refactor: change alert parts calculations

senders/calc_message_parts.go

@@ -14,3 +14,70 @@ func CalculateMessagePartsLength(maxChars, descLen, eventsLen int) (descNewLen i
 	}
 	return maxChars/2 - 10, maxChars / 2
 }
+
+const (
+	// messagePartsCount is the number of parts in alert, which will be recalculated.
+	messagePartsCount = 3
+)
+
+// CalculateMessagePartsBetweenTagsDescEvents calculates and returns the length of tags, description and events string
+// in order to fit the max chars limit.
+func CalculateMessagePartsBetweenTagsDescEvents(maxChars, tagsLen, descLen, eventsLen int) (tagsNewLen int, descNewLen int, eventsNewLen int) { // nolint
+	if maxChars <= 0 {
+		return 0, 0, 0
+	}
+
+	if tagsLen+descLen+eventsLen <= maxChars {
+		return tagsLen, descLen, eventsLen
+	}
+
+	fairMaxLen := maxChars / messagePartsCount
+
+	switch {
+	case firstIsGreaterThanGivenLenAndOthersLessOrEqual(fairMaxLen, tagsLen, descLen, eventsLen):
+		// give free space to tags
+		tagsNewLen = maxChars - descLen - eventsLen
+
+		return min(tagsNewLen, tagsLen), descLen, eventsLen
+	case firstIsGreaterThanGivenLenAndOthersLessOrEqual(fairMaxLen, descLen, tagsLen, eventsLen):
+		// give free space to description
+		descNewLen = maxChars - tagsLen - eventsLen
+
+		return tagsLen, min(descNewLen, descLen), eventsLen
+	case firstIsGreaterThanGivenLenAndOthersLessOrEqual(fairMaxLen, eventsLen, tagsLen, descLen):
+		// give free space to events
+		eventsNewLen = maxChars - tagsLen - descLen
+
+		return tagsLen, descLen, min(eventsNewLen, eventsLen)
+	case firstAndSecondIsGreaterThanGivenLenAndOtherLessOrEqual(fairMaxLen, tagsLen, descLen, eventsLen):
+		// description is more important than tags
+		tagsNewLen = fairMaxLen
+		descNewLen = maxChars - tagsNewLen - eventsLen
+
+		return tagsNewLen, min(descNewLen, descLen), eventsLen
+	case firstAndSecondIsGreaterThanGivenLenAndOtherLessOrEqual(fairMaxLen, tagsLen, eventsLen, descLen):
+		// events are more important than tags
+		tagsNewLen = fairMaxLen
+		eventsNewLen = maxChars - tagsNewLen - descLen
+
+		return tagsNewLen, descLen, min(eventsNewLen, eventsLen)
+	case firstAndSecondIsGreaterThanGivenLenAndOtherLessOrEqual(fairMaxLen, descLen, eventsLen, tagsLen):
+		// split free space from tags fairly between description and events
+		spaceFromTags := fairMaxLen - tagsLen
+		descNewLen = fairMaxLen + spaceFromTags/2
+		eventsNewLen = fairMaxLen + spaceFromTags/2
+
+		return tagsLen, min(descNewLen, descLen), min(eventsNewLen, eventsLen)
+	default:
+		// all 3 blocks have length greater than maxChars/3, so split space fairly
+		return fairMaxLen, fairMaxLen, fairMaxLen
+	}
+}
+
+func firstIsGreaterThanGivenLenAndOthersLessOrEqual(givenLen, first, second, third int) bool {
+	return first > givenLen && second <= givenLen && third <= givenLen
+}
+
+func firstAndSecondIsGreaterThanGivenLenAndOtherLessOrEqual(givenLen, first, second, third int) bool {
+	return first > givenLen && second > givenLen && third <= givenLen
+}

senders/calc_message_parts_test.go

@@ -1,6 +1,7 @@
 package senders
 
 import (
+	"fmt"
 	"testing"
 
