getting fancy with command line args

src/args.c

@@ -0,0 +1,103 @@
+#include "args.h"
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+void print_usage(const char *program_name) {
+	printf("Usage: %s [OPTIONS]\n", program_name);
+	printf("Calculate the church calendar for the current year.\n\n");
+	printf("Options:\n");
+	printf("  --all              Print all days in the current liturgical year\n");
+	printf("  --date MM-DD-YYYY  Print the liturgical day for the specified date\n");
+	printf("  --year YYYY        Print all days in the specified year\n");
+	printf("  --help             Display this help message\n");
+	printf("\nWith no options, prints only today's liturgical day.\n");
+}
+
+static int parse_date(const char *date_str, struct tm *date) {
+	int month, day, year;
+	
+	if (sscanf(date_str, "%d-%d-%d", &month, &day, &year) != 3) {
+		return -1;
+	}
+	
+	// Validate ranges
+	if (month < 1 || month > 12 || day < 1 || day > 31 || year < 1900 || year > 9999) {
+		return -1;
+	}
+	
+	memset(date, 0, sizeof(struct tm));
+	date->tm_mon = month - 1;
+	date->tm_mday = day;
+	date->tm_year = year - 1900;
+	
+	// Normalize the date
+	if (mktime(date) == -1) {
+		return -1;
+	}
+	
+	return 0;
+}
+
+int parse_args(int argc, char *argv[], ProgramArgs *args) {
+	// Initialize with defaults
+	args->mode = MODE_TODAY;
+	time_t now = time(NULL);
+	struct tm *today = localtime(&now);
+	args->target_date = *today;
+	args->target_year = today->tm_year + 1900;
+	
+	for (int i = 1; i < argc; i++) {
+		if (strcmp(argv[i], "--help") == 0) {
+			print_usage(argv[0]);
+			return 1;
+		} else if (strcmp(argv[i], "--all") == 0) {
+			args->mode = MODE_ALL;
+		} else if (strcmp(argv[i], "--date") == 0) {
+			if (i + 1 >= argc) {
+				fprintf(stderr, "Error: --date requires a date argument (MM-DD-YYYY)\n");
+				return -1;
+			}
+			
+			if (parse_date(argv[i + 1], &args->target_date) != 0) {
+				fprintf(stderr, "Error: Invalid date format '%s'. Use MM-DD-YYYY\n", argv[i + 1]);
+				return -1;
+			}
+			
+			args->mode = MODE_DATE;
+			args->target_year = args->target_date.tm_year + 1900;
+			i++; // Skip the date argument
+		} else if (strcmp(argv[i], "--year") == 0) {
+			if (i + 1 >= argc) {
+				fprintf(stderr, "Error: --year requires a year argument\n");
+				return -1;
+			}
+			
+			char *endptr;
+			long year = strtol(argv[i + 1], &endptr, 10);
+			
+			if (*endptr != '\0' || year < 1900 || year > 9999) {
+				fprintf(stderr, "Error: Invalid year '%s'\n", argv[i + 1]);
+				return -1;
+			}
+			
+			args->mode = MODE_YEAR;
+			args->target_year = (int)year;
+			
+			// Set target_date to January 1 of that year for calendar generation
+			memset(&args->target_date, 0, sizeof(struct tm));
+			args->target_date.tm_year = (int)(year - 1900);
+			args->target_date.tm_mon = 0;
+			args->target_date.tm_mday = 1;
+			mktime(&args->target_date);
+			
+			i++; // Skip the year argument
+		} else {
+			fprintf(stderr, "Unknown option: %s\n", argv[i]);
+			print_usage(argv[0]);
+			return -1;
+		}
+	}
+	
+	return 0;
+}

src/args.h

@@ -0,0 +1,26 @@
+#ifndef ARGS_H
+#define ARGS_H
+
+#include <time.h>
+
+typedef enum {
+	MODE_TODAY,
+	MODE_ALL,
+	MODE_DATE,
+	MODE_YEAR
+} OutputMode;
+
+typedef struct {
+	OutputMode mode;
+	struct tm target_date;
+	int target_year;
+} ProgramArgs;
+
+// Parse command line arguments
+// Returns 0 on success, -1 on error, 1 if help was shown
+int parse_args(int argc, char *argv[], ProgramArgs *args);
+
+// Print usage information
+void print_usage(const char *program_name);
+
+#endif // ARGS_H

