package agent

import (
	"errors"
	"os"
	"path/filepath"
	"sync/atomic"
	"testing"
	"time"

	llmgwv1 "gitea.mynodes.xyz/ilker/llmgw/api/gen/llmgw/v1"
)

func settingsAgent(t *testing.T, running string) (*Agent, chan struct{}) {
	t.Helper()
	oldFile, oldExit := SettingsFile, exitForUpgrade
	SettingsFile = filepath.Join(t.TempDir(), "agent-settings.yaml")
	exited := make(chan struct{}, 1)
	exitForUpgrade = func() { exited <- struct{}{} }
	t.Cleanup(func() { SettingsFile, exitForUpgrade = oldFile, oldExit })
	cfg := Config{Server: "127.0.0.1:7443", NodeID: "n1", WeightsCache: t.TempDir(), EnginesDir: t.TempDir(), Settings: running}
	cfg.Superv.WorkDir = t.TempDir()
	a, err := New(cfg, nil, nil)
	if err != nil {
		t.Fatal(err)
	}
	return a, exited
}

// exitedSoon is whether the agent exited within a second: it waits a
// moment for its log line to leave first.
func exitedSoon(ch chan struct{}) bool {
	select {
	case <-ch:
		return true
	case <-time.After(time.Second):
		return false
	}
}

func TestAnAgentOnItsSettingsStaysAndOneOffThemStartsAgain(t *testing.T) {
	a, exited := settingsAgent(t, "heartbeat_interval: 5s\n")
	a.applySettings(&llmgwv1.AgentSettings{Yaml: "heartbeat_interval: 5s\n"})
	if exitedSoon(exited) || ReadSettings() != nil {
		t.Error("settings it already runs on restarted it")
	}
	a.applySettings(&llmgwv1.AgentSettings{Yaml: "heartbeat_interval: 2s\n"})
	if !exitedSoon(exited) || string(ReadSettings()) != "heartbeat_interval: 2s\n" {
		t.Errorf("new settings: kept %q", ReadSettings())
	}
}

func TestSettingsThatWouldNotLoadAreNotTaken(t *testing.T) {
	a, exited := settingsAgent(t, "")
	a.SetSettingsCheck(func([]byte) error { return errors.New("fabric ib-a lists no HCAs") })
	a.applySettings(&llmgwv1.AgentSettings{Yaml: "fabrics: [{name: ib-a}]\n"})
	if exitedSoon(exited) || ReadSettings() != nil {
		t.Error("settings that do not load were taken")
	}
}

func TestAChangedAgentYamlThatLoadsStartsTheAgentAgain(t *testing.T) {
	a, exited := settingsAgent(t, "")
	old := watchEvery
	watchEvery = 10 * time.Millisecond
	t.Cleanup(func() { watchEvery = old })
	p := filepath.Join(t.TempDir(), "agent.yaml")
	_ = os.WriteFile(p, []byte("node_id: n1\n"), 0o600)
	var loads atomic.Bool
	check := func() error {
		if loads.Load() {
			return nil
		}
		return errors.New("broken")
	}
	go a.WatchFile(t.Context(), p, check)
	time.Sleep(30 * time.Millisecond)
	// Saved broken: reported, not restarted into.
	_ = os.WriteFile(p, []byte("node_id: [\n"), 0o600)
	if exitedSoon(exited) {
		t.Fatal("a broken agent.yaml restarted the agent")
	}
	loads.Store(true)
	_ = os.WriteFile(p, []byte("node_id: n1\nlabels: {a: b}\n"), 0o600)
	if !exitedSoon(exited) {
		t.Error("a changed agent.yaml did not restart the agent")
	}
}