 	. "github.com/smartystreets/goconvey/convey"
@@ -33,3 +34,179 @@ func TestCalculateMessagePartsLength(t *testing.T) {
 		})
 	})
 }
+
+func TestCalculateMessagePartsBetweenTagsDescEvents(t *testing.T) {
+	Convey("Message parts calculating test (for tags, desc, events)", t, func() {
+		type given struct {
+			maxChars  int
+			tagsLen   int
+			descLen   int
+			eventsLen int
+		}
+
+		type expected struct {
+			tagsLen   int
+			descLen   int
+			eventsLen int
+		}
+
+		type testcase struct {
+			given       given
+			expected    expected
+			description string
+		}
+
+		cases := []testcase{
+			{
+				description: "with maxChars < 0",
+				given: given{
+					maxChars:  -1,
+					tagsLen:   10,
+					descLen:   10,
+					eventsLen: 10,
+				},
+				expected: expected{
+					tagsLen:   0,
+					descLen:   0,
+					eventsLen: 0,
+				},
+			},
+			{
+				description: "with tagsLen + descLen + eventsLen <= maxChars",
+				given: given{
+					maxChars:  100,
+					tagsLen:   20,
+					descLen:   50,
+					eventsLen: 30,
+				},
+				expected: expected{
+					tagsLen:   20,
+					descLen:   50,
+					eventsLen: 30,
+				},
+			},
+			{
+				description: "with tagsLen > maxChars/3, descLen and eventsLen <= maxChars/3",
+				given: given{
+					maxChars:  100,
+					tagsLen:   50,
+					descLen:   30,
+					eventsLen: 30,
+				},
+				expected: expected{
+					tagsLen:   40,
+					descLen:   30,
+					eventsLen: 30,
+				},
+			},
+			{
+				description: "with descLen > maxChars/3, tagsLen and eventsLen <= maxChars/3",
+				given: given{
+					maxChars:  100,
+					tagsLen:   30,
+					descLen:   50,
+					eventsLen: 31,
+				},
+				expected: expected{
+					tagsLen:   30,
+					descLen:   39,
+					eventsLen: 31,
+				},
+			},
+			{
+				description: "with eventsLen > maxChars/3, tagsLen and descLen <= maxChars/3",
+				given: given{
+					maxChars:  100,
+					tagsLen:   33,
+					descLen:   33,
+					eventsLen: 61,
+				},
+				expected: expected{
+					tagsLen:   33,
+					descLen:   33,
+					eventsLen: 34,
+				},
+			},
+			{
+				description: "with tagsLen and descLen > maxChars/3, eventsLen <= maxChars/3",
+				given: given{
+					maxChars:  100,
+					tagsLen:   55,
+					descLen:   46,
+					eventsLen: 31,
+				},
+				expected: expected{
+					tagsLen:   33,
+					descLen:   36,
+					eventsLen: 31,
+				},
+			},
+			{
+				description: "with tagsLen and eventsLen > maxChars/3, descLen <= maxChars/3",
+				given: given{
+					maxChars:  100,
+					tagsLen:   55,
+					descLen:   33,
+					eventsLen: 100,
+				},
+				expected: expected{
+					tagsLen:   33,
+					descLen:   33,
+					eventsLen: 34,
+				},
+			},
+			{
+				description: "with descLen and eventsLen > maxChars/3, tagsLen <= maxChars/3",
+				given: given{
+					maxChars:  100,
+					tagsLen:   55,
+					descLen:   33,
+					eventsLen: 100,
+				},
+				expected: expected{
+					tagsLen:   33,
+					descLen:   33,
+					eventsLen: 34,
+				},
+			},
+			{
+				description: "with tagsLen, descLen and eventsLen > maxChars/3",
+				given: given{
+					maxChars:  100,
+					tagsLen:   55,
+					descLen:   40,
+					eventsLen: 100,
+				},
+				expected: expected{
+					tagsLen:   33,
+					descLen:   33,
+					eventsLen: 33,
+				},
+			},
+			{
+				description: "with tagsLen, descLen > maxChars/3, eventsLen <= maxChars/3 and maxChars - maxChars/3 - eventsLen > descLen",
+				given: given{
+					maxChars:  100,
+					tagsLen:   100,
+					descLen:   34,
+					eventsLen: 20,
+				},
+				expected: expected{
+					tagsLen:   33,
+					descLen:   34,
+					eventsLen: 20,
+				},
+			},
+		}
+
+		for i, c := range cases {
+			Convey(fmt.Sprintf("case %d: %s", i+1, c.description), func() {
+				tagsNewLen, descNewLen, eventsNewLen := CalculateMessagePartsBetweenTagsDescEvents(c.given.maxChars, c.given.tagsLen, c.given.descLen, c.given.eventsLen)
+
+				So(tagsNewLen, ShouldResemble, c.expected.tagsLen)
+				So(descNewLen, ShouldResemble, c.expected.descLen)
+				So(eventsNewLen, ShouldResemble, c.expected.eventsLen)
+			})
+		}
+	})
+}

