feat: policy evaluation plan (eclipse-edc#4442)

* feat: policy evaluation plan

core/common/lib/policy-engine-lib/src/main/java/org/eclipse/edc/policy/engine/PolicyEngineImpl.java

@@ -14,11 +14,13 @@
 
 package org.eclipse.edc.policy.engine;
 
+import org.eclipse.edc.policy.engine.plan.PolicyEvaluationPlanner;
 import org.eclipse.edc.policy.engine.spi.AtomicConstraintFunction;
 import org.eclipse.edc.policy.engine.spi.DynamicAtomicConstraintFunction;
 import org.eclipse.edc.policy.engine.spi.PolicyContext;
 import org.eclipse.edc.policy.engine.spi.PolicyEngine;
 import org.eclipse.edc.policy.engine.spi.RuleFunction;
+import org.eclipse.edc.policy.engine.spi.plan.PolicyEvaluationPlan;
 import org.eclipse.edc.policy.engine.validation.PolicyValidator;
 import org.eclipse.edc.policy.engine.validation.RuleValidator;
 import org.eclipse.edc.policy.evaluator.PolicyEvaluator;
@@ -48,7 +50,7 @@
  */
 public class PolicyEngineImpl implements PolicyEngine {
 
-    private static final String ALL_SCOPES_DELIMITED = ALL_SCOPES + DELIMITER;
+    public static final String ALL_SCOPES_DELIMITED = ALL_SCOPES + DELIMITER;
 
     private final Map<String, List<ConstraintFunctionEntry<Rule>>> constraintFunctions = new TreeMap<>();
 
@@ -65,6 +67,10 @@ public PolicyEngineImpl(ScopeFilter scopeFilter, RuleValidator ruleValidator) {
         this.ruleValidator = ruleValidator;
     }
 
+    public static boolean scopeFilter(String entry, String scope) {
+        return ALL_SCOPES_DELIMITED.equals(entry) || scope.startsWith(entry);
+    }
+
     @Override
     public Policy filter(Policy policy, String scope) {
         return scopeFilter.applyScope(policy, scope);
@@ -148,6 +154,29 @@ public Result<Void> validate(Policy policy) {
         return validatorBuilder.build().validate(policy);
     }
 
+    @Override
+    public PolicyEvaluationPlan createEvaluationPlan(String scope, Policy policy) {
+        var delimitedScope = scope + DELIMITER;
+        var planner = PolicyEvaluationPlanner.Builder.newInstance(delimitedScope).ruleValidator(ruleValidator);
+
+        preValidators.forEach(planner::preValidators);
+        postValidators.forEach(planner::postValidators);
+
+        constraintFunctions.forEach((functionScope, entry) -> entry.forEach(constraintEntry -> {
+            planner.evaluationFunction(functionScope, constraintEntry.key, constraintEntry.type, constraintEntry.function);
+        }));
+
+        dynamicConstraintFunctions.forEach(dynFunctions ->
+                planner.evaluationFunction(dynFunctions.scope, dynFunctions.type, dynFunctions.function)
+        );
+
+        ruleFunctions.forEach((functionScope, entry) -> entry.forEach(functionEntry -> {
+            planner.evaluationFunction(functionScope, functionEntry.type, functionEntry.function);
+        }));
+
+        return policy.accept(planner.build());
+    }
+
     @Override
     @SuppressWarnings({ "unchecked", "rawtypes" })
     public <R extends Rule> void registerFunction(String scope, Class<R> type, String key, AtomicConstraintFunction<R> function) {
@@ -176,10 +205,6 @@ public void registerPostValidator(String scope, BiFunction<Policy, PolicyContext
         postValidators.computeIfAbsent(scope + DELIMITER, k -> new ArrayList<>()).add(validator);
     }
 
-    private boolean scopeFilter(String entry, String scope) {
-        return ALL_SCOPES_DELIMITED.equals(entry) || scope.startsWith(entry);
-    }
-
     @NotNull
     private Result<Void> failValidator(String type, BiFunction<Policy, PolicyContext, Boolean> validator, PolicyContext context) {
         return failure(context.hasProblems() ? context.getProblems() : List.of(type + " failed: " + validator.getClass().getName()));

core/common/lib/policy-engine-lib/src/main/java/org/eclipse/edc/policy/engine/plan/PolicyEvaluationPlanner.java

