defmodule Codex.Options do
  @moduledoc """
  Global configuration for Codex interactions.

  Options are built from caller-supplied values merged with environment defaults.

  ## Models newer than the bundled registry

  `Codex.Models` resolves model metadata from a bundled, vendored catalog
  (via `CliSubprocessCore.ModelRegistry`). A model id that's newer than the
  bundled catalog is passed through as-is by default — matching the
  installed `codex` CLI, which does not itself validate `--model` against
  this catalog. A warning is logged when this happens. Pass
  `allow_unknown_model: false` to restore strict rejection of any model id
  not present in the bundled catalog (useful for catching typos early).
  """

  require Logger

  alias CliSubprocessCore.{CommandSpec, ExecutionSurface, ModelInput, ProviderCLI}
  alias Codex.Auth
  alias Codex.Config.BaseURL
  alias Codex.Config.OptionNormalizers
  alias Codex.Config.Overrides
  alias Codex.GovernedAuthority
  alias Codex.Models

  @derive {Inspect, except: [:api_key]}
  @enforce_keys []
  defstruct api_key: nil,
            base_url: BaseURL.default(),
            codex_path_override: nil,
            execution_surface: %ExecutionSurface{},
            telemetry_prefix: [:codex],
            model_payload: nil,
            model: Models.default_model(),
            reasoning_effort: Models.default_reasoning_effort(),
            model_personality: nil,
            model_reasoning_summary: nil,
            model_verbosity: nil,
            model_context_window: nil,
            model_supports_reasoning_summaries: nil,
            model_auto_compact_token_limit: nil,
            review_model: nil,
            history_persistence: nil,
            history_max_bytes: nil,
            hide_agent_reasoning: false,
            tool_output_token_limit: nil,
            agent_max_threads: nil,
            config_overrides: [],
            governed_authority: nil,
            allow_unknown_model: true

  @typep config_override_value_scalar :: String.t() | boolean() | integer() | float()
  @typep config_override_value ::
           config_override_value_scalar()
           | [config_override_value()]
           | %{optional(String.t() | atom()) => config_override_value()}

  @type t :: %__MODULE__{
          api_key: String.t() | nil,
          base_url: String.t(),
          codex_path_override: String.t() | nil,
          execution_surface: ExecutionSurface.t(),
          telemetry_prefix: [atom()],
          model_payload: CliSubprocessCore.ModelRegistry.selection() | nil,
          model: String.t() | nil,
          reasoning_effort: Models.reasoning_effort() | nil,
          model_personality: Codex.Protocol.ConfigTypes.personality() | nil,
          model_reasoning_summary: String.t() | nil,
          model_verbosity: String.t() | nil,
          model_context_window: pos_integer() | nil,
          model_supports_reasoning_summaries: boolean() | nil,
          model_auto_compact_token_limit: pos_integer() | nil,
          review_model: String.t() | nil,
          history_persistence: String.t() | nil,
          history_max_bytes: non_neg_integer() | nil,
          hide_agent_reasoning: boolean(),
          tool_output_token_limit: pos_integer() | nil,
          agent_max_threads: pos_integer() | nil,
          config_overrides: [
            String.t() | {String.t(), config_override_value()}
          ],
          governed_authority: map() | nil,
          allow_unknown_model: boolean()
        }

  @doc """
  Builds a validated options struct.