senders/msgformat/defaults.go

@@ -0,0 +1,44 @@
+package msgformat
+
+import "unicode/utf8"
+
+// DefaultDescriptionCutter cuts description, so len(newDesc) <= maxSize. Ensure that len(desc) >= maxSize and
+// maxSize >= len("...\n").
+func DefaultDescriptionCutter(desc string, maxSize int) string {
+	suffix := "...\n"
+	return desc[:maxSize-len(suffix)] + suffix
+}
+
+// DefaultTagsLimiter cuts and formats tags to fit maxSize. There will be no tag parts, for example:
+//
+// if we have
+//
+//	tags = []string{"tag1", "tag2}
+//	maxSize = 8
+//
+// so call DefaultTagsLimiter(tags, maxSize) will return " [tag1]".
+func DefaultTagsLimiter(tags []string, maxSize int) string {
+	tagsStr := " "
+	lenTagsStr := utf8.RuneCountInString(tagsStr)
+
+	for i := range tags {
+		lenTag := utf8.RuneCountInString(tags[i]) + 2
+
+		if lenTagsStr+lenTag > maxSize {
+			break
+		}
+
+		tagsStr += "[" + tags[i] + "]"
+		lenTagsStr += lenTag
+
+		if lenTagsStr == maxSize {
+			break
+		}
+	}
+
+	if tagsStr == " " {
+		return ""
+	}
+
+	return tagsStr
+}

senders/msgformat/defaults_test.go

@@ -0,0 +1,43 @@
+package msgformat
+
+import (
+	"testing"
+
+	. "github.com/smartystreets/goconvey/convey"
+)
+
+func TestDefaultTagsLimiter(t *testing.T) {
+	Convey("Test default tags limiter", t, func() {
+		tags := []string{"tag1", "tag2"}
+
+		Convey("with maxSize < 0", func() {
+			tagsStr := DefaultTagsLimiter(tags, -1)
+
+			So(tagsStr, ShouldResemble, "")
+		})
+
+		Convey("with maxSize > total characters in tags string", func() {
+			tagsStr := DefaultTagsLimiter(tags, 30)
+
+			So(tagsStr, ShouldResemble, " [tag1][tag2]")
+		})
+
+		Convey("with maxSize not enough for all tags", func() {
+			tagsStr := DefaultTagsLimiter(tags, 8)
+
+			So(tagsStr, ShouldResemble, " [tag1]")
+		})
+
+		Convey("with one long tag > maxSize", func() {
+			tagsStr := DefaultTagsLimiter([]string{"long_tag"}, 4)
+
+			So(tagsStr, ShouldResemble, "")
+		})
+
+		Convey("with no tags", func() {
+			tagsStr := DefaultTagsLimiter([]string{}, 0)
+
+			So(tagsStr, ShouldResemble, "")
+		})
+	})
+}