"guihelp" - GUI Help Viewer - v0.1

local startupPage, mode = ...

if not term.isColor() then
  print("WARNING: This program has been designed to run on Advanced Computer")
  print("It should run fine, but you won't be able to follow links or click buttons")
  print("To access button functions, use the following keys:")
  print("Quit - Q, Home - 0 or H, Reload - 5, F5 or R, Back - 4 or Backspace, Next - 6")
  print("Press any key to continue")
  os.pullEvent("key")
end

local title = "ERROR"
local text = "ERROR: NO PAGE LOADED"
local pos = 1
local textLength = 1
local lowercase = false

local offlineMode = false
if not http then offlineMode = true end
if mode then
  if mode == "online" then
    if offlineMode then
      error("HTTP API not available", 0)
    end
    offlineMode = false
  elseif mode == "offline" then
    offlineMode = true
  else
    error("Unkown mode, use \"offline\" or \"online\"", 0)
  end
end

function error404()
  title = "404 ERROR"
  text = "\\v;Not Found!\\r;"
end

function loadOfflinePage(page)
  title = page

  if page == "index" then
    text = "Help topics available:\n"
    for i, topic in pairs(help.topics()) do
      text = text .. "\\l"..topic..";"..topic.."\\r;\n"
    end
  else
    local filename = help.lookup(page)
    if filename == nil then
      return error404()
    end

    local file = fs.open(filename, "r")
    text = file.readAll()
    file.close()
  end

  if page == "apis" then
    -- This is code fragment from "apis" program
    local tApis = {}
    for k,v in pairs( _G ) do
      if type(k) == "string" and type(v) == "table" and k ~= "_G" then
        table.insert( tApis, k )
      end
    end
    table.insert( tApis, "shell" )
    table.sort( tApis )

    text = text .. "\n\nList of available APIs:\n"
    for k,v in pairs(tApis) do
      local tag = "\\x"
      if help.lookup(v) then
        tag = "\\l"..v..";"
      end
      text = text .. tag .. v .. "\\r;\n"
    end
  end

  if page == "programs" then
    local programs = shell.programs()
    text = text .. "\n\nList of available programs:\n"
    for k,v in pairs(programs) do
      local tag = "\\x;"
      if help.lookup(v) then
        tag = "\\l"..v..";"
      end
      text = text .. tag .. v .. "\\r;\n"
    end
  end

  function detect_links(s)
    if s:sub(1,5) == "help " then
      local target = s:sub(6)
      if target == "<program>" then target = "programs" end
      if target == "index" or help.lookup(target) ~= nil then
        return "\"\\l"..target..";"..s.."\\r;\""
      end
    elseif s == "programs" or s == "apis" then
      return "\"\\l"..s..";"..s.."\\r;\""
    end
    return "\"\\x;"..s.."\\r;\""
  end

  text = string.gsub(text, "\"(.-)\"", detect_links)
  text = string.gsub(text, "https?://[a-zA-Z0-9./-]*", "\\u;%1\\r;")
  text = string.gsub(text, "Ctrl%+(.)", "\\v;Ctrl+%1\\r;")
end

function loadOnlinePage(page)
  if page == "Main Page" or page == "Main_Page" then
    -- There is just too much HTML in there
    title = "Main Page"
    text = "   \\h; Welcome to the ComputerCraft Wiki! \\r;\n\n"
    test = text.."\\s;Wiki Contents\\r;\n"
    text = text.."\\lTutorials;Tutorial List\\r;\n"
    text = text.."\\lCategory:Programs;Program List\\r;\n"
    text = text.."\\lCategory:APIs;API List\\r;\n"
    --text = text.."\\lRecipes;Recipe List\\r;\n" --TODO: We'll handle images somehow
    text = text.."\\lCategory:Peripherals;Peripherals & Addons\\r;\n"
    text = text.."\\lCategory:Notable Programs;Notable Programs\\r;\n"
    text = text.."\\lCategory:OSes;Operating Systems\\r;\n"
    text = text.."\\lChangelog;ComuterCraft Changelog\\r;\n"
    --text = text.."\\lWiki Todo;Wiki Todo\\r;\n" -- I don't think we need that
    return
  end

