local net = require "net"
local md = require "mdparse"
local event = require "event"
local fs = require "filesystem"
local computer = require "computer"
local home = "file:///usr/doc/mdbrowse.md"
local url = home
local cline = 1
local lines, links, listeners, history = {}, {}, {}, {}
local width, height = 80, 23
local run = true

local function pushhistory(url)
 history[#history+1] = url
end
local function pophistory()
 local rurl = history[#history] or home
 history[#history] = nil
 return rurl
end

local function parseurl(url)
 local proto,addr = url:match("(.-)://(.+)")
 addr = addr or url
 local hp, path = addr:match("(.-)(/.*)")
 hp, path = hp or addr, path or "/"
 local host, port = hp:match("(.+):(.+)")
 host = host or hp
 path = fs.canonical(path)
 return proto, host, port, path
end

function addButton(x,y,l,a)
 local len = l:len() + 2
 local function hf(_,_,tx,ty)
  if y == ty and tx >= x and tx <= x+len then
   io.write("\a")
   computer.pushSignal("mdbrowsebutton",a)
  end
 end
 event.listen("touch",hf)
 listeners[#listeners+1] = hf
end
function dropButtons()
 for k,v in pairs(listeners) do
  event.ignore("touch",v)
 end
end

function loadpage()
 local protocol, host, port, path = parseurl(url)
 protocol = protocol or "file"
 if protocol == "file" then
  local f = io.open(host..path,"rb")
  if not f then
   url = pophistory()
   return false, "not found"
  end
  lines, links = md.reflow(f:read("*a"),width)
  f:close()
  return true
 elseif protocol == "fget" then
  port = tonumber(port) or 70
  local socket = net.open(host,port)
  if socket then
   io.write("\27[u\27[2KConnection established.")
   local buf = ""
   socket:write("t"..path.."\n")
   local c = socket:read(1)
   repeat
    c = socket:read(1)
    os.sleep(0.5)
   until c ~= ""
   if c == "n" then 
    buf = path..": Not found.\n"
   elseif c == "f" then 
    buf = "Failure: \n"
   elseif c == "d" then
    buf = "# Directory listing for "..path.."\n"
   end
   repeat
    l = socket:read(1024)
    buf = buf .. l
    io.write("\27[u\27[2KRead "..tonumber(buf:len()).." bytes")
    os.sleep(0.5)
   until socket.state == "closed" and l == ""
   if c == "d" then
    local first, nbuf = false, ""
    for line in buf:gmatch("[^\n]+") do
     if first then
      line = "- ["..line.."]("..line..")"
     end
     nbuf = nbuf .. line .. "\n"
     first = true
    end
    buf = nbuf
   end
   lines, links = md.reflow(buf,width)
   return true
  else
   url = pophistory()
   return false, "unable to load"
  end
 end
end

function drawpage()
 dropButtons()
 if cline < 1 then
  cline = 1
 elseif cline > #lines then
  cline = #lines
 end
 io.write("\27[2J\27[H")
 for i = cline, cline+height do
  print((lines[i] or ""):sub(1,width))
 end
 for k,v in pairs(links) do
  if v[1] >= cline and v[1] <= height+cline then
   addButton(v[2],(v[1])-cline+1,v[3],v[4])
  end
 end
 local lstring = tostring(cline).."-"..tostring(cline+height).."/"..tostring(#lines)
 io.write("\27[s"..lstring.." "..url)
end

function gourl(nurl)
 pushhistory(url)
 -- check for a protocol:// part
 if nurl:match(".+://") then
  url = nurl
 -- check for a / -- root relative
 elseif nurl:sub(1,1) == "/" then
  url = (url:match(".+://.-/" or url:match(".+://.+/?").."/")) .. nurl
 -- fail and assume relative
 else
  local host = (url:match(".+://.-/") or url:match(".+://.+/?").."/")
  local path = url:sub(host:len()+1)
  local tPath = fs.segments(path)
  local ntPath = fs.segments(nurl)
  if path:sub(path:len(),path:len()) ~= "/" then
   tPath[#tPath] = nil
  end
  for k,v in ipairs(ntPath) do
   tPath[#tPath+1] = v
  end
  url = host:sub(1,-2)
  for k,v in ipairs(tPath) do
   url = url .. "/" .. v
  end
  if nurl:sub(nurl:len(),nurl:len()) == "/" then
   url = url .. "/"
  end
 end
end

loadpage()
drawpage()
while run do
 local tev = {event.pull()}
 if tev[1] == "key_down" then
  if tev[3] == 0 and tev[4] == 200 then -- up
   cline = cline - 1
   drawpage()
  elseif tev[3] == 0 and tev[4] == 208 then -- down
   cline = cline + 1
   drawpage()
  elseif tev[3] == 0 and tev[4] == 203 then -- left
   url = pophistory()
   cline = 1
   loadpage()
   drawpage()
  elseif tev[3] == 0 and tev[4] == 209 then -- page down
   cline = cline + height
   drawpage()
  elseif tev[3] == 0 and tev[4] == 201 then -- page up
   cline = cline - height
   drawpage()
  elseif tev[3] == 113 and tev[4] == 16 then -- q
   run = false
  elseif tev[3] == 111 then -- o
   io.write("\27[u\27[2K\27[sURL: ")
   gourl(io.read())
   cline = 1
   loadpage()
   drawpage()
  end
 elseif tev[1] == "mdbrowsebutton" then
  gourl(tev[2])
  cline = 1
  loadpage()
  drawpage()
 end
end
dropButtons()
io.write("\27[2J\27[H")