// ==UserScript==
// @name    Publication Auto PDF
// @name:zh-CN  SCI文献PDF直达
// @version 0.3
// @author  sincostandx
// @description Automatically jumps to PDF when you visit a journal article abstract page. Also includes a utility to copy or download citation info.
// @description:zh-CN  访问SCI文献摘要页时自动跳转至PDF，附带文献摘录工具
// @include http*://www.sciencedirect.com/science/article/*
// @include http*://pubs.acs.org/doi/*
// @include http*://www.tandfonline.com/doi/abs/*
// @include http*://www.beilstein-journals.org/*
// @include http*://onlinelibrary.wiley.com/doi/*
// @include http*://www.eurekaselect.com/*/article*
// @include http*://pubs.rsc.org/en/Content/*
// @include http*://link.springer.com/article*
// @include http*://aip.scitation.org/doi/10*
// @include http*://aip.scitation.org/doi/abs/10*
// @include http*://www.nature.com/articles*
// @include http*://science.sciencemag.org/content*
// @include http*://journals.aps.org/*/abstract/10*
// @include http*://www.nrcresearchpress.com/doi/10*
// @include http*://iopscience.iop.org/article/10*
// @exclude *.pdf
// @grant   GM.xmlHttpRequest
// @grant   GM.getValue
// @grant   GM.setValue
// @run-at  document-start
// @namespace https://greasyfork.org/users/171198
// @downloadURL none
// ==/UserScript==

"use strict";

var tit=null; //title
var doi=null;
var pdf=null; //pdf url

var sty=""; // citation text style

if (location.href.includes("pubs.acs.org/doi/abs/"))
  pdf=location.href.replace("/abs/","/pdf/"); // Works for ACS journals
else if (location.href.includes("pubs.acs.org/doi/10."))
  pdf=location.href.replace("/doi/","/doi/pdf/");
else if (location.href.includes("journals.aps.org/") && location.href.includes("abstract/10."))
  pdf=location.href.replace("/abstract/","/pdf/");


const jump = window.history.length<=1 || sessionStorage.getItem(location.pathname) === null;
sessionStorage.setItem(location.pathname,"1");

if (jump && pdf !== null && location.href !== pdf) {
  window.stop();
  location.href=pdf;
} else {
  checkLoaded();
}

function checkLoaded() {
  if (document.body !== null && document.body.innerHTML.length !== 0)
    loadMeta();
  else
    setTimeout(checkLoaded,100);
}

function loadMeta() {
  const titmeta=["dc.title","citation_title"];
  const doimeta=["citation_doi","dc.identifier","dc.source"];
  const l=document.getElementsByTagName("meta");
  for(let i=0; i<l.length; ++i) {
    let n=l[i].getAttribute("name");
    if (n===null)
      continue;
  	n=n.toLowerCase();
    if (tit===null && titmeta.includes(n)) {
      tit = l[i].getAttribute("content");
      continue;
    }
    if (doi===null && doimeta.includes(n)) {
      const d = l[i].getAttribute("content");
      if (d.includes("10.")) {
        if (d.includes("doi")) {
          doi=d.slice(d.indexOf("10."));
        } else {
          doi=d;
        }
        continue;
      }
    }
    if (pdf===null && n === "citation_pdf_url")
      pdf = l[i].getAttribute("content");
  }
  if (jump && pdf !== null && location.href !== pdf) {
    window.stop();
    if (location.href.includes("sciencedirect.com")) {
      loadElsevierPDF();
    } else {
	    location.href = pdf;
    }
  } else {
    if (doi===null) return;
    if (tit===null) tit="Unknown Title";
    toolbox(tit,doi,pdf);
  }
}

// newbr, newinput, newtag are util functions to create toolbox elements.
function newbr(parent) {
  parent.appendChild(document.createElement("br"));
}

function newinput(parent,type,value,onclick) {
  const i = document.createElement("input");
  i.type = type;
  i.value = value;
  if (onclick!==null)
    i.addEventListener("click", onclick, false);
  i.className = "toolbox";
  parent.appendChild(i);
  return i;
}

function newtag(parent,tag,text) {
  const i = document.createElement(tag);
  if (text !== null)
    i.innerHTML = text;
  i.className = "toolbox";
  parent.appendChild(i);
  return i;
}

function loadElsevierPDF() {
  const xhr = new XMLHttpRequest();
  xhr.onreadystatechange = function() {
    try {
      if (this.readyState == 4 && this.status == 200) {
        const doc = new DOMParser().parseFromString(this.response,"text/html");
        const href = doc.querySelector("#redirect-message > p > a").href;
        sessionStorage.setItem(doi,href);
        location.href = href;
      }
    }
    catch(e) {
      console.log(e);
      location.href = pdf;
    }
  }
  xhr.open("GET", pdf, true);
  xhr.send();
}

function toolbox(tit,doi,pdf) {
  const div = document.createElement("div");
  div.style="z-index:2147483646;position:fixed;right:10px;top:50%;transform: translate(0, -50%);border:2px groove black;background:white;box-shadow:6px 6px 3px grey;";

  const sheet = document.createElement("style")
  sheet.innerHTML = ".toolbox{font-size: 10pt;font-family: sans-serif;margin:0;padding:0;margin-bottom:2px;display:initial;}input.toolbox,select.toolbox{background-image: none !important;width: auto;max-height:none}textarea.toolbox,input.toolbox[type=text]{-webkit-box-sizing: border-box;-moz-box-sizing: border-box;box-sizing: border-box;width: 11em;}input.toolbox[type=button]{padding: 2px 8px;}[tooltip]:before {position: absolute;opacity: 0;}[tooltip]:hover:before {content: attr(tooltip);opacity:1;color:black;background:white;padding:2px;border:1px groove black;white-space: nowrap;overflow: hidden;right:0;margin-top:-25pt;}"
  div.appendChild(sheet);
  