  local h = http.get("http://computercraft.info/wiki/api.php?format=xml&action=query&prop=revisions&titles="..textutils.urlEncode(page).."&rvprop=content", {["User-Agent"] = "GUI Help Viewer by krzys_h"})
  if not h then
    title = "ERROR"
    text = "\\v;CONNECTION ERROR!\\r;\nMake sure you have internet connection and computercraft.info website is working"
    return
  end
  if h.getResponseCode() ~= 200 then
    title = h.getResponseCode().." ERROR"
    text = "\\v;SERVER RETURNED ERROR "..h.getResponseCode().."\\r;"
    h.close()
    return
  end

  local data = h.readAll()
  h.close()

  title = string.match(data, "title=\"(.-)\"")
  if title == nil then
    title = page
  end

  text = string.match(data, "<rev xml:space=\"preserve\">(.-)</rev>")
  if text == nil then
    return error404()
  end

  if text:sub(1, 10) == "#REDIRECT " then
    loadOnlinePage(text:sub(13, -3))
    return
  end

  text = string.gsub(text, "&lt;", "<")
  text = string.gsub(text, "&gt;", ">")
  text = string.gsub(text, "&quot;", "\"")
  text = string.gsub(text, "<!--(.-)-->", "")

  -- Computer terminal doesn't like special chars
  text = string.gsub(text, "’", "'")
  text = string.gsub(text, "—", "-")

  text = string.gsub(text, "<table.*>", "")
  text = string.gsub(text, "</table>", "")
  text = string.gsub(text, "<tr.->", "")
  text = string.gsub(text, "</tr>", "")
  text = string.gsub(text, "<td.->", "")
  text = string.gsub(text, "</td>", "")

  text = string.gsub(text, "__TOC__", "") --TODO: We could implement TOC...
  text = string.gsub(text, "__NOTOC__", "")

  function lowercase_match(s)
    lowercase = true
    return ""
  end
  text = string.gsub(text, "{{lowercase}}", lowercase_match)
  text = string.gsub(text, "{{Lowercase}}", lowercase_match)

  text = string.gsub(text, "'''(.-)'''", "%1")
  text = string.gsub(text, "''(.-)''", "%1")
  text = string.gsub(text, "'(.-)'", "%1")

  text = string.gsub(text, "{{type|(.-)}}", "\\t;%1\\r;")
  text = string.gsub(text, "{{Type|(.-)}}", "\\t;%1\\r;")
  text = string.gsub(text, "<var>(.-)</var>", "\\v;%1\\r;")
  text = string.gsub(text, "<code>(.-)</code>", "\\x;%1\\r;") --TODO: syntax highlighting?
  text = string.gsub(text, "<nowiki/>", "")
  text = string.gsub(text, "<em>(.-)</em>", "%1")
  text = string.gsub(text, "<br />", "\n")
  text = string.gsub(text, "<br/>", "\n")
  text = string.gsub(text, "<pre>(.-)</pre>", "\\x;%1\\r;")
  text = string.gsub(text, "<tt>(.-)</tt>", "\\x;%1\\r;")

  text = string.gsub(text, "<div(.+)>(.-)</div>", "%2")

  function link_replace(link)
    local linktarget = link
    local linkname = link
    local splitpos = link:find("|")
    if splitpos then
      linktarget = link:sub(1, splitpos-1)
      linkname = link:sub(splitpos+1)
    end
    if linktarget:sub(1, 1) == ":" then
      linktarget = linktarget:sub(2)
    end
    if linktarget:sub(1, 5) == "File:" then return "" end
    if linktarget:sub(1, 6) == "Image:" then return "" end
    return "\\l"..linktarget..";"..linkname.."\\r;"
  end

  text = string.gsub(text, "%[%[Category:(.-)%]%]", "") --TODO: category display?
  text = string.gsub(text, "%[%[(.-)%]%]", link_replace)
  text = string.gsub(text, "%[(.-) (.-)%]", "\\u;%2 (%1)\\r;")
  text = string.gsub(text, "%[(.-)%]", "\\u;%1\\r;")

  text = parseTemplates(text)

  text = string.gsub(text, "\n===(.-)===\n", "\n  \\s;%1\\r;\n")
  text = string.gsub(text, "\n==(.-)==\n", "\n   \\h;%1\\r;\n")
  text = string.gsub(text, "\n=(.-)=\n", "\n    \\c;%1\\r;\n")

