import type {
  ChapterState,
  GameState,
  StorySignal,
  WorldMutation,
} from '../../types';

function dedupeStrings(values: Array<string | null | undefined>, limit = 6) {
  return [...new Set(values.map((value) => value?.trim() ?? '').filter(Boolean))]
    .slice(0, limit);
}

export function resolveWorldMutations(params: {
  state: GameState;
  signals: StorySignal[];
  chapterState: ChapterState | null | undefined;
}) {
  const currentSceneId = params.state.currentScenePreset?.id;
  const activeThreadIds = params.state.storyEngineMemory?.activeThreadIds ?? [];
  const mutations: WorldMutation[] = [];

  if (currentSceneId && params.chapterState) {
    mutations.push({
      id: `mutation:scene:${currentSceneId}:${params.chapterState.stage}`,
      mutationType: 'scene_text',
      targetId: currentSceneId,
      reason: `${params.chapterState.title}正在改写这片地界的表面气氛。`,
      relatedThreadIds: params.chapterState.primaryThreadIds,
    });
  }

  if (currentSceneId && params.signals.some((signal) => signal.signalType === 'win_battle')) {
    mutations.push({
      id: `mutation:pressure:${currentSceneId}:battle`,
      mutationType: 'enemy_pressure',
      targetId: currentSceneId,
      reason: '这一带的敌意正在因交锋结果重新聚拢。',
      relatedThreadIds: dedupeStrings(activeThreadIds, 4),
    });
  }

  if (params.signals.some((signal) => signal.signalType === 'obtain_carrier')) {
    mutations.push({
      id: `mutation:attitude:${currentSceneId ?? 'scene'}:carrier`,
      mutationType: 'npc_attitude',
      targetId: currentSceneId ?? 'scene',
      reason: '关键载体已经落到你手里，相关角色的口风会开始变化。',
      relatedThreadIds: dedupeStrings(activeThreadIds, 4),
    });
  }

  if (params.chapterState?.stage === 'climax' && currentSceneId) {
    mutations.push({
      id: `mutation:route:${currentSceneId}:climax`,
      mutationType: 'route_unlock',
      targetId: currentSceneId,
      reason: '章节高潮逼近，新的通路或对峙点开始显影。',
      relatedThreadIds: params.chapterState.primaryThreadIds,
    });
  }

  return mutations;
}

export function applyWorldMutationsToGameState(params: {
  state: GameState;
  mutations: WorldMutation[];
}) {
  const knownMutations = [
    ...(params.state.storyEngineMemory?.worldMutations ?? []),
    ...params.mutations,
  ];
  if (knownMutations.length <= 0) {
    return params.state;
  }

  const currentSceneId = params.state.currentScenePreset?.id ?? null;
  const relevantMutations = currentSceneId
    ? knownMutations.filter((mutation) => mutation.targetId === currentSceneId)
    : knownMutations;
  const latestSceneMutation = relevantMutations
    .filter((mutation) => mutation.mutationType === 'scene_text')
    .at(-1);
  const pressureMutationCount = relevantMutations.filter(
    (mutation) => mutation.mutationType === 'enemy_pressure',
  ).length;
  const attitudeMutation = relevantMutations
    .filter((mutation) => mutation.mutationType === 'npc_attitude')
    .at(-1);
  const currentPressureLevel =
    pressureMutationCount >= 3
      ? 'extreme'
      : pressureMutationCount === 2
        ? 'high'
        : pressureMutationCount === 1
          ? 'medium'
          : params.state.currentScenePreset?.currentPressureLevel ?? 'low';

  return {
    ...params.state,
    currentScenePreset: params.state.currentScenePreset
      ? {
          ...params.state.currentScenePreset,
          mutationStateText:
            [latestSceneMutation?.reason, attitudeMutation?.reason]
              .filter(Boolean)
              .join(' ')
            ?? params.state.currentScenePreset.mutationStateText
            ?? null,
          currentPressureLevel,
          description: [
            params.state.currentScenePreset.description,
            latestSceneMutation?.reason,
          ]
            .filter(Boolean)
            .join(' '),
          npcs: params.state.currentScenePreset.npcs?.map((npc) => ({
            ...npc,
            description:
              attitudeMutation && !npc.hostile
                ? `${npc.description} ${attitudeMutation.reason}`
                : npc.description,
          })),
        }
      : params.state.currentScenePreset,
  };
}