// Copyright (c) 2019-2021 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
module log

import os
import time
import term

// Level defines possible log levels used by `Log`
pub enum Level {
	fatal = 1
	error
	warn
	info
	debug
}

// tag returns the tag for log level `l` as a string.
fn tag_to_cli(l Level) string {
	return match l {
		.fatal { term.red('FATAL') }
		.error { term.red('ERROR') }
		.warn { term.yellow('WARN ') }
		.info { term.white('INFO ') }
		.debug { term.blue('DEBUG') }
	}
}

// tag returns the tag for log level `l` as a string.
fn tag_to_file(l Level) string {
	return match l {
		.fatal { 'FATAL' }
		.error { 'ERROR' }
		.warn { 'WARN ' }
		.info { 'INFO ' }
		.debug { 'DEBUG' }
	}
}

interface Logger {
	fatal(s string)
	error(s string)
	warn(s string)
	info(s string)
	debug(s string)
}

// Log represents a logging object
pub struct Log {
mut:
	level            Level
	output_label     string
	ofile            os.File
	output_to_file   bool // if true output to file else use stdout/stderr.
pub mut:
	output_file_name string // log output to this file
}

// set_level sets the internal logging to `level`.
pub fn (mut l Log) set_level(level Level) {
	l.level = level
}

// set_output_level sets the internal logging output to `level`.
pub fn (mut l Log) set_output_level(level Level) {
	l.level = level
}

// set_full_logpath sets the output label and output path from `full_log_path`.
pub fn (mut l Log) set_full_logpath(full_log_path string) {
	rlog_file := os.real_path(full_log_path)
	l.set_output_label(os.file_name(rlog_file))
	l.set_output_path(os.dir(rlog_file))
}

// set_output_label sets the `label` for the output.
pub fn (mut l Log) set_output_label(label string) {
	l.output_label = label
}

// set_output_path sets the file to which output is logged to.
pub fn (mut l Log) set_output_path(output_file_path string) {
	if l.ofile.is_opened {
		l.ofile.close()
	}
	l.output_to_file = true
	l.output_file_name = os.join_path(os.real_path(output_file_path), l.output_label)
	ofile := os.open_append(l.output_file_name) or {
		panic('error while opening log file $l.output_file_name for appending')
	}
	l.ofile = ofile
}

// flush writes the log file content to disk.
pub fn (mut l Log) flush() {
	l.ofile.flush()
}

// close closes the log file.
pub fn (mut l Log) close() {
	l.ofile.close()
}

// log_file writes log line `s` with `level` to the log file.
fn (mut l Log) log_file(s string, level Level) {
	timestamp := time.now().format_ss()
	e := tag_to_file(level)
	l.ofile.writeln('$timestamp [$e] $s')
}

// log_cli writes log line `s` with `level` to stdout.
fn (l &Log) log_cli(s string, level Level) {
	f := tag_to_cli(level)
	t := time.now()
	println('[$f $t.format_ss()] $s')
}

// send_output writes log line `s` with `level` to either the log file or stdout
// according to the value of the `.output_to_file` field.
fn (mut l Log) send_output(s &string, level Level) {
	if l.output_to_file {
		l.log_file(s, level)
	} else {
		l.log_cli(s, level)
	}
}

// fatal logs line `s` via `send_output` if `Log.level` is greater than or equal to the `Level.fatal` category.
pub fn (mut l Log) fatal(s string) {
	if int(l.level) < int(Level.fatal) {
		return
	}
	l.send_output(s, .fatal)
	l.ofile.close()
	panic('$l.output_label: $s')
}

// error logs line `s` via `send_output` if `Log.level` is greater than or equal to the `Level.error` category.
pub fn (mut l Log) error(s string) {
	if int(l.level) < int(Level.error) {
		return
	}
	l.send_output(s, .error)
}

// warn logs line `s` via `send_output` if `Log.level` is greater than or equal to the `Level.warn` category.
pub fn (mut l Log) warn(s string) {
	if int(l.level) < int(Level.warn) {
		return
	}
	l.send_output(s, .warn)
}

// info logs line `s` via `send_output` if `Log.level` is greater than or equal to the `Level.info` category.
pub fn (mut l Log) info(s string) {
	if int(l.level) < int(Level.info) {
		return
	}
	l.send_output(s, .info)
}

// debug logs line `s` via `send_output` if `Log.level` is greater than or equal to the `Level.debug` category.
pub fn (mut l Log) debug(s string) {
	if int(l.level) < int(Level.debug) {
		return
	}
	l.send_output(s, .debug)
}