  API keys are optional. When omitted, the Codex CLI relies on your existing
  `codex` login (ChatGPT tokens stored in `auth.json`).
  """
  @spec new(map() | keyword()) :: {:ok, t()} | {:error, term()}
  def new(attrs \\ %{}) do
    attrs = Map.new(attrs)

    with {:ok, governed_authority} <- fetch_governed_authority(attrs),
         {:ok, api_key} <- fetch_api_key(attrs, governed_authority),
         {:ok, base_url} <- fetch_base_url(attrs, governed_authority),
         {:ok, override} <- fetch_codex_path_override(attrs),
         {:ok, execution_surface} <- fetch_execution_surface(attrs),
         {:ok, telemetry_prefix} <- fetch_telemetry_prefix(attrs),
         {:ok, allow_unknown_model} <- fetch_allow_unknown_model(attrs),
         {:ok, model_input} <-
           normalize_model_input(attrs, governed_authority, allow_unknown_model),
         model_payload = model_input.selection,
         :ok = warn_if_unregistered_model(model_payload),
         normalized_attrs = model_input.attrs,
         {:ok, model} <- fetch_model(model_payload),
         {:ok, reasoning_effort} <- fetch_reasoning_effort(model_payload),
         {:ok, model_personality} <- fetch_model_personality(normalized_attrs),
         {:ok, reasoning_summary} <- fetch_reasoning_summary(normalized_attrs),
         {:ok, model_verbosity} <- fetch_model_verbosity(normalized_attrs),
         {:ok, model_context_window} <- fetch_model_context_window(normalized_attrs),
         {:ok, supports_reasoning_summaries} <-
           fetch_supports_reasoning_summaries(normalized_attrs),
         {:ok, model_auto_compact_token_limit} <-
           fetch_model_auto_compact_token_limit(normalized_attrs),
         {:ok, review_model} <- fetch_review_model(normalized_attrs),
         {:ok, history_persistence} <- fetch_history_persistence(normalized_attrs),
         {:ok, history_max_bytes} <- fetch_history_max_bytes(normalized_attrs),
         {:ok, hide_agent_reasoning} <- fetch_hide_agent_reasoning(normalized_attrs),
         {:ok, tool_output_token_limit} <- fetch_tool_output_token_limit(normalized_attrs),
         {:ok, agent_max_threads} <- fetch_agent_max_threads(normalized_attrs),
         {:ok, config_overrides} <- fetch_config_overrides(normalized_attrs),
         :ok <-
           GovernedAuthority.reject_config_overrides(
             governed_authority,
             config_overrides,
             :options
           ),
         :ok <-
           GovernedAuthority.validate_command_override(
             governed_authority,
             override,
             :options
           ) do
      {:ok,
       %__MODULE__{
         api_key: api_key,
         base_url: base_url,
         codex_path_override: override,
         execution_surface: execution_surface,
         telemetry_prefix: telemetry_prefix,
         model_payload: model_payload,
         model: model,
         reasoning_effort: reasoning_effort,
         model_personality: model_personality,
         model_reasoning_summary: reasoning_summary,
         model_verbosity: model_verbosity,
         model_context_window: model_context_window,
         model_supports_reasoning_summaries: supports_reasoning_summaries,
         model_auto_compact_token_limit: model_auto_compact_token_limit,
         review_model: review_model,
         history_persistence: history_persistence,
         history_max_bytes: history_max_bytes,
         hide_agent_reasoning: hide_agent_reasoning,
         tool_output_token_limit: tool_output_token_limit,
         agent_max_threads: agent_max_threads,
         config_overrides: config_overrides,
         governed_authority: governed_authority,
         allow_unknown_model: allow_unknown_model
       }}
    end
  end

  @doc """
  Determines a stable command spec for launching `codex`.

  Local execution surfaces honor the shared core discovery policy:

  1. Explicit override on the struct.
  2. `CODEX_PATH`.
  3. Shared local discovery through `CliSubprocessCore.ProviderCLI`.

