Port EscapeLeadingWhitespace.

Author: nedtwigg

python/selfie-lib/selfie_lib/EscapeLeadingWhitespace.py

@@ -2,11 +2,56 @@
 
 
 class EscapeLeadingWhitespace(Enum):
+    ALWAYS = auto()
     NEVER = auto()
+    ONLY_ON_SPACE = auto()
+    ONLY_ON_TAB = auto()
 
-    def escape_line(self, line: str, space: str, tab: str) -> str:  # noqa: ARG002
-        return line
+    def escape_line(self, line: str, space: str, tab: str) -> str:
+        if line.startswith(" "):
+            if (
+                self == EscapeLeadingWhitespace.ALWAYS
+                or self == EscapeLeadingWhitespace.ONLY_ON_SPACE
+            ):
+                return f"{space}{line[1:]}"
+            else:
+                return line
+        elif line.startswith("\t"):
+            if (
+                self == EscapeLeadingWhitespace.ALWAYS
+                or self == EscapeLeadingWhitespace.ONLY_ON_TAB
+            ):
+                return f"{tab}{line[1:]}"
+            else:
+                return line
+        else:
+            return line
 
-    @staticmethod
-    def appropriate_for(file_content: str) -> "EscapeLeadingWhitespace":  # noqa: ARG004
-        return EscapeLeadingWhitespace.NEVER
+    @classmethod
+    def appropriate_for(cls, file_content: str) -> "EscapeLeadingWhitespace":
+        MIXED = "m"
+        common_whitespace = None
+
+        for line in file_content.splitlines():
+            whitespace = "".join(c for c in line if c.isspace())
+            if not whitespace:
+                continue
+            elif all(c == " " for c in whitespace):
+                whitespace = " "
+            elif all(c == "\t" for c in whitespace):
+                whitespace = "\t"
+            else:
+                whitespace = MIXED
+
+            if common_whitespace is None:
+                common_whitespace = whitespace
+            elif common_whitespace != whitespace:
+                common_whitespace = MIXED
+                break
+
+        if common_whitespace == " ":
+            return cls.ONLY_ON_TAB
+        elif common_whitespace == "\t":
+            return cls.ONLY_ON_SPACE
+        else:
+            return cls.ALWAYS