package images

import (
	"bytes"
	"encoding/json"
	"mime/multipart"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"gitea.parodia.dev/drwily/petal/internal/auth"
	"gitea.parodia.dev/drwily/petal/internal/db"
)

// a 1x1 transparent PNG.
var pngBytes = []byte{
	0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a, 0x00, 0x00, 0x00, 0x0d, 0x49, 0x48, 0x44, 0x52,
	0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01, 0x08, 0x06, 0x00, 0x00, 0x00, 0x1f, 0x15, 0xc4,
	0x89, 0x00, 0x00, 0x00, 0x0d, 0x49, 0x44, 0x41, 0x54, 0x78, 0x9c, 0x62, 0x00, 0x01, 0x00, 0x00,
	0x05, 0x00, 0x01, 0x0d, 0x0a, 0x2d, 0xb4, 0x00, 0x00, 0x00, 0x00, 0x49, 0x45, 0x4e, 0x44, 0xae,
	0x42, 0x60, 0x82,
}

// another 1x1 PNG, differing in one pixel byte, so it hashes elsewhere.
var otherPNG = append(append([]byte{}, pngBytes[:len(pngBytes)-8]...),
	0x01, 0x00, 0x00, 0x00, 0x49, 0x45, 0x4e, 0x44)

// newStore returns a handler over a fresh directory and database, plus a router
// per user: identical but for who the auth middleware says is calling. Two users
// over one store is the situation that ownership exists to handle.
func newStore(t *testing.T) (dir string, alice, bob http.Handler) {
	t.Helper()
	dir = t.TempDir()
	database, err := db.Open(filepath.Join(t.TempDir(), "test.db"))
	if err != nil {
		t.Fatalf("open db: %v", err)
	}
	t.Cleanup(func() { database.Close() })

	if _, err := database.Exec(
		`INSERT INTO users (id, email, display_name) VALUES (?, ?, ?)`,
		"bob", "bob@petal.local", "Bob",
	); err != nil {
		t.Fatalf("seed second user: %v", err)
	}

	h, err := New(dir, database.DB, db.LocalUserID)
	if err != nil {
		t.Fatalf("new store: %v", err)
	}
	mount := func(userID string) http.Handler {
		return auth.Middleware(auth.StaticResolver(userID))(h.Routes())
	}
	return dir, mount(db.LocalUserID), mount("bob")
}

func uploadReq(t *testing.T, field string, data []byte) *http.Request {
	t.Helper()
	var buf bytes.Buffer
	mw := multipart.NewWriter(&buf)
	fw, err := mw.CreateFormFile(field, "x.png")
	if err != nil {
		t.Fatal(err)
	}
	fw.Write(data)
	mw.Close()
	req := httptest.NewRequest(http.MethodPost, "/", &buf)
	req.Header.Set("Content-Type", mw.FormDataContentType())
	return req
}

// upload posts an image and returns its stored name.
func upload(t *testing.T, h http.Handler, data []byte) string {
	t.Helper()
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, uploadReq(t, "image", data))
	if rec.Code != http.StatusOK {
		t.Fatalf("upload code=%d body=%s", rec.Code, rec.Body)
	}
	var resp struct{ URL string }
	if err := json.Unmarshal(rec.Body.Bytes(), &resp); err != nil {
		t.Fatal(err)
	}
	if !strings.HasPrefix(resp.URL, "/api/images/") || !strings.HasSuffix(resp.URL, ".png") {
		t.Fatalf("unexpected url %q", resp.URL)
	}
	return strings.TrimPrefix(resp.URL, "/api/images/")
}

func get(t *testing.T, h http.Handler, name string) *httptest.ResponseRecorder {
	t.Helper()
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/"+name, nil))
	return rec
}

func TestUploadAndServe(t *testing.T) {
	_, alice, _ := newStore(t)

	name := upload(t, alice, pngBytes)

	// The same content uploaded again dedupes to the same URL.
	if again := upload(t, alice, pngBytes); again != name {
		t.Fatalf("expected dedup to same name, got %q vs %q", again, name)
	}

	rec := get(t, alice, name)
	if rec.Code != http.StatusOK {
		t.Fatalf("serve code=%d", rec.Code)
	}
	if !bytes.Equal(rec.Body.Bytes(), pngBytes) {
		t.Fatal("served bytes differ from uploaded")
	}
}

// The point of the ownership table: a hash is not a capability.
func TestImageIsolation(t *testing.T) {
	_, alice, bob := newStore(t)
	name := upload(t, alice, pngBytes)

	if rec := get(t, bob, name); rec.Code != http.StatusNotFound {
		t.Fatalf("bob fetched alice's image: code=%d", rec.Code)
	}

