import { Bot } from '../bot/Bot';
import { describeAction } from '../rules/Action';
import { describeEvent } from '../rules/GameEvent';
import { PlayerId } from '../rules/GameState';
import { Match } from './Match';

export interface RunOptions {
    /** Safety net: a match this long means the rules have a cycle in them. */
    maxActions?: number;
    /** Collects a human-readable trace, for debugging a bad seed. */
    trace?: string[];
}

export interface RunResult {
    loser: PlayerId | null;
    actions: number;
    turns: number;
}

/**
 * Plays a match out between bots, with no engine and no clock. The soak test
 * leans on this; so does anyone reproducing a bug from a seed.
 *
 * Stops early and returns if it reaches a seat with no bot — that is how the
 * same driver can fast-forward a match that a human is also playing.
 */
export function runMatch(match: Match, bots: Record<PlayerId, Bot>, options: RunOptions = {}): RunResult {
    const maxActions = options.maxActions ?? 2000;
    let actions = 0;

    while (!match.finished) {
        const actor = match.currentActor;
        if (actor === null) break;

        const bot = bots[actor];
        if (!bot) break;

        const action = bot.decide(match.viewFor(actor));
        if (options.trace) {
            options.trace.push(describeAction(action));
        }
        const events = match.perform(action);
        if (options.trace) {
            for (const event of events) {
                options.trace.push(`  ${describeEvent(event)}`);
            }
        }

        actions += 1;
        if (actions > maxActions) {
            throw new Error(`Match did not finish within ${maxActions} actions`);
        }
    }

    return { loser: match.loser, actions, turns: match.state.turnNumber };
}