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

//#define MAX_DATA 512
//#define MAX_ROWS 100

struct Address {
    int id;
    int set;
    char *name;
    char *email;
};

struct Database {
    int MAX_DATA;
    int MAX_ROWS;
    struct Address **rows; // USE ARRAY OF POINTERS
};

struct Connection {
    FILE *file;
    struct Database *db;
};

void die(const char *message)
{
    if(errno) {
        perror(message);
    } else {
        printf("ERROR: %s\n", message);
    }

    exit(1);
}

void Address_print(struct Address *addr)
{
    printf("%d %s %s\n", addr->id, addr->name, addr->email);
}

void Database_load(struct Connection *conn)
{
    size_t i=0;

    // Each database will have two `int` values. read
    // those first.
    assert(conn->db && conn->file);
    if (!(conn->db && conn->file))
        die("Database load : Invalid Connection info");
    if (fread(&conn->db->MAX_DATA, sizeof(conn->db->MAX_DATA), 1, conn->file) != 1)
        die("Database load : Couldn't read MAX_DATA");
    if (fread(&conn->db->MAX_ROWS, sizeof(conn->db->MAX_ROWS), 1, conn->file) != 1)
        die("Database load : Couldn't read MAX_ROWS");
    conn->db->rows = (struct Address**)malloc(sizeof(struct Address *) * conn->db->MAX_ROWS);
//  printf("Sizeof *conn->db->rows is %lu\n", sizeof(*conn->db->rows));
    assert(conn->db->rows);
    if (!(conn->db->rows))
        die("Database_load : Could not MAX_ROWS Address  structures");
    // Now load each address structure
    for (i=0; i<conn->db->MAX_ROWS; i++) {
        // read two int values first.

        conn->db->rows[i] = (struct Address*)malloc(sizeof(struct Address));
        struct Address *row = conn->db->rows[i];
        if (fread(&row->id, sizeof(row->id), 1, conn->file) !=1)
            die("Database load : Could not read Address::id");
        if (fread(&row->set, sizeof(row->set), 1, conn->file) != 1)
            die("Database load : Couldn't read  Address::set");
        // allocate two buffers large enough for our data
        row->name = malloc(conn->db->MAX_DATA * sizeof(*row->name));
        row->email = malloc(conn->db->MAX_DATA * sizeof(*row->email));
        assert(row->email && row->name);
        if (!(row->name && row->email))
            die("Database load : Failed to Allocate Address strings");
        // now just read both strings
        if (fread(row->name, conn->db->MAX_DATA * sizeof(*row->name), 1, conn->file) != 1)
            die("Database load : Failed to read Address::name");
        if (fread(row->email, conn->db->MAX_DATA * sizeof(*row->email), 1, conn->file) != 1)
            die("Database load : Failed to read Address::email");
    }
}

struct Connection *Database_open(const char *filename, char mode)
{
    struct Connection *conn = malloc(sizeof(struct Connection));
    if(!conn) die("Memory error");

    conn->db = malloc(sizeof(struct Database));
    if(!conn->db) die("Memory error");

    if(mode == 'c') {
        conn->file = fopen(filename, "w");
    } else {
        conn->file = fopen(filename, "r+");

        if(conn->file) {
            Database_load(conn);
        }
    }

    if(!conn->file) die("Failed to open the file");

    return conn;
}

void Database_close(struct Connection *conn)
{
        size_t i;
        if(conn) {
                if (conn->db && conn->db->rows) {
                        for (i = 0; i < conn->db->MAX_ROWS; i++) {

                                struct Address *cur = conn->db->rows[i];
                                free(cur);

                        }
                }

                if(conn->file) fclose(conn->file);
                if(conn->db) free(conn->db);
                free(conn);
        }
}


