// ==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==

"use strict";

const 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
// if fetching > 0, we are currently grabbing katalog data for some boards
var fetch = null
// this is the [fetch] button

var katalog_all = new Array(boards_list.length)
//katalog_all is recently fetched and parsed katalog. Array of array of thread data.
var katalog_all_old = new Array(boards_list.length)
//katalog_all_old is previous version of katalog, we keep it to compare old amount of replies to new one.
//katalog elements are [thread_id, wasnt_deleted_yet, amount_of_replies, thread_title]
const kat_thread_id = 0, kat_wasnt_deleted_yet = 1, kat_amount_of_replies = 2, kat_thread_title = 3

var changes_all = new Array(boards_list.length)
//changes_all is 
//changes elements are [changes_type, the rest]
//if changes_type == 0, this is a "new thread" element, and the rest are [thread_id, amount_of_replies, thread_title]
//if changes_type == 1, this is a "updated thread", and the rest are [index_in_katalog, new_amount_of_replies]
//if changes_type == 2, this is a "deleted thread", and the rest are [index_in_katalog]
const changes_type_new = 0, changes_type_updated = 1, changes_type_deleted = 2
const changes_type = 0, changes_thread_id = 1, changes_amount_of_replies = 2, changes_thread_title = 3, changes_index_in_katalog = 1, changes_new_amount_of_replies = 2

var board_el_all = new Array(boards_list.length)

var refreshbox_peek = null

var sync
// sync is array of numbers from 0 to 255.
// first one indicates if 4-c--changes was updated in another tab
// the rest indicates if any of the katalog was updated in another tab.

//TODO
// *) The most important one is faving and hiding threads. The rest is feature creep.
// *) And maybe keep track of last updated threads, I sometimes click merge too fast and regret doing it.
// *) Maybe move [merge] button somewhere. And add merge to each thread. Add [mark all as read]
// *) Add [options-]. Add list of: List board / Follow board / Ignore unfaved threads
// *) Display thread as /dqn/1:Thread Name, show its position so that I can bump it in time.
// This will require changing the way threads are currently stored, will need  to store their position too.
// Oh, I know, I can reuse kat_wasn't deleted yet, when 1 is first, 2 is second, etc, and 3 is deleted.
// *) Options screen is a bunch of /board/      [_][X][_] checkboxes. Top row is description and will set all boards.
// *) Option to show current thread position on board.
// *) Option to autodelete unused threads.
// *) A way to open katalog without actually going to the board of interest.
// *) Save options as json, and all faved/hidden threads as json, so that the user can paste all of it into a single text field for the user to copypaste.
// *) Get rid of refresh_list1
// *) Add a way to show faved threads even if there are no new posts.
// *) Add the date to the sync, and compare the last fetch date. I need to stop old fetch from overwriting new fetch.

// I just need to add buttons [refresh][by new-][fav first-][show hidden-][board list-]
// [mark all as read]
// and [thread list style:1]

function start() {
  var stylebox = document.getElementById("stylebox")
  if (!stylebox) {
    return
  }
  stylebox.style.display="none"
  
  sync = sync_load()
  
  var l_changes_all = GM_getValue("4-c--changes")
  if (l_changes_all) {
    changes_all = JSON.parse(l_changes_all)
  }

  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_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) {
    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;
  }
  
  fetch = document.createElement("a")
  fetch.href = "#"
  fetch.textContent = "[fetch]"
  refreshbox.appendChild(fetch)
  fetch.onclick = function(evt) {
    if (fetching != 0) {
      evt.stopPropagation();evt.preventDefault();return false;
    }
    var l_fetching = 0
    for (var is_refreshed of refresh_list1) {
      l_fetching += is_refreshed
    }
    fetching = l_fetching
    fetch.textContent = "[fetching...]"
    for (var board = 0; board < boards_list.length; board++) {
      if (refresh_list1[board]) {
        katalog_request(board)
      }
    }
    evt.stopPropagation();evt.preventDefault();return false;
  }
  
