package playback

import (
	"context"
	"database/sql"
	"encoding/json"
	"io"
	"log/slog"
	"net/http"
	"net/http/httptest"
	"path/filepath"
	"strconv"
	"strings"
	"testing"

	"github.com/mithral/vellum/internal/auth"
	"github.com/mithral/vellum/internal/core"
	"github.com/mithral/vellum/internal/engine"
	"github.com/mithral/vellum/migrations"
)

func testDB(t *testing.T) *sql.DB {
	t.Helper()
	db, err := core.OpenDB(filepath.Join(t.TempDir(), "playback.db"))
	if err != nil {
		t.Fatalf("OpenDB: %v", err)
	}
	t.Cleanup(func() { _ = db.Close() })
	log := slog.New(slog.NewTextHandler(io.Discard, nil))
	if err := core.Migrate(context.Background(), db, migrations.FS, log); err != nil {
		t.Fatalf("Migrate: %v", err)
	}
	return db
}

func mustExec(t *testing.T, db *sql.DB, q string, args ...any) {
	t.Helper()
	if _, err := db.ExecContext(context.Background(), q, args...); err != nil {
		t.Fatalf("exec %q: %v", q, err)
	}
}

func mustID(t *testing.T, db *sql.DB, q string, args ...any) int64 {
	t.Helper()
	var id int64
	if err := db.QueryRowContext(context.Background(), q, args...).Scan(&id); err != nil {
		t.Fatalf("query %q: %v", q, err)
	}
	return id
}

func newHandlers(t *testing.T, db *sql.DB) *Handlers {
	t.Helper()
	log := slog.New(slog.NewTextHandler(io.Discard, nil))
	a := auth.NewAuthenticator(db, "vellum_session", 0, false, log)
	return NewHandlers(db, log, a)
}

// fixture builds two libraries with one item each and a user granted only the
// first. The item in the second library must be invisible.
type fixture struct {
	db    *sql.DB
	libA  int64
	libB  int64
	userA int64
	itemA int64 // mp4 h264 aac, readable
	itemB int64 // mp4 hevc aac, NOT readable
}

func setup(t *testing.T) fixture {
	t.Helper()
	db := testDB(t)
	f := fixture{db: db}
	f.libA = mustID(t, db, `INSERT INTO libraries (name, kind, root_path) VALUES ('A','video','/a') RETURNING id`)
	f.libB = mustID(t, db, `INSERT INTO libraries (name, kind, root_path) VALUES ('B','video','/b') RETURNING id`)
	f.userA = mustID(t, db, `INSERT INTO users (username, password_hash) VALUES ('alice','x') RETURNING id`)
	mustExec(t, db, `INSERT INTO library_grants (user_id, library_id, can_read, can_download) VALUES (?, ?, 1, 1)`, f.userA, f.libA)

	f.itemA = mustID(t, db, `INSERT INTO media_items (library_id, kind, path, title) VALUES (?, 'video', 'a.mp4', 'A') RETURNING id`, f.libA)
	mustExec(t, db, `INSERT INTO media_files (item_id, path, size, container, vcodec, acodec) VALUES (?, 'a.mp4', 1, 'mp4', 'h264', 'aac')`, f.itemA)

	f.itemB = mustID(t, db, `INSERT INTO media_items (library_id, kind, path, title) VALUES (?, 'video', 'b.mp4', 'B') RETURNING id`, f.libB)
	mustExec(t, db, `INSERT INTO media_files (item_id, path, size, container, vcodec, acodec) VALUES (?, 'b.mp4', 1, 'mp4', 'hevc', 'aac')`, f.itemB)
	return f
}

func resolve(t *testing.T, h *Handlers, u auth.User, body string) (int, engine.Resolution) {
	t.Helper()
	req := httptest.NewRequest(http.MethodPost, "/api/v1/playback/resolve", strings.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	rec := httptest.NewRecorder()
	h.handleResolve(rec, req, u)
	var res engine.Resolution
	if rec.Code == http.StatusOK {
		if err := json.Unmarshal(rec.Body.Bytes(), &res); err != nil {
			t.Fatalf("decode resolution: %v (body %s)", err, rec.Body.String())
		}
	}
	return rec.Code, res
}

func TestEnginesEndpoint(t *testing.T) {
	f := setup(t)
	h := newHandlers(t, f.db)

	req := httptest.NewRequest(http.MethodGet, "/api/v1/playback/engines", nil)
	rec := httptest.NewRecorder()
	h.handleEngines(rec, req, auth.User{ID: f.userA})
	if rec.Code != http.StatusOK {
		t.Fatalf("status = %d, body %s", rec.Code, rec.Body.String())
	}
	var body struct {
		Engines []engine.Engine `json:"engines"`
	}
	if err := json.Unmarshal(rec.Body.Bytes(), &body); err != nil {
		t.Fatalf("decode engines: %v", err)
	}
	got := map[string]bool{}
	for _, e := range body.Engines {
		got[e.ID] = true
	}
	for _, id := range []string{"html5", "mpv", "vlc", "mdk"} {
		if !got[id] {
			t.Errorf("engines response is missing %q: %s", id, rec.Body.String())
		}
	}
}

func TestResolvePlayableAndNot(t *testing.T) {
	f := setup(t)
	h := newHandlers(t, f.db)
	u := auth.User{ID: f.userA}

	code, res := resolve(t, h, u, `{"item_id":`+itoa(f.itemA)+`,"engines":["html5"]}`)
	if code != http.StatusOK || !res.Playable || res.Engine == nil || *res.Engine != "html5" {
		t.Fatalf("h264 resolve = %d %+v, want playable html5", code, res)
	}

