From de5e0f2eaea1ef46446937e2e052e1abbf1f3df5 Mon Sep 17 00:00:00 2001
From: Aki <please@ignore.pl>
Date: Tue, 18 Jun 2024 00:01:51 +0200
Subject: Use struct internally for handling the versions

---
 Makefile  |   3 +-
 datever.c | 126 +++++++++++++++++++++++++++++++++++++++++++++-----------------
 2 files changed, 93 insertions(+), 36 deletions(-)

diff --git a/Makefile b/Makefile
index 5a5f407..f48a6f7 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-CFLAGS=-Wall -Wextra -Wpedantic -O3
+CFLAGS=-Wall -Wextra -Wpedantic -O3 -std=c99 -D_POSIX_C_SOURCE=200809L
 CFLAGS+=`pkg-config --cflags libgit2`
 LDLIBS+=`pkg-config --libs libgit2`
 
@@ -10,4 +10,5 @@ clean:
 	rm -f datever
 
 
+.POSIX:
 .PHONY: all clean
diff --git a/datever.c b/datever.c
index a8c63df..626899b 100644
--- a/datever.c
+++ b/datever.c
@@ -1,11 +1,24 @@
 #include <stdio.h>
-#include <string.h>
 #include <time.h>
 
 #include <git2.h>
 
 
+struct datever
+{
+	int year;
+	int month;
+	int day;
+	int revision;
+};
+
+
 static int must(const char* msg, int err);
+static struct datever find_latest(git_repository* repo);
+static struct datever datever_init();
+static struct datever datever_from_time(time_t time);
+static int datever_is_valid(const struct datever* ver);
+static int datever_compare(const struct datever* lhs, const struct datever* rhs);
 
 
 int
@@ -14,52 +27,95 @@ main()
 	git_libgit2_init();
 	git_repository* repo = NULL;
 	must("open repository", git_repository_open_ext(&repo, NULL, GIT_REPOSITORY_OPEN_FROM_ENV, NULL));
+	const struct datever ver = find_latest(repo);
+	printf("%d%02d%02d.%d\n", ver.year, ver.month, ver.day, ver.revision);
+}
+
+
+/// If [[err]] is considered erroneous, print [[msg]] and the last libgit2 error to standard error and then terminate
+/// current process.
+int
+must(const char* const msg, const int err)
+{
+	if (0 > err) {
+		const git_error* const e = git_error_last();
+		if (NULL != msg)
+			dprintf(2, "%s: ", msg);
+		dprintf(2, "%s\n", e->message);
+		exit(1);
+	}
+	return err;
+}
+
+
+struct datever
+find_latest(git_repository* const repo)
+{
 	git_revwalk* walker = NULL;
 	must("walk revisions", git_revwalk_new(&walker, repo));
 	must("find HEAD", git_revwalk_push_head(walker));
 	git_oid oid;
-	char prev[37];
-	prev[0] = 0;
-	char date[37];
-	int count = 0;
+	git_commit* commit;
+	struct datever prev = datever_init();
+	struct datever ver = datever_init();
 	while (0 == git_revwalk_next(&oid, walker)) {
-		git_commit* commit;
 		must("find commit", git_commit_lookup(&commit, repo, &oid));
-		const git_time_t gt = git_commit_time(commit);
-		const struct tm* const tm = gmtime(&gt);
-		if (NULL == tm) {
-			perror("read time");
-			exit(1);
-		}
-		snprintf(
-			date,
-			37,
-			"%d%02d%02d",
-			tm->tm_year + 1900,
-			tm->tm_mon + 1,
-			tm->tm_mday);
-		if (0 != prev[0]) {
-			if (0 == strncmp(prev, date, 37))
-				count++;
-			else break;  // Last commit is not deallocated!
+		ver = datever_from_time(git_commit_time(commit));
+		if (datever_is_valid(&prev)) {
+			if (0 == datever_compare(&prev, &ver))
+				ver.revision++;
+			else break;
 		}
-		strcpy(prev, date);
+		prev = ver;
 		git_commit_free(commit);
 	}
-	printf("%s.%d\n", date, count + 1);
+	git_commit_free(commit);
+	return prev;
+}
+
+
+/// Initialize empty, and thus invalid, version.
+struct datever
+datever_init()
+{
+	return (struct datever){
+		.year = -1,
+		.month = -1,
+		.day = -1,
+		.revision = -1,
+	};
+}
+
+
+struct datever
+datever_from_time(const time_t time)
+{
+	const struct tm* tm = gmtime(&time);
+	return (struct datever){
+		.year = tm->tm_year + 1900,
+		.month = tm->tm_mon + 1,
+		.day = tm->tm_mday,
+		.revision = 1,
+	};
 }
 
 
-/// If [[err]] is considered erroneuos, print [[msg]] and the last libgit2 error to standard error and then terminate.
 int
-must(const char* msg, const int err)
+datever_is_valid(const struct datever* const ver)
 {
-	if (0 > err) {
-		const git_error* const e = git_error_last();
-		if (NULL != msg)
-			dprintf(2, "%s: ", msg);
-		dprintf(2, "%s\n", e->message);
-		exit(1);
-	}
-	return err;
+	return 0 <= ver->year && 0 <= ver->month && 0 <= ver->day && 0 <= ver->revision;
+}
+
+
+/// Compares two versions date-wise ignoring revision count. Returns similarly to strcmp(3).
+int
+datever_compare(const struct datever* const lhs, const struct datever* const rhs)
+{
+	if (lhs->year > rhs->year) return -1;
+	if (lhs->year < rhs->year) return 1;
+	if (lhs->month > rhs->month) return -1;
+	if (lhs->month < rhs->month) return 1;
+	if (lhs->day > rhs->day) return -1;
+	if (lhs->day < rhs->day) return 1;
+	return 0;
 }
-- 
cgit v1.1