import type { Round } from "./abi.js";
import { config } from "./config.js";

export type Side = "bull" | "bear" | null;

export function outcome(r: Round): "bull" | "bear" | "tie" | "pending" {
  if (!r.oracleCalled || r.closePrice === 0n) return "pending";
  if (r.closePrice === r.lockPrice) return "tie";
  return r.closePrice > r.lockPrice ? "bull" : "bear";
}

function momentumScore(history: Round[]): { bull: number; bear: number } {
  const outcomes = history.map(outcome).filter((o) => o === "bull" || o === "bear");
  if (outcomes.length < 3) return { bull: 0.5, bear: 0.5 };
  let bull = 0,
    bear = 0;
  const decay = 0.95;
  for (let i = outcomes.length - 1, w = 1; i >= 0 && i >= outcomes.length - config.lookbackRounds; i--, w *= decay) {
    if (outcomes[i] === "bull") bull += w;
    else bear += w;
  }
  const sum = bull + bear || 1;
  return { bull: bull / sum, bear: bear / sum };
}

function streakReversal(history: Round[]): Side {
  const outcomes = history.map(outcome).filter((o) => o === "bull" || o === "bear");
  if (outcomes.length < config.streakReversalThreshold) return null;
  const last = outcomes[outcomes.length - 1];
  let streak = 0;
  for (let i = outcomes.length - 1; i >= 0 && outcomes[i] === last; i--) streak++;
  if (streak >= config.streakReversalThreshold) return last === "bull" ? "bear" : "bull";
  return null;
}

export function decide(
  history: Round[],
  lastBetSide: Side,
  lastBetWon: boolean | null,
  roundsSinceBet: number
): { side: Side; edge: number } {
  if (history.length < 2) return { side: null, edge: 0 };
  const pending = history.filter((r) => outcome(r) === "pending");
  if (pending.length > 0) return { side: null, edge: 0 };
  const closed = history.filter((r) => r.oracleCalled && r.closePrice !== 0n);
  if (closed.length < 2) return { side: null, edge: 0 };

  if (lastBetWon === false && config.cooldownRoundsAfterLoss > 0 && roundsSinceBet < config.cooldownRoundsAfterLoss)
    return { side: null, edge: 0 };

  const rev = streakReversal(closed);
  if (rev !== null) {
    const edge = 0.52 + Math.min(0.08, closed.length * 0.002);
    return { side: rev, edge };
  }

  const { bull, bear } = momentumScore(closed);
  const rawEdge = Math.max(bull, bear);
  if (rawEdge < config.minEdgeScore) return { side: null, edge: rawEdge };
  const side: Side = bull >= bear ? "bull" : "bear";
  const edge = side === "bull" ? bull : bear;
  return { side, edge };
}