go-nc-exapp/navigation.go

package gonexapp

import (
	"html/template"
	"net/http"
)

// shellCSP lets the ExApp iframe render this document. AppAPI blanks a frame
// whose response omits frame-ancestors.
const shellCSP = "default-src 'none'; base-uri 'none'; form-action 'none'; frame-ancestors 'self'; script-src 'self' 'unsafe-inline'; style-src 'self' 'unsafe-inline'; connect-src 'self'; img-src 'self' data:; font-src 'self' data:"

// Item is one App navigation entry. The ExApp chooses the ids and labels.
// Children may nest. The shell does not interpret the ids.
// Icon is an optional same-origin image URL. NextcloudIcons names the core SVGs.
type Item struct {
	ID       string
	Label    string
	Icon     string
	Children []Item
}

// AppNavigation is the Files-style shell an ExApp mounts.
// Items, Page, and DefaultID are required. Header and MissingMessage are
// optional. SelectKey defaults to "item". Every other query parameter,
// including the Visit folder, is copied onto the corrected address.
// An ExApp that never calls Handler keeps its own page.
type AppNavigation struct {
	Items          func(*http.Request) []Item
	Page           func(*http.Request, string) (string, bool)
	Header         func(*http.Request) string
	DefaultID      string
	MissingMessage string
	SelectKey      string
	// Title is the document title. Empty means "App navigation".
	Title string
	// DisableTheme skips the Nextcloud theme stylesheets. The zero value
	// loads the active theme.
	DisableTheme bool
}

// Handler serves the shell. The selected item is the SelectKey query parameter.
// A missing item renders DefaultID, includes MissingMessage, and publishes the
// corrected query on data-address so the page can replace the address.
// Every parent starts expanded. Folding is client state for this document only.
func (n AppNavigation) Handler() http.Handler {
	return http.HandlerFunc(n.serve)
}

func (n AppNavigation) selectKey() string {
	if n.SelectKey != "" {
		return n.SelectKey
	}
	return "item"
}

func (n AppNavigation) serve(w http.ResponseWriter, r *http.Request) {
	var items []Item
	if n.Items != nil {
		items = n.Items(r)
	}
	asked := r.URL.Query().Get(n.selectKey())
	selected := n.DefaultID
	missing := false
	if asked != "" {
		if _, ok := findItem(items, asked); ok {
			selected = asked
		} else {
			missing = true
		}
	}
	page := ""
	if n.Page != nil {
		body, ok := n.Page(r, selected)
		if !ok && selected != n.DefaultID {
			missing = true
			selected = n.DefaultID
			body, ok = n.Page(r, selected)
		}
		if ok {
			page = body
		}
	}
	header := ""
	if n.Header != nil {
		header = n.Header(r)
	}
	msg := ""
	if missing {
		msg = n.MissingMessage
	}
	title := n.Title
	if title == "" {
		title = "App navigation"
	}
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	w.Header().Set("Content-Security-Policy", shellCSP)
	w.WriteHeader(http.StatusOK)
	// Status is already committed; a template error cannot change the response.
	_ = shellTmpl.Execute(w, shellView{
		Selected: selected,
		Address:  n.address(r, selected),
		Header:   template.HTML(header),
		Items:    viewItems(r, items, selected, n.address),
		Page:     template.HTML(page),
		Missing:  msg,
		Title:    title,
		Theme:    !n.DisableTheme,
	})
}

func (n AppNavigation) address(r *http.Request, id string) string {
	q := r.URL.Query()
	q.Set(n.selectKey(), id)
	return "?" + q.Encode()
}

func findItem(items []Item, id string) (Item, bool) {
	for _, it := range items {
		if it.ID == id {
			return it, true
		}
		if child, ok := findItem(it.Children, id); ok {
			return child, true
		}
	}
	return Item{}, false
}