	// Nor can he delete it out from under her.
	rec := httptest.NewRecorder()
	bob.ServeHTTP(rec, httptest.NewRequest(http.MethodDelete, "/"+name, nil))
	if rec.Code != http.StatusNotFound {
		t.Fatalf("bob deleted alice's image: code=%d", rec.Code)
	}
	if got := get(t, alice, name); got.Code != http.StatusOK {
		t.Fatalf("alice's image disappeared: code=%d", got.Code)
	}
}

// Deduplication has to survive ownership: one file, one row each.
func TestDedupAcrossUsers(t *testing.T) {
	dir, alice, bob := newStore(t)

	name := upload(t, alice, pngBytes)
	if bobName := upload(t, bob, pngBytes); bobName != name {
		t.Fatalf("expected the same stored name, got %q vs %q", bobName, name)
	}

	entries, _ := os.ReadDir(dir)
	if len(entries) != 1 {
		t.Fatalf("expected 1 file on disk, found %d", len(entries))
	}
	for _, h := range []http.Handler{alice, bob} {
		if rec := get(t, h, name); rec.Code != http.StatusOK {
			t.Fatalf("owner could not fetch shared image: code=%d", rec.Code)
		}
	}

	// Alice dropping her copy must not take Bob's picture away with it.
	rec := httptest.NewRecorder()
	alice.ServeHTTP(rec, httptest.NewRequest(http.MethodDelete, "/"+name, nil))
	if rec.Code != http.StatusNoContent {
		t.Fatalf("delete code=%d", rec.Code)
	}
	if got := get(t, alice, name); got.Code != http.StatusNotFound {
		t.Fatalf("alice still sees a deleted image: code=%d", got.Code)
	}
	if got := get(t, bob, name); got.Code != http.StatusOK {
		t.Fatalf("bob lost his image when alice deleted hers: code=%d", got.Code)
	}
	if _, err := os.Stat(filepath.Join(dir, name)); err != nil {
		t.Fatalf("file removed while still owned: %v", err)
	}

	// The last owner leaving takes the file with them.
	rec2 := httptest.NewRecorder()
	bob.ServeHTTP(rec2, httptest.NewRequest(http.MethodDelete, "/"+name, nil))
	if rec2.Code != http.StatusNoContent {
		t.Fatalf("delete code=%d", rec2.Code)
	}
	if _, err := os.Stat(filepath.Join(dir, name)); !os.IsNotExist(err) {
		t.Fatalf("file survived its last owner: %v", err)
	}
}

// Images that predate ownership must not vanish from documents that use them.
func TestBackfillClaimsExistingFiles(t *testing.T) {
	dir := t.TempDir()
	database, err := db.Open(filepath.Join(t.TempDir(), "test.db"))
	if err != nil {
		t.Fatalf("open db: %v", err)
	}
	defer database.Close()

	orphan := "deadbeefdeadbeefdeadbeefdeadbeef.png"
	if err := os.WriteFile(filepath.Join(dir, orphan), pngBytes, 0o644); err != nil {
		t.Fatal(err)
	}

	h, err := New(dir, database.DB, db.LocalUserID)
	if err != nil {
		t.Fatalf("new store: %v", err)
	}
	alice := auth.Middleware(auth.StaticResolver(db.LocalUserID))(h.Routes())
	if rec := get(t, alice, orphan); rec.Code != http.StatusOK {
		t.Fatalf("pre-existing image not claimed: code=%d", rec.Code)
	}

	// Re-running the backfill (i.e. a restart) must not double up or reassign.
	if _, err := New(dir, database.DB, "bob"); err != nil {
		t.Fatalf("second backfill: %v", err)
	}

	// And an owner who no longer exists — which is what the `local` account
	// becomes once it has been migrated onto a real one — must be skipped, not
	// turned into a foreign-key error that takes startup down with it.
	if _, err := New(dir, database.DB, "nobody-at-all"); err != nil {
		t.Fatalf("backfill for a missing owner should be a no-op, got: %v", err)
	}
	var owners int
	if err := database.QueryRow(`SELECT COUNT(*) FROM images WHERE name = ?`, orphan).Scan(&owners); err != nil {
		t.Fatal(err)
	}
	if owners != 1 {
		t.Fatalf("expected the backfill to be idempotent, got %d owners", owners)
	}
}

func TestUploadRejectsNonImage(t *testing.T) {
	_, alice, _ := newStore(t)
	rec := httptest.NewRecorder()
	alice.ServeHTTP(rec, uploadReq(t, "image", []byte("this is plainly not an image at all")))
	if rec.Code != http.StatusUnsupportedMediaType {
		t.Fatalf("expected 415, got %d", rec.Code)
	}
}

func TestServeMissing(t *testing.T) {
	_, alice, _ := newStore(t)
	if rec := get(t, alice, "deadbeef.png"); rec.Code != http.StatusNotFound {
		t.Fatalf("expected 404, got %d", rec.Code)
	}
}