From c83c652b3761e5300841984c0bc333884a3680f1 Mon Sep 17 00:00:00 2001
From: Abdelrahman Said <said.abdelrahman@flawlessai.com>
Date: Sat, 22 Mar 2025 02:27:59 +0000
Subject: [PATCH] Add UUIDv4 generator

---
 src/uuid/uuid.c      | 59 ++++++++++++++++++++++++++++++++++++++++++++
 src/uuid/uuid.h      | 34 +++++++++++++++++++++++++
 src/uuid/wapp_uuid.c |  8 ++++++
 src/uuid/wapp_uuid.h |  9 +++++++
 src/wapp.c           |  1 +
 src/wapp.h           |  1 +
 6 files changed, 112 insertions(+)
 create mode 100644 src/uuid/uuid.c
 create mode 100644 src/uuid/uuid.h
 create mode 100644 src/uuid/wapp_uuid.c
 create mode 100644 src/uuid/wapp_uuid.h

diff --git a/src/uuid/uuid.c b/src/uuid/uuid.c
new file mode 100644
index 0000000..431615d
--- /dev/null
+++ b/src/uuid/uuid.c
@@ -0,0 +1,59 @@
+#include "uuid.h"
+#include "../common/aliases/aliases.h"
+#include "../core/strings/str8/str8.h"
+#include "../prng/xorshift/xorshift.h"
+#include <stdbool.h>
+#include <inttypes.h>
+
+#define UUID_STR_FORMAT ("%.8" PRIx64 "-%.4" PRIx64 "-%.4" PRIx64 "-%.4" PRIx64 "-%.12" PRIx64)
+
+typedef struct uuid4 UUID4;
+struct uuid4 {
+  u64 high;
+  u64 low;
+};
+
+internal UUID4 generate_uuid4(void);
+internal void  uuid4_to_uuid(const UUID4* uuid4, UUID *uuid);
+
+UUID *wapp_uuid_init_uuid4(UUID *uuid) {
+	if (!uuid) {
+		goto RETURN_INIT_UUID4;
+	}
+
+  UUID4 uuid4 = generate_uuid4();
+  uuid4_to_uuid(&uuid4, uuid);
+
+RETURN_INIT_UUID4:
+	return uuid;
+}
+
+internal UUID4 generate_uuid4(void) {
+  persistent XOR256State state = {0};
+  persistent bool initialised = false;
+
+  if (!initialised) {
+    initialised = true;
+    state       = wapp_prng_xorshift_init_state();
+  }
+
+  UUID4 uuid = (UUID4){
+    .high = wapp_prng_xorshift_256(&state),
+    .low  = wapp_prng_xorshift_256(&state),
+  };
+
+  uuid.high = (uuid.high & 0xffffffffffff0fff) | 0x0000000000004000;
+  uuid.low  = (uuid.low  & 0x3fffffffffffffff) | 0x8000000000000000;
+
+  return uuid;
+}
+
+internal void uuid4_to_uuid(const UUID4* uuid4, UUID *uuid) {
+  u64 grp1 = uuid4->high >> 32;
+  u64 grp2 = (uuid4->high << 32) >> 48;
+  u64 grp3 = (uuid4->high << 48) >> 48;
+  u64 grp4 = uuid4->low >> 48;
+  u64 grp5 = (uuid4->low << 16) >> 16;
+
+  wapp_str8_format(&(uuid->uuid), UUID_STR_FORMAT, grp1, grp2, grp3, grp4, grp5);
+}
diff --git a/src/uuid/uuid.h b/src/uuid/uuid.h
new file mode 100644
index 0000000..bfbec98
--- /dev/null
+++ b/src/uuid/uuid.h
@@ -0,0 +1,34 @@
+#ifndef UUID_H
+#define UUID_H
+
+#include "../common/aliases/aliases.h"
+#include "../core/strings/str8/str8.h"
+
+#ifdef __cplusplus
+BEGIN_C_LINKAGE
+#endif // __cplusplus
+
+#define UUID_BUF_LENGTH 48
+#define WAPP_UUID_SPEC WAPP_STR8_SPEC
+#define wapp_uuid_varg(UUID) wapp_str8_varg((UUID).uuid)
+
+typedef struct uuid UUID;
+struct uuid {
+  Str8 uuid;
+};
+
+#define wapp_uuid_gen_uuid4() *(wapp_uuid_init_uuid4(&wapp_uuid_create()))
+
+/* Low level UUID API */
+
+#define wapp_uuid_create() ((UUID){.uuid = wapp_str8_buf(UUID_BUF_LENGTH)})
+
+// Just returns the same pointer that was passed in with the UUID initialised.
+// If the pointer is NULL, it skips initialisation.
+UUID *wapp_uuid_init_uuid4(UUID *uuid);
+
+#ifdef __cplusplus
+END_C_LINKAGE
+#endif // __cplusplus
+
+#endif // !UUID_H
diff --git a/src/uuid/wapp_uuid.c b/src/uuid/wapp_uuid.c
new file mode 100644
index 0000000..7fa7ed4
--- /dev/null
+++ b/src/uuid/wapp_uuid.c
@@ -0,0 +1,8 @@
+#ifndef WAPP_UUID_C
+#define WAPP_UUID_C
+
+#include "uuid.c"
+#include "../core/wapp_core.c"
+#include "../prng/wapp_prng.c"
+
+#endif // !WAPP_UUID_C
diff --git a/src/uuid/wapp_uuid.h b/src/uuid/wapp_uuid.h
new file mode 100644
index 0000000..094ccd2
--- /dev/null
+++ b/src/uuid/wapp_uuid.h
@@ -0,0 +1,9 @@
+#ifndef WAPP_UUID_H
+#define WAPP_UUID_H
+
+#include "uuid.h"
+#include "../common/wapp_common.h"
+#include "../core/wapp_core.h"
+#include "../prng/wapp_prng.h"
+
+#endif // !WAPP_UUID_H
diff --git a/src/wapp.c b/src/wapp.c
index 16d148e..1459e5d 100644
--- a/src/wapp.c
+++ b/src/wapp.c
@@ -4,6 +4,7 @@
 #include "wapp.h"
 #include "core/wapp_core.c"
 #include "prng/wapp_prng.c"
+#include "uuid/uuid.c"
 #include "testing/wapp_testing.c"
 
 #endif // !WAPP_C
diff --git a/src/wapp.h b/src/wapp.h
index cddb106..68094dc 100644
--- a/src/wapp.h
+++ b/src/wapp.h
@@ -4,6 +4,7 @@
 #include "common/wapp_common.h"
 #include "core/wapp_core.h"
 #include "prng/wapp_prng.h"
+#include "uuid/wapp_uuid.h"
 #include "testing/wapp_testing.h"
 
 #endif // !WAPP_H