-- |Interpreters for 'Settings'
module Ribosome.Interpreter.Settings where

import Exon (exon)

import Ribosome.Data.PluginName (PluginName (PluginName))
import Ribosome.Data.Setting (Setting (Setting))
import qualified Ribosome.Data.SettingError as SettingError
import Ribosome.Data.SettingError (SettingError)
import Ribosome.Effect.Settings (Settings (Get, Update))
import Ribosome.Host.Api.Effect (nvimGetVar, nvimSetVar)
import Ribosome.Host.Class.Msgpack.Decode (MsgpackDecode)
import qualified Ribosome.Host.Data.RpcError as RpcError
import Ribosome.Host.Data.RpcError (RpcError)
import Ribosome.Host.Effect.Rpc (Rpc)
import Ribosome.PluginName (pluginName)

-- |Assemble the name of a setting variable by prefixing the 'Setting' key with the plugin name if the flag is set.
settingVariableName ::
  Member (Reader PluginName) r =>
  Setting a ->
  Sem r Text
settingVariableName = \case
  Setting key False _ ->
    pure key
  Setting key True _ -> do
    PluginName name <- pluginName
    pure [exon|#{name}_#{key}|]

-- |Fetch the value for a setting stored in its Neovim variable.
settingRaw ::
  Members [Rpc, Reader PluginName] r =>
  MsgpackDecode a =>
  Setting a ->
  Sem r a
settingRaw s =
  nvimGetVar =<< settingVariableName s

-- |Return the default value for a setting or stop with an error if none is set.
fallback ::
  Members [Reader PluginName, Stop SettingError] r =>
  Setting a ->
  Sem r a
fallback = \case
  Setting _ _ (Just a) ->
    pure a
  s@(Setting _ _ Nothing) -> do
    n <- settingVariableName s
    stop (SettingError.Unset n)

-- |Interpret 'Settings' natively, using Neovim variables.
interpretSettingsRpc ::
  Members [Rpc !! RpcError, Reader PluginName] r =>
  InterpreterFor (Settings !! SettingError) r
interpretSettingsRpc =
  interpretResumable \case
    Get s ->
      settingRaw s !! \case
        RpcError.Decode e -> do
          n <- settingVariableName s
          stop (SettingError.Decode n e)
        RpcError.Api _ _ _ ->
          fallback s
        RpcError.Unexpected _ ->
          fallback s
    Update s a -> do
      n <- settingVariableName s
      resumeHoist (SettingError.UpdateFailed n) (nvimSetVar n a)