package system

import (
	"context"
	"testing"
)

// How a one-shot unit's state is read: what it did, not whether a process is up.
//
// **A one-shot that did its work and exited is satisfied, not stopped.** Its unit loads a rule set
// and exits, so it is inactive the instant it succeeds; reading that as stopped made the firewall
// permanently unsatisfiable, on every apply, with the rules correctly in place the whole time.
//
// **One that failed is still stopped**, or the host would report success for work that did not
// happen — the opposite mistake and the worse one.
//
// **One that never ran is stopped** (novox/hq issue 1126, the kernel's boot-time cleanup on ace):
// systemd says ExecMainStatus=0 for a unit that never ran exactly as for one that succeeded, and
// only its start timestamp separates them. Read as "running", a package's one-shot declared
// running was never started, and one declared stopped could never be.
//
// **At rest** is whether a one-shot that does not linger has nothing running now: a declaration
// that it be stopped is then satisfied, whatever it last did, because there is nothing to stop.
func TestAOneShotIsReadByWhatItDid(t *testing.T) {
	for _, c := range []struct {
		name, show, want string
		atRest           bool
	}{
		{"finished", "ActiveState=inactive\nType=oneshot\nRemainAfterExit=no\nExecMainStatus=0\n" +
			"ExecMainStartTimestampMonotonic=5123456\n", "running", true},
		{"finished, no timestamp read", "ActiveState=inactive\nType=oneshot\nRemainAfterExit=no\n" +
			"ExecMainStatus=0\n", "running", true},
		{"failed", "ActiveState=inactive\nType=oneshot\nRemainAfterExit=no\nExecMainStatus=1\n" +
			"ExecMainStartTimestampMonotonic=5123456\n", "stopped", true},
		{"never ran", "ActiveState=inactive\nType=oneshot\nRemainAfterExit=no\nExecMainStatus=0\n" +
			"ExecMainStartTimestampMonotonic=0\n", "stopped", true},
		{"running now", "ActiveState=activating\nType=oneshot\nRemainAfterExit=no\nExecMainStatus=0\n" +
			"ExecMainStartTimestampMonotonic=5123456\n", "running", false},
		{"lingers", "ActiveState=active\nType=oneshot\nRemainAfterExit=yes\nExecMainStatus=0\n",
			"running", false},
		{"a daemon, stopped", "ActiveState=inactive\nType=simple\nRemainAfterExit=no\nExecMainStatus=0\n",
			"stopped", false},
	} {
		t.Run(c.name, func(t *testing.T) {
			run := func(_ context.Context, _ string, _ ...string) (string, error) {
				return "LoadState=loaded\n" + c.show, nil
			}
			state, err := arch{}.ServiceState(context.Background(), run, "thing.service")
			if err != nil {
				t.Fatalf("read as an error: %v", err)
			}
			if state != c.want {
				t.Errorf("reads as %q, want %q", state, c.want)
			}
			rest, err := arch{}.ServiceAtRest(context.Background(), run, "thing.service")
			if err != nil {
				t.Fatalf("at rest read as an error: %v", err)
			}
			if rest != c.atRest {
				t.Errorf("at rest is %v, want %v", rest, c.atRest)
			}
		})
	}
}