src/main.c

@@ -1,17 +1,8 @@
 #include <stdio.h>
-#include <string.h>
 #include <time.h>
 #include "church_day.h"
 #include "builder.h"
-
-static void print_usage(const char *program_name) {
-	printf("Usage: %s [OPTIONS]\n", program_name);
-	printf("Calculate the church calendar for the current year.\n\n");
-	printf("Options:\n");
-	printf("  --all     Print all days in the liturgical year\n");
-	printf("  --help    Display this help message\n");
-	printf("\nWith no options, prints only today's liturgical day.\n");
-}
+#include "args.h"
 
 static int compare_dates(struct tm d1, struct tm d2) {
 	if (d1.tm_year != d2.tm_year) return d1.tm_year - d2.tm_year;
@@ -19,32 +10,7 @@ static int compare_dates(struct tm d1, struct tm d2) {
 	return d1.tm_mday - d2.tm_mday;
 }
 
-int main(int argc, char *argv[]) {
-	int print_all = 0;
-
-	// Parse arguments
-	for (int i = 1; i < argc; i++) {
-		if (strcmp(argv[i], "--all") == 0) {
-			print_all = 1;
-		} else if (strcmp(argv[i], "--help") == 0) {
-			print_usage(argv[0]);
-			return 0;
-		} else {
-			fprintf(stderr, "Unknown option: %s\n", argv[i]);
-			print_usage(argv[0]);
-			return 1;
-		}
-	}
-
-	time_t now = time(NULL);
-	struct tm *today = localtime(&now);
-
-	ChurchYear seasons = proper_of_seasons(*today);
-
-	if (print_all) {
-		// Print all days
-		for (size_t i = 0; i < seasons.count; i++) {
-			ChurchDay *day = &seasons.days[i];
+static void print_day(const ChurchDay *day) {
 	printf("%s, %s %d, %d - %s - %s in %s\n",
 		church_day_weekday_string(day),
 		church_day_month_name(day),
@@ -53,31 +19,51 @@ int main(int argc, char *argv[]) {
 		day->description,
 		day_class_to_string(day->class),
 		season_to_string(day->season));
+}
+
+int main(int argc, char *argv[]) {
+	ProgramArgs args;
+	int parse_result = parse_args(argc, argv, &args);
+	
+	if (parse_result == 1) {
+		// Help was shown
+		return 0;
+	} else if (parse_result == -1) {
+		// Error occurred
+		return 1;
 	}
-	} else {
-		// Print only today
+
+	ChurchYear seasons = proper_of_seasons(args.target_date);
+
+	switch (args.mode) {
+		case MODE_ALL:
+		case MODE_YEAR:
+			// Print all days
+			for (size_t i = 0; i < seasons.count; i++) {
+				print_day(&seasons.days[i]);
+			}
+			break;
+
+		case MODE_TODAY:
+		case MODE_DATE: {
+			// Print only the specified day
 			ChurchDay *found = NULL;
 			for (size_t i = 0; i < seasons.count; i++) {
-			if (compare_dates(seasons.days[i].date, *today) == 0) {
+				if (compare_dates(seasons.days[i].date, args.target_date) == 0) {
 					found = &seasons.days[i];
 					break;
 				}
 			}
 
 			if (found) {
-			printf("%s, %s %d, %d - %s - %s in %s\n",
-				church_day_weekday_string(found),
-				church_day_month_name(found),
-				found->date.tm_mday,
-				found->date.tm_year + 1900,
-				found->description,
-				day_class_to_string(found->class),
-				season_to_string(found->season));
+				print_day(found);
 			} else {
-			fprintf(stderr, "Could not find today's date in the liturgical calendar.\n");
+				fprintf(stderr, "Could not find the specified date in the liturgical calendar.\n");
 				church_year_free(&seasons);
 				return 1;
 			}
+			break;
+		}
 	}
 
 	church_year_free(&seasons);