package media

import (
	"database/sql"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"testing"

	"github.com/mithral/vellum/internal/auth"
	"github.com/mithral/vellum/internal/transcode"
)

// fakeSessions stands in for *transcode.Manager: it records Start calls and
// hands back a session rooted at a directory the test controls, with no
// hardware and no ffmpeg anywhere.
type fakeSessions struct {
	dir      string
	startErr error
	starts   int
}

func (f *fakeSessions) Start(itemID int64, inputPath, cacheDir string) (transcode.Session, error) {
	f.starts++
	if f.startErr != nil {
		return nil, f.startErr
	}
	return fakeSession{dir: f.dir}, nil
}

type fakeSession struct{ dir string }

func (s fakeSession) PlaylistPath() string { return filepath.Join(s.dir, "playlist.m3u8") }
func (s fakeSession) Dir() string          { return s.dir }
func (s fakeSession) Close() error         { return nil }

// transcodeFixture is a readable video item, an item in a library the caller may
// not read, and a granted user.
type transcodeFixture struct {
	h         *Handlers
	db        *sql.DB
	base      string
	fake      *fakeSessions
	user      int64
	item      int64
	forbidden int64
}

func newTranscodeFixture(t *testing.T) transcodeFixture {
	t.Helper()
	db := testDB(t)
	lib := newLibrary(t, db, "Video", "video", t.TempDir())
	other := newLibrary(t, db, "Other", "video", t.TempDir())

	// The session dir sits two levels below base, so "../../etc/passwd" from it
	// resolves to base/etc/passwd — a file a traversal test can actually create.
	base := t.TempDir()
	dir := filepath.Join(base, "transcode", "1-1")
	if err := os.MkdirAll(dir, 0o755); err != nil {
		t.Fatalf("mkdir session: %v", err)
	}

	f := transcodeFixture{db: db, base: base, fake: &fakeSessions{dir: dir}}
	f.user = newUser(t, db, "watcher")
	grantRead(t, db, f.user, lib)

	const at = "2026-01-01T00:00:00.000Z"
	f.item = newItem(t, db, lib, "video", "movie.mkv", "Movie", "movie", false, at)
	f.forbidden = newItem(t, db, other, "video", "secret.mkv", "Secret", "secret", false, at)

	f.h = mediaHandlers(t, db)
	f.h.sessions = f.fake
	return f
}

func getPlaylist(t *testing.T, h *Handlers, u auth.User, itemID int64) *httptest.ResponseRecorder {
	t.Helper()
	req := httptest.NewRequest(http.MethodGet, "/api/v1/items/1/transcode/playlist.m3u8", nil)
	req.SetPathValue("id", itoa(itemID))
	rec := httptest.NewRecorder()
	h.handleTranscodePlaylist(rec, req, u)
	return rec
}

func getSegment(t *testing.T, h *Handlers, u auth.User, itemID int64, segment string) *httptest.ResponseRecorder {
	t.Helper()
	req := httptest.NewRequest(http.MethodGet, "/api/v1/items/1/transcode/"+segment, nil)
	req.SetPathValue("id", itoa(itemID))
	req.SetPathValue("segment", segment)
	rec := httptest.NewRecorder()
	h.handleTranscodeSegment(rec, req, u)
	return rec
}

// TestTranscodePlaylistStartsAndServes pins the lazy start: the request begins
// the session and returns the playlist bytes exactly as they are on disk.
func TestTranscodePlaylistStartsAndServes(t *testing.T) {
	f := newTranscodeFixture(t)
	const playlist = "#EXTM3U\n#EXT-X-VERSION:3\n#EXTINF:6.0,\nseg00001.ts\n"
	if err := os.WriteFile(filepath.Join(f.fake.dir, "playlist.m3u8"), []byte(playlist), 0o640); err != nil {
		t.Fatalf("write playlist: %v", err)
	}

	rec := getPlaylist(t, f.h, auth.User{ID: f.user}, f.item)
	if rec.Code != http.StatusOK {
		t.Fatalf("status = %d, body=%s", rec.Code, rec.Body.String())
	}
	if ct := rec.Header().Get("Content-Type"); ct != "application/vnd.apple.mpegurl" {
		t.Errorf("content-type = %q, want application/vnd.apple.mpegurl", ct)
	}
	if got := rec.Body.String(); got != playlist {
		t.Errorf("body = %q, want %q", got, playlist)
	}
	if f.fake.starts != 1 {
		t.Errorf("Start calls = %d, want 1", f.fake.starts)
	}

	// A second request touches the session again, so the idle reaper leaves a
	// stream being watched alone.
	_ = getPlaylist(t, f.h, auth.User{ID: f.user}, f.item)
	if f.fake.starts != 2 {
		t.Errorf("Start calls after second request = %d, want 2", f.fake.starts)
	}
}

