Better passport validation

aoc2020/day04/solution.py

@@ -10,6 +10,8 @@ def main() -> int:
 
 NoneString = typing.Optional[str]
 
+VALID_EYE_COLORS = ("amb", "blu", "brn", "gry", "grn", "hzl", "oth")
+
 
 class Passport:
     byr: NoneString = None
@@ -22,13 +24,68 @@ class Passport:
     pid: NoneString = None
 
     def is_valid(self) -> bool:
-        return all(
-            [
-                getattr(self, attr) is not None
-                for attr in ("byr", "ecl", "eyr", "hcl", "hgt", "iyr", "pid")
-            ]
+        return (
+            self._is_year_in_range(self.byr, range(1920, 2003))
+            and self._is_year_in_range(self.iyr, range(2010, 2021))
+            and self._is_year_in_range(self.eyr, range(2020, 2031))
+            and self._has_valid_height()
+            and self._has_valid_hair_color()
+            and self.ecl in VALID_EYE_COLORS
+            and self._has_valid_passport_id()
         )
 
+    def _has_valid_height(self) -> bool:
+        if self.hgt is None:
+            return False
+
+        height_value = 0
+
+        height_value_string = self.hgt.replace("cm", "").replace("in", "")
+        if not height_value_string.isdigit():
+            return False
+
+        height = int(height_value_string)
+
+        if self.hgt.endswith("cm") and height in range(150, 194):
+            return True
+        elif self.hgt.endswith("in") and height in range(59, 77):
+            return True
+
+        return False
+
+    def _has_valid_hair_color(self) -> bool:
+        if self.hcl is None:
+            return False
+
+        if not self.hcl.startswith("#"):
+            return False
+
+        hair_value = self.hcl.replace("#", "")
+        if len(hair_value) != 6:
+            return False
+
+        try:
+            _ = int(hair_value, 16)
+            return True
+        except ValueError:
+            return False
+
+    def _has_valid_passport_id(self) -> bool:
+        return (
+            self.pid is not None
+            and len(self.pid) == 9
+            and all([s.isdigit() for s in list(self.pid)])
+        )
+
+    def _is_year_in_range(self, value: NoneString, yr_range: range) -> bool:
+        if value is None:
+            return False
+        if len(value) != 4:
+            return False
+        if not value.isdigit():
+            return False
+        return int(value) in yr_range
+
 
 def _read_passports(
     instream: typing.BinaryIO,