// ==UserScript==
// @name        4-ch.net Refresher
// @namespace   Violentmonkey Scripts
// @match       https://4-ch.net/*
// @version     1.0
// @author      -
// @description Shows how many new posts there are
// @grant GM_setValue
// @grant GM_getValue
// ==/UserScript==

//If there are some boards you aren't interested in, change fields in refresh_list1 from 1 to 0, you will not get updates from those

var boards_list = ["general", "hobby", "personal", "req", "tv", "japan", "games", "music", "book", "ascii", "dqn", "tech", "iaa", "language", "nihongo", "current"]
var board_is_shift_jis = [ 0,       0,          0,     0,    0,       0,       0,       0,      0,       1,     0,      0,     0,          0,         1,         0]
var refresh_list1 = [      1,       1,          1,     1,    1,       1,       1,       1,      1,       1,     1,      1,     1,          1,         1,         1]
//var refresh_list1 = [      1,       1,          0,     0,    0,       1,       1,       0,      0,       0,     0,      1,     0,         0,         0,         0]
//var refresh_list1 = [      0,       0,          0,     0,    0,       0,       0,       0,      0,       0,     1,      0,     0,         0,         0,         0]
//var refresh_list2 = [      0,       0,          1,     1,    1,       0,       0,       1,      1,       1,     1,      0,     1,         1,         1,         1]
var fetching = 0
var fetching_el = null
var board_new = new Array(boards_list.length)
var katalog_all = new Array(boards_list.length)
var katalog_all_old = new Array(boards_list.length)
var board_el_all = new Array(boards_list.length)

var refreshbox_peek

//data description:
//
//katalog elements are [thread_id, wasnt_deleted_yet, amount_of_replies, thread_title]
//
//katalog_new elements are element_type
//if element_type == 0, this is a "new thread" element, and the rest are [thread_id, amount_of_replies, thread_title]
//if element_type == 1, this is a "updated thread", and the rest are [index_in_katalog, new_amount_of_replies]
//if element_type == 2, this is a "deleted thread", and the rest are [index_in_katalog]

//TODO
// *) The results may be weird if you merged the data in the other tab, but still have the old data in memory on this one
// *) Maybe display new posts right in the tab, instead of making users go to that page.
// *) Add ability to hide some threads, and to get some threads more priority.
// *) And maybe keep track of last updated threads, I sometimes click merge too fast and regret doing it.

function start() {
  var stylebox = document.getElementById("stylebox")
  if (!stylebox) {
    return
  }
  stylebox.style.display="none"
  
  var l_board_new = GM_getValue("4c--board_new")
  if (l_board_new) board_new = JSON.parse(l_board_new)

  var titlebox = document.getElementById("stylebox")
  if (!titlebox) {
    error()
    return
  }

  var refreshboxouter = document.createElement("div")
  refreshboxouter.id = "refreshbox"
  refreshboxouter.classList.add("outerbox")
  titlebox.parentNode.insertBefore(refreshboxouter, titlebox)
  
  var refreshbox_base = document.createElement("div")
  refreshbox_base.id = "refreshbox_base"
  refreshbox_base.classList.add("innerbox")
  refreshboxouter.appendChild(refreshbox_base)
  
  var refreshbox = document.createElement("div")
  //refreshbox.innerHTML = "[styles:-]"
  //refreshbox.style.display = "flex"
  refreshbox_base.appendChild(refreshbox)
  
  refreshbox_peek = document.createElement("div")
  refreshbox_base.appendChild(refreshbox_peek)
  
  var style_show = document.createElement("a")
  style_show.href = "#"
  style_show.textContent = "[st-]"
  refreshbox.appendChild(style_show)
  style_show.onclick = function(evt) {
    //GM_setValue("/games/", "HAHA\nHAH")
    //alert("HI")
    if (stylebox.style.display == "") {
      stylebox.style.display = "none"
      style_show.textContent = "[st-]"
    } else {
      stylebox.style.display = ""
      style_show.textContent = "[st+]"
    }
    
    evt.stopPropagation();evt.preventDefault();return false;
  }
  
  var refresh = document.createElement("a")
  refresh.href = "#"
  refresh.textContent = "[refresh]"
  refreshbox.appendChild(refresh)
  refresh.onclick = function(evt) {
    var l_fetching = 0
    for (var board of boards_list) {
      l_fetching += refresh_list1[board]
    }
    fetching = l_fetching
    fetching_el.style.display=""
    //katalog_element_get(6) //"games"
    for (var board = 0; board < boards_list.length; board++) {
      if (refresh_list1[board]) {
        katalog_element_get(board)
      }
    }
    evt.stopPropagation();evt.preventDefault();return false;
  }
  
