1 files changed, 205 insertions, 0 deletions
diff --git a/internal/casino/craps_rules.go b/internal/casino/craps_rules.go
new file mode 100644
index 0000000..86aa9bb
--- /dev/null
+++ b/internal/casino/craps_rules.go
@@ -0,0 +1,205 @@
+package casino
+
+import "fmt"
+
+// CrapsConfig intentionally supports bank craps only. Other games must supply
+// their own outcome rules, not silently inherit bank-craps probabilities.
+type CrapsConfig struct {
+	Odds    int    `yaml:"odds,omitempty"` // 0 = 3-4-5x; positive = uniform Nx
+	Field12 int    `yaml:"field_12,omitempty"`
+	Variant string `yaml:"variant,omitempty"`
+}
+
+func (c CrapsConfig) Normalize() CrapsConfig {
+	if c.Field12 == 0 {
+		c.Field12 = 2
+	}
+	return c
+}
+func validateCraps(c TableConfig) error {
+	if c.Craps.Odds < 0 || c.Craps.Odds > 1000000 {
+		return fmt.Errorf("craps odds must be 0 (3-4-5x) or 1..1000000")
+	}
+	if c.Craps.Field12 != 0 && c.Craps.Field12 != 2 && c.Craps.Field12 != 3 {
+		return fmt.Errorf("craps field_12 must be 2 or 3")
+	}
+	if c.Craps.Variant != "" && c.Craps.Variant != "bank" {
+		return fmt.Errorf("only bank craps is implemented")
+	}
+	return nil
+}
+func crapsNumber(n int) bool { return n == 4 || n == 5 || n == 6 || n == 8 || n == 9 || n == 10 }
+func crapsTrueOdds(n int) (int, int) {
+	switch n {
+	case 4, 10:
+		return 2, 1
+	case 5, 9:
+		return 3, 2
+	default:
+		return 6, 5
+	}
+}
+func (c CrapsConfig) oddsLimit(n int, against bool) int {
+	if c.Odds > 0 {
+		return c.Odds
+	}
+	if against {
+		return 6
+	}
+	switch n {
+	case 4, 10:
+		return 3
+	case 5, 9:
+		return 4
+	default:
+		return 5
+	}
+}
+func (c TableConfig) CrapsRulesText() string {
+	r := c.Craps.Normalize()
+	odds := "3-4-5x (don't: 6x laid)"
+	if r.Odds > 0 {
+		odds = fmt.Sprintf("%dx", r.Odds)
+	}
+	return fmt.Sprintf("Bank Craps | Free odds %s | Field 12 pays %d:1\n"+
+		"bet <amount> on pass / dontpass / come / dontcome / field\n"+
+		"bet <amount> on place 6 / buy 4 / lay 10 / hard 8 / hop 2 3\n"+
+		"bet <amount> on seven / craps / eleven / ace-deuce / aces / boxcars / horn\n"+
+		"bet <amount> on odds pass / odds come 6 (also dontpass/dontcome)\n"+
+		"bet <amount> on fire / small / tall / all (before shooter's first roll only)\n"+
+		"Pass/come 1:1; don't bars 12. Place 4/10 9:5, 5/9 7:5, 6/8 7:6.\n"+
+		"Buy/lay true odds; 5%% commission on buy STAKE / lay WIN, rounded up, wins only.\n"+
+		"Field 2 pays 2:1; 3/4/9/10/11 pay 1:1. Hard 4/10 7:1; 6/8 9:1.\n"+
+		"Seven 4:1; craps 7:1; 11/3 15:1; 2/12 30:1; hop easy 15:1, hard 30:1.\n"+
+		"Horn splits equally across 2/3/11/12. Fire: 4/5/6 distinct made points pay 24/249/999:1.\n"+
+		"Small (2-6) / Tall (8-12) pay 34:1; All pays 175:1. Any 7 resets ATS.\n"+
+		"Place/buy/hard and come odds are OFF on come-out; lay and don't odds work.\n"+
+		"Exact payout units required; no fractional-credit rounding except commission.\n"+
+		"Solo: roll anytime. Multiplayer: 10 seconds to bet, then 60 seconds for the shooter.\n"+
+		"Bets remain open until the roll. Dice rotate on seven-out.\n"+
+		"autoroll: repeat every 3 seconds on your turn (multiplayer waits 10 seconds).\n"+
+		"unbet <target>: remove non-contract bets/odds; pass/come contracts stay.\n"+
+ "unbet all: return every optional bet and odds at once.\n"+
+		"stop cancels autoroll without leaving; in manual mode stop/sitout wait for bets.\n"+
+		"Disconnect forfeits live bets.\n"+
+		"Winning bets return stake and are removed (no automatic pressing).", odds, r.Field12)
+}
+
+// outcome returns resolved and profit numerator/denominator; -1 means loss.
