local cache = (package.loaded["fs.rtfs"] or {}).cache or {hitsR=0, hitsW=0, missesR=0, missesW=0}
local proxy = {}
local rtfs = {proxy=proxy, cache=cache}
local sbformat = ">c4I2I8c18" -- "rtfs" magic, version, index size in entries, label. label length subject to change.

rtfs.cacheSize = computer.totalMemory() // 1024 // 16

-- data mangling functions
function rtfs.fnormalize(s)
 return table.concat(fs.segments(s),"/")
end
function proxy:log(message,level)
 syslog(message,level or syslog.debug,"rtfs:"..self.label)
end


-- just for ease-of-use
function rtfs.getProxy(addr)
 if type(addr) == "string" then
  return component.proxy(component.get(addr,"partition") or component.get(addr) or addr)
 end
 return addr
end

-- cache stuff
local function cacheClean()
 while #cache > rtfs.cacheSize do
  table.remove(cache, 1)
 end
end
function proxy:cachedRead(s)
 for k,v in ipairs(cache) do
  if v[1] == self.d.address and v[2] == s then
   rtfs.cache.hitsR = rtfs.cache.hitsR + 1
   return v[3]
  end
 end
 cache[#cache + 1] = {self.d.address, s, self.d.readSector(s)}
 rtfs.cache.missesR = rtfs.cache.missesR + 1
 cacheClean()
 return cache[#cache][3]
end
function proxy:cachedWrite(s,d)
 for k,v in ipairs(cache) do
  if v[1] == self.d.address and v[2] == s then
   table.remove(cache, k)
  end
 end
 cache[#cache + 1] = {self.d.address, s, d}
 cacheClean()
 return self.d.writeSector(s,d)
end

function rtfs.mount(a)
 local d = rtfs.getProxy(a)
 local magic, version = string.unpack(sbformat, d.readSector(1))
 assert(magic == "rtfs","not an rtfs filesystem")
 local w, l = pcall(require, string.format("fs.rtfs.v%i", version))
 if w then return l.mount(a) end
 error("incompatible rtfs version")
end
function rtfs.format(a,l)
 return require("fs.rtfs.v1").format(a,l)
end

return rtfs