From c7670d0ee314947f26bdc4bb9a23fc40f2c57445 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gonzalo=20Tornar=C3=ADa?= <tornaria@cmat.edu.uy>
Date: Sat, 25 Nov 2023 16:12:04 -0300
Subject: [PATCH] Do not fail when `java` is available but `jmol` is not.

If java is not available, sagemath will fallback to tachyon gracefully.

When java is available, sagemath will assume jmol is available
and error if not. This commit fixes the issue by implementing a
method `is_jmol_available()` to replace `is_jvm_available()`.
---
 src/sage/interfaces/jmoldata.py              | 44 +++++++++++++++++++-
 src/sage/plot/plot3d/base.pyx                |  2 +-
 src/sage/repl/rich_output/backend_ipython.py |  2 +-
 3 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/src/sage/interfaces/jmoldata.py b/src/sage/interfaces/jmoldata.py
index a68e53e2d85..55c07255b74 100644
--- a/src/sage/interfaces/jmoldata.py
+++ b/src/sage/interfaces/jmoldata.py
@@ -71,6 +71,47 @@ def is_jvm_available(self):
         java_version_number = int(re.sub(r'.*version "(0\.|1\.)?(\d*)[\s\S]*', r'\2', version, flags=re.S))
         return java_version_number >= 7
 
+    def jmolpath(self):
+        """
+        Return the path to the jar file.
+
+        EXAMPLES::
+
+            sage: from sage.interfaces.jmoldata import JmolData
+            sage: JData = JmolData()
+            sage: JData.jmolpath()
+            '.../JmolData.jar'
+
+        """
+        jmolpath = os.path.join(JMOL_DIR, "JmolData.jar")
+
+        if sys.platform == 'cygwin':
+            import cygwin
+            jmolpath = cygwin.cygpath(jmolpath, 'w')
+
+        return jmolpath
+
+    def is_jmol_available(self):
+        """
+        Returns True if jmol is available and False if not.
+
+        EXAMPLES:
+
+        Check that it returns a boolean::
+
+            sage: from sage.interfaces.jmoldata import JmolData
+            sage: JData = JmolData()
+            sage: type(JData.is_jmol_available())
+            <... 'bool'>
+        """
+        if not os.path.isfile(self.jmolpath()):
+            return False
+
+        if not self.is_jvm_available():
+            return False
+
+        return True
+
     def export_image(self,
         targetfile,
         datafile, #name (path) of data file Jmol can read or script file telling it what to read or load
@@ -154,12 +195,11 @@ def export_image(self,
             sage: archive.close()
         """
         # Set up paths, file names and scripts
-        jmolpath = os.path.join(JMOL_DIR, "JmolData.jar")
+        jmolpath = self.jmolpath()
         target_native = targetfile
 
         if sys.platform == 'cygwin':
             import cygwin
-            jmolpath = cygwin.cygpath(jmolpath, 'w')
             target_native = cygwin.cygpath(target_native, 'w')
             if datafile_cmd != 'script':
                 datafile = cygwin.cygpath(datafile, 'w')
diff --git a/src/sage/plot/plot3d/base.pyx b/src/sage/plot/plot3d/base.pyx
index 253f152130c..7588cde2e27 100644
--- a/src/sage/plot/plot3d/base.pyx
+++ b/src/sage/plot/plot3d/base.pyx
@@ -278,7 +278,7 @@ cdef class Graphics3d(SageObject):
         T.export_jmol(scene_zip, **opts)
         from sage.interfaces.jmoldata import JmolData
         jdata = JmolData()
-        if not jdata.is_jvm_available():
+        if not jdata.is_jmol_available():
             # We can only use JMol to generate preview if a jvm is installed
             from sage.repl.rich_output.output_graphics import OutputImagePng
             tachyon = self._rich_repr_tachyon(OutputImagePng, **opts)
diff --git a/src/sage/repl/rich_output/backend_ipython.py b/src/sage/repl/rich_output/backend_ipython.py
index 69e63b76d60..10ccdc0c2c8 100644
--- a/src/sage/repl/rich_output/backend_ipython.py
+++ b/src/sage/repl/rich_output/backend_ipython.py
@@ -369,7 +369,7 @@ def launch_jmol(self, output_jmol, plain_text):
         from sage.doctest import DOCTEST_MODE
         from sage.interfaces.jmoldata import JmolData
         jdata = JmolData()
-        if not jdata.is_jvm_available() and not DOCTEST_MODE:
+        if not jdata.is_jmol_available() and not DOCTEST_MODE:
             raise RuntimeError('jmol cannot run, no suitable java version found')
         launch_script = output_jmol.launch_script_filename()
         jmol_cmd = 'jmol'