package syncer

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

	"github.com/arnef/toni-sync/internal/tonieapi"
)

// fakeClient is a minimal in-memory stand-in for tonieapi.Client used in tests.
type fakeClient struct {
	tonieSequence []tonieapi.CreativeTonie // consumed in order by GetCreativeTonie calls
	callIndex     int

	uploadedTitles []string
	sortedTitles   []string
}

func (f *fakeClient) GetCreativeTonie(tonieID string) (*tonieapi.CreativeTonie, error) {
	t := f.tonieSequence[f.callIndex]
	if f.callIndex < len(f.tonieSequence)-1 {
		f.callIndex++
	}
	return &t, nil
}

func (f *fakeClient) UploadFileToTonie(tonie tonieapi.CreativeTonie, filePath, title string) error {
	f.uploadedTitles = append(f.uploadedTitles, title)
	return nil
}

func (f *fakeClient) SortChaptersOfTonie(tonie tonieapi.CreativeTonie, chapters []tonieapi.Chapter) error {
	for _, c := range chapters {
		f.sortedTitles = append(f.sortedTitles, c.Title)
	}
	return nil
}

func makeTonie(chapters []tonieapi.Chapter) tonieapi.CreativeTonie {
	return tonieapi.CreativeTonie{ID: "t1", HouseholdID: "h1", Name: "Test Tonie", Chapters: chapters}
}

func setupFolder(t *testing.T) string {
	t.Helper()
	dir := t.TempDir()
	if err := os.WriteFile(filepath.Join(dir, "01 - First.mp3"), []byte("data"), 0o644); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(dir, "02 - Second.mp3"), []byte("data"), 0o644); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(dir, "notes.txt"), []byte("ignore me"), 0o644); err != nil {
		t.Fatal(err)
	}
	return dir
}

func TestListLocalTracksFiltersByExtension(t *testing.T) {
	dir := setupFolder(t)
	tracks, err := ListLocalTracks(dir)
	if err != nil {
		t.Fatal(err)
	}
	if len(tracks) != 2 || tracks[0].Title != "01 - First" || tracks[1].Title != "02 - Second" {
		t.Fatalf("unexpected tracks: %+v", tracks)
	}
}

func TestListLocalTracksMissingFolder(t *testing.T) {
	if _, err := ListLocalTracks(filepath.Join(t.TempDir(), "missing")); err == nil {
		t.Fatal("expected error for missing folder")
	}
}

func TestBuildPlanDetectsUploadNoRemoval(t *testing.T) {
	dir := setupFolder(t)
	tonie := makeTonie([]tonieapi.Chapter{{ID: "c1", Title: "01 - First"}})
	client := &fakeClient{tonieSequence: []tonieapi.CreativeTonie{tonie}}

	m := Target{TonieID: "t1", Folder: dir, Prune: true}
	plan, err := BuildPlan(client, m)
	if err != nil {
		t.Fatal(err)
	}

	if len(plan.ToUpload) != 1 || plan.ToUpload[0].Title != "02 - Second" {
		t.Fatalf("expected upload of '02 - Second', got %+v", plan.ToUpload)
	}
	if len(plan.ToRemove) != 0 {
		t.Fatalf("expected no removal, got %+v", plan.ToRemove)
	}
	if !plan.NeedsChanges() {
		t.Fatal("expected NeedsChanges to be true")
	}
}

func TestBuildPlanPrunesRemovedChapters(t *testing.T) {
	dir := setupFolder(t)
	tonie := makeTonie([]tonieapi.Chapter{{ID: "c1", Title: "01 - First"}, {ID: "c2", Title: "stale"}})
	client := &fakeClient{tonieSequence: []tonieapi.CreativeTonie{tonie}}

	m := Target{TonieID: "t1", Folder: dir, Prune: true}
	plan, err := BuildPlan(client, m)
	if err != nil {
		t.Fatal(err)
	}
	if len(plan.ToRemove) != 1 || plan.ToRemove[0].Title != "stale" {
		t.Fatalf("expected 'stale' to be removed, got %+v", plan.ToRemove)
	}
}

