// Copyright Fuzamei Corp. 2018 All Rights Reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package table

import (
	"github.com/33cn/chain33/common/db"
	"github.com/33cn/chain33/types"
)

type tabler interface {
	getMeta() RowMeta
	getOpt() *Option
	indexPrefix(string) []byte
	GetData([]byte) (*Row, error)
	index(*Row, string) ([]byte, error)
	getIndexKey(string, []byte, []byte) []byte
	primaryPrefix() []byte
	getRow(value []byte) (*Row, error)
}

//Query 列表查询结构
type Query struct {
	table tabler
	kvdb  db.KVDB
}

//List 通过某个数据，查询
func (query *Query) List(indexName string, data types.Message, primaryKey []byte, count, direction int32) (rows []*Row, err error) {
	var prefix []byte
	if data != nil {
		query.table.getMeta().SetPayload(data)
		querykey := indexName
		if isPrimaryIndex(indexName) {
			querykey = query.table.getOpt().Primary
		}
		prefix, err = query.table.getMeta().Get(querykey)
		if err != nil {
			return nil, err
		}
	}
	return query.ListIndex(indexName, prefix, primaryKey, count, direction)
}

//ListOne 通过某个数据，查询一行
func (query *Query) ListOne(indexName string, data types.Message, primaryKey []byte) (row *Row, err error) {
	rows, err := query.List(indexName, data, primaryKey, 1, db.ListDESC)
	if err != nil {
		return nil, err
	}
	return rows[0], nil
}

func isPrimaryIndex(indexName string) bool {
	return indexName == "" || indexName == "auto" || indexName == "primary"
}

//ListIndex 根据索引查询列表
//index 用哪个index
//prefix 必须要符合的前缀, 可以为空
//primaryKey 开始查询的位置(不包含数据本身)
//count 最多取的数量
//direction 方向
func (query *Query) ListIndex(indexName string, prefix []byte, primaryKey []byte, count, direction int32) (rows []*Row, err error) {
	if isPrimaryIndex(indexName) || indexName == query.table.getOpt().Primary {
		return query.listPrimary(prefix, primaryKey, count, direction)
	}
	p := query.table.indexPrefix(indexName)
	var k []byte
	if len(primaryKey) > 0 {
		row, err := query.table.GetData(primaryKey)
		if err != nil {
			return nil, err
		}
		key, err := query.table.index(row, indexName)
		if err != nil {
			return nil, err
		}
		//如果存在prefix
		if prefix != nil {
			p2 := commonPrefix(prefix, key)
			if len(p2) != len(prefix) {
				return nil, types.ErrNotFound
			}
			p = append(p, p2...)
		}
		k = query.table.getIndexKey(indexName, key, row.Primary)
	} else {
		//这个情况下 k == nil
		p = append(p, prefix...)
	}
	values, err := query.kvdb.List(p, k, count, direction)
	if err != nil {
		return nil, err
	}
	for _, value := range values {
		row, err := query.table.GetData(value)
		if err != nil {
			return nil, err
		}
		rows = append(rows, row)
	}
	if len(rows) == 0 {
		return nil, types.ErrNotFound
	}
	return rows, nil
}

//ListPrimary list primary data
func (query *Query) listPrimary(prefix []byte, primaryKey []byte, count, direction int32) (rows []*Row, err error) {
	p := query.table.primaryPrefix()
	var k []byte
	if primaryKey != nil {
		if prefix != nil {
			p2 := commonPrefix(prefix, primaryKey)
			if len(p2) != len(prefix) {
				return nil, types.ErrNotFound
			}
			p = append(p, p2...)
		}
		k = append(p, primaryKey...)
	} else {
		p = append(p, prefix...)
	}
	values, err := query.kvdb.List(p, k, count, direction)
	if err != nil {
		return nil, err
	}
	for _, value := range values {
		row, err := query.table.getRow(value)
		if err != nil {
			return nil, err
		}
		rows = append(rows, row)
	}
	if len(rows) == 0 {
		return nil, types.ErrNotFound
	}
	return rows, nil
}

func commonPrefix(key1, key2 []byte) []byte {
	l1 := len(key1)
	l2 := len(key2)
	l := min(l1, l2)
	for i := 0; i < l; i++ {
		if key1[i] != key2[i] {
			return key1[:i]
		}
	}
	return key1[0:l]
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}