  if title:sub(1, 9) == "Category:" then
    local h = http.get("http://computercraft.info/wiki/api.php?format=xml&action=query&list=categorymembers&cmtitle="..textutils.urlEncode(page).."&cmlimit=500", {["User-Agent"] = "GUI Help Viewer by krzys_h"})
    if not h then
      title = "ERROR"
      text = "\\v;CONNECTION ERROR!\\r;\nMake sure you have internet connection and computercraft.info website is working"
      return
    end
    if h.getResponseCode() ~= 200 then
      title = h.getResponseCode().." ERROR"
      text = "\\v;SERVER RETURNED ERROR "..h.getResponseCode().."\\r;"
      h.close()
      return
    end

    local data = h.readAll()
    h.close()

    text = text .. "\n  \\h; Pages in this category: \\r;\n"
    for page in string.gmatch(data, "title=\"(.-)\"") do
      text = text .. "\\l" .. page .. ";" .. page .. "\\r;\n"
    end
  end
end

function closest(...)
  local x = {...}
  local r
  for i, d in pairs(x) do
    if x[i] then
      if not r or x[i] < r then
        r = x[i]
      end
    end
  end
  return r
end

-- http://lua-users.org/wiki/StringTrim
function trim(s)
  return (s:gsub("^%s*(.-)%s*$", "%1"))
end

function findParam(params, name)
  for id, data in pairs(params) do
    local x = string.find(data, "=")
    if x ~= nil then
      thisname = trim(string.sub(data, 1, x-1))
      if thisname == name then
        return string.sub(data, x+1)
      end
    end
  end
  if type(name) == "number" then
    return params[name]
  end
  return nil
end

function expandTemplate(name, params)
  if name == "API table" then
    return " \\a;  "..findParam(params, 1).." (API)  \\r;\n"..string.sub(findParam(params, 3), 3)
  end
  if name == "API table/row" then
    return findParam(params, 1).." \\z;--\\r; "..findParam(params, 2).." \\z;--\\r; "..findParam(params, 3).."\n"
  end
  if name == "Deprecated" then
    return "\\x;These functions have been removed from ComputerCraft\\r;"
  end
  if name == "Stub" then
    return "\\x;This article is a stub\\r;\n"
  end
  if name == "ToDelete" then
    return "\\x;This page is marked for deletion!\\r;\n"
  end
  if name == "Example" then
    local s = " \\s;Example\\r;\n"..findParam(params, "desc").."\n\n\\x;"..findParam(params, "code").."\\r;\n"
    if findParam(params, "output") then
      s = s .. "\nOutput:\n\\x;"..findParam(params, "output").."\\r;\n"
    end
    return s
  end
  if name == "Event" then
    local s = " \\a;  Event "..findParam(params, "name").."  \\r;\n"
    s = s .. findParam(params, "desc") .. "\n"
    for i=1,5 do
      if findParam(params, "return"..tostring(i)) then
        s = s .. "\\x;Return "..tostring(i)..":\\r; " .. findParam(params, "return"..tostring(i)) .. "\n"
      end
    end
    if findParam(params, "examples") then
      s = s .. "\n" .. findParam(params, "examples")
    end
    return s
  end
  if name == "Function" then
    s = " \\a;  Function "..findParam(params, "name").."  \\r;\n"
    s = s .. findParam(params, "desc") .. "\n"
    if findParam(params, "args") then
      s = s .. "\\x;Syntax:\\r; "..findParam(params, "name").."("..findParam(params, "args")..")\n"
    else
      s = s .. "\\x;Syntax:\\r; "..findParam(params, "name").."()\n"
    end
    if findParam(params, "returns") then
      s = s .. "\\x;Returns:\\r; "..findParam(params, "returns").."\n"
    else
      s = s .. "\\x;Returns:\\r; \\t;nil\\r;\n"
    end
    if findParam(params, "examples") then
      s = s .. "\n" .. findParam(params, "examples")
    end
    return s
  end
  return "\\v;UNKNOWN TEMPLATE: "..name.."\\r;"
end

function parseTemplate(s, p)
  local res = s
  local params = {}
  while true do
    nextparam = string.find(res, "|", p)
    subtemplate = string.find(res, "{{", p)
    templateend = string.find(res, "}}", p)
    local x = closest(nextparam, subtemplate, templateend)
    if x == nil then
      error("Unclosed template")
    elseif x == templateend or x == nextparam then
      param = trim(string.sub(res, p, x-1))
      table.insert(params, param)
      p = x+1
      if x == templateend then
        p = p + 1
        break
      end
    elseif x == subtemplate then
      pos_start = x-2
      _, tpl, pos_end = parseTemplate(res, x+2)
      res = string.sub(
      res, 1, pos_start) .. tpl .. string.sub(res, pos_end+1)
    end
  end
  local name = params[1]
  table.remove(params, 1)
  return res, expandTemplate(name, params), p
end

