fix: encode timestamps correctly in cpp implementation (#7)

README.md

@@ -29,6 +29,8 @@
 
 Create and transform ULIDs
 
+This library will use the CPP implementation from https://github.com/suyash/ulid if cython is available, and will fallback to pure python if it is not.
+
 ## Example
 
 ```python

pyproject.toml

@@ -31,6 +31,8 @@ python = "^3.10"
 [tool.poetry.group.dev.dependencies]
 pytest = "^7.0"
 pytest-cov = "^3.0"
+Cython = "^0.29.32"
+setuptools = "^65.4.1"
 
 [tool.semantic_release]
 branch = "main"

src/ulid_transform/_ulid_impl.pyx

@@ -17,4 +17,6 @@ def _ulid_at_time(time: float) -> str:
     return _cpp_ulid_at_time(time).decode("ascii")
 
 def _ulid_to_bytes(ulid_str: str) -> bytes:
+    if len(ulid_str) != 26:
+        raise ValueError("ULID must be 26 characters")
     return _cpp_ulid_to_bytes(ulid_str.encode("ascii"))

src/ulid_transform/ulid_impl.py

@@ -4,7 +4,7 @@
 
 # From https://github.com/ahawker/ulid/blob/06289583e9de4286b4d80b4ad000d137816502ca/ulid/base32.py#L102
 #: Array that maps encoded string char byte values to enable O(1) lookups.
-DECODE = array.array(
+_DECODE = array.array(
     "B",
     (
         0xFF,
@@ -347,7 +347,7 @@ def ulid_to_bytes(value: str) -> bytes:
     if len(value) != 26:
         raise ValueError("ULID must be 26 characters")
     encoded = value.encode("ascii")
-    decoding = DECODE
+    decoding = _DECODE
     return bytes(
         (
             ((decoding[encoded[0]] << 5) | decoding[encoded[1]]) & 0xFF,

src/ulid_transform/ulid_wrapper.cpp

@@ -1,27 +1,25 @@
-#include "ulid.hh"
 #include "ulid_wrapper.h"
-#include <chrono>
+#include "ulid.hh"
 
 using namespace std;
 
-
 std::string _cpp_ulid() {
-    ulid::ULID ulid;
-    ulid::EncodeNowRand(ulid);
-    return ulid::Marshal(ulid);
+  ulid::ULID ulid;
+  ulid::EncodeNowRand(ulid);
+  return ulid::Marshal(ulid);
 }
 
-std::string _cpp_ulid_at_time(double timestamp) {
-    const auto encoded_time = chrono::system_clock::to_time_t(chrono::system_clock::time_point(chrono::duration_cast<chrono::seconds>(chrono::duration<double>(timestamp))));
-    ulid::ULID ulid;
-    ulid::EncodeTime(encoded_time, ulid);
-    ulid::EncodeEntropyRand(ulid);
-    return ulid::Marshal(ulid);
+std::string _cpp_ulid_at_time(double epoch_time) {
+  time_t encoded_time = static_cast<time_t>(epoch_time*1000);
+  ulid::ULID ulid;
+  ulid::EncodeTime(encoded_time, ulid);
+  ulid::EncodeEntropyRand(ulid);
+  return ulid::Marshal(ulid);
 }
 
 std::string _cpp_ulid_to_bytes(std::string ulid_string) {
-    ulid::ULID ulid = ulid::Unmarshal(ulid_string.c_str());
-    std::vector<uint8_t> data = ulid::MarshalBinary(ulid);
-    std::string str(reinterpret_cast<char*>(data.data()), data.size());
-    return str;
+  ulid::ULID ulid = ulid::Unmarshal(ulid_string.c_str());
+  std::vector<uint8_t> data = ulid::MarshalBinary(ulid);
+  std::string str(reinterpret_cast<char *>(data.data()), data.size());
+  return str;
 }

tests/test_init.py

@@ -35,6 +35,11 @@ def test_ulid_to_bytes_2():
     )
 
 
+def test_timestamp_string():
+    ulid = ulid_at_time(1677627631.2127638)
+    assert ulid[:10] == "01GTD6C9KC"
+
+
 def test_timestamp():
     now = time.time()
     ulid = ulid_at_time(now)