package recognize

import (
	"context"
	"errors"
	"io"
	"log/slog"
	"strings"
	"testing"

	"git.vakhrushev.me/av/jellybit/internal/llm"
)

// fakeLLM отдаёт заранее заданные ответы/ошибки по порядку вызовов.
type fakeLLM struct {
	responses []string
	errs      []error
	calls     int
	lastReq   llm.Request
}

func (f *fakeLLM) Complete(_ context.Context, req llm.Request) (llm.Response, error) {
	f.lastReq = req
	i := f.calls
	f.calls++
	if i < len(f.errs) && f.errs[i] != nil {
		return llm.Response{}, f.errs[i]
	}
	content := ""
	switch {
	case i < len(f.responses):
		content = f.responses[i]
	case len(f.responses) > 0:
		content = f.responses[len(f.responses)-1]
	}
	return llm.Response{Content: content}, nil
}

func testLogger() *slog.Logger {
	return slog.New(slog.NewTextHandler(io.Discard, nil))
}

func TestRecognize_Movie(t *testing.T) {
	in := Input{
		Name:    "The.Matrix.1999.1080p.BluRay.x264",
		Context: "научная фантастика",
		Files: []File{
			{Path: "The.Matrix.1999/movie.mkv", Size: 8 << 30},
			{Path: "The.Matrix.1999/sample.mkv", Size: 50 << 20},
		},
	}
	resp := `{"type":"movie","title":"The Matrix","original_title":"","year":1999,
		"provider_hint":"The Matrix 1999","confidence":0.9,"notes":"",
		"files":[
			{"src":"The.Matrix.1999/movie.mkv","role":"main","season":null,"episode":null},
			{"src":"The.Matrix.1999/sample.mkv","role":"sample","season":null,"episode":null}
		]}`
	f := &fakeLLM{responses: []string{resp}}
	r := New(f, nil, Config{MaxRetries: 2}, testLogger())

	res, err := r.Recognize(context.Background(), in)
	if err != nil {
		t.Fatalf("Recognize: %v", err)
	}
	if res.Plan.Type != MediaMovie || res.Plan.Title != "The Matrix" || res.Plan.Year != 1999 {
		t.Errorf("plan = %+v", res.Plan)
	}
	if res.Attempts != 1 {
		t.Errorf("attempts = %d, want 1", res.Attempts)
	}
	if res.Decision.Auto {
		t.Error("auto must be false in Ф2 (no DB match)")
	}
	if len(res.Decision.Reasons) == 0 {
		t.Error("expected at least the no-DB-match reason")
	}
	// Чистая структура + уверенность 0.9 ≥ порога: единственная причина —
	// отсутствие матча в базе.
	if len(res.Decision.Reasons) != 1 || !hasReason(res.Decision.Reasons, "метабазы отключены") {
		t.Errorf("unexpected reasons: %v", res.Decision.Reasons)
	}
}

func TestRecognize_Series(t *testing.T) {
	in := Input{
		Name: "Avatar.The.Last.Airbender.Book.2",
		Files: []File{
			{Path: "Avatar/01.mkv", Size: 200 << 20},
			{Path: "Avatar/02.mkv", Size: 200 << 20},
			{Path: "Avatar/03.mkv", Size: 200 << 20},
		},
	}
	resp := `{"type":"series","title":"Avatar: The Last Airbender","year":2006,
		"confidence":0.8,"files":[
			{"src":"Avatar/01.mkv","role":"episode","season":2,"episode":1},
			{"src":"Avatar/02.mkv","role":"episode","season":2,"episode":2},
			{"src":"Avatar/03.mkv","role":"episode","season":2,"episode":3}
		]}`
	f := &fakeLLM{responses: []string{resp}}
	r := New(f, nil, Config{}, testLogger())

	res, err := r.Recognize(context.Background(), in)
	if err != nil {
		t.Fatalf("Recognize: %v", err)
	}
	if res.Plan.Type != MediaSeries || len(res.Plan.Files) != 3 {
		t.Errorf("plan = %+v", res.Plan)
	}
	// Метабазы выключены → авто нет; причина про базу обязательна.
	if res.Decision.Auto {
		t.Error("auto must be false without metadata providers")
	}
	if !hasReason(res.Decision.Reasons, "метабазы отключены") {
		t.Errorf("expected metadata-off reason, got: %v", res.Decision.Reasons)
	}
}

func hasReason(reasons []string, substr string) bool {
	for _, r := range reasons {
		if strings.Contains(r, substr) {
			return true
		}
	}
	return false
}

func TestRecognize_RetriesOnBadSrcThenSucceeds(t *testing.T) {
	in := Input{
		Name:  "Some.Movie.2020",
		Files: []File{{Path: "movie/film.mkv", Size: 4 << 30}},
	}
	bad := `{"type":"movie","title":"Some Movie","files":[
		{"src":"movie/WRONG.mkv","role":"main"}]}`
	good := `{"type":"movie","title":"Some Movie","year":2020,"files":[
		{"src":"movie/film.mkv","role":"main"}]}`
	f := &fakeLLM{responses: []string{bad, good}}
	r := New(f, nil, Config{MaxRetries: 2}, testLogger())

