local _,serial = pcall(require,"serialization")
local doc = {}
doc.searchers = {}
doc.tctab = {
 ["string"] = 31,
 ["table"] = 32,
 ["number"] = 33,
 ["boolean"] = 35,
 ["function"] = 36
}

function doc.parsefile(path) -- string -- table -- parses file from *path* to return a documentation table
 local fdoc = {}
 local f = io.open(path)
 local lines = {}
 for l in f:read("*a"):gmatch("[^\n]+") do
  if l:find("function") and not l:find("local") then
   lines[#lines+1] = l
  end
 end
 for k,v in pairs(lines) do
  local name, args, desc = v:match("function%s+(.+)%s*%((.*)%)%s*%-%-%s*(.+)")
  if name and args and desc then
   local fd = {["description"]=desc or desc,["args"]={},["atypes"]={}}
   for word in args:gmatch("[^%s,]+") do
    fd.args[#fd.args+1] = {word}
    fd.atypes[word] = "unknown"
   end
   local argtypes, outtypes, description = desc:match("(.-)%-%-(.-)%-%-%s*(.+)")
   if argtypes and outtypes and description then
    local wc = 1
    for word in argtypes:gmatch("%S+") do
     fd.args[wc][2] = word
     fd.atypes[fd.args[wc][1]] = word
     wc = wc + 1
    end
    local wc = 1
    for word in outtypes:gmatch("%S+") do
     fd.outtypes = fd.outtypes or {}
     fd.outtypes[#fd.outtypes+1] = word
    end
    fd.description = description
   end
   fdoc[name] = fd
  end
 end
 return fdoc
end

function doc.format(fdoc) -- table -- string -- returns VT100 formatted documentation from documentation table *fdoc*
 local rs = "" -- string to return
 for fname,finfo in pairs(fdoc) do
  if rs:len() > 0 then rs = rs .. "\n\n" end
  local as = "" -- string containing arguments for a given function, with colours for type
  for k,v in ipairs(finfo.args) do
   local c = doc.tctab[v[2]] or 0
   if k > 1 then
    as = as .. ", "
   end
   if v[2] then
    as = string.format("%s%s: \27[%im%s\27[0m",as,v[2],c,v[1])
   else
    as = string.format("%s\27[%im%s\27[0m",as,c,v[1])
   end
  end
  local rv = ""
  if finfo.outtypes then
   rv = ": "
   for k,v in ipairs(finfo.outtypes) do
    if k > 1 then
     rv = rv .. ", "
    end
    local c = doc.tctab[v] or 0
    rv = string.format("%s\27[%im%s\27[0m",rv,c,v)
   end
  end
  local nd = finfo.description
  for k,v in pairs(finfo.atypes) do
   local c = doc.tctab[v] or 7
   nd=nd:gsub("%*"..k.."%*","\27["..tostring(c).."m"..k.."\27[0m")
  end
  rs = string.format("%s\27[36m%s\27[0m(%s)%s\n%s",rs,fname,as,rv,nd)
 end
 return rs
end

function doc.searchers.lib(name) -- string -- string string -- Tries to find a documentation from a library with *name*. Returns either a string of documentation, or false and a reason.
 local lib = os.getenv("LIB") or "/boot/lib"
 local dt
 for d in lib:gmatch("[^\n]+") do
  if fs.exists(d.."/"..name) then
   dt = doc.parsefile(d.."/"..name)
  elseif fs.exists(d.."/"..name..".lua") then
   dt = doc.parsefile(d.."/"..name..".lua")
  end
 end
 if not dt then return false, "unable to find documentation for "..tostring(name) end
 return doc.format(dt)
end
function doc.searchers.cdoc(topic) -- string -- string string -- Searches for documentation labelled as *topic* in .dict files under /boot/doc/
 if not serial then return end
 for k,v in ipairs(fs.list("/boot/doc")) do
  if v:sub(-5) == ".dict" then
   local f=io.open("/boot/doc/"..v,"rb")
   for line in f:lines() do
    local mname, docs = line:match("^(.-)\t(.+)$")
    if mname == topic or mname == topic..".lua" then
     return doc.format(serial.unserialize(docs))
    end
   end
  end
 end
end

function doc.docs(topic) -- string -- boolean -- Displays the documentation for *topic*, returning true, or errors. Also callable as just doc().
 local lib = os.getenv("LIB") or "/boot/lib"
 local dt
 for k,v in pairs(doc.searchers) do
  dt=v(topic)
  if dt then
   print(dt)
   return true
  end
 end
 error("unable to find documentation for "..tostring(name))
end

return setmetatable(doc,{__call=function(_,topic) return doc.docs(topic) end})