package main

import (
	"bytes"
	"context"
	"errors"
	"os"
	"path/filepath"
	"testing"
	"time"

	tea "github.com/charmbracelet/bubbletea"
)

type switchService struct {
	prs     []PullRequest
	details PRDetails
	err     error
}

type countingCachedService struct {
	liveDetailsCalls   int
	cachedDetailsCalls int
}

func (s *countingCachedService) ListPullRequests(context.Context, string, string, int, bool) ([]PullRequest, error) {
	return nil, nil
}

func (s *countingCachedService) GetPullRequest(context.Context, string, string, int) (PRDetails, error) {
	return PRDetails{}, nil
}

func (s *countingCachedService) LivePullRequests(context.Context, string, string, int, bool) ([]PullRequest, error) {
	return nil, nil
}

func (s *countingCachedService) LivePullRequest(context.Context, string, string, int) (PRDetails, error) {
	s.liveDetailsCalls++
	return PRDetails{}, nil
}

func (s *countingCachedService) CachedPullRequests(string, string, int, bool) ([]PullRequest, error) {
	return nil, nil
}

func (s *countingCachedService) CachedPullRequest(string, string, int) (PRDetails, error) {
	s.cachedDetailsCalls++
	return PRDetails{}, nil
}

func (s *switchService) ListPullRequests(context.Context, string, string, int, bool) ([]PullRequest, error) {
	return s.prs, s.err
}

func (s *switchService) GetPullRequest(context.Context, string, string, int) (PRDetails, error) {
	return s.details, s.err
}

func TestCachedServiceFallsBackToRecentReadData(t *testing.T) {
	remote := &switchService{
		prs:     []PullRequest{{ID: "pr", Owner: "o", Repository: "r", Number: 1}},
		details: PRDetails{PullRequest: PullRequest{ID: "pr", Owner: "o", Repository: "r", Number: 1}},
	}
	service := NewCachedGitHubService(remote, t.TempDir(), time.Hour)
	if _, err := service.ListPullRequests(context.Background(), "o", "r", 50, false); err != nil {
		t.Fatal(err)
	}
	if _, err := service.GetPullRequest(context.Background(), "o", "r", 1); err != nil {
		t.Fatal(err)
	}
	remote.err = errors.New("offline")
	prs, err := service.ListPullRequests(context.Background(), "o", "r", 50, false)
	if err != nil || len(prs) != 1 || !prs[0].FromCache || prs[0].CachedAt.IsZero() {
		t.Fatalf("cached PR list = %#v, error = %v", prs, err)
	}
	details, err := service.GetPullRequest(context.Background(), "o", "r", 1)
	if err != nil || !details.FromCache || details.CachedAt.IsZero() {
		t.Fatalf("cached details = %#v, error = %v", details, err)
	}
}

func TestReadStateSurvivesRestartWithUnreadComment(t *testing.T) {
	path := filepath.Join(t.TempDir(), "state.json")
	settings := defaultAppSettings()
	settings.ReadState = loadReadState(path)
	m := NewAppWithSettings(nil, "o", "r", false, 50, time.Second, settings)
	initial := PRDetails{
		PullRequest: PullRequest{ID: "pr"},
		Threads:     []ReviewThread{{ID: "thread", Comments: []ReviewComment{{ID: "old"}}}},
	}
	m.trackThreadUpdates(initial)
	updated := initial
	updated.Threads[0].Comments = append(updated.Threads[0].Comments, ReviewComment{ID: "new"})
	m.trackThreadUpdates(updated)
	if !m.unreadThreads["thread"] {
		t.Fatal("new comment was not unread before restart")
	}

	settings.ReadState = loadReadState(path)
	restarted := NewAppWithSettings(nil, "o", "r", false, 50, time.Second, settings)
	restarted.trackThreadUpdates(updated)
	if !restarted.unreadThreads["thread"] {
		t.Fatal("unread comment was lost across restart")
	}
}

func TestCachedPickerSnapshotStaysVisibleWhileLiveRefreshContinues(t *testing.T) {
	m := NewApp(nil, "", "", false, 50, time.Second)
	m.loading = true
	cachedAt := time.Now().Add(-time.Hour)
	updated, _ := m.Update(prsLoadedMsg{
		cached: true,
		prs: []PullRequest{{
			ID: "cached", Number: 1, FromCache: true, CachedAt: cachedAt,
		}},
	})
	m = updated.(App)
	if len(m.prs) != 1 || !m.prs[0].FromCache || !m.loading {
		t.Fatalf("cached snapshot was not shown during refresh: %#v", m)
	}

	updated, _ = m.Update(prsLoadedMsg{prs: []PullRequest{{ID: "live", Number: 2}}})
	m = updated.(App)
	if len(m.prs) != 1 || m.prs[0].ID != "live" || m.loading {
		t.Fatalf("live response did not replace cached snapshot: %#v", m)
	}
}

func TestRoutineRefreshDoesNotReplayCachedDetails(t *testing.T) {
	service := &countingCachedService{}
	m := NewApp(service, "o", "r", false, 50, time.Second)
	pr := PullRequest{Owner: "o", Repository: "r", Number: 1}

	if msg := m.loadDetails(pr, false)(); msg == nil {
		t.Fatal("live refresh returned no message")
	}
	if service.liveDetailsCalls != 1 || service.cachedDetailsCalls != 0 {
		t.Fatalf("routine refresh calls: live=%d cached=%d", service.liveDetailsCalls, service.cachedDetailsCalls)
	}

	msg := m.loadDetails(pr, true)()
	batch, ok := msg.(tea.BatchMsg)
	if !ok {
		t.Fatalf("initial load command returned %T, want tea.BatchMsg", msg)
	}
	for _, command := range batch {
		_ = command()
	}
	if service.liveDetailsCalls != 2 || service.cachedDetailsCalls != 1 {
		t.Fatalf("initial load calls: live=%d cached=%d", service.liveDetailsCalls, service.cachedDetailsCalls)
	}
}

func TestCacheDoesNotRewriteUnchangedContent(t *testing.T) {
	remote := &switchService{details: PRDetails{
		PullRequest: PullRequest{ID: "pr", Owner: "o", Repository: "r", Number: 1, Title: "same"},
	}}
	service := NewCachedGitHubService(remote, t.TempDir(), time.Hour)
	if _, err := service.LivePullRequest(context.Background(), "o", "r", 1); err != nil {
		t.Fatal(err)
	}
	path := service.file(service.pullRequestKey("o", "r", 1))
	before, err := os.ReadFile(path)
	if err != nil {
		t.Fatal(err)
	}
	time.Sleep(2 * time.Millisecond)
	if _, err := service.LivePullRequest(context.Background(), "o", "r", 1); err != nil {
		t.Fatal(err)
	}
	after, err := os.ReadFile(path)
	if err != nil {
		t.Fatal(err)
	}
	if !bytes.Equal(before, after) {
		t.Fatal("unchanged cache content was rewritten")
	}

	remote.details.Title = "changed"
	if _, err := service.LivePullRequest(context.Background(), "o", "r", 1); err != nil {
		t.Fatal(err)
	}
	changed, err := os.ReadFile(path)
	if err != nil {
		t.Fatal(err)
	}
	if bytes.Equal(after, changed) {
		t.Fatal("changed cache content was not persisted")
	}
}