void Database_write(struct Connection *conn)
{
    size_t i = 0;
    rewind(conn->file);
    // Writing MAX_DATA and MAX_ROWS to the file first
    if(fwrite(&conn->db->MAX_DATA, sizeof(conn->db->MAX_DATA), 1, conn->file) != 1)
        die("Database write : Failed to write MAX_DATA");
    if(fwrite(&conn->db->MAX_ROWS, sizeof(conn->db->MAX_ROWS), 1, conn->file) != 1)
        die("Database write : Failed to write MAX_ROWS");
    // Writing Address's list now
    for (i=0; i<conn->db->MAX_ROWS; i++) {
        struct Address *row = conn->db->rows[i];
        if (fwrite(&row->id, sizeof(row->id), 1, conn->file) != 1)
            die("Database write : Failed to write Address(id)");
        if (fwrite(&row->set, sizeof(row->set), 1, conn->file) != 1)
            die("Database write : Failed to write Address(set)");
        if (fwrite(row->name, sizeof(char)*conn->db->MAX_DATA, 1, conn->file) != 1)
            die("Database write : Failed to write Address(name)");
        if (fwrite(row->email, sizeof(char)*conn->db->MAX_DATA, 1, conn->file) != 1)
            die("Database write : Failed to write Address(email)");
    }
    if (fflush(conn->file) == -1)
        die("Database_write : Cannot flush database.");
}

void Database_create(struct Connection *conn, int MAX_DATA, int MAX_ROWS)
{
        int i = 0;
        conn->db->MAX_DATA = MAX_DATA;
        conn->db->MAX_ROWS = MAX_ROWS;
        conn->db->rows = (struct Address**)malloc(sizeof(struct Address*) * MAX_ROWS);

        for(i = 0; i < MAX_ROWS; i++) {
                conn->db->rows[i] = (struct Address*)malloc(sizeof(struct Address));
                conn->db->rows[i]->id = i;
                conn->db->rows[i]->set = 0;
                conn->db->rows[i]->name = (char *)malloc(conn->db->MAX_DATA);
                conn->db->rows[i]->name = (char *)memset(conn->db->rows[i]->name, ' ', conn->db->MAX_DATA);
                conn->db->rows[i]->email= (char *)malloc(conn->db->MAX_DATA);
                conn->db->rows[i]->email= (char *)memset(conn->db->rows[i]->email, ' ', conn->db->MAX_DATA);

        }
}

void Database_set(struct Connection *conn, int id, const char *name, const char *email)
{
    if (!(conn && conn->db && conn->db->rows && conn->db->rows[id])) return;

    struct Address *addr = conn->db->rows[id];
    int MAX_DATA = conn->db->MAX_DATA;
    if(addr->set == 1) die("Already set, delete it first");

    addr->set = 1;
    addr->name = malloc(sizeof(char) * MAX_DATA);
    addr->email = malloc(sizeof(char) * MAX_DATA);

    char *res = strncpy(addr->name, name, MAX_DATA);
    if(!res) die("Name copy failed");

    res = strncpy(addr->email, email, MAX_DATA);
    if(!res) die("Email copy failed");
}

void Database_get(struct Connection *conn, int id)
{
    struct Address *addr = conn->db->rows[id];

    if(addr->set) {
        Address_print(addr);
    } else {
        die("ID is not set");
    }
}

void Database_delete(struct Connection *conn, int id)
{
    struct Address addr = {.id = id, .set = 0};
    conn->db->rows[id] = &addr;
}

void Database_list(struct Connection *conn)
{
    int i = 0;
    struct Database *db = conn->db;
    int MAX_ROWS = conn->db->MAX_ROWS;
    for(i = 0; i < MAX_ROWS; i++) {
        struct Address *cur = db->rows[i];

        if(cur->set) {
            Address_print(cur);
        }
    }
}

int main(int argc, char *argv[])
{
    if(argc < 3) die("USAGE: ex17 <dbfile> <action> [action params]");

    char *filename = argv[1];
    char action = argv[2][0];
    struct Connection *conn = Database_open(filename, action);
    int id = 0;

//    if(argc > 3) id = atoi(argv[3]);
 //   if(id >= MAX_ROWS) die("There's not that many records.");

    switch(action) {
        case 'c':
        if(argc < 5) die("Required: MAX_DATA, MAX_ROWS");
            Database_create(conn, atoi(argv[3]), atoi(argv[4]));
            Database_write(conn);
            break;

        case 'g':
            if(argc != 4) die("Need an id to get");

            Database_get(conn, atoi(argv[3]));
            break;

        case 's':
            if(argc != 6) die("Need id, name, email to set");
            Database_set(conn, atoi(argv[3]), argv[4], argv[5]);
            Database_write(conn);
            break;

        case 'd':
            if(argc != 4) die("Need id to delete");

            Database_delete(conn, id);
            Database_write(conn);
            break;

        case 'l':
            Database_list(conn);
            break;
        default:
            die("Invalid action, only: c=create, g=get, s=set, d=del, l=list");
    }

    Database_close(conn);

    return 0;
}