Cleans up the code

Separates some functions into their own files
separates some big functions in to smaller ones to help improve the code
cleans up some stuff

Makefile

@@ -1,4 +1,4 @@
 all: main.c
-	gcc main.c -lcurl -lcjson -o isbn -Wall
+	gcc main.c json.c curl.c -lcurl -lcjson -o isbn -Wall
 clean:
 	rm isbn

curl.c

@@ -0,0 +1,67 @@
+#include <curl/curl.h>
+#include <curl/easy.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "curl.h"
+
+#define BASE_URL_SIZE 38
+
+void init_string(string* s)
+{
+	s->len = 0;
+	s->buf = malloc(s->len + 1);
+
+	if (NULL == s->buf) {
+		fprintf(stderr, "malloc() failed!\n");
+		exit(EXIT_FAILURE);
+	}
+	s->buf[0] = '\0';
+}
+
+size_t writefunc(void* ptr, size_t size, size_t nmemb, string* s)
+{
+	size_t new_len = s->len + (size * nmemb);
+	s->buf = realloc(s->buf, new_len + 1);
+	if (NULL == s->buf) {
+		fprintf(stderr, "realloc() failed!\n");
+		exit(EXIT_FAILURE);
+	}
+	memcpy(s->buf + s->len, ptr, size * nmemb);
+	s->buf[new_len] = '\0';
+	s->len = new_len;
+	return size * nmemb;
+}
+
+CURLcode perform_book_get(char* isbn, string* s)
+{
+	CURL* handler;
+	char* base_url;
+	size_t finalurl_size = BASE_URL_SIZE + 15;
+	char finalurl[finalurl_size];
+	CURLcode result;
+
+	handler = curl_easy_init();
+	if (!handler) {
+		fprintf(stderr, "cURL failed to initialize!\n");
+		exit(EXIT_FAILURE);
+	}
+
+	base_url = "https://openlibrary.org/search.json?q=";
+
+	// Setup the URL for the request
+	snprintf(finalurl, finalurl_size, "%s%s", base_url, isbn);
+
+	curl_easy_setopt(handler, CURLOPT_URL, finalurl);
+	curl_easy_setopt(handler, CURLOPT_HTTPGET, 1L);
+	curl_easy_setopt(handler, CURLOPT_WRITEFUNCTION, writefunc);
+	curl_easy_setopt(handler, CURLOPT_WRITEDATA, s);
+
+	result = curl_easy_perform(handler);
+
+	// Always clean up
+	curl_easy_cleanup(handler);
+
+	return result;
+
+}

curl.h

@@ -0,0 +1,40 @@
+#ifndef CURL_H
+#define CURL_H
+
+/**
+ * struct string_t
+ * char* buf - The buffer containing the string data
+ * size_t len - The length of the buffer
+ */
+typedef struct string_t {
+	char* buf;
+	size_t len;
+} string;
+
+/**
+ * void init_string
+ * string* s - The string struct
+ *
+ * Initializes the string struct
+ */
+void init_string(string* s);
+
+/**
+ * size_t writefunc
+ *
+ * The arguments from CURLOPT_WRITEFUNCTION
+ *
+ * Writes the cURL get into the string struct
+ */
+size_t writefunc(void* ptr, size_t size, size_t nmemb, string* s);
+
+/**
+ * CURLcode perform_book_get
+ * char* isbn - The ISBN
+ * string* s - The string struct to place the GET output in
+ *
+ * Performs a GET request with the ISBN
+ */
+CURLcode perform_book_get(char* isbn, string* s);
+
+#endif

