#! /usr/bin/env false

use v6.d;

use Log;
use Log::Level;

#| A simple implementation of Log.
unit class Log::Simple is Log;

#| An array of hashes. Each has must have a handle key, with an IO::Handle to
#| print messages to. A level key with an integer to signify a Log::Level is
#| also required.
has @!outputs;

#| A supplier to emit messages to.
has Supplier $!messages;

#| When enabled, include hostname in the log message. This can be useful when
#| running the application redundantly in a cluster with centralized logging.
has Bool $.hostname = False;

#| Send an emergency message.
multi method emergency (
	#| The message to print.
	Str:D $message,
) {
	$!messages.emit({
		message => self!message('emergency', $message),
		level => 0,
	})
}

#| Send a formatted emergency message.
multi method emergency (
	#| A printf-style format string.
	Str:D $format,

	#| Arguments to substitute into the format string placeholders.
	*@args,
) {
	$!messages.emit({
		message => self!message('emergency', $format.sprintf(|@args)),
		level => 0,
	})
}

#| Send an alert message.
multi method alert (
	#| The message to print.
	Str:D $message,
) {
	$!messages.emit({
		message => self!message('alert', $message),
		level => 1,
	})
}

#| Send a formatted alert message.
multi method alert (
	#| A printf-style format string.
	Str:D $format,

	#| Arguments to substitute into the format string placeholders.
	*@args,
) {
	$!messages.emit({
		message => self!message('alert', $format.sprintf(|@args)),
		level => 1,
	})
}

#| Send a critical message.
multi method critical (
	#| The message to print.
	Str:D $message,
) {
	$!messages.emit({
		message => self!message('critical', $message),
		level => 2,
	})
}

#| Send a formatted critical message.
multi method critical (
	#| A printf-style format string.
	Str:D $format,

	#| Arguments to substitute into the format string placeholders.
	*@args,
) {
	$!messages.emit({
		message => self!message('critical', $format.sprintf(|@args)),
		level => 2,
	})
}

#| Send an error message.
multi method error (
	#| The message to print.
	Str:D $message,
) {
	$!messages.emit({
		message => self!message('error', $message),
		level => 3,
	})
}

#| Send a formatted error message.
multi method error (
	#| A printf-style format string.
	Str:D $format,

	#| Arguments to substitute into the format string placeholders.
	*@args,
) {
	$!messages.emit({
		message => self!message('error', $format.sprintf(|@args)),
		level => 3,
	})
}

#| Send a warning message.
multi method warning (
	#| The message to print.
	Str:D $message,
) {
	$!messages.emit({
		message => self!message('warning', $message),
		level => 4,
	})
}

#| Send a formatted warning message.
multi method warning (
	#| A printf-style format string.
	Str:D $format,

	#| Arguments to substitute into the format string placeholders.
	*@args,
) {
	$!messages.emit({
		message => self!message('warning', $format.sprintf(|@args)),
		level => 4,
	})
}

#| Send a notice message. This is the "normal" level to publish log entries on.
multi method notice (
	#| The message to print.
	Str:D $message
) {
	$!messages.emit({
		message => self!message('notice', $message),
		level => 5,
	})
}

#| Send a formatted notice message. This is the "normal" level to publish log
#| entries on.
multi method notice (
	#| A printf-style format string.
	Str:D $format,

	#| Arguments to substitute into the format string placeholders.
	*@args,
) {
	$!messages.emit({
		message => self!message('notice', $format.sprintf(|@args)),
		level => 5,
	})
}

#| Send an informational message.
multi method info (
	#| The message to print.
	Str:D $message
) {
	$!messages.emit({
		message => self!message('info', $message),
		level => 6,
	})
}

#| Send a formatted informational message.
multi method info (
	#| The printf-style format string.
	Str:D $format,

	#| Arguments to substitute into the format string placeholders.
	*@args,
) {
	$!messages.emit({
		message => self!message('info', $format.sprintf(|@args)),
		level => 6,
	})
}

#| Send a debug message.
multi method debug (
	#| The message to print.
	Str:D $message,
) {
	$!messages.emit({
		message => self!message('debug', $message),
		level => 7,
	})
}

#| Send a formatted debug message.
multi method debug (
	#| A printf-style format string.
	Str:D $format,

	#| Arguments to substitute into the format string placeholders.
	*@args,
) {
	$!messages.emit({
		message => self!message('debug', $format.sprintf(|@args)),
		level => 7,
	})
}

#| Add an output to the logger.
multi method add-output (
	#| The IO::Handle to write log messages to.
	IO::Handle:D $handle,

	#| The log level for this particular stream.
	Int() $level where Log::Level::Emergency ≤ * ≤ Log::Level::Debug,

	#| A filter function to apply to any messages sent to the output.
	Callable :$filter?,
) {
	@!outputs.push({
		:$handle,
		:$level,
		:$filter,
	});
}

#| Convenience method to get the callee name. This is the package name if one
#| exists, or the source file name.
method !callee (
	#| The depth of which to get the callframe.
	Int:D $depth = 3,

	--> Str
) {
	my $file = callframe($depth).annotations<file>;

	return $file unless $file.ends-with(')');

	$file.words.tail.substr(1, *-1);
}

#| Convenience method for formatting the message as desired.
method !message (
	#| A human readable identifier for the level.
	Str:D $level,

	#| The original message to be logged.
	Str:D $message,

	--> Str
) {
	(
		DateTime.now.utc,
		($*KERNEL.hostname if $!hostname),
		self!callee,
		"<$level>",
	)».Str.join(' ') ~ ": $message"
}

submethod TWEAK
{
	# Set up the Supply for messages.
	$!messages .= new;
	$!messages.Supply.tap(sub (%payload) {
		@!outputs
			.race
			.grep(%payload<level> ≤ *<level>)
			.grep({ $_<filter> ?? $_<filter>(%payload).so !! True })
			.map(*<handle>.say(%payload<message>))
			;
	});
}

=begin pod

=NAME    Log::Simple
=VERSION 0.1.0
=AUTHOR  Patrick Spek <p.spek@tyil.nl>

=begin LICENSE
Copyright © 2020

This program is free software: you can redistribute it and/or modify it under
the terms of the GNU Affero 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 Affero General Public License for more
details.

You should have received a copy of the GNU Affero General Public License along
with this program.  If not, see http://www.gnu.org/licenses/.
=end LICENSE

=end pod

# vim: ft=raku noet sw=8 ts=8