package foundation.data.entity;

import java.sql.PreparedStatement;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import foundation.data.meta.field.Field;
import foundation.data.meta.field.FieldsRuntime;
import foundation.json.IJSONProvider;
import foundation.json.IJSONWriter;
import foundation.persist.ISavable;


public class EntitySet implements Iterable<Entity>, IJSONProvider, ISavable {

	protected String dataName;
	protected FieldsRuntime fieldMetas;
	protected List<Entity> entityList;
	protected int maxSize;
	protected Indexes indexes;

	
	public EntitySet(FieldsRuntime fieldMetas) {
		this(fieldMetas, -1);
	}

	public EntitySet(FieldsRuntime fieldMetas, int maxSize) {
		this.fieldMetas = fieldMetas;
		
		if (maxSize > 0) {
			this.maxSize = maxSize;
			entityList = new ArrayList<Entity>(maxSize);
		}
		else {
			entityList = new ArrayList<Entity>(15);
		}
		
		indexes = new Indexes(this);
	}


	public static EntitySet appendAll(EntitySet target, EntitySet source) {
		if (target == null || source == null) {
			return source;
		}
		
		for (Entity entity : source) {
			target.append(entity);
		}
		
		return target;
	}
	
	public EntitySetChange getChange(EntitySet original) throws Exception {
		EntitySetChange result = new EntitySetChange();
		
		//1. 如果 original 为空，返回当前 entitySet 所有数据
		if (original == null) {
			for (Entity entity: this) {
				Entity item = new Entity(fieldMetas);
				item.copyFrom(entity);
				
				EntityChange entityChange = new EntityChange(item, ChangeType.Inserted);
				result.loadOne(entityChange);
			}
			
			return result;
		}
		
		//2. 如果 original 不为空，对比 entity
		for (Entity entity: this) {
			String id = entity.getId();
			Entity originalEntity = original.getEntity("id", id);
			EntityChange entityChange = entity.getChange(originalEntity);
			
			result.loadOne(entityChange);
		}
		
		//3. 如果 original存在，this不存在，就是Delete
		for (Entity originalEntity: original) {
			String id = originalEntity.getId();
			Entity entity = getEntity("id", id);
			
			if (entity != null) {
				continue;
			}
			
			Entity item = new Entity(fieldMetas);
			item.copyFrom(originalEntity);
			
			EntityChange entityChange = new EntityChange(item, ChangeType.Deleted);
			result.loadOne(entityChange);
		}
		
		return result;
	}
	
	public Entity newEntity() {
		Entity entity = new Entity(fieldMetas);
		return entity;
	}
	
	public Entity append() {
		Entity entity = new Entity(fieldMetas);
		entityList.add(entity);

		return entity;
	}
	
	public Entity append(Entity entity) {
		entityList.add(entity);
		indexes.setDirty();
		
		return entity;
	}

	public Entity getEntity(int idx) {
		Entity entity = entityList.get(idx);
		
		if (entity == null || entity.isDeleted()) {
			return null;
		}
		
		return entity;
	}
	
	public Entity getEntity(String id) throws Exception {
		if (id == null) {
			return null;
		}
		
		Entity entity = indexes.getEntity("id", id);
		
		if (entity == null || entity.isDeleted()) {
			return null;
		}
		
		return entity;
	}
	
	public Entity getEntity(String field, Object value) throws Exception {
		Entity entity =  indexes.getEntity(field, value);
		
		if (entity == null || entity.isDeleted()) {
			return null;
		}
		
		return entity;
	}
	 
	public boolean lookup(String field, Object value) throws Exception {
		Entity entity =  indexes.getEntity(field, value);
		return entity != null;
	}

	public boolean contains(String field, Object value) throws Exception {
		return indexes.contains(field, value);
	}

	public Object getMax(String fieldName) {
		return indexes.getMax(fieldName);
	}
	
	public void delete(String id) throws Exception {
		if (id == null) {
			return;
		}
		
		Entity entity = indexes.getEntity("id", id);
		
		if (entity == null) {
			return;
		}
		
		entity.setDeleted();
	}

	@Override
	public void saveData(PreparedStatement stmt, Object... agrs) throws Exception {
		int max = fieldMetas.size(); 
		Object value; Field field;
		
		for (Entity entity: this) {
			for (int i = 0; i < max; i++) {
				value = entity.getFieldTypeValue(i);
				
				if (value == null) {
					field = fieldMetas.get(i);
					stmt.setNull(i + 1, field.getSQLType());
					continue;
				}
				
				stmt.setObject(i + 1, value);
			}
			
			stmt.addBatch();
		}
		
		stmt.executeBatch(); 
	}
	
	public void clear() {
		entityList.clear();
	}

	public boolean isEmpty() {
		return entityList.isEmpty();
	}
	
	public boolean isFull() {
		if (maxSize < 0) {
			return false;
		}
		
		return entityList.size() >= maxSize;
	}
	
	public int getFieldCount() {
		return fieldMetas.getFieldCount();
	}

	public FieldsRuntime getEntityMeta() {
		return fieldMetas;
	}

	public List<Entity> getEntityList() {
		return entityList;
	}

	@Override
	public Iterator<Entity> iterator() {
		return entityList.iterator();
	}

	public int size() {
		return entityList.size();
	}

	public String[] getLowerNames() {
		return fieldMetas.getLowerNames();
	}
	
	@Override
	public void writeJSON(IJSONWriter writer) {
		writer.beginArray();
		writeJSONBody(writer);
		writer.endArray();		
	}

	public void writeJSONBody(IJSONWriter writer) {
		for (Entity entity : this) {
			entity.writeJSON(writer);
		}
	}
}