defmodule Mix.Tasks.Version do
  @shortdoc "Bump version and guide through release process"

  @moduledoc """
  Interactive Mix task for versioning and releasing Elixir packages.

  ## Usage

      mix version patch
      mix version minor
      mix version major

  This task will guide you through:
  1. Bumping the version number
  2. Updating mix.exs
  3. Collecting changelog entries
  4. Running tests (optional)
  5. Creating git commit and tag (optional)
  6. Pushing to remote (optional)

  ## Configuration

  You can customize the test command in your `config/config.exs`:

      config :versionise,
        test_command: "mix precommit"

  The default test command is `mix test`.
  """

  use Mix.Task

  alias Versionise.{Changelog, FileUpdater, Git, Prompter, Version}

  @impl Mix.Task
  def run(args) do
    args
    |> parse_args()
    |> execute_release()
  end

  @spec parse_args([String.t()]) :: :major | :minor | :patch | :help
  defp parse_args([bump_type]) when bump_type in ["major", "minor", "patch"] do
    String.to_existing_atom(bump_type)
  end

  defp parse_args(_args), do: :help

  @spec execute_release(:major | :minor | :patch | :help) :: :ok
  defp execute_release(:help) do
    show_help()
  end

  defp execute_release(bump_type) do
    perform_release(bump_type)
  end

  @spec perform_release(:major | :minor | :patch) :: :ok
  defp perform_release(bump_type) do
    with {:ok, current_version} <- get_current_version(),
         new_version <- Version.bump(current_version, bump_type),
         true <- confirm_version(current_version, new_version),
         :ok <- update_files(new_version),
         changelog_entries <- collect_changelog(),
         :ok <- Changelog.update_file(new_version, changelog_entries),
         :ok <- maybe_run_tests(),
         :ok <- maybe_git_operations(new_version) do
      show_completion_message()
    else
      {:error, reason} -> handle_error(reason)
      false -> handle_abort()
    end
  end

  @spec get_current_version() :: {:ok, Version.t()} | {:error, String.t()}
  defp get_current_version do
    FileUpdater.read_current_version()
  end

  @spec confirm_version(Version.t(), Version.t()) :: boolean()
  defp confirm_version(current_version, new_version) do
    current = Version.to_string(current_version)
    new = Version.to_string(new_version)

    Prompter.info("Current version: #{current}")
    Prompter.info("New version: #{new}")

    Prompter.confirm("Continue with version #{new}?")
  end

  @spec update_files(Version.t()) :: :ok | {:error, String.t()}
  defp update_files(new_version) do
    Prompter.section("Updating Files")

    new_version
    |> FileUpdater.update_mix_file()
    |> handle_file_update()
  end

  @spec handle_file_update(:ok | {:error, String.t()}) :: :ok | {:error, String.t()}
  defp handle_file_update(:ok) do
    Prompter.success("Updated mix.exs")
    :ok
  end

  defp handle_file_update({:error, _reason} = error), do: error

  @spec collect_changelog() :: Changelog.changelog_entries()
  defp collect_changelog do
    Changelog.collect_entries()
  end

  @spec maybe_run_tests() :: :ok | {:error, String.t()}
  defp maybe_run_tests do
    Prompter.section("Running Tests")
    test_command = get_test_command()

    if Prompter.confirm("Run test suite (#{test_command})?") do
      run_tests(test_command)
    else
      skip_tests()
    end
  end

  @spec get_test_command() :: String.t()
  defp get_test_command do
    Application.get_env(:versionise, :test_command, "mix test")
  end

  @spec skip_tests() :: :ok
  defp skip_tests do
    Prompter.info("Skipping tests")
    :ok
  end

  @spec run_tests(String.t()) :: :ok | {:error, String.t()}
  defp run_tests(test_command) do
    Prompter.info("Running #{test_command}...")

    test_command
    |> parse_command()
    |> execute_command()
    |> handle_test_result()
  end

  @spec parse_command(String.t()) :: {String.t(), [String.t()]}
  defp parse_command(command) do
    [cmd | args] = String.split(command)
    {cmd, args}
  end

