Move insert logic from add command into feed_info.c

feed_info.c

@@ -15,23 +15,18 @@
 #include "config.h"
 #include "feed_info.h"
 
+static const char *ZBLOCK_FEED_INFO_ERRORS[] = {
+	"OK",
+	"Invalid arguments provided",
+	"An error was encountered with the feed database",
+	"The feed already exists",
+	"The feed does not exist"
+};
+static_assert(sizeof(ZBLOCK_FEED_INFO_ERRORS) / sizeof(*ZBLOCK_FEED_INFO_ERRORS) == ZBLOCK_FEED_INFO_ERRORCOUNT, "Not all feed info errors implemented");
+
 // returns a string about the result of a feed_info function
 const char *zblock_feed_info_strerror(zblock_feed_info_err error) {
-	static_assert(ZBLOCK_FEED_INFO_ERRORCOUNT == 3, "Not all feed info errors implemented");
+	return error < 0 || error >= ZBLOCK_FEED_INFO_ERRORCOUNT ? "Unspecified error" : ZBLOCK_FEED_INFO_ERRORS[error];
-	switch (error) {
-		case ZBLOCK_FEED_INFO_OK: {
-			return "OK";
-		}
-		case ZBLOCK_FEED_INFO_NULL: {
-			return "No feed info was provided";
-		}
-		case ZBLOCK_FEED_INFO_POSTGRES: {
-			return "An error was encountered with the feed database";
-		}
-		default: {
-			return "Unspecified error";
-		}
-	}
 }
 
 // format string for for the time format of pubDate
@@ -45,7 +40,56 @@ time_t pubDate_to_time_t(char *s) {
 	return mktime(&tm);
 }
 
+// check if the feed currently exists. the result is in the exists pointer.
+zblock_feed_info_err zblock_feed_info_exists(PGconn *conn, const char *url, u64snowflake channel_id, int *exists) {
+	if (!conn || !exists) return ZBLOCK_FEED_INFO_INVALID_ARGS;
+	
+	char channel_id_str[21]; // hold a 64-bit int in decimal form
+	snprintf(channel_id_str, sizeof(channel_id_str), "%ld", channel_id);
+	
+	const char *const params[] = {url, channel_id_str};
+	PGresult *res = PQexecParams(conn, "SELECT COUNT(1) FROM feeds WHERE url = $1 AND channel_id = $2", 2, NULL, params, NULL, NULL, 0);
+	if (PQresultStatus(res) != PGRES_TUPLES_OK) {
+		PQclear(res);
+		return ZBLOCK_FEED_INFO_DBERROR;
+	}
+	
+	*exists = *(int *) PQgetvalue(res, 0, 0);
+	PQclear(res);
+	return ZBLOCK_FEED_INFO_OK;
+}
+
 // Insert new feed into the database
 zblock_feed_info_err zblock_feed_info_insert(PGconn *conn, zblock_feed_info *feed) {
-	assert(0 && "not implemented yet");
+	if (!conn || !feed) return ZBLOCK_FEED_INFO_INVALID_ARGS;
+
+	// check if the feed already exists
+	{
+		int feed_exists = 0;
+		zblock_feed_info_err exists_error = zblock_feed_info_exists(conn, feed->url, feed->channel_id, &feed_exists);
+		if (exists_error) {
+			return exists_error;
+		} else if (feed_exists) {
+			return ZBLOCK_FEED_INFO_EXISTS;
+		}	
+	}
+
+	// I don't want to deal with the extra fuss that is sending these in binary format
+	char channel_id_str[21];
+	snprintf(channel_id_str, sizeof(channel_id_str), "%ld", feed->channel_id);
+	char guild_id_str[21];
+	snprintf(guild_id_str, sizeof(guild_id_str), "%ld", feed->guild_id);
+	const char *const insert_params[] = {feed->url, feed->last_pubDate, channel_id_str, feed->title, guild_id_str};
+	PGresult *insert_res = PQexecParams(conn,
+		"INSERT INTO feeds (url, last_pubDate, channel_id, title, guild_id) VALUES ($1, $2, $3, $4, $5)",
+		5, NULL, insert_params, NULL, NULL, 0
+	);
+	
+	zblock_feed_info_err result = ZBLOCK_FEED_INFO_OK;
+	if (PQresultStatus(insert_res) != PGRES_COMMAND_OK) {
+		result = ZBLOCK_FEED_INFO_DBERROR;
+	}
+	
+	PQclear(insert_res);
+	return result;
 }

