Implement resume, skip, and stage selection

internal/app/run_control.go

@@ -0,0 +1,51 @@
+package app
+
+import (
+	"gitea.maximumdirect.net/eric/narratio/internal/manifest"
+	"gitea.maximumdirect.net/eric/narratio/internal/stage"
+)
+
+type stageAction string
+
+const (
+	stageActionRun  stageAction = "run"
+	stageActionSkip stageAction = "skip"
+)
+
+type stageDecision struct {
+	Stage  stage.Stage
+	Action stageAction
+}
+
+func decideStageActions(stages []stage.Stage, m *manifest.Manifest, force bool) []stageDecision {
+	out := make([]stageDecision, 0, len(stages))
+	for _, s := range stages {
+		action := stageActionRun
+		// TODO: incorporate stale detection once checksum/input change tracking is implemented.
+		if !force && stageSucceeded(m, s.Name()) {
+			action = stageActionSkip
+		}
+		out = append(out, stageDecision{
+			Stage:  s,
+			Action: action,
+		})
+	}
+	return out
+}
+
+func stageSucceeded(m *manifest.Manifest, name string) bool {
+	if m == nil || m.Stages == nil {
+		return false
+	}
+	sr := m.Stages[name]
+	return sr != nil && sr.Status == manifest.StatusSucceeded
+}
+
+func firstNonSucceededIndex(stages []stage.Stage, m *manifest.Manifest) int {
+	for i, s := range stages {
+		if !stageSucceeded(m, s.Name()) {
+			return i
+		}
+	}
+	return len(stages)
+}