  Remote execution surfaces intentionally avoid local-path discovery. They use
  an explicit override when supplied, otherwise they fall back to the remote
  provider command name (`codex`).
  """
  @spec codex_command_spec(t(), ExecutionSurface.t() | map() | keyword() | nil) ::
          {:ok, CommandSpec.t()} | {:error, term()}
  def codex_command_spec(%__MODULE__{} = opts, execution_surface_override \\ nil) do
    with {:ok, execution_surface} <-
           effective_command_execution_surface(opts, execution_surface_override) do
      resolve_codex_command_spec(opts, execution_surface)
    end
  end

  defp resolve_codex_command_spec(
         %__MODULE__{codex_path_override: override},
         %ExecutionSurface{} = execution_surface
       )
       when is_binary(override) do
    resolve_provider_cli([command: override], execution_surface)
  end

  defp resolve_codex_command_spec(%__MODULE__{}, %ExecutionSurface{} = execution_surface) do
    resolve_provider_cli([], execution_surface)
  end

  defp resolve_provider_cli(provider_opts, %ExecutionSurface{} = execution_surface)
       when is_list(provider_opts) do
    case ProviderCLI.resolve(:codex, provider_opts, execution_surface: execution_surface) do
      {:ok, %CommandSpec{} = spec} ->
        {:ok, spec}

      {:error, %ProviderCLI.Error{kind: :cli_not_found}} ->
        {:error, :codex_binary_not_found}

      {:error, reason} ->
        {:error, reason}
    end
  end

  @doc """
  Determines the stable executable path to `codex`.

  This returns the resolved program from `codex_command_spec/1`. Internal
  launchers should prefer `codex_command_spec/1` so argv prefixes remain
  available when needed.
  """
  @spec codex_path(t()) :: {:ok, String.t()} | {:error, term()}
  def codex_path(%__MODULE__{} = opts) do
    with {:ok, %CommandSpec{program: program}} <- codex_command_spec(opts) do
      {:ok, program}
    end
  end

  @doc false
  @spec execution_model(t()) :: String.t() | nil
  def execution_model(%__MODULE__{model: model} = opts) when is_binary(model) and model != "" do
    if implicit_default_model?(opts), do: nil, else: model
  end

  def execution_model(%__MODULE__{}), do: nil

  @doc false
  @spec normalize_execution_surface(term()) :: {:ok, ExecutionSurface.t()} | {:error, term()}
  def normalize_execution_surface(nil), do: {:ok, %ExecutionSurface{}}

  def normalize_execution_surface(%ExecutionSurface{} = execution_surface),
    do: {:ok, execution_surface}

  def normalize_execution_surface(execution_surface) when is_list(execution_surface) do
    ExecutionSurface.new(execution_surface)
  end

  def normalize_execution_surface(%{} = execution_surface) do
    execution_surface
    |> execution_surface_attrs()
    |> ExecutionSurface.new()
  end

  def normalize_execution_surface(other), do: {:error, {:invalid_execution_surface, other}}

  @doc false
  @spec execution_surface_options(t() | ExecutionSurface.t() | nil) :: keyword()
  def execution_surface_options(%__MODULE__{execution_surface: execution_surface}) do
    execution_surface_options(execution_surface)
  end

  def execution_surface_options(%ExecutionSurface{} = execution_surface) do
    execution_surface
    |> ExecutionSurface.surface_metadata()
    |> Keyword.put(:transport_options, execution_surface.transport_options)
  end

  def execution_surface_options(nil), do: []

  defp fetch_governed_authority(attrs), do: GovernedAuthority.fetch(attrs)

  defp fetch_api_key(attrs, nil) do
    case normalize_string(pick(attrs, [:api_key, "api_key"], Auth.api_key())) do
      nil -> {:ok, nil}
      key -> {:ok, key}
    end
  end

  defp fetch_api_key(attrs, %{} = _governed_authority) do
    case normalize_string(pick(attrs, [:api_key, "api_key"])) do
      nil -> {:ok, nil}
      key -> {:ok, key}
    end
  end

  defp fetch_base_url(attrs, nil) do
    case BaseURL.resolve(attrs) do
      url when is_binary(url) and url != "" -> {:ok, url}
      _ -> {:error, :invalid_base_url}
    end
  end

