From 35b868d0c12bc5f04c3c95c5b2a2e6e3b0d3b448 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9o=20LUDWIG?= <contact@theoludwig.fr>
Date: Thu, 12 Sep 2024 12:22:53 +0200
Subject: [PATCH] feat: add `string_pad_start`

---
 lib/string.c       | 24 ++++++++++++++++++++++++
 lib/string.h       | 12 ++++++++++++
 test/string_test.c | 19 +++++++++++++++++++
 test/string_test.h |  2 ++
 4 files changed, 57 insertions(+)

diff --git a/lib/string.c b/lib/string.c
index 653602b..c4da49d 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -407,3 +407,27 @@ size_t string_last_position_of(const string_t string, const char character) {
   }
   return position_found;
 }
+
+string_t string_pad_start(const string_t string, const string_t pad_string, size_t target_length) {
+  string_t result = malloc(sizeof(char) * (target_length + 1));
+  size_t initial_length = string_get_length(string);
+  size_t left_length = target_length - initial_length;
+  if (target_length <= initial_length) {
+    left_length = 0;
+  }
+  size_t pad_length = string_get_length(pad_string);
+  size_t count_pad_string = 0;
+  size_t index_initial_string = 0;
+  for (size_t index = 0; index < target_length; index++) {
+    if (index < left_length) {
+      size_t index_pad_string = count_pad_string % pad_length;
+      result[index] = pad_string[index_pad_string];
+      count_pad_string += 1;
+    } else {
+      result[index] = string[index_initial_string];
+      index_initial_string += 1;
+    }
+  }
+  result[target_length] = '\0';
+  return result;
+}
diff --git a/lib/string.h b/lib/string.h
index e4e2b00..895ad09 100644
--- a/lib/string.h
+++ b/lib/string.h
@@ -286,4 +286,16 @@ size_t string_position_of(const string_t string, const char character);
  */
 size_t string_last_position_of(const string_t string, const char character);
 
+/**
+ * @brief Pads a `string` with another `pad_string` (multiple times, if needed) until the resulting string reaches the `target_length`. The padding is applied from the start (left) of the string.
+ *
+ * @param string The string to pad.
+ * @param pad_string The string to pad the current string with, to the left.
+ * @param target_length
+ * @return string_t
+ * @example string_pad_start("hello", " ", 10) // "     hello"
+ * @since vTODO
+ */
+string_t string_pad_start(const string_t string, const string_t pad_string, size_t target_length);
+
 #endif
diff --git a/test/string_test.c b/test/string_test.c
index 3998a5d..0590b97 100644
--- a/test/string_test.c
+++ b/test/string_test.c
@@ -27,6 +27,7 @@ void string_test() {
   string_ends_with_test();
   string_position_of_test();
   string_last_position_of_test();
+  string_pad_start_test();
 }
 
 void string_get_length_test() {
@@ -303,3 +304,21 @@ void string_last_position_of_test() {
   assert(string_last_position_of("abcdef", 'f') == 6);
   assert(string_last_position_of("abcdef", 'g') == 0);
 }
+
+void string_pad_start_test() {
+  string_t result = string_pad_start("hello", "ab", 10);
+  assert(assert_string_equal(result, "ababahello"));
+  free(result);
+
+  result = string_pad_start("hello", "ab", 4);
+  assert(assert_string_equal(result, "hell"));
+  free(result);
+
+  result = string_pad_start("hello", "ab", 5);
+  assert(assert_string_equal(result, "hello"));
+  free(result);
+
+  result = string_pad_start("hello", "ab", 6);
+  assert(assert_string_equal(result, "ahello"));
+  free(result);
+}
diff --git a/test/string_test.h b/test/string_test.h
index c5109fc..f3e44b9 100644
--- a/test/string_test.h
+++ b/test/string_test.h
@@ -62,4 +62,6 @@ void string_position_of_test();
 
 void string_last_position_of_test();
 
+void string_pad_start_test();
+
 #endif