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//: Copyright Verizon Media

//: Licensed under the terms of the Apache 2.0 License. See LICENSE file in the project root for terms.

package vssh

import (

"context"

"errors"

"fmt"

"go/ast"

"go/parser"

"strconv"

"sync"

"time"

)

const (

idLogic = iota

idOp

idName

idValue

idEvald

opAnd = 34

opOr = 35

)

var errNotSupportOperator = errors.New("operator doesn't support")

var errQuery = errors.New("query error")

type query struct {

cmd string

ctx context.Context

respChan chan *Response

respTimeout time.Duration

stmt string

compiledQuery *visitor

limitReadOut int64

limitReadErr int64

}

type visitor struct {

idents []ident

}

type ident struct {

value string

vType int

}

func (q *query) errResp(id string, err error) {

err = fmt.Errorf("client [%s]: %v", id, err)

q.respChan <- &Response{id: id, err: err}

}

func (q *query) run(v *VSSH) {

var wg sync.WaitGroup

for client := range v.clients.enum() {

client := client

wg.Add(1)

go func() {

defer wg.Done()

if len(q.stmt) > 0 && !client.labelMatch(q.compiledQuery) {

return

}

if v.mode {

client.connect()

}

if client.err != nil {

q.respChan <- &Response{err: client.err}

return

}

client.run(q)

if v.mode {

client.close()

}

}()

}

wg.Wait()

close(q.respChan)

}

func (f *visitor) Visit(n ast.Node) ast.Visitor {

switch d := n.(type) {

case *ast.Ident:

f.idents = append(f.idents, ident{d.Name, idName})

case *ast.BasicLit:

f.idents = append(f.idents, ident{d.Value, idValue})

case *ast.BinaryExpr:

if d.Op == opAnd || d.Op == opOr {

f.idents = append(f.idents, ident{d.Op.String(), idLogic})

} else {

f.idents = append(f.idents, ident{d.Op.String(), idOp})

}

}

return f

}

func parseExpr(expr string) (*visitor, error) {

e, err := parser.ParseExpr(expr)

if err != nil {

return nil, err

}

var v visitor

ast.Walk(&v, e)

return &v, nil

}

func exprEval(v *visitor, labels map[string]string) (bool, error) {

results := []ident{}

i := 0

for {

if len(v.idents[i:]) < 3 {

break

}

if v.idents[i].vType == 0 {

results = append(results, v.idents[i])

i++

continue

}

if relOpEval(v.idents[i:i+3], labels) {

results = append(results, ident{"true", idEvald})

} else {

results = append(results, ident{"false", idEvald})

}

if i+3 < len(v.idents) {

i = i + 3

} else {

break

}

}

if len(results) < 1 {

return false, errQuery

}

ok, err := binOpEval(&results)

if err != nil {

return ok, err

}

return ok, nil

}

func binOpEval(idents *[]ident) (bool, error) {

i := 0

for {

if len((*idents)) == 1 {

r, _ := strconv.ParseBool((*idents)[0].value)

return r, nil

}

if (*idents)[i].vType == 0 && (*idents)[i+1].vType == 0 {

i++

continue

}

if len((*idents)) > 2 && (*idents)[i].vType == idLogic &&

(*idents)[i+1].vType == idEvald && (*idents)[i+2].vType == idEvald {

r1, _ := strconv.ParseBool((*idents)[i+1].value)

r2, _ := strconv.ParseBool((*idents)[i+2].value)

if (*idents)[i].value == "&&" {

(*idents)[i].value = strconv.FormatBool(r1 && r2)

} else if (*idents)[i+0].value == "||" {

(*idents)[i].value = strconv.FormatBool(r1 || r2)

} else {

return false, errNotSupportOperator

}

(*idents)[i].vType = idEvald

if len((*idents)) > 2 {

(*idents) = append((*idents)[:i+1], (*idents)[i+3:]...)

i = 0

continue

} else {

tmp := (*idents)[0:1]

*idents = tmp

}

}

if len((*idents)) > 4 {

i += 2

} else {

return false, errNotSupportOperator

}

}

}

func relOpEval(idents []ident, labels map[string]string) bool {

if idents[0].value == "==" {

if _, ok := labels[idents[1].value]; ok {

return labels[idents[1].value] == idents[2].value

}

} else {

if _, ok := labels[idents[1].value]; ok {

return labels[idents[1].value] != idents[2].value

}

}

return false

}