If entry is not identical, add to end of database and update size
    if(check == 0)
    {
	m1 = (struct mail *) realloc(m1, (size + 1) * sizeof(m1temp));
	(m1 + size) -> timeindex = size + 1;
	for(i = 0; i < 4; i++)
	    (m1 + size) -> month[i] = mtemp[i];
	(m1 + size) -> date = dtemp;
	(m1 + size) -> msgsize = stemp;
	(m1 + size) -> email = sendtemp;
	(m1 + size) -> subject = subtemp;
	size++;
	printf("The message has been added successfully.\n");
    }
    // If entry already in database, print out failure message
    else
	printf("Message add fails. The message exists in the database.\n");
}

void delete(struct mail * m1)
{
    int i, index;
    // Read in index for deletion
    do {
        printf("Enter the index of the message to delete (1 to %d): ", 
	       size);
        scanf("%d", &index);
    } while(index < 1 || index > size);

    // Shift all entries after index to the left by one
    for(i = index - 1; i < size - 1; i++)
	*(m1 + i) = *(m1 + i + 1);

    // Free last memory location and update size
    free(m1 + size - 1);
    size--;

    printf("Message has been deleted successfully. ");
    printf("There are %d messages left.\n", size);
}

void search(struct mail * m1)
{
    char *s1;
    int i, k, check, count = 0;
    printf("Enter the keyword that you want to search: ");
    scanf("%s", s1);

    // Loop through entire e-mail database pointer array    
    for(i = 0; i < size; i++)
    {
	check = 0;
	k = 0;

        // While current entry's subject is not at end of string, compare each
        // individual word to the keyword
	while((m1 + i) -> subject[k] != '\0')
	{
	    int j = 0;
            // Increment indices while characters in both strings are equal 
            // and not at end of subject string
	    while(s1[j] == (m1 + i) -> subject[k] && 
		  (m1 + i) -> subject[k] != '\0')
	    {
		j++;
		k++;
	    }

            // If length of keyword is equal to j (all characters of word 
            // match) and it is the end of the currently checked word in 
            // entry's subject string, increment check
	    if(strlen(s1) == j && ((m1 + i) -> subject[k] == ' ' || 
				   (m1 + i) -> subject[k] == '\0'))
		check++;

            // Increment subject index until beginning of next word in string
	    while((m1 + i) -> subject[k] != ' ' && 
		  (m1 + i) -> subject[k] != '\0')
		k++;
	    if((m1 + i) -> subject[k] == ' ')
		k++;
	}

        // If check is larger than 1, print out entry keyword was in
	if(check > 0)
	{
	    printf("%3d ", i + 1);
	    printf("%s ", (m1 + i) -> month);
	    printf("%d ", (m1 + i) -> date);
	    printf("%s ", (m1 + i) -> email);
	    printf("%d ", (m1 + i) -> msgsize);
	    printf("%s\n", (m1 + i) -> subject);
	    count++;
	}
    }

    // If keyword not found in any entries, print out keyword not found
    if(count == 0)
	printf("Keyword %s not found.\n", s1);
}

// Print leave message and exit out of program
void leave()
{
    printf("Thanks for using the ENEE 114 Email Database.\n");
    printf("Goodbye!\n");
    exit(0);
}

int main(int argc, char *argv[])
{
    int i, choice;
    char ch, temp;
    FILE *input;
    struct mail *m1, m2;

    // Allocate dynamic memory for mail pointer array
    m1 = (struct mail *) malloc(sizeof(m2));

    // If not enough arguments in command line, print out error
    if(argc != 2)
    {
	printf("Usage: executable input_file\n");
	exit(0);
    }

    input = fopen(argv[1], "r");

    // Check to make sure input file opened correctly
    if(input == NULL)
    {
	printf("File %s cannot open!\n", argv[1]);
	exit(0);
    }

    // Store input file e-mail information into mail database pointer array
    while(fscanf(input, "%c", &temp) != EOF)
    {
	i = 0;

        // Store time index to indicate when message was added
	(m1 + size) -> timeindex = size + 1;

        // Store month abbreviation in character by character
	(m1 + size) -> month[0] = temp;
	fscanf(input, "%c", &((m1 + size) -> month[1]));
	fscanf(input, "%c", &((m1 + size) -> month[2]));
	(m1 + size) -> month[3] = '\0';

        // Store date in
	fscanf(input, "%d", &((m1 + size) -> date));

        // Allocate memory for e-mail string and store string
	(m1 + size) -> email = malloc(20 * sizeof(char));
	fscanf(input, "%s", (m1 + size) -> email);

        // Store message size in
	fscanf(input, "%d", &((m1 + size) -> msgsize));

        // Skip blank space
	fscanf(input, "%c", &ch);

        // Allocate memory for subject string and store in character by 
        // character until at end of current line
	(m1 + size) -> subject = malloc(300 * sizeof(char));
	while(fscanf(input, "%c", &ch) != EOF && ch != '\n')
	{
	    *((m1 + size) -> subject + i) = ch;
	    i++;
	}

        // Update size and reallocate mail pointer to larger memory location
	size++;
	m1 = (struct mail *) realloc(m1, (size + 1) * sizeof(m2));
    }

    // Display menu and call appropriate function for entered choice
    printf("Welcome to ENEE 114 Email Database\n");
    do {
        printf("***Main Menu***\n");
        printf("1. Print\n");
        printf("2. Sort\n");
        printf("3. Add Message\n");
        printf("4. Delete Message\n");
        printf("5. Keyword Search\n");
        printf("6. Exit\n");
        printf("\nPlease enter your choice (1-6): ");
	scanf("%d", &choice);

	switch(choice)
	{
	    case 1: print(m1); break;
	    case 2: sort(m1); break;
	    case 3: add(m1); break;
	    case 4: delete(m1); break;
	    case 5: search(m1); break;
	    default: leave(); break;
	}
    } while(choice != 6);

    free(m1);
    free(m2);
    fclose(input);

    return 0;
}

    // Free last memory location and update size
    free(m1 + size - 1);

    if(check == 0)
    {
	m1 = (struct mail *) realloc(m1, (size + 1) * sizeof(m1temp));