  /*refresh = document.createElement("a")
  refresh.href = "#"
  refresh.textContent = "[rf2]"
  refreshbox.appendChild(refresh)
  refresh.onclick = function(evt) {
    var l_fetching = 0
    for (var board of boards_list) {
      l_fetching += refresh_list2[board]
    }
    fetching = l_fetching
    fetching_el.style.display=""
    //katalog_element_get(6) //"games"
    for (var board = 0; board < boards_list.length; board++) {
      if (refresh_list2[board]) {
        katalog_element_get(board)
      }
    }
    evt.stopPropagation();evt.preventDefault();return false;
  }*/
  
  /*
  var all_show = document.createElement("a")
  all_show.href = "#"
  all_show.textContent = "[peek]"
  refreshbox.appendChild(all_show)
  all_show.onclick = function(evt) {
    //alert(JSON.stringify(board_new))
    board_peek()
    evt.stopPropagation();evt.preventDefault();return false;
  }*/
  
  all_show = document.createElement("a")
  all_show.href = "#"
  all_show.textContent = "[merge]"
  refreshbox.appendChild(all_show)
  all_show.onclick = function(evt) {
    katalog_merge()
    evt.stopPropagation();evt.preventDefault();return false;
  }
  
  for (var i = 0; i < boards_list.length; i++) {
    var board = boards_list[i]
    
    var space = document.createTextNode(" ")
    //var space = document.createTextNode("\u200B")
    //var space = document.createElement("wbr")
    refreshbox.appendChild(space)
    
    var boardel = document.createElement("a")
    boardel.href = "/" + board + "/"
    //boardel.textContent = board
    
    var b = board_new[i]
    var p = 0
    var m = 0
    
    if (b) for (var j = 0; j < b.length; j++) {
      if (b[j][0] == 2) {
        m++
      } else {
        p++
      }
    }
    
    var name = boards_list[i]
    if (p) name += "(" + p + ")"
    if (m) name += "(-" + m + ")"
    boardel.textContent = name
    
    //games.style.whiteSpace = "nowrap"
    refreshbox.appendChild(boardel)
    //boardel.onclick = click_board
    
    board_el_all[i] = boardel
  }
  
  fetching_el = document.createElement("span")
  fetching_el.textContent = "..."
  fetching_el.style.display="none"
  refreshbox.appendChild(fetching_el)
  
  //var games = document.createElement("a")
  //games.href = "/games/"
  //games.textContent = "/games/"
  //refreshbox.appendChild(games)
  ////games.onclick = parse_katalog
  //games.onclick = function(evt) {
  //  evt.stopPropagation();evt.preventDefault();return false;
  //}
  
  board_peek()
  
}

function board_peek() {
  refreshbox_peek.innerHTML = ""
  for (var board = 0; board < board_new.length; board++ ) {
    var b = board_new[board]
    if (!b) continue
    
    var katalog_old = katalog_get_old(board)
    if (!katalog_old) continue
    
    for (var entry of b) {
      if (entry[0] == 0) {
        //alert("NOT DONE YET")
        var thread_id = entry[1]
        var title = entry[3]
        var how_many_posts = entry[2]
        
        var div = document.createElement("div")
        refreshbox_peek.appendChild(div)
        var a = document.createElement("a")
        div.appendChild(a)
        a.href = "/" + boards_list[board] + "/kareha.pl/" +  thread_id + "/l50"
        //a.href = "#"
        
        a.textContent = "/" + boards_list[board] + "/" + title + "(NEW:" + how_many_posts + ")"
        