feed_info.h

@@ -23,8 +23,10 @@ typedef struct {
 
 typedef enum {
 	ZBLOCK_FEED_INFO_OK,
-	ZBLOCK_FEED_INFO_NULL,
+	ZBLOCK_FEED_INFO_INVALID_ARGS,
-	ZBLOCK_FEED_INFO_POSTGRES,
+	ZBLOCK_FEED_INFO_DBERROR,
+	ZBLOCK_FEED_INFO_EXISTS,
+	ZBLOCK_FEED_INFO_NOT_EXIST,
 	ZBLOCK_FEED_INFO_ERRORCOUNT
 } zblock_feed_info_err;
 
@@ -34,6 +36,9 @@ time_t pubDate_to_time_t(char *s);
 // returns a string about the result of a feed_info function
 const char *zblock_feed_info_strerror(zblock_feed_info_err error);
 
+// check if the feed currently exists. the result is in the exists pointer.
+zblock_feed_info_err zblock_feed_info_exists(PGconn *conn, const char *url, u64snowflake channel_id, int *exists);
+
 // Insert new feed into the database
 zblock_feed_info_err zblock_feed_info_insert(PGconn *conn, zblock_feed_info *feed);
 

main.c

@@ -217,25 +217,6 @@ static void bot_command_add(struct discord *client, const struct discord_interac
 	feed.channel_id = event->channel_id;
 	feed.guild_id = event->guild_id;
 	
-	// check if it already exists
-	char channel_id_str[21]; // hold a 64-bit int in decimal form
-	snprintf(channel_id_str, sizeof(channel_id_str), "%ld", feed.channel_id);
-	
-	const char *const select_params[] = {feed.url, channel_id_str};
-	PGresult *select_res = PQexecParams(database_conn, "SELECT * from feeds WHERE url = $1 AND channel_id = $2", 2, NULL, select_params, NULL, NULL, 0);
-	if (PQresultStatus(select_res) != PGRES_TUPLES_OK) {
-		snprintf(msg, sizeof(msg), "Error adding feed: %s", PQresultErrorMessage(select_res));
-		PQclear(select_res);
-	}
-	
-	if (PQntuples(select_res) > 0) {
-		PQclear(select_res);
-		snprintf(msg, sizeof(msg), "Error adding feed: it has already been added to this channel");
-		goto send_msg;
-	} else {
-		PQclear(select_res); // don't actually do anything with the contents of the query
-	}
-	
 	mrss_t *mrss_feed;
 	mrss_error_t mrss_error = mrss_parse_url(feed.url, &mrss_feed);
 	if (mrss_error) {
@@ -246,22 +227,15 @@ static void bot_command_add(struct discord *client, const struct discord_interac
 	feed.title = mrss_feed->title;
 	feed.last_pubDate = mrss_feed->item->pubDate;
 	
-	char guild_id_str[21];
+	zblock_feed_info_err insert_res = zblock_feed_info_insert(database_conn, &feed);
-	snprintf(guild_id_str, sizeof(guild_id_str), "%ld", feed.guild_id);
+	if (insert_res) {
-	const char *const insert_params[] = {feed.url, feed.last_pubDate, channel_id_str, feed.title, guild_id_str};
-	PGresult *insert_res = PQexecParams(database_conn,
-		"INSERT INTO feeds (url, last_pubDate, channel_id, title, guild_id) VALUES ($1, $2, $3, $4, $5)",
-		5, NULL, insert_params, NULL, NULL, 0
-	);
-	if (PQresultStatus(insert_res) != PGRES_COMMAND_OK) {
 		// write error message
-		snprintf(msg, sizeof(msg), "Error adding feed: %s", PQresultErrorMessage(insert_res));
+		snprintf(msg, sizeof(msg), "Error adding feed: %s", zblock_feed_info_strerror(insert_res));
 	} else {
 		// write the confirmation message
 		snprintf(msg, sizeof(msg), "The following feed has been successfully added to this channel:\n`%s`", feed.url);
 	}
 	
-	PQclear(insert_res);
 	mrss_free(mrss_feed);
 	
 	send_msg: