package session

import (
	"os"
	"path/filepath"
	"runtime"
	"testing"

	"nub/internal/llm"
)

func TestStore_CreateAppendLoad_Roundtrip(t *testing.T) {
	dir := t.TempDir()

	st, err := Create(dir)
	if err != nil {
		t.Fatal(err)
	}
	n1 := NewNode("", textMsg(llm.RoleUser, "hello"), NodeMeta{Model: "test-model"})
	must(t, st.Append(n1))
	n2 := NewNode(n1.ID, textMsg(llm.RoleAssistant, "hi there"), NodeMeta{Model: "test-model"})
	must(t, st.Append(n2))
	id := st.ID
	must(t, st.Close())

	loaded, err := Load(dir, id)
	if err != nil {
		t.Fatal(err)
	}
	defer loaded.Close()

	if loaded.Head != n2.ID {
		t.Errorf("head = %s, want %s", loaded.Head, n2.ID)
	}
	msgs := loaded.PathToHead()
	if len(msgs) != 2 || msgs[1].Content[0].Text != "hi there" {
		t.Errorf("unexpected path: %+v", msgs)
	}
}

// TestStore_RewindAndBranch_BothPathsRemainLoadable ist das M2-Fertig-
// Kriterium aus Abschnitt 6: Rewind auf einen früheren Knoten + Weiterarbeit
// erzeugt einen zweiten Ast, beide bleiben ladbar.
func TestStore_RewindAndBranch_BothPathsRemainLoadable(t *testing.T) {
	dir := t.TempDir()

	st, err := Create(dir)
	if err != nil {
		t.Fatal(err)
	}
	root := NewNode("", textMsg(llm.RoleUser, "root"), NodeMeta{})
	must(t, st.Append(root))
	tipA := NewNode(root.ID, textMsg(llm.RoleAssistant, "original continuation"), NodeMeta{})
	must(t, st.Append(tipA))
	id := st.ID
	must(t, st.Close())

	// Rewind: erneut laden, auf root zurückspringen, neu weiterarbeiten.
	resumed, err := Load(dir, id)
	if err != nil {
		t.Fatal(err)
	}
	must(t, resumed.Branch(root.ID))
	tipB := NewNode(root.ID, textMsg(llm.RoleAssistant, "rewound continuation"), NodeMeta{})
	must(t, resumed.Append(tipB))
	must(t, resumed.Close())

	// Beide Äste müssen nach erneutem Laden noch da sein.
	final, err := Load(dir, id)
	if err != nil {
		t.Fatal(err)
	}
	defer final.Close()

	if _, ok := final.Nodes[tipA.ID]; !ok {
		t.Error("original branch tip missing after reload")
	}
	if _, ok := final.Nodes[tipB.ID]; !ok {
		t.Error("rewound branch tip missing after reload")
	}
	if final.Head != tipB.ID {
		t.Errorf("head after reload = %s, want %s (latest branch)", final.Head, tipB.ID)
	}

	must(t, final.Branch(tipA.ID))
	msgsA := final.PathToHead()
	if got := msgsA[len(msgsA)-1].Content[0].Text; got != "original continuation" {
		t.Errorf("branch A tip = %q", got)
	}

	must(t, final.Branch(tipB.ID))
	msgsB := final.PathToHead()
	if got := msgsB[len(msgsB)-1].Content[0].Text; got != "rewound continuation" {
		t.Errorf("branch B tip = %q", got)
	}
}

func TestStore_FilePermissions(t *testing.T) {
	if runtime.GOOS == "windows" {
		t.Skip("Unix-Dateirechte, siehe Abschnitt 9 (kein Windows-Pfad)")
	}
	dir := t.TempDir()
	st, err := Create(dir)
	if err != nil {
		t.Fatal(err)
	}
	defer st.Close()

	dirInfo, err := os.Stat(filepath.Join(dir, ".nub", "sessions"))
	if err != nil {
		t.Fatal(err)
	}
	if perm := dirInfo.Mode().Perm(); perm != 0o700 {
		t.Errorf(".nub/sessions perm = %o, want 0700", perm)
	}

	fileInfo, err := os.Stat(filepath.Join(dir, ".nub", "sessions", st.ID+".jsonl"))
	if err != nil {
		t.Fatal(err)
	}
	if perm := fileInfo.Mode().Perm(); perm != 0o600 {
		t.Errorf("session file perm = %o, want 0600", perm)
	}
}

func TestStore_Load_RejectsUnsupportedVersion(t *testing.T) {
	dir := t.TempDir()
	sessDir := filepath.Join(dir, ".nub", "sessions")
	must(t, os.MkdirAll(sessDir, 0o700))
	path := filepath.Join(sessDir, "bad.jsonl")
	must(t, os.WriteFile(path, []byte(`{"v":2,"node":{"id":"x"}}`+"\n"), 0o600))

	if _, err := Load(dir, "bad"); err == nil {
		t.Fatal("expected error for unsupported record version")
	}
}

func TestStore_List_ReturnsSessionsNewestFirst(t *testing.T) {
	dir := t.TempDir()

	st1, err := Create(dir)
	if err != nil {
		t.Fatal(err)
	}
	must(t, st1.Append(NewNode("", textMsg(llm.RoleUser, "first session"), NodeMeta{})))
	must(t, st1.Close())

	st2, err := Create(dir)
	if err != nil {
		t.Fatal(err)
	}
	must(t, st2.Append(NewNode("", textMsg(llm.RoleUser, "second session"), NodeMeta{})))
	must(t, st2.Close())

	infos, err := List(dir)
	if err != nil {
		t.Fatal(err)
	}
	if len(infos) != 2 {
		t.Fatalf("len = %d, want 2", len(infos))
	}
	found := map[string]bool{}
	for _, info := range infos {
		found[info.Summary] = true
	}
	if !found["first session"] || !found["second session"] {
		t.Errorf("infos = %+v", infos)
	}
}