feat: Multiple historical fees

app/src/main/kotlin/xyz/block/augurref/api/HistoricalFeeEndpoint.kt

@@ -76,4 +76,61 @@ fun Route.configureHistoricalFeesEndpoint(mempoolCollector: MempoolCollector) {
       call.respond(response)
     }
   }
+
+  get("/historical_fees") {
+    logger.info("Received request for historical fee estimates")
+
+    // Extract params from query start_timestamp, end_timestamp, interval (seconds)
+    val startTimestampParam = call.request.queryParameters["start_timestamp"]?.toLongOrNull()
+    val endTimestampParam = call.request.queryParameters["end_timestamp"]?.toLongOrNull()
+    val intervalParam = call.request.queryParameters["interval"]
+    val interval: Int = intervalParam?.toIntOrNull() ?: 3600
+
+    if (startTimestampParam == null) {
+      call.respondText(
+        "start_timestamp parameter is required",
+        status = HttpStatusCode.BadRequest,
+        contentType = ContentType.Text.Plain,
+      )
+      return@get
+    }
+
+    if (endTimestampParam == null) {
+      call.respondText(
+        "end_timestamp parameter is required",
+        status = HttpStatusCode.BadRequest,
+        contentType = ContentType.Text.Plain,
+      )
+      return@get
+    }
+
+    // Fetch historical fee estimate based on date
+    logger.info(
+      "Fetching historical fee estimate for start_timestamp: $startTimestampParam to " +
+        "end_timestamp: $endTimestampParam for intervals: $interval seconds",
+    )
+    val feeEstimate = mempoolCollector.getFeeEstimateForTimestampRange(startTimestampParam, endTimestampParam, interval)
+
+    if (feeEstimate == null) {
+      logger.warn(
+        "No historical fee estimates available for start_timestamp $startTimestampParam to " +
+          "end_timestamp: $endTimestampParam for interval: $interval seconds",
+      )
+      call.respondText(
+        "No historical fee estimates available for start_timestamp $startTimestampParam to " +
+          "end_timestamp: $endTimestampParam for interval: $interval seconds",
+        status = HttpStatusCode.ServiceUnavailable,
+        contentType = ContentType.Text.Plain,
+      )
+    } else {
+      var mutableResponse = mutableListOf<FeeEstimateResponse>()
+      logger.info("Transforming historical fee estimates for response")
+      for (estimate in feeEstimate) {
+        val response = transformFeeEstimate(estimate)
+        mutableResponse.add(response)
+      }
+      logger.debug("Returning historical fee estimates")
+      call.respond(mutableResponse)
+    }
+  }
 }

app/src/main/kotlin/xyz/block/augurref/service/MempoolCollector.kt

@@ -72,6 +72,42 @@ class MempoolCollector(
     return latestFeeEstimate.get()
   }
 
+  fun getFeeEstimateForTimestampRange(start_date: Long, end_date: Long, interval: Int): List<FeeEstimate>? {
+    // Ensure start_date is not after end_date
+    if (start_date > end_date) {
+      logger.warn("Start date is after end date")
+      return null
+    }
+
+    // Initialize result list to store fee estimates
+    val estimates = mutableListOf<FeeEstimate>()
+    var currentDate = start_date
+
+    // Iterate through the date range with the given interval
+    while (currentDate < end_date) {
+      logger.debug("Processing fee estimate for $currentDate")
+      val feeEstimate = getFeeEstimateForTimestamp(currentDate)
+
+      // If fee estimate is non-null and has estimates, merge them
+      if (feeEstimate != null && feeEstimate.estimates.isNotEmpty()) {
+        estimates.add(feeEstimate)
+      } else {
+        logger.debug("No valid fee estimate for $currentDate")
+      }
+
+      currentDate = currentDate + interval
+    }
+
+    // Return null if no estimates were collected
+    if (estimates.isEmpty()) {
+      logger.warn("No fee estimates collected for the date range")
+      return null
+    }
+
+    // Return a FeeEstimate with the aggregated estimates
+    return estimates
+  }
+
   /**
    * Get the fee estimate for specific date
    */

app/src/test/kotlin/xyz/block/augurref/api/FeeEstimateEndpointTest.kt

@@ -205,7 +205,6 @@ class FeeEstimateEndpointTest {
     verify { mockMempoolCollector.getLatestFeeEstimateForBlockTarget(2.0) }
   }
 
-
   private fun createMockFeeEstimate(timestamp: Instant): FeeEstimate {
     // Create mock data using the actual augur library structure
     val mockFeeEstimate = mockk<FeeEstimate>()