import {
  buildNpcGiftModalState,
  buildNpcRecruitModalState,
  buildNpcTradeModalState,
  NPC_GIFT_FUNCTION,
  NPC_RECRUIT_FUNCTION,
  NPC_TRADE_FUNCTION,
  shouldNpcRecruitOpenModal,
} from '../../data/functionCatalog';
import {
  applyQuestProgressFromSceneReached,
} from '../../data/questFlow';
import { MAX_COMPANIONS } from '../../data/npcInteractions';
import { incrementGameRuntimeStats } from '../../data/runtimeStats';
import { ensureSceneEncounterPreview } from '../../data/sceneEncounterPreviews';
import { getScenePresetById } from '../../data/scenePresets';
import {
  AnimationState,
  type Encounter,
  type GameState,
  type StoryOption,
} from '../../types';
import type {
  GiftModalState,
  RecruitModalState,
  TradeModalState,
} from './uiTypes';

export type NpcInteractionDecision =
  | { kind: 'none' }
  | { kind: 'trade_modal'; modal: TradeModalState }
  | { kind: 'gift_modal'; modal: GiftModalState }
  | { kind: 'recruit_modal'; modal: RecruitModalState }
  | { kind: 'recruit_immediate' };

export type MapTravelResolution = {
  nextState: GameState;
  actionText: string;
  travelResultText: string;
};

function isNpcEncounter(
  encounter: GameState['currentEncounter'],
): encounter is Encounter {
  return Boolean(encounter?.kind === 'npc');
}

export function getNpcEncounterKey(encounter: Encounter) {
  return encounter.id ?? encounter.npcName;
}

function findPreferredTradeItemId(
  items: Array<{ itemId: string; canSubmit: boolean }>,
) {
  return items.find(item => item.canSubmit)?.itemId ?? items[0]?.itemId ?? null;
}

export function resolveNpcInteractionDecision(
  state: GameState,
  option: StoryOption,
): NpcInteractionDecision {
  if (
    !state.playerCharacter ||
    !option.interaction ||
    !isNpcEncounter(state.currentEncounter)
  ) {
    return { kind: 'none' };
  }

  const encounter = state.currentEncounter;

  switch (option.functionId) {
    case NPC_TRADE_FUNCTION.id:
      return {
        kind: 'trade_modal',
        modal: buildNpcTradeModalState(
          encounter,
          option.actionText,
          findPreferredTradeItemId(
            state.runtimeNpcInteraction?.trade.buyItems ?? [],
          ),
          findPreferredTradeItemId(
            state.runtimeNpcInteraction?.trade.sellItems ?? [],
          ),
        ),
      };
    case NPC_GIFT_FUNCTION.id:
      {
        const selectedGiftItemId =
          state.runtimeNpcInteraction?.gift.items.find(item => item.canSubmit)
            ?.itemId ??
          state.runtimeNpcInteraction?.gift.items[0]?.itemId ??
          null;
        if (!selectedGiftItemId) {
          return { kind: 'none' };
        }

        return {
          kind: 'gift_modal',
          modal: buildNpcGiftModalState(
            encounter,
            option.actionText,
            selectedGiftItemId,
          ),
        };
      }
    case NPC_RECRUIT_FUNCTION.id:
      if (shouldNpcRecruitOpenModal(state.companions.length, MAX_COMPANIONS)) {
        return {
          kind: 'recruit_modal',
          modal: buildNpcRecruitModalState(state, encounter, option.actionText),
        };
      }

      return { kind: 'recruit_immediate' };
    default:
      return { kind: 'none' };
  }
}

export function buildMapTravelResolution(
  state: GameState,
  sceneId: string,
): MapTravelResolution | null {
  if (!state.worldType || !state.playerCharacter) {
    return null;
  }

  const targetScene = getScenePresetById(state.worldType, sceneId);
  if (!targetScene || targetScene.id === state.currentScenePreset?.id) {
    return null;
  }

  const nextState = ensureSceneEncounterPreview({
    ...state,
    runtimeStats: incrementGameRuntimeStats(state.runtimeStats, {
      scenesTraveled: 1,
    }),
    quests: applyQuestProgressFromSceneReached(state.quests, targetScene.id),
    currentScenePreset: targetScene,
    currentEncounter: null,
    npcInteractionActive: false,
    sceneHostileNpcs: [],
    playerX: 0,
    playerFacing: 'right' as const,
    animationState: AnimationState.IDLE,
    playerActionMode: 'idle' as const,
    activeCombatEffects: [],
    scrollWorld: false,
    inBattle: false,
    lastObserveSignsSceneId: null,
    lastObserveSignsReport: null,
    currentBattleNpcId: null,
    currentNpcBattleMode: null,
    currentNpcBattleOutcome: null,
    sparReturnEncounter: null,
    sparPlayerHpBefore: null,
    sparPlayerMaxHpBefore: null,
    sparStoryHistoryBefore: null,
  });
  const travelResultText = `你离开${state.currentScenePreset?.name ?? '当前位置'}，前往${targetScene.name}。`;

  return {
    nextState,
    actionText: `前往${targetScene.name}`,
    travelResultText,
  };
}