1 files changed, 97 insertions, 0 deletions
diff --git a/pre_commit/color.py b/pre_commit/color.py
new file mode 100644
index 0000000..5fa7042
--- /dev/null
+++ b/pre_commit/color.py
@@ -0,0 +1,97 @@
+import os
+import sys
+
+if sys.platform == 'win32':  # pragma: no cover (windows)
+    def _enable() -> None:
+        from ctypes import POINTER
+        from ctypes import windll
+        from ctypes import WinError
+        from ctypes import WINFUNCTYPE
+        from ctypes.wintypes import BOOL
+        from ctypes.wintypes import DWORD
+        from ctypes.wintypes import HANDLE
+
+        STD_OUTPUT_HANDLE = -11
+        ENABLE_VIRTUAL_TERMINAL_PROCESSING = 4
+
+        def bool_errcheck(result, func, args):
+            if not result:
+                raise WinError()
+            return args
+
+        GetStdHandle = WINFUNCTYPE(HANDLE, DWORD)(
+            ('GetStdHandle', windll.kernel32), ((1, 'nStdHandle'),),
+        )
+
+        GetConsoleMode = WINFUNCTYPE(BOOL, HANDLE, POINTER(DWORD))(
+            ('GetConsoleMode', windll.kernel32),
+            ((1, 'hConsoleHandle'), (2, 'lpMode')),
+        )
+        GetConsoleMode.errcheck = bool_errcheck
+
+        SetConsoleMode = WINFUNCTYPE(BOOL, HANDLE, DWORD)(
+            ('SetConsoleMode', windll.kernel32),
+            ((1, 'hConsoleHandle'), (1, 'dwMode')),
+        )
+        SetConsoleMode.errcheck = bool_errcheck
+
+        # As of Windows 10, the Windows console supports (some) ANSI escape
+        # sequences, but it needs to be enabled using `SetConsoleMode` first.
+        #
+        # More info on the escape sequences supported:
+        # https://msdn.microsoft.com/en-us/library/windows/desktop/mt638032(v=vs.85).aspx
+        stdout = GetStdHandle(STD_OUTPUT_HANDLE)
+        flags = GetConsoleMode(stdout)
+        SetConsoleMode(stdout, flags | ENABLE_VIRTUAL_TERMINAL_PROCESSING)
+
+    try:
+        _enable()
+    except OSError:
+        terminal_supports_color = False
+    else:
+        terminal_supports_color = True
+else:  # pragma: win32 no cover
+    terminal_supports_color = True
+
+RED = '\033[41m'
+GREEN = '\033[42m'
+YELLOW = '\033[43;30m'
+TURQUOISE = '\033[46;30m'
+SUBTLE = '\033[2m'
+NORMAL = '\033[m'
+
+
+def format_color(text: str, color: str, use_color_setting: bool) -> str:
+    """Format text with color.
+
+    Args:
+        text - Text to be formatted with color if `use_color`
+        color - The color start string
+        use_color_setting - Whether or not to color
+    """
+    if use_color_setting:
+        return f'{color}{text}{NORMAL}'
+    else:
+        return text
+
+
+COLOR_CHOICES = ('auto', 'always', 'never')
+
+
+def use_color(setting: str) -> bool:
+    """Choose whether to use color based on the command argument.
+
+    Args:
+        setting - Either `auto`, `always`, or `never`
+    """
+    if setting not in COLOR_CHOICES:
+        raise ValueError(setting)
+
+    return (
+        setting == 'always' or (
+            setting == 'auto' and
+            sys.stdout.isatty() and
+            terminal_supports_color and
+            os.getenv('TERM') != 'dumb'
+        )
+    )