bug: add a new BugExerpt that hold a subset of a bug state for efficient sorting and retrieval

1 files changed, 92 insertions, 0 deletions

diff --git a/cache/bug_excerpt.go b/cache/bug_excerpt.go
new file mode 100644
index 00000000..23ac459b
--- /dev/null
+++ b/cache/bug_excerpt.go
@@ -0,0 +1,92 @@
+package cache
+
+import (
+	"github.com/MichaelMure/git-bug/bug"
+	"github.com/MichaelMure/git-bug/util"
+)
+
+// BugExcerpt hold a subset of the bug values to be able to sort and filter bugs
+// efficiently without having to read and compile each raw bugs.
+type BugExcerpt struct {
+	Id string
+
+	CreateLamportTime util.LamportTime
+	EditLamportTime   util.LamportTime
+	CreateUnixTime    int64
+	EditUnixTime      int64
+
+	Status bug.Status
+	Author bug.Person
+}
+
+func NewBugExcerpt(b *bug.Bug, snap bug.Snapshot) BugExcerpt {
+	return BugExcerpt{
+		Id:                b.Id(),
+		CreateLamportTime: b.CreateLamportTime(),
+		EditLamportTime:   b.EditLamportTime(),
+		CreateUnixTime:    b.FirstOp().UnixTime(),
+		EditUnixTime:      snap.LastEditUnix(),
+		Status:            snap.Status,
+		Author:            snap.Author,
+	}
+}
+
+/*
+ * Sorting
+ */
+
+type BugsByCreationTime []*BugExcerpt
+
+func (b BugsByCreationTime) Len() int {
+	return len(b)
+}
+
+func (b BugsByCreationTime) Less(i, j int) bool {
+	if b[i].CreateLamportTime < b[j].CreateLamportTime {
+		return true
+	}
+
+	if b[i].CreateLamportTime > b[j].CreateLamportTime {
+		return false
+	}
+
+	// When the logical clocks are identical, that means we had a concurrent
+	// edition. In this case we rely on the timestamp. While the timestamp might
+	// be incorrect due to a badly set clock, the drift in sorting is bounded
+	// by the first sorting using the logical clock. That means that if users
+	// synchronize their bugs regularly, the timestamp will rarely be used, and
+	// should still provide a kinda accurate sorting when needed.
+	return b[i].CreateUnixTime < b[j].CreateUnixTime
+}
+
+func (b BugsByCreationTime) Swap(i, j int) {
+	b[i], b[j] = b[j], b[i]
+}
+
+type BugsByEditTime []*BugExcerpt
+
+func (b BugsByEditTime) Len() int {
+	return len(b)
+}
+
+func (b BugsByEditTime) Less(i, j int) bool {
+	if b[i].EditLamportTime < b[j].EditLamportTime {
+		return true
+	}
+
+	if b[i].EditLamportTime > b[j].EditLamportTime {
+		return false
+	}
+
+	// When the logical clocks are identical, that means we had a concurrent
+	// edition. In this case we rely on the timestamp. While the timestamp might
+	// be incorrect due to a badly set clock, the drift in sorting is bounded
+	// by the first sorting using the logical clock. That means that if users
+	// synchronize their bugs regularly, the timestamp will rarely be used, and
+	// should still provide a kinda accurate sorting when needed.
+	return b[i].EditUnixTime < b[j].EditUnixTime
+}
+
+func (b BugsByEditTime) Swap(i, j int) {
+	b[i], b[j] = b[j], b[i]
+}