/*
 * 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 org.jdbi.v3.core.statement;

import java.util.ArrayList;
import java.util.List;
import java.util.Optional;
import java.util.function.BiConsumer;
import java.util.function.Function;

import org.antlr.v4.runtime.CharStreams;
import org.antlr.v4.runtime.Token;
import org.jdbi.v3.core.config.ConfigRegistry;
import org.jdbi.v3.core.internal.lexer.DefineStatementLexer;
import org.jdbi.v3.core.statement.internal.ErrorListener;

import static org.antlr.v4.runtime.Recognizer.EOF;
import static org.jdbi.v3.core.internal.lexer.DefineStatementLexer.COMMENT;
import static org.jdbi.v3.core.internal.lexer.DefineStatementLexer.DEFINE;
import static org.jdbi.v3.core.internal.lexer.DefineStatementLexer.DOUBLE_QUOTED_TEXT;
import static org.jdbi.v3.core.internal.lexer.DefineStatementLexer.ESCAPED_TEXT;
import static org.jdbi.v3.core.internal.lexer.DefineStatementLexer.LITERAL;
import static org.jdbi.v3.core.internal.lexer.DefineStatementLexer.QUOTED_TEXT;

Template engine which replaces angle-bracketed tokens like
<name> with the string value of the named attribute.
Attribute names may contain letters (a-z, A-Z), digits (0-9), or underscores
(_).
/**
 * Template engine which replaces angle-bracketed tokens like
 * <code>&lt;name&gt;</code> with the string value of the named attribute.
 * Attribute names may contain letters (a-z, A-Z), digits (0-9), or underscores
 * (<code>_</code>).
 */
public class DefinedAttributeTemplateEngine implements TemplateEngine.Parsing {
    @Override
    public Optional<Function<StatementContext, String>> parse(String template, ConfigRegistry config) {
        StringBuilder buf = new StringBuilder();
        List<BiConsumer<StatementContext, StringBuilder>> preparation = new ArrayList<>();
        Runnable pushBuf = () -> { // NOPMD
            if (buf.length() > 0) {
                String bit = buf.toString();
                buf.setLength(0);
                preparation.add((ctx, b) -> b.append(bit));
            }
        };
        DefineStatementLexer lexer = new DefineStatementLexer(CharStreams.fromString(template));
        lexer.addErrorListener(new ErrorListener());
        Token t = lexer.nextToken();
        while (t.getType() != EOF) {
            switch (t.getType()) {
            case COMMENT:
            case LITERAL:
            case QUOTED_TEXT:
            case DOUBLE_QUOTED_TEXT:
                buf.append(t.getText());
                break;
            case DEFINE:
                pushBuf.run();
                String text = t.getText();
                String key = text.substring(1, text.length() - 1);
                preparation.add((ctx, b) -> {
                    Object value = ctx.getAttribute(key);
                    if (value == null) {
                        throw new UnableToCreateStatementException("Undefined attribute for token '" + text + "'", ctx);
                    }
                    b.append(value);
                });
                break;
            case ESCAPED_TEXT:
                buf.append(t.getText().substring(1));
                break;
            default:
                break;
            }
            t = lexer.nextToken();
        }
        pushBuf.run();
        return Optional.of(ctx -> {
            try {
                StringBuilder result = new StringBuilder();
                preparation.forEach(a -> a.accept(ctx, result));
                return result.toString();
            } catch (RuntimeException e) {
                throw new UnableToCreateStatementException("Error rendering SQL template: '" + template + "'", e, ctx);
            }
        });
    }
}