fix-end-date-printing (#2)

printing of the end date was fixed

Reviewed-on: bjoernf/ics_analyzer#2
Co-authored-by: bjoernf <bjoern.foersterling@web.de>
Co-committed-by: bjoernf <bjoern.foersterling@web.de>

README.md

@@ -42,6 +42,6 @@ sudo make uninstall
 
 #### TODO
 
-- add option to print upcoming events only until a certain date
-- show end date for events that span over multiple days
+- fix bug when LOCATION field is present
+- cap the number of upcoming events being printed (and introduce --all option)
 - tests

docs/ics_format.txt

@@ -13,6 +13,8 @@ an all day event can span over multiple days and look like this:
 DTSTART;VALUE=DATE:20230911^M$
 DTEND;VALUE=DATE:20230916^M$
 
+The DTEND of an all day event is exclusively, it is not an all day event anymore!
+
 appointment:
 DTSTART;TZID=/freeassociation.sourceforge.net/Continent/City:
  20230909T090000

src/date_time_handling.c

@@ -59,17 +59,69 @@ void marshall_date_time(char date_time[]) {
 	strcpy(date_time, transformed_string);
 }
 
-void print_end_date(char end_date[]) {
+void print_end_date(char end_date[], char start_date[]) {
+	time_t start_uts = transform_date_to_unix_ts(start_date);
+	time_t end_uts = transform_date_to_unix_ts(end_date);
+	double time_difference = difftime(end_uts, start_uts);
+
 	// end_date is all day event
-	if (strlen(end_date) == 8)
-		return;
+	if (strlen(end_date) == 8) {
+		if (time_difference == 86400) {
+			return;
+		} else {
+			printf (" - ");
+			end_uts -= 86400;
+			char *end_date_minus_one = transform_unix_ts_to_date(end_uts);
+			pretty_print_date_time(end_date_minus_one);
+			free(end_date_minus_one);
+			return;
+		}
+	} else {
+		// end_date is not an all day event
 
-	strtok(end_date, "T");
-	char *time = strtok(NULL, "T");
+		char *end_date_chunk = strtok(end_date, "T");
+		char *end_time_chunk = strtok(NULL, "T");
+		char *start_date_chunk = strtok(start_date, "T");
 
-	printf (" - %c%c:", time[0], time[1]);
-	printf ("%c%c:", time[2], time[3]);
-	printf ("%c%c", time[4], time[5]);
+		printf (" - ");
+
+		// only print the end date if it is not the same as the start date
+		if (strcmp(start_date_chunk, end_date_chunk) != 0) {
+			printf("%c%c%c%c-", end_date_chunk[0], end_date_chunk[1], \
+			end_date_chunk[2], end_date_chunk[3]);
+			printf("%c%c-", end_date_chunk[4], end_date_chunk[5]);
+			printf("%c%c ", end_date_chunk[6], end_date_chunk[7]);
+		}
+		
+		printf ("%c%c:", end_time_chunk[0], end_time_chunk[1]);
+		printf ("%c%c:", end_time_chunk[2], end_time_chunk[3]);
+		printf ("%c%c", end_time_chunk[4], end_time_chunk[5]);
+	}
+}
+
+// YYYYmmdd -> unix timestamp
+time_t transform_date_to_unix_ts(char date_str[]) {
+	time_t unix_stamp = 0;
+	int date_only = atoi(date_str);
+	struct tm my_tm = {0};
+	my_tm.tm_year = date_only / 10000 - 1900;
+	my_tm.tm_mon = (date_only % 10000) / 100 - 1;
+	my_tm.tm_mday = date_only % 100;
+
+	unix_stamp = mktime(&my_tm);
+
+	return unix_stamp;
+}
+
+// unix timestamp -> YYYYmmdd
+// make sure to free the returned buffer
+char *transform_unix_ts_to_date(time_t unix_ts) {
+	char *date_buffer = malloc(9);
+	struct tm *my_tm;
+	my_tm = localtime(&unix_ts);
+	strftime(date_buffer, 9, "%Y%m%d", my_tm);
+
+	return date_buffer;
 }
 
 char *get_tz() {

src/date_time_handling.h

@@ -5,4 +5,6 @@ void get_date(char buffer[]);
 char *get_tz();
 void pretty_print_date_time(char date_time[]);
 void marshall_date_time(char date_time[]);
-void print_end_date(char end_date[]);
+void print_end_date(char end_date[], char start_date[]);
+time_t transform_date_to_unix_ts(char date_str[]);
+char *transform_unix_ts_to_date(time_t unix_ts);

src/list_handling.c

@@ -50,7 +50,7 @@ void print_upcoming(struct event *head, char current_start_date[]) {
 	while (head != NULL) {
 		if (strcmp(head->start_date, current_start_date) >= 0) {
 			pretty_print_date_time(head->start_date);
-			print_end_date(head->end_date);
+			print_end_date(head->end_date, head->start_date);
 			printf("\n%s\n", head->summary);
 			if (head->next != NULL)
 				printf("\n");