  defp fetch_base_url(attrs, %{} = _governed_authority) do
    case BaseURL.resolve_explicit(attrs) || BaseURL.default() do
      url when is_binary(url) and url != "" -> {:ok, url}
      _ -> {:error, :invalid_base_url}
    end
  end

  defp fetch_codex_path_override(attrs) do
    case pick(attrs, [:codex_path_override, "codex_path_override", :codex_path, "codex_path"]) do
      nil -> {:ok, nil}
      "" -> {:error, :invalid_codex_path}
      override -> {:ok, override}
    end
  end

  defp fetch_execution_surface(attrs) do
    attrs
    |> pick([:execution_surface, "execution_surface"])
    |> normalize_execution_surface()
  end

  defp fetch_telemetry_prefix(attrs) do
    case pick(attrs, [:telemetry_prefix, "telemetry_prefix"], [:codex]) do
      prefix when is_list(prefix) ->
        if Enum.all?(prefix, &is_atom/1) do
          {:ok, prefix}
        else
          {:error, {:invalid_telemetry_prefix, prefix}}
        end

      other ->
        {:error, {:invalid_telemetry_prefix, other}}
    end
  end

  defp effective_command_execution_surface(
         %__MODULE__{execution_surface: %ExecutionSurface{} = execution_surface},
         nil
       ),
       do: {:ok, execution_surface}

  defp effective_command_execution_surface(%__MODULE__{}, execution_surface_override),
    do: normalize_execution_surface(execution_surface_override)

  defp pick(attrs, keys, default \\ nil)

  defp pick(attrs, [key | rest], default) do
    case Map.get(attrs, key) do
      nil -> pick(attrs, rest, default)
      value -> value
    end
  end

  defp pick(_attrs, [], default), do: default

  defp implicit_default_model?(%__MODULE__{model_payload: payload}) when is_map(payload) do
    case Map.get(payload, :resolution_source, Map.get(payload, "resolution_source")) do
      value when value in [:default, "default"] -> true
      _ -> false
    end
  end

  defp implicit_default_model?(%__MODULE__{}), do: false

  defp normalize_model_input(attrs, nil, allow_unknown_model) do
    attrs
    |> apply_model_env_defaults()
    |> Map.put(:allow_unknown, allow_unknown_model)
    |> then(&ModelInput.normalize(:codex, &1, []))
  end

  defp normalize_model_input(attrs, %{} = _governed_authority, allow_unknown_model) do
    attrs
    |> Map.put(:allow_unknown, allow_unknown_model)
    |> then(&ModelInput.normalize(:codex, &1, []))
  end

  defp fetch_allow_unknown_model(attrs) do
    case pick(attrs, [:allow_unknown_model, "allow_unknown_model"]) do
      nil -> {:ok, true}
      value when is_boolean(value) -> {:ok, value}
      other -> {:error, {:invalid_allow_unknown_model, other}}
    end
  end

  defp warn_if_unregistered_model(%{extra: %{"unregistered" => true}} = payload) do
    Logger.warning(
      "Codex model #{inspect(Map.get(payload, :resolved_model))} is not in the bundled " <>
        "model registry; passing it through as-is. This is expected for a model newer " <>
        "than the bundled registry. Pass allow_unknown_model: false to require a " <>
        "registered model."
    )

    :ok
  end

  defp warn_if_unregistered_model(_payload), do: :ok

  defp apply_model_env_defaults(attrs) when is_map(attrs) do
    if explicit_model_payload?(attrs) do
      attrs
    else
      attrs
      |> put_missing_attr(
        :env_model,
        Codex.Env.get("CODEX_MODEL") ||
          Codex.Env.get("OPENAI_DEFAULT_MODEL") ||
          Codex.Env.get("CODEX_MODEL_DEFAULT")
      )
      |> put_missing_attr(:provider_backend, Codex.Env.get("CODEX_PROVIDER_BACKEND"))
      |> put_missing_attr(:oss_provider, Codex.Env.get("CODEX_OSS_PROVIDER"))
      |> put_missing_attr(:ollama_base_url, Codex.Env.get("CODEX_OLLAMA_BASE_URL"))
    end
  end