      } else if (entry[0] == 1) {
        var katalog_entry = katalog_old[entry[1]]
        
        var thread_id = katalog_entry[0]
        var title = katalog_entry[3]
        var how_many_posts = entry[2] - katalog_entry[2]
        
        var div = document.createElement("div")
        refreshbox_peek.appendChild(div)
        var a = document.createElement("a")
        div.appendChild(a)
        a.href = "/" + boards_list[board] + "/kareha.pl/" +  thread_id + "/l50"
        a.textContent = "/" + boards_list[board] + "/" + title + "(" + how_many_posts + ")"
      } if (entry[0] == 2) {
        //alert("NOT DONE YET (deleted)")
        var katalog_entry = katalog_old[entry[1]]
        
        var thread_id = katalog_entry[0]
        var title = katalog_entry[3]
        var how_many_posts = katalog_entry[2]
        
        var div = document.createElement("div")
        refreshbox_peek.appendChild(div)
        var a = document.createElement("a")
        div.appendChild(a)
        a.href = "/" + boards_list[board] + "/kareha.pl/" +  thread_id + "/l50"
        a.textContent = "/" + boards_list[board] + "/" + title + "(DEL:" + how_many_posts + ")"
      }
    }
    
    
    
    //a.href 
    
    
    
    
  }
  
}

function board_redraw() {
  GM_setValue("4c--board_new", JSON.stringify(board_new))
  
  for (var i = 0; i < boards_list.length; i++ ) {
    var b = board_new[i]
    var p = 0
    var m = 0
    if (b) for (var j = 0; j < b.length; j++) {
      if (b[j][0] == 2) {
      m++
      } else {
      p++
      }
    }
    
    var name = boards_list[i]
    if (p) name += "(" + p + ")"
    if (m) name += "(-" + m + ")"
    board_el_all[i].textContent = name
  }
  if (fetching) {
    fetching_el.style.display = ""
  } else {
    fetching_el.style.display = "none"
  }
  
  if (!fetching) {
    board_peek()
  }
}

function katalog_merge() {
  for (var board = 0; board < board_new.length; board++ ) {
    var b = board_new[board]
    if (!b) continue
    
    var katalog_old = katalog_get_old(board)
    if (!katalog_old) continue
    
    for (var entry of b) {
      if (entry[0] == 0) {
        //new thread
        if (katalog_old[katalog_old.length - 1][0] >= entry[1]) {
          //I assume this will only ever happen if some thread will be moved from some other board
          
          //if it is already in the old_katalog, this is not an issue in the slightest
          //overwise, yeah, ring the bell
          //LATER: I should walk through the entire old katalog and check if it is present or not, but I'm lazy right now
          //this will break only if there are two threads added at once, and you merge them from an other tab. Quite unlikely
          if (katalog_old[katalog_old.length - 1][0] == entry[1]) {
            continue;
          } else {
            alert("two or more threads at once, oh no")
            return
          }
        }
        var new_entry = [entry[1], 1, entry[2], entry[3]]
        katalog_old.push(new_entry)
      } else if (entry[0] == 1) {
        //new replies in an existing thread
        katalog_old[entry[1]][2] = entry[2]
      } else if (entry[0] == 2) {
        //deleted trhead
        katalog_old[entry[1]][1] = 0
      }
    }

    board_new[board] = null

    katalog_set_old(board)
  }
  
  board_redraw()
}


function katalog_element_get(board) {
  var xmlhttp = new XMLHttpRequest();
  var address_full = "https://4-ch.net/" + boards_list[board] + "/subback.html"
  
  xmlhttp.open("GET", address_full, true)
  
  if (board_is_shift_jis[board]) {
    xmlhttp.responseType = 'arraybuffer'
  }
  
  xmlhttp.onload = function(e) {
    var response = ""
    
    if (board_is_shift_jis[board]) {
      var uInt8Array = new Uint8Array(this.response)
      var codepage = "shift_jis"
      var shift_jis = new TextDecoder(codepage, {fatal: true})
      response = shift_jis.decode(uInt8Array)
    } else {
      response = this.responseText
    }
    
    response = response.split(/<body[^>]*>((?:.|\n|\r)*)<\/body>/i)[1]
    var page = document.createElement('div')
    page.innerHTML = response
    page = document.evaluate('//*[@id="oldthreadlist"]', page, null, 9, null).singleNodeValue
    katalog_parse(board, page)
  }
  
  xmlhttp.send();
  
