make options pattern more generic with dot imports a bit less boilerplate for the user

8 files changed, 240 insertions, 119 deletions

diff --git a/internal/resource/dir/dir.go b/internal/resource/dir/dir.go
index 9c34486..8be4395 100644
--- a/internal/resource/dir/dir.go
+++ b/internal/resource/dir/dir.go
@@ -8,6 +8,7 @@ import (
 	"strconv"
 
 	"codeberg.org/snonux/gonf/internal/resource"
+	"codeberg.org/snonux/gonf/internal/resource/opt"
 )
 
 type Dir struct {
@@ -21,51 +22,28 @@ type Dir struct {
 	absent   bool
 }
 
-type Option func(*Dir)
+// SetSource implements opt.Sourced.
+func (d *Dir) SetSource(source string) { d.source = source }
 
-func WithSource(source string) Option {
-	return func(d *Dir) {
-		d.source = source
-	}
-}
+// SetOwner implements opt.Owner.
+func (d *Dir) SetOwner(user string) { d.user = user }
 
-func WithUser(user string) Option {
-	return func(d *Dir) {
-		d.user = user
-	}
-}
+// SetGroup implements opt.Grouped.
+func (d *Dir) SetGroup(group string) { d.group = group }
 
-func WithGroup(group string) Option {
-	return func(d *Dir) {
-		d.group = group
-	}
-}
+// SetMode implements opt.Moded (the directory's own mode).
+func (d *Dir) SetMode(mode os.FileMode) { d.mode = mode }
 
-func WithMode(mode os.FileMode) Option {
-	return func(d *Dir) {
-		d.mode = mode
-	}
-}
+// SetFileMode implements opt.FileModed (mode for files copied from source).
+func (d *Dir) SetFileMode(mode os.FileMode) { d.fileMode = mode }
 
-func WithFileMode(mode os.FileMode) Option {
-	return func(d *Dir) {
-		d.fileMode = mode
-	}
-}
+// SetPrune implements opt.Prunable.
+func (d *Dir) SetPrune() { d.prune = true }
 
-func WithPrune() Option {
-	return func(d *Dir) {
-		d.prune = true
-	}
-}
-
-func IsAbsent() Option {
-	return func(d *Dir) {
-		d.absent = true
-	}
-}
+// SetAbsent implements opt.Absentable.
+func (d *Dir) SetAbsent() { d.absent = true }
 
-func build(path string, opts ...Option) (*Dir, error) {
+func build(path string, opts ...opt.Option) (*Dir, error) {
 	curr, err := user.Current()
 	if err != nil {
 		return nil, fmt.Errorf("failed to get current user for default: %w", err)
@@ -79,8 +57,8 @@ func build(path string, opts ...Option) (*Dir, error) {
 		group:    curr.Gid,
 	}
 
-	for _, opt := range opts {
-		opt(d)
+	for _, o := range opts {
+		o(d)
 	}
 
 	return d, nil
@@ -200,7 +178,7 @@ func applyAttributesTo(path string, mode os.FileMode, usr, group string) error {
 
 // Ensure builds and applies the directory resource described by opts,
 // without registering it.
-func Ensure(path string, opts ...Option) error {
+func Ensure(path string, opts ...opt.Option) error {
 	d, err := build(path, opts...)
 	if err != nil {
 		return err
@@ -208,7 +186,7 @@ func Ensure(path string, opts ...Option) error {
 	return d.apply()
 }
 
-func Have(path string, opts ...Option) resource.Resource {
+func Have(path string, opts ...opt.Option) resource.Resource {
 	d, err := build(path, opts...)
 	if err != nil {
 		log.Fatalf("failed to apply directory resource %s: %v", path, err)
@@ -223,7 +201,7 @@ func Have(path string, opts ...Option) resource.Resource {
 	return res
 }
 
-func Absent(path string, opts ...Option) resource.Resource {
-	opts = append(opts, IsAbsent())
+func Absent(path string, opts ...opt.Option) resource.Resource {
+	opts = append(opts, opt.IsAbsent())
 	return Have(path, opts...)
 }
diff --git a/internal/resource/dir/dir_test.go b/internal/resource/dir/dir_test.go
index ca01535..5ffb5cf 100644
--- a/internal/resource/dir/dir_test.go
+++ b/internal/resource/dir/dir_test.go
@@ -6,6 +6,7 @@ import (
 	"testing"
 
