package spell

import (
	"bytes"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"path/filepath"
	"testing"

	"github.com/go-chi/chi/v5"

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

// newTestServer mounts the routes behind the same auth middleware main.go
// installs — a bare router resolves no caller, so every scoped query would
// silently match nothing.
func newTestServer(t *testing.T) (http.Handler, *db.DB) {
	t.Helper()
	database, err := db.Open(filepath.Join(t.TempDir(), "test.db"))
	if err != nil {
		t.Fatalf("open db: %v", err)
	}
	t.Cleanup(func() { database.Close() })
	r := chi.NewRouter()
	r.Mount("/spell", New(database).Routes())
	return auth.Middleware(auth.StaticResolver(db.LocalUserID))(r), database
}

func do(t *testing.T, srv http.Handler, method, path, body string) *httptest.ResponseRecorder {
	t.Helper()
	var r *http.Request
	if body != "" {
		r = httptest.NewRequest(method, path, bytes.NewBufferString(body))
	} else {
		r = httptest.NewRequest(method, path, nil)
	}
	rec := httptest.NewRecorder()
	srv.ServeHTTP(rec, r)
	return rec
}

func decodeWords(t *testing.T, rec *httptest.ResponseRecorder) wordsResponse {
	t.Helper()
	if rec.Code != http.StatusOK {
		t.Fatalf("code=%d body=%s", rec.Code, rec.Body)
	}
	var got wordsResponse
	if err := json.Unmarshal(rec.Body.Bytes(), &got); err != nil {
		t.Fatalf("decode: %v (body %s)", err, rec.Body)
	}
	return got
}

func equal(a, b []string) bool {
	if len(a) != len(b) {
		return false
	}
	for i := range a {
		if a[i] != b[i] {
			return false
		}
	}
	return true
}

// TestLifecycle walks add → list → re-add → delete, and asserts the two
// properties the client relies on: adds are idempotent, and every response
// carries the full resulting list so the browser never has to merge.
func TestLifecycle(t *testing.T) {
	srv, _ := newTestServer(t)

	// Empty to start, and a list, never null.
	got := decodeWords(t, do(t, srv, http.MethodGet, "/spell/words", ""))
	if got.Lang != "en" || len(got.Words) != 0 {
		t.Fatalf("fresh list = %+v, want empty en", got)
	}
	if !bytes.Contains(
		do(t, srv, http.MethodGet, "/spell/words", "").Body.Bytes(), []byte(`"words":[]`),
	) {
		t.Fatal("empty list encoded as null, not []")
	}

	// One word, then a bulk add (the shape the browser's one-time adoption uses).
	got = decodeWords(t, do(t, srv, http.MethodPost, "/spell/words", `{"word":"Petal"}`))
	if !equal(got.Words, []string{"Petal"}) {
		t.Fatalf("after add = %v", got.Words)
	}
	got = decodeWords(t, do(t, srv, http.MethodPost, "/spell/words",
		`{"words":["hanfu","qipao","Petal"]}`))
	if !equal(got.Words, []string{"Petal", "hanfu", "qipao"}) {
		t.Fatalf("after bulk add = %v, want sorted and de-duplicated", got.Words)
	}

	// Re-adding an existing word must not error or duplicate it.
	got = decodeWords(t, do(t, srv, http.MethodPost, "/spell/words", `{"word":"hanfu"}`))
	if !equal(got.Words, []string{"Petal", "hanfu", "qipao"}) {
		t.Fatalf("re-add changed the list: %v", got.Words)
	}

	// Delete, then delete again — forgetting a word Petal never knew is a
	// success, since the caller's intent already holds.
	got = decodeWords(t, do(t, srv, http.MethodDelete, "/spell/words?word=qipao", ""))
	if !equal(got.Words, []string{"Petal", "hanfu"}) {
		t.Fatalf("after delete = %v", got.Words)
	}
	got = decodeWords(t, do(t, srv, http.MethodDelete, "/spell/words?word=qipao", ""))
	if !equal(got.Words, []string{"Petal", "hanfu"}) {
		t.Fatalf("repeat delete = %v", got.Words)
	}
}