  @spec execute_command({String.t(), [String.t()]}) :: {Collectable.t(), non_neg_integer()}
  defp execute_command({cmd, args}) do
    System.cmd(cmd, args, into: IO.stream(:stdio, :line))
  end

  @spec handle_test_result({Collectable.t(), non_neg_integer()}) ::
          :ok | {:error, String.t()}
  defp handle_test_result({_output, 0}) do
    Prompter.success("All tests passed!")
    :ok
  end

  defp handle_test_result({_output, _code}), do: {:error, "Test suite failed"}

  @spec maybe_git_operations(Version.t()) :: :ok | {:error, String.t()}
  defp maybe_git_operations(version) do
    Prompter.section("Git Operations")

    if Git.git_repo?() do
      prompt_git_operations(version)
    else
      skip_git_operations()
    end
  end

  @spec skip_git_operations() :: :ok
  defp skip_git_operations do
    Prompter.info("Not a git repository, skipping git operations")
    :ok
  end

  @spec prompt_git_operations(Version.t()) :: :ok | {:error, String.t()}
  defp prompt_git_operations(version) do
    if Prompter.confirm("Commit changes and create git tag?") do
      perform_git_operations(version)
    else
      skip_git_commit()
    end
  end

  @spec skip_git_commit() :: :ok
  defp skip_git_commit do
    Prompter.info("Skipping git operations")
    :ok
  end

  @spec perform_git_operations(Version.t()) :: :ok | {:error, String.t()}
  defp perform_git_operations(version) do
    with :ok <- stage_changes(),
         :ok <- commit_changes(version),
         :ok <- create_tag(version) do
      maybe_push()
    end
  end

  @spec stage_changes() :: :ok | {:error, String.t()}
  defp stage_changes do
    Prompter.info("Staging changes...")
    Git.stage_all()
  end

  @spec commit_changes(Version.t()) :: :ok | {:error, String.t()}
  defp commit_changes(version) do
    Prompter.info("Committing...")
    Git.commit(version)
  end

  @spec create_tag(Version.t()) :: :ok | {:error, String.t()}
  defp create_tag(version) do
    Prompter.info("Creating tag...")

    version
    |> Git.create_tag()
    |> handle_tag_creation(version)
  end

  @spec handle_tag_creation(:ok | {:error, String.t()}, Version.t()) ::
          :ok | {:error, String.t()}
  defp handle_tag_creation(:ok, version) do
    Prompter.success("Created tag v#{Version.to_string(version)}")
    :ok
  end

  defp handle_tag_creation(error, _version), do: error

  @spec maybe_push() :: :ok | {:error, String.t()}
  defp maybe_push do
    if Prompter.confirm("Push to origin?") do
      push_to_origin()
    else
      skip_push()
    end
  end

  @spec skip_push() :: :ok
  defp skip_push do
    Prompter.info("Skipping push")
    :ok
  end

  @spec push_to_origin() :: :ok | {:error, String.t()}
  defp push_to_origin do
    Prompter.info("Pushing to origin...")

    with {:ok, branch} <- Git.current_branch(),
         :ok <- Git.push(branch) do
      Prompter.success("Pushed to origin")
      :ok
    end
  end

  @spec show_completion_message() :: :ok
  defp show_completion_message do
    Prompter.section("Hex Publishing")
    Prompter.info("To publish to Hex.pm, run:")
    Prompter.info("  mix hex.publish")
    Prompter.info("")
    Prompter.success("Release process complete!")
  end

  @spec handle_error(String.t()) :: no_return()
  defp handle_error(reason) do
    Prompter.error("Release failed: #{reason}")
    Mix.raise("Release aborted")
  end

  @spec handle_abort() :: :ok
  defp handle_abort do
    Prompter.info("Release aborted by user")
  end

  @spec show_help() :: :ok
  defp show_help do
    IO.puts("""
    Usage: mix version <bump_type>

    Bump types:
      patch - Bump patch version (0.0.x)
      minor - Bump minor version (0.x.0)
      major - Bump major version (x.0.0)

    Examples:
      mix version patch   # 1.0.0 -> 1.0.1
      mix version minor   # 1.0.0 -> 1.1.0
      mix version major   # 1.0.0 -> 2.0.0
    """)
  end
end