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workflow.go
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workflow.go
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package workflow
import (
"errors"
)
type (
Step struct {
NodeID string `json:"nID"`
HierarchyPath string `json:"wfID"`
Name string `json:"name"`
Type string `json:"type"`
Detail string `json:"detail,omitempty"`
}
Stack struct {
Node *Node
}
Workflow struct {
Flow *Flow `json:"flow"`
}
Flow struct {
Start *Start `json:"start"`
Nodes map[string]*Node `json:"nodes"`
}
Position struct {
X float64 `json:"x"`
Y float64 `json:"y"`
}
Start struct {
NodeID string `json:"node"`
Position Position `json:"p"`
}
Case struct {
Name string `json:"name"`
Value interface{} `json:"value"`
Detail string `json:"detail,omitempty"`
Data map[string]interface{} `json:"data,omitempty"`
}
Connection struct {
NodeID string `json:"id"`
CaseValue interface{} `json:"value,omitempty"`
}
//ensures entities are looped once to prevent from an endless loop in nested patterns
Looper struct {
accessedOnes map[string]bool
cb LooperCallback
}
LooperCallback func(l *Looper, node *Node) bool
context struct {
id string
flow *Flow
current string
hasNext bool
children map[string]*context
parent *context
engine *Engine
}
)
var (
ErrWorkflowMissing = errors.New("cannot run without Workflow")
ErrStartNodeMissing = errors.New("cannot run without the start node")
ErrConditionDataMissing = errors.New("condition data missing")
ErrConditionCaseConnection = errors.New("condition cases are not leading in any case to a node")
ErrConditionConnectionsMissing = errors.New("condition connections missing")
ErrNotExist = errors.New("does not exist")
ErrConfigGetWorkflowMissing = errors.New("GetWorkflow missing in your config")
ErrNodeImplementationNotProvided = errors.New("node impl not provided")
)
func newWorkflow(wf *Workflow, engine *Engine, parent *context) (*context, error) {
if wf == nil {
return nil, ErrWorkflowMissing
}
if wf.Flow == nil || wf.Flow.Start == nil || wf.Flow.Start.NodeID == "" {
return nil, ErrStartNodeMissing
}
me := context{
id: "root",
flow: wf.Flow,
hasNext: true,
parent: parent,
engine: engine,
}
err := engine.removeUselessNodes(&me)
if err != nil {
return nil, err
}
err = engine.setupNodes(&me)
if err != nil {
return nil, err
}
me.start()
return &me, nil
}
func (me *context) start() {
me.engine.target = me
me.current = me.flow.Start.NodeID
}
func (me *context) curr() (n *Node, err error) {
n = me.getCurrent()
if n != nil {
if n.err != nil {
err = n.err
}
} else {
err = ErrNotExist
}
return
}
func (me *context) end() {
me.hasNext = false
}
func (me *context) resolve(n *Node) error {
if n != nil {
if n.internalNode {
if n.isCondition() {
nn, err := me.condition(n)
if err != nil {
return err
}
return me.resolve(nn)
} else if n.isPlaceholder() {
return nil
} else if n.isWorkflow() {
return me.stepIntoWorkflow(n)
}
} else {
var proceed bool
var err error
proceed, err = me.engine.execute(n, true)
if err != nil {
return err
}
if proceed {
n.resetState()
if me.hasNext = len(n.Connections) > 0; me.hasNext {
con := n.Connections[0]
if con != nil {
return me.resolve(me.getNode(&con.NodeID))
}
}
} else {
return nil
}
}
}
if n == nil {
n = me.getCurrent()
}
if me.isNotRoot() { //step out of workflow
me.end()
n.resetState()
t := me.parent
tn := t.getCurrent()
for {
if t.hasNext = len(tn.Connections) > 0; t.hasNext {
con := tn.Connections[0]
if con != nil {
return t.resolve(t.getNode(&con.NodeID))
}
} else if t.isNotRoot() {
t = t.parent
tn = t.getCurrent()
} else {
break
}
}
return nil
}
me.end()
n.resetState()
return nil
}
func (me *context) isNotRoot() bool {
return me.parent != nil
}
func (me *context) getCurrent() *Node {
return me.getNode(&me.current)
}
func (me *context) getNode(id *string) *Node {
return me.flow.Nodes[*id]
}
func (me *context) condition(n *Node) (*Node, error) {
if len(n.Connections) > 0 {
n.err = nil
if n.Data == nil {
n.err = ErrConditionDataMissing
return nil, n.err
}
jScript, ok := n.Data["js"].(string)
if ok && jScript != "" {
err := me.engine.setJSGlobalData()
if err != nil {
n.err = err
return nil, err
}
jScript = jScript + "; if(!input){input={};}condition();"
v, err := me.engine.jsEval(&jScript)
var caseValue interface{}
if err != nil {
n.err = err
return nil, err
}
if v.IsNumber() {
caseValue, err = v.ToFloat()
} else {
caseValue, err = v.Export()
}
if err != nil {
n.err = err
return nil, err
}
me.engine.execute(n, false)
for _, conn := range n.Connections {
if conn != nil && conn.CaseValue == caseValue {
return me.getNode(&conn.NodeID), nil
}
}
n.err = ErrConditionCaseConnection
return nil, n.err
} else {
n.err = ErrConditionDataMissing
return nil, n.err
}
} else {
n.err = ErrConditionConnectionsMissing
return nil, n.err
}
}
func (me *context) stepIntoWorkflow(n *Node) error {
n.err = nil
var newContext *context
if me.children == nil {
me.children = make(map[string]*context)
} else {
newContext = me.children[n.ID]
}
if newContext == nil {
if me.engine.getWorkflow == nil {
n.err = ErrConfigGetWorkflowMissing
return n.err
}
var wf *Workflow
wf, n.err = me.engine.getWorkflow(n.ID)
if n.err != nil {
return n.err
}
me.engine.execute(n, false)
newContext, n.err = newWorkflow(wf, me.engine, me)
if n.err != nil {
return n.err
}
newContext.id = n.ID
me.children[n.ID] = newContext
} else {
//reuse embedded context
me.engine.execute(n, false)
newContext.start()
}
return newContext.resolve(newContext.getCurrent())
}
func (me *Flow) close() {
for _, v := range me.Nodes {
if v != nil {
v.close()
}
}
}
// Loop is making node loops easier
// looper keeps track of accessed entities, cb can be nil after the first call to simplify nested calls
func (me *Workflow) Loop(looper *Looper, cb LooperCallback) {
if looper != nil && looper.accessedOnes == nil {
looper.accessedOnes = map[string]bool{}
}
for k, v := range me.Flow.Nodes {
if looper != nil {
if looper.accessedOnes[k] {
continue
}
looper.accessedOnes[k] = true
if cb == nil {
cb = looper.cb
} else if looper.cb == nil {
looper.cb = cb
}
}
if cb == nil {
break
}
if !cb(looper, v) {
break
}
}
}
func (me *context) close() {
if me.flow != nil {
me.flow.close()
}
for _, v := range me.children {
if v != nil {
v.close()
}
}
me.children = nil
me.parent = nil
me.engine = nil
}