// TestLanguagesDoNotMerge is the reason `lang` is in the primary key: a word the
// writer excused in English must not silence the pt-PT dictionary too.
func TestLanguagesDoNotMerge(t *testing.T) {
	srv, _ := newTestServer(t)

	do(t, srv, http.MethodPost, "/spell/words", `{"word":"tarde"}`)
	got := decodeWords(t, do(t, srv, http.MethodPost, "/spell/words",
		`{"lang":"pt-PT","word":"tarde"}`))
	if !equal(got.Words, []string{"tarde"}) || got.Lang != "pt-pt" {
		t.Fatalf("pt list = %+v", got)
	}

	// Removing it from one dictionary leaves the other alone.
	do(t, srv, http.MethodDelete, "/spell/words?lang=pt-PT&word=tarde", "")
	if got = decodeWords(t, do(t, srv, http.MethodGet, "/spell/words?lang=pt-PT", "")); len(got.Words) != 0 {
		t.Fatalf("pt list after delete = %v", got.Words)
	}
	if got = decodeWords(t, do(t, srv, http.MethodGet, "/spell/words", "")); !equal(got.Words, []string{"tarde"}) {
		t.Fatalf("en list collaterally damaged: %v", got.Words)
	}

	// Case and whitespace in the tag must not split one list into three.
	got = decodeWords(t, do(t, srv, http.MethodGet, "/spell/words?lang=EN", ""))
	if !equal(got.Words, []string{"tarde"}) {
		t.Fatalf("uppercase lang tag saw a different list: %v", got.Words)
	}
}

func TestRejectsJunk(t *testing.T) {
	srv, _ := newTestServer(t)

	cases := []struct{ name, method, path, body string }{
		{"empty word", http.MethodPost, "/spell/words", `{"word":"  "}`},
		{"no word at all", http.MethodPost, "/spell/words", `{"lang":"en"}`},
		{"not json", http.MethodPost, "/spell/words", `nonsense`},
		{"delete without a word", http.MethodDelete, "/spell/words", ""},
	}
	for _, c := range cases {
		if rec := do(t, srv, c.method, c.path, c.body); rec.Code != http.StatusBadRequest {
			t.Errorf("%s: code=%d, want 400", c.name, rec.Code)
		}
	}

	// An over-long entry is dropped rather than stored — a pasted paragraph is
	// not a word. Dropping the only entry leaves nothing to add, hence 400.
	long := `{"word":"` + string(bytes.Repeat([]byte("a"), MaxWordLen+1)) + `"}`
	if rec := do(t, srv, http.MethodPost, "/spell/words", long); rec.Code != http.StatusBadRequest {
		t.Errorf("over-long word: code=%d, want 400", rec.Code)
	}
}

// TestTwoUsersDoNotShare is the standing rule for every user-scoped endpoint:
// mount the same routes twice behind two resolvers over one database.
func TestTwoUsersDoNotShare(t *testing.T) {
	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)
	}
	mount := func(userID string) http.Handler {
		r := chi.NewRouter()
		r.Mount("/spell", New(database).Routes())
		return auth.Middleware(auth.StaticResolver(userID))(r)
	}
	alice, bob := mount(db.LocalUserID), mount("bob")

	do(t, alice, http.MethodPost, "/spell/words", `{"words":["Xiaolan","hanfu"]}`)

	// Bob sees none of it — a personal dictionary is built from private writing.
	if got := decodeWords(t, do(t, bob, http.MethodGet, "/spell/words", "")); len(got.Words) != 0 {
		t.Fatalf("bob sees alice's words: %v", got.Words)
	}

	// Bob's own identical word is his own row, and deleting it leaves hers.
	do(t, bob, http.MethodPost, "/spell/words", `{"word":"hanfu"}`)
	do(t, bob, http.MethodDelete, "/spell/words?word=hanfu", "")
	if got := decodeWords(t, do(t, alice, http.MethodGet, "/spell/words", "")); !equal(got.Words, []string{"Xiaolan", "hanfu"}) {
		t.Fatalf("bob's delete reached alice's list: %v", got.Words)
	}

	// Deleting the account takes the dictionary with it.
	if _, err := database.Exec(`DELETE FROM users WHERE id = 'bob'`); err != nil {
		t.Fatalf("delete user: %v", err)
	}
	var n int
	if err := database.QueryRow(
		`SELECT COUNT(*) FROM personal_words WHERE user_id = 'bob'`).Scan(&n); err != nil {
		t.Fatalf("count: %v", err)
	}
	if n != 0 {
		t.Fatalf("%d orphaned rows after the user was deleted", n)
	}
}