vql/vql.go

package vql

import (
	"encoding/json"
	"fmt"
	"strings"
	"sync"
)

type VirtualQlConvert func(val map[string]interface{}) (string, error)

func NoParameConvertFunc(vTable string, convertSql string) *VirtualTable {
	return &VirtualTable{
		MappingTableName: vTable,
		SqlConvert: func(val map[string]interface{}) (string, error) {
			return convertSql, nil
		},
	}
}

type VirtualTable struct {
	MappingTableName string   //example: user(db:db1,id:1)
	ArgNames         []string //example: [db,id]
	SqlConvert       VirtualQlConvert
}

func parseTableName(tableNameExpression string) (tableName string, args map[string]string, err error) {
	args = make(map[string]string)
	source := []rune(tableNameExpression)

	flag := "table"
	argStr := ""
	for i := range source {
		switch flag {
		case "table":
			if source[i] == '(' {
				flag = "arg"
				continue
			}
			tableName += string(source[i])
		case "arg":
			if source[i] == ')' {
				flag = "end"
				continue
			}
			argStr += string(source[i])
		case "end":
			break
		}
	}

	argsArr := []string{}
	if argStr != "" {
		argsArr = strings.Split(strings.TrimSpace(argStr), ",")
	}
	for i := range argsArr {
		arg := strings.Split(argsArr[i], ":")
		if len(arg) != 2 {
			err = fmt.Errorf("table name expression error")
			return
		}
		args[arg[0]] = arg[1]
	}

	return
}

var DefaultVirtualQL = &VirtualQL{}

type VirtualQL struct {
	tables map[string]VirtualTable
	locker sync.RWMutex
}

func (vql *VirtualQL) getTable(tableName string) (vt VirtualTable, args map[string]string, err error) {
	vql.locker.RLock()
	defer vql.locker.RUnlock()

	tableName, args, err = parseTableName(tableName)
	vqlTable := vql.tables[tableName]
	return vqlTable, args, err
}

func (vql *VirtualQL) Register(v *VirtualTable) {
	if vql.tables == nil {
		vql.tables = make(map[string]VirtualTable)
	}
	vql.locker.Lock()
	defer vql.locker.Unlock()
	vql.tables[v.MappingTableName] = *v
}

func (vql *VirtualQL) Compile(sql string, param map[string]interface{}) (*Query, error) {
	query, err := Analyze(sql)
	if err != nil {
		return nil, err
	}
	err = vql.convert(query, param)
	if err != nil {
		return nil, err
	}
	return query, nil
}

func (vql *VirtualQL) convert(query *Query, val map[string]interface{}) error {
	if query.From.Table == "" && query.From.SubQuery == nil {
		return fmt.Errorf("from table is empty")
	}
	if query.From.Table != "" {

		vtable, args, err := vql.getTable(query.From.Table)
		if err != nil {
			return err
		}
		if vtable.SqlConvert == nil {
			return fmt.Errorf("table %s is not register", query.From.Table)
		}

		if val == nil {
			val = make(map[string]interface{})
		}

		for k := range vtable.ArgNames {
			if args[vtable.ArgNames[k]] != "" {
				val[vtable.ArgNames[k]] = args[vtable.ArgNames[k]]
			}
		}

		convertSql, err := vtable.SqlConvert(val)
		if err != nil {
			return err
		}
		if convertSql == "" {
			return fmt.Errorf("table %s is not register!", query.From.Table)
		}

		newAs := query.From.As
		if newAs == "" {
			newAs = query.From.Table
		}
		query.From = From{
			raw: convertSql,
			As:  newAs,
		}
	} else {
		err := vql.convert(query.From.SubQuery, val)
		if err != nil {
			return err
		}
	}

	for i := range query.Join {
		err := vql.convert(query.Join[i].Query, val)
		if err != nil {
			return err
		}
	}

	return nil
}

func jsonEncode(val interface{}) string {
	raw, _ := json.Marshal(val)
	return string(raw)
}

func Analyze(sql string) (*Query, error) {
	q := Query{}
	err := q.FromSql(sql)
	return &q, err
}

// func (vql *VirtualQL) CompileWithApijson(sql apijson.QueryNode, param map[string]interface{}) (*Query, error) {

// }