defmodule Temple do
  alias Temple.Parser

  @moduledoc """
  Temple syntax is available inside the `temple`, and is compiled into EEx at build time.

  ## Usage

  ```elixir
  temple do
    # You can define attributes by passing a keyword list to the element, the values can be literals or variables.
    class = "text-blue"
    id = "jumbotron"

    div class: class, id: id do
      # Text nodes can be emitted as string literals or variables.
      "Bob"

      id
    end

    # Attributes that result in boolean values will be emitted as a boolean attribute. Examples of boolean attributes are `disabled` and `checked`.

    input type: "text", disabled: true
    # <input type="text" disabled>

    input type: "text", disabled: false
    # <input type="text">

    # The class attribute also can take a keyword list of classes to conditionally render, based on the boolean result of the value.

    div class: ["text-red-500": false, "text-green-500": true ] do
      "Alert!"
    end

    # <div class="text-green-500">Alert!</div>

    # if and unless expressions can be used to conditionally render content
    if 5 > 0 do
      p do
        "Greater than 0!"
      end
    end

    unless 5 > 0 do
      p do
        "Less than 0!"
      end
    end

    # You can loop over items using for comprehensions
    for x <- 0..5 do
      div do
        x
      end
    end

    # You can use multiline anonymous functions, like if you're building a form in Phoenix
    form_for @changeset, Routes.user_path(@conn, :create), fn f ->
      "Name: "
      text_input f, :name
    end

    # You can explicitly emit a tag by prefixing with the Temple module
    Temple.div do
      "Foo"
    end

    # You can also pass children as a do key instead of a block
    div do: "Alice", class: "text-yellow"
  end
  ```

  ## Configuration

  ### Mode

  There are two "modes", `:normal` (the default) and `:live_view`.

  In `:live_view` mode, Temple emits markup that uses functions provided by Phoenix LiveView in order to be fully "diff trackable". These LiveView functions have not been released yet, so if you are going to combine Temple with LiveView, you need to use the latest unreleased default branch from GitHub.

  You should use `:live_view` mode even if you only have a single LiveView.

  ```elixir
  config :temple, :mode, :normal # default

  # or

  config :temple, :mode, :live_view
  ```

  ### Aliases

  You can add an alias for an element if there is a namespace collision with a function. If you are using `Phoenix.HTML`, there will be namespace collisions with the `<link>` and `<label>` elements.

  ```elixir
  config :temple, :aliases,
    label: :_label,
    link: :_link,
    select: :_select

  temple do
    _label do
      "Email"
    end

    _link href: "/css/site.css"
  end
  ```

  This will result in:

  ```html
  <label>
    Email
  </label>

  <link href="/css/site.css">
  ```
  """

  defmacro __using__(_) do
    quote location: :keep do
      import Temple
      require Temple.Component
    end
  end

  @doc """
  Context for temple markup.

  Returns an EEx string that can be passed into an EEx template engine.

  ## Usage

  ```elixir
  import Temple

  temple do
    div class: @class do
      "Hello, world!"
    end
  end

  # <div class="<%= @class %>">
  #   Hello, world!
  # </div>
  ```
  """
  defmacro temple([do: block] = _block) do
    markup =
      block
      |> Parser.parse()
      |> Enum.map(&Temple.Generator.to_eex/1)
      |> :erlang.iolist_to_binary()

    quote location: :keep do
      unquote(markup)
    end
  end

  defmacro temple(block) do
    quote location: :keep do
      unquote(block)
      |> Parser.parse()
      |> Enum.map(&Temple.Generator.to_eex/1)
      |> :erlang.iolist_to_binary()
    end
  end

  @doc """
  Compiles temple markup into a quoted expression using the given EEx Engine.

  Returns the same output that Phoenix templates output into the `render/1` function of their view modules.

  ## Usage

  ```elixir
  require Temple

  Temple.compile Phoenix.HTML.Engine do
    div class: @class do
      "Hello, world!"
    end
  end

  ```
  """
  defmacro compile(engine, [do: block] = _block) do
    markup =
      block
      |> Parser.parse()
      |> Enum.map(&Temple.Generator.to_eex/1)
      |> :erlang.iolist_to_binary()

    EEx.compile_string(markup, engine: engine, line: __CALLER__.line, file: __CALLER__.file)
  end
end