prepare the addition of a date index

data-store/src/main/java/org/lucares/pdb/datastore/DateTimeRange.java

@@ -0,0 +1,29 @@
+package org.lucares.pdb.datastore;
+
+import java.time.OffsetDateTime;
+
+public class DateTimeRange {
+
+	public static final DateTimeRange MAX = new DateTimeRange(OffsetDateTime.MIN, OffsetDateTime.MAX);
+
+	private final OffsetDateTime start;
+	private final OffsetDateTime end;
+
+	public DateTimeRange(final OffsetDateTime start, final OffsetDateTime end) {
+		this.start = start;
+		this.end = end;
+	}
+
+	public OffsetDateTime getStart() {
+		return start;
+	}
+
+	public OffsetDateTime getEnd() {
+		return end;
+	}
+
+	@Override
+	public String toString() {
+		return start + "-" + end;
+	}
+}

data-store/src/main/java/org/lucares/pdb/datastore/lang/DateIndexExtension.java

@@ -0,0 +1,109 @@
+package org.lucares.pdb.datastore.lang;
+
+import java.time.Instant;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
+import java.time.format.DateTimeFormatter;
+import java.util.Map.Entry;
+import java.util.Objects;
+import java.util.Set;
+import java.util.TreeSet;
+import java.util.concurrent.ConcurrentNavigableMap;
+import java.util.concurrent.ConcurrentSkipListMap;
+
+import org.lucares.pdb.datastore.DateTimeRange;
+
+public class DateIndexExtension {
+
+	/**
+	 * This date pattern defines the resolution of the date index
+	 */
+	private static final DateTimeFormatter DATE_PATTERN = DateTimeFormatter.ofPattern("yyyyMM");
+
+	// visible for test
+	static final ConcurrentNavigableMap<Long, DatePrefixAndRange> DATE_PREFIX_CACHE = new ConcurrentSkipListMap<>();
+
+	static Set<String> toDateIndexPrefix(final DateTimeRange dateRange) {
+		final Set<String> result = new TreeSet<>();
+		if (Objects.equals(dateRange, DateTimeRange.MAX)) {
+			result.add("*");
+		} else {
+			OffsetDateTime current = dateRange.getStart();
+			while (current.isBefore(dateRange.getEnd())) {
+
+				result.add(toDateIndexPrefix(current));
+				current = current.plusMonths(1);
+
+			}
+			result.add(toDateIndexPrefix(dateRange.getEnd()));
+		}
+		return result;
+	}
+
+	static String toDateIndexPrefix(final OffsetDateTime time) {
+		return time.format(DATE_PATTERN);
+	}
+
+	public static String toDateIndexPrefix(final long epochMilli) {
+
+		final Entry<Long, DatePrefixAndRange> value = DATE_PREFIX_CACHE.floorEntry(epochMilli);
+
+		String result;
+		if (value == null || !value.getValue().contains(epochMilli)) {
+			final DatePrefixAndRange newValue = toDatePrefixAndRange(epochMilli);
+			DATE_PREFIX_CACHE.put(newValue.getMinEpochMilli(), newValue);
+			result = newValue.getDatePrefix();
+		} else {
+			result = value.getValue().getDatePrefix();
+		}
+
+		return result;
+	}
+
+	private static DatePrefixAndRange toDatePrefixAndRange(final long epochMilli) {
+		final OffsetDateTime date = Instant.ofEpochMilli(epochMilli).atOffset(ZoneOffset.UTC);
+		final OffsetDateTime beginOfMonth = date.withDayOfMonth(1).withHour(0).withMinute(0).withSecond(0).withNano(0);
+		final OffsetDateTime endOfMonth = beginOfMonth.plusMonths(1).minusNanos(1);
+
+		final String datePrefix = date.format(DATE_PATTERN);
+		final long minEpochMilli = beginOfMonth.toInstant().toEpochMilli();
+		final long maxEpochMilli = endOfMonth.toInstant().toEpochMilli();
+
+		return new DatePrefixAndRange(datePrefix, minEpochMilli, maxEpochMilli);
+	}
+
+}
+
+class DatePrefixAndRange {
+	private final String datePrefix;
+	private final long minEpochMilli;
+	private final long maxEpochMilli;
+
+	public DatePrefixAndRange(final String datePrefix, final long minEpochMilli, final long maxEpochMilli) {
+		super();
+		this.datePrefix = datePrefix;
+		this.minEpochMilli = minEpochMilli;
+		this.maxEpochMilli = maxEpochMilli;
+	}
+
+	public String getDatePrefix() {
+		return datePrefix;
+	}
+
+	public long getMinEpochMilli() {
+		return minEpochMilli;
+	}
+
+	public long getMaxEpochMilli() {
+		return maxEpochMilli;
+	}
+
+	public boolean contains(final long epochMilli) {
+		return minEpochMilli <= epochMilli && epochMilli <= maxEpochMilli;
+	}
+
+	@Override
+	public String toString() {
+		return datePrefix + " (" + minEpochMilli + " - " + maxEpochMilli + ")";
+	}
+}

data-store/src/main/java/org/lucares/pdb/datastore/lang/Expression.java

@@ -1,6 +1,7 @@
 package org.lucares.pdb.datastore.lang;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 
 import org.lucares.utils.CollectionUtils;
@@ -190,6 +191,19 @@ abstract public class Expression {
 			return true;
 		}
 
+		public static Expression create(final List<Expression> or) {
+
+			if (or.size() == 1) {
+				return or.get(0);
+			} else {
+				Or result = new Or(or.get(0), or.get(1));
+				for (int i = 2; i < or.size(); i++) {
+					result = new Or(result, or.get(i));
+				}
+				return result;
+			}
+		}
+
 	}
 
 	static class And extends Expression {
@@ -465,6 +479,10 @@ abstract public class Expression {
 		private final String property;
 		private final List<String> values;
 
+		public InExpression(final String property, final String value) {
+			this(property, Arrays.asList(value));
+		}
+
 		public InExpression(final String property, final List<String> values) {
 			this.property = property;
 			this.values = values;

data-store/src/main/java/org/lucares/pdb/datastore/lang/ExpressionToDocIdVisitor.java

@@ -49,7 +49,6 @@ public class ExpressionToDocIdVisitor extends ExpressionVisitor<IntList> {
 	}
 
 	private static final Map<String, IntList> EMPTY_VALUES = Collections.emptyMap();
-	private static final IntList EMPTY_DOC_IDS = new IntList();
 	private final Map<String, Map<String, IntList>> keyToValueToDocId;
 	private final AllDocIds allDocIds;