Refactor html templates

This commit entirely refactors the use of html templates. Instead of
inheriting from a shared template, we insert the results into a base
template.

internal/dis/component/server/templating/flags.go

@@ -0,0 +1,101 @@
+package templating
+
+import (
+	"html/template"
+	"net/http"
+	"time"
+
+	"github.com/FAU-CDI/wisski-distillery/internal/dis/component"
+	"github.com/FAU-CDI/wisski-distillery/internal/dis/component/server/assets"
+	"github.com/tkw1536/goprogram/lib/reflectx"
+	"golang.org/x/exp/slices"
+)
+
+// Flags represent handle-updatable options for the base template
+type Flags struct {
+	Title         string // Title of the menu
+	assets.Assets        // assets are the assets included in the template
+
+	Crumbs  []component.MenuItem // crumbs are the breadcrumbs leading to a specific action
+	Actions []component.MenuItem // actions are the actions available to a specific thingy
+}
+
+// Apply applies a set of functions to this flags
+func (flags Flags) Apply(r *http.Request, funcs ...FlagFunc) Flags {
+	for _, f := range funcs {
+		flags = f(flags, r)
+	}
+	return flags
+}
+
+// RuntimeFlags are passed to the template at runtime.
+// Any context may e
+type RuntimeFlags struct {
+	Flags
+
+	RequestURI  string               // request uri of the current page
+	Menu        []component.MenuItem // menu at the top of the page
+	GeneratedAt time.Time            // time the underlying data returned
+	CSRF        template.HTML        // csrf data (if any)
+}
+
+var runtimeFlagsName = reflectx.TypeOf[RuntimeFlags]().Name()
+
+// Clone clones this flags
+func (flags Flags) Clone() Flags {
+	flags.Crumbs = slices.Clone(flags.Crumbs)
+	flags.Actions = slices.Clone(flags.Actions)
+	return flags
+}
+
+// FlagFunc updates a flags based on a request.
+// FlagFunc may not be nil.
+type FlagFunc func(flags Flags, r *http.Request) Flags
+
+// Assets sets the given assets for the given flags
+func Assets(Assets assets.Assets) FlagFunc {
+	return func(flags Flags, r *http.Request) Flags {
+		flags.Assets = Assets
+		return flags
+	}
+}
+
+// Crumbs sets the crumbs
+func Crumbs(crumbs ...component.MenuItem) FlagFunc {
+	return func(flags Flags, r *http.Request) Flags {
+		flags.Crumbs = crumbs
+		return flags
+	}
+}
+
+// Actions sets the actions
+func Actions(actions ...component.MenuItem) FlagFunc {
+	return func(flags Flags, r *http.Request) Flags {
+		flags.Actions = actions
+		return flags
+	}
+}
+
+// ReplaceAction replaces a specific action
+func ReplaceAction(index int, action component.MenuItem) FlagFunc {
+	return func(flags Flags, r *http.Request) Flags {
+		flags.Actions[index] = action
+		return flags
+	}
+}
+
+// ReplaceCrumb replaces a specific crum
+func ReplaceCrumb(index int, action component.MenuItem) FlagFunc {
+	return func(flags Flags, r *http.Request) Flags {
+		flags.Crumbs[index] = action
+		return flags
+	}
+}
+
+// Title sets the title of this template
+func Title(title string) FlagFunc {
+	return func(flags Flags, r *http.Request) Flags {
+		flags.Title = title
+		return flags
+	}
+}