src/lib/spark/engine.ts

import type { DebateState, DebateAction } from "./types";

export function createInitialDebateState(): DebateState {
  return {
    phase: "idle",
    debateId: null,
    config: null,
    topicOptions: [],
    selectedTopic: null,
    myVote: null,
    opponentVoted: false,
    currentRound: 0,
    rounds: [],
    currentOpener: "player1",
    currentOpeningArg: "",
    myArgument: "",
    momentum: 0,
    verdict: null,
    eloChange: 0,
    challengeResult: null,
  };
}

export function debateReducer(state: DebateState, action: DebateAction): DebateState {
  switch (action.type) {
    case "SET_CONFIG":
      return { ...state, phase: "config", config: action.config };

    case "SET_TOPICS":
      return { ...state, phase: "topic-select", topicOptions: action.topics };

    case "ADD_TOPIC":
      return { ...state, topicOptions: [...state.topicOptions, action.topic] };

    case "VOTE_TOPIC":
      return { ...state, myVote: action.topicId };

    case "OPPONENT_VOTED":
      return { ...state, opponentVoted: true };

    case "SELECT_TOPIC":
      return {
        ...state,
        phase: "round-open",
        selectedTopic: action.topic,
        currentRound: 1,
        currentOpener: "player1",
        currentOpeningArg: "",
        myArgument: "",
      };

    case "START_ROUND":
      return {
        ...state,
        phase: "round-open",
        currentRound: state.currentRound + 1,
        currentOpener: state.currentOpener === "player1" ? "player2" : "player1",
        currentOpeningArg: "",
        myArgument: "",
      };

    case "SET_OPENING_ARG":
      return {
        ...state,
        phase: "round-rebuttal",
        currentOpeningArg: action.argument,
        myArgument: "",
      };

    case "START_REBUTTAL":
      return { ...state, phase: "round-rebuttal" };

    case "UPDATE_ARGUMENT":
      return { ...state, myArgument: action.text };

    case "COMPLETE_ROUND":
      return {
        ...state,
        phase: "commentary",
        rounds: [...state.rounds, action.round],
      };

    case "SET_COMMENTARY": {
      const lastRound = state.rounds[state.rounds.length - 1];
      if (!lastRound) return state;
      const updatedRound = { ...lastRound, commentary: action.commentary };
      return {
        ...state,
        rounds: [...state.rounds.slice(0, -1), updatedRound],
        momentum: state.momentum + action.commentary.momentum,
      };
    }

    case "START_JUDGING":
      return { ...state, phase: "judging" };

    case "SET_VERDICT":
      return {
        ...state,
        phase: "verdict",
        verdict: action.verdict,
        eloChange: action.eloChange,
      };

    case "START_CHALLENGE":
      return { ...state, phase: "challenge" };

    case "SET_CHALLENGE_RESULT":
      return {
        ...state,
        phase: "verdict",
        challengeResult: action.result,
        verdict: action.result.newVerdict ?? state.verdict,
        eloChange: action.newEloChange,
      };

    case "FINISH":
      return { ...state, phase: "done" };

    case "RESET":
      return createInitialDebateState();

    default:
      return state;
  }
}