From f9c24c716653e81771c1f97e9c3a082a7863138d Mon Sep 17 00:00:00 2001
From: "Dirk-Jan C. Binnema" <djcb@djcbsoftware.nl>
Date: Sat, 31 May 2025 12:41:37 +0300
Subject: [PATCH] mu: add 'scm' command

Add the "scm" command, the way to get a Guile/Scheme shell.

This is experimental but will replace the current guile support in guile/ at
some point.
---
 meson.build       |  9 +++++++++
 meson_options.txt |  7 ++++++-
 mu/mu-cmd-info.cc | 16 ++++++++++++++--
 mu/mu-cmd.cc      | 19 ++++++++++++++++++-
 mu/mu-options.cc  | 14 +++++++++++++-
 mu/mu-options.hh  | 14 +++++++++++++-
 6 files changed, 73 insertions(+), 6 deletions(-)

diff --git a/meson.build b/meson.build
index c47663d7..0a5cd583 100644
--- a/meson.build
+++ b/meson.build
@@ -306,6 +306,15 @@ if not get_option('guile').disabled() and guile_dep.found()
   subdir('guile')
 endif
 
+# this must happen _after_ subdir('lib')
+if not get_option('scm').disabled() and guile_dep.found()
+  config_h_data.set('BUILD_SCM', 1)
+  subdir('scm')
+else
+  # dummy-dep.
+  mu_scm_dep = declare_dependency('', required:false)
+endif
+
 subdir('mu')
 
 # emacs -- needed for mu4e compilation
diff --git a/meson_options.txt b/meson_options.txt
index c0366bd8..35c74c96 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -35,7 +35,7 @@ option('lispdir',
 
 
 #
-# guile
+# guile & scm
 #
 
 option('guile',
@@ -48,6 +48,11 @@ option('guile-extension-dir',
        type: 'string',
        description: 'custom install path for the guile extension module')
 
+option('scm',
+       type : 'feature',
+       value: 'auto',
+       description: 'build the guile scripting support (requires guile-3.x)')
+
 #
 # misc
 #
diff --git a/mu/mu-cmd-info.cc b/mu/mu-cmd-info.cc
index 257c9093..b52fef90 100644
--- a/mu/mu-cmd-info.cc
+++ b/mu/mu-cmd-info.cc
@@ -288,8 +288,20 @@ topic_mu(const Options& opts)
 			"yes"
 #else
 			"no"
-#endif
-		, "GNU Guile 3.x scripting support?"});
+#endif /*BUILD_GUILE*/
+		, "GNU Guile 3.x support (old)?"});
+
+	info.add_row({"scm-support",
+#if BUILD_SCM
+			"yes"
+#else
+			"no"
+#endif /*BUILD_SCM*/
+		, "GNU Guile 3.x support (new)?"});
+
+
+
+
 	info.add_row({"readline-support",
 #if HAVE_LIBREADLINE
 			"yes"
diff --git a/mu/mu-cmd.cc b/mu/mu-cmd.cc
index bcdca985..d14c355f 100644
--- a/mu/mu-cmd.cc
+++ b/mu/mu-cmd.cc
@@ -35,6 +35,10 @@
 #include "message/mu-message.hh"
 #include "message/mu-mime-object.hh"
 
+#if BUILD_GUILE
+#include "scm/mu-scm.hh"
+#endif/*BUILD_GUILE*/
+
 #include "utils/mu-error.hh"
 #include "utils/mu-utils-file.hh"
 #include "utils/mu-utils.hh"
@@ -43,7 +47,6 @@
 
 using namespace Mu;
 
-
 static Result<void>
 cmd_fields(const Options& opts)
 {
@@ -63,6 +66,17 @@ cmd_find(const Options& opts)
 		return mu_cmd_find(*store, opts);
 }
 
+static Result<void>
+cmd_scm(const Store& store, const Options& opts)
+{
+#if !BUILD_SCM
+	return Err(Error::Code::InvalidArgument,
+		   "scm/guile is not available in this build");
+#else
+	return Mu::Scm::run(Mu::Scm::Config{store, opts});
+#endif /*BUILD_SCM*/
+}
+
 
 static void
 show_usage(void)
@@ -133,6 +147,9 @@ Mu::mu_cmd_execute(const Options& opts) try {
 		return cmd_find(opts);
 	case Options::SubCommand::Info:
 		return with_readonly_store(mu_cmd_info, opts);
+	case Options::SubCommand::Scm:
+		return with_readonly_store(cmd_scm, opts);
+
 
 	/* writable store */
 
diff --git a/mu/mu-options.cc b/mu/mu-options.cc
index 2b969321..41876504 100644
--- a/mu/mu-options.cc
+++ b/mu/mu-options.cc
@@ -545,7 +545,15 @@ sub_server(CLI::App& sub, Options& opts)
 	sub.add_flag("--allow-temp-file", opts.server.allow_temp_file,
 		     "Allow for the temp-file optimization")
 		->excludes("--commands");
+}
 
+static void
+sub_scm(CLI::App& sub, Options& opts)
+{
+	sub.add_option("script-path", opts.scm.script_path, "Path to script")
+		->type_name("<path>");
+	sub.add_option("script-args", opts.scm.params, "Parameters for script")
+		->type_name("<parameters>");
 }
 
 static void
@@ -665,9 +673,13 @@ AssocPairs<SubCommand, CommandInfo, Options::SubCommandNum> SubCommandInfos= {{
 		  {Category::NeedsWritableStore,
 		  "remove", "Remove message from file-system and database", sub_remove }
 		},
+		{ SubCommand::Scm,
+		  {Category::None,
+		   "scm", "Start Guile/Scheme shell",sub_scm}
+		},
 		{ SubCommand::Script,
 		  // Note: SubCommand::Script is special; there's no literal
-		// "script" subcommand, there subcommands for all the scripts.
+		// "script" subcommand, there are subcommands for all the scripts.
 		  {Category::None,
 		   "script", "Invoke a script", {}}
 		},
diff --git a/mu/mu-options.hh b/mu/mu-options.hh
index bd5799a6..0b110c8e 100644
--- a/mu/mu-options.hh
+++ b/mu/mu-options.hh
@@ -40,6 +40,7 @@ struct Options {
 	using	SizeVec	     = std::vector<std::size_t>;
 	using	OptTStamp    = Option<std::time_t>;
 	using	OptFieldId   = Option<Field::Id>;
+	using   OptString    = Option<std::string>;
 	using	StringVec    = std::vector<std::string>;
 
 	/*
@@ -62,7 +63,7 @@ struct Options {
 
 	enum struct SubCommand {
 		Add, Cfind, Extract, Fields, Find, Help, Index,Info, Init, Mkdir,
-		Move, Remove, Script, Server, Verify, View,
+		Move, Remove, Scm, Script, Server, Verify, View,
 		// <private>
 		__count__
 	};
@@ -80,6 +81,7 @@ struct Options {
 			SubCommand::Mkdir,
 			SubCommand::Move,
 			SubCommand::Remove,
+			SubCommand::Scm,
 			SubCommand::Script,
 			SubCommand::Server,
 			SubCommand::Verify,
@@ -226,6 +228,16 @@ struct Options {
 		StringVec	files;			/**< Files to remove */
 	} remove;
 
+
+	/*
+	 * Scm
+	 */
+	struct Scm {
+		OptString script_path; /**< Path to script (optional) */
+		StringVec params;      /**< Parameters for script (after "--") */
+	} scm;
+
+
 	/*
 	 * Scripts (i.e., finding scriot)
 	 */