+func crapsOutcome(kind string, n, a, b, point, field12 int) (bool, int, int) {
+	s := a + b
+	hard := a == b
+	switch kind {
+	case "pass", "come", "dontpass", "dontcome":
+		against := kind == "dontpass" || kind == "dontcome"
+		if n == 0 {
+			if against {
+				switch s {
+				case 2, 3:
+					return true, 1, 1
+				case 7, 11:
+					return true, -1, 1
+				case 12:
+					return true, 0, 1
+				}
+			} else {
+				switch s {
+				case 7, 11:
+					return true, 1, 1
+				case 2, 3, 12:
+					return true, -1, 1
+				}
+			}
+			return false, 0, 1
+		}
+		if s != 7 && s != n {
+			return false, 0, 1
+		}
+		if (s == n) != against {
+			return true, 1, 1
+		}
+		return true, -1, 1
+	case "place", "buy", "lay":
+		if point == 0 && kind != "lay" {
+			return false, 0, 1
+		}
+		if s != 7 && s != n {
+			return false, 0, 1
+		}
+		if (s == 7) != (kind == "lay") {
+			return true, -1, 1
+		}
+		x, y := crapsTrueOdds(n)
+		if kind == "lay" {
+			x, y = y, x
+		}
+		if kind == "place" {
+			switch n {
+			case 4, 10:
+				x, y = 9, 5
+			case 5, 9:
+				x, y = 7, 5
+			default:
+				x, y = 7, 6
+			}
+		}
+		return true, x, y
+	case "hard":
+		if point == 0 {
+			return false, 0, 1
+		}
+		if s == 7 || (s == n && !hard) {
+			return true, -1, 1
+		}
+		if s == n {
+			if n == 4 || n == 10 {
+				return true, 7, 1
+			}
+			return true, 9, 1
+		}
+		return false, 0, 1
+	case "field":
+		switch s {
+		case 2:
+			return true, 2, 1
+		case 12:
+			return true, field12, 1
+		case 3, 4, 9, 10, 11:
+			return true, 1, 1
+		}
+		return true, -1, 1
+	case "seven":
+		if s == 7 {
+			return true, 4, 1
+		}
+	case "craps":
+		if s == 2 || s == 3 || s == 12 {
+			return true, 7, 1
+		}
+	case "eleven", "ace-deuce":
+		if (kind == "eleven" && s == 11) || (kind == "ace-deuce" && s == 3) {
+			return true, 15, 1
+		}
+	case "aces", "boxcars":
+		if (kind == "aces" && s == 2) || (kind == "boxcars" && s == 12) {
+			return true, 30, 1
+		}
+	case "hop":
+		if a*10+b == n || b*10+a == n {
+			if hard {
+				return true, 30, 1
+			}
+			return true, 15, 1
+		}
+	case "horn":
+		switch s {
+		case 2, 12:
+			return true, 27, 4
+		case 3, 11:
+			return true, 3, 1
+		}
+	default:
+		return false, 0, 1
+	}
+	return true, -1, 1
+}