local Statements = {}

function Statements:_add(name, stmtarr)
  if self.values[name] then
    return "Statement '", name, "' already exists."
  end
  local stmt = table.concat(stmtarr, "\n")
  self.values[name] = stmt
end

function Statements:_assert(lineN, ...)
  if ... then
    error("Error parsing "..self.curFile..". Line #"..lineN.. ". "..
      table.concat({...}, ""))
  else return lineN, ... end
end

function Statements:_addFile(file)
  self.curFile = file
  local name, stmtarr = nil, {}
  local first = true
  local lineN = 0

  for line in io.lines(file) do
    lineN = lineN + 1
    if first and line:match("^%s*$") then goto continue end
    local commentName = line:match("^--!%s*(.+)$")
    if commentName then
      if first then first = false
      else self:_assert(lineN, self:_add(name, stmtarr)) end
      name, stmtarr = commentName, {}
    else
      if first then self:_assert(lineN, "Meets unnamed SQL statement") end
      table.insert(stmtarr, line)
    end
    ::continue::
  end

  self:_assert(lineN, self:_add(name, stmtarr))
end

function Statements:new(...)
  local o = { values = {} }
  setmetatable(o, self)
  self.__index = self
  if ... then o:addFiles(...) end
  return o
end

function Statements:addFiles(...)
  local files = {...}
  if #files == 0 then error('No files to load') end
  for _,f in ipairs(files) do self:_addFile(f) end
end

return Statements