# Flamel

[![Elixir CI](https://github.com/themusicman/flamel/actions/workflows/elixir.yml/badge.svg)](https://github.com/themusicman/flamel/actions/workflows/elixir.yml)

This package is a bag of helper functions. Some might be questionable but they are what they are so use them as you will.

## Installation

If [available in Hex](https://hex.pm/packages/flamel), the package can be installed
by adding `flamel` to your list of dependencies in `mix.exs`:

```elixir
def deps do
  [
    {:flamel, "~> 1.3.0"}
  ]
end
```
or mainline the latest:
```elixir
def deps do
  [
    {:flamel, github: "themusicman/flamel", branch: "main"}
  ]
end
```

## Examples

### Context

Ability to create a context that can be used to build function pipelines

```elixir
alias Flamel.Context

context =
  %Context{}
  |> assign_user(user)
  |> authorize()
  |> perform_action()

if context.assigns[:action_performed?] do
  # something you are allowed to do
end

def assign_user?(%Context{} = context, user) do
  Context.assign(context, :user, user)
end

def authorize(%Context{assigns: %{user: %{type: :admin}} = context) do
  context
end

def authorize(%Context{} = context) do
  Context.halt!(context, "Not permitted")
end

def perform_action(%Context{halt?: true}) do
  # do nothing
  context
end

def perform_action(%Context{assigns: %{user: user}} = context) do
  # Do something
  Context.assign(context, %{action_performed_by: user, action_performed?: true})
end

```

You don't have to use `%Flamel.Context{}` because `Flamel.Context` uses protocols. You can implement the `Flamel.Contextable` protocol for your own data type. Look at the interals of `Flamel.Retryable.Exponential` and `Flamel.Retryable.Linear` for an example. 

### Retryable (experimental)

Retryable functions that retry based on different strategies. Right now Linear and Exponential are the only 2 implemented but you can implement your own since the retry strategy uses two protocols (`Flamel.Contextable` and `Flamel.Retryable.Strategy`). 

```elixir
strategy = %Flamel.Retryable.Linear{} # or Flamel.Retryable.linear()
Flamel.Retryable.try(strategy, fn strategy -> {:ok, "success", strategy} end)
{:ok, "success", strategy}
```

You can also assign values to the strategy since it implements `Flamel.Contextable`.

```elixir
strategy = %Flamel.Retryable.Exponential{} # or Flamel.Retryable.exponential()
import Flamel.Context

Flamel.Retryable.try(strategy, fn strategy ->
  case make_http_request(url, payload) do
    {:ok, result} ->
      {:ok, result, strategy}

    {:error, status, reason} ->
      {:error, reason, assign(strategy, :http_status, status)}
  end
end)

{:ok, "success", strategy}
```

There is a `Flamel.Retryable.Http` strategy but it currently just implements the Exponential strategy. The intent is to 
change the retry interval based on the HTTP status but this is not implemented yet. PRs are welcome. ;)

### Delayed Task (experimental)

Executes an `Task.async` with a delay.

```elixir
task =
  Flamel.Task.delay(
    interval_in_milliseconds,
    fn ->
      do_something()
    end
  )

result = Task.await(task)
```


### Utility 

```elixir
Flamel.try_and_return(fn -> :ok end) == :ok

Flamel.try_and_return(fn -> raise "error" end, {:ok, :default_value}) == {:ok, :default_value}

Flamel.unwrap_ok!({:ok, []}) == []

Flamel.unwrap_ok_or_nil({:error, "boom!"}) == nil

```

### Predicates

```elixir
Flamel.blank?(%{}) == true

# present is the opposite of blank?
Flamel.present?(%{}) == false
```

### Conversions

```elixir
Flamel.to_boolean("Y") == true

Flamel.to_integer(nil) == ""

Flamel.to_integer(1) == 1

Flamel.to_float(nil) == 0.0

Flamel.to_float(1) == 1.0

Flamel.to_string(nil) == ""
```

### DateTime

```elixir
Flamel.Moment.to_datetime("2000-10-31T01:30:00.000-05:00") == ~U[2000-10-31 06:30:00.000Z]

Flamel.Moment.to_datetime(~N[2019-10-31 23:00:07]) == ~N[2019-10-31 23:00:07]

Flamel.Moment.to_date(~D[2000-10-31]) == ~D[2000-10-31]

Flamel.Moment.to_date("2000-10-31") == ~D[2000-10-31]

Flamel.Moment.to_iso8601(~U[2000-10-31 06:30:00.000Z]) == "2000-10-31T06:30:00.000Z"

Flamel.Moment.to_iso8601(~D[2019-10-31]) == "2019-10-31"
```

### Maps/Structs

```elixir
Flamel.Map.atomize_keys(%{"first_name" => "Thomas", "dob" => "07/01/1981"}) == %{first_name: "Thomas", dob: "07/01/1981"}

map =
  Flamel.Map.assign(
    %{assigns: %{hobbies: ["playing"]}},
    :assigns,
    set: [name: "Osa"],
    push: [hobbies: ["soccer", "coloring"]]
  )

get_in(map, [:assigns, :hobbies]) == ["soccer", "coloring", "playing"]
get_in(map, [:assigns, :name]) == "Osa"

Flamel.Map.Indifferent.get(%{test: "value"}, "test") == "value"

Flamel.Map.Indifferent.get(%{test: "value"}, :test) == "value"

Flamel.Map.Safely.get(%Person{name: "Todd"}, &String.upcase(&1.name)) == "TODD"

Flamel.Map.Safely.get(%{name: "Todd"}, &String.upcase(&1.bad_field), "N/A") == "N/A"
```

All of the to_* functions are implemented using [Protocols](https://hexdocs.pm/elixir/1.16/protocols.html). So you can implement you own behavior for types that do not already have implementations.


Documentation can be generated with [ExDoc](https://github.com/elixir-lang/ex_doc)
and published on [HexDocs](https://hexdocs.pm). Once published, the docs can
be found at <https://hexdocs.pm/flamel>.