implement market overview endpoint

src/main/kotlin/com/frankenergie/smartasset/controller/MarketOverviewController.kt

@@ -0,0 +1,21 @@
+package com.frankenergie.smartasset.controller
+
+import com.frankenergie.smartasset.model.MarketOverviewResponse
+import com.frankenergie.smartasset.model.OrderUpdateRequest
+import com.frankenergie.smartasset.model.OrderUpdateResponse
+import com.frankenergie.smartasset.service.OrderBookService
+import org.springframework.http.ResponseEntity
+import org.springframework.web.bind.annotation.GetMapping
+import org.springframework.web.bind.annotation.RequestBody
+import org.springframework.web.bind.annotation.RequestMapping
+import org.springframework.web.bind.annotation.RestController
+
+@RestController
+@RequestMapping("/api")
+class MarketOverviewController(private val orderBookService: OrderBookService) {
+    @GetMapping("/market/overview")
+    fun getMarketOverview(): ResponseEntity<MarketOverviewResponse> {
+        val response = orderBookService.getMarketOverview()
+        return ResponseEntity.ok(response)
+    }
+}

src/main/kotlin/com/frankenergie/smartasset/model/QuarterOverview.kt

@@ -0,0 +1,12 @@
+package com.frankenergie.smartasset.model
+
+import com.fasterxml.jackson.annotation.JsonProperty
+import java.math.BigDecimal
+import java.time.LocalDateTime
+
+data class QuarterOverview(
+    @JsonProperty("delivery_start_time") val deliveryStartTime: LocalDateTime,
+    @JsonProperty("delivery_end_time") val deliveryEndTime: LocalDateTime,
+    @JsonProperty("highest_buy_price") val highestBuyPrice: BigDecimal?,
+    @JsonProperty("lowest_sell_price") val lowestSellPrice: BigDecimal?
+)

src/main/kotlin/com/frankenergie/smartasset/model/QuarterOverviewResponse.kt

@@ -0,0 +1,9 @@
+package com.frankenergie.smartasset.model
+
+import com.fasterxml.jackson.annotation.JsonProperty
+import java.math.BigDecimal
+import java.time.LocalDateTime
+
+data class MarketOverviewResponse(
+    @JsonProperty("quarters") val quarters: List<QuarterOverview>
+)

src/main/kotlin/com/frankenergie/smartasset/service/OrderBookService.kt

@@ -2,8 +2,10 @@ package com.frankenergie.smartasset.service
 
 import com.frankenergie.smartasset.domain.OrderBook
 import com.frankenergie.smartasset.model.DeliveryPeriod
+import com.frankenergie.smartasset.model.MarketOverviewResponse
 import com.frankenergie.smartasset.model.OrderUpdateRequest
 import com.frankenergie.smartasset.model.OrderUpdateResponse
+import com.frankenergie.smartasset.model.QuarterOverview
 import org.springframework.stereotype.Service
 import java.time.Instant
 import java.util.UUID
@@ -30,5 +32,19 @@ class OrderBookService {
         return OrderUpdateResponse(orderId = orderId, status = status, timestamp = Instant.now())
     }
 
+    fun getMarketOverview(): MarketOverviewResponse {
+        val quarters = orderBook.getAllPeriods()
+            .sortedBy { it.startTime }
+            .map { period ->
+                QuarterOverview(
+                    deliveryStartTime = period.startTime,
+                    deliveryEndTime = period.endTime,
+                    highestBuyPrice = orderBook.getBestBid(period)?.price,
+                    lowestSellPrice = orderBook.getBestAsk(period)?.price
+                )
+            }
+        return MarketOverviewResponse(quarters)
+    }
+
     fun getOrderBook(): OrderBook = orderBook
 }