@@ -0,0 +1,314 @@
+/*
+ *  Copyright (c) 2024 Bayerische Motoren Werke Aktiengesellschaft (BMW AG)
+ *
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Apache License, Version 2.0 which is available at
+ *  https://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Contributors:
+ *       Bayerische Motoren Werke Aktiengesellschaft (BMW AG) - initial API and implementation
+ *
+ */
+
+package org.eclipse.edc.policy.engine.plan;
+
+import org.eclipse.edc.policy.engine.spi.AtomicConstraintFunction;
+import org.eclipse.edc.policy.engine.spi.DynamicAtomicConstraintFunction;
+import org.eclipse.edc.policy.engine.spi.PolicyContext;
+import org.eclipse.edc.policy.engine.spi.RuleFunction;
+import org.eclipse.edc.policy.engine.spi.plan.PolicyEvaluationPlan;
+import org.eclipse.edc.policy.engine.spi.plan.step.AndConstraintStep;
+import org.eclipse.edc.policy.engine.spi.plan.step.AtomicConstraintStep;
+import org.eclipse.edc.policy.engine.spi.plan.step.ConstraintStep;
+import org.eclipse.edc.policy.engine.spi.plan.step.DutyStep;
+import org.eclipse.edc.policy.engine.spi.plan.step.OrConstraintStep;
+import org.eclipse.edc.policy.engine.spi.plan.step.PermissionStep;
+import org.eclipse.edc.policy.engine.spi.plan.step.ProhibitionStep;
+import org.eclipse.edc.policy.engine.spi.plan.step.RuleFunctionStep;
+import org.eclipse.edc.policy.engine.spi.plan.step.RuleStep;
+import org.eclipse.edc.policy.engine.spi.plan.step.ValidatorStep;
+import org.eclipse.edc.policy.engine.spi.plan.step.XoneConstraintStep;
+import org.eclipse.edc.policy.engine.validation.RuleValidator;
+import org.eclipse.edc.policy.model.AndConstraint;
+import org.eclipse.edc.policy.model.AtomicConstraint;
+import org.eclipse.edc.policy.model.Constraint;
+import org.eclipse.edc.policy.model.Duty;
+import org.eclipse.edc.policy.model.MultiplicityConstraint;
+import org.eclipse.edc.policy.model.Operator;
+import org.eclipse.edc.policy.model.OrConstraint;
+import org.eclipse.edc.policy.model.Permission;
+import org.eclipse.edc.policy.model.Policy;
+import org.eclipse.edc.policy.model.Prohibition;
+import org.eclipse.edc.policy.model.Rule;
+import org.eclipse.edc.policy.model.XoneConstraint;
+import org.eclipse.edc.spi.result.Result;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Stack;
+import java.util.TreeMap;
+import java.util.function.BiFunction;
+import java.util.stream.Collectors;
+
+import static org.eclipse.edc.policy.engine.PolicyEngineImpl.scopeFilter;
+
+public class PolicyEvaluationPlanner implements Policy.Visitor<PolicyEvaluationPlan>, Rule.Visitor<RuleStep<? extends Rule>>, Constraint.Visitor<ConstraintStep> {
+
+    private final Stack<Rule> ruleContext = new Stack<>();
+    private final List<BiFunction<Policy, PolicyContext, Boolean>> preValidators = new ArrayList<>();
+    private final List<BiFunction<Policy, PolicyContext, Boolean>> postValidators = new ArrayList<>();
+    private final Map<String, List<ConstraintFunctionEntry<Rule>>> constraintFunctions = new TreeMap<>();
+    private final List<DynamicAtomicConstraintFunctionEntry<Rule>> dynamicConstraintFunctions = new ArrayList<>();
+    private final List<RuleFunctionFunctionEntry<Rule>> ruleFunctions = new ArrayList<>();
+    private final String delimitedScope;
+
+    private RuleValidator ruleValidator;
+
+    private PolicyEvaluationPlanner(String delimitedScope) {
+        this.delimitedScope = delimitedScope;
+    }
+
+    @Override
+    public AndConstraintStep visitAndConstraint(AndConstraint constraint) {
+        var steps = validateMultiplicityConstraint(constraint);
+        return new AndConstraintStep(steps, constraint);
+    }
+
+    @Override
+    public OrConstraintStep visitOrConstraint(OrConstraint constraint) {
+        var steps = validateMultiplicityConstraint(constraint);
+        return new OrConstraintStep(steps, constraint);
+
+    }
+
+    @Override
+    public XoneConstraintStep visitXoneConstraint(XoneConstraint constraint) {
+        var steps = validateMultiplicityConstraint(constraint);
+        return new XoneConstraintStep(steps, constraint);
+    }
+
+    @Override
+    public AtomicConstraintStep visitAtomicConstraint(AtomicConstraint constraint) {
+        var currentRule = currentRule();
+        var leftValue = constraint.getLeftExpression().accept(s -> s.getValue().toString());
