Answer the build queue as data too, so a check can say how far back it waits

The queue verb answered only a table, so nothing outside the controller
could say an ask's place in the queue. It now asks its command for JSON:
each ask's state, kind, repository, commit, machine, since and position
among the waiting, with the table carried beside it and answered as the
verb's output, both written from one read. A repository's password, if
one were ever written into it, is left out of what is shown.

novox/hq issue 455

cmd/mesh-controller/queue.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"regexp"
 	"sort"
 	"strings"
 	"time"
@@ -67,18 +68,95 @@ func listQueue(ctx context.Context, args []string, w io.Writer) error {
 	if err != nil {
 		return err
 	}
+	now := time.Now()
 	if *asJSON {
-		body, err := json.MarshalIndent(q, "", "  ")
+		body, err := json.MarshalIndent(queueAnswerOf(q, now), "", "  ")
 		if err != nil {
 			return err
 		}
 		fmt.Fprintln(w, string(body))
 		return nil
 	}
-	fmt.Fprint(w, queueText(q, time.Now()))
+	fmt.Fprint(w, queueText(q, now))
 	return nil
 }
 
+// queueAnswer is the queue as data (novox/hq issue 455): what a caller reads to say how far back an ask
+// waits — "waiting in the build queue behind 2" — which the table alone could not tell it. Text is the
+// table, written from the same read: the verb answers it as its output and the rest as its answer, so the
+// two never disagree.
+type queueAnswer struct {
+	Seat       string         `json:"seat"`
+	Waiting    int            `json:"waiting"`
+	InFlight   int            `json:"in-flight"`
+	Dead       int            `json:"dead"`
+	MaxDeliver int            `json:"max-deliver"`
+	Asks       []queuedAnswer `json:"asks"`
+	Text       string         `json:"text"`
+}
+
+// queuedAnswer is one ask as data. Never what the request carries beyond its source — not `held`, every
+// artifact the mesh has built, nor a check's checkouts beside it.
+type queuedAnswer struct {
+	ID    string `json:"id"`
+	State string `json:"state"`
+	// Kind is "check" for a pull request's merge check, "build" for anything else.
+	Kind       string `json:"kind"`
+	Repository string `json:"repository"`
+	Path       string `json:"path,omitempty"`
+	Ref        string `json:"ref,omitempty"`
+	// Commit is the ref when it names a commit; empty when the ask follows a branch or the default.
+	Commit string `json:"commit,omitempty"`
+	// Machine is the one building an ask in flight; WasOn the one that started it and handed it back.
+	Machine string    `json:"machine,omitempty"`
+	WasOn   string    `json:"was-on,omitempty"`
+	AskedAt time.Time `json:"asked-at,omitzero"`
+	// Since is when the ask came to its state: its start on the machine for one in flight that a
+	// machine said it started, otherwise when it was asked.
+	Since time.Time `json:"since,omitzero"`
+	// Position is its place among the waiting, 1 being handed out next; 0 for an ask not waiting.
+	Position int    `json:"position,omitempty"`
+	Seq      uint64 `json:"seq"`
+}
+
+// aCommitRef is a ref that names a commit by its full hash (SHA-1 or SHA-256).
+var aCommitRef = regexp.MustCompile(`^(?:[0-9a-f]{40}|[0-9a-f]{64})$`)
+
+// queueAnswerOf is the queue as data, in the table's order: in flight, the waiting from the next one to
+// be handed out, then the dead. A pure function of one read (novox/hq issue 455).
+func queueAnswerOf(q link.Queue, now time.Time) queueAnswer {
+	waiting, running, dead := q.Of(link.AskWaiting), q.Of(link.AskInFlight), q.Of(link.AskDead)
+	out := queueAnswer{Seat: q.Seat, Waiting: len(waiting), InFlight: len(running), Dead: len(dead),
+		MaxDeliver: q.MaxDeliver, Asks: []queuedAnswer{}, Text: queueText(q, now)}
+	one := func(a link.QueuedAsk, position int) queuedAnswer {
+		kind := "build"
+		if a.Request.Check != nil {
+			kind = "check"
+		}
+		since := a.AskedAt
+		if a.State == link.AskInFlight && a.On != "" && !a.Started.IsZero() {
+			since = a.Started
+		}
+		commit := ""
+		if aCommitRef.MatchString(a.Ref) {
+			commit = a.Ref
+		}
+		return queuedAnswer{ID: a.ID, State: a.State, Kind: kind, Repository: link.WithoutPassword(a.Repository), Path: a.Path,
+			Ref: a.Ref, Commit: commit, Machine: a.On, WasOn: a.Was, AskedAt: a.AskedAt, Since: since,
+			Position: position, Seq: a.Seq}
+	}
+	for _, a := range running {
+		out.Asks = append(out.Asks, one(a, 0))
+	}
+	for i, a := range waiting {
+		out.Asks = append(out.Asks, one(a, i+1))
+	}
+	for _, a := range dead {
+		out.Asks = append(out.Asks, one(a, 0))
+	}
+	return out
+}
+
 // queueText is the queue as a person reads it: a summary line, then each kind in queue order.
 // Never what an ask carries as `held` — that is every artifact the mesh has built.
 func queueText(q link.Queue, now time.Time) string {
@@ -92,7 +170,7 @@ func queueText(q link.Queue, now time.Time) string {
 		return "asked " + now.Sub(t).Round(time.Second).String() + " ago"
 	}
 	what := func(a link.QueuedAsk) string {
-		s := a.Repository
+		s := link.WithoutPassword(a.Repository)
 		if a.Path != "" {
 			s += " at " + a.Path
 		}