	// The readable item's facts are h264, so to test HEVC we point at itemB but
	// grant it first — scoping is tested separately.
	mustExec(t, f.db, `INSERT INTO library_grants (user_id, library_id, can_read, can_download) VALUES (?, ?, 1, 1)`, f.userA, f.libB)
	code, res = resolve(t, h, u, `{"item_id":`+itoa(f.itemB)+`,"engines":["html5"]}`)
	if code != http.StatusOK || res.Playable {
		t.Fatalf("hevc resolve = %d %+v, want not playable", code, res)
	}
	if res.Reason != "vcodec:hevc" {
		t.Errorf("reason = %q, want vcodec:hevc", res.Reason)
	}
	if !strings.Contains(res.Message, "HEVC") {
		t.Errorf("message = %q, want it to name HEVC", res.Message)
	}

	// A native engine changes the answer.
	code, res = resolve(t, h, u, `{"item_id":`+itoa(f.itemB)+`,"engines":["html5","mpv"]}`)
	if code != http.StatusOK || !res.Playable || res.Engine == nil || *res.Engine != "mpv" {
		t.Fatalf("hevc+mpv resolve = %d %+v, want playable mpv", code, res)
	}
}

// TestResolveGrantScoping pins the chokepoint: an item in a library the caller
// cannot read must be a 404, indistinguishable from a missing item.
func TestResolveGrantScoping(t *testing.T) {
	f := setup(t)
	h := newHandlers(t, f.db)

	// userA may read libA only; itemB lives in libB.
	code, _ := resolve(t, h, auth.User{ID: f.userA}, `{"item_id":`+itoa(f.itemB)+`,"engines":["html5"]}`)
	if code != http.StatusNotFound {
		t.Errorf("inaccessible item status = %d, want 404", code)
	}

	// A user with no grants gets the same 404 for a readable-by-someone item.
	none := mustID(t, f.db, `INSERT INTO users (username, password_hash) VALUES ('carol','x') RETURNING id`)
	code, _ = resolve(t, h, auth.User{ID: none}, `{"item_id":`+itoa(f.itemA)+`,"engines":["html5"]}`)
	if code != http.StatusNotFound {
		t.Errorf("no-grant item status = %d, want 404", code)
	}

	// A nonexistent item is also a 404, not a leak.
	code, _ = resolve(t, h, auth.User{ID: f.userA}, `{"item_id":99999,"engines":["html5"]}`)
	if code != http.StatusNotFound {
		t.Errorf("missing item status = %d, want 404", code)
	}
}

func TestResolveValidation(t *testing.T) {
	f := setup(t)
	h := newHandlers(t, f.db)
	u := auth.User{ID: f.userA}

	for _, body := range []string{
		`{"item_id":0,"engines":["html5"]}`,
		`{"item_id":-3,"engines":["html5"]}`,
	} {
		if code, _ := resolve(t, h, u, body); code != http.StatusBadRequest {
			t.Errorf("body %s status = %d, want 400", body, code)
		}
	}

	// Missing engines is allowed: the handler falls back to the html5 baseline.
	if code, res := resolve(t, h, u, `{"item_id":`+itoa(f.itemA)+`}`); code != http.StatusOK || !res.Playable {
		t.Errorf("missing engines = %d %+v, want playable fallback", code, res)
	}
}

// TestRegisterRequiresAuth proves the routes are mounted behind the auth
// middleware: an unauthenticated request is rejected with 401.
func TestRegisterRequiresAuth(t *testing.T) {
	f := setup(t)
	h := newHandlers(t, f.db)
	mux := http.NewServeMux()
	h.Register(mux)

	for _, tc := range []struct{ method, path, body string }{
		{http.MethodGet, "/api/v1/playback/engines", ""},
		{http.MethodPost, "/api/v1/playback/resolve", `{"item_id":1,"engines":["html5"]}`},
	} {
		req := httptest.NewRequest(tc.method, tc.path, strings.NewReader(tc.body))
		if tc.body != "" {
			req.Header.Set("Content-Type", "application/json")
		}
		rec := httptest.NewRecorder()
		mux.ServeHTTP(rec, req)
		if rec.Code != http.StatusUnauthorized {
			t.Errorf("%s %s status = %d, want 401", tc.method, tc.path, rec.Code)
		}
	}
}

func itoa(n int64) string { return strconv.FormatInt(n, 10) }