import type { UserSelection, SlidePlan, Zone, InternalRegion, LayoutPresetId } from "../types/designAgent";

/**
 * Phase Z 초기 선택 상태 생성
 * SlidePlan의 결과를 초기 값으로 사용 (Step 11까지의 결과 반영)
 */
export function createInitialUserSelection(slidePlan?: SlidePlan | null): UserSelection {
  const initialSections: Record<string, string[]> = {};
  const initialFrames: Record<string, string> = {};

  if (slidePlan) {
    slidePlan.zones.forEach(zone => {
      // 1. 모든 섹션을 각자의 지정된 존에 할당 (초안 배치)
      initialSections[zone.zone_id] = [...zone.section_ids];

      // 2. 각 리전의 기본 frame.
      // 2026-05-14 — backend frame_match_strategy.frame_id 가 있을 때만 init.
      //   null 인 경우 (backend current_default_candidate=None 등) frame_candidates[0]
      //   로 자동 채우지 않음 → SlideCanvas 의 preview overlay 트리거 조건
      //   (override !== default) 안 발동. 사용자가 직접 frame 클릭해야 preview 보임.
      //   배경 : 04-1 같은 case 에서 backend selection_path=rank_1 (env toggle 통과)
      //   이어도 current_default=None 이면 default 와 override mismatch 로 preview 강제 발동.
      zone.internal_regions.forEach(region => {
        const topFrameId = region.frame_match_strategy.frame_id;
        if (topFrameId) {
          initialFrames[region.id] = topFrameId;
        }
      });
    });
  }

  return {
    selectedSectionId: null,
    selectedZoneId: slidePlan?.zones[0]?.id || null,
    selectedRegionId: slidePlan?.zones[0]?.internal_regions[0]?.id || null,
    overrides: {
      layout_preset: slidePlan?.layout_preset,
      zone_frames: initialFrames,
      zone_sections: initialSections,
      zone_sizes: {},
      zone_geometries: {},
    },
  };
}

export function saveZoneGeometry(
  selection: UserSelection, 
  zoneId: string, 
  geometry: { x: number; y: number; w: number; h: number }
): UserSelection {
  return {
    ...selection,
    overrides: {
      ...selection.overrides,
      zone_geometries: {
        ...selection.overrides.zone_geometries,
        [zoneId]: geometry,
      }
    }
  };
}

export function saveZoneSizes(selection: UserSelection, groupId: string, sizes: number[]): UserSelection {
  return {
    ...selection,
    overrides: {
      ...selection.overrides,
      zone_sizes: {
        ...selection.overrides.zone_sizes,
        [groupId]: sizes,
      }
    }
  };
}

/**
 * 특정 섹션을 새로운 존으로 이동 (Drag & Drop)
 */
export function moveSectionToZone(
  selection: UserSelection, 
  sectionId: string, 
  targetZoneId: string
): UserSelection {
  const newZoneSections = { ...selection.overrides.zone_sections };
  
  // 1. 모든 존에서 해당 섹션 제거 (이동 전 위치 클리어)
  Object.keys(newZoneSections).forEach(zid => {
    newZoneSections[zid] = newZoneSections[zid].filter(id => id !== sectionId);
  });

  // 2. 타겟 존에 섹션 추가
  if (!newZoneSections[targetZoneId]) {
    newZoneSections[targetZoneId] = [];
  }
  if (!newZoneSections[targetZoneId].includes(sectionId)) {
    newZoneSections[targetZoneId].push(sectionId);
  }

  return {
    ...selection,
    overrides: {
      ...selection.overrides,
      zone_sections: newZoneSections
    }
  };
}

export function selectZone(selection: UserSelection, zoneId: string | null): UserSelection {
  return {
    ...selection,
    selectedZoneId: zoneId,
    selectedRegionId: null, // Zone이 바뀌면 Region 선택 해제
  };
}

export function selectRegion(selection: UserSelection, regionId: string | null): UserSelection {
  return {
    ...selection,
    selectedRegionId: regionId,
  };
}

export function applyLayout(selection: UserSelection, layoutId: LayoutPresetId): UserSelection {
  return {
    ...selection,
    overrides: {
      ...selection.overrides,
      layout_preset: layoutId,
    },
  };
}

export function applyFrame(selection: UserSelection, regionId: string, frameId: string): UserSelection {
  return {
    ...selection,
    overrides: {
      ...selection.overrides,
      zone_frames: {
        ...selection.overrides.zone_frames,
        [regionId]: frameId,
      },
    },
  };
}

/**
 * 현재 선택된 Zone 객체 반환
 */
export function getSelectedZone(slidePlan: SlidePlan | null, selection: UserSelection): Zone | null {
  if (!slidePlan || !selection.selectedZoneId) return null;
  // id 또는 zone_id 매칭
  return slidePlan.zones.find(z => z.id === selection.selectedZoneId || z.zone_id === selection.selectedZoneId) || null;
}

/**
 * 현재 선택된 Region 객체 반환
 */
export function getSelectedRegion(zone: Zone | null, selection: UserSelection): InternalRegion | null {
  if (!zone || !selection.selectedRegionId) return null;
  return zone.internal_regions.find(r => r.id === selection.selectedRegionId) || null;
}

/**
 * 특정 Zone에 할당된 섹션 ID 목록 반환 (오버라이드 우선)
 */
export function getSectionsForZone(zone: Zone, selection: UserSelection): string[] {
  return selection.overrides.zone_sections[zone.zone_id] || zone.section_ids;
}

/**
 * 최종 유효 레이아웃 ID 반환
 */
export function getEffectiveLayoutId(slidePlan: SlidePlan | null, selection: UserSelection): LayoutPresetId {
  if (selection.overrides.layout_preset) return selection.overrides.layout_preset;
  return slidePlan?.layout_preset || 'single';
}