json.c

@@ -0,0 +1,70 @@
+#include <curl/curl.h>
+#include <cjson/cJSON.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "curl.h"
+#include "json.h"
+
+#define MAX_BUF_LEN 1024
+
+void check_valid_query(cJSON* numfound)
+{
+	if (0 != numfound->valueint)
+		return;
+	fprintf(stderr, "No ISBN found!\n");
+	exit(EXIT_FAILURE);
+}
+
+void get_authors(cJSON* bookinfo, char authors[256])
+{
+	char* temp_author;
+	size_t new_len;
+	cJSON* author_arr = cJSON_GetObjectItemCaseSensitive(bookinfo, "author_name")->child;
+
+	snprintf(authors, strlen(author_arr->valuestring) + 1, "%s", author_arr->valuestring);
+	author_arr = author_arr->next;
+
+	while (NULL != author_arr) {
+		// The plus 1 is for the \0, the plus 2 is for the ", "
+		new_len = strlen(authors) + strlen(author_arr->valuestring) + 1 + 2;
+
+		temp_author = malloc(sizeof(char) * new_len);
+		snprintf(temp_author, new_len, "%s, %s", authors, author_arr->valuestring);
+		memcpy(authors, temp_author, new_len);
+
+		free(temp_author);
+
+		author_arr = author_arr->next;
+	}
+}
+
+void parse_json(string* s, char* isbn, book_t* book)
+{
+	char authors[MAX_BUF_LEN];
+
+	cJSON* json = cJSON_Parse(s->buf);
+	if (NULL == json) {
+		const char* error_ptr = cJSON_GetErrorPtr();
+		if (NULL != error_ptr)
+			fprintf(stderr, "JSON error: %s\n", error_ptr);
+		cJSON_Delete(json);
+		exit(EXIT_FAILURE);
+	}
+
+	check_valid_query(cJSON_GetObjectItemCaseSensitive(json, "numFound"));
+
+	cJSON* bookinfo = cJSON_GetObjectItemCaseSensitive(json, "docs")->child;
+
+	book->isbn = isbn;
+	book->title = cJSON_GetObjectItemCaseSensitive(bookinfo, "title")->valuestring;
+	book->year_of_publication = cJSON_GetObjectItemCaseSensitive(bookinfo, "first_publish_year")->valueint;
+	book->page_len = cJSON_GetObjectItemCaseSensitive(bookinfo, "number_of_pages_median")->valueint;
+
+	get_authors(bookinfo, authors);
+
+	// Need to malloc, because we need to copy authors into the book struct
+	book->authors = (char*) malloc(sizeof(char) * (strlen(authors) + 1));
+	memcpy(book->authors, authors, strlen(authors) + 1);
+}

json.h

@@ -0,0 +1,40 @@
+#ifndef JSON_H
+#define JSON_H
+
+#define MAX_BUF_LEN 1024
+
+typedef struct book_t {
+	char* isbn;
+	char* title;
+	char* authors;
+	int year_of_publication;
+	int page_len;
+} book_t;
+
+/**
+ * void check_valid_query
+ * cJSON* numfound - The json entry that contains the numFound value
+ *
+ * Checks if there are any search results in this json entry
+ */
+void check_valid_query(cJSON* numfound);
+
+/**
+ * void get_authors
+ * cJSON* bookinfo - The JSON entry that has all of the information about the book
+ * char* authors - The string to fill
+ *
+ * Takes the JSON entry from bookinfo and combines all of the authors into one final string
+ */
+void get_authors(cJSON* bookinfo, char* authors);
+
+/**
+ * void parse_json
+ * string* s - The string struct
+ * char* isbn - The ISBN
+ * book_t* book - The struct to fill with book information
+ *
+ * Parses through the given JSON entry and gathers all of the information we need
+ */
+void parse_json(string* s, char* isbn, book_t* book);
+#endif

main.c

@@ -1,115 +1,27 @@
 #include <curl/curl.h>
+#include <cjson/cJSON.h>
 #include <stdio.h> 
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 
-#include <cjson/cJSON.h>
+#include "curl.h"
+#include "json.h"
 
-#define BASE_URL_SIZE 38
 #define FILE_NAME "books.csv"
 
