package web_test

import (
	"io"
	"io/fs"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"

	"sourcecraft.dev/bigbes/lethe/internal/server/web"
)

// TestHandler_InjectsConfigIntoIndex asserts that GET / returns 200 HTML
// containing window.__LETHE_CONFIG__ with the supplied values, exactly once.
func TestHandler_InjectsConfigIntoIndex(t *testing.T) {
	h := web.Handler(web.Config{
		Issuer:   "http://stub",
		ClientID: "lethe",
	})

	req := httptest.NewRequest(http.MethodGet, "/", nil)
	rr := httptest.NewRecorder()
	h.ServeHTTP(rr, req)

	resp := rr.Result()
	if resp.StatusCode != http.StatusOK {
		t.Fatalf("status = %d; want 200", resp.StatusCode)
	}

	body, _ := io.ReadAll(resp.Body)
	bodyStr := string(body)

	want := `window.__LETHE_CONFIG__={"Issuer":"http://stub","ClientID":"lethe"}`
	if !strings.Contains(bodyStr, want) {
		t.Errorf("body does not contain %q\nbody (first 500 chars):\n%s", want, truncate(bodyStr, 500))
	}

	// Exactly once.
	count := strings.Count(bodyStr, "__LETHE_CONFIG__")
	if count != 1 {
		t.Errorf("__LETHE_CONFIG__ appears %d times; want 1", count)
	}
}

// TestHandler_AssetsBypassInjection asserts that static asset paths do not
// receive the script injection. We test by checking the response body does
// not contain __LETHE_CONFIG__ — robust against asset filename changes.
func TestHandler_AssetsBypassInjection(t *testing.T) {
	// Discover an asset file from the embedded FS via the handler's fallback
	// behavior, or just verify that a known asset path bypasses injection.
	// We check absence of __LETHE_CONFIG__ in any /assets/ response.
	h := web.Handler(web.Config{
		Issuer:   "http://stub",
		ClientID: "lethe",
	})

	// Find an actual asset file name to request.
	sub, err := web.DistFS()
	if err != nil {
		t.Fatalf("DistFS: %v", err)
	}
	var assetFile string
	_ = fs.WalkDir(sub, "assets", func(path string, d fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if !d.IsDir() && assetFile == "" {
			assetFile = path
		}
		return nil
	})
	if assetFile == "" {
		t.Skip("no asset files found in embedded FS — skip")
	}

	req := httptest.NewRequest(http.MethodGet, "/"+assetFile, nil)
	rr := httptest.NewRecorder()
	h.ServeHTTP(rr, req)

	resp := rr.Result()
	body, _ := io.ReadAll(resp.Body)

	if strings.Contains(string(body), "__LETHE_CONFIG__") {
		t.Errorf("asset %q response contains __LETHE_CONFIG__ — should be bypass", assetFile)
	}
}

// TestHandler_SPAFallbackInjects asserts that an unknown SPA route returns
// 200 HTML with the config injection (SPA fallback returns index.html).
func TestHandler_SPAFallbackInjects(t *testing.T) {
	h := web.Handler(web.Config{
		Issuer:   "http://stub",
		ClientID: "lethe",
	})

	req := httptest.NewRequest(http.MethodGet, "/some/spa/route", nil)
	rr := httptest.NewRecorder()
	h.ServeHTTP(rr, req)

	resp := rr.Result()
	if resp.StatusCode != http.StatusOK {
		t.Fatalf("status = %d; want 200", resp.StatusCode)
	}

	body, _ := io.ReadAll(resp.Body)
	bodyStr := string(body)

	if !strings.Contains(bodyStr, "__LETHE_CONFIG__") {
		t.Errorf("SPA fallback response does not contain __LETHE_CONFIG__\nbody:\n%s", truncate(bodyStr, 500))
	}
}

func truncate(s string, n int) string {
	if len(s) <= n {
		return s
	}
	return s[:n] + "..."
}