chore: import upstream snapshot with attribution

internal/forge/classify.go

@@ -0,0 +1,85 @@
+package forge
+
+import "time"
+
+// staleAfterDays is the age past which an open PR is classified STALE
+// (when nothing more pressing applies).
+const staleAfterDays = 30
+
+// Status is the pure-Go classification of a PR against a default base.
+// It carries no network dependency and is table-testable.
+type Status struct {
+	State        string
+	BaseMismatch bool
+	Draft        bool
+	AgeDays      int
+	Blockers     []string
+}
+
+// ClassifyStatus reduces a PR to a single review-state label, computed
+// purely from its already-fetched fields against the repo's default base.
+// State precedence: DRAFT → BASE_MISMATCH → CHANGES_REQUESTED → APPROVED
+// → STALE → READY. Blockers accumulates every condition that would hold
+// a merge.
+func ClassifyStatus(pr PR, defaultBase string) Status {
+	s := Status{
+		Draft:   pr.IsDraft,
+		AgeDays: ageDays(pr.UpdatedAt),
+	}
+	if defaultBase != "" && pr.BaseRef != "" && pr.BaseRef != defaultBase {
+		s.BaseMismatch = true
+	}
+
+	if pr.IsDraft {
+		s.Blockers = append(s.Blockers, "draft")
+	}
+	if s.BaseMismatch {
+		s.Blockers = append(s.Blockers, "base-mismatch")
+	}
+	if pr.ReviewDecision == "CHANGES_REQUESTED" {
+		s.Blockers = append(s.Blockers, "changes-requested")
+	}
+	if RollupCI(pr) == "FAILURE" {
+		s.Blockers = append(s.Blockers, "ci-failure")
+	}
+
+	switch {
+	case pr.IsDraft:
+		s.State = "DRAFT"
+	case s.BaseMismatch:
+		s.State = "BASE_MISMATCH"
+	case pr.ReviewDecision == "CHANGES_REQUESTED":
+		s.State = "CHANGES_REQUESTED"
+	case pr.ReviewDecision == "APPROVED":
+		s.State = "APPROVED"
+	case s.AgeDays >= staleAfterDays:
+		s.State = "STALE"
+	default:
+		s.State = "READY"
+	}
+	return s
+}
+
+// RollupCI echoes a PR's reconstructed CI rollup, normalized to one of
+// NONE / FAILURE / PENDING / SUCCESS. An empty rollup reads as NONE.
+func RollupCI(pr PR) string {
+	switch pr.CIRollup {
+	case "FAILURE", "PENDING", "SUCCESS":
+		return pr.CIRollup
+	default:
+		return "NONE"
+	}
+}
+
+// ageDays returns the whole-day age of t relative to now, clamped at 0
+// for a zero or future timestamp.
+func ageDays(t time.Time) int {
+	if t.IsZero() {
+		return 0
+	}
+	d := time.Since(t)
+	if d < 0 {
+		return 0
+	}
+	return int(d.Hours() / 24)
+}