 	"codeberg.org/snonux/gonf/internal/resource/file"
+	. "codeberg.org/snonux/gonf/internal/resource/opt"
 )
 
 func TestHaveDirectoryCreate(t *testing.T) {
@@ -296,7 +297,7 @@ func TestSourceCopyParamMatchesSingleFilePath(t *testing.T) {
 	}
 
 	singleTarget := filepath.Join(tmp, "single.conf")
-	if err := file.Ensure(singleTarget, file.WithSource(sourcePath)); err != nil {
+	if err := file.Ensure(singleTarget, WithSource(sourcePath)); err != nil {
 		t.Fatal(err)
 	}
 	viaFile, err := os.ReadFile(singleTarget)
diff --git a/internal/resource/dir/source.go b/internal/resource/dir/source.go
index 8f9b73a..2e5ed98 100644
--- a/internal/resource/dir/source.go
+++ b/internal/resource/dir/source.go
@@ -9,6 +9,7 @@ import (
 
 	"codeberg.org/snonux/gonf/internal/resource/file"
 	"codeberg.org/snonux/gonf/internal/resource/link"
+	"codeberg.org/snonux/gonf/internal/resource/opt"
 )
 
 // copySourceTree mirrors d.source into d.path, dispatching each entry by
@@ -63,7 +64,7 @@ func copySourceSymlink(sourcePath, target string) error {
 	if err != nil {
 		return fmt.Errorf("failed to read symlink %s: %w", sourcePath, err)
 	}
-	return link.Ensure(target, link.IsSymlink(rawTarget))
+	return link.Ensure(target, opt.WithSymlink(rawTarget))
 }
 
 // copySourceFile delegates writing a single copied file to the file
@@ -73,10 +74,10 @@ func copySourceSymlink(sourcePath, target string) error {
 // dir needs no special-casing of its own.
 func copySourceFile(d *Dir, sourcePath, target string) error {
 	return file.Ensure(target,
-		file.WithSource(sourcePath),
-		file.WithMode(d.fileMode),
-		file.WithUser(d.user),
-		file.WithGroup(d.group),
+		opt.WithSource(sourcePath),
+		opt.WithMode(d.fileMode),
+		opt.WithOwner(d.user),
+		opt.WithGroup(d.group),
 	)
 }
 
diff --git a/internal/resource/file/file.go b/internal/resource/file/file.go
index 257c407..6395403 100644
--- a/internal/resource/file/file.go
+++ b/internal/resource/file/file.go
@@ -11,6 +11,7 @@ import (
 	"text/template"
 
 	"codeberg.org/snonux/gonf/internal/resource"
+	"codeberg.org/snonux/gonf/internal/resource/opt"
 )
 
 type File struct {
@@ -23,47 +24,33 @@ type File struct {
 	absent  bool
 }
 
-type Option func(*File)
-
-func WithContent(content string) Option {
-	return func(f *File) {
-		f.content = content
-		f.source = ""
-	}
+// SetContent implements opt.Contented. Setting literal content clears any
+// previously configured source, as the two are mutually exclusive.
+func (f *File) SetContent(content string) {
+	f.content = content
+	f.source = ""
 }
 
-func WithSource(source string) Option {
-	return func(f *File) {
-		f.source = source
-		f.content = ""
-	}
+// SetSource implements opt.Sourced. Setting a source clears any previously
+// configured literal content, as the two are mutually exclusive.
+func (f *File) SetSource(source string) {
+	f.source = source
+	f.content = ""
 }
 
-func WithUser(user string) Option {
-	return func(f *File) {
-		f.user = user
-	}
-}
+// SetOwner implements opt.Owner.
+func (f *File) SetOwner(user string) { f.user = user }
 
-func WithGroup(group string) Option {
-	return func(f *File) {
-		f.group = group
-	}
-}
+// SetGroup implements opt.Grouped.
+func (f *File) SetGroup(group string) { f.group = group }
 
