package web

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

	"antidrift/internal/settings"
)

// fakeApplier records the last settings it was asked to apply and can be told to
// reject with ErrInvalidBackend.
type fakeApplier struct {
	called int
	last   settings.Settings
	reject bool
}

func (f *fakeApplier) apply(s settings.Settings) error {
	if f.reject {
		return settings.ErrInvalidBackend
	}
	f.called++
	f.last = s
	return nil
}

func TestGetSettingsReturnsCurrent(t *testing.T) {
	s := newTestServer(t)
	cur := settings.Settings{AIBackend: "claude", MarvinCmd: "am", KnowledgePath: "/tmp/k.md"}
	fa := &fakeApplier{}
	s.SetSettings(filepath.Join(t.TempDir(), "settings.json"), cur, fa.apply)
	r := s.Router()

	req := httptest.NewRequest(http.MethodGet, "/settings", nil)
	w := httptest.NewRecorder()
	r.ServeHTTP(w, req)
	if w.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200", w.Code)
	}
	var got settings.Settings
	if err := json.Unmarshal(w.Body.Bytes(), &got); err != nil {
		t.Fatalf("decode: %v", err)
	}
	if got != cur {
		t.Errorf("got %+v, want %+v", got, cur)
	}
}

func TestPostSettingsValidAppliesAndSaves(t *testing.T) {
	s := newTestServer(t)
	path := filepath.Join(t.TempDir(), "settings.json")
	fa := &fakeApplier{}
	s.SetSettings(path, settings.Settings{}, fa.apply)
	r := s.Router()

	body := `{"ai_backend":"codex","marvin_cmd":"uv run am","knowledge_path":"/tmp/k.md"}`
	w := post(t, r, "/settings", body)
	if w.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200 (body %s)", w.Code, w.Body.String())
	}
	if fa.called != 1 {
		t.Fatalf("applier called %d times, want 1", fa.called)
	}
	if fa.last.AIBackend != "codex" {
		t.Errorf("applied backend = %q, want codex", fa.last.AIBackend)
	}
	saved, err := settings.Load(path)
	if err != nil {
		t.Fatalf("settings file not loadable: %v", err)
	}
	if saved.AIBackend != "codex" || saved.MarvinCmd != "uv run am" || saved.KnowledgePath != "/tmp/k.md" {
		t.Errorf("saved settings = %+v, want codex/uv run am//tmp/k.md", saved)
	}
}

func TestPostSettingsInvalidBackendIs400AndNoSave(t *testing.T) {
	s := newTestServer(t)
	path := filepath.Join(t.TempDir(), "settings.json")
	fa := &fakeApplier{reject: true}
	s.SetSettings(path, settings.Settings{}, fa.apply)
	r := s.Router()

	w := post(t, r, "/settings", `{"ai_backend":"bogus"}`)
	if w.Code != http.StatusBadRequest {
		t.Fatalf("status = %d, want 400", w.Code)
	}
	if _, err := os.Stat(path); !os.IsNotExist(err) {
		t.Errorf("settings file should not exist after rejected save, stat err = %v", err)
	}
	if fa.called != 0 {
		t.Errorf("applier recorded %d successful applies, want 0", fa.called)
	}
}

func TestPostSettingsInvalidJSONIs400(t *testing.T) {
	s := newTestServer(t)
	fa := &fakeApplier{}
	s.SetSettings(filepath.Join(t.TempDir(), "settings.json"), settings.Settings{}, fa.apply)
	r := s.Router()

	w := post(t, r, "/settings", `{not json`)
	if w.Code != http.StatusBadRequest {
		t.Fatalf("status = %d, want 400", w.Code)
	}
	if fa.called != 0 {
		t.Errorf("applier called on invalid json; want 0, got %d", fa.called)
	}
}