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package io.nflow.engine.workflow.definition;
import static java.lang.String.format;
import static java.util.Collections.emptyMap;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import org.springframework.util.Assert;
import io.nflow.engine.internal.workflow.WorkflowDefinitionScanner;
import io.nflow.engine.internal.workflow.WorkflowStateMethod;
import io.nflow.engine.model.ModelObject;
import io.nflow.engine.workflow.instance.WorkflowInstance;
/**
* The base class for all workflow definitions.
*/
public abstract class AbstractWorkflowDefinition extends ModelObject {
private final String type;
private String name;
private String description;
private final S initialState;
private final S errorState;
private final WorkflowSettings settings;
protected final Map> allowedTransitions = new LinkedHashMap<>();
protected final Map failureTransitions = new LinkedHashMap<>();
private Map stateMethods;
protected AbstractWorkflowDefinition(String type, S initialState, S errorState) {
this(type, initialState, errorState, new WorkflowSettings.Builder().build());
}
protected AbstractWorkflowDefinition(String type, S initialState, S errorState, WorkflowSettings settings) {
this(type, initialState, errorState, settings, null);
}
protected AbstractWorkflowDefinition(String type, S initialState, S errorState, WorkflowSettings settings,
Map stateMethods) {
Assert.notNull(initialState, "initialState must not be null");
Assert.isTrue(initialState.getType() == WorkflowStateType.start, "initialState must be a start state");
Assert.notNull(errorState, "errorState must not be null");
this.type = type;
this.initialState = initialState;
this.errorState = errorState;
this.settings = settings;
if (stateMethods != null) {
this.stateMethods = stateMethods;
} else {
this.stateMethods = new WorkflowDefinitionScanner().getStateMethods(getClass());
}
requireStateMethodExists(initialState);
}
/**
* Return the name of the workflow.
* @return The name.
*/
public String getName() {
return name;
}
/**
* Set the name of the workflow.
* @param name The name.
*/
public void setName(String name) {
this.name = name;
}
/**
* Return the description of the workflow.
* @return The description.
*/
public String getDescription() {
return description;
}
/**
* Set the description of the workflow.
* @param description The description.
*/
public void setDescription(String description) {
this.description = description;
}
/**
* Return the type of the workflow.
* @return The type.
*/
public String getType() {
return type;
}
/**
* Return the initial state of the workflow.
* @return Workflow state.
*/
public S getInitialState() {
return initialState;
}
/**
* Return the generic error state of the workflow.
* @return Workflow state.
*/
public S getErrorState() {
return errorState;
}
/**
* Return all possible states of the workflow.
* @return Set of workflow states.
*/
public abstract Set getStates();
/**
* Return allowed transitions between the states of the workflow.
* @return Map from origin states to a list of target states.
*/
public Map> getAllowedTransitions() {
return new LinkedHashMap<>(allowedTransitions);
}
/**
* Return transitions from states to failure states.
* @return Map from origin state to failure state.
*/
public Map getFailureTransitions() {
return new LinkedHashMap<>(failureTransitions);
}
/**
* Add a state transition to the allowed transitions.
* @param originState The origin state.
* @param targetState The target state.
* @return This.
*/
protected AbstractWorkflowDefinition permit(S originState, S targetState) {
requireStateMethodExists(originState);
requireStateMethodExists(targetState);
allowedTransitionsFor(originState).add(targetState.name());
return this;
}
/**
* Add a state and failure state transitions to the allowed transitions.
* @param originState The origin state.
* @param targetState The target state.
* @param failureState The failure state.
* @return This.
*/
protected AbstractWorkflowDefinition permit(S originState, S targetState, S failureState) {
Assert.notNull(failureState, "Failure state can not be null");
requireStateMethodExists(failureState);
WorkflowState existingFailure = failureTransitions.put(originState.name(), failureState);
Assert.isTrue(existingFailure == null || existingFailure.equals(failureState), "Different failureState '" + existingFailure
+ "' already defined for originState '" + originState.name() + "'");
return permit(originState, targetState);
}
private List allowedTransitionsFor(S state) {
String stateName = state.name();
List transitions = allowedTransitions.get(stateName);
if (transitions == null) {
transitions = new ArrayList<>();
allowedTransitions.put(stateName, transitions);
}
return transitions;
}
/**
* Return the workflow settings.
* @return Workflow settings.
*/
public WorkflowSettings getSettings() {
return settings;
}
final void requireStateMethodExists(S state) {
WorkflowStateMethod stateMethod = stateMethods.get(state.name());
if (stateMethod == null && !state.getType().isFinal()) {
String msg = format(
"Class '%s' is missing non-final state handling method 'public NextAction %s(StateExecution execution, ... args)'",
this.getClass().getName(), state.name());
throw new IllegalArgumentException(msg);
}
if (stateMethod != null) {
WorkflowStateType stateType = state.getType();
Class returnType = stateMethod.method.getReturnType();
if (!stateType.isFinal() && !NextAction.class.equals(returnType)) {
String msg = format("Class '%s' has a non-final state method '%s' that does not return NextAction", this.getClass()
.getName(), state.name());
throw new IllegalArgumentException(msg);
}
if (stateType.isFinal() && !Void.TYPE.equals(returnType)) {
String msg = format("Class '%s' has a final state method '%s' that returns a value", this.getClass().getName(),
state.name());
throw new IllegalArgumentException(msg);
}
}
}
/**
* Returns the workflow state method for the given state name.
* @param stateName The name of the workflow state.
* @return The workflow state method, or null if not found.
*/
public WorkflowStateMethod getMethod(String stateName) {
return stateMethods.get(stateName);
}
/**
* Returns the workflow state for the given state name.
*
* @param state
* The name of the workflow state.
* @return The workflos state matching the state name.
* @throws IllegalArgumentException
* when a matching state can not be found.
*/
public WorkflowState getState(String state) {
return getStates().stream().filter(s -> Objects.equals(s.name(), state)).findFirst()
.orElseThrow(() -> new IllegalArgumentException("No state '" + state + "' in workflow definiton " + getType()));
}
/**
* Check if the given state is a valid start state.
*
* @param state
* The name of the workflow state.
* @return True if the given state is a valid start date, false otherwise.
* @throws IllegalArgumentException
* if the given state name does not match any state.
*/
public boolean isStartState(String state) {
return getState(state).getType() == WorkflowStateType.start;
}
/**
* Return true if the given nextAction is permitted for given instance.
* @param instance The workflow instance for which the action is checked.
* @param nextAction The action to be checked.
* @return True if the nextAction is permitted, false otherwise.
*/
public boolean isAllowedNextAction(WorkflowInstance instance, NextAction nextAction) {
if (nextAction.isRetry()) {
return true;
}
List allowedNextStates = allowedTransitions.get(instance.state);
if (allowedNextStates != null && allowedNextStates.contains(nextAction.getNextState().name())) {
return true;
}
if (nextAction.getNextState() == failureTransitions.get(instance.state)) {
return true;
}
return nextAction.getNextState() == getErrorState();
}
/**
* Return signals supported by this workflow. Default implementation returns empty map, override this in your workflow
* definition that supports signals.
*
* @return Signals and their descriptions.
*/
public Map getSupportedSignals() {
return emptyMap();
}
}
