go-pkg/rsql/squirrel/sqlizer.go

package squirrel

import (
	"fmt"
	"strconv"
	"strings"

	"github.com/Masterminds/squirrel"
	"go.sour.is/pkg/rsql"
)

type dbInfo interface {
	Col(string) (string, error)
}

type args map[string]string

func (d *decoder) mkArgs(a args) args {
	m := make(args, len(a))
	for k, v := range a {
		if k == "limit" || k == "offset" {
			m[k] = v
			continue
		}

		var err error
		if k, err = d.dbInfo.Col(k); err == nil {
			m[k] = v

		}
	}

	return m
}

func (a args) Limit() (uint64, bool) {
	if a == nil {
		return 0, false
	}
	if v, ok := a["limit"]; ok {
		i, err := strconv.ParseUint(v, 10, 64)
		return i, err == nil
	}

	return 0, false
}
func (a args) Offset() (uint64, bool) {
	if a == nil {
		return 0, false
	}
	if v, ok := a["offset"]; ok {
		i, err := strconv.ParseUint(v, 10, 64)
		return i, err == nil
	}

	return 0, false
}
func (a args) Order() []string {
	var lis []string

	for k, v := range a {
		if k == "limit" || k == "offset" {
			continue
		}
		lis = append(lis, k+" "+v)
	}

	return lis
}

func Query(in string, db dbInfo) (squirrel.Sqlizer, args, error) {
	d := decoder{dbInfo: db}
	program := rsql.DefaultParse(in)
	sql, err := d.decode(program)
	return sql, d.mkArgs(program.Args), err
}

type decoder struct {
	dbInfo dbInfo
}

func (db *decoder) decode(in *rsql.Program) (squirrel.Sqlizer, error) {
	switch len(in.Statements) {
	case 0:
		return nil, nil
	case 1:
		return db.decodeStatement(in.Statements[0])
	default:
		a := squirrel.And{}
		for _, stmt := range in.Statements {
			d, err := db.decodeStatement(stmt)
			if d == nil {
				return nil, err
			}

			a = append(a, d)
		}
		return a, nil
	}
}
func (db *decoder) decodeStatement(in rsql.Statement) (squirrel.Sqlizer, error) {
	switch s := in.(type) {
	case *rsql.ExpressionStatement:
		return db.decodeExpression(s.Expression)
	}
	return nil, nil
}
func (db *decoder) decodeExpression(in rsql.Expression) (squirrel.Sqlizer, error) {
	switch e := in.(type) {
	case *rsql.InfixExpression:
		return db.decodeInfix(e)
	}
	return nil, nil
}
func (db *decoder) decodeInfix(in *rsql.InfixExpression) (squirrel.Sqlizer, error) {

	switch in.Token.Type {
	case rsql.TokAND:
		a := squirrel.And{}
		left, err := db.decodeExpression(in.Left)
		if err != nil {
			return nil, err
		}

		switch v := left.(type) {
		case squirrel.And:
			for _, el := range v {
				if el != nil {
					a = append(a, el)
				}
			}

		default:
			if v != nil {
				a = append(a, v)
			}
		}

		right, err := db.decodeExpression(in.Right)
		if err != nil {
			return nil, err
		}

		switch v := right.(type) {
		case squirrel.And:
			for _, el := range v {
				if el != nil {
					a = append(a, el)
				}
			}

		default:
			if v != nil {
				a = append(a, v)
			}
		}

		return a, nil
	case rsql.TokOR:
		left, err := db.decodeExpression(in.Left)
		if err != nil {
			return nil, err
		}
		right, err := db.decodeExpression(in.Right)
		if err != nil {
			return nil, err
		}

		return squirrel.Or{left, right}, nil
	case rsql.TokEQ:
		col, err := db.dbInfo.Col(in.Left.String())
		if err != nil {
			return nil, err
		}
		v, err := db.decodeValue(in.Right)
		if err != nil {
			return nil, err
		}

		return squirrel.Eq{col: v}, nil
	case rsql.TokLIKE:
		col, err := db.dbInfo.Col(in.Left.String())
		if err != nil {
			return nil, err
		}

		v, err := db.decodeValue(in.Right)
		if err != nil {
			return nil, err
		}

		switch value := v.(type) {
		case string:
			return Like{col, strings.Replace(value, "*", "%", -1)}, nil
		default:
			return nil, fmt.Errorf("LIKE requires a string value")
		}

	case rsql.TokNEQ:
		col, err := db.dbInfo.Col(in.Left.String())
		if err != nil {
			return nil, err
		}
		v, err := db.decodeValue(in.Right)
		if err != nil {
			return nil, err
		}

		return squirrel.NotEq{col: v}, nil
	case rsql.TokGT:
		col, err := db.dbInfo.Col(in.Left.String())
		if err != nil {
			return nil, err
		}
		v, err := db.decodeValue(in.Right)
		if err != nil {
			return nil, err
		}

		return squirrel.Gt{col: v}, nil
	case rsql.TokGE:
		col, err := db.dbInfo.Col(in.Left.String())
		if err != nil {
			return nil, err
		}
		v, err := db.decodeValue(in.Right)
		if err != nil {
			return nil, err
		}

		return squirrel.GtOrEq{col: v}, nil
	case rsql.TokLT:
		col, err := db.dbInfo.Col(in.Left.String())
		if err != nil {
			return nil, err
		}
		v, err := db.decodeValue(in.Right)
		if err != nil {
			return nil, err
		}

		return squirrel.Lt{col: v}, nil
	case rsql.TokLE:
		col, err := db.dbInfo.Col(in.Left.String())
		if err != nil {
			return nil, err
		}
		v, err := db.decodeValue(in.Right)
		if err != nil {
			return nil, err
		}

		return squirrel.LtOrEq{col: v}, nil
	default:
		return nil, nil
	}
}
func (db *decoder) decodeValue(in rsql.Expression) (interface{}, error) {
	switch v := in.(type) {
	case *rsql.Array:
		var values []interface{}
		for _, el := range v.Elements {
			v, err := db.decodeValue(el)
			if err != nil {
				return nil, err
			}

			values = append(values, v)
		}

		return values, nil
	case *rsql.InfixExpression:
		return db.decodeInfix(v)
	case *rsql.Identifier:
		return v.Value, nil
	case *rsql.Integer:
		return v.Value, nil
	case *rsql.Float:
		return v.Value, nil
	case *rsql.String:
		return v.Value, nil
	case *rsql.Bool:
		return v.Value, nil
	case *rsql.Null:
		return nil, nil
	}

	return nil, nil
}

type Like struct {
	column string
	value  string
}

func (l Like) ToSql() (sql string, args []interface{}, err error) {
	sql = fmt.Sprintf("%s LIKE(?)", l.column)
	args = append(args, l.value)
	return
}