Счетчик. Простая модель

Author: Pastor

vol_/src/main/java/ru/mifi/practice/voln/features/CountRange.java

@@ -0,0 +1,92 @@
+package ru.mifi.practice.voln.features;
+
+import lombok.Builder;
+
+import java.time.LocalDateTime;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
+
+public interface CountRange {
+
+    Optional<Long> add(long countId, long userId, long delta);
+
+    Optional<Long> userValue(long countId, long userId);
+
+    Optional<Long> countValue(long countId, long userId);
+
+    final class Default implements CountRange {
+        private static final Value EMPTY = new Value(0, -1, null);
+        private final Map<Long, Count> counts = new HashMap<>();
+        private final Map<Key, Value> values = new HashMap<>();
+
+        private static int indexOf(long[] ranges, long value) {
+            if (value < ranges[0]) {
+                return 0;
+            }
+            for (int i = 1; i < ranges.length; i++) {
+                if (value > ranges[i - 1] && value < ranges[i]) {
+                    return i;
+                }
+            }
+            return ranges.length - 1;
+        }
+
+        @Override
+        public Optional<Long> userValue(long countId, long userId) {
+            return Optional.ofNullable(values.get(new Key(countId, userId))).map(Value::value);
+        }
+
+        @Override
+        public Optional<Long> add(long countId, long userId, long delta) {
+            Count count = this.counts.get(countId);
+            if (count == null) {
+                return Optional.empty();
+            } else if (delta <= 0) {
+                return Optional.empty();
+            }
+            Key key = new Key(countId, userId);
+            Value value = values.computeIfAbsent(key, k -> EMPTY.copy());
+            long[] ranges = count.ranges;
+            int lastIt = indexOf(count.ranges, value.value);
+            int newIt = indexOf(ranges, value.value + delta);
+            value = value.toBuilder().value(value.value + delta).updatedAt(LocalDateTime.now()).build();
+            values.put(key, value);
+            if (lastIt < newIt) {
+                return Optional.of(count.values[newIt]);
+            }
+            return Optional.empty();
+        }
+
+        @Override
+        public Optional<Long> countValue(long countId, long userId) {
+            Count count = this.counts.get(countId);
+            if (count == null) {
+                return Optional.empty();
+            }
+            Key key = new Key(countId, userId);
+            Value value = values.computeIfAbsent(key, k -> EMPTY.copy());
+            int index = indexOf(count.ranges, value.value);
+            return Optional.of(count.values[index]);
+        }
+
+        private record Key(long rangesId, long userId) {
+        }
+    }
+
+
+    @Builder(toBuilder = true)
+    record Value(long value, long accepted, LocalDateTime updatedAt) {
+        private Value copy() {
+            return new Value(value, accepted, updatedAt);
+        }
+    }
+
+    record Count(long id, String name, long[] ranges, long[] values) {
+        public Count {
+            if (ranges.length != values.length) {
+                throw new IllegalArgumentException("Размер диапазонов и размер значений должен совпадать");
+            }
+        }
+    }
+}