}

function katalog_parse(board, tl) {
  //var katalog_element = get_katalog_element("games")
  
  //var tl = katalog_element.getElementById("oldthreadlist")
  //var tl = katalog_element_get("games")
  var tr_all = tl.getElementsByTagName("tr")

  var katalog = new Array(tr_all.length-1)
  var ii = 0
  for (var i = tr_all.length - 1; i != 0; i--) {
    var tr = tr_all[i]

    var a_all = tr.getElementsByTagName("a")

    var a0 = a_all[0]
    var thread_url = a0.getAttribute('href')
    var thread_num_str = thread_url.split("/")[3]
    var thread_num = parseInt(thread_num_str)

    var thread_title = a0.textContent

    var a1 = a_all[1]
    var thread_posts = parseInt(a1.textContent)
    katalog[ii] = [thread_num, 1, thread_posts, thread_title]


    var j = ii;
    if (j > 0) do {
      //from oldest to newest
      if (katalog[j][0] > katalog[j-1][0]) break
      var temp = katalog[j]
      katalog[j] = katalog[j-1]
      katalog[j-1] = temp
    } while (--j > 0)

    ii++
  }
  
  katalog_all[board] = katalog
  
  //alert(katalog[0][3])
  //alert(JSON.stringify(katalog))
  
  katalog_compare(board)
}

function katalog_compare(board) {
  //alert("got here")
  
  var katalog_old = katalog_get_old(board)
  var katalog = katalog_all[board]
  
  if (!katalog_old) {
    katalog_all_old[board] = katalog
    katalog_set_old(board)
    return
  }
  
  var changed = []
  
  if (!katalog || !katalog_old || katalog.length == 0 || katalog_old.length == 0) {
    alert("something went wrong in katalog_compare")
    return
  }
  
  var i = 0
  var o = 0
  while (true) {
    var ii = katalog[i]
    var oo = katalog_old[o]
    if (ii[0] == oo[0]) {
      if (ii[2] != oo[2]) {
        changed.push([1, o, ii[2]])
      }
      i++
      o++
    } else if (ii[0] > oo[0]) {
      if (oo[1]) {
        changed.push([2, o])
      }
      o++
    } else {
      changed.push([0, ii[0], ii[2], ii[3]])
      i++
    }
    
    if (i >= katalog.length) {
      while (o < katalog_old.length) {
        oo = katalog_old[o]
        if (oo[1]) {
          changed.push([2, o])
        }
        o++
      }
      break
    }
    
    if (o >= katalog_old.length) {
      while (i < katalog.length) {
        ii = katalog[i]
        changed.push([0, ii[0], ii[2], ii[3]])
        i++
      }
      break
    }
    
  }
  
  if (changed.length) {
    board_new[board] = changed
  }
  
  //alert("hi")
  fetching--
  board_redraw()
  
  //alert("hi")
  //alert(katalog[0][3])
  
  //katalog_all_old[board] = katalog
  //katalog_set_old(board)
}

function katalog_set_old(board) {
  var katalog = katalog_all_old[board]
  var res = ""
  var i = 0
  for (ka of katalog) {
    res += katalog[i][0] + "," + katalog[i][1] + "," + katalog[i][2] + "," + katalog[i][3] + "\n"
    i++
  }
  
  GM_setValue(boards_list[board], res)
}

function katalog_get_old(board) {
  
  var res = katalog_all_old[board]
  if (res !== undefined) return res
  
  res = GM_getValue(boards_list[board])
  if (res === undefined) return res
  
  var res2 = []
  res = res.split("\n")
  for (var line of res) {
    if (line) {
      var parsed_line = []
      var j = line.indexOf(",")
      parsed_line.push(parseInt(line.substring(0,j)))
      j++
      var k = line.indexOf(",",j)
      parsed_line.push(parseInt(line.substring(j,k)))
      j = k+1
      k = line.indexOf(",",j)
      parsed_line.push(parseInt(line.substring(j,k)))
      parsed_line.push(line.substring(k+1))
      
      res2.push(parsed_line)
    }
  }
  
  katalog_all_old[board] = res2
  
  return res2
}

function error() {
  alert("4-ch.net userscript broke")
}

start()