From c10f7e732307f77a7652189abecbae06490cf19a Mon Sep 17 00:00:00 2001
From: Dylan Araps <dylan.araps@gmail.com>
Date: Sat, 31 Mar 2018 13:28:11 +1100
Subject: [PATCH] backend: Error handling

---
 pywal/backends/colorthief.py | 8 +++++++-
 pywal/backends/colorz.py     | 7 +++++++
 pywal/backends/wal.py        | 4 ++--
 pywal/colors.py              | 1 +
 4 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/pywal/backends/colorthief.py b/pywal/backends/colorthief.py
index d223431..be8a3f1 100644
--- a/pywal/backends/colorthief.py
+++ b/pywal/backends/colorthief.py
@@ -3,7 +3,13 @@ Generate a colorscheme using ColorThief.
 """
 import sys
 
-from colorthief import ColorThief
+try:
+    from colorthief import ColorThief
+
+except ImportError:
+    print("Error: ColorThief wasn't found on your system.",
+          "Try another backend. (wal --backend)")
+    sys.exit(1)
 
 from .. import util
 
diff --git a/pywal/backends/colorz.py b/pywal/backends/colorz.py
index e67a8c8..5884e54 100644
--- a/pywal/backends/colorz.py
+++ b/pywal/backends/colorz.py
@@ -1,7 +1,9 @@
 """
 Generate a colorscheme using Colorz.
 """
+import shutil
 import subprocess
+import sys
 
 from .. import util
 
@@ -40,6 +42,11 @@ def adjust(colors, light):
 
 def get(img, light=False):
     """Get colorscheme."""
+    if not shutil.which("colorz"):
+        print("Error: Colorz wasn't found on your system.",
+              "Try another backend. (wal --backend)")
+        sys.exit(1)
+
     colors = gen_colors(img)
     colors = [color.decode('UTF-8').split()[0] for color in colors]
     return adjust(colors, light)
diff --git a/pywal/backends/wal.py b/pywal/backends/wal.py
index af955a4..71cd7e4 100644
--- a/pywal/backends/wal.py
+++ b/pywal/backends/wal.py
@@ -26,8 +26,8 @@ def has_im():
     elif shutil.which("convert"):
         return ["convert"]
 
-    print("error: imagemagick not found, exiting...\n"
-          "error: wal requires imagemagick to function.")
+    print("Error: ImageMagick wasn't found on your system.",
+          "Try another backend. (wal --backend)")
     sys.exit(1)
 
 
diff --git a/pywal/colors.py b/pywal/colors.py
index 7611826..d169c00 100644
--- a/pywal/colors.py
+++ b/pywal/colors.py
@@ -3,6 +3,7 @@ Generate a palette using various backends.
 """
 import os
 import re
+import shutil
 import sys
 
 from . import backends