Hide last link when needed, add first link (#532)

* No lastLink on last page

* Lint

* Copilot

* Out of offset

* Add firstLink

Author: jakub-id

broker/api/common.go

@@ -57,22 +57,35 @@ func CollectAboutData(fullCount int64, offset int32, limit int32, r *http.Reques
 	}
 	limit64 := int64(limit)
 	offset64 := int64(offset)
+	lastOffset := int64(0)
+	if fullCount > 0 {
+		lastOffset = ((fullCount - 1) / limit64) * limit64
+	}
 	if fullCount > limit64 {
-		lastOffset := ((fullCount - 1) / limit64) * limit64
-		urlValues := r.URL.Query()
-		urlValues["offset"] = []string{strconv.FormatInt(lastOffset, 10)}
-		link := ToLinkUrlValues(r, urlValues)
-		about.LastLink = &link
+		if offset64 != lastOffset {
+			urlValues := r.URL.Query()
+			urlValues["offset"] = []string{strconv.FormatInt(lastOffset, 10)}
+			link := ToLinkUrlValues(r, urlValues)
+			about.LastLink = &link
+		}
 	}
 	if offset64 > 0 {
+		urlValues := r.URL.Query()
+		urlValues["offset"] = []string{"0"}
+		firstLink := ToLinkUrlValues(r, urlValues)
+		about.FirstLink = &firstLink
+
 		pOffset := offset64 - limit64
 		if pOffset < 0 {
 			pOffset = 0
 		}
-		urlValues := r.URL.Query()
+		if pOffset > lastOffset {
+			pOffset = lastOffset
+		}
+		urlValues = r.URL.Query()
 		urlValues["offset"] = []string{strconv.FormatInt(pOffset, 10)}
-		link := ToLinkUrlValues(r, urlValues)
-		about.PrevLink = &link
+		prevLink := ToLinkUrlValues(r, urlValues)
+		about.PrevLink = &prevLink
 	}
 	if fullCount > offset64+limit64 {
 		noffset := offset64 + limit64

broker/api/common_test.go

@@ -2,6 +2,7 @@ package api
 
 import (
 	"net/http"
+	"net/http/httptest"
 	"strings"
 	"testing"
 
@@ -25,3 +26,76 @@ func TestGetSymbolForRequest(t *testing.T) {
 	assert.Equal(t, "tenant mapping must be specified", err.Error())
 	assert.Equal(t, "", resolved)
 }
+
+func TestCollectAboutDataLastLink(t *testing.T) {
+	reqOffset0 := httptest.NewRequest("GET", "http://localhost/ill_transactions?symbol=ISIL:DK-BIB1&offset=0", nil)
+	reqOffset10 := httptest.NewRequest("GET", "http://localhost/ill_transactions?symbol=ISIL:DK-BIB1&offset=10", nil)
+	reqOffset20 := httptest.NewRequest("GET", "http://localhost/ill_transactions?symbol=ISIL:DK-BIB1&offset=20", nil)
+	reqOffset1000 := httptest.NewRequest("GET", "http://localhost/ill_transactions?symbol=ISIL:DK-BIB1&offset=1000", nil)
+
+	// First page (count=21, limit=10, offset=0): prevLink omitted, next/last present.
+	about := CollectAboutData(21, 0, 10, reqOffset0)
+	assert.Equal(t, int64(21), about.Count)
+	assert.Nil(t, about.FirstLink)
+	assert.Nil(t, about.PrevLink)
+	assert.NotNil(t, about.NextLink)
+	assert.Contains(t, *about.NextLink, "offset=10")
+	assert.Contains(t, *about.NextLink, "symbol=ISIL%3ADK-BIB1")
+	assert.NotNil(t, about.LastLink)
+	assert.Contains(t, *about.LastLink, "offset=20")
+	assert.Contains(t, *about.LastLink, "symbol=ISIL%3ADK-BIB1")
+
+	// Not last page (count=21, limit=10, offset=10): all links present
+	about = CollectAboutData(21, 10, 10, reqOffset10)
+	assert.Equal(t, int64(21), about.Count)
+	assert.NotNil(t, about.FirstLink)
+	assert.Contains(t, *about.FirstLink, "offset=0")
+	assert.Contains(t, *about.FirstLink, "symbol=ISIL%3ADK-BIB1")
+	assert.NotNil(t, about.PrevLink)
+	assert.Contains(t, *about.PrevLink, "offset=0")
+	assert.Contains(t, *about.PrevLink, "symbol=ISIL%3ADK-BIB1")
+	assert.NotNil(t, about.NextLink)
+	assert.Contains(t, *about.NextLink, "offset=20")
+	assert.Contains(t, *about.NextLink, "symbol=ISIL%3ADK-BIB1")
+	assert.NotNil(t, about.LastLink)
+	assert.Contains(t, *about.LastLink, "offset=20")
+	assert.Contains(t, *about.LastLink, "symbol=ISIL%3ADK-BIB1")
+
+	// Last page (count=20, limit=10, offset=10): lastLink and nextLink should be omitted.
+	about = CollectAboutData(20, 10, 10, reqOffset10)
+	assert.Equal(t, int64(20), about.Count)
+	assert.NotNil(t, about.FirstLink)
+	assert.Contains(t, *about.FirstLink, "offset=0")
+	assert.Contains(t, *about.FirstLink, "symbol=ISIL%3ADK-BIB1")
+	assert.NotNil(t, about.PrevLink)
+	assert.Contains(t, *about.PrevLink, "offset=0")
+	assert.Contains(t, *about.PrevLink, "symbol=ISIL%3ADK-BIB1")
+	assert.Nil(t, about.NextLink)
+	assert.Nil(t, about.LastLink)
+
+	// Last partial page (count=21, limit=10, offset=20): lastLink and nextLink should be omitted.
+	about = CollectAboutData(21, 20, 10, reqOffset20)
+	assert.Equal(t, int64(21), about.Count)
+	assert.NotNil(t, about.FirstLink)
+	assert.Contains(t, *about.FirstLink, "offset=0")
+	assert.Contains(t, *about.FirstLink, "symbol=ISIL%3ADK-BIB1")
+	assert.NotNil(t, about.PrevLink)
+	assert.Contains(t, *about.PrevLink, "offset=10")
+	assert.Contains(t, *about.PrevLink, "symbol=ISIL%3ADK-BIB1")
+	assert.Nil(t, about.NextLink)
+	assert.Nil(t, about.LastLink)
+
+	// Out-of-range page (count=21, limit=10, offset=1000): prevLink and lastLink should be present.
+	about = CollectAboutData(21, 1000, 10, reqOffset1000)
+	assert.Equal(t, int64(21), about.Count)
+	assert.NotNil(t, about.FirstLink)
+	assert.Contains(t, *about.FirstLink, "offset=0")
+	assert.Contains(t, *about.FirstLink, "symbol=ISIL%3ADK-BIB1")
+	assert.NotNil(t, about.PrevLink)
+	assert.Contains(t, *about.PrevLink, "offset=20")
+	assert.Contains(t, *about.PrevLink, "symbol=ISIL%3ADK-BIB1")
+	assert.Nil(t, about.NextLink)
+	assert.NotNil(t, about.LastLink)
+	assert.Contains(t, *about.LastLink, "offset=20")
+	assert.Contains(t, *about.LastLink, "symbol=ISIL%3ADK-BIB1")
+}

broker/oapi/open-api.yaml

@@ -212,6 +212,9 @@ components:
         prevLink:
           type: string
           description: Link to the previous page of results
+        firstLink:
+          type: string
+          description: Link to the first page of results
         lastLink:
           type: string
           description: Link to the last page of results