// email_management_system.c
// Tammy Zhong
// Implementation file for email management system functions
// Modified by Angela Finlayson
// (TODO)

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

#include "email_management_system.h"

// Function prototypes 
// ADD YOUR OWN FUNCTION PROTOTYPES HERE 
struct email *create_email(char sender[], char subject[], double size, 
    enum email_type type, int priority, struct email *next);

void free_emails(struct email *head);

// Function definitions

// Creates a new empty email folder 
//(TODO)
struct folder *create_folder(char name[]) {
    struct folder *new_folder = malloc(sizeof(struct folder));
    strcpy(new_folder->name, name);
    new_folder->emails = NULL;
    return new_folder;
}

// Add a new email to the folder at the head 
// Similar to previous lecture code insert_head
// (TODO)
void insert_email_at_head(struct folder *email_folder, char sender[], 
    char subject[], double size, enum email_type type, int priority) {
    
    struct email *new_email = create_email(sender, subject, size, type, 
                                        priority, NULL);
    new_email->next = email_folder->emails;
    email_folder->emails = new_email;
}

// Given a string, look for email where the subject is this string 
// (TODO)
struct email *search_email(struct folder *email_folder, char subject[]) {
    struct email *current = email_folder->emails;
    while (current != NULL) {
        if (strcmp(current->subject, subject) == 0) {
            return current;
        }
        current = current->next;
    }
    return NULL;
}

// Removes all emails from a folder
// clears and delete associated memory of folder and emails in it
void clear_folder(struct folder *email_folder) {
    free_emails(email_folder->emails);
    free(email_folder);
}

// Remove email(s) with certain priority (e.g. filter out low priority emails)
void delete_email_of_priority(struct folder *email_folder, int priority) {
    struct email *previous = NULL;
    struct email *current = email_folder->emails;

    while (current != NULL) {
        if (current->priority == priority) {
            if (previous == NULL) {
                email_folder->emails = email_folder->emails->next;
                free(current);
                current = email_folder->emails;
            } else {
                previous->next = current->next;
                free(current);
                current = previous->next;
            }
            
        } else {
            previous = current;
            current = current->next;
        }
    }
}

// Append emails from folder_2 after folder_1 and returns them in the one folder
// Assumption made here assumes not same subject email in folder_1 and folder_2
struct folder *merge_folders(char merged_folder_name[], 
    struct folder *folder_1, struct folder *folder_2) {
   
    struct folder *new_folder = create_folder(merged_folder_name);

    if (folder_1->emails == NULL) {
        new_folder->emails = folder_2->emails;
    } else {
        //Find the last node of the first list
        struct email *current = folder_1->emails;
        while (current->next != NULL) {
            current = current->next;
        }
        current->next = folder_2->emails;
        new_folder->emails = folder_1->emails;
    }
    free(folder_1);
    free(folder_2);
    return new_folder;
}

// Split emails in a given folder into 3 folders based on email type 
// keeping original ordering
// assumption: inbox, sent and draft are folders already malloc-ed and initialised
void split_folder(struct folder *given_folder, 
    struct folder *inbox, struct folder *sent, struct folder *draft) {
    // TODO: implement this function
    printf("split_folder not yet implemented.\n");
    exit(1);
}



// CHALLENGE Returns number of emails in a given folder 
// (TODO: Improve this)
int count_emails(struct folder *email_folder) {
    int counter = 0;
    struct email *current = email_folder->emails;
    while (current != NULL) {
        counter++;
        current = current->next;
    }
    return counter;
}

// CHALLENGE at home for fun: Sort emails in folder based on size
// (slightly out of scope of COMP1511 - touches on sorting algorithms)
// order doesn't matter if two emails of same size
void sort_emails(struct folder *email_folder) {
    // TODO: implement this function
    printf("sort_emails not yet implemented.\n");
    exit(1);
}

// Your functions here (include function comments):

//
struct email *create_email(char sender[], char subject[], double size, 
    enum email_type type, int priority, struct email *next) {

    struct email *new_email = malloc(sizeof(struct email));
    strcpy(new_email->sender, sender);
    strcpy(new_email->subject, subject);
    new_email->size = size;
    new_email->type = type;
    new_email->priority = priority;
    new_email->next = next;
    return new_email;
}

void free_emails(struct email *head) {
    struct email *current = head;
    while (current != NULL) {
        head = head->next;
        free(current);
        current = head;
    }
}

////////////////////////////////////////////////////////////////////////////////
//                              Provided Code                              //
////////////////////////////////////////////////////////////////////////////////

// Print/display all emails in folder 
// Similar to previous lecture code print_list
void print_emails(struct folder *email_folder) {
    printf("Folder Name: %s\n", email_folder->name);
    struct email *current = email_folder->emails;

    if (current == NULL) {
        printf("There are no emails in this folder.\n");
    }

    while (current != NULL) {
        printf("---\n");
        print_single_email(current);
        current = current->next;
    }
}

// Prints out details of a single email 
void print_single_email(struct email *email) {
    if (email == NULL) {
        printf("Email is NULL.\n");
        return;
    }

    printf("Sender: %s\n", email->sender);
    printf("Subject: %s\n", email->subject);
    printf("Size: %lfmb\n", email->size);
    printf("Type: ");
    if (email->type == RECEIVED) {
        printf("RECEIVED\n");
    } else if (email->type == SENT) {
        printf("SENT\n");
    } else if (email->type == DRAFT) {
        printf("DRAFT\n");
    } else {
        printf("UNKNOWN\n");
    }
    printf("Priority: ");
    if (email->priority == HIGH_PRIORITY) {
        printf("HIGH_PRIORITY\n");
    } else if (email->priority == NORMAL_PRIORITY) {
        printf("NORMAL_PRIORITY\n");
    } else if (email->priority == LOW_PRIORITY) {
        printf("LOW_PRIORITY\n");
    } else {
        printf("UNKNOWN\n");
    }
}