// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.schema.processing;

import com.yahoo.config.application.api.DeployLogger;
import com.yahoo.schema.RankProfileRegistry;
import com.yahoo.schema.Schema;
import com.yahoo.schema.document.SDField;
import com.yahoo.vespa.indexinglanguage.ExpressionConverter;
import com.yahoo.vespa.indexinglanguage.ExpressionVisitor;
import com.yahoo.vespa.indexinglanguage.expressions.Expression;
import com.yahoo.vespa.indexinglanguage.expressions.InputExpression;
import com.yahoo.vespa.indexinglanguage.expressions.ScriptExpression;
import com.yahoo.vespa.indexinglanguage.expressions.StatementExpression;
import com.yahoo.vespa.model.container.search.QueryProfiles;

/**
 * This processor modifies all indexing scripts so that they input the value of the owning field by default. It also
 * ensures that all fields used as input exist.
 *
 * @author Simon Thoresen Hult
 */
public class IndexingInputs extends Processor {

    public IndexingInputs(Schema schema, DeployLogger deployLogger, RankProfileRegistry rankProfileRegistry, QueryProfiles queryProfiles) {
        super(schema, deployLogger, rankProfileRegistry, queryProfiles);
    }

    @Override
    public void process(boolean validate, boolean documentsOnly) {
        for (SDField field : schema.allConcreteFields()) {
            ScriptExpression script = field.getIndexingScript();
            if (script == null) continue;

            script = (ScriptExpression)new DefaultToCurrentField(field).convert(script);
            script = (ScriptExpression)new EnsureInputExpression(field).convert(script);
            if (validate)
                new VerifyInputExpression(schema, field).visit(script);

            field.setIndexingScript(script);
        }
    }

    private static class DefaultToCurrentField extends ExpressionConverter {

        final SDField field;

        DefaultToCurrentField(SDField field) {
            this.field = field;
        }

        @Override
        protected boolean shouldConvert(Expression exp) {
            return exp instanceof InputExpression && ((InputExpression)exp).getFieldName() == null;
        }

        @Override
        protected Expression doConvert(Expression exp) {
            return new InputExpression(field.getName());
        }
    }

    private static class EnsureInputExpression extends ExpressionConverter {

        final SDField field;

        EnsureInputExpression(SDField field) {
            this.field = field;
        }

        @Override
        protected boolean shouldConvert(Expression exp) {
            return exp instanceof StatementExpression
                   && ( field.isDocumentField() || ( field.getAttribute() != null && field.getAttribute().isMutable()));
        }

        @Override
        protected Expression doConvert(Expression exp) {
            if (exp.requiredInputType() != null) {
                return new StatementExpression(new InputExpression(field.getName()), exp);
            } else {
                return exp;
            }
        }
    }

    private class VerifyInputExpression extends ExpressionVisitor {

        private final Schema schema;
        private final SDField field;

        public VerifyInputExpression(Schema schema, SDField field) {
            this.schema = schema;
            this.field = field;
        }

        @Override
        protected void doVisit(Expression exp) {
            if ( ! (exp instanceof InputExpression)) return;
            var referencedFieldName = ((InputExpression)exp).getFieldName();
            var referencedField = schema.getField(referencedFieldName);
            if (referencedField == null || ! referencedField.hasFullIndexingDocprocRights())
                fail(schema, field, "Indexing script refers to field '" + referencedFieldName +
                                    "' which is neither a field in " + schema.getDocument() + " nor a mutable attribute");
        }
    }
}