function parseTemplates(s)
  local p = 1
  local out = ""
  while p <= #s do
    templatepos = string.find(s, "{{", p)
    if templatepos == nil then
      out = out .. string.sub(s, p)
      break
    else
      out = out .. string.sub(s, p, templatepos-1)
      p = templatepos+2
      s, res, p = parseTemplate(s, p)
      out = out .. res
    end
  end
  return out
end

local hist = {}
local hist_pos = 0
function loadPage(page, new_page)
  if new_page == nil then new_page = true end
  lowercase = false
  if not offlineMode then
    title = "<LOADING>"
    text = "  \\t;Loading, please wait...\\r;"
    pos = 1
    generateWindows()
    draw()

    loadOnlinePage(page)
  else
    loadOfflinePage(page)
  end
  if new_page then
    while hist_pos < #hist do
      table.remove(hist)
    end
    table.insert(hist, page)
    hist_pos = #hist
  end
  pos = 1
  if lowercase then
    title = title:sub(1,1):lower()..title:sub(2)
  end
end

function history(amount)
  local old_hist = hist_pos
  hist_pos = hist_pos + amount
  if hist_pos >= #hist then
    hist_pos = #hist
  end
  if hist_pos <= 1 then
    hist_pos = 1
  end
  if hist_pos ~= old_hist then
    loadPage(hist[hist_pos], false)
    generateWindows()
  end
end

function reload()
  loadPage(hist[hist_pos], false)
  generateWindows()
end

local w, h = term.getSize()
local header = window.create(term.current(), 1, 1, w, 2)
local content = window.create(term.current(), 1, 3, w, 1000)
local links = {}
function generateWindows()
  w, h = term.getSize()

  -- draw content
  local old = term.current()
  term.redirect(content)
  term.clear()
  term.setCursorPos(1, 1)
  local p = 1
  local linktarget, linkstartx, linkstarty, linkendx, linkendy
  local inCode = false
  links = {}
  while p <= #text do
    controlpos, controlend = string.find(text, "\\.-;", p)
    if controlpos == nil then
      write(string.sub(text, p))
      break
    else
      write(string.sub(text, p, controlpos-1))
      p = controlend + 1
      c = string.sub(text, controlpos+1, controlpos+1)
      if c == "l" and term.isColor() then -- l = link
        linktarget = string.sub(text, controlpos+2, controlend-1)
        linkstartx, linkstarty = term.getCursorPos()
        term.setTextColor(colors.lightBlue)
      end
      if c == "r" then -- r = reset formatting
        if linktarget then
          linkendx, linkendy = term.getCursorPos()
          table.insert(links, {startx = linkstartx, starty = linkstarty, endx = linkendx, endy = linkendy, target = linktarget})
          linktarget = nil
        end
        inCode = false
        term.setBackgroundColor(colors.black)
        term.setTextColor(colors.white)
      end
      if c == "t" and term.isColor() then -- t = type
        term.setTextColor(colors.lime)
      end
      if c == "c" and not inCode and term.isColor() then -- c = chapter header
        --TODO: I don't really like that color...
        term.setBackgroundColor(colors.yellow)
        term.setTextColor(colors.black)
      end
      if c == "h" and not inCode and term.isColor() then -- h = header
        term.setBackgroundColor(colors.blue)
      end
      if c == "s" and not inCode and term.isColor() then -- s = subheader
        term.setBackgroundColor(colors.purple)
      end
      if c == "a" and not inCode and term.isColor() then -- a = api header
        term.setBackgroundColor(colors.green)
      end
      if c == "z" and term.isColor() then -- z = table separator
        term.setTextColor(colors.gray)
      end
      if c == "v" and term.isColor() then -- v = var
        term.setTextColor(colors.red)
      end
      if c == "x" and term.isColor() then -- x = code / comment
        term.setTextColor(colors.lightGray)
        inCode = true
      end
      if c == "u" and term.isColor() then -- u = unclickable link (e.g. http)
        term.setTextColor(colors.blue)
      end
    end
  end
  _, textLength = term.getCursorPos()
  term.redirect(old)