  defp explicit_model_payload?(attrs) when is_map(attrs) do
    case Map.get(attrs, :model_payload, Map.get(attrs, "model_payload")) do
      nil -> false
      _payload -> true
    end
  end

  defp execution_surface_attrs(attrs) when is_map(attrs) do
    [
      surface_kind: Map.get(attrs, :surface_kind, Map.get(attrs, "surface_kind")),
      transport_options: Map.get(attrs, :transport_options, Map.get(attrs, "transport_options")),
      target_id: Map.get(attrs, :target_id, Map.get(attrs, "target_id")),
      lease_ref: Map.get(attrs, :lease_ref, Map.get(attrs, "lease_ref")),
      surface_ref: Map.get(attrs, :surface_ref, Map.get(attrs, "surface_ref")),
      boundary_class: Map.get(attrs, :boundary_class, Map.get(attrs, "boundary_class")),
      observability: Map.get(attrs, :observability, Map.get(attrs, "observability", %{}))
    ]
  end

  defp put_missing_attr(attrs, _key, nil), do: attrs
  defp put_missing_attr(attrs, _key, ""), do: attrs

  defp put_missing_attr(attrs, key, value) when is_map(attrs) and is_atom(key) do
    cond do
      Map.has_key?(attrs, key) -> attrs
      Map.has_key?(attrs, Atom.to_string(key)) -> attrs
      true -> Map.put(attrs, key, value)
    end
  end

  defp fetch_model(model_payload) when is_map(model_payload) do
    {:ok, Map.get(model_payload, :resolved_model, Map.get(model_payload, "resolved_model"))}
  end

  defp fetch_reasoning_effort(model_payload) when is_map(model_payload) do
    reasoning =
      Map.get(model_payload, :reasoning, Map.get(model_payload, "reasoning"))

    Models.normalize_reasoning_effort(reasoning)
  end

  defp fetch_model_personality(attrs) do
    attrs
    |> pick([:model_personality, "model_personality", :personality, "personality"])
    |> normalize_personality()
  end

  defp fetch_reasoning_summary(attrs) do
    attrs
    |> pick([
      :model_reasoning_summary,
      "model_reasoning_summary",
      :reasoning_summary,
      "reasoning_summary"
    ])
    |> normalize_reasoning_summary()
  end

  defp fetch_model_verbosity(attrs) do
    attrs
    |> pick([:model_verbosity, "model_verbosity", :verbosity, "verbosity"])
    |> normalize_model_verbosity()
  end

  defp fetch_model_context_window(attrs) do
    case pick(attrs, [
           :model_context_window,
           "model_context_window",
           :context_window,
           "context_window"
         ]) do
      nil -> {:ok, nil}
      value when is_integer(value) and value > 0 -> {:ok, value}
      other -> {:error, {:invalid_model_context_window, other}}
    end
  end

  defp fetch_supports_reasoning_summaries(attrs) do
    case pick(
           attrs,
           [
             :model_supports_reasoning_summaries,
             "model_supports_reasoning_summaries",
             :supports_reasoning_summaries,
             "supports_reasoning_summaries"
           ]
         ) do
      nil -> {:ok, nil}
      value when is_boolean(value) -> {:ok, value}
      other -> {:error, {:invalid_model_supports_reasoning_summaries, other}}
    end
  end

  defp fetch_model_auto_compact_token_limit(attrs) do
    case pick(attrs, [
           :model_auto_compact_token_limit,
           "model_auto_compact_token_limit",
           :auto_compact_token_limit,
           "auto_compact_token_limit"
         ]) do
      nil -> {:ok, nil}
      value when is_integer(value) and value > 0 -> {:ok, value}
      other -> {:error, {:invalid_model_auto_compact_token_limit, other}}
    end
  end

