defmodule Mix.Tasks.ZenQuant.Manifest do
  @shortdoc "Export ZenQuant API manifest as JSON"

  @moduledoc """
  Exports the ZenQuant API manifest as a static JSON file.

  The manifest describes all ZenQuant modules and their public functions,
  including typespecs, documentation hints, and parameter metadata.
  Non-BEAM consumers (CI pipelines, other languages, EIP-8004 registration)
  can use this artifact to discover ZenQuant's capabilities.

  ## Usage

      mix zen_quant.manifest
      mix zen_quant.manifest --output /tmp/manifest.json

  """

  use Mix.Task

  @default_output "api_manifest.json"

  @doc false
  @impl Mix.Task
  def run(args) do
    Mix.Task.run("app.start")
    {opts, _rest} = OptionParser.parse!(args, strict: [output: :string])
    output_path = opts[:output] || @default_output

    manifest = ZenQuant.Manifest.build()
    json = manifest |> json_safe() |> JSON.encode!()

    File.write!(output_path, json)

    module_count = length(manifest[:modules])
    func_count = Enum.sum_by(manifest[:modules], &length(&1[:functions]))

    Mix.shell().info("Wrote #{output_path} (#{module_count} modules, #{func_count} functions)")
  end

  defp json_safe(%_{} = value), do: value

  defp json_safe(value) when is_map(value) do
    Map.new(value, fn {key, val} -> {key, json_safe(val)} end)
  end

  defp json_safe(value) when is_list(value), do: Enum.map(value, &json_safe/1)
  defp json_safe(value) when is_tuple(value), do: value |> Tuple.to_list() |> Enum.map(&json_safe/1)
  defp json_safe(value), do: value
end