// TestTranscodeSegmentServedAndTraversalRefused pins the segment name check: the
// exact shape ffmpeg writes is served, and everything else — a traversal above
// all — is a 404.
func TestTranscodeSegmentServedAndTraversalRefused(t *testing.T) {
	f := newTranscodeFixture(t)
	const segment = "\x47@\x00\x10payload"
	if err := os.WriteFile(filepath.Join(f.fake.dir, "seg00001.ts"), []byte(segment), 0o640); err != nil {
		t.Fatalf("write segment: %v", err)
	}

	rec := getSegment(t, f.h, auth.User{ID: f.user}, f.item, "seg00001.ts")
	if rec.Code != http.StatusOK {
		t.Fatalf("valid segment status = %d, body=%s", rec.Code, rec.Body.String())
	}
	if ct := rec.Header().Get("Content-Type"); ct != "video/mp2t" {
		t.Errorf("content-type = %q, want video/mp2t", ct)
	}
	if got := rec.Body.String(); got != segment {
		t.Errorf("body = %q, want %q", got, segment)
	}

	for _, name := range []string{
		"../../etc/passwd",
		"..%2f..%2fetc%2fpasswd",
		"seg1.ts",
		"seg0001.ts",
		"seg000001.ts",
		"seg00001.ts.bak",
		"playlist.m3u8",
		"",
	} {
		if rec := getSegment(t, f.h, auth.User{ID: f.user}, f.item, name); rec.Code != http.StatusNotFound {
			t.Errorf("segment %q status = %d, want 404", name, rec.Code)
		}
	}
}

// TestTranscodeSegmentTraversalCannotEscapeOnce pins the traversal case with a
// file that genuinely exists at the joined path: without the name check the
// handler would serve it, so a green run proves the check is load-bearing.
func TestTranscodeSegmentTraversalCannotEscapeOnce(t *testing.T) {
	f := newTranscodeFixture(t)
	if err := os.MkdirAll(filepath.Join(f.base, "etc"), 0o755); err != nil {
		t.Fatalf("mkdir etc: %v", err)
	}
	if err := os.WriteFile(filepath.Join(f.base, "etc", "passwd"), []byte("SECRET"), 0o640); err != nil {
		t.Fatalf("write passwd: %v", err)
	}

	rec := getSegment(t, f.h, auth.User{ID: f.user}, f.item, "../../etc/passwd")
	if rec.Code != http.StatusNotFound {
		t.Fatalf("traversal status = %d, want 404 (body=%s)", rec.Code, rec.Body.String())
	}
	if rec.Body.String() == "SECRET" {
		t.Fatal("traversal served a file outside the session directory")
	}
}

// TestTranscodeRoutesAreGrantScoped pins the access chokepoint on both routes:
// an item in a library the caller cannot read answers with the same 404, byte
// for byte, as an item that does not exist — and does not start an encoder.
func TestTranscodeRoutesAreGrantScoped(t *testing.T) {
	f := newTranscodeFixture(t)
	u := auth.User{ID: f.user}

	fb := getPlaylist(t, f.h, u, f.forbidden)
	ab := getPlaylist(t, f.h, u, 999999)
	if fb.Code != http.StatusNotFound || ab.Code != http.StatusNotFound {
		t.Fatalf("playlist statuses = %d/%d, want 404/404", fb.Code, ab.Code)
	}
	if fb.Body.String() != ab.Body.String() {
		t.Errorf("playlist forbidden body %q != absent body %q", fb.Body.String(), ab.Body.String())
	}

	fs := getSegment(t, f.h, u, f.forbidden, "seg00001.ts")
	as := getSegment(t, f.h, u, 999999, "seg00001.ts")
	if fs.Code != http.StatusNotFound || as.Code != http.StatusNotFound {
		t.Fatalf("segment statuses = %d/%d, want 404/404", fs.Code, as.Code)
	}
	if fs.Body.String() != as.Body.String() {
		t.Errorf("segment forbidden body %q != absent body %q", fs.Body.String(), as.Body.String())
	}

	// The item is rejected before Start, so a forbidden request never pins the
	// GPU.
	if f.fake.starts != 0 {
		t.Errorf("Start calls on forbidden requests = %d, want 0", f.fake.starts)
	}

	none := getPlaylist(t, f.h, auth.User{ID: newUser(t, f.db, "nobody")}, f.item)
	if none.Code != http.StatusNotFound {
		t.Errorf("no-grant status = %d, want 404", none.Code)
	}
}

// TestTranscodeRefusalsAreNot500 pins that a host with no encoder and a full
// server both get a clear 503 rather than a 500.
func TestTranscodeRefusalsAreNot500(t *testing.T) {
	for _, err := range []error{transcode.ErrUnavailable, transcode.ErrAtCapacity, transcode.ErrShutdown} {
		f := newTranscodeFixture(t)
		f.fake.startErr = err

		rec := getPlaylist(t, f.h, auth.User{ID: f.user}, f.item)
		if rec.Code != http.StatusServiceUnavailable {
			t.Errorf("start error %v status = %d, want 503", err, rec.Code)
		}
	}
}