defmodule Mix.Tasks.Compile.DomoCompiler do
  @moduledoc false

  use Mix.Task.Compiler

  alias Domo.TypeEnsurerFactory.Alias
  alias Domo.TypeEnsurerFactory.Cleaner
  alias Domo.TypeEnsurerFactory.DependencyResolver
  alias Domo.TypeEnsurerFactory.Generator
  alias Domo.TypeEnsurerFactory.Error
  alias Domo.TypeEnsurerFactory.ResolvePlanner
  alias Domo.TypeEnsurerFactory.Resolver
  alias Domo.MixProjectHelper
  alias Mix.Task.Compiler.Diagnostic

  @recursive true
  @plan_manifest "type_resolving_plan.domo"
  @types_manifest "resolved_types.domo"
  @deps_manifest "modules_deps.domo"
  @generated_code_directory "/domo_generated_code"

  @impl true
  def run(args) do
    project = MixProjectHelper.global_stub() || Mix.Project
    plan_path = manifest_path(project, :plan)
    types_path = manifest_path(project, :types)
    deps_path = manifest_path(project, :deps)
    code_path = generated_code_path(project)

    prev_ignore_module_conflict = Map.get(Code.compiler_options(), :ignore_module_conflict, false)
    Code.compiler_options(ignore_module_conflict: true)

    paths = {plan_path, types_path, deps_path, code_path}
    verbose? = Enum.member?(args, "--verbose")
    result = build_ensurer_modules(paths, verbose?)

    Code.compiler_options(ignore_module_conflict: prev_ignore_module_conflict)

    maybe_print_errors(result)

    result
  end

  def generated_code_path(mix_project) do
    Path.join(mix_project.build_path(), @generated_code_directory)
  end

  defp build_ensurer_modules(paths, verbose?) do
    {plan_path, types_path, deps_path, code_path} = paths

    Cleaner.rmdir_if_exists!(code_path)

    stop_and_flush_planner(plan_path, verbose?)

    with {:ok, {_modules, deps_warns}} <- recompile_depending_structs(deps_path),
         stop_and_flush_planner(plan_path, verbose?),
         :ok <- resolve_types(plan_path, types_path, deps_path),
         {:ok, type_ensurer_paths} <- generate_type_ensurers(types_path, code_path),
         {:ok, {modules, ens_warns}} <- compile_type_ensurers(type_ensurer_paths, verbose?) do
      Cleaner.rm!([plan_path, types_path])

      result = if(Enum.empty?(modules), do: :noop, else: :ok)
      warnings = format_warnings([deps_warns, ens_warns])
      {result, warnings}
    else
      {:error, {source, message}} ->
        case message do
          [%Error{compiler_module: Resolver, message: :no_plan}] -> {:noop, []}
          {ex_errors, _ex_warns} -> {:error, Enum.map(ex_errors, &diagnostic(source, &1))}
          errors when is_list(errors) -> {:error, Enum.map(errors, &diagnostic(&1))}
          error -> {:error, [diagnostic(error)]}
        end
    end
  end

  defp stop_and_flush_planner(plan_path, verbose?) do
    ResolvePlanner.ensure_flushed_and_stopped(plan_path, verbose?)
  end

  defp recompile_depending_structs(deps_path) do
    case DependencyResolver.maybe_recompile_depending_structs(deps_path) do
      {:ok, modules, warnings} -> {:ok, {modules, warnings}}
      {:error, ex_errors, ex_warnings} -> {:error, {:deps, {ex_errors, ex_warnings}}}
      {:error, message} -> {:error, {:deps, message}}
    end
  end

  defp resolve_types(plan_path, types_path, deps_path) do
    case Resolver.resolve(plan_path, types_path, deps_path) do
      :ok -> :ok
      {:error, message} -> {:error, {:resolve, message}}
    end
  end

