From 1ff0fee1e8b00bd8585911191267834f745ecc09 Mon Sep 17 00:00:00 2001
From: Alexander Bock <mail@alexanderbock.eu>
Date: Thu, 11 Sep 2025 21:15:40 +0200
Subject: [PATCH] Add support for specifying the format string for the
 `openspace.time.SPICE()` function

---
 include/openspace/util/spicemanager.h |  3 +++
 include/openspace/util/time.h         |  7 +++++++
 src/util/spicemanager.cpp             | 18 +++++++++++++++++-
 src/util/time.cpp                     | 10 ++++++++++
 src/util/time_lua.inl                 | 13 +++++++++----
 5 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/include/openspace/util/spicemanager.h b/include/openspace/util/spicemanager.h
index 3128e5c4c4..e7c71f30ef 100644
--- a/include/openspace/util/spicemanager.h
+++ b/include/openspace/util/spicemanager.h
@@ -613,6 +613,9 @@ public:
 
     std::string dateFromEphemerisTime(double ephemerisTime, const char* format);
 
+    void dateFromEphemerisTime(double ephemerisTime, char* outBuf, int bufferSize,
+        const std::string& format = "YYYY MON DDTHR:MN:SC.### ::RND") const;
+
     /**
      * Returns the \p position of a \p target body relative to an \p observer in a
      * specific \p referenceFrame, optionally corrected for \p lightTime (planetary
diff --git a/include/openspace/util/time.h b/include/openspace/util/time.h
index e6fe1b581c..c2a4fd651f 100644
--- a/include/openspace/util/time.h
+++ b/include/openspace/util/time.h
@@ -136,6 +136,13 @@ public:
      */
     std::string_view UTC() const;
 
+    /**
+     * Returns the current time as a formatted date string. The date string can be
+     * formatted using the SPICE picture parameters as described in
+     * https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/timout_c.html
+     */
+    std::string_view string(const std::string& format) const;
+
     /**
      * Returns the current time as a ISO 8601 formatted, i.e YYYY-MM-DDThh:mm:ssZ.
      *
diff --git a/src/util/spicemanager.cpp b/src/util/spicemanager.cpp
index b53fa40b9c..c8f1d3c3e4 100644
--- a/src/util/spicemanager.cpp
+++ b/src/util/spicemanager.cpp
@@ -637,10 +637,26 @@ std::string SpiceManager::dateFromEphemerisTime(double ephemerisTime, const char
         et2utc_c(ephemerisTime, "C", SecondsPrecision, BufferSize, Buffer.data());
     }
 
-
     return std::string(Buffer.data());
 }
 
+void SpiceManager::dateFromEphemerisTime(double ephemerisTime, char* outBuf,
+                                         int bufferSize, const std::string& format) const
+{
+    timout_c(ephemerisTime, format.c_str(), bufferSize, outBuf);
+    if (failed_c()) {
+        throwSpiceError(std::format(
+            "Error converting ephemeris time '{}' to date with format '{}'",
+            ephemerisTime, format
+        ));
+    }
+    if (outBuf[0] == '*') {
+        // The conversion failed and we need to use et2utc
+        constexpr int SecondsPrecision = 3;
+        et2utc_c(ephemerisTime, "C", SecondsPrecision, bufferSize, outBuf);
+    }
+}
+
 glm::dvec3 SpiceManager::targetPosition(const std::string& target,
                                         const std::string& observer,
                                         const std::string& referenceFrame,
diff --git a/src/util/time.cpp b/src/util/time.cpp
index 5ae23792e6..3dcf06894f 100644
--- a/src/util/time.cpp
+++ b/src/util/time.cpp
@@ -121,6 +121,16 @@ std::string_view Time::UTC() const {
     return std::string_view(b);
 }
 
+std::string_view Time::string(const std::string& format) const {
+    char* b = reinterpret_cast<char*>(
+        global::memoryManager->TemporaryMemory.allocate(128)
+    );
+    std::memset(b, 0, 128);
+
+    SpiceManager::ref().dateFromEphemerisTime(_time, b, 128, format.c_str());
+    return std::string_view(b);
+}
+
 std::string_view Time::ISO8601() const {
     ZoneScoped;
 
diff --git a/src/util/time_lua.inl b/src/util/time_lua.inl
index 2dfb3a4daa..f8a6a00904 100644
--- a/src/util/time_lua.inl
+++ b/src/util/time_lua.inl
@@ -349,13 +349,18 @@ namespace {
 
 
 /**
- * Returns the current time as an date string of the form
- * (YYYY MON DDTHR:MN:SC.### ::RND) as returned by SPICE.
+ * Returns the current time as an date string. The format of the returned string can be
+ * adjusted by providing the format picture. The default picture that is used will be
+ * (YYYY MON DDTHR:MN:SC.### ::RND). See
+ * https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/timout_c.html
+ * for documentation on how the format string can be formatted
  *
  * \return The current time, in the format used by SPICE (YYYY MON DDTHR:MN:SC.### ::RND)
  */
-[[codegen::luawrap("SPICE")]] std::string currentTimeSpice() {
-    return std::string(openspace::global::timeManager->time().UTC());
+[[codegen::luawrap("SPICE")]] std::string currentTimeSpice(
+                                    std::string format = "YYYY MON DDTHR:MN:SC.### ::RND")
+{
+    return std::string(openspace::global::timeManager->time().string(format));
 }
 
 /**