defmodule Mix.Tasks.Devcon4.Install do
  @shortdoc "Set up devcontainer in your project"

  @moduledoc """
  Sets up devcontainer files in your project.

      mix devcon4.install

  ## What it does

    * Creates `.devcontainer/devcontainer.json` with container settings,
      volumes, and firewall initialization
    * Creates `.devcontainer/Dockerfile` with Elixir, Node.js, Claude Code,
      and development tools
    * Creates `.devcontainer/init-firewall.sh` with a restrictive outbound
      firewall (GitHub, Hex.pm, Anthropic API only)

  ## Options

    * `--elixir-version` - Elixir version for the base image (default: `1.18.3`)
    * `--erlang-version` - Erlang/OTP version for the base image (default: `27.3.3`)
    * `--ubuntu-version` - Ubuntu release codename (default: `noble`)
    * `--ubuntu-date-tag` - Ubuntu image date tag (default: `20260217`)
    * `--timezone` - Default timezone fallback (default: `America/Sao_Paulo`)
    * `--force` - Overwrite existing files without prompting
  """

  use Mix.Task

  @switches [
    elixir_version: :string,
    erlang_version: :string,
    ubuntu_version: :string,
    ubuntu_date_tag: :string,
    timezone: :string,
    force: :boolean
  ]

  @defaults [
    elixir_version: "1.18.3",
    erlang_version: "27.3.3",
    ubuntu_version: "noble",
    ubuntu_date_tag: "20260217",
    timezone: "America/Sao_Paulo",
    force: false
  ]

  @impl Mix.Task
  def run(argv) do
    {opts, _args} = OptionParser.parse!(argv, strict: @switches)
    opts = Keyword.merge(@defaults, opts)

    app_name = detect_app_name()
    project_name = humanize(app_name)
    volume_prefix = String.replace(app_name, "_", "-")

    File.mkdir_p!(".devcontainer")

    create_from_template(
      "devcontainer.json.eex",
      ".devcontainer/devcontainer.json",
      [
        project_name: project_name,
        volume_prefix: volume_prefix,
        timezone: opts[:timezone]
      ],
      opts[:force]
    )

    create_from_template(
      "Dockerfile.eex",
      ".devcontainer/Dockerfile",
      [
        elixir_version: opts[:elixir_version],
        erlang_version: opts[:erlang_version],
        ubuntu_version: opts[:ubuntu_version],
        ubuntu_date_tag: opts[:ubuntu_date_tag]
      ],
      opts[:force]
    )

    create_file(
      "init-firewall.sh",
      ".devcontainer/init-firewall.sh",
      opts[:force]
    )

    # Make firewall script executable
    File.chmod!(".devcontainer/init-firewall.sh", 0o755)

    Mix.shell().info("""

    Devcontainer files installed in .devcontainer/

    To start the container:

        # Via CLI
        devcontainer up --workspace-folder .
        devcontainer exec --workspace-folder . bash

        # Via VS Code
        Ctrl+Shift+P -> "Dev Containers: Reopen in Container"

    To customize, edit the generated files directly:
      - Add firewall domains in .devcontainer/init-firewall.sh
      - Add system packages in .devcontainer/Dockerfile
      - Change container settings in .devcontainer/devcontainer.json
    """)
  end

  defp create_from_template(template_name, target, assigns, force) do
    template = Devcon4.template_path(template_name)
    content = EEx.eval_file(template, assigns: assigns)
    write_file(target, content, force)
  end

  defp create_file(source_name, target, force) do
    source = Devcon4.template_path(source_name)
    content = File.read!(source)
    write_file(target, content, force)
  end

  defp write_file(target, content, force) do
    if File.exists?(target) and not force do
      Mix.shell().info("* skipping #{target} (already exists, use --force to overwrite)")
    else
      action = if File.exists?(target), do: "overwriting", else: "creating"
      Mix.shell().info("* #{action} #{target}")
      File.write!(target, content)
    end
  end

  defp detect_app_name do
    config = Mix.Project.config()
    config[:app] |> to_string()
  end

  defp humanize(name) do
    name
    |> String.replace("_", " ")
    |> String.split()
    |> Enum.map_join(" ", &String.capitalize/1)
  end
end