defmodule File.Only.Logger.Proxy do
@moduledoc """
Implements logging messages to files only (not to the console).
"""
use PersistConfig
require Logger
alias __MODULE__.Try
@after_compile get_env(:after_compile)
@levels get_env(:levels)
@lib Mix.Project.config()[:app]
@line_length get_env(:line_length, 80)
@typedoc "Message to be logged"
@type message :: String.t() | iodata | fun | keyword | map
@doc """
Returns `true` if `value` is a positive integer, otherwise `false`.
"""
defguard is_pos_integer(value) when is_integer(value) and value > 0
@doc """
Writes `message` to the configured log file of logging level `level`.
## Examples
iex> alias File.Only.Logger.Proxy
iex> Proxy.log(:debug, "*** String message ***")
:ok
iex> alias File.Only.Logger.Proxy
iex> Proxy.log(:debug, ['*** Improper', 'List' | 'Message ***'])
:ok
iex> alias File.Only.Logger.Proxy
iex> Proxy.log(:debug, fn -> "*** Function message ***" end)
:ok
iex> alias File.Only.Logger.Proxy
iex> Proxy.log(:debug, %{'first' => 'Map', 'last' => 'Message'})
:ok
iex> alias File.Only.Logger.Proxy
iex> Proxy.log(:debug, first: 'Keyword', last: 'Message')
:ok
"""
@spec log(Logger.level(), message) :: :ok
def log(level, message) when level in @levels do
# `Logger.compare_levels/2` works when comparing an actual level to
# `:all` or `:none`. It also considers `:warn` and `:warning` equal.
#
# Logger.compare_levels(:emergency, :none) # => :lt
# Logger.compare_levels(:debug, :all) # => :gt
# Logger.compare_levels(:warn, :warning) # => :eq
# Logger.compare_levels(:warning, :warn) # => :eq
# Logger.compare_levels(:error, :warn) # => :gt
# Logger.compare_levels(:error, :warning) # => :gt
# Logger.compare_levels(:notice, :warning) # => :lt
# Logger.compare_levels(:notice, :warn) # => :lt
compare = Logger.compare_levels(level, level())
log(level, message, compare)
end
@doc """
Returns string "<module>.<function>/<arity>" e.g. "My.Math.sqrt/1" from the
given `env` (`Macro.Env`).
## Examples
iex> defmodule My.Math do
iex> alias File.Only.Logger.Proxy
iex> def sqrt(_number) do
iex> Proxy.fun(__ENV__)
iex> end
iex> end
iex> My.Math.sqrt(9)
"File.Only.Logger.ProxyTest.My.Math.sqrt/1"
"""
@spec fun(Macro.Env.t()) :: String.t()
def fun(%Macro.Env{function: {name, arity}, module: module} = _env) do
if to_string(name) |> String.contains?(" "),
do: "#{inspect(module)}.'#{name}'/#{arity}",
else: "#{inspect(module)}.#{name}/#{arity}"
end
def fun(%Macro.Env{function: nil}), do: "'not inside a function'"
@doc ~S'''
Will prefix `string` with "\n\s\s" if longer than `line_length` - `offset`.
You may use file `config/config.exs` or friends to configure `line_length`:
```elixir
import Config
config :file_only_logger, line_length: 80
```
```elixir
import Config
line_length =
try do
{keyword, _binding} = Code.eval_file(".formatter.exs")
keyword[:line_length] || 98
rescue
_error -> 80
end
config :file_only_logger, line_length: line_length
```
## Examples
iex> alias File.Only.Logger.Proxy
iex> supercal = "supercalifragilisticexpialidocious"
iex> heredoc = """
...> Feeling: #{supercal}
...> """
iex> Proxy.maybe_break(heredoc, 9)
"Feeling: supercalifragilisticexpialidocious\n"
iex> alias File.Only.Logger.Proxy
iex> supercal = "supercalifragilisticexpialidocious"
iex> heredoc = """
...> Feeling: #{supercal}ly #{supercal}
...> """
iex> Proxy.maybe_break(heredoc, 9) |> String.slice(0..57)
"\n\s\sFeeling: supercalifragilisticexpialidociously supercali"
'''
@spec maybe_break(String.t(), pos_integer, pos_integer) :: String.t()
def maybe_break(string, offset, line_length \\ @line_length)
when is_binary(string) and is_pos_integer(offset) and
is_pos_integer(line_length) do
if String.length(string) > line_length - offset,
do: "\n #{string}",
else: string
end
@doc """
Returns the application for the current process or module.
Returns `:undefined` if the current process does not belong to any
application or the current module is not listed in any application spec.
## Examples
iex> alias File.Only.Logger.Proxy
iex> Proxy.app
:file_only_logger
"""
@spec app :: atom
def app do
case :application.get_application() do
{:ok, app} -> app
:undefined -> Application.get_application(__MODULE__) || :undefined
end
end
@doc """
Returns the current library name.
## Examples
iex> alias File.Only.Logger.Proxy
iex> Proxy.lib
:file_only_logger
"""
@spec lib :: atom
def lib, do: @lib
@doc """
Returns the given `module` as a string.
## Examples
iex> alias File.Only.Logger.Proxy
iex> Proxy.mod(__MODULE__)
"File.Only.Logger.ProxyTest"
iex> alias File.Only.Logger.Proxy
iex> Proxy.mod(Elixir.Date.Range)
"Date.Range"
"""
@spec mod(module) :: String.t()
def mod(module), do: inspect(module)
@doc ~S'''
Returns a formatted heredoc to trace a message from the given `env`
(`Macro.Env`).
## Examples
iex> alias File.Only.Logger.Proxy
iex> heredoc = """
...> • App: file_only_logger
...> • Library: file_only_logger
...> • Function:\s
...> File.Only.Logger.ProxyTest.
...> """
...> |> String.trim_trailing()
iex> Proxy.from(__ENV__) =~ heredoc
true
'''
@spec from(Macro.Env.t()) :: String.t()
def from(env) do
"""
• App: #{app()}
• Library: #{lib()}
• Function: #{fun(env) |> maybe_break(12)}
"""
|> String.trim_trailing()
end
@doc ~S'''
Returns a formatted heredoc to trace a message from the given `env`
(`Macro.Env`) and `module`.
## Examples
iex> alias File.Only.Logger.Proxy
iex> heredoc = """
...> • App: file_only_logger
...> • Library: file_only_logger
...> • Module: File.Only.Logger.ProxyTest
...> • Function:\s
...> File.Only.Logger.ProxyTest.
...> """
...> |> String.trim_trailing()
iex> Proxy.from(__ENV__, __MODULE__) =~ heredoc
true
'''
@spec from(Macro.Env.t(), module) :: String.t()
def from(env, module) do
"""
• App: #{app()}
• Library: #{lib()}
• Module: #{mod(module)}
• Function: #{fun(env) |> maybe_break(12)}
"""
|> String.trim_trailing()
end
## Private functions
@spec level :: Logger.level() | :all | :none
defp level, do: get_env(:level, :all)
@dialyzer :no_match
@spec log(Logger.level(), message, :lt | :eq | :gt) :: :ok
defp log(level, message, compare) when compare in [:gt, :eq] do
removed = Try.remove_console_backend()
:ok = Logger.log(level, message)
if removed == :ok, do: Try.add_console_backend()
:ok
end
defp log(_level, _message, _compare), do: :ok
end
