commit c04544838dab848be1b1eca6c7527e4a3d6f4e9b
Author: Karchnu <karchnu@karchnu.fr>
Date:   Sun Nov 1 16:28:02 2020 +0100

    Initial commit for the generic mailer.

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..8f0270e
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+shard.lock
+bin
+drop
+lib
diff --git a/shard.yml b/shard.yml
new file mode 100644
index 0000000..69b7020
--- /dev/null
+++ b/shard.yml
@@ -0,0 +1,21 @@
+name: mailerd
+version: 0.1.0
+
+description: |
+  Simple email sending service.
+
+dependencies:
+  kemal:
+    github: kemalcr/kemal
+  crinja:
+    github: straight-shoota/crinja
+  email:
+    github: arcage/crystal-email
+  authd:
+    git: https://git.baguette.netlib.re/Baguette/authd.git
+
+targets:
+  mailerd:
+    main: src/mailer.cr
+
+license: ISC
diff --git a/src/mailer.cr b/src/mailer.cr
new file mode 100644
index 0000000..7407c8d
--- /dev/null
+++ b/src/mailer.cr
@@ -0,0 +1,227 @@
+require "email"
+require "option_parser"
+require "baguette-crystal-base"
+
+require "crinja"
+
+class Context
+	class_property simulation : Bool = false
+	class_property command    : String = "undefined"
+
+	class_property args       = [] of String
+end
+
+class Baguette::Configuration
+	class Mailer < Base
+		# Default mailer: 127.0.0.1, not "localhost" for glibc fuckery reasons.
+		# Without domain name resolution, one can statically compile the mailer
+		# for machines without glibc (such as on alpine linux).
+		property smtpd_host : String = "127.0.0.1"
+		property smtpd_port : UInt16 = 25
+
+		property verbosity  : Int32 = 3
+
+		# template => subject
+		property templates            : YAML::Any? = nil
+		property templates_directory  : String = "templates/"
+
+		def initialize
+		end
+	end
+end
+
+
+class OptionParser
+	def to_s(io : IO)
+		if banner = @banner
+			io << banner
+			io << "\n\n"
+		end
+		@flags.join io, "\n"
+	end
+end
+
+opt_simulation = -> (parser : OptionParser) {
+	parser.on "-s", "--simulation", "Simulation: do not do anything." do
+		Context.simulation = true
+		Baguette::Log.info "Simulation."
+	end
+}
+
+unrecognized_args_to_context_args = -> (parser : OptionParser,
+	nexact   : Int32?,
+	at_least : Int32?) {
+
+	# With the right args, these will be interpreted as serialized data.
+	parser.unknown_args do |args|
+
+		# either we test with the exact expected number of arguments or the least.
+		if exact = nexact
+			if args.size != exact
+				Baguette::Log.error "#{parser}"
+				exit 1
+			end
+		elsif least = at_least
+			if args.size < least
+				Baguette::Log.error "#{parser}"
+				exit 1
+			end
+		else
+			Baguette::Log.error "Number of parameters not even provided!"
+			Baguette::Log.error "#{parser}"
+			exit 1
+		end
+
+		args.each do |arg|
+			Baguette::Log.debug "Unrecognized argument: #{arg} (adding to Context.args)"
+			if Context.args.nil?
+				Context.args = Array(String).new
+			end
+			Context.args.not_nil! << arg
+		end
+	end
+}
+
+opt_help = -> (parser : OptionParser) {
+	parser.on "-h", "--help", "Prints command usage." do
+		puts "usage: #{PROGRAM_NAME} command -h"
+		puts
+		puts parser
+
+		case Context.command
+		when /send/
+			#ENUM.names.each do |n|
+			#	Baguette::Log.warning "- #{n}"
+			#end
+		end
+
+		exit 0
+	end
+}
+
+
+parser = OptionParser.new do |parser|
+	parser.banner = "Welcome on the Altideal CLI administration."
+	parser.on "-v verbosity", "--verbosity v", "Verbosity. From 0 to 4 (debug)." do |v|
+		Baguette::Context.verbosity = v.to_i
+		Baguette::Log.info "verbosity = #{v}"
+	end
+
+	opt_simulation.call parser
+
+	parser.on("send", "Send an email.") do
+		parser.banner = "usage: send <template> <email>"
+		Baguette::Log.info "sending an email"
+		Context.command = "send"
+		unrecognized_args_to_context_args.call parser, nil, 2
+	end
+
+	opt_help.call parser
+end
+
+parser.parse
+
+class Actions
+	property the_call             = {} of String => Proc(Nil)
+	property mailer_configuration : Baguette::Configuration::Mailer
+	property smtpd_client         : EMail::Client
+
+	def initialize(@mailer_configuration, @smtpd_client)
+		@the_call["send"] = ->send
+	end
+
+	def env_params
+		{
+			"from"    => ENV["FROM"],
+			"subject" => ENV["SUBJECT"],
+		}
+	rescue e
+		Baguette::Log.error "#{e}"
+		exit 1
+	end
+
+	# One-shot email transfer.
+	def send
+		template, to = Context.args.not_nil!
+		Baguette::Log.info "sending #{template} to #{to}"
+
+		template_parameters = if t = @mailer_configuration.templates
+			if t[template]?
+				{
+					"from"    => t[template]["from"].to_s,
+					"subject" => t[template]["subject"].to_s,
+				}
+			else
+				env_params
+			end
+		else
+			env_params
+		end
+
+		env = Crinja.new
+		env.loader = Crinja::Loader::FileSystemLoader.new @mailer_configuration.templates_directory
+
+		# Getting 'subject' and 'from' through an environment variable or configuration, else raise.
+		subject = template_parameters["subject"]
+		from    = template_parameters["from"]
+
+		# Allow to rewrite the destination.
+		to = ENV["TO"]? || to
+
+		template = env.get_template "#{template}.j2"
+
+		if Context.simulation
+			Baguette::Log.info "(simulation) email to send should be:"
+			Baguette::Log.info "subject: #{subject}"
+			Baguette::Log.info "from:    #{from}"
+			Baguette::Log.info "to:      #{to}"
+			Baguette::Log.info "content: #{template.render ENV}"
+		else
+			content = template.render ENV
+
+			email = EMail::Message.new
+			email.from    from
+			email.to      to
+			email.subject subject
+			email.message content
+
+			smtpd_client.start do
+				# In this block, default receiver is client
+				send(email)
+			end
+		end
+	rescue e
+		Baguette::Log.error "#{e}"
+		exit 1
+	end
+end
+
+def main
+
+	mail_conf = if c = Baguette::Configuration::Mailer.get
+		c
+	else
+		Baguette::Configuration::Mailer.new
+	end
+
+	if Context.simulation
+		pp! mail_conf
+	end
+
+	smtpd_config = EMail::Client::Config.new mail_conf.smtpd_host, mail_conf.smtpd_port.to_i
+	smtpd_client = EMail::Client.new smtpd_config
+
+	actions = Actions.new mail_conf, smtpd_client
+
+	# Now we did read the intent, we should proceed doing what was asked.
+	begin
+		actions.the_call[Context.command].call
+	rescue e
+		Baguette::Log.info "The command is not recognized (or implemented): #{e}."
+	end
+
+rescue e
+	Baguette::Log.error "Exception: #{e}"
+end
+
+main