package handlers

import (
	"bytes"
	"html/template"
	"path/filepath"
	"strings"
	"testing"

	"task-dashboard/internal/models"
)

// renderShoppingTab renders the real shopping-tab template with the real func
// map, so these assertions cover what actually ships rather than a stand-in.
func renderShoppingTab(t *testing.T, data any) string {
	t.Helper()
	dir := filepath.Join("..", "..", "web", "templates")

	tmpl, err := template.New("").Funcs(templateFuncMap()).ParseGlob(filepath.Join(dir, "*.html"))
	if err != nil {
		t.Fatalf("parsing top-level templates: %v", err)
	}
	if _, err := tmpl.ParseGlob(filepath.Join(dir, "partials", "*.html")); err != nil {
		t.Fatalf("parsing partials: %v", err)
	}

	var buf bytes.Buffer
	if err := tmpl.ExecuteTemplate(&buf, "shopping-tab", data); err != nil {
		t.Fatalf("executing shopping-tab: %v", err)
	}
	return buf.String()
}

func twoStoreTabData() any {
	return struct {
		Stores  []models.ShoppingStore
		Grouped bool
	}{
		Stores: []models.ShoppingStore{
			{Name: "Costco", Categories: []models.ShoppingCategory{
				{Name: "", Items: []models.UnifiedShoppingItem{
					{ID: "user-1", Name: "Milk", Store: "Costco", Source: "user"},
				}},
			}},
			{Name: "Hardware Store", Categories: []models.ShoppingCategory{
				{Name: "", Items: []models.UnifiedShoppingItem{
					{ID: "user-2", Name: "Screws", Store: "Hardware Store", Source: "user"},
				}},
			}},
		},
		Grouped: true,
	}
}

// The inline per-store add form used to submit with a bare
// hx-swap="innerHTML". Because that form lives *inside* the swap target
// (#shopping-items-list), submitting it destroys the form mid-request and the
// page ends up scrolled to the bottom instead of staying where the user was.
// The quick-add form at the top already pinned this with an explicit
// scroll: modifier; the per-store forms did not.
func TestShoppingTab_InlineAddScrollsToItsOwnStore(t *testing.T) {
	html := renderShoppingTab(t, twoStoreTabData())

	for _, want := range []string{
		`id="store-costco"`,
		`id="store-hardware-store"`,
		`scroll:#store-costco:top`,
		`scroll:#store-hardware-store:top`,
	} {
		if !strings.Contains(html, want) {
			t.Errorf("rendered shopping tab is missing %q", want)
		}
	}
}

// Every inline add form must carry a scroll target. A form without one is the
// bug, and it is easy to reintroduce by adding a new store section by copy.
func TestShoppingTab_EveryInlineAddFormHasAScrollTarget(t *testing.T) {
	html := renderShoppingTab(t, twoStoreTabData())

	// Count the class attribute specifically — a bare "inline-add-form" also
	// matches the string literal in the page's own JS handler.
	forms := strings.Count(html, `class="inline-add-form`)
	scrolls := strings.Count(html, "scroll:#store-")
	if forms == 0 {
		t.Fatal("expected at least one inline add form in the grouped view")
	}
	if forms != scrolls {
		t.Errorf("found %d inline add forms but %d scroll targets; every form needs one",
			forms, scrolls)
	}
}

func TestSlug(t *testing.T) {
	slug, ok := templateFuncMap()["slug"].(func(string) string)
	if !ok {
		t.Fatal("templateFuncMap has no slug function of type func(string) string")
	}

	cases := []struct{ in, want string }{
		{"Costco", "costco"},
		{"Hardware Store", "hardware-store"},
		{"Trader Joe's", "trader-joe-s"},
		{"  Spaced  Out  ", "spaced-out"},
		{"Multiple---Dashes", "multiple-dashes"},
		// Non-ASCII is treated as a separator rather than transliterated. That
		// keeps the id valid without pulling in a transliteration table; the
		// result only has to be stable and unique, not pretty.
		{"Ünïcode Störe", "n-code-st-re"},
		{"", "unnamed"},
		{"!!!", "unnamed"},
	}
	for _, c := range cases {
		if got := slug(c.in); got != c.want {
			t.Errorf("slug(%q) = %q, want %q", c.in, got, c.want)
		}
	}
}

// Two stores whose names differ only by punctuation must not collide into the
// same element id, or the scroll target becomes ambiguous.
func TestSlug_DistinguishesSimilarNames(t *testing.T) {
	slug := templateFuncMap()["slug"].(func(string) string)
	if slug("Store A") == slug("Store B") {
		t.Error("distinct store names produced the same slug")
	}
}