func TestBuildPlanNoPruneKeepsStaleChapters(t *testing.T) {
	dir := setupFolder(t)
	tonie := makeTonie([]tonieapi.Chapter{{ID: "c1", Title: "01 - First"}, {ID: "c2", Title: "stale"}})
	client := &fakeClient{tonieSequence: []tonieapi.CreativeTonie{tonie}}

	m := Target{TonieID: "t1", Folder: dir, Prune: false}
	plan, err := BuildPlan(client, m)
	if err != nil {
		t.Fatal(err)
	}
	if len(plan.ToRemove) != 0 {
		t.Fatalf("expected no removal, got %+v", plan.ToRemove)
	}
	want := []string{"01 - First", "02 - Second", "stale"}
	if !equalStrings(plan.FinalOrderTitles, want) {
		t.Fatalf("expected order %v, got %v", want, plan.FinalOrderTitles)
	}
}

func TestBuildPlanSkipsEmptyFolder(t *testing.T) {
	dir := t.TempDir() // no audio files
	tonie := makeTonie([]tonieapi.Chapter{{ID: "c1", Title: "existing chapter"}})
	client := &fakeClient{tonieSequence: []tonieapi.CreativeTonie{tonie}}

	m := Target{TonieID: "t1", Folder: dir, Prune: true}
	plan, err := BuildPlan(client, m)
	if err != nil {
		t.Fatal(err)
	}

	if !plan.Skipped {
		t.Fatal("expected plan to be skipped for empty folder")
	}
	if plan.NeedsChanges() {
		t.Fatal("expected NeedsChanges to be false for a skipped plan")
	}

	if err := ApplyPlan(client, m, plan); err != nil {
		t.Fatal(err)
	}
	if len(client.sortedTitles) != 0 || len(client.uploadedTitles) != 0 {
		t.Fatalf("expected ApplyPlan to be a no-op for a skipped plan, got uploads=%v sorted=%v", client.uploadedTitles, client.sortedTitles)
	}
}

func TestApplyPlanUploadsAndSkipsReorderWhenAlreadyMatching(t *testing.T) {
	dir := setupFolder(t)
	before := makeTonie([]tonieapi.Chapter{{ID: "c1", Title: "01 - First"}})
	after := makeTonie([]tonieapi.Chapter{{ID: "c1", Title: "01 - First"}, {ID: "c2", Title: "02 - Second"}})
	client := &fakeClient{tonieSequence: []tonieapi.CreativeTonie{before, after}}

	m := Target{TonieID: "t1", Folder: dir, Prune: true}
	plan, err := BuildPlan(client, m)
	if err != nil {
		t.Fatal(err)
	}
	if err := ApplyPlan(client, m, plan); err != nil {
		t.Fatal(err)
	}

	if len(client.uploadedTitles) != 1 || client.uploadedTitles[0] != "02 - Second" {
		t.Fatalf("expected upload of '02 - Second', got %v", client.uploadedTitles)
	}
	if len(client.sortedTitles) != 0 {
		t.Fatalf("expected no sort call since order already matches, got %v", client.sortedTitles)
	}
}

func TestApplyPlanReordersWhenOrderDiffers(t *testing.T) {
	dir := setupFolder(t)
	reversed := makeTonie([]tonieapi.Chapter{{ID: "c2", Title: "02 - Second"}, {ID: "c1", Title: "01 - First"}})
	client := &fakeClient{tonieSequence: []tonieapi.CreativeTonie{reversed, reversed}}

	m := Target{TonieID: "t1", Folder: dir, Prune: true}
	plan, err := BuildPlan(client, m)
	if err != nil {
		t.Fatal(err)
	}
	if err := ApplyPlan(client, m, plan); err != nil {
		t.Fatal(err)
	}

	if len(client.uploadedTitles) != 0 {
		t.Fatalf("expected no uploads, got %v", client.uploadedTitles)
	}
	want := []string{"01 - First", "02 - Second"}
	if !equalStrings(client.sortedTitles, want) {
		t.Fatalf("expected sorted order %v, got %v", want, client.sortedTitles)
	}
}