 #define MAX_BUF_LEN 1024 
 
-/**
+void print_book(book_t* book)
- * struct string_t
- * char* buf - The buffer containing the string data
- * size_t len - The length of the buffer
- */
-typedef struct string_t {
-	char* buf;
-	size_t len;	
-} string;
-
-/**
- * void init_string
- * string* s - The string struct
- *
- * Initializes the string struct */
-void init_string (string* s)
 {
-	s->len = 0;
+	printf("ISBN: %s\n", book->isbn);
-	s->buf = malloc(s->len + 1);
+	printf("Title: %s\n", book->title);
-
+	printf("Author(s): %s\n", book->authors);
-	if (NULL == s->buf) {
+	printf("(First) Year of Publication: %d\n", book->year_of_publication);
-		fprintf(stderr, "malloc() failed\n"); exit(EXIT_FAILURE);
+	printf("Page length: %d\n", book->page_len);
-	}
-	s->buf[0] = '\0';
 }
 
-/**
+void write_to_file(book_t* book)
- * size_t writefunc
- *
- * The arguments come from CURLOPT_WRITEFUNCTION
- *
- * Writes the cURL get into the string struct
- */
-size_t writefunc(void* ptr, size_t size, size_t nmemb, string* s)
-{
-	size_t new_len = s->len + (size * nmemb);
-	s->buf = realloc(s->buf, new_len + 1); 
-	if (NULL == s->buf) {
-		fprintf(stderr, "realloc() failed\n");
-		exit(EXIT_FAILURE);
-	}	
-
-	memcpy(s->buf + s->len, ptr, size * nmemb);
-	s->buf[new_len] = '\0';
-	s->len = new_len;
-
-	return size * nmemb;
-}
-
-/**
- * CURLcode perform_book_get
- * char isbn_buf[14] - The ISBN
- * string* s - The string struct to place the GET output in
- *
- * Perforrms a GET request with the ISBN
- */
-CURLcode perform_book_get(char isbn_buf[14], string* s)
-{
-	CURL* handler;
-	char *base_url;
-	size_t finalurl_size = BASE_URL_SIZE + 15;
-	char finalurl[finalurl_size];
-	CURLcode result;
-
-	handler = curl_easy_init();
-	if (!handler) {
-		fprintf(stderr, "cURL failed to initialize!\n");
-		exit(EXIT_FAILURE);
-	}
-
-	base_url = "https://openlibrary.org/search.json?q=";
-	/**
-	 * Setup the URL for the request
-	 */
-	snprintf(finalurl, finalurl_size, "%s%s", base_url, isbn_buf);
-
-	curl_easy_setopt(handler, CURLOPT_URL, finalurl);
-	curl_easy_setopt(handler, CURLOPT_HTTPGET, 1L);
-	curl_easy_setopt(handler, CURLOPT_WRITEFUNCTION, writefunc);
-	curl_easy_setopt(handler, CURLOPT_WRITEDATA, s);
-
-	result = curl_easy_perform(handler);
-
-	// Always clean up	
-	curl_easy_cleanup(handler);
-
-	return result;
-}
-
-void print_book(char* isbn, char* title, char* authors, int year, int page_len)
-{
-	printf("ISBN: %s\n", isbn);
-	printf("Title: %s\n", title);
-	printf("Author(s): %s\n", authors);
-	printf("(First) Year of Publication: %d\n", year);
-	printf("Page length: %d\n", page_len);
-}
-
-void write_to_file(char* isbn, char* title, char* authors, int year, int page_len)
 {
 	FILE* file;
 	int file_exists;
@@ -128,93 +40,18 @@ void write_to_file(char* isbn, char* title, char* authors, int year, int page_le
 	}
 
 	// now we write the information
-	fprintf(file, "\"%s\",\"%s\",\"%s\",%d,%d\n", isbn, title, authors, year, page_len);
+	fprintf(file, "\"%s\",\"%s\",\"%s\",%d,%d\n", 
+			book->isbn, book->title, book->authors, book->year_of_publication, book->page_len);
 
