package reconcile

import (
	"context"
	"errors"
	"path/filepath"
	"sync"
	"testing"

	"gitea.dooplex.hu/admin/felhom-agent/internal/hub"
	"gitea.dooplex.hu/admin/felhom-agent/internal/proxmox"
)

// fakeAPI is a configurable GuestAPI for engine tests: it records mutating calls and
// returns canned UPIDs (""=synchronous, non-empty=async) and WaitTask verdicts.
type fakeAPI struct {
	mu  sync.Mutex
	lxc []proxmox.Guest
	cfg map[int]proxmox.GuestConfig

	startUPID, stopUPID, setUPID string
	startErr, stopErr, setErr    error
	// waitFunc maps a UPID to a (status, err); default = OK. Mirrors the real client,
	// which errors on a non-OK exitstatus.
	waitFunc func(upid string) (proxmox.TaskStatus, error)

	starts  []int
	stops   []int
	sets    []setCall
	waits   []string
	listErr error
}

type setCall struct {
	vmid   int
	params map[string]string
}

func (f *fakeAPI) ListLXC(context.Context) ([]proxmox.Guest, error) {
	if f.listErr != nil {
		return nil, f.listErr
	}
	return f.lxc, nil
}

func (f *fakeAPI) GuestConfig(_ context.Context, vmid int) (proxmox.GuestConfig, error) {
	c, ok := f.cfg[vmid]
	if !ok {
		return proxmox.GuestConfig{}, errors.New("no config")
	}
	return c, nil
}

func (f *fakeAPI) Start(_ context.Context, vmid int) (string, error) {
	f.mu.Lock()
	f.starts = append(f.starts, vmid)
	f.mu.Unlock()
	return f.startUPID, f.startErr
}

func (f *fakeAPI) Stop(_ context.Context, vmid int) (string, error) {
	f.mu.Lock()
	f.stops = append(f.stops, vmid)
	f.mu.Unlock()
	return f.stopUPID, f.stopErr
}

func (f *fakeAPI) SetConfig(_ context.Context, vmid int, params map[string]string) (string, error) {
	f.mu.Lock()
	f.sets = append(f.sets, setCall{vmid, params})
	f.mu.Unlock()
	return f.setUPID, f.setErr
}

func (f *fakeAPI) WaitTask(_ context.Context, upid string, _ proxmox.WaitOptions) (proxmox.TaskStatus, error) {
	f.mu.Lock()
	f.waits = append(f.waits, upid)
	f.mu.Unlock()
	if f.waitFunc != nil {
		return f.waitFunc(upid)
	}
	return proxmox.TaskStatus{Status: "stopped", ExitStatus: "OK"}, nil
}

func newEngine(t *testing.T, api GuestAPI, provider DesiredProvider) (*Engine, *Journal, *Queue) {
	t.Helper()
	jp := filepath.Join(t.TempDir(), "journal.log")
	j, err := OpenJournal(jp)
	if err != nil {
		t.Fatalf("OpenJournal: %v", err)
	}
	t.Cleanup(func() { j.Close() })
	q := NewQueue()
	t.Cleanup(q.Close)
	e := NewEngine(EngineOptions{API: api, Queue: q, Journal: j, Provider: provider})
	return e, j, q
}

func TestEngine_EmptyProviderNoMutations(t *testing.T) {
	api := &fakeAPI{
		lxc: []proxmox.Guest{{VMID: 100, Status: "running"}},
		cfg: map[int]proxmox.GuestConfig{100: {Cores: 2}},
	}
	e, _, _ := newEngine(t, api, EmptyProvider{})
	res, err := e.Reconcile(context.Background())
	if err != nil {
		t.Fatalf("Reconcile: %v", err)
	}
	if res.Planned != 0 || res.Executed != 0 {
		t.Errorf("EmptyProvider should plan nothing, got %+v", res)
	}
	if len(api.starts)+len(api.stops)+len(api.sets) != 0 {
		t.Errorf("EmptyProvider mutated Proxmox: starts=%v stops=%v sets=%v", api.starts, api.stops, api.sets)
	}
}