	res, err := r.Recognize(context.Background(), in)
	if err != nil {
		t.Fatalf("Recognize: %v", err)
	}
	if res.Attempts != 2 {
		t.Errorf("attempts = %d, want 2", res.Attempts)
	}
	if res.Plan.Title != "Some Movie" {
		t.Errorf("plan = %+v", res.Plan)
	}
	// Корректирующее сообщение должно содержать схему и список файлов.
	last := f.lastReq.Messages[len(f.lastReq.Messages)-1]
	if !strings.Contains(last.Content, "Ответ не принят") || !strings.Contains(last.Content, "film.mkv") {
		t.Errorf("correction message missing context: %q", last.Content)
	}
}

func TestRecognize_ExhaustedRetriesGoesToReview(t *testing.T) {
	in := Input{Name: "x", Files: []File{{Path: "a.mkv", Size: 1}}}
	bad := `not a json at all`
	f := &fakeLLM{responses: []string{bad}}
	r := New(f, nil, Config{MaxRetries: 2}, testLogger())

	res, err := r.Recognize(context.Background(), in)
	if err != nil {
		t.Fatalf("Recognize should not error on unparsed response: %v", err)
	}
	if f.calls != 3 { // 1 + 2 ретрая
		t.Errorf("calls = %d, want 3", f.calls)
	}
	if res.Decision.Auto || len(res.Decision.Reasons) == 0 {
		t.Errorf("expected review with reason, got %+v", res.Decision)
	}
	if !strings.Contains(res.Decision.Reasons[0], "не разобран") {
		t.Errorf("reason = %q", res.Decision.Reasons[0])
	}
	if res.Raw != bad {
		t.Errorf("raw = %q, want last response", res.Raw)
	}
}

func TestRecognize_TransportErrorPropagates(t *testing.T) {
	in := Input{Name: "x", Files: []File{{Path: "a.mkv", Size: 1}}}
	wantErr := errors.New("connection refused")
	f := &fakeLLM{errs: []error{wantErr}}
	r := New(f, nil, Config{MaxRetries: 2}, testLogger())

	_, err := r.Recognize(context.Background(), in)
	if err == nil || !errors.Is(err, wantErr) {
		t.Fatalf("err = %v, want wrapped %v", err, wantErr)
	}
	if f.calls != 1 {
		t.Errorf("calls = %d, want 1 (transport errors not retried here)", f.calls)
	}
}

func TestRecognize_PromptCarriesSignals(t *testing.T) {
	in := Input{
		Name:    "Some.Show.S01",
		Context: "сериал от HBO",
		Hints:   []string{"это второй сезон", ""},
		Files:   []File{{Path: "ep1.mkv", Size: 1 << 30}},
	}
	resp := `{"type":"series","title":"Some Show","files":[
		{"src":"ep1.mkv","role":"episode","season":1,"episode":1}]}`
	f := &fakeLLM{responses: []string{resp}}
	r := New(f, nil, Config{}, testLogger())
	if _, err := r.Recognize(context.Background(), in); err != nil {
		t.Fatalf("Recognize: %v", err)
	}

	if len(f.lastReq.Messages) != 2 {
		t.Fatalf("want system+user, got %d messages", len(f.lastReq.Messages))
	}
	user := f.lastReq.Messages[1].Content
	for _, want := range []string{"Some.Show.S01", "сериал от HBO", "это второй сезон", "ep1.mkv"} {
		if !strings.Contains(user, want) {
			t.Errorf("user prompt missing %q\n%s", want, user)
		}
	}
	if !f.lastReq.JSONMode {
		t.Error("JSONMode must be set")
	}
}

func TestRecognize_FileListTruncated(t *testing.T) {
	files := make([]File, 250)
	planFiles := make([]string, 0, 250)
	for i := range files {
		files[i] = File{Path: pathOf(i), Size: 100 << 20}
	}
	// План ссылается только на первый файл — этого достаточно для схемы.
	_ = planFiles
	in := Input{Name: "Big.Pack", Files: files}
	resp := `{"type":"series","title":"Big","files":[{"src":"` + pathOf(0) +
		`","role":"episode","season":1,"episode":1}]}`
	f := &fakeLLM{responses: []string{resp}}
	r := New(f, nil, Config{MaxFiles: 100}, testLogger())
	if _, err := r.Recognize(context.Background(), in); err != nil {
		t.Fatalf("Recognize: %v", err)
	}
	user := f.lastReq.Messages[1].Content
	if !strings.Contains(user, "усечён") {
		t.Errorf("expected truncation note in prompt")
	}
	if !strings.Contains(user, "Файлы (250") {
		t.Errorf("expected total count 250 in prompt")
	}
}

func pathOf(i int) string {
	return "show/ep" + itoa(i) + ".mkv"
}