type shellView struct {
	Selected string
	Address  string
	Header   template.HTML
	Items    []itemView
	Page     template.HTML
	Missing  string
	Title    string
	Theme    bool
}

type itemView struct {
	ID          string
	Label       string
	Icon        string
	Href        string
	Current     bool
	HasChildren bool
	Children    []itemView
}

func viewItems(r *http.Request, items []Item, selected string, href func(*http.Request, string) string) []itemView {
	out := make([]itemView, 0, len(items))
	for _, it := range items {
		children := viewItems(r, it.Children, selected, href)
		out = append(out, itemView{
			ID:          it.ID,
			Label:       it.Label,
			Icon:        it.Icon,
			Href:        href(r, it.ID),
			Current:     it.ID == selected,
			HasChildren: len(children) > 0,
			Children:    children,
		})
	}
	return out
}

var shellTmpl = template.Must(template.New("shell").Parse(`<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>{{.Title}}</title>
{{if .Theme}}
<link rel="stylesheet" href="/apps/theming/css/default.css">
<link rel="stylesheet" href="/index.php/apps/theming/theme/default.css">
<link rel="stylesheet" href="/index.php/apps/theming/theme/dark.css">
<script>
(function () {
  var root = document.documentElement;
  try {
    var parent = window.parent && window.parent !== window ? window.parent.document.documentElement : null;
    if (parent) {
      for (var i = 0; i < parent.attributes.length; i++) {
        var attr = parent.attributes[i];
        if (attr.name.indexOf("data-theme") === 0) {
          root.setAttribute(attr.name, attr.value);
        }
      }
    }
  } catch (e) {}
  if (!root.hasAttribute("data-theme-default") && !root.hasAttribute("data-theme-dark") && !root.hasAttribute("data-theme-light")) {
    var dark = window.matchMedia("(prefers-color-scheme: dark)").matches;
    root.setAttribute(dark ? "data-theme-dark" : "data-theme-default", "");
  }
})();
</script>
{{end}}
<style>
  :root {
    --color-main-background: #ffffff;
    --color-main-text: #222222;
    --color-background-hover: #f5f5f5;
    --color-background-dark: #ededed;
    --color-primary-element: #00679e;
    --color-primary-element-light: #e5f0f8;
    --color-border: #ededed;
    --default-clickable-area: 34px;
    --border-radius-element: 8px;
  }
  html, body {
    min-height: 100%;
    color: var(--color-main-text);
    background-color: var(--color-background-plain, var(--color-main-background));
    background-image: var(--image-background);
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
  }
  body { margin: 0; font: 15px/1.4 var(--font-face, system-ui, sans-serif); }
  #app-nav { display: flex; flex-direction: column; min-height: 100vh; background: transparent; }
  #nav-header { padding: 8px 12px; border-bottom: 1px solid var(--color-border); }
  #app-nav-body { display: flex; flex: 1; min-height: 0; }
  nav.app-navigation {
    width: var(--navigation-width, 300px);
    flex: none;
    background-color: var(--color-main-background-translucent, var(--color-main-background));
    backdrop-filter: var(--filter-background-blur, none);
    -webkit-backdrop-filter: var(--filter-background-blur, none);
    border-inline-end: 1px solid var(--color-border);
    padding: 8px;
    overflow: auto;
  }
  main { flex: 1; padding: 16px; min-width: 0; background-color: var(--color-main-background); }
  .app-navigation-list, .app-navigation-entry__children { list-style: none; margin: 0; padding: 0; }
  .app-navigation-entry__children { padding-inline-start: 10px; }
  .app-navigation-entry-wrapper { display: flex; flex-wrap: wrap; width: 100%; }
  .app-navigation-entry {
    display: flex;
    align-items: stretch;
    width: 100%;
    min-height: var(--default-clickable-area);
    border-radius: var(--border-radius-element);