  var merge = document.createElement("a")
  merge.href = "#"
  merge.textContent = "[merge]"
  refreshbox.appendChild(merge)
  merge.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]
    
    refreshbox.appendChild(document.createTextNode(" "))
    
    var boardel = document.createElement("a")
    boardel.href = "/" + board + "/"
    
    var b = changes_all[i]
    var updated = 0
    var deleted = 0
    if (b) for (var j = 0; j < b.length; j++) {
      if (b[j][changes_type] == changes_type_deleted) {
        deleted++
      } else {
        updated++
      }
    }
    
    var name = boards_list[i]
    if (updated) name += "(" + updated + ")"
    if (deleted) name += "(-" + deleted + ")"
    boardel.textContent = name
    
    refreshbox.appendChild(boardel)
    
    board_el_all[i] = boardel
  }
  
  document.addEventListener("focus", function(evt) {
    var new_sync = sync_load()
    
    for (var board = 0; board < boards_list.length; board++ ) {
      if (sync[board+1] != new_sync[board+1]) {
        katalog_all_old[board] = null
        katalog_get_old(board)
      }
    }
    
    if (sync[0] != new_sync[0]) {
      changes_all = JSON.parse(GM_getValue("4-c--changes"))
      board_redraw()
    }
    
    sync = new_sync
  })
  
  inject()
  
  board_peek()
  
}

function sync_load() {
  var new_sync
  var l_sync = GM_getValue("4-c--sync")
  if (l_sync) {
    new_sync = JSON.parse(l_sync)
    if (new_sync.length != (boards_list.length+1)) new_sync = null
  }
  if (!new_sync) {
    new_sync = new Array(boards_list.length+1)
    for (var i = 0; i < (boards_list.length+1); i++ ) {
      new_sync[i] = 0
    }
    GM_setValue("4-c--sync", JSON.stringify(new_sync))
  }
  return new_sync
}

function sync_save() {
  GM_setValue("4-c--sync", JSON.stringify(sync))
}

function sync_add(index) {
  sync[index]++
  if (sync[index] > 255) sync[index] = 0
}

function inject() {
  var threads = document.getElementsByClassName("thread")
  for (var thread_i = 0; thread_i < threads.length; thread_i++) {
    let thread = threads[thread_i]
    var threadlinks = thread.getElementsByClassName("threadlinks")
    if (threadlinks.length == 0) continue
    threadlinks = threadlinks[0]
    if (threadlinks.getElementsByTagName("a").length == 0) continue
    
    let favbottom = document.createElement("a")
    favbottom.innerText = "[Fav]"
    favbottom.href = "#"
    
    let hidebottom = document.createElement("a")
    hidebottom.innerText = "[Hide]"
    hidebottom.href = "#"
    
    threadlinks.appendChild(document.createTextNode(" "))
    threadlinks.appendChild(favbottom)
    threadlinks.appendChild(document.createTextNode(" "))
    threadlinks.appendChild(hidebottom)
    
    var threadnavigation = thread.getElementsByClassName("threadnavigation")
    if (threadnavigation.length == 0) continue
    threadnavigation = threadnavigation[0]
    
    let favtop = document.createElement("a")
    favtop.innerText = "[Fav]"
    favtop.href = "#"
    
    let hidetop = document.createElement("a")
    hidetop.innerText = "[Hide]"
    hidetop.href = "#"
    
    hidetop.onclick = hidebottom.onclick = function(evt) {
      if (hidetop.textContent == "[Hide]") {
        thread.style.height = "1.25em"
        thread.style.overflow = "hidden"
        hidetop.textContent = "[Unhide]"
      } else {
        thread.style.height = ""
        thread.style.overflow = ""
        hidetop.textContent = "[Hide]"
      }

      evt.stopPropagation();evt.preventDefault();return false;
    }
    
    add_before(threadnavigation.firstChild, hidetop)
    add_before(threadnavigation.firstChild, document.createTextNode(" "))
    add_before(threadnavigation.firstChild, favtop)
    add_before(threadnavigation.firstChild, document.createTextNode(" "))
    
