package session

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

	"agentu/internal/llm"
)

func tempStore(t *testing.T) *Store {
	t.Helper()
	dir := t.TempDir()
	store, err := NewStore(dir)
	if err != nil {
		t.Fatal(err)
	}
	return store
}

func TestSaveAndLoad(t *testing.T) {
	store := tempStore(t)
	sess := &Session{
		ID:       GenerateID(),
		Name:     "test session",
		Provider: "loveuer",
		Model:    "deepseek-v4-flash",
		Messages: []llm.Message{
			{Role: llm.RoleSystem, Content: "you are helpful"},
			{Role: llm.RoleUser, Content: "hello"},
			{Role: llm.RoleAssistant, Content: "hi there"},
		},
		LastUsage: &llm.Usage{PromptTokens: 10, CompletionTokens: 5, TotalTokens: 15},
	}
	if err := store.Save(sess); err != nil {
		t.Fatalf("save: %v", err)
	}

	loaded, err := store.Load(sess.ID)
	if err != nil {
		t.Fatalf("load: %v", err)
	}
	if loaded.ID != sess.ID {
		t.Errorf("ID = %q, want %q", loaded.ID, sess.ID)
	}
	if loaded.Name != sess.Name {
		t.Errorf("Name = %q, want %q", loaded.Name, sess.Name)
	}
	if len(loaded.Messages) != 3 {
		t.Errorf("Messages len = %d, want 3", len(loaded.Messages))
	}
	if loaded.Messages[1].Content != "hello" {
		t.Errorf("Messages[1].Content = %q, want %q", loaded.Messages[1].Content, "hello")
	}
	if loaded.LastUsage == nil || loaded.LastUsage.TotalTokens != 15 {
		t.Errorf("LastUsage = %#v", loaded.LastUsage)
	}
	if loaded.UpdatedAt.IsZero() {
		t.Error("UpdatedAt should be set")
	}
}

func TestLoadNotFound(t *testing.T) {
	store := tempStore(t)
	_, err := store.Load("nonexistent")
	if err == nil {
		t.Fatal("expected error for nonexistent session")
	}
}

func TestList(t *testing.T) {
	store := tempStore(t)
	// Empty list
	metas, err := store.List()
	if err != nil {
		t.Fatalf("list: %v", err)
	}
	if len(metas) != 0 {
		t.Errorf("expected empty list, got %d", len(metas))
	}

	// Save two sessions
	store.Save(&Session{ID: "aaa", Name: "first", Messages: []llm.Message{{Role: "user", Content: "a"}}})
	store.Save(&Session{ID: "bbb", Name: "second", Messages: []llm.Message{{Role: "user", Content: "b"}, {Role: "assistant", Content: "c"}}})

	metas, err = store.List()
	if err != nil {
		t.Fatalf("list: %v", err)
	}
	if len(metas) != 2 {
		t.Fatalf("expected 2 sessions, got %d", len(metas))
	}
	// Sorted by updated_at desc
	if metas[0].ID != "bbb" && metas[0].ID != "aaa" {
		t.Errorf("unexpected first session ID: %q", metas[0].ID)
	}
}

func TestDelete(t *testing.T) {
	store := tempStore(t)
	store.Save(&Session{ID: "todelete", Name: "temp"})

	if err := store.Delete("todelete"); err != nil {
		t.Fatalf("delete: %v", err)
	}
	_, err := store.Load("todelete")
	if err == nil {
		t.Fatal("expected error after delete")
	}
}

func TestDeleteNotFound(t *testing.T) {
	store := tempStore(t)
	err := store.Delete("nonexistent")
	if err == nil {
		t.Fatal("expected error for nonexistent delete")
	}
}

func TestSaveRequiresID(t *testing.T) {
	store := tempStore(t)
	err := store.Save(&Session{Name: "no id"})
	if err == nil {
		t.Fatal("expected error for empty ID")
	}
}

func TestGenerateID(t *testing.T) {
	id := GenerateID()
	if len(id) != 8 {
		t.Errorf("ID length = %d, want 8", len(id))
	}
	id2 := GenerateID()
	if id == id2 {
		t.Error("expected unique IDs")
	}
}

func TestDefaultName(t *testing.T) {
	tests := []struct {
		name     string
		messages []llm.Message
		want     string
	}{
		{"empty", nil, ""},
		{"no user msg", []llm.Message{{Role: "system", Content: "hi"}}, ""},
		{"short", []llm.Message{{Role: "user", Content: "hello world"}}, "hello world"},
		{"long", []llm.Message{{Role: "user", Content: "this is a really long message that should be truncated at some point in the middle"}}, "this is a really long message that..."},
		{"multiline", []llm.Message{{Role: "user", Content: "first line\nsecond line"}}, "first line"},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got := DefaultName(tt.messages)
			if got != tt.want {
				t.Errorf("DefaultName = %q, want %q", got, tt.want)
			}
		})
	}
}

func TestNewStoreCreatesDir(t *testing.T) {
	dir := filepath.Join(t.TempDir(), "nested", "sessions")
	store, err := NewStore(dir)
	if err != nil {
		t.Fatalf("NewStore: %v", err)
	}
	info, err := os.Stat(store.dir)
	if err != nil {
		t.Fatalf("stat: %v", err)
	}
	if !info.IsDir() {
		t.Error("expected directory")
	}
}