-- modified version of:
-- https://github.com/vijaymarupudi/nvim-fzf/blob/master/lua/fzf/actions.lua
local uv = vim.loop
local path = require "fzf-lua.path"
local libuv = require "fzf-lua.libuv"

local M = {}

local _counter = 0
local _registry = {}

function M.register_func(fn)
  _counter = _counter + 1
  _registry[_counter] = fn
  return _counter
end

function M.get_func(counter)
  return _registry[counter]
end

-- creates a new address to listen to messages from actions. This is important,
-- if the user is using a custom fixed $NVIM_LISTEN_ADDRESS. Different neovim
-- instances will then use the same path as the address and it causes a mess,
-- i.e. actions stop working on the old instance. So we create our own (random
-- path) RPC server for this instance if it hasn't been started already.
-- NOT USED ANYMORE, we use `vim.g.fzf_lua_server` instead
-- local action_server_address = nil

function M.raw_async_action(fn, fzf_field_expression, debug)

  if not fzf_field_expression then
    fzf_field_expression = "{+}"
  end

  local receiving_function = function(pipe_path, ...)
    local pipe = uv.new_pipe(false)
    local args = {...}
    uv.pipe_connect(pipe, pipe_path, function(err)
      vim.schedule(function ()
        fn(pipe, unpack(args))
      end)
    end)
  end

  local id = M.register_func(receiving_function)

  -- this is for windows WSL and AppImage users, their nvim path isn't just
  -- 'nvim', it can be something else
  local nvim_bin = vim.v.argv[1]

  local call_args = ("fzf_lua_server=[[%s]], fnc_id=%d %s"):format(
    vim.g.fzf_lua_server, id, debug and ", debug=true" or "")

  local action_cmd = ("%s -n --headless --clean --cmd %s %s"):format(
    libuv.shellescape(nvim_bin),
    libuv.shellescape(("lua loadfile([[%s]])().rpc_nvim_exec_lua({%s})")
      :format(path.join{vim.g.fzf_lua_directory, "shell_helper.lua"}, call_args)),
    fzf_field_expression)

  return action_cmd, id
end

function M.async_action(fn, fzf_field_expression, debug)
  local action_string, id = M.raw_async_action(fn, fzf_field_expression, debug)
  return vim.fn.shellescape(action_string), id
end

function M.raw_action(fn, fzf_field_expression, debug)

  local receiving_function = function(pipe, ...)
    local ret = fn(...)

    local on_complete = function(_)
      -- We are NOT asserting, in case fzf closes
      -- the pipe before we can send the preview
      -- assert(not err)
      uv.close(pipe)
    end

    if type(ret) == "string" then
      uv.write(pipe, ret, on_complete)
    elseif type(ret) == nil then
      on_complete()
    elseif type(ret) == "table" then
      if not vim.tbl_isempty(ret) then
        uv.write(pipe, vim.tbl_map(function(x) return x.."\n" end, ret), on_complete)
      else
        on_complete()
      end
    else
      uv.write(pipe, tostring(ret) .. "\n", on_complete)
    end
  end

  return M.raw_async_action(receiving_function, fzf_field_expression, debug)
end

function M.action(fn, fzf_field_expression ,debug)
  local action_string, id = M.raw_action(fn, fzf_field_expression, debug)
  return vim.fn.shellescape(action_string), id
end

M.preview_action_cmd = function(fn, fzf_field_expression, debug)

  return M.async_action(function(pipe, ...)

    local function on_finish(_, _)
      if pipe and not uv.is_closing(pipe) then
        uv.close(pipe)
        pipe = nil
      end
    end

    local function on_write(data, cb)
      if not pipe then
        cb(true)
      else
        uv.write(pipe, data, cb)
      end
    end

    return libuv.spawn({
        cmd = fn(...),
        cb_finish = on_finish,
        cb_write = on_write,
      }, false)

  end, fzf_field_expression, debug)
end

M.reload_action_cmd = function(opts, fzf_field_expression)

  local _pid = nil

  return M.raw_async_action(function(pipe, args)

    local function on_pid(pid)
      _pid = pid
      if opts.pid_cb then
        opts.pid_cb(pid)
      end
    end

    local function on_finish(_, _)
      if pipe and not uv.is_closing(pipe) then
        uv.close(pipe)
        pipe = nil
      end
    end

    local function on_write(data, cb)
      if not pipe then
        cb(true)
      else
        uv.write(pipe, data, cb)
      end
    end

    -- terminate previously running commands
    libuv.process_kill(_pid)

    -- return libuv.spawn({
    return libuv.async_spawn({
        cwd = opts.cwd,
        cmd = opts._reload_command(args[1]),
        cb_finish = on_finish,
        cb_write = on_write,
        cb_pid = on_pid,
        -- must send false, 'coroutinify' adds callback as last argument
        -- which will conflict with the 'fn_transform' argument
      }, opts._fn_transform or false)

  end, fzf_field_expression, opts.debug)
end

return M