feat: Construct ranked hand with description

Refactors rank test functions to retern details required for
description, then return RankedHand from rank_hand function.

3 files changed, 129 insertions, 48 deletions

diff --git a/poker/rank/__init__.py b/poker/rank/__init__.py
index e69de29..c8700f9 100644
--- a/poker/rank/__init__.py
+++ b/poker/rank/__init__.py
@@ -0,0 +1,3 @@
+from poker.rank.hands import rank_hand
+
+__all__ = ["rank_hand"]
diff --git a/poker/rank/descriptions.py b/poker/rank/descriptions.py
index e69de29..e7f367a 100644
--- a/poker/rank/descriptions.py
+++ b/poker/rank/descriptions.py
@@ -0,0 +1,14 @@
+from poker.constants import Rank
+
+DESCRIPTIONS = {
+    Rank.ROYAL_FLUSH: "royal flush: {suit}",
+    Rank.STRAIGHT_FLUSH: "straight flush: {high}-high {suit}",
+    Rank.FOUR_OF_A_KIND: "four of a kind: {value}",
+    Rank.FULL_HOUSE: "full house: {trips} over {pair}",
+    Rank.FLUSH: "flush: {suit}",
+    Rank.STRAIGHT: "straight: {high}-high",
+    Rank.THREE_OF_A_KIND: "three of a kind: {value}",
+    Rank.TWO_PAIR: "two pair: {high} and {low}",
+    Rank.PAIR: "pair: {value}",
+    Rank.HIGH_CARD: "high card: {value}",
+}
diff --git a/poker/rank/hands.py b/poker/rank/hands.py
index 8764ce9..6a81af5 100644
--- a/poker/rank/hands.py
+++ b/poker/rank/hands.py
@@ -1,5 +1,8 @@
+from typing import Optional, Union
+
 from poker.constants import Rank, Value
-from poker.models import Card, Hand
+from poker.models import Card, Hand, RankedHand
+from poker.rank.descriptions import DESCRIPTIONS
 
 
 def _is_flush(cards: list[Card]) -> bool:
@@ -7,104 +10,165 @@ def _is_flush(cards: list[Card]) -> bool:
     return len(set(card.suit for card in cards)) == 1
 
 
-def _is_straight(cards: list[Card]) -> bool:
-    """Calculate whether hand is a straight."""
+def _is_straight(cards: list[Card]) -> Optional[Value]:
+    """Calculate whether hand is a straight.
+
+    Arguments:
+        cards: List of cards in hand.
+
+    Returns:
+        High card if hand is a straight, None otherwise.
+    """
     card_values = sorted([card.value for card in cards])
 
     # If card values are not unique it is not a straight
     if len(set(card_values)) != len(card_values):
-        return False
+        return None
 
     # Check for a ace low straight
     if card_values == [Value.TWO, Value.THREE, Value.FOUR, Value.FIVE, Value.ACE]:
-        return True
+        return Value.FIVE
 
     # If all card differences are 1 it is a straight
     diffs = [second - first for first, second in zip(card_values[:-1], card_values[1:])]
     if set(diffs) == {1}:
-        return True
+        return max(cards).value
 
-    return False
+    return None
 
 
-def is_royal_flush(hand: Hand) -> bool:
+def royal_flush(hand: Hand) -> dict[str, Union[str, int]]:
     """Calculate whether hand a royal flush."""
     if not _is_flush(hand.cards):
-        return False
+        return {}
 
     values = [card.value for card in hand.cards]
-    return all(
+    _is = all(
         value in values
         for value in [Value.ACE, Value.KING, Value.QUEEN, Value.JACK, Value.TEN]
     )
+    if _is:
+        return {"suit": hand.cards[0].suit}
+
+    return {}
 
 
-def is_straight_flush(hand: Hand) -> bool:
+def straight_flush(hand: Hand) -> dict[str, Union[str, int]]:
     """Calculate whether hand a straight flush."""
-    return _is_straight(hand.cards) and _is_flush(hand.cards)
+    high = _is_straight(hand.cards)
+    if high is not None and _is_flush(hand.cards):
+        return {
+            "high": high,
+            "suit": hand.cards[0].suit,
+        }
 
+    return {}
 
-def is_four_of_a_kind(hand: Hand) -> bool:
+
+def four_of_a_kind(hand: Hand) -> dict[str, Union[str, int]]:
     """Calculate whether hand has four of a kind."""
-    return hand.value_counts[0][1] == 4
+    if hand.value_counts[0][1] == 4:
+        return {"value": hand.value_counts[0][0]}
+
+    return {}
 