  }
}

function board_peek() {
  refreshbox_peek.innerHTML = ""
  for (var board = 0; board < boards_list.length; board++ ) {
    var changes = changes_all[board]
    if (!changes) continue
    
    var katalog_old = katalog_get_old(board)
    if (!katalog_old) continue
    
    for (var change of changes) {
      var thread_id
      var title
      var how_many_posts
      var indicator
      
      var posts_before
      var posts_now
      
      var element_type = change[0]
      
      if (element_type == changes_type_new) {
        thread_id = change[changes_thread_id]
        title = change[changes_thread_title]
        how_many_posts = change[changes_amount_of_replies]
        indicator = "NEW:"
        
        posts_before = 0
        posts_now = how_many_posts
        
      } else if (element_type == changes_type_updated) {
        var katalog_entry = katalog_old[change[changes_index_in_katalog]]
        
        thread_id = katalog_entry[kat_thread_id]
        title = katalog_entry[kat_thread_title]
        how_many_posts = change[changes_amount_of_replies] - katalog_entry[kat_amount_of_replies]
        indicator = ""
        
        posts_before = katalog_entry[kat_amount_of_replies]
        posts_now = change[changes_amount_of_replies]
        

      } else if (element_type == changes_type_deleted) {
        var katalog_entry = katalog_old[entry[changes_index_in_katalog]]
        
        thread_id = katalog_entry[kat_thread_id]
        title = katalog_entry[kat_thread_title]
        how_many_posts = katalog_entry[kat_amount_of_replies]
        indicator = "DEL:"
        
        posts_before = katalog_entry[kat_amount_of_replies]
        posts_now = change[kat_amount_of_replies]
      }
      
      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 + "(" + indicator + how_many_posts + ")"
      
      var space = document.createTextNode(" ")
      div.appendChild(space)
      
      var a_newtab = document.createElement("a")
      div.appendChild(a_newtab)
      a_newtab.href = "/" + boards_list[board] + "/kareha.pl/" +  thread_id + "/l50"
      a_newtab.setAttribute("target", "_blank")
      a_newtab.textContent = "[newtab]"
      
      if (element_type == changes_type_deleted) continue
      
      div.appendChild(document.createTextNode(" "))
      
      let a_peek = document.createElement("a")
      div.appendChild(a_peek)
      a_peek.href = "#"
      a_peek.textContent = "[peek-]"
      
      let a_peek_div = document.createElement("div")
      a_peek_div.style.backgroundColor="#EFEFEF"
      div.appendChild(a_peek_div)
      
      let a_peek_board = board
      let a_peek_url
      if (how_many_posts == 1) {
        a_peek_url = "https://4-ch.net/" + boards_list[board] + "/kareha.pl/" +  thread_id + "/" + posts_now
      } else {
        a_peek_url = "https://4-ch.net/" + boards_list[board] + "/kareha.pl/" +  thread_id + "/n" + (posts_before+1) + "-" + posts_now
      }
        
      a_peek.onclick = function(evt) {
        if (a_peek.textContent == "[peek-]") {
          a_peek.textContent = "[peek+]"
          thread_request(a_peek, a_peek_div, a_peek_url)
        } else {
          a_peek.textContent = "[peek-]"
          a_peek_div.innerHTML = ""
        }
        evt.stopPropagation();evt.preventDefault();return false;
      }
      
