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// Copyright 2015-2024 Nstream, inc.
//
// Licensed under the Redis Source Available License 2.0 (RSALv2) Agreement;
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://redis.com/legal/rsalv2-agreement/
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package nstream.adapter.common.relay;

import swim.api.agent.AgentContext;
import swim.structure.Bool;
import swim.structure.Item;
import swim.structure.Value;
import swim.util.Log;

/**
 * {@code Directive} to conditionally invoke logic.
 */
public final class If extends Directive {

  private final Value condition;
  private final Value conditionLiteral;
  private final Value then;
  private final Value thenLiteral;
  private final Value orElse;
  private final Value orElseLiteral;

  public If(Directive parent, AgentContext context, Log log, Item scope,
            Value condition, Value conditionLiteral,
            Value then, Value thenLiteral,
            Value orElse, Value orElseLiteral) {
    super(parent, context, log, scope);
    this.condition = condition;
    this.conditionLiteral = conditionLiteral;
    this.then = then;
    this.thenLiteral = thenLiteral;
    this.orElse = orElse;
    this.orElseLiteral = orElseLiteral;
  }

  static If fromSchema(Directive parent, AgentContext context, Log log, Item scope,
                       Value schema) {
    return new If(parent, context, log, scope,
        schema.get("condition"), schema.get("conditionLiteral"),
        schema.get("then"), schema.get("thenLiteral"),
        schema.get("else"), schema.get("elseLiteral"));
  }

  @Override
  public Value evaluate() throws InterpretException {
    final Value condVal = DslInterpret.evaluateHintedValue(this, this.condition, this.conditionLiteral, "condition");
    if (condVal == null || !condVal.isDefined()) {
      throw new InterpretException("Evaluated undefined condition " + condVal);
    }
    final boolean cond;
    try {
      final Bool mayThrow = (Bool) condVal;
      cond = mayThrow.booleanValue();
    } catch (RuntimeException e) {
      throw new InterpretException("Evaluated condition " + condVal + " does not yield boolean", e);
    }
    return cond ? DslInterpret.evaluateHintedValue(this, this.then, this.thenLiteral, "then")
        : DslInterpret.evaluateHintedValue(this, this.orElse, this.orElseLiteral, "else");
  }

  @Override
  public String toString() {
    return "If{"
        + hintOrLiteralToString(this.condition, this.conditionLiteral, "condition", true)
        + hintOrLiteralToString(this.then, this.thenLiteral, "then")
        + hintOrLiteralToString(this.orElse, this.orElseLiteral, "else")
        + '}';
  }

}