-func WithMode(mode os.FileMode) Option {
-	return func(f *File) {
-		f.mode = mode
-	}
-}
+// SetMode implements opt.Moded.
+func (f *File) SetMode(mode os.FileMode) { f.mode = mode }
 
-func IsAbsent() Option {
-	return func(f *File) {
-		f.absent = true
-	}
-}
+// SetAbsent implements opt.Absentable.
+func (f *File) SetAbsent() { f.absent = true }
 
-func build(path string, opts ...Option) (*File, error) {
+func build(path string, opts ...opt.Option) (*File, error) {
 	curr, err := user.Current()
 	if err != nil {
 		return nil, fmt.Errorf("failed to get current user for default: %w", err)
@@ -76,8 +63,8 @@ func build(path string, opts ...Option) (*File, error) {
 		group: curr.Gid,
 	}
 
-	for _, opt := range opts {
-		opt(f)
+	for _, o := range opts {
+		o(f)
 	}
 
 	return f, nil
@@ -222,7 +209,7 @@ func ensureAbsent(path string) error {
 // Ensure builds and applies the file resource described by opts, without
 // registering it. Used by other resource packages (e.g. dir) to write an
 // individual file without it becoming its own top-level resource.
-func Ensure(path string, opts ...Option) error {
+func Ensure(path string, opts ...opt.Option) error {
 	f, err := build(path, opts...)
 	if err != nil {
 		return err
@@ -230,7 +217,7 @@ func Ensure(path string, opts ...Option) error {
 	return f.apply()
 }
 
-func Have(path string, opts ...Option) resource.Resource {
+func Have(path string, opts ...opt.Option) resource.Resource {
 	f, err := build(path, opts...)
 	if err != nil {
 		log.Fatalf("failed to apply file resource %s: %v", path, err)
@@ -245,7 +232,7 @@ func Have(path string, opts ...Option) resource.Resource {
 	return res
 }
 
-func Absent(path string, opts ...Option) resource.Resource {
-	opts = append(opts, IsAbsent())
+func Absent(path string, opts ...opt.Option) resource.Resource {
+	opts = append(opts, opt.IsAbsent())
 	return Have(path, opts...)
 }
diff --git a/internal/resource/file/file_test.go b/internal/resource/file/file_test.go
index b3b7711..49deb4c 100644
--- a/internal/resource/file/file_test.go
+++ b/internal/resource/file/file_test.go
@@ -5,6 +5,8 @@ import (
 	"path/filepath"
 	"strings"
 	"testing"
+
+	. "codeberg.org/snonux/gonf/internal/resource/opt"
 )
 
 func TestGetChecksum(t *testing.T) {
diff --git a/internal/resource/link/link.go b/internal/resource/link/link.go
index 3133514..f9c6c8d 100644
--- a/internal/resource/link/link.go
+++ b/internal/resource/link/link.go
@@ -6,6 +6,7 @@ import (
 	"os"
 
 	"codeberg.org/snonux/gonf/internal/resource"
+	"codeberg.org/snonux/gonf/internal/resource/opt"
 )
 
 type kind int
@@ -23,32 +24,25 @@ type Link struct {
 	absent bool
 }
 
-type Option func(*Link)
-
-func IsSymlink(target string) Option {
-	return func(l *Link) {
-		l.kind = symlinkKind
-		l.target = target
-	}
+// SetSymlink implements opt.Linkable.
+func (l *Link) SetSymlink(target string) {
+	l.kind = symlinkKind
+	l.target = target
 }
 
-func IsHardlink(target string) Option {
-	return func(l *Link) {
-		l.kind = hardlinkKind
-		l.target = target
-	}
+// SetHardlink implements opt.Linkable.
+func (l *Link) SetHardlink(target string) {
+	l.kind = hardlinkKind
+	l.target = target
 }
 
-func IsAbsent() Option {
-	return func(l *Link) {
-		l.absent = true
-	}
-}
+// SetAbsent implements opt.Absentable.
+func (l *Link) SetAbsent() { l.absent = true }
 