 
-def is_full_house(hand: Hand) -> bool:
+def full_house(hand: Hand) -> dict[str, Union[str, int]]:
     """Calculate whether hand is a full house."""
-    return hand.value_counts[0][1] == 3 and hand.value_counts[1][1] == 2
+    if hand.value_counts[0][1] == 3 and hand.value_counts[1][1] == 2:
+        return {
+            "trips": hand.value_counts[0][0],
+            "pair": hand.value_counts[1][0],
+        }
 
+    return {}
 
-def is_flush(hand: Hand) -> bool:
+
+def flush(hand: Hand) -> dict[str, Union[str, int]]:
     """Calculate whether hand is a flush."""
-    return _is_flush(hand.cards) and not _is_straight(hand.cards)
+    high = _is_straight(hand.cards)
+    if _is_flush(hand.cards) and high is None:
+        return {"suit": hand.cards[0].suit}
+
+    return {}
 
 
-def is_straight(hand: Hand) -> bool:
+def straight(hand: Hand) -> dict[str, Union[str, int]]:
     """Calculate whether hand is a flush."""
-    return _is_straight(hand.cards) and not _is_flush(hand.cards)
+    high = _is_straight(hand.cards)
+    if high is not None and not _is_flush(hand.cards):
+        return {"high": high}
 
+    return {}
 
-def is_three_of_a_kind(hand: Hand) -> bool:
+
+def three_of_a_kind(hand: Hand) -> dict[str, Union[str, int]]:
     """Calculate whether hand is a full house."""
-    return (
+    if (
         hand.value_counts[0][1] == 3
         and hand.value_counts[1][1] == 1
         and hand.value_counts[2][1] == 1
-    )
+    ):
+        return {"value": hand.value_counts[0][0]}
+
+    return {}
 
 
-def is_two_pair(hand: Hand) -> bool:
+def two_pair(hand: Hand) -> dict[str, Union[str, int]]:
     """Calculate whether hand is a two pair."""
-    return hand.value_counts[0][1] == 2 and hand.value_counts[1][1] == 2
+    if hand.value_counts[0][1] == 2 and hand.value_counts[1][1] == 2:
+        values = [hand.value_counts[0][0], hand.value_counts[1][0]]
+        return {
+            "high": max(values),
+            "low": min(values),
+        }
 
+    return {}
 
-def is_pair(hand: Hand) -> bool:
+
+def pair(hand: Hand) -> dict[str, Union[str, int]]:
     """Calculate whether hand is a pair."""
-    return hand.value_counts[0][1] == 2 and hand.value_counts[1][1] == 1
+    if hand.value_counts[0][1] == 2 and hand.value_counts[1][1] == 1:
+        return {"value": hand.value_counts[0][0]}
+
+    return {}
+
+
+def high_card(hand: Hand) -> dict[str, Union[str, int]]:
+    """Get high card."""
+    return {"value": max(hand.cards).value}
+
+
+_FUNCTIONS = {
+    Rank.ROYAL_FLUSH: royal_flush,
+    Rank.STRAIGHT_FLUSH: straight_flush,
+    Rank.FOUR_OF_A_KIND: four_of_a_kind,
+    Rank.FULL_HOUSE: full_house,
+    Rank.FLUSH: flush,
+    Rank.STRAIGHT: straight,
+    Rank.THREE_OF_A_KIND: three_of_a_kind,
+    Rank.TWO_PAIR: two_pair,
+    Rank.PAIR: pair,
+    Rank.HIGH_CARD: high_card,
+}
 
 
-def get_rank(hand: Hand) -> Rank:
+def rank_hand(hand: Hand) -> RankedHand:
     """Get hand rank.
 
     TODO: Use a factory pattern to avoid this huge flow control.
     """
-    if is_royal_flush(hand):
-        return Rank.ROYAL_FLUSH
-    elif is_straight_flush(hand):
-        return Rank.STRAIGHT_FLUSH
-    elif is_four_of_a_kind(hand):
-        return Rank.FOUR_OF_A_KIND
-    elif is_full_house(hand):
-        return Rank.FULL_HOUSE
-    elif is_flush(hand):
-        return Rank.FLUSH
-    elif is_straight(hand):
-        return Rank.STRAIGHT
-    elif is_three_of_a_kind(hand):
-        return Rank.THREE_OF_A_KIND
-    elif is_two_pair(hand):
-        return Rank.TWO_PAIR
-    elif is_pair(hand):
-        return Rank.PAIR
-    else:
-        return Rank.HIGH_CARD
+    out = None
+    for rank, func in _FUNCTIONS.items():
+        result = func(hand)
+        if result:
+            out = RankedHand(
+                cards=hand.cards,
+                rank=rank,
+                description=DESCRIPTIONS[rank].format(**result),
+            )
+
+    if out is None:
+        raise ValueError("No rank found.")
+
+    return out