package witness

import (
	"encoding/json"
	"strings"
	"testing"
	"time"

	"github.com/novox/mesh-host/internal/link"
)

// The contract, held. Each of these is a line the controller's side relies on or writes; a change on
// either side changes this test (novox/hq to-be 45 §8).

// The lease is read where the controller keeps it (ADR 0229), on the one subject a host's grant names.
func TestTheLeaseIsReadWhereTheControllerKeepsIt(t *testing.T) {
	if LeaseBucket != "mesh-controller_lease" || LeaseKey != "holder" {
		t.Fatalf("the lease is read from %s/%s; the controller keeps it in mesh-controller_lease/holder",
			LeaseBucket, LeaseKey)
	}
	if got := link.DirectGetSubject(LeaseBucket, LeaseKey); got != "$JS.API.DIRECT.GET.KV_mesh-controller_lease.$KV.mesh-controller_lease.holder" {
		t.Fatalf("the host asks %s for the lease; its grant names exactly the direct get of the key", got)
	}
	if LeaseAge != 15*time.Second {
		t.Fatalf("the lease's age is %s; the controller's bucket keeps a key fifteen seconds", LeaseAge)
	}
}

// What the controller writes — mesh-controller internal/lease Holder, by its JSON names — is what is
// read. The value below is the shape that Holder marshals to.
func TestTheLeaseValueIsTheControllersHolder(t *testing.T) {
	written := `{"instance":"controller@anchor pid 4242 since 2026-10-06T10:00:00Z","host":"anchor",` +
		`"build":"development build","epoch":57,"taken":"2026-10-06T10:00:01Z","renewed":"2026-10-06T10:00:31Z"}`
	l, err := ParseLease([]byte(written))
	if err != nil {
		t.Fatal(err)
	}
	if l.Instance == "" || l.Host != "anchor" || l.Epoch != 57 || l.Taken.IsZero() || l.Renewed.IsZero() {
		t.Fatalf("the lease was not read whole: %+v", l)
	}
	// And a field the controller adds later does not stop it being read.
	if _, err := ParseLease([]byte(`{"instance":"i","taken":"2026-10-06T10:00:01Z","renewed":"2026-10-06T10:00:01Z","bundle":"sha256:x"}`)); err != nil {
		t.Fatalf("a lease value with a field this host does not know was refused: %v", err)
	}
}

// Healthy is: held now, on this machine, by an instance that took it after the new build started.
func TestTheNewControllerHoldsTheLeaseOnlyWhenItTookItAfterItStarted(t *testing.T) {
	started := time.Date(2026, 10, 6, 10, 0, 0, 0, time.UTC)
	now := started.Add(30 * time.Second)
	held := ControllerLease{Instance: "controller@anchor pid 2 since …", Host: "anchor.example",
		Taken: started.Add(3 * time.Second), Renewed: now.Add(-2 * time.Second), Epoch: 58}
	for _, c := range []struct {
		name string
		l    ControllerLease
		want bool
		says string
	}{
		{"held by the new instance", held, true, "holds the lease"},
		{"nobody", ControllerLease{}, false, "no holder"},
		{"the old instance, taken before the restart", func() ControllerLease {
			l := held
			l.Taken = started.Add(-time.Hour)
			return l
		}(), false, "before the new build started"},
		{"another machine's controller", func() ControllerLease {
			l := held
			l.Host = "home-server"
			return l
		}(), false, "not this machine"},
		{"taken and no longer renewed", func() ControllerLease {
			l := held
			l.Renewed = now.Add(-20 * time.Second)
			return l
		}(), false, "past its"},
		{"taken within the clocks' skew of the start", func() ControllerLease {
			l := held
			l.Taken = started.Add(-time.Second)
			return l
		}(), true, "holds the lease"},
	} {
		got, why := c.l.HeldBySince("anchor", started, now)
		if got != c.want || !strings.Contains(why, c.says) {
			t.Errorf("%s: healthy %v (%s), want %v saying %q", c.name, got, why, c.want, c.says)
		}
	}
}

// The runtime is asked by its own name and this machine's: only this machine's runtime can answer.
func TestTheRuntimeIsAskedByItsNameAndThisMachines(t *testing.T) {
	if got := link.PingSubject(NodeToolsService, "anchor"); got != "$SRV.PING.node-tools.anchor" {
		t.Fatalf("the host asks %s; the runtime answers $SRV.PING.node-tools.<node>", got)
	}
}

// What is judged by default is the mesh's two core processes, by the names the controller composes
// them under, and nothing else.
func TestOnlyTheCoreProcessesAreJudgedByDefault(t *testing.T) {
	for name, want := range map[string]string{"mesh-controller": ByLease, "node-tools": ByPing, "greeter": ByNone} {
		if got := Default(name); got != want {
			t.Errorf("%s is judged by %q, want %q", name, got, want)
		}
	}
	if ControllerWithin != 60*time.Second || NodeToolsWithin != 60*time.Second || PingWithin != 5*time.Second {
		t.Fatal("the bounds are to-be 45 §8's: the lease within sixty seconds, a PING answered within five")
	}
}

// A verdict on the wire names its component as the controller's condition does.
func TestAVerdictNamesItsComponent(t *testing.T) {
	raw, _ := json.Marshal(link.Rollback{Component: Component(ByLease), Outcome: link.RolledBack})
	if !strings.Contains(string(raw), `"component":"controller"`) || Component(ByPing) != "node-tools" {
		t.Fatalf("a verdict names its component as %s", raw)
	}
}