/*
 * Copyright 2010 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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 com.google.template.soy.soytree;

import com.google.common.collect.ImmutableList;
import com.google.template.soy.base.SourceLocation;
import com.google.template.soy.basetree.CopyState;
import com.google.template.soy.exprparse.ExpressionParser;
import com.google.template.soy.exprparse.SoyParsingContext;
import com.google.template.soy.exprtree.ExprNode;
import com.google.template.soy.exprtree.ExprRootNode;
import com.google.template.soy.soytree.SoyNode.ExprHolderNode;
import com.google.template.soy.soytree.SoyNode.MsgSubstUnitNode;
import com.google.template.soy.soytree.SoyNode.SplitLevelTopNode;

import java.util.List;

import javax.annotation.Nullable;

/**
 * Node representing a 'select' block.
 *
 * <p> Important: Do not use outside of Soy code (treat as superpackage-private).
 *
 */
public final class MsgSelectNode extends AbstractParentCommandNode<CaseOrDefaultNode>
    implements MsgSubstUnitNode, SplitLevelTopNode<CaseOrDefaultNode>, ExprHolderNode {


  /** Fallback base select var name. */
  public static final String FALLBACK_BASE_SELECT_VAR_NAME = "STATUS";


  /** The expression for the value to select on. */
  private final ExprRootNode selectExpr;

  /** The base select var name (what the translator sees). */
  private final String baseSelectVarName;


  private MsgSelectNode(
      int id,
      String commandText,
      ExprRootNode selectExpr,
      SourceLocation sourceLocation) {
    super(id, sourceLocation, "select", commandText);

    this.selectExpr = selectExpr;

    // TODO: Maybe allow user to write 'phname' attribute in 'select' tag.
    // Note: If we do add support for 'phname' for 'select', it would also be a good time to clean
    // up how 'phname' is parsed for 'call'. Right now, it's parsed in TemplateParser.jj because
    // 'print' needs it to be parsed in TemplateParser.jj (due to print directives possibly
    // appearing between the expression and the 'phname' attribute). But for 'call', it should
    // really be parsed in CallNode.
    baseSelectVarName =
        MsgSubstUnitBaseVarNameUtils.genNaiveBaseNameForExpr(
            selectExpr.getRoot(), FALLBACK_BASE_SELECT_VAR_NAME);
  }


  /**
   * @param id The id for this node.
   * @param sourceLocation The node's source location.
   * @param selectExpr The expression for the value to select on.
   * @param baseSelectVarName The base select var name to use (what the translator sees), or null if
   *     it should be generated from the select expression.
   */
  public MsgSelectNode(
      int id,
      SourceLocation sourceLocation,
      ExprRootNode selectExpr,
      @Nullable String baseSelectVarName) {
    super(id, sourceLocation, "select",
        selectExpr.toSourceString() +
            ((baseSelectVarName != null) ? " phname=\"" + baseSelectVarName + "\"" : ""));
    this.selectExpr = selectExpr;
    this.baseSelectVarName = (baseSelectVarName != null) ? baseSelectVarName :
        MsgSubstUnitBaseVarNameUtils.genNaiveBaseNameForExpr(
            selectExpr.getRoot(), FALLBACK_BASE_SELECT_VAR_NAME);
  }


  /**
   * Copy constructor.
   * @param orig The node to copy.
   */
  private MsgSelectNode(MsgSelectNode orig, CopyState copyState) {
    super(orig, copyState);
    this.selectExpr = orig.selectExpr.copy(copyState);
    this.baseSelectVarName = orig.baseSelectVarName;
  }


  @Override public Kind getKind() {
    return Kind.MSG_SELECT_NODE;
  }


  /** Returns the expression for the value to select on. */
  public ExprRootNode getExpr() {
    return selectExpr;
  }


  /** Returns the base select var name (what the translator sees). */
  @Override public String getBaseVarName() {
    return baseSelectVarName;
  }


  @Override public boolean shouldUseSameVarNameAs(MsgSubstUnitNode other) {
    return (other instanceof MsgSelectNode) &&
        this.getCommandText().equals(((MsgSelectNode) other).getCommandText());
  }


  @Override public List<ExprUnion> getAllExprUnions() {
    return ImmutableList.of(new ExprUnion(selectExpr));
  }


  @Override public MsgBlockNode getParent() {
    return (MsgBlockNode) super.getParent();
  }


  @Override public MsgSelectNode copy(CopyState copyState) {
    return new MsgSelectNode(this, copyState);
  }

  /**
   * Builder for {@link MsgSelectNode}.
   */
  public static final class Builder {
    private final int id;
    private final String commandText;
    private final SourceLocation sourceLocation;

    /**
     * @param id The node's id.
     * @param commandText The node's command text.
     * @param sourceLocation The node's source location.
     */
    public Builder(int id, String commandText, SourceLocation sourceLocation) {
      this.id = id;
      this.commandText = commandText;
      this.sourceLocation = sourceLocation;
    }

    /**
     * Returns a new {@link MsgSelectNode} built from this builder's state, reporting syntax errors
     * to the given {@link ErrorReporter}.
     */
    public MsgSelectNode build(SoyParsingContext context) {
      ExprNode selectExpr = new ExpressionParser(commandText, sourceLocation, context)
          .parseExpression();
      return new MsgSelectNode(id, commandText, new ExprRootNode(selectExpr), sourceLocation);
    }
  }

}