 	fclose(file);
 }
 
-/**
- * void parse_json
- * string* s - Pointer to the string struct
- *
- * Parses the JSON inside of s.buf and prints the information we're looking for
- */
-void parse_json(string* s, char* options, char* isbn_buf)
-{
-	char *title, *temp_author;
-	int year, page_len, new_len;
-	char authors[MAX_BUF_LEN];
-
-	cJSON* json = cJSON_Parse(s->buf);
-	if (NULL == json) {
-		const char* error_ptr = cJSON_GetErrorPtr();
-		if (NULL != error_ptr)
-			fprintf(stderr, "JSON error: %s\n", error_ptr);
-		cJSON_Delete(json);
-		exit(EXIT_FAILURE);	
-	}
-
-	/**
-	 * if there are no results, we should exit
-	 * if theres too many, we should just treat it normally
- 	 */
-	cJSON* numFound = cJSON_GetObjectItemCaseSensitive(json, "numFound");
-	if (0 == numFound->valueint) {
-		fprintf(stderr, "No ISBN found!\n");
-		exit(EXIT_FAILURE);
-	}
-
-	cJSON* docs = cJSON_GetObjectItemCaseSensitive(json, "docs");
-	cJSON* child = docs->child; // this is the JSON object that stores all of the books information
-
-	title = cJSON_GetObjectItemCaseSensitive(child, "title")->valuestring;
-	year = cJSON_GetObjectItemCaseSensitive(child, "first_publish_year")->valueint;
-	page_len = cJSON_GetObjectItemCaseSensitive(child, "number_of_pages_median")->valueint;
-
-	/**
-	 * The author value is a linked list, so we want to loop through each value
-	 */
-
-	cJSON* authors_json = cJSON_GetObjectItemCaseSensitive(child, "author_name");
-	cJSON* authorarr = authors_json->child;
-
-	// we want to do this first out of the loop, because of formatting	
-	snprintf(authors, strlen(authorarr->valuestring) + 1, "%s", authorarr->valuestring);
-	authorarr = authorarr->next;
-	while (NULL != authorarr) {
-		// The plus one is for the \0, the plus two is for the ", "
-		new_len = strlen(authors) + strlen(authorarr->valuestring) + 1 + 2;
-
-		/**
-		 * So first we make a new string to hold the new string temporarily
-		 *
-		 * Then we want to add formatting by using the existing authors string
-		 * along with the next string
-		 *
-		 * Then we memcpy the temp string into the original string
-		 */
-		temp_author = malloc(sizeof(char) * new_len);
-		snprintf(temp_author, new_len, "%s, %s", authors, authorarr->valuestring);
-		memcpy(authors, temp_author, new_len);
-
-		// Free since we malloc'd
-		free(temp_author);
-		authorarr = authorarr->next;
-	}
-
-	if (0 == strcmp(options, "r")) 
-		print_book(isbn_buf, title, authors, year, page_len);
-	else if (0 == strcmp(options, "w"))
-		write_to_file(isbn_buf, title, authors, year, page_len);
-	else
-		fprintf(stderr, "Improper option provided!");
-}
-
 int main(int argc, char* argv[])
 {
 	char isbn_buf[14]; // want to hold a max of 14 so we can hold up to ISBN13s
 	char options[2];
 	CURLcode res;
+	book_t new_book;
 
 	if (3 != argc) {
 		printf("Usage: isbn [isbn] [options]\n");
@@ -227,6 +64,7 @@ int main(int argc, char* argv[])
 		return EXIT_FAILURE;
 	}
 
+
 	/**
 	 * We must initialize cURL
 	 */
@@ -241,6 +79,11 @@ int main(int argc, char* argv[])
 	 * Grab the formatting options from argv
 	 */
 	snprintf(options, 2, "%s", argv[2]);
+	if (!(('w' == options[0]) || ('r' == options[0]))) {
+		fprintf(stderr, "Invalid option submitted!\n");
+		return EXIT_FAILURE;
+	}
+
 
 	/**
 	 * Setup the output string
@@ -257,16 +100,25 @@ int main(int argc, char* argv[])
 		return EXIT_FAILURE;
 	}
 
+
 	/**
 	 * Now we want to parse the JSON input
 	 */
-	parse_json(&get_output, options, isbn_buf);
+	parse_json(&get_output, isbn_buf, &new_book);
 
 	/**
 	 * We need to free this string
 	 */
 	free(get_output.buf);
 
+	/**
+	 * NOW we either print or save the book
+	 */
+	if (options[0] == 'w')
+		write_to_file(&new_book);
+	else if (options[0] == 'r')
+		print_book(&new_book);
+
 
 	return 0;
 }