import { 
  PopGridPosition, 
  GridMode, 
  GRID_BREAKPOINTS 
} from "../types/pop-layout";

// ========================================
// 그리드 위치 변환
// ========================================

/**
 * 12칸 기준 위치를 다른 모드로 변환
 */
export function convertPositionToMode(
  position: PopGridPosition,
  targetMode: GridMode
): PopGridPosition {
  const sourceColumns = 12;
  const targetColumns = GRID_BREAKPOINTS[targetMode].columns;
  
  // 같은 칸 수면 그대로 반환
  if (sourceColumns === targetColumns) {
    return position;
  }
  
  const ratio = targetColumns / sourceColumns;
  
  // 열 위치 변환
  let newCol = Math.max(1, Math.ceil((position.col - 1) * ratio) + 1);
  let newColSpan = Math.max(1, Math.round(position.colSpan * ratio));
  
  // 범위 초과 방지
  if (newCol > targetColumns) {
    newCol = 1;
  }
  if (newCol + newColSpan - 1 > targetColumns) {
    newColSpan = targetColumns - newCol + 1;
  }
  
  return {
    col: newCol,
    row: position.row,
    colSpan: Math.max(1, newColSpan),
    rowSpan: position.rowSpan,
  };
}

// ========================================
// 겹침 감지 및 해결
// ========================================

/**
 * 두 위치가 겹치는지 확인
 */
export function isOverlapping(a: PopGridPosition, b: PopGridPosition): boolean {
  // 열 겹침 체크
  const aColEnd = a.col + a.colSpan - 1;
  const bColEnd = b.col + b.colSpan - 1;
  const colOverlap = !(aColEnd < b.col || bColEnd < a.col);
  
  // 행 겹침 체크
  const aRowEnd = a.row + a.rowSpan - 1;
  const bRowEnd = b.row + b.rowSpan - 1;
  const rowOverlap = !(aRowEnd < b.row || bRowEnd < a.row);
  
  return colOverlap && rowOverlap;
}

/**
 * 겹침 해결 (아래로 밀기)
 */
export function resolveOverlaps(
  positions: Array<{ id: string; position: PopGridPosition }>,
  columns: number
): Array<{ id: string; position: PopGridPosition }> {
  // row, col 순으로 정렬
  const sorted = [...positions].sort((a, b) => 
    a.position.row - b.position.row || a.position.col - b.position.col
  );
  
  const resolved: Array<{ id: string; position: PopGridPosition }> = [];
  
  sorted.forEach((item) => {
    let { row, col, colSpan, rowSpan } = item.position;
    
    // 열이 범위를 초과하면 조정
    if (col + colSpan - 1 > columns) {
      colSpan = columns - col + 1;
    }
    
    // 기존 배치와 겹치면 아래로 이동
    let attempts = 0;
    const maxAttempts = 100;
    
    while (attempts < maxAttempts) {
      const currentPos: PopGridPosition = { col, row, colSpan, rowSpan };
      const hasOverlap = resolved.some(r => isOverlapping(currentPos, r.position));
      
      if (!hasOverlap) break;
      
      row++;
      attempts++;
    }
    
    resolved.push({
      id: item.id,
      position: { col, row, colSpan, rowSpan },
    });
  });
  
  return resolved;
}

// ========================================
// 좌표 변환
// ========================================

/**
 * 마우스 좌표 → 그리드 좌표 변환
 */
export function mouseToGridPosition(
  mouseX: number,
  mouseY: number,
  canvasRect: DOMRect,
  columns: number,
  rowHeight: number,
  gap: number,
  padding: number
): { col: number; row: number } {
  // 캔버스 내 상대 위치
  const relX = mouseX - canvasRect.left - padding;
  const relY = mouseY - canvasRect.top - padding;
  
  // 칸 너비 계산
  const totalGap = gap * (columns - 1);
  const colWidth = (canvasRect.width - padding * 2 - totalGap) / columns;
  