+        var function = getFunctions(leftValue, currentRule.getClass());
+        var isFiltered = !ruleValidator.isInScope(leftValue, delimitedScope) || function == null;
+
+        return new AtomicConstraintStep(constraint, isFiltered, currentRule, function);
+    }
+
+    @Override
+    public PolicyEvaluationPlan visitPolicy(Policy policy) {
+
+        var builder = PolicyEvaluationPlan.Builder.newInstance();
+
+        preValidators.stream().map(ValidatorStep::new).forEach(builder::preValidator);
+        postValidators.stream().map(ValidatorStep::new).forEach(builder::postValidator);
+
+        policy.getPermissions().stream().map(permission -> permission.accept(this))
+                .map(PermissionStep.class::cast)
+                .forEach(builder::permission);
+
+        policy.getObligations().stream().map(obligation -> obligation.accept(this))
+                .map(DutyStep.class::cast)
+                .forEach(builder::obligation);
+
+        policy.getProhibitions().stream().map(permission -> permission.accept(this))
+                .map(ProhibitionStep.class::cast)
+                .forEach(builder::prohibition);
+
+        return builder.build();
+    }
+
+    @Override
+    public PermissionStep visitPermission(Permission permission) {
+        var permissionStepBuilder = PermissionStep.Builder.newInstance();
+        visitRule(permission, permissionStepBuilder);
+
+        permission.getDuties().stream().map(this::visitDuty)
+                .forEach(permissionStepBuilder::dutyStep);
+
+        return permissionStepBuilder.build();
+    }
+
+    @Override
+    public ProhibitionStep visitProhibition(Prohibition prohibition) {
+        var prohibitionStepBuilder = ProhibitionStep.Builder.newInstance();
+        visitRule(prohibition, prohibitionStepBuilder);
+        return prohibitionStepBuilder.build();
+    }
+
+    @Override
+    public DutyStep visitDuty(Duty duty) {
+        var prohibitionStepBuilder = DutyStep.Builder.newInstance();
+        visitRule(duty, prohibitionStepBuilder);
+        return prohibitionStepBuilder.build();
+    }
+
+    private AtomicConstraintFunction<Rule> getFunctions(String key, Class<? extends Rule> ruleKind) {
+        return constraintFunctions.getOrDefault(key, new ArrayList<>())
+                .stream()
+                .filter(entry -> ruleKind.isAssignableFrom(entry.type()))
+                .map(entry -> entry.function)
+                .findFirst()
+                .or(() -> dynamicConstraintFunctions
+                        .stream()
+                        .filter(f -> ruleKind.isAssignableFrom(f.type))
+                        .filter(f -> f.function.canHandle(key))
+                        .map(entry -> wrapDynamicFunction(key, entry.function))
+                        .findFirst())
+                .orElse(null);
+    }
+
+    @SuppressWarnings({ "rawtypes", "unchecked" })
+    private <R extends Rule> void visitRule(R rule, RuleStep.Builder builder) {
+
+        try {
+            ruleContext.push(rule);
+            builder.filtered(shouldIgnoreRule(rule));
+            builder.rule(rule);
+
+            for (var functionEntry : ruleFunctions) {
+                if (rule.getClass().isAssignableFrom(functionEntry.type)) {
+                    builder.ruleFunction(new RuleFunctionStep(functionEntry.function, rule));
+                }
+            }
+
+            rule.getConstraints().stream()
+                    .map(constraint -> constraint.accept(this))
+                    .forEach(builder::constraint);
+
+        } finally {
+            ruleContext.pop();
+        }
+
+    }
+
+    private Rule currentRule() {
+        return ruleContext.peek();
+    }
+
+    private boolean shouldIgnoreRule(Rule rule) {
+        return rule.getAction() != null && !ruleValidator.isBounded(rule.getAction().getType());
+    }
+
+    private List<ConstraintStep> validateMultiplicityConstraint(MultiplicityConstraint multiplicityConstraint) {
+        return multiplicityConstraint.getConstraints()
+                .stream()
+                .map(c -> c.accept(this))
+                .collect(Collectors.toList());
+    }
+
+    private <R extends Rule> AtomicConstraintFunction<R> wrapDynamicFunction(String key, DynamicAtomicConstraintFunction<R> function) {
