cli, docs: Add a docs command for doc generation

This took a lot longer than it looks to get right. It's not perfect, but
it now reliably generates documentation which we can put into gohugo.

docs/util/metadata.go

@@ -0,0 +1,103 @@
+// Mgmt
+// Copyright (C) 2013-2024+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+//
+// Additional permission under GNU GPL version 3 section 7
+//
+// If you modify this program, or any covered work, by linking or combining it
+// with embedded mcl code and modules (and that the embedded mcl code and
+// modules which link with this program, contain a copy of their source code in
+// the authoritative form) containing parts covered by the terms of any other
+// license, the licensors of this program grant you additional permission to
+// convey the resulting work. Furthermore, the licensors of this program grant
+// the original author, James Shubin, additional permission to update this
+// additional permission if he deems it necessary to achieve the goals of this
+// additional permission.
+
+// Package util handles metadata for documentation generation.
+package util
+
+import (
+	"fmt"
+)
+
+var (
+	registeredResourceMetadata = make(map[string]*Metadata) // must initialize
+	registeredFunctionMetadata = make(map[string]*Metadata) // must initialize
+)
+
+// RegisterResource records the metadata for a resource of this kind.
+func RegisterResource(kind string, metadata *Metadata) error {
+	if _, exists := registeredResourceMetadata[kind]; exists {
+		return fmt.Errorf("metadata kind %s is already registered", kind)
+	}
+
+	registeredResourceMetadata[kind] = metadata
+
+	return nil
+}
+
+// LookupResource looks up the metadata for a resource of this kind.
+func LookupResource(kind string) (*Metadata, error) {
+	metadata, exists := registeredResourceMetadata[kind]
+	if !exists {
+		return nil, fmt.Errorf("not found")
+	}
+	return metadata, nil
+}
+
+// RegisterFunction records the metadata for a function of this name.
+func RegisterFunction(name string, metadata *Metadata) error {
+	if _, exists := registeredFunctionMetadata[name]; exists {
+		return fmt.Errorf("metadata named %s is already registered", name)
+	}
+
+	registeredFunctionMetadata[name] = metadata
+
+	return nil
+}
+
+// LookupFunction looks up the metadata for a function of this name.
+func LookupFunction(name string) (*Metadata, error) {
+	metadata, exists := registeredFunctionMetadata[name]
+	if !exists {
+		return nil, fmt.Errorf("not found")
+	}
+	return metadata, nil
+}
+
+// Metadata stores some additional information about the function or resource.
+// This is used to automatically generate documentation.
+type Metadata struct {
+	// Filename is the filename (without any base dir path) that this is in.
+	Filename string
+
+	// Typename is the string name of the main resource struct or function.
+	Typename string
+}
+
+// GetMetadata returns some metadata about the func. It can be called at any
+// time. This must not be named the same as the struct it's on or using it as an
+// anonymous embedded struct will stop us from being able to call this method.
+func (obj *Metadata) GetMetadata() *Metadata {
+	//if obj == nil { // TODO: Do I need this?
+	//	return nil
+	//}
+	return &Metadata{
+		Filename: obj.Filename,
+		Typename: obj.Typename,
+	}
+}