  defp generate_type_ensurers(types_path, code_path) do
    case Generator.generate(types_path, code_path) do
      {:ok, _type_ensurer_paths} = ok -> ok
      {:error, message} -> {:error, {:generate, message}}
    end
  end

  defp compile_type_ensurers(type_ensurer_paths, verbose?) do
    if verbose? do
      IO.write("Compile generated type ensurers:\n")
      Enum.each(type_ensurer_paths, &IO.write("  #{&1}\n"))
    end

    case Generator.compile(type_ensurer_paths) do
      {:ok, modules, te_warns} -> {:ok, {modules, te_warns}}
      {:error, ex_errors, ex_warnings} -> {:error, {:compile, {ex_errors, ex_warnings}}}
      {:error, message} -> {:error, {:compile, message}}
    end
  end

  defp format_warnings(warns) do
    warns
    |> List.flatten()
    |> Enum.map(fn {path, position, message} ->
      %Diagnostic{
        compiler_name: "elixir",
        file: path,
        position: position,
        message: message,
        severity: :warning
      }
    end)
  end

  defp diagnostic(%Error{compiler_module: Resolver, struct_module: nil} = error) do
    message = """
    #{module_to_string(error.compiler_module)} failed due to #{inspect(error.message)}.\
    """

    diagnostic(error.file, message)
  end

  defp diagnostic(%Error{compiler_module: Resolver} = error) do
    message = """
    #{module_to_string(error.compiler_module)} failed to resolve fields type \
    of the #{module_to_string(error.struct_module)} struct due to #{inspect(error.message)}.\
    """

    diagnostic(error.file, message)
  end

  defp diagnostic(%Error{compiler_module: Generator} = error) do
    message = """
    #{module_to_string(error.compiler_module)} failed to generate \
    TypeEnsurer module code due to #{inspect(error.message)}.\
    """

    diagnostic(error.file, message)
  end

  defp diagnostic(:deps, {path, _line, error}) do
    message = """
    Elixir compiler launched by DependencyResolver failed due to \
    #{error}\
    """

    diagnostic(path, message)
  end

  defp diagnostic(:compile, {path, _line, error}) do
    message = """
    Elixir compiler failed to compile a TypeEnsurer module code due to \
    #{error}\
    """

    diagnostic(path, message)
  end

  defp diagnostic(file, message) do
    %Diagnostic{
      compiler_name: "domo",
      file: file,
      message: message,
      position: 1,
      severity: :error
    }
  end

  defp module_to_string(module) do
    {:__aliases__, [alias: false], module_parts} = Alias.atom_to_alias(module)

    module_parts
    |> Enum.map(&Atom.to_string(&1))
    |> Enum.join(".")
  end

  defp maybe_print_errors({:error, diagnostics}) do
    diagnostics
    |> List.wrap()
    |> Enum.each(&print_error(&1.file, &1.message))
  end

  defp maybe_print_errors(_), do: nil

  defp print_error(file, reason) do
    IO.write([
      "\n== Type ensurer compilation error in file #{Path.relative_to_cwd(file)} ==\n",
      ["** ", reason, ?\n]
    ])
  end

  @impl true
  def manifests, do: [@plan_manifest, @types_manifest]
  def deps_manifest, do: @deps_manifest

  def manifest_path(mix_project, manifest_kind) do
    Path.join(mix_project.build_path(), manifest(manifest_kind))
  end

  defp manifest(kind) do
    case kind do
      :plan -> @plan_manifest
      :types -> @types_manifest
      :deps -> @deps_manifest
    end
  end

  @impl true
  def clean do
    project = MixProjectHelper.global_stub() || Mix.Project
    plan_path = manifest_path(project, :plan)
    types_path = manifest_path(project, :types)
    deps_path = manifest_path(project, :deps)
    code_path = generated_code_path(project)

    File.rm(plan_path)
    File.rm(types_path)
    File.rm(deps_path)
    Cleaner.rmdir_if_exists!(code_path)
  end
end