    position: relative;
  }
  .app-navigation-entry:hover { background: var(--color-background-hover); }
  .app-navigation-entry.active { background: var(--color-primary-element-light); }
  .app-navigation-entry.active::before {
    content: "";
    position: absolute;
    inset-block: 8px;
    inset-inline-start: 0;
    width: 3px;
    background: var(--color-primary-element);
    border-radius: 999px;
  }
  .app-navigation-entry-link {
    display: flex;
    flex: 1 1 auto;
    align-items: center;
    min-width: 0;
    min-height: var(--default-clickable-area);
    padding: 0 8px 0 12px;
    color: inherit;
    text-decoration: none;
    font-weight: 500;
  }
  .app-navigation-entry-icon {
    width: 16px;
    height: 16px;
    margin-inline-end: 8px;
    flex: none;
    filter: var(--background-invert-if-dark, none);
  }
  .app-navigation-entry__name { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
  .app-navigation-entry.active .app-navigation-entry__name { font-weight: 700; }
  .app-navigation-entry__utils { display: flex; align-items: center; }
  button.fold {
    width: var(--default-clickable-area);
    height: var(--default-clickable-area);
    margin: 0;
    padding: 0;
    border: 0;
    background: transparent;
    color: inherit;
    cursor: pointer;
    border-radius: var(--border-radius-element);
    display: flex;
    align-items: center;
    justify-content: center;
  }
  button.fold:hover { background: var(--color-background-dark); }
  button.fold svg { width: 16px; height: 16px; transition: transform .15s ease; }
  li[data-expanded="false"] > .app-navigation-entry__children { display: none; }
  li[data-expanded="false"] button.fold svg { transform: rotate(-90deg); }
  #nav-missing { margin: 0 0 1rem; }
</style>
</head>
<body data-selected="{{.Selected}}" data-address="{{.Address}}">
<div id="app-nav">
  <div id="nav-header">{{.Header}}</div>
  <div id="app-nav-body">
    <nav class="app-navigation" aria-label="App navigation">
      <ul class="app-navigation-list">{{template "items" .Items}}</ul>
    </nav>
    <main>
      {{if .Missing}}<p id="nav-missing">{{.Missing}}</p>{{end}}
      {{.Page}}
    </main>
  </div>
</div>
<script>
(function () {
  var addr = document.body.getAttribute("data-address");
  if (addr && addr !== location.search) {
    history.replaceState(null, "", addr);
  }
  document.querySelectorAll("button.fold").forEach(function (btn) {
    btn.addEventListener("click", function () {
      var li = btn.closest("li");
      var open = li.getAttribute("data-expanded") === "true";
      li.setAttribute("data-expanded", open ? "false" : "true");
      li.classList.toggle("app-navigation-entry--opened", !open);
      btn.setAttribute("aria-expanded", open ? "false" : "true");
    });
  });
})();
</script>
</body>
</html>

{{define "items"}}{{range .}}<li class="app-navigation-entry-wrapper{{if .HasChildren}} app-navigation-entry--collapsible app-navigation-entry--opened{{end}}" data-id="{{.ID}}"{{if .HasChildren}} data-expanded="true"{{end}}><div class="app-navigation-entry{{if .Current}} active{{end}}"><a class="app-navigation-entry-link" href="{{.Href}}"{{if .Current}} aria-current="page"{{end}}>{{if .Icon}}<img class="app-navigation-entry-icon" src="{{.Icon}}" alt="">{{end}}<span class="app-navigation-entry__name">{{.Label}}</span></a>{{if .HasChildren}}<div class="app-navigation-entry__utils"><button type="button" class="fold" aria-expanded="true" aria-label="Fold {{.Label}}"><svg viewBox="0 0 16 16" aria-hidden="true"><path d="M4.5 6.5 8 10l3.5-3.5" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round"/></svg></button></div>{{end}}</div>{{if .HasChildren}}<ul class="app-navigation-entry__children">{{template "items" .Children}}</ul>{{end}}</li>{{end}}{{end}}
`))