package completion

import (
	"context"
	"errors"
	"fmt"
	"testing"
	"time"
)

type fakeRuntimeClient struct {
	closed bool
}

func (f *fakeRuntimeClient) DidOpen(_ context.Context, _ string, _ string, _ int) error {
	return nil
}

func (f *fakeRuntimeClient) DidChange(_ context.Context, _ string, _ string, _ int) error {
	return nil
}

func (f *fakeRuntimeClient) Completion(_ context.Context, _ string, _ int, _ int) (Response, error) {
	return Response{
		Items: []Item{{Label: "ok"}},
	}, nil
}

func (f *fakeRuntimeClient) Close() error {
	f.closed = true
	return nil
}

// 同 language+session 的请求应复用同一个底层 client。
func TestManagerCompleteSelectsLanguageAndSession(t *testing.T) {
	createCount := 0
	factory := func(_ context.Context, spec LanguageServerSpec, _ string) (RuntimeClient, error) {
		createCount++
		if spec.Language != "go" {
			return nil, fmt.Errorf("unexpected language: %s", spec.Language)
		}
		return &fakeRuntimeClient{}, nil
	}

	m := NewManager(ManagerConfig{WorkspaceDir: "."}, []LanguageServerSpec{
		{Language: "go", LanguageID: "go", Command: "gopls"},
	}, factory)
	defer m.Close()

	for i := 0; i < 2; i++ {
		resp, err := m.Complete(context.Background(), Request{
			Language:  "go",
			SessionID: "s1",
			URI:       "file:///main.go",
			Text:      "package main",
			Line:      0,
			Character: 0,
		})
		if err != nil {
			t.Fatalf("Complete() error = %v", err)
		}
		if len(resp.Items) != 1 || resp.Items[0].Label != "ok" {
			t.Fatalf("unexpected response: %+v", resp)
		}
	}

	if createCount != 1 {
		t.Fatalf("expected one client creation, got %d", createCount)
	}
}

// 未配置的语言应返回 ErrUnsupportedLanguage。
func TestManagerCompleteUnsupportedLanguage(t *testing.T) {
	m := NewManager(ManagerConfig{}, []LanguageServerSpec{
		{Language: "go", LanguageID: "go", Command: "gopls"},
	}, func(_ context.Context, _ LanguageServerSpec, _ string) (RuntimeClient, error) {
		return &fakeRuntimeClient{}, nil
	})
	defer m.Close()

	_, err := m.Complete(context.Background(), Request{
		Language:  "python",
		URI:       "file:///main.py",
		Text:      "print('hi')",
		Line:      0,
		Character: 0,
	})
	if !errors.Is(err, ErrUnsupportedLanguage) {
		t.Fatalf("expected ErrUnsupportedLanguage, got %v", err)
	}
}

// 超过空闲 TTL 的会话应被后台清理并关闭 client。
func TestManagerCleanupIdleSession(t *testing.T) {
	client := &fakeRuntimeClient{}
	m := NewManager(ManagerConfig{
		WorkspaceDir:    ".",
		SessionTTL:      30 * time.Millisecond,
		CleanupInterval: 10 * time.Millisecond,
	}, []LanguageServerSpec{
		{Language: "go", LanguageID: "go", Command: "gopls"},
	}, func(_ context.Context, _ LanguageServerSpec, _ string) (RuntimeClient, error) {
		return client, nil
	})
	defer m.Close()

	_, err := m.Complete(context.Background(), Request{
		Language:  "go",
		SessionID: "s2",
		URI:       "file:///main.go",
		Text:      "package main",
		Line:      0,
		Character: 0,
	})
	if err != nil {
		t.Fatalf("Complete() error = %v", err)
	}

	time.Sleep(90 * time.Millisecond)

	sessions := m.ActiveSessions()
	if sessions["go"] != 0 {
		t.Fatalf("expected session cleanup, got %+v", sessions)
	}
	if !client.closed {
		t.Fatal("expected client to be closed by cleanup")
	}
}