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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.Item;
import swim.structure.Text;
import swim.structure.Value;
import swim.util.Log;

// TODO: consider making this capable of accepting dynamic arguments
//  (easy enough to do, but is it actually useful?)
public final class Substring extends Directive {

  private final int lower;
  private final int upper;

  public Substring(Directive parent, AgentContext context, Log log, Item scope,
                   int lower, int upper) {
    super(parent, context, log, scope);
    this.lower = lower;
    this.upper = upper;
  }

  static Substring fromSchema(Directive parent, AgentContext context, Log log, Item scope,
                              Value schema) {
    return new Substring(parent, context, log, scope,
        schema.get("lower").intValue(-1),
        schema.get("upper").intValue(-1));
  }

  @Override
  public Text evaluate() throws InterpretException {
    final String str;
    try {
      str = this.scope.stringValue();
    } catch (RuntimeException e) {
      final String msg = "scope " + this.scope + " does not have a String representation;"
          + " consider adding a coercion-type Directive";
      throw new InterpretException(msg, e);
    }
    try {
      if (this.lower < 0) {
        if (this.upper < 0) {
          return Text.from(str);
        } else {
          return Text.from(str.substring(0, this.upper));
        }
      } else if (this.upper < 0) {
        return Text.from(str.substring(this.lower));
      } else {
        return Text.from(str.substring(this.lower, this.upper));
      }
    } catch (RuntimeException e) {
      final String msg = "Unsuitable bounds [" + Math.max(this.lower, 0) + ","
          + (this.upper < 0 ? str.length() : this.upper) + ") provided for scope " + str;
      throw new InterpretException(msg, e);
    }
  }

  @Override
  public String toString() {
    return "Substring{"
        + "scope=" + this.scope
        + (this.lower < 0 ? "" : ", lower=" + this.lower)
        + (this.upper < 0 ? "" : ", upper=" + this.upper)
        + '}';
  }

}