-func build(path string, opts ...Option) *Link {
+func build(path string, opts ...opt.Option) *Link {
 	l := &Link{path: path}
-	for _, opt := range opts {
-		opt(l)
+	for _, o := range opts {
+		o(l)
 	}
 	return l
 }
@@ -87,11 +81,11 @@ func (l *Link) resourceType() string {
 // Ensure builds and applies the link resource described by opts, without
 // registering it. Used by other resource packages (e.g. dir) to recreate an
 // individual symlink without it becoming its own top-level resource.
-func Ensure(path string, opts ...Option) error {
+func Ensure(path string, opts ...opt.Option) error {
 	return build(path, opts...).apply()
 }
 
-func Have(path string, opts ...Option) resource.Resource {
+func Have(path string, opts ...opt.Option) resource.Resource {
 	l := build(path, opts...)
 	res := resource.Register(l.resourceType(), l.path)
 
@@ -102,8 +96,8 @@ func Have(path string, opts ...Option) resource.Resource {
 	return res
 }
 
-func Absent(path string, opts ...Option) resource.Resource {
-	opts = append(opts, IsAbsent())
+func Absent(path string, opts ...opt.Option) resource.Resource {
+	opts = append(opts, opt.IsAbsent())
 	return Have(path, opts...)
 }
 
diff --git a/internal/resource/link/link_test.go b/internal/resource/link/link_test.go
index 6f1b1bc..a892527 100644
--- a/internal/resource/link/link_test.go
+++ b/internal/resource/link/link_test.go
@@ -4,6 +4,8 @@ import (
 	"os"
 	"path/filepath"
 	"testing"
+
+	. "codeberg.org/snonux/gonf/internal/resource/opt"
 )
 
 func TestHaveSymlinkCreateAndIdempotent(t *testing.T) {
@@ -14,7 +16,7 @@ func TestHaveSymlinkCreateAndIdempotent(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	Have(link, IsSymlink(target))
+	Have(link, WithSymlink(target))
 	got, err := os.Readlink(link)
 	if err != nil {
 		t.Fatalf("readlink: %v", err)
@@ -45,7 +47,7 @@ func TestHaveSymlinkRepoints(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	Have(link, IsSymlink(newT))
+	Have(link, WithSymlink(newT))
 	got, err := os.Readlink(link)
 	if err != nil {
 		t.Fatal(err)
@@ -66,7 +68,7 @@ func TestHaveSymlinkMovesRealFileAside(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	Have(link, IsSymlink(target))
+	Have(link, WithSymlink(target))
 
 	got, err := os.Readlink(link)
 	if err != nil {
@@ -88,7 +90,7 @@ func TestHaveHardlinkCreateAndIdempotent(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	Have(link, IsHardlink(target))
+	Have(link, WithHardlink(target))
 
 	ti, err := os.Stat(target)
 	if err != nil {
@@ -121,7 +123,7 @@ func TestHaveHardlinkMovesRealFileAside(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	Have(link, IsHardlink(target))
+	Have(link, WithHardlink(target))
 
