local M = {}
local e = vim.fn.fnameescape
local fp_sep = vim.loop.os_uname().sysname:lower():match('windows') and '\\' or '/' -- \ for windows, mac and linux both use \


---Print an error message
--@param msg string
--@param error string
--@return string
local function echoerr(msg, error)
  vim.api.nvim_echo({
    { "[persisted.nvim]: ", "ErrorMsg" },
    { msg, "WarningMsg" },
    { error, "Normal" },
  }, true, {})
end

--- Escape special pattern matching characters in a string
---@param input string
---@return string
local function escape_pattern(input)
  local magic_chars = { "%", "(", ")", ".", "+", "-", "*", "?", "[", "^", "$" }

  for _, char in ipairs(magic_chars) do
    input = input:gsub("%" .. char, "%%" .. char)
  end

  return input
end

--- Get the last element in a table
---@param table table
---@return string
function M.get_last_item(table)
  local last
  for _, _ in pairs(table) do
    last = #table - 0
  end
  return table[last]
end

---Check if a target directory exists in a given table
---@param dir string
---@param dirs_table table
---@return boolean
function M.dirs_match(dir, dirs_table)
  dir = vim.fn.expand(dir)
  return dirs_table
    and next(vim.tbl_filter(
      function(pattern)
        if pattern.exact then
          -- The pattern is actually a table
          pattern = pattern[1]
          -- Stripping off the trailing backslash that a user might put here,
          -- but only if we aren't looking at the root directory
          if pattern:sub(-1) == fp_sep and pattern:len() > 1 then
            pattern = pattern:sub(1, -2)
          end
          return dir == pattern
        else
          return dir:find(escape_pattern(vim.fn.expand(pattern)))
        end
      end,
    dirs_table))
end

---Get the directory pattern based on OS
---@return string
function M.get_dir_pattern()
  local pattern = "/"
  if vim.fn.has("win32") == 1 then
    pattern = "[\\:]"
  end
  return pattern
end

---Load the given session
---@param session string
---@param silent boolean Load the session silently?
---@return nil|string
function M.load_session(session, silent)
  vim.api.nvim_exec_autocmds("User", { pattern = "PersistedLoadPre", data = session })

  local ok, result = pcall(vim.cmd, (silent and "silent " or "") .. "source " .. e(session))
  if not ok then
    return echoerr("Error loading the session! ", result)
  end

  vim.g.persisted_exists = true
  vim.g.persisted_loaded_session = session
  vim.api.nvim_exec_autocmds("User", { pattern = "PersistedLoadPost", data = session })
end

return M