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package com.oracle.js.parser.ir;

import java.util.List;

import com.oracle.js.parser.ir.visitor.NodeVisitor;
import com.oracle.js.parser.ir.visitor.TranslatorNodeVisitor;

/**
 * IR representation of a SWITCH statement.
 */
public final class SwitchNode extends BreakableStatement {
    /** Switch expression. */
    private final Expression expression;

    /** Switch cases. */
    private final List cases;

    /** Switch default index. */
    private final int defaultCaseIndex;

    /** Tag symbol. */
    private Symbol tag;

    /**
     * Constructor
     *
     * @param lineNumber lineNumber
     * @param token token
     * @param finish finish
     * @param expression switch expression
     * @param cases cases
     * @param defaultCaseIndex the default case index; -1 if none, otherwise has to be present in
     *            cases list
     */
    public SwitchNode(final int lineNumber, final long token, final int finish, final Expression expression, final List cases, final int defaultCaseIndex) {
        super(lineNumber, token, finish);
        this.expression = expression;
        this.cases = List.copyOf(cases);
        this.defaultCaseIndex = defaultCaseIndex;
        assert defaultCaseIndex == -1 || cases.get(defaultCaseIndex).getTest() == null;
    }

    private SwitchNode(final SwitchNode switchNode, final Expression expression, final List cases, final int defaultCaseIndex) {
        super(switchNode);
        this.expression = expression;
        this.cases = List.copyOf(cases);
        this.defaultCaseIndex = defaultCaseIndex;
        this.tag = switchNode.getTag(); // TODO are symbols inherited as references?
    }

    @Override
    public boolean isTerminal() {
        // there must be a default case, and that including all other cases must terminate
        if (!cases.isEmpty() && defaultCaseIndex != -1) {
            for (final CaseNode caseNode : cases) {
                if (!caseNode.isTerminal()) {
                    return false;
                }
            }
            return true;
        }
        return false;

    }

    @Override
    public Node accept(final LexicalContext lc, final NodeVisitor visitor) {
        if (visitor.enterSwitchNode(this)) {
            //@formatter:off
            return visitor.leaveSwitchNode(
                setExpression(lc, (Expression) expression.accept(visitor)).
                setCases(lc, Node.accept(visitor, cases), defaultCaseIndex));
            //@formatter:on
        }

        return this;
    }

    @Override
    public  R accept(LexicalContext lc, TranslatorNodeVisitor visitor) {
        return visitor.enterSwitchNode(this);
    }

    @Override
    public void toString(final StringBuilder sb, final boolean printType) {
        sb.append("switch (");
        expression.toString(sb, printType);
        sb.append(')');
    }

    /**
     * Return the case node that is default case
     *
     * @return default case or null if none
     */
    public CaseNode getDefaultCase() {
        return defaultCaseIndex == -1 ? null : cases.get(defaultCaseIndex);
    }

    /**
     * Get the cases in this switch
     *
     * @return a list of case nodes
     */
    public List getCases() {
        return cases;
    }

    private SwitchNode setCases(final LexicalContext lc, final List cases, final int defaultCaseIndex) {
        if (this.cases == cases) {
            return this;
        }
        return Node.replaceInLexicalContext(lc, this, new SwitchNode(this, expression, cases, defaultCaseIndex));
    }

    /**
     * Return the expression to switch on
     *
     * @return switch expression
     */
    public Expression getExpression() {
        return expression;
    }

    /**
     * Set or reset the expression to switch on
     *
     * @param lc lexical context
     * @param expression switch expression
     * @return new switch node or same if no state was changed
     */
    public SwitchNode setExpression(final LexicalContext lc, final Expression expression) {
        if (this.expression == expression) {
            return this;
        }
        return Node.replaceInLexicalContext(lc, this, new SwitchNode(this, expression, cases, defaultCaseIndex));
    }

    /**
     * Get the tag symbol for this switch. The tag symbol is where the switch expression result is
     * stored
     *
     * @return tag symbol
     */
    public Symbol getTag() {
        return tag;
    }

    /**
     * Set the tag symbol for this switch. The tag symbol is where the switch expression result is
     * stored
     *
     * @param tag a symbol
     */
    public void setTag(final Symbol tag) {
        this.tag = tag;
    }

    /**
     * @return true if this switch has a default case.
     */
    public boolean hasDefaultCase() {
        return defaultCaseIndex != -1;
    }

    @Override
    public boolean isCompletionValueNeverEmpty() {
        return true;
    }
}