strings.lua

local M = {}

local alnum = "abcdefghijklmnopqrstuvwxyz"
  .. "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
  .. "1234567890"

---@param len integer string length
---@param charset? string character set to use
---@return string random generated string
function M.random(len, charset)
  charset = charset or alnum
  len = len or 16

  local result = ""
  ---@diagnostic disable-next-line: unused-local
  for i = 1, len do
    local ch_idx = math.random(1, #charset)
    result = result .. charset:sub(ch_idx, ch_idx)
  end
  return result
end

function M.strip(s)
  return s:gsub("^[%s]+", ""):gsub("[%s]+$", "")
end

---@param n integer number to convert
---@param charset? string character set to use
---@return string string converted string
function M.itoa(n, charset)
  charset = charset or alnum
  assert(n >= 0, "expected zero or greater")
  assert(math.floor(n) == n, "expected integer")
  if n == 0 then
    return charset:sub(1, 1)
  end

  local s = ""
  while n > 0 do
    local idx = n % #charset
    s = charset:sub(idx, idx) .. s
    n = math.floor(n / #charset)
  end

  return s
end

---@param s string string to split by newline
---@param strip? boolean true to remove surrounding whitespace
---@param blank? boolean false to disallow whitespace-only lines
---@return string[] lines array of lines
function M.lines(s, strip, blank)
  strip = strip or false
  blank = blank ~= false
  local lines = {}

  while s and #s > 0 do
    local eol, _ = s:find("\n", 1, true)
    local line = eol and s:sub(1, eol) or s
    s = eol and s:sub(eol + 1) or ""

    line = line:gsub("\r$", "")
    if strip then
      line = line:gsub("^%s+", ""):gsub("%s+$", "")
    end

    if blank or not line:match("^%s*$") then
      table.insert(lines, line)
    end
  end

  return lines
end

return M