import { StoryHistoryRole, StoryMoment, StoryOption } from '../types';
import { sanitizePromptNarrativeText } from './narrativeLanguage';

const RECENT_ROUND_COUNT = 3;
const MAX_SUMMARY_GROUPS = 6;
const ACTION_SUMMARY_LIMIT = 24;
const RESULT_SUMMARY_LIMIT = 80;

type StoryHistoryRound = {
  actionText: string | null;
  resultTexts: string[];
};

export interface StoryPromptHistory {
  recentOriginalRounds: string[];
  previousSummary: string | null;
}

function normalizeWhitespace(text: string) {
  return text.replace(/\s+/g, ' ').trim();
}

function truncateText(text: string, limit: number) {
  if (text.length <= limit) return text;
  return `${text.slice(0, Math.max(0, limit - 1)).trimEnd()}...`;
}

function hasRoundContent(round: StoryHistoryRound) {
  return Boolean(round.actionText) || round.resultTexts.length > 0;
}

function resolveHistoryRole(entry: StoryMoment, index: number): StoryHistoryRole {
  if (entry.historyRole) {
    return entry.historyRole;
  }

  return index % 2 === 0 ? 'action' : 'result';
}

function buildStoryRounds(history: StoryMoment[]): StoryHistoryRound[] {
  const rounds: StoryHistoryRound[] = [];
  let currentRound: StoryHistoryRound | null = null;

  for (const [index, entry] of history.entries()) {
    const historyRole = resolveHistoryRole(entry, index);
    const text = sanitizePromptNarrativeText(
      entry.text,
      historyRole === 'action'
        ? '玩家做出了新的决定。'
        : '这一轮的局势已经出现了新的变化。',
    );
    if (!text) {
      continue;
    }

    if (historyRole === 'action') {
      if (currentRound && hasRoundContent(currentRound)) {
        rounds.push(currentRound);
      }

      currentRound = {
        actionText: text,
        resultTexts: [],
      };
      continue;
    }

    if (!currentRound) {
      currentRound = {
        actionText: null,
        resultTexts: [],
      };
    }

    currentRound.resultTexts.push(text);
  }

  if (currentRound && hasRoundContent(currentRound)) {
    rounds.push(currentRound);
  }

  return rounds;
}

function formatRoundOriginal(round: StoryHistoryRound) {
  const resultText = round.resultTexts.join('\n').trim() || '本轮没有明显的结果文本。';

  return [
    round.actionText
      ? `玩家行动：${round.actionText}`
      : '玩家行动：本轮没有明确的行动文本。',
    `剧情结果：${resultText}`,
  ].join('\n');
}

function summarizeRound(round: StoryHistoryRound) {
  const actionText = round.actionText ? normalizeWhitespace(round.actionText) : '';
  const resultText = normalizeWhitespace(round.resultTexts.join(' '));

  if (actionText && resultText) {
    return `玩家选择了“${truncateText(actionText, ACTION_SUMMARY_LIMIT)}”，随后${truncateText(resultText, RESULT_SUMMARY_LIMIT)}`;
  }

  if (resultText) {
    return truncateText(resultText, RESULT_SUMMARY_LIMIT);
  }

  if (actionText) {
    return `玩家选择了“${truncateText(actionText, ACTION_SUMMARY_LIMIT)}”。`;
  }

  return '这一轮没有留下可用的剧情文本。';
}

function _summarizeRoundGroup(rounds: StoryHistoryRound[]) {
  const firstRound = rounds[0];
  if (!firstRound) {
    return '没有可供总结的剧情记录。';
  }

  if (rounds.length === 1) {
    return summarizeRound(firstRound);
  }

  const secondRound = rounds[1];
  if (rounds.length === 2 && secondRound) {
    return `${summarizeRound(firstRound)} ${summarizeRound(secondRound)}`;
  }

  const lastRound = rounds[rounds.length - 1] ?? firstRound;
  return `${summarizeRound(firstRound)} 之后又推进了${rounds.length - 2}轮相关剧情。${summarizeRound(lastRound)}`;
}

function summarizeOlderRounds(rounds: StoryHistoryRound[]) {
  if (rounds.length === 0) {
    return null;
  }

  const groupSize = Math.max(1, Math.ceil(rounds.length / MAX_SUMMARY_GROUPS));
  const summaryLines: string[] = [];

  for (let index = 0; index < rounds.length; index += groupSize) {
    const group = rounds.slice(index, index + groupSize);
    summaryLines.push(`- ${group.map(summarizeRound).join(' ')}`);
  }

  return summaryLines.join('\n');
}

function summarizeOlderRoundsCompact(rounds: StoryHistoryRound[]) {
  return summarizeOlderRounds(rounds);
}

export function createHistoryMoment(
  text: string,
  historyRole: StoryHistoryRole,
  options: StoryOption[] = [],
): StoryMoment {
  return {
    text,
    options,
    historyRole,
  };
}

export function buildStoryPromptHistory(history: StoryMoment[]): StoryPromptHistory {
  const rounds = buildStoryRounds(history);
  if (rounds.length === 0) {
    return {
      recentOriginalRounds: [],
      previousSummary: null,
    };
  }

  const recentRounds = rounds.slice(-RECENT_ROUND_COUNT);
  const previousRounds = rounds.slice(0, -RECENT_ROUND_COUNT);

  return {
    recentOriginalRounds: recentRounds.map(formatRoundOriginal),
    previousSummary: summarizeOlderRoundsCompact(previousRounds),
  };
}