  // 그리드 좌표 계산 (1부터 시작)
  const col = Math.max(1, Math.min(columns, Math.floor(relX / (colWidth + gap)) + 1));
  const row = Math.max(1, Math.floor(relY / (rowHeight + gap)) + 1);
  
  return { col, row };
}

/**
 * 그리드 좌표 → 픽셀 좌표 변환
 */
export function gridToPixelPosition(
  col: number,
  row: number,
  colSpan: number,
  rowSpan: number,
  canvasWidth: number,
  columns: number,
  rowHeight: number,
  gap: number,
  padding: number
): { x: number; y: number; width: number; height: number } {
  const totalGap = gap * (columns - 1);
  const colWidth = (canvasWidth - padding * 2 - totalGap) / columns;
  
  return {
    x: padding + (col - 1) * (colWidth + gap),
    y: padding + (row - 1) * (rowHeight + gap),
    width: colWidth * colSpan + gap * (colSpan - 1),
    height: rowHeight * rowSpan + gap * (rowSpan - 1),
  };
}

// ========================================
// 위치 검증
// ========================================

/**
 * 위치가 그리드 범위 내에 있는지 확인
 */
export function isValidPosition(
  position: PopGridPosition,
  columns: number
): boolean {
  return (
    position.col >= 1 &&
    position.row >= 1 &&
    position.colSpan >= 1 &&
    position.rowSpan >= 1 &&
    position.col + position.colSpan - 1 <= columns
  );
}

/**
 * 위치를 그리드 범위 내로 조정
 */
export function clampPosition(
  position: PopGridPosition,
  columns: number
): PopGridPosition {
  let { col, row, colSpan, rowSpan } = position;
  
  // 최소값 보장
  col = Math.max(1, col);
  row = Math.max(1, row);
  colSpan = Math.max(1, colSpan);
  rowSpan = Math.max(1, rowSpan);
  
  // 열 범위 초과 방지
  if (col + colSpan - 1 > columns) {
    if (col > columns) {
      col = 1;
    }
    colSpan = columns - col + 1;
  }
  
  return { col, row, colSpan, rowSpan };
}

// ========================================
// 자동 배치
// ========================================

/**
 * 다음 빈 위치 찾기
 */
export function findNextEmptyPosition(
  existingPositions: PopGridPosition[],
  colSpan: number,
  rowSpan: number,
  columns: number
): PopGridPosition {
  let row = 1;
  let col = 1;
  
  const maxAttempts = 1000;
  let attempts = 0;
  
  while (attempts < maxAttempts) {
    const candidatePos: PopGridPosition = { col, row, colSpan, rowSpan };
    
    // 범위 체크
    if (col + colSpan - 1 > columns) {
      col = 1;
      row++;
      continue;
    }
    
    // 겹침 체크
    const hasOverlap = existingPositions.some(pos => 
      isOverlapping(candidatePos, pos)
    );
    
    if (!hasOverlap) {
      return candidatePos;
    }
    
    // 다음 위치로 이동
    col++;
    if (col + colSpan - 1 > columns) {
      col = 1;
      row++;
    }
    
    attempts++;
  }
  
  // 실패 시 마지막 행에 배치
  return { col: 1, row: row + 1, colSpan, rowSpan };
}

/**
 * 컴포넌트들을 자동으로 배치
 */
export function autoLayoutComponents(
  components: Array<{ id: string; colSpan: number; rowSpan: number }>,
  columns: number
): Array<{ id: string; position: PopGridPosition }> {
  const result: Array<{ id: string; position: PopGridPosition }> = [];
  
  let currentRow = 1;
  let currentCol = 1;
  
  components.forEach(comp => {
    // 현재 행에 공간이 부족하면 다음 행으로
    if (currentCol + comp.colSpan - 1 > columns) {
      currentRow++;
      currentCol = 1;
    }
    
    result.push({
      id: comp.id,
      position: {
        col: currentCol,
        row: currentRow,
        colSpan: comp.colSpan,
        rowSpan: comp.rowSpan,
      },
    });
    
    currentCol += comp.colSpan;
  });
  
  return result;
}