[OPIK-397] Add trace stats endpoint

apps/opik-backend/src/main/java/com/comet/opik/api/ProjectStats.java

@@ -0,0 +1,105 @@
+package com.comet.opik.api;
+
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import com.fasterxml.jackson.annotation.JsonSubTypes;
+import com.fasterxml.jackson.annotation.JsonTypeInfo;
+import com.fasterxml.jackson.databind.PropertyNamingStrategies;
+import com.fasterxml.jackson.databind.annotation.JsonNaming;
+import io.swagger.v3.oas.annotations.media.DiscriminatorMapping;
+import io.swagger.v3.oas.annotations.media.Schema;
+import lombok.Builder;
+import lombok.EqualsAndHashCode;
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+import lombok.ToString;
+import lombok.experimental.SuperBuilder;
+
+import java.beans.ConstructorProperties;
+import java.math.BigDecimal;
+import java.util.List;
+
+@Builder(toBuilder = true)
+@JsonIgnoreProperties(ignoreUnknown = true)
+@JsonNaming(PropertyNamingStrategies.SnakeCaseStrategy.class)
+public record ProjectStats(List<ProjectStatItem<?>> stats) {
+
+    public static ProjectStats empty() {
+        return new ProjectStats(List.of());
+    }
+
+    @JsonIgnoreProperties(ignoreUnknown = true)
+    @JsonNaming(PropertyNamingStrategies.SnakeCaseStrategy.class)
+    @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.EXISTING_PROPERTY, property = "type", visible = true)
+    @JsonSubTypes({
+            @JsonSubTypes.Type(value = PercentageValueStat.class, name = "PERCENTAGE"),
+            @JsonSubTypes.Type(value = CountValueStat.class, name = "COUNT"),
+            @JsonSubTypes.Type(value = AvgValueStat.class, name = "AVG")
+    })
+    @Schema(discriminatorProperty = "type", discriminatorMapping = {
+            @DiscriminatorMapping(value = "PERCENTAGE", schema = PercentageValueStat.class),
+            @DiscriminatorMapping(value = "COUNT", schema = CountValueStat.class),
+            @DiscriminatorMapping(value = "AVG", schema = AvgValueStat.class),
+    })
+    @RequiredArgsConstructor
+    @Getter
+    @SuperBuilder(toBuilder = true)
+    @EqualsAndHashCode
+    @ToString(callSuper = true)
+    public abstract static sealed class ProjectStatItem<T> {
+        private final String name;
+        private final T value;
+        private final StatsType type;
+    }
+
+    @ToString(callSuper = true)
+    @EqualsAndHashCode(callSuper = true)
+    @SuperBuilder(toBuilder = true)
+    @Getter
+    public abstract static sealed class SingleValueStat<T extends Number> extends ProjectStatItem<T> {
+    }
+
+    @ToString(callSuper = true)
+    @EqualsAndHashCode(callSuper = true)
+    @SuperBuilder(toBuilder = true)
+    @Getter
+    public static final class CountValueStat extends SingleValueStat<Long> {
+
+        @ConstructorProperties({"name", "value"})
+        public CountValueStat(String name, Long value) {
+            super(CountValueStat.builder().value(value).name(name).type(StatsType.COUNT));
+        }
+    }
+
+    @ToString(callSuper = true)
+    @EqualsAndHashCode(callSuper = true)
+    @SuperBuilder(toBuilder = true)
+    @Getter
+    public static final class AvgValueStat extends SingleValueStat<Number> {
+
+        @ConstructorProperties({"name", "value"})
+        public AvgValueStat(String name, Number value) {
+            super(AvgValueStat.builder().value(value).name(name).type(StatsType.AVG));
+        }
+    }
+
+    public record PercentageValues(double p50, double p90, double p99) {
+    }
+
+    @ToString(callSuper = true)
+    @EqualsAndHashCode(callSuper = true)
+    @SuperBuilder(toBuilder = true)
+    @Getter
+    public static final class PercentageValueStat extends ProjectStatItem<PercentageValues> {
+
+        @ConstructorProperties({"name", "value"})
+        public PercentageValueStat(String name, PercentageValues value) {
+            super(PercentageValueStat.builder().value(value).name(name).type(StatsType.PERCENTAGE));
+        }
+    }
+
+    public enum StatsType {
+        COUNT,
+        PERCENTAGE,
+        AVG
+    }
+}

apps/opik-backend/src/main/java/com/comet/opik/api/resources/v1/priv/TracesResource.java

@@ -6,6 +6,7 @@
 import com.comet.opik.api.FeedbackScore;
 import com.comet.opik.api.FeedbackScoreBatch;
 import com.comet.opik.api.FeedbackScoreNames;
+import com.comet.opik.api.ProjectStats;
 import com.comet.opik.api.Trace;
 import com.comet.opik.api.Trace.TracePage;
 import com.comet.opik.api.TraceBatch;
@@ -294,6 +295,37 @@ public Response scoreBatchOfTraces(
         return Response.noContent().build();
     }
 
+    @GET
+    @Path("/stats")
+    @Operation(operationId = "getTraceStats", summary = "Get trace stats", description = "Get trace stats", responses = {
+            @ApiResponse(responseCode = "200", description = "Trace stats resource", content = @Content(schema = @Schema(implementation = ProjectStats.class)))
+    })
+    public Response getStats(@QueryParam("project_id") UUID projectId,
+            @QueryParam("project_name") String projectName,
+            @QueryParam("filters") String filters) {
+
+        validateProjectNameAndProjectId(projectName, projectId);
+        var traceFilters = filtersFactory.newFilters(filters, TraceFilter.LIST_TYPE_REFERENCE);
+        var searchCriteria = TraceSearchCriteria.builder()
+                .projectName(projectName)
+                .projectId(projectId)
+                .filters(traceFilters)
+                .build();
+
+        String workspaceId = requestContext.get().getWorkspaceId();
+
+        log.info("Get trace stats by '{}' on workspaceId '{}'", searchCriteria, workspaceId);
+
+        ProjectStats projectStats = service.getStats(searchCriteria)
+                .contextWrite(ctx -> setRequestContext(ctx, requestContext))
+                .block();
+
+        log.info("Found trace stats by '{}', count '{}' on workspaceId '{}'", searchCriteria,
+                projectStats.stats().size(), workspaceId);
+
+        return Response.ok(projectStats).build();
+    }
+
     @GET
     @Path("/feedback-scores/names")
     @Operation(operationId = "findFeedbackScoreNames", summary = "Find Feedback Score names", description = "Find Feedback Score names", responses = {