QuerySpecBuilder.java

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package dev.rafex.ether.http.core.query;
 
/*-
 * #%L
 * ether-http-core
 * %%
 * Copyright (C) 2025 - 2026 Raúl Eduardo González Argote
 * %%
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 * #L%
 */
 
import java.util.ArrayList;
import java.util.List;
 
public final class QuerySpecBuilder {
 
    private static final int MIN_LIMIT = 1;
    private static final int MAX_LIMIT = 200;
    private static final int MIN_OFFSET = 0;
    private static final int MAX_OFFSET = 100_000;
 
    private final RsqlParser parser = new RsqlParser();
 
    public QuerySpec fromRawParams(final String q, final String tags, final String locationId, final String enabled,
            final String sort, final String limit, final String offset) {
 
        final RsqlNode rsqlFilter = parser.parse(trimToNull(q));
        final RsqlNode queryFilter = buildClassicFilter(tags, locationId, enabled);
        final RsqlNode finalFilter = mergeWithAnd(rsqlFilter, queryFilter);
 
        final int finalLimit = parseIntClamp(limit, QuerySpec.DEFAULT_LIMIT, MIN_LIMIT, MAX_LIMIT, "limit");
        final int finalOffset = parseIntClamp(offset, QuerySpec.DEFAULT_OFFSET, MIN_OFFSET, MAX_OFFSET, "offset");
        final var sorts = parseSort(sort);
 
        return new QuerySpec(finalFilter, finalLimit, finalOffset, sorts);
    }
 
    private RsqlNode buildClassicFilter(final String tagsRaw, final String locationIdRaw, final String enabledRaw) {
        final var filters = new ArrayList<RsqlNode>();
 
        final var tags = parseCsv(tagsRaw);
        if (!tags.isEmpty()) {
            filters.add(new RsqlNode.Comp("tags", RsqlOperator.IN, tags));
        }
 
        final var locationId = trimToNull(locationIdRaw);
        if (locationId != null) {
            filters.add(new RsqlNode.Comp("locationId", RsqlOperator.EQ, List.of(locationId)));
        }
 
        final var enabled = trimToNull(enabledRaw);
        if (enabled != null) {
            final String normalized;
            if ("true".equalsIgnoreCase(enabled) || "false".equalsIgnoreCase(enabled)) {
                normalized = enabled.toLowerCase();
            } else {
                throw new IllegalArgumentException("enabled must be true or false");
            }
            filters.add(new RsqlNode.Comp("enabled", RsqlOperator.EQ, List.of(normalized)));
        }
 
        if (filters.isEmpty()) {
            return null;
        }
        return filters.size() == 1 ? filters.get(0) : new RsqlNode.And(filters);
    }
 
    private List<Sort> parseSort(final String sortRaw) {
        final var sort = trimToNull(sortRaw);
        if (sort == null) {
            return List.of();
        }
 
        final var out = new ArrayList<Sort>();
        for (final String tokenRaw : sort.split(",")) {
            final var token = tokenRaw.trim();
            if (token.isEmpty()) {
                continue;
            }
            if (token.startsWith("-")) {
                if (token.length() == 1) {
                    throw new IllegalArgumentException("invalid sort field");
                }
                out.add(new Sort(token.substring(1), Sort.Direction.DESC));
            } else {
                out.add(new Sort(token, Sort.Direction.ASC));
            }
        }
        return out;
    }
 
    private static List<String> parseCsv(final String raw) {
        final var value = trimToNull(raw);
        if (value == null) {
            return List.of();
        }
        final var out = new ArrayList<String>();
        for (final String tokenRaw : value.split(",")) {
            final var token = tokenRaw.trim();
            if (!token.isEmpty()) {
                out.add(token);
            }
        }
        return out;
    }
 
    private static int parseIntClamp(final String valueRaw, final int defaultValue, final int min, final int max,
            final String fieldName) {
        final var value = trimToNull(valueRaw);
        if (value == null) {
            return defaultValue;
        }
        try {
            final var parsed = Integer.parseInt(value);
            if (parsed < min) {
                return min;
            }
            if (parsed > max) {
                return max;
            }
            return parsed;
        } catch (final NumberFormatException e) {
            throw new IllegalArgumentException(fieldName + " must be an integer");
        }
    }
 
    private static RsqlNode mergeWithAnd(final RsqlNode left, final RsqlNode right) {
        if (left == null) {
            return right;
        }
        if (right == null) {
            return left;
        }
        return new RsqlNode.And(List.of(left, right));
    }
 
    private static String trimToNull(final String value) {
        if (value == null) {
            return null;
        }
        final var trimmed = value.trim();
        return trimmed.isEmpty() ? null : trimmed;
    }
}