  -- draw header
  local old = term.current()
  term.redirect(header)
  term.setBackgroundColor(colors.black)
  term.setTextColor(colors.white)
  term.clear()
  term.setCursorPos(1, 1)
  if not term.isColor() then
    term.setBackgroundColor(colors.white)
    term.setTextColor(colors.black)
  else
    term.setBackgroundColor(colors.lightGray)
    term.setTextColor(colors.red)
  end
  write("[X] ")
  if term.isColor() then
    term.setTextColor(colors.orange)
  end
  write("[H] ")
  if term.isColor() then
    term.setTextColor(colors.blue)
  end
  write("[<]")
  if term.isColor() then
    term.setTextColor(colors.lime)
  end
  write("[R]")
  if term.isColor() then
    term.setTextColor(colors.blue)
  end
  write("[>]")
  if term.isColor() then
    term.setTextColor(colors.black)
  end
  local t = "  "..title.." --- GUI Help Viewer"
  if #t < w-17-11 then t = t .. " by krzys_h" end
  for i=0,w-#t-17 do t = t.." " end
  t = t:sub(1, w-17)
  print(t)
  term.redirect(old)
end

function draw()
  term.setBackgroundColor(colors.black)
  term.setTextColor(colors.white)
  term.clear()
  term.setCursorPos(1, 1)

  content.reposition(1, 3-pos+1, w, 1000)
  header.reposition(1, 1, w, 2)
end

function move(x)
  pos = pos + x
  if pos > textLength-(h-3) then pos = textLength-(h-3) end
  if pos < 1 then pos = 1 end
end

function getLink(x, y)
  for id, link in pairs(links) do
    if (y > link.starty or (y == link.starty and x >= link.startx)) and (y < link.endy or (y == link.endy and x < link.endx)) then
      return link
    end
  end
  return nil
end

function handleClick(x, y, button)
  if y == 1 then
    if x >= 1 and x <= 3 then
      os.queueEvent("terminate")
    end
    if x >= 5 and x <= 7 then
      loadPage(offlineMode and "intro" or "Main Page")
      generateWindows()
    end
    if x >= 9 and x <= 11 then
      history(-1)
    end
    if x >= 12 and x <= 14 then
      reload()
    end
    if x >= 15 and x <= 17 then
      history(1)
    end
  end

  local y = y - 2 + pos - 1
  local link = getLink(x, y)
  if link then
    loadPage(link.target)
    generateWindows()
  end
end

function handleScroll(scroll)
  move(scroll)
end

function handleKey(key)
  if key == keys.down then
    move(1)
  end
  if key == keys.up then
    move(-1)
  end
  if key == keys.pageDown then -- TODO: doesn't work?
    move(h-2)
  end
  if key == keys.pageUp then -- TODO: doesn't work?
    move(-(h-2))
  end
  if key == keys.home then
    pos = 1
  end
  if key == keys["end"] then -- Lua doesn't like keys.end
    if textLength > (h-3) then
      pos = textLength-(h-3)
    else
      pos = 1
    end
  end
  if key == keys.q then
    os.queueEvent("terminate")
  end
  if key == keys.backspace or key == keys.four or key == keys.numPad4 then
    history(-1)
  end
  if key == keys.six or key == keys.numPad6 then
    history(1)
  end
  if key == keys.f5 or key == keys.five or key == keys.numPad5 or key == keys.r then
    reload()
  end
  if key == keys.zero or key == keys.numPad0 or key == keys.h then
    loadPage(offlineMode and "intro" or "Main Page")
    generateWindows()
  end
end

if not startupPage or startupPage == "-" then
  if offlineMode then
    startupPage = "intro"
  else
    startupPage = "Main Page"
  end
end
loadPage(startupPage)
generateWindows()
while true do
  draw()

  local event = {os.pullEventRaw()}
  if event[1] == "mouse_click" then
    handleClick(event[3], event[4], event[2])
  end
  if event[1] == "mouse_scroll" then
    handleScroll(event[2])
  end
  if event[1] == "key" then
    handleKey(event[2])
  end
  if event[1] == "term_resize" then
    generateWindows()
  end
  if event[1] == "terminate" then
    term.clear()
    term.setCursorPos(1, 1)
    break
  end
end