package foundation.dao;

import java.util.HashSet;
import java.util.Set;

import foundation.json.IJSONProvider;
import foundation.json.IJSONWriter;
import foundation.persist.NamedSQL;
import foundation.server.config.Configer;
import foundation.server.config.DBaseType;
import foundation.variant.provider.DataEvent;
import foundation.variant.provider.IVariantsProvider;
import foundation.variant.provider.VariantProviderType;

public class Page implements IVariantsProvider, IJSONProvider {  
	
	public static String ProviderName = "page";
	public static Set<String> VariantNames;
	public static int Default_Page_Size;
	private DBaseType dbaseType;
    private int pageSize;  
    private int recordCount;  
    private int pageNo;
    private boolean empty;
  
    static {
    	VariantNames = new HashSet<String>();
    	VariantNames.add("pagesize");
    	VariantNames.add("recordcount");
    	VariantNames.add("pageno");
    	VariantNames.add("beginno");   
    	VariantNames.add(NamedSQL.Param_Page_limit);
    	VariantNames.add(NamedSQL.Param_Page_RowNo);
    	
    	Default_Page_Size = Configer.getInt("PageDefaultSize", 20);
    }
    
    public Page() {
    	this(null);
    } 
    
    public Page(DBaseType dbaseType) { 
    	if (dbaseType == null) {
    		dbaseType = DBaseType.getMain();
    	}
    	
    	this.pageSize = Default_Page_Size;
    	this.pageNo = 1;
    	this.recordCount = -1;
    	this.empty = false;
    	this.dbaseType = dbaseType;
    }

	public int getBeginRecordNo() { 
    	int recordNo = pageSize * (pageNo - 1) + 1; 
    	
    	//?
    	if (recordCount >= 0) {
    		recordNo = Math.min(recordCount, recordNo);
    	}
    	
        return recordNo;  
    }  
    
    public int getBeginRecordNo_1() { 
    	int recordNo = getBeginRecordNo();
        return Math.max(recordNo - 1, 0);  
    } 
    
    public int getEndRecordNo() {  
    	int recordNo = pageSize * pageNo;
    	
    	if (recordCount < 0) {
    		return recordNo;
    	}
    	
        return Math.min(recordNo, recordCount);  
    }  
    
    public int getPageSize() {  
        return pageSize;  
    }  
  
    public int getPageNo() {  
        return pageNo;
    }  
  
    public int getRecordCount() {  
        return recordCount;  
    }  
  
    public int getPageCount() {  
        return (int)Math.ceil(recordCount * 1.0d / pageSize);
    }  
  
    public void setRecordCount(int count) {
    	this.recordCount = count;
    }
  
    public void setPageSize(Integer value) { 
    	if (value == null) {
    		return;
    	}
    	
    	if (value <= 0) {
    		return;
    	}
    	
       	pageSize = value;  
    }  
    
	public void setPageNo(Integer value) {
    	if (value == null) {
    		return;
    	}
    	
    	if (value <= 0) {
    		return;
    	}
    	
		this.pageNo = value;
	}

	public void set(String name, String value) {
		name = name.toLowerCase();
		
		if ("pageno".equals(name)) {
			setPageNo(Integer.parseInt(value));
		}
		else if ("pagesize".equals(name)) {
			setPageSize(Integer.parseInt(value));			
		}
	}

 	public String toString() {
		StringBuilder result = new StringBuilder();
		
		result.append("size=").append(pageSize).append(",");
		result.append("recordCount=").append(recordCount).append(",");
		result.append("pageNo=").append(pageNo);
		
		return result.toString();
	}

	public boolean next() {
		//1. 如果没有总条数，直接页数增加
		if (recordCount < 0) {
			pageNo++;
			return true;
		}
		
		//2. 如果有总条数，根据总条数计算页数增加
		int pageCount = getPageCount();
		
		if (pageNo < pageCount) {
			pageNo++;
			return true;
		}
		
		return false;
	}

	public void setEmpty(boolean empty) {
		this.empty = empty;
	}

	public boolean isEmpty() {
		return empty;
	}

	public String toSQLString() {
		//1. MYSQL
		if (dbaseType.isMySQL()) {
			return " limit " + getBeginRecordNo_1() + ", " + pageSize;
		}
		
		//2. SQLServer
		if (dbaseType.isSQLServer()) {
			return " offset " + getBeginRecordNo_1() + " rows fetch next " + pageSize + " rows only";
		}
		
//		//3. Oracle
//		if (dbaseType.isOracle()) {
//			return " and rownum between " + getBeginRecordNo() + " and " + getEndRecordNo();
//		}
		
		return "";
	}
	
	@Override
	public String getProviderName() {
		return ProviderName;
	}

	@Override
	public VariantProviderType getProviderType() {
		return VariantProviderType.Transiant;
	}
	
	@Override
	public Set<String> getVariantNames() {
		return VariantNames;
	}

	@Override
	public boolean containsVariant(String name) {
		if (name == null) {
			return false;
		}
		
		name = name.toLowerCase();
		return VariantNames.contains(name);
	}

	@Override
	public Object getVariantValue(DataEvent dataEvent, String name) {
		if ("pageSize".equalsIgnoreCase(name)) {
			return pageSize;
		}
		else if ("recordCount".equalsIgnoreCase(name)) {
			return recordCount;
		}
		else if ("pageNo".equalsIgnoreCase(name)) {
			return pageNo;
		}
		else if ("beginNo".equalsIgnoreCase(name)) {
			int beginNo = getBeginRecordNo_1();
			return beginNo;
		}
		else if ("endNo".equalsIgnoreCase(name)) {
			int endNo = getEndRecordNo();
			return endNo;
		}
		else if (NamedSQL.Param_Page_limit.equalsIgnoreCase(name)) {
			return toSQLString();
		}
		else if (NamedSQL.Param_Page_RowNo.equalsIgnoreCase(name)) {
			return toSQLString();
		}
		
		return null;
	}

	
	@Override
	public void writeJSON(IJSONWriter writer) {
		writer.beginObject();
		writeJSONBody(writer);
		writer.endObject();		
	}

	public void writeJSONBody(IJSONWriter writer) {
		writer.write("recordcount", getRecordCount());
		writer.write("pagecount", getPageCount());
		writer.write("pagesize", getPageSize());
		writer.write("pageno", getPageNo());
	}

}