+        return new AtomicConstraintFunctionWrapper<>(key, function);
+    }
+
+    private record ConstraintFunctionEntry<R extends Rule>(
+            Class<R> type,
+            AtomicConstraintFunction<R> function) {
+    }
+
+    private record DynamicAtomicConstraintFunctionEntry<R extends Rule>(
+            Class<R> type,
+            DynamicAtomicConstraintFunction<R> function) {
+    }
+
+    private record RuleFunctionFunctionEntry<R extends Rule>(
+            Class<R> type,
+            RuleFunction<R> function) {
+    }
+
+    private record AtomicConstraintFunctionWrapper<R extends Rule>(
+            String leftOperand,
+            DynamicAtomicConstraintFunction<R> inner) implements AtomicConstraintFunction<R> {
+
+        @Override
+        public boolean evaluate(Operator operator, Object rightValue, R rule, PolicyContext context) {
+            return inner.evaluate(leftOperand, operator, rightValue, rule, context);
+        }
+
+        @Override
+        public Result<Void> validate(Operator operator, Object rightValue, R rule) {
+            return inner.validate(leftOperand, operator, rightValue, rule);
+        }
+    }
+
+    public static class Builder {
+        private final PolicyEvaluationPlanner planner;
+
+        private Builder(String scope) {
+            planner = new PolicyEvaluationPlanner(scope);
+        }
+
+        public static PolicyEvaluationPlanner.Builder newInstance(String scope) {
+            return new PolicyEvaluationPlanner.Builder(scope);
+        }
+
+        public Builder ruleValidator(RuleValidator ruleValidator) {
+            planner.ruleValidator = ruleValidator;
+            return this;
+        }
+
+        public Builder preValidator(String scope, BiFunction<Policy, PolicyContext, Boolean> validator) {
+
+            if (scopeFilter(scope, planner.delimitedScope)) {
+                planner.preValidators.add(validator);
+            }
+
+            return this;
+        }
+
+        public Builder preValidators(String scope, List<BiFunction<Policy, PolicyContext, Boolean>> validators) {
+            validators.forEach(validator -> preValidator(scope, validator));
+            return this;
+        }
+
+        public Builder postValidator(String scope, BiFunction<Policy, PolicyContext, Boolean> validator) {
+            if (scopeFilter(scope, planner.delimitedScope)) {
+                planner.postValidators.add(validator);
+            }
+            return this;
+        }
+
+        public Builder postValidators(String scope, List<BiFunction<Policy, PolicyContext, Boolean>> validators) {
+            validators.forEach(validator -> postValidator(scope, validator));
+            return this;
+        }
+
+        @SuppressWarnings({ "unchecked", "rawtypes" })
+        public <R extends Rule> Builder evaluationFunction(String scope, String key, Class<R> ruleKind, AtomicConstraintFunction<R> function) {
+
+            if (scopeFilter(scope, planner.delimitedScope)) {
+                planner.constraintFunctions.computeIfAbsent(key, k -> new ArrayList<>())
+                        .add(new ConstraintFunctionEntry(ruleKind, function));
+            }
+            return this;
+        }
+
+        @SuppressWarnings({ "unchecked", "rawtypes" })
+        public <R extends Rule> Builder evaluationFunction(String scope, Class<R> ruleKind, DynamicAtomicConstraintFunction<R> function) {
+            if (scopeFilter(scope, planner.delimitedScope)) {
+                planner.dynamicConstraintFunctions.add(new DynamicAtomicConstraintFunctionEntry(ruleKind, function));
+            }
+            return this;
+        }
+
+        @SuppressWarnings({ "unchecked", "rawtypes" })
+        public <R extends Rule> Builder evaluationFunction(String scope, Class<R> ruleKind, RuleFunction<R> function) {
+            if (scopeFilter(scope, planner.delimitedScope)) {
+                planner.ruleFunctions.add(new RuleFunctionFunctionEntry(ruleKind, function));
+            }
+            return this;
+        }
+
+        public PolicyEvaluationPlanner build() {
+            Objects.requireNonNull(planner.ruleValidator, "Rule validator should not be null");
+            return planner;
+        }
+
+    }
+}