From 6df9b4af61df97da3ee20c377a8c08bd6dfd2352 Mon Sep 17 00:00:00 2001
From: Darren Eberly <darren.eberly@gmail.com>
Date: Sun, 21 Feb 2021 15:40:44 -0500
Subject: [PATCH] Make zstd optional

---
 pytiled_parser/layer.py | 14 +++++++++++++-
 setup.cfg               |  4 +++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/pytiled_parser/layer.py b/pytiled_parser/layer.py
index 1fdefc0..c155cdf 100644
--- a/pytiled_parser/layer.py
+++ b/pytiled_parser/layer.py
@@ -10,8 +10,9 @@ See:
 
 import base64
 import gzip
+import importlib.util
+import sys
 import zlib
-import zstd
 from pathlib import Path
 from typing import Any, Callable, List, Optional, Union
 from typing import cast as type_cast
@@ -24,6 +25,12 @@ from . import tiled_object
 from .common_types import Color, OrderedPair, Size
 from .util import parse_color
 
+zstd_spec = importlib.util.find_spec("zstd")
+if zstd_spec:
+    import zstd  # pylint: disable=import-outside-toplevel
+else:
+    zstd = None  # pylint: disable=invalid-name
+
 
 @attr.s(auto_attribs=True, kw_only=True)
 class Layer:
@@ -244,6 +251,11 @@ def _decode_tile_layer_data(
         unzipped_data = zlib.decompress(unencoded_data)
     elif compression == "gzip":
         unzipped_data = gzip.decompress(unencoded_data)
+    elif compression == "zstd" and zstd is None:
+        raise ValueError(
+            "zstd compression support is not installed."
+            "To install use 'pip install pytiled-parser[zstd]'"
+        )
     elif compression == "zstd":
         unzipped_data = zstd.decompress(unencoded_data)
     else:
diff --git a/setup.cfg b/setup.cfg
index 2f55dcd..eafc65f 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -28,7 +28,6 @@ setup_requires =
   setuptools >= 40.6
   pip >= 10
 install_requires =
-  zstd == 1.4.8.1
   attrs
   typing-extensions
 
@@ -38,6 +37,9 @@ include =
   pytiled_parser.*
 
 [options.extras_require]
+zstd =
+  zstd == 1.4.8.1
+
 dev =
   pytest
   pytest-cov