      
    }
    
  }
  
}

function thread_request(a_peek, a_peek_div, url) {
  var xmlhttp = new XMLHttpRequest();
  var address_full = url
  
  xmlhttp.open("GET", address_full, true)
  
  var board = 0 //LATER: need to do something about shift-jis being badly supported by TextDecoder
  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('//*[@class="allreplies"]', page, null, 9, null).singleNodeValue
    a_peek_div.innerHTML = page.innerHTML
  }
  
  xmlhttp.send();
}

function board_redraw() {
  for (var i = 0; i < boards_list.length; i++ ) {
    var b = changes_all[i]
    var updated = 0
    var deleted = 0
    if (b) for (var j = 0; j < b.length; j++) {
      if (b[j][changes_type] == changes_type_deleted) {
        deleted++
      } else {
        updated++
      }
    }
    
    var name = boards_list[i]
    if (updated) name += "(" + updated + ")"
    if (deleted) name += "(-" + deleted + ")"
    board_el_all[i].textContent = name
  }
  
  if (fetching == 0) {
    fetch.textContent = "[fetch]"
    GM_setValue("4-c--changes", JSON.stringify(changes_all))
    sync_add(0)
    sync_save()
  }
  
  board_peek()
}

function katalog_merge() {
  for (var board = 0; board < boards_list.length; board++ ) { //LATER
    var changes = changes_all[board]
    if (!changes) continue
    
    var katalog_old = katalog_get_old(board)
    if (!katalog_old) continue
    
    for (var change of changes) {
      if (change[changes_type] == changes_type_new) {
        if (katalog_old[katalog_old.length - 1][kat_thread_id] >= change[changes_thread_id]) {
          //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][kat_thread_id] == change[changes_thread_id]) {
            continue;
          } else {
            alert("two or more threads at once, oh no")
            return
          }
        }
        var new_entry = [change[changes_thread_id], 1, change[changes_amount_of_replies], change[changes_thread_title]]
        katalog_old.push(new_entry)
        
      } else if (change[changes_type] == changes_type_updated) {
        katalog_old[change[changes_thread_id]][kat_amount_of_replies] = change[changes_amount_of_replies]
        
      } else if (change[changes_type] == changes_type_deleted) {
        katalog_old[change[changes_thread_id]][kat_wasnt_deleted_yet] = 0
      }
    }

    changes_all[board] = null
    sync_add(board+1)

    katalog_set_old(board)
  }
  
  GM_setValue("4-c--changes", JSON.stringify(changes_all))
  sync_add(0)
  //sync_add(1)
  sync_save()
  board_redraw()
}

function katalog_request(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 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[kat_thread_id] == oo[kat_thread_id]) {
      if (ii[kat_amount_of_replies] != oo[kat_amount_of_replies]) {
        changed.push([changes_type_updated, o, ii[kat_amount_of_replies]])
      }
      i++
      o++
    } else if (ii[kat_thread_id] > oo[kat_thread_id]) {
      if (oo[kat_wasnt_deleted_yet]) {
        changed.push([changes_type_deleted, o])
      }
      o++
    } else {
      changed.push([changes_type_new, ii[kat_thread_id], ii[kat_amount_of_replies], ii[kat_thread_title]])
      i++
    }
    
    if (i >= katalog.length) {
      while (o < katalog_old.length) {
        oo = katalog_old[o]
        if (oo[1]) {
          changed.push([changes_type_deleted, o])
        }
        o++
      }
      break
    }
    
    if (o >= katalog_old.length) {
      while (i < katalog.length) {
        ii = katalog[i]
        changed.push([changes_type_new, ii[kat_thread_id], ii[kat_amount_of_replies], ii[kat_thread_title]])
        i++
      }
      break
    }
    
  }
  
  if (changed.length) {
    changes_all[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 (var ka of katalog) {
    res += katalog[i][kat_thread_id] + "," + katalog[i][kat_wasnt_deleted_yet] + "," + katalog[i][kat_amount_of_replies] + "," + katalog[i][kat_thread_title] + "\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")
}

function add_after(referenceNode, newNode) {
  referenceNode.parentNode.insertBefore(newNode, referenceNode.nextSibling)
}

function add_before(referenceNode, newNode) {
  referenceNode.parentNode.insertBefore(newNode, referenceNode)
}

start()