mu-view: add --format=html

Support showing the HTML body (if any) instead of the default plain-text
body.

Update manpage.

NEWS.org

@@ -19,6 +19,10 @@
     - what used to be the ~mu fields~ command has been merged into ~mu info~; i.e.,
  ~mu fields~ is now ~mu info fields~.
 
+    - ~mu view~ gained ~--format=html~ for it to output the HTML body of the message
+      rather than the (default) plain-text body. See its updated manpage for
+      details.
+
     - experimental: if you build ~mu~ with [[https://github.com/CLD2Owners/cld2][CLD2]] support (available in many Linux
       distros), ~mu~ will try to detect the language of the body of e-mail
       messages; you can then search by their ISO-639-1 code, e.g. ~mu find

man/mu-view.1.org

@@ -15,13 +15,21 @@ mu [common options] view [options] [<file> ...]
 message files and does =not= require the message to be indexed in the database.
 
 The command shows some common headers (From:, To:, Cc:, Bcc:, Subject: and
-Date:), the list of attachments and the plain-text body of the message (if any).
+Date:), the list of attachments and either the plain-text or html body of the
+message (if any), or its s-expression representation.
 
-If no message file is provided, the command expects the message on
+If no message file is provided, the command reads the message from
 standard-input.
 
 * VIEW OPTIONS
 
+** --format,-o  = <format>
+use the given output format, one of:
+
+- ~plain~ - use the plain-text body; this is the default
+- ~html~ - use the HTML body
+- ~sexp~ - show the S-expression representation of the message
+
 ** --summary-len=<number>
 instead of displaying the full message, output a summary based upon the first
 =<number>= lines of the message.

mu/mu-cmd-view.cc

@@ -85,29 +85,42 @@ print_field(const std::string& field, const std::string& val, bool color)
 static void
 body_or_summary(const Message& message, const Options& opts)
 {
-	gboolean    color;
+	const auto color{!opts.nocolor};
+	using Format = Options::View::Format;
 
-	color = !opts.nocolor;
+	std::string body, btype;
+	switch (opts.view.format) {
+	case Format::Plain:
+		btype = "plain text";
+		body = message.body_text().value_or("");
+		break;
+	case Format::Html:
+		btype = "html";
+		body = message.body_html().value_or("");
+		break;
+	default:
+		throw std::range_error("unsupported format"); // bug
+	}
 
-	const auto body{message.body_text()};
-	if (!body || body->empty()) {
+	if (body.empty()) {
 		if (any_of(message.flags() & Flags::Encrypted)) {
 			color_maybe(MU_COLOR_CYAN);
-			mu_println("[No text body found; message has encrypted parts]");
+			mu_println("[No {} body found; message does have encrypted parts]",
+				   btype);
 		} else {
 			color_maybe(MU_COLOR_MAGENTA);
-			mu_println("[No text body found]");
+			mu_println("[No {} body found]", btype);
 		}
 		color_maybe(MU_COLOR_DEFAULT);
 		return;
 	}
 
 	if (opts.view.summary_len) {
-		const auto summ{summarize(body->c_str(), *opts.view.summary_len)};
+		const auto summ{summarize(body, *opts.view.summary_len)};
 		print_field("Summary", summ, color);
 	} else {
-		mu_print_encoded("{}", *body);
-		if (!g_str_has_suffix(body->c_str(), "\n"))
+		mu_print_encoded("{}", body);
+		if (!g_str_has_suffix(body.c_str(), "\n"))
 			mu_println("");
 	}
 }
@@ -131,6 +144,8 @@ view_msg_plain(const Message& message, const Options& opts)
 	print_field("Tags", join(message.tags(), ", "), color);
 
 	print_field("Attachments",get_attach_str(message, opts), color);
+
+	mu_println("");
 	body_or_summary(message, opts);
 
 	return Ok();
@@ -143,7 +158,9 @@ handle_msg(const Message& message, const Options& opts)
 
 	switch (opts.view.format) {
 	case Format::Plain:
+	case Format::Html:
 		return view_msg_plain(message, opts);
+
 	case Format::Sexp:
 		return view_msg_sexp(message, opts);
 	default:
@@ -173,7 +190,8 @@ Mu::mu_cmd_view(const Options& opts)
 		const auto msgtxt = read_from_stdin();
 		if (!msgtxt)
 			return Err(msgtxt.error());
-		auto message = Message::make_from_text(*msgtxt,{}, message_options(opts.view));
+		auto message = Message::make_from_text(*msgtxt,{},
+						       message_options(opts.view));
 		if (!message)
 			return Err(message.error());
 		else

mu/mu-options.cc

@@ -497,10 +497,13 @@ static void
 sub_view(CLI::App& sub, Options& opts)
 {
 	using Format = Options::View::Format;
-	static constexpr InfoEnum<Format, 2> FormatInfos = {{
+	static constexpr InfoEnum<Format, 3> FormatInfos = {{
 			{ Format::Plain,
 			  {"plain", "Plain output"}
 			},
+			{ Format::Html,
+			  {"html", "Plain output with HTML body"}
+			},
 			{ Format::Sexp,
 			  {"sexp", "S-expressions"}
 			},

mu/mu-options.hh

@@ -237,7 +237,7 @@ struct Options {
 		bool	terminate;			/**< add \f between msgs in view */
 		OptSize summary_len;			/**< max # of lines for summary */
 
-		enum struct Format { Plain,  Sexp };
+		enum struct Format { Plain,  Sexp, Html };
 		Format format;				/**< output format*/
 
 		StringVec files;			/**< Message file(s) */