From 6187d80144f1b029853fff8e74cc5dd4115dd349 Mon Sep 17 00:00:00 2001
From: Deepak Cherian <dcherian@users.noreply.github.com>
Date: Fri, 9 Feb 2024 19:57:32 -0700
Subject: [PATCH] Fix negative slicing of Zarr arrays (#8674)

* Fix negative slicing of Zarr arrays

Closes #8252
Closes #3921

* Cleanup
---
 doc/whats-new.rst       |  2 ++
 xarray/backends/zarr.py | 22 +++++++++++++---------
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/doc/whats-new.rst b/doc/whats-new.rst
index b2c4a0b5257..d51b5da2a88 100644
--- a/doc/whats-new.rst
+++ b/doc/whats-new.rst
@@ -59,6 +59,8 @@ Bug fixes
   By `Tom Nicholas <https://github.com/TomNicholas>`_.
 - Ensure :py:meth:`DataArray.unstack` works when wrapping array API-compliant classes. (:issue:`8666`, :pull:`8668`)
   By `Tom Nicholas <https://github.com/TomNicholas>`_.
+- Fix negative slicing of Zarr arrays without dask installed. (:issue:`8252`)
+  By `Deepak Cherian <https://github.com/dcherian>`_.
 - Preserve chunks when writing time-like variables to zarr by enabling lazy CF
   encoding of time-like variables (:issue:`7132`, :issue:`8230`, :issue:`8432`,
   :pull:`8575`). By `Spencer Clark <https://github.com/spencerkclark>`_ and
diff --git a/xarray/backends/zarr.py b/xarray/backends/zarr.py
index 469bbf4c339..8f9040477d9 100644
--- a/xarray/backends/zarr.py
+++ b/xarray/backends/zarr.py
@@ -86,19 +86,23 @@ def get_array(self):
     def _oindex(self, key):
         return self._array.oindex[key]
 
+    def _vindex(self, key):
+        return self._array.vindex[key]
+
+    def _getitem(self, key):
+        return self._array[key]
+
     def __getitem__(self, key):
         array = self._array
         if isinstance(key, indexing.BasicIndexer):
-            return array[key.tuple]
+            method = self._getitem
         elif isinstance(key, indexing.VectorizedIndexer):
-            return array.vindex[
-                indexing._arrayize_vectorized_indexer(key, self.shape).tuple
-            ]
-        else:
-            assert isinstance(key, indexing.OuterIndexer)
-            return indexing.explicit_indexing_adapter(
-                key, array.shape, indexing.IndexingSupport.VECTORIZED, self._oindex
-            )
+            method = self._vindex
+        elif isinstance(key, indexing.OuterIndexer):
+            method = self._oindex
+        return indexing.explicit_indexing_adapter(
+            key, array.shape, indexing.IndexingSupport.VECTORIZED, method
+        )
 
         # if self.ndim == 0:
         # could possibly have a work-around for 0d data here