local ramfs = { }

function ramfs.mount(dir, nodeType)
  if nodeType == 'directory' then
    return {
      nodes = { },
      size = 0,
    }
  elseif nodeType == 'file' then
    return {
      size = 0,
    }
  end
  error('ramfs syntax: [directory, file]')
end

function ramfs.delete(node, dir)
  if node.mountPoint == dir then
    fs.unmount(node.mountPoint)
  end
end

function ramfs.exists(node, fn)
  return node.mountPoint == fn
end

function ramfs.getSize(node)
  return node.size
end

function ramfs.isReadOnly()
  return false
end

function ramfs.makeDir(node, dir)
  fs.mount(dir, 'ramfs', 'directory')
end

function ramfs.isDir(node)
  return not not node.nodes
end

function ramfs.getDrive()
  return 'ram'
end

function ramfs.list(node, dir, full)
  if node.nodes and node.mountPoint == dir then
    local files = { }
    if full then
      for f,n in pairs(node.nodes) do
        table.insert(files, {
          name = f,
          isDir = fs.isDir(fs.combine(dir, f)),
          size = fs.getSize(fs.combine(dir, f)),
        })
      end
    else
      for k,v in pairs(node.nodes) do
        table.insert(files, k)
      end
    end
    return files
  end
  error('Not a directory')
end

function ramfs.open(node, fn, fl)

  if fl ~= 'r' and fl ~= 'w' and fl ~= 'rb' and fl ~= 'wb' then
    error('Unsupported mode')
  end

  if fl == 'r' then
    if node.mountPoint ~= fn then
      return
    end

    local ctr = 0
    local lines
    return {
      readLine = function()
        if not lines then
          lines = Util.split(node.contents)
        end
        ctr = ctr + 1
        return lines[ctr]
      end,
      readAll = function()
        return node.contents
      end,
      close = function()
        lines = nil
      end,
    }
  elseif fl == 'w' then
    node = fs.mount(fn, 'ramfs', 'file')

    local c = ''
    return {
      write = function(str)
        c = c .. str
      end,
      writeLine = function(str)
        c = c .. str .. '\n'
      end,
      flush = function()
        node.contents = c
        node.size = #c
      end,
      close = function()
        node.contents = c
        node.size = #c
        c = nil
      end,
    }
  elseif fl == 'rb' then
    if node.mountPoint ~= fn or not node.contents then
      return
    end

    local ctr = 0
    return {
      read = function()
        ctr = ctr + 1
        return node.contents[ctr]
      end,
      close = function()
      end,
    }

  elseif fl == 'wb' then
    node = fs.mount(fn, 'ramfs', 'file')

    local c = { }
    return {
      write = function(b)
        table.insert(c, b)
      end,
      flush = function()
        node.contents = c
        node.size = #c
      end,
      close = function()
        node.contents = c
        node.size = #c
        c = nil
      end,
    }
  end
end

return ramfs