local plugin_loader = {}

local utils = require "lvim.utils"
local Log = require "lvim.core.log"
local join_paths = utils.join_paths
local in_headless = #vim.api.nvim_list_uis() == 0

-- we need to reuse this outside of init()
local compile_path = join_paths(get_config_dir(), "plugin", "packer_compiled.lua")
local snapshot_path = join_paths(get_cache_dir(), "snapshots")
local default_snapshot = join_paths(get_lvim_base_dir(), "snapshots", "default.json")

function plugin_loader.init(opts)
  opts = opts or {}

  local install_path = opts.install_path
    or join_paths(vim.fn.stdpath "data", "site", "pack", "packer", "start", "packer.nvim")

  local init_opts = {
    package_root = opts.package_root or join_paths(vim.fn.stdpath "data", "site", "pack"),
    compile_path = compile_path,
    snapshot_path = snapshot_path,
    max_jobs = 40,
    log = { level = "warn" },
    git = {
      clone_timeout = 300,
    },
    display = {
      open_fn = function()
        return require("packer.util").float { border = "rounded" }
      end,
    },
  }

  if in_headless then
    init_opts.display = nil
  end

  if not utils.is_directory(install_path) then
    vim.fn.system { "git", "clone", "--depth", "1", "https://github.com/wbthomason/packer.nvim", install_path }
    vim.cmd "packadd packer.nvim"
    -- IMPORTANT: we only set this the very first time to avoid constantly triggering the rollback function
    -- https://github.com/wbthomason/packer.nvim/blob/c576ab3f1488ee86d60fd340d01ade08dcabd256/lua/packer.lua#L998-L995
    init_opts.snapshot = default_snapshot
  end

  local status_ok, packer = pcall(require, "packer")
  if status_ok then
    packer.on_complete = vim.schedule_wrap(function()
      require("lvim.utils.hooks").run_on_packer_complete()
    end)
    packer.init(init_opts)
  end
end

-- packer expects a space separated list
local function pcall_packer_command(cmd, kwargs)
  local status_ok, msg = pcall(function()
    require("packer")[cmd](unpack(kwargs or {}))
  end)
  if not status_ok then
    Log:warn(cmd .. " failed with: " .. vim.inspect(msg))
    Log:trace(vim.inspect(vim.fn.eval "v:errmsg"))
  end
end

function plugin_loader.cache_clear()
  if vim.fn.delete(compile_path) == 0 then
    Log:debug "deleted packer_compiled.lua"
  end
end

function plugin_loader.recompile()
  plugin_loader.cache_clear()
  pcall_packer_command "compile"
  if utils.is_file(compile_path) then
    Log:debug "generated packer_compiled.lua"
  end
end

function plugin_loader.reload(configurations)
  _G.packer_plugins = _G.packer_plugins or {}
  for k, v in pairs(_G.packer_plugins) do
    if k ~= "packer.nvim" then
      _G.packer_plugins[v] = nil
    end
  end
  plugin_loader.load(configurations)

  plugin_loader.ensure_plugins()
end

function plugin_loader.load(configurations)
  Log:debug "loading plugins configuration"
  local packer_available, packer = pcall(require, "packer")
  if not packer_available then
    Log:warn "skipping loading plugins until Packer is installed"
    return
  end
  local status_ok, _ = xpcall(function()
    packer.reset()
    packer.startup(function(use)
      for _, plugins in ipairs(configurations) do
        for _, plugin in ipairs(plugins) do
          use(plugin)
        end
      end
    end)
    -- colorscheme must get called after plugins are loaded or it will break new installs.
    vim.g.colors_name = lvim.colorscheme
    vim.cmd("colorscheme " .. lvim.colorscheme)
  end, debug.traceback)
  if not status_ok then
    Log:warn "problems detected while loading plugins' configurations"
    Log:trace(debug.traceback())
  end
end

function plugin_loader.get_core_plugins()
  local list = {}
  local plugins = require "lvim.plugins"
  for _, item in pairs(plugins) do
    if not item.disable then
      table.insert(list, item[1]:match "/(%S*)")
    end
  end
  return list
end

function plugin_loader.load_snapshot(snapshot_file)
  snapshot_file = snapshot_file or default_snapshot
  if not in_headless then
    vim.notify("Syncing core plugins is in progress..", vim.log.levels.INFO, { title = "lvim" })
  end
  Log:debug(string.format("Using snapshot file [%s]", snapshot_file))
  local core_plugins = plugin_loader.get_core_plugins()
  require("packer").rollback(snapshot_file, unpack(core_plugins))
end

function plugin_loader.sync_core_plugins()
  -- problem: rollback() will get stuck if a plugin directory doesn't exist
  -- solution: call sync() beforehand
  -- see https://github.com/wbthomason/packer.nvim/issues/862
  vim.api.nvim_create_autocmd("User", {
    pattern = "PackerComplete",
    once = true,
    callback = function()
      require("lvim.plugin-loader").load_snapshot(default_snapshot)
    end,
  })
  pcall_packer_command "sync"
end

function plugin_loader.ensure_plugins()
  vim.api.nvim_create_autocmd("User", {
    pattern = "PackerComplete",
    once = true,
    callback = function()
      Log:debug "calling packer.clean()"
      pcall_packer_command "clean"
    end,
  })
  Log:debug "calling packer.install()"
  pcall_packer_command "install"
end

return plugin_loader