func TestEngine_AsyncStartWaitsTask(t *testing.T) {
	api := &fakeAPI{
		lxc:       []proxmox.Guest{{VMID: 100, Status: "stopped"}},
		cfg:       map[int]proxmox.GuestConfig{100: {Cores: 2}},
		startUPID: "UPID:demo:start:100:",
	}
	e, j, _ := newEngine(t, api, StaticProvider{State: desired(DesiredGuest{VMID: 100, Run: RunRunning})})
	res, err := e.Reconcile(context.Background())
	if err != nil {
		t.Fatalf("Reconcile: %v", err)
	}
	if res.Executed != 1 || res.Failed != 0 {
		t.Fatalf("want 1 executed, got %+v", res)
	}
	if len(api.starts) != 1 || api.starts[0] != 100 {
		t.Errorf("expected Start(100), got %v", api.starts)
	}
	if len(api.waits) != 1 {
		t.Errorf("async op must WaitTask, got waits=%v", api.waits)
	}
	if len(j.InFlight()) != 0 {
		t.Errorf("no ops should be in-flight after success: %+v", j.InFlight())
	}
}

func TestEngine_SynchronousSetConfigNoWait(t *testing.T) {
	// Empty UPID = PVE applied synchronously (slice-4 proven for description). Must be
	// treated as success WITHOUT a WaitTask call.
	api := &fakeAPI{
		lxc:     []proxmox.Guest{{VMID: 100, Status: "stopped"}},
		cfg:     map[int]proxmox.GuestConfig{100: {Cores: 2}},
		setUPID: "", // synchronous
	}
	e, _, _ := newEngine(t, api, StaticProvider{State: desired(
		DesiredGuest{VMID: 100, Spec: &hub.GuestSpec{Cores: 4, MemoryBytes: mib(2048)}})})
	res, err := e.Reconcile(context.Background())
	if err != nil {
		t.Fatalf("Reconcile: %v", err)
	}
	if res.Executed != 1 {
		t.Fatalf("want 1 executed, got %+v", res)
	}
	if len(api.sets) != 1 || api.sets[0].params["cores"] != "4" {
		t.Errorf("expected SetConfig cores=4, got %v", api.sets)
	}
	if len(api.waits) != 0 {
		t.Errorf("synchronous op must NOT WaitTask, got waits=%v", api.waits)
	}
}

func TestEngine_WaitTaskFailureCountsFailed(t *testing.T) {
	api := &fakeAPI{
		lxc:       []proxmox.Guest{{VMID: 100, Status: "stopped"}},
		cfg:       map[int]proxmox.GuestConfig{100: {Cores: 2}},
		startUPID: "UPID:demo:start:100:",
		waitFunc: func(string) (proxmox.TaskStatus, error) {
			return proxmox.TaskStatus{Status: "stopped", ExitStatus: "got 403"}, errors.New("task failed: got 403")
		},
	}
	e, j, _ := newEngine(t, api, StaticProvider{State: desired(DesiredGuest{VMID: 100, Run: RunRunning})})
	res, err := e.Reconcile(context.Background())
	if err != nil {
		t.Fatalf("Reconcile (pass): %v", err)
	}
	if res.Failed != 1 || res.Executed != 0 {
		t.Fatalf("want 1 failed, got %+v", res)
	}
	// The failed op is journaled terminal (failed), not left in-flight.
	if len(j.InFlight()) != 0 {
		t.Errorf("failed op should be terminal, in-flight=%+v", j.InFlight())
	}
}

func TestEngine_PostErrorCountsFailed(t *testing.T) {
	api := &fakeAPI{
		lxc:      []proxmox.Guest{{VMID: 100, Status: "stopped"}},
		cfg:      map[int]proxmox.GuestConfig{100: {Cores: 2}},
		startErr: errors.New("connection refused"),
	}
	e, _, _ := newEngine(t, api, StaticProvider{State: desired(DesiredGuest{VMID: 100, Run: RunRunning})})
	res, _ := e.Reconcile(context.Background())
	if res.Failed != 1 {
		t.Fatalf("want 1 failed on POST error, got %+v", res)
	}
	if len(api.waits) != 0 {
		t.Errorf("POST error must not reach WaitTask, got %v", api.waits)
	}
}

func TestEngine_ListErrorIsPassFailure(t *testing.T) {
	api := &fakeAPI{listErr: errors.New("api down")}
	e, _, _ := newEngine(t, api, StaticProvider{State: desired(DesiredGuest{VMID: 100, Run: RunRunning})})
	if _, err := e.Reconcile(context.Background()); err == nil {
		t.Error("expected a pass-level error when actual state can't be read")
	}
}