  defp fetch_review_model(attrs) do
    case pick(attrs, [:review_model, "review_model"]) do
      nil -> {:ok, nil}
      "" -> {:ok, nil}
      value when is_binary(value) -> {:ok, value}
      other -> {:error, {:invalid_review_model, other}}
    end
  end

  defp fetch_history_persistence(attrs) do
    history = pick(attrs, [:history, "history"])

    value =
      pick(attrs, [:history_persistence, "history_persistence"]) ||
        if is_map(history) do
          Map.get(history, :persistence, Map.get(history, "persistence"))
        end

    normalize_history_persistence(value)
  end

  defp fetch_history_max_bytes(attrs) do
    history = pick(attrs, [:history, "history"])

    value =
      pick(attrs, [:history_max_bytes, "history_max_bytes"]) ||
        if is_map(history) do
          Map.get(
            history,
            :max_bytes,
            Map.get(history, "max_bytes", Map.get(history, "maxBytes"))
          )
        end

    validate_history_max_bytes(value)
  end

  defp fetch_hide_agent_reasoning(attrs) do
    case pick(attrs, [:hide_agent_reasoning, "hide_agent_reasoning"]) do
      nil -> {:ok, false}
      value when is_boolean(value) -> {:ok, value}
      other -> {:error, {:invalid_hide_agent_reasoning, other}}
    end
  end

  defp fetch_tool_output_token_limit(attrs) do
    case pick(attrs, [
           :tool_output_token_limit,
           "tool_output_token_limit",
           :tool_output_limit,
           "tool_output_limit"
         ]) do
      nil -> {:ok, nil}
      value when is_integer(value) and value > 0 -> {:ok, value}
      other -> {:error, {:invalid_tool_output_token_limit, other}}
    end
  end

  defp fetch_agent_max_threads(attrs) do
    case pick(attrs, [
           :agent_max_threads,
           "agent_max_threads",
           :max_threads,
           "max_threads"
         ]) do
      nil -> {:ok, nil}
      value when is_integer(value) and value > 0 -> {:ok, value}
      other -> {:error, {:invalid_agent_max_threads, other}}
    end
  end

  defp fetch_config_overrides(attrs) do
    attrs
    |> pick([:config_overrides, "config_overrides", :config, "config"], [])
    |> Overrides.normalize_config_overrides()
  end

  defp normalize_string(nil), do: nil

  defp normalize_string(value) when is_binary(value) do
    value = String.trim(value)
    if value == "", do: nil, else: value
  end

  defp normalize_string(_), do: nil

  defp normalize_reasoning_summary(value),
    do: OptionNormalizers.normalize_reasoning_summary(value, :invalid_model_reasoning_summary)

  defp normalize_history_persistence(value),
    do: OptionNormalizers.normalize_history_persistence(value, :invalid_history_persistence)

  defp validate_history_max_bytes(nil), do: {:ok, nil}

  defp validate_history_max_bytes(value) when is_integer(value) and value >= 0, do: {:ok, value}

  defp validate_history_max_bytes(other),
    do: {:error, {:invalid_history_max_bytes, other}}

  defp normalize_model_verbosity(value),
    do: OptionNormalizers.normalize_model_verbosity(value, :invalid_model_verbosity)

  defp normalize_personality(nil), do: {:ok, nil}

  defp normalize_personality(value) when is_atom(value) do
    value
    |> Atom.to_string()
    |> normalize_personality()
  end

  defp normalize_personality(value) when is_binary(value) do
    case String.downcase(String.trim(value)) do
      "" -> {:ok, nil}
      "friendly" -> {:ok, :friendly}
      "pragmatic" -> {:ok, :pragmatic}
      "none" -> {:ok, :none}
      other -> {:error, {:invalid_model_personality, other}}
    end
  end

  defp normalize_personality(other), do: {:error, {:invalid_model_personality, other}}
end