import { Field, FieldVersion, FieldVersionChange } from '../types/field';

/**
 * 地块版本管理工具
 */

// 生成唯一ID
const generateId = () => {
  return `${Date.now()}-${Math.random().toString(36).substr(2, 9)}`;
};

// 比较两个值是否不同
const isDifferent = (oldValue: any, newValue: any): boolean => {
  if (Array.isArray(oldValue) && Array.isArray(newValue)) {
    return JSON.stringify(oldValue) !== JSON.stringify(newValue);
  }
  return oldValue !== newValue;
};

// 检测字段变更
const detectChanges = (oldField: Partial<Field>, newField: Partial<Field>): FieldVersionChange[] => {
  const changes: FieldVersionChange[] = [];
  
  // 需要监控的字段
  const monitoredFields = [
    'name',
    'code',
    'area',
    'perimeter',
    'location',
    'soilType',
    'landUseType',
    'plantingMode',
    'owner',
    'ownerPhone',
    'contractPeriod',
    'certificateNumber',
    'tags',
    'status',
    'elevation',
    'slope',
    'aspect',
    'waterSource',
    'remarks',
  ];

  for (const field of monitoredFields) {
    const oldValue = (oldField as any)[field];
    const newValue = (newField as any)[field];
    
    if (isDifferent(oldValue, newValue)) {
      changes.push({
        field,
        oldValue,
        newValue,
      });
    }
  }

  return changes;
};

// 检测边界变更
const isBoundaryChanged = (oldCoordinates: any[], newCoordinates: any[]): boolean => {
  if (!oldCoordinates || !newCoordinates) return false;
  if (oldCoordinates.length !== newCoordinates.length) return true;
  return JSON.stringify(oldCoordinates) !== JSON.stringify(newCoordinates);
};

/**
 * 创建版本记录
 */
export const createFieldVersion = (
  oldField: Field | null,
  newField: Field,
  changeType: FieldVersion['changeType'],
  changedBy: string,
  remarks?: string
): FieldVersion | null => {
  // 如果是新建，创建初始版本
  if (changeType === 'create') {
    return {
      id: generateId(),
      fieldId: newField.id,
      version: 1,
      changeType: 'create',
      changes: [],
      coordinates: newField.coordinates,
      attributes: { ...newField },
      changedBy,
      changedAt: new Date().toISOString(),
      remarks: remarks || '创建地块',
    };
  }

  // 如果没有旧数据，无法比较
  if (!oldField) return null;

  // 检测变更
  const attributeChanges = detectChanges(oldField, newField);
  const boundaryChanged = isBoundaryChanged(oldField.coordinates, newField.coordinates);

  // 如果有边界变更，添加到变更列表
  if (boundaryChanged) {
    attributeChanges.push({
      field: 'coordinates',
      oldValue: oldField.coordinates.length,
      newValue: newField.coordinates.length,
    });
  }

  // 如果没有任何变更，不创建版本
  if (attributeChanges.length === 0 && !boundaryChanged) {
    return null;
  }

  // 确定变更类型
  let finalChangeType = changeType;
  if (changeType === 'update-boundary' || changeType === 'update-attributes') {
    // 自动检测
    if (boundaryChanged && attributeChanges.length > 1) {
      finalChangeType = 'update-boundary'; // 边界变更优先
    } else if (boundaryChanged) {
      finalChangeType = 'update-boundary';
    } else {
      finalChangeType = 'update-attributes';
    }
  }

  return {
    id: generateId(),
    fieldId: newField.id,
    version: (oldField.currentVersion || 0) + 1,
    changeType: finalChangeType,
    changes: attributeChanges,
    coordinates: boundaryChanged ? newField.coordinates : undefined,
    attributes: { ...newField },
    changedBy,
    changedAt: new Date().toISOString(),
    remarks,
  };
};

/**
 * 保存版本到localStorage
 */
export const saveFieldVersion = (version: FieldVersion): void => {
  try {
    const key = `field_versions_${version.fieldId}`;
    const data = localStorage.getItem(key);
    let versions: FieldVersion[] = data ? JSON.parse(data) : [];
    
    // 添加新版本
    versions.push(version);
    
    // 保存
    localStorage.setItem(key, JSON.stringify(versions));
  } catch (error) {
    console.error('保存版本失败:', error);
    throw error;
  }
};

/**
 * 加载地块的所有版本
 */
export const loadFieldVersions = (fieldId: string): FieldVersion[] => {
  try {
    const key = `field_versions_${fieldId}`;
    const data = localStorage.getItem(key);
    return data ? JSON.parse(data) : [];
  } catch (error) {
    console.error('加载版本失败:', error);
    return [];
  }
};

/**
 * 获取特定版本
 */
export const getFieldVersion = (fieldId: string, version: number): FieldVersion | null => {
  const versions = loadFieldVersions(fieldId);
  return versions.find(v => v.version === version) || null;
};

/**
 * 从版本恢复地块数据
 */
export const restoreFromVersion = (version: FieldVersion): Partial<Field> => {
  if (!version.attributes) {
    throw new Error('版本数据不完整');
  }
  
  const restored: Partial<Field> = { ...version.attributes };
  
  // 如果有边界数据，使用版本的边界
  if (version.coordinates) {
    restored.coordinates = version.coordinates;
  }
  
  return restored;
};

/**
 * 删除地块的所有版本记录
 */
export const deleteFieldVersions = (fieldId: string): void => {
  try {
    const key = `field_versions_${fieldId}`;
    localStorage.removeItem(key);
  } catch (error) {
    console.error('删除版本失败:', error);
  }
};

/**
 * 获取版本统计信息
 */
export const getVersionStatistics = (fieldId: string) => {
  const versions = loadFieldVersions(fieldId);
  
  return {
    total: versions.length,
    byType: versions.reduce((acc, v) => {
      acc[v.changeType] = (acc[v.changeType] || 0) + 1;
      return acc;
    }, {} as Record<FieldVersion['changeType'], number>),
    latestVersion: versions.length > 0 
      ? Math.max(...versions.map(v => v.version))
      : 0,
  };
};