 	ti, err := os.Stat(target)
 	if err != nil {
@@ -142,7 +144,7 @@ func TestHaveHardlinkMovesRealFileAside(t *testing.T) {
 func TestHaveHardlinkMissingTarget(t *testing.T) {
 	dir := t.TempDir()
 	link := filepath.Join(dir, "link")
-	if err := Ensure(link, IsHardlink(filepath.Join(dir, "nope"))); err == nil {
+	if err := Ensure(link, WithHardlink(filepath.Join(dir, "nope"))); err == nil {
 		t.Error("expected error when hardlink target does not exist")
 	}
 }
diff --git a/internal/resource/opt/opt.go b/internal/resource/opt/opt.go
new file mode 100644
index 0000000..23f076d
--- /dev/null
+++ b/internal/resource/opt/opt.go
@@ -0,0 +1,156 @@
+// Package opt provides interface-based, resource-agnostic configuration
+// options shared by the file, dir, and link resource packages.
+//
+// It is designed to be dot-imported at call sites so options read as bare
+// WithMode(...) / WithOwner(...) calls regardless of the resource type:
+//
+//	import (
+//		"codeberg.org/snonux/gonf/internal/resource/file"
+//		. "codeberg.org/snonux/gonf/internal/resource/opt"
+//	)
+//
+//	file.Have("file.txt", WithOwner("paul"), WithMode(0o755))
+//
+// Each option targets a small capability interface (Owner, Moded, ...). A
+// resource implements only the setters it supports. Applying an option to a
+// resource that lacks the matching interface (e.g. WithPrune on a file) is a
+// programming error in the resource declaration and aborts the program via
+// log.Fatalf.
+package opt
+
+import (
+	"log"
+	"os"
+)
+
+// Option configures a resource. It is applied to the concrete resource value
+// (e.g. *file.File) during construction.
+type Option func(any)
+
+// Capability interfaces. A resource implements only the setters it supports.
+type (
+	Owner      interface{ SetOwner(string) }
+	Grouped    interface{ SetGroup(string) }
+	Moded      interface{ SetMode(os.FileMode) }
+	Sourced    interface{ SetSource(string) }
+	Contented  interface{ SetContent(string) }
+	FileModed  interface{ SetFileMode(os.FileMode) }
+	Prunable   interface{ SetPrune() }
+	Absentable interface{ SetAbsent() }
+	Linkable   interface {
+		SetSymlink(target string)
+		SetHardlink(target string)
+	}
+)
+
+// WithOwner sets the owning user of the resource.
+func WithOwner(owner string) Option {
+	return func(t any) {
+		r, ok := t.(Owner)
+		if !ok {
+			log.Fatalf("%T does not support WithOwner", t)
+		}
+		r.SetOwner(owner)
+	}
+}
+
+// WithGroup sets the owning group of the resource.
+func WithGroup(group string) Option {
+	return func(t any) {
+		r, ok := t.(Grouped)
+		if !ok {
+			log.Fatalf("%T does not support WithGroup", t)
+		}
+		r.SetGroup(group)
+	}
+}
+
+// WithMode sets the resource's own file mode.
+func WithMode(mode os.FileMode) Option {
+	return func(t any) {
+		r, ok := t.(Moded)
+		if !ok {
+			log.Fatalf("%T does not support WithMode", t)
+		}
+		r.SetMode(mode)
+	}
+}
+
+// WithSource sets the source path the resource is populated from.
+func WithSource(source string) Option {
+	return func(t any) {
+		r, ok := t.(Sourced)
+		if !ok {
+			log.Fatalf("%T does not support WithSource", t)
+		}
+		r.SetSource(source)
+	}
+}
+
+// WithContent sets literal content for the resource.
+func WithContent(content string) Option {
+	return func(t any) {
+		r, ok := t.(Contented)
+		if !ok {
+			log.Fatalf("%T does not support WithContent", t)
+		}
+		r.SetContent(content)
+	}
+}
+
+// WithFileMode sets the mode applied to regular files copied from a source
+// tree (distinct from the resource's own mode).
+func WithFileMode(mode os.FileMode) Option {
+	return func(t any) {
+		r, ok := t.(FileModed)
+		if !ok {
+			log.Fatalf("%T does not support WithFileMode", t)
+		}
+		r.SetFileMode(mode)
+	}
+}
+
+// WithPrune enables reconciliation of extra destination entries during a
+// source copy, and recursive removal during IsAbsent().
+func WithPrune() Option {
+	return func(t any) {
+		r, ok := t.(Prunable)
+		if !ok {
+			log.Fatalf("%T does not support WithPrune", t)
+		}
+		r.SetPrune()
+	}
+}
+
+// IsAbsent marks the resource for removal.
+func IsAbsent() Option {
+	return func(t any) {
+		r, ok := t.(Absentable)
+		if !ok {
+			log.Fatalf("%T does not support IsAbsent", t)
+		}
+		r.SetAbsent()
+	}
+}
+
+// WithSymlink makes the resource a symbolic link pointing at target.
+func WithSymlink(target string) Option {
+	return func(t any) {
+		r, ok := t.(Linkable)
+		if !ok {
+			log.Fatalf("%T does not support WithSymlink", t)
+		}
+		r.SetSymlink(target)
+	}
+}
+
+// WithHardlink makes the resource a hard link pointing at target.
+func WithHardlink(target string) Option {
+	return func(t any) {
+		r, ok := t.(Linkable)
+		if !ok {
+			log.Fatalf("%T does not support WithHardlink", t)
+		}
+		r.SetHardlink(target)
+	}
+}