  // Hide button
  const hide_btn_parent = newtag(div,"div",null);
  hide_btn_parent.style = "display:flex;justify-content:flex-end;padding-right:10px;";
  const hide_btn = newtag(hide_btn_parent,"a","✖");
  hide_btn.style = "cursor:pointer;font-size:large;text-decoration:none;";
  hide_btn.addEventListener("click", function(){div.remove();}, false);
  
  // DOI textbox and copy button
  const txt_doi = newinput(div,"text",doi,null);
  newbr(div);
  newinput(div,"button","Copy",function(){txt_doi.select();document.execCommand("Copy");});
  newbr(div);newbr(div);
  
  // info textbox and copy button
  const info = tit+"\t"+doi;
  const txt_inf = newinput(div,"text",info,null);
  newbr(div);
  newinput(div,"button","Copy",function(){txt_inf.select();document.execCommand("Copy");});
  newbr(div);newbr(div);
  
  // bibtex button
  const txt_bib = newtag(div,"textarea",null);
  txt_bib.style.display = "none";
  txt_bib.style.resize = "none";
  newbr(div);
  const btn_bib = newinput(div,"button","Copy BibTeX",loadBib);
  newbr(div);
  function loadBib() {
    btn_bib.disabled = true;
    btn_bib.value = "Loading";
    GM.xmlHttpRequest({
      method: "GET",
      url: "https://dx.doi.org/" + doi,
      headers: {
        "Accept": "application/x-bibtex"
      },
      onload: function(response) {
        if (response.readyState == 4 && response.status == 200) {
          const bib = response.responseText;
          txt_bib.value = bib;
          txt_bib.style.display = "";
					txt_bib.select();
          document.execCommand("Copy");
          btn_bib.value = "Copy BibTeX";
        } else {
          btn_bib.value = "Reload BibTeX";
        }
        btn_bib.disabled = false;
      },
      onerror: function(response) {
        btn_bib.value = "Reload BibTeX";
        btn_bib.disabled = false;
      }
    });
  }
  // Text button
  const btn_txt = newinput(div,"button","Copy Text",loadTxt);
  function loadTxt() {
    if (sty==="") {
      setstyle();
      return;
    }
    btn_txt.disabled = true;
    btn_txt.value = "Loading";
    GM.xmlHttpRequest({
      method: "GET",
      url: "https://dx.doi.org/" + doi,
      headers: {
        "Accept": "text/x-bibliography; style="+sty
      },
      onload: function(response) {
        if (response.readyState == 4 && response.status == 200) {
          const bib = response.responseText;
          txt_bib.value = bib;
          txt_bib.style.display = "";
					txt_bib.select();
          document.execCommand("Copy");
          btn_txt.value = "Copy Text";
        } else {
          btn_txt.value = "Reload Text";
        }
        btn_txt.disabled = false;
      },
      onerror: function(response) {
        btn_txt.value = "Reload Text";
        btn_txt.disabled = false;
      }
    });
  }
  // text style link
  const stylink = newtag(div,"a","Style");
  stylink.addEventListener("click",setstyle,false);
  stylink.style.cursor = "pointer";
  newbr(div);
  
  function setstyle() {
    const div = document.createElement("div");
    div.style="z-index:2147483647;position:fixed;left:50%;top:50%;transform:translate(-50%, -50%);border:2px groove black;background:white;padding:20px;box-shadow:10px 10px 5px grey;";

    newtag(div,"h3","Choose a citation style for text references:").style.fontSize="medium";
    const sel = newtag(div,"select",null);
    sel.size = 15;
    sel.style.minWidth="600px";
    newbr(div);newbr(div);
    newtag(div,"p","This citation style will be saved as default.");

    const btns = newtag(div,"div",null);
    btns.style.textAlign = "center";
    // OK button
    newinput(btns,"button","OK",function() {
      sty = sel.value;
      GM.setValue("sty",sty);
      document.body.removeChild(div);
      loadTxt();
    });
    // cancel button
    newinput(btns,"button","Cancel",function(){document.body.removeChild(div);}).style.marginLeft = "1em";

    // load styles
    GM.xmlHttpRequest({
      method: "GET",
      url: "https://citation.crosscite.org/styles",
      onload: function(response) {
        if (response.readyState == 4 && response.status == 200) {
          const l = JSON.parse(response.responseText);
          for (let i=0; i<l.length; i++) {
            const x = document.createElement("option");
            x.text = l[i];
            sel.add(x);
          }
          if (sty!=="")
            sel.value = sty;
          else
            sel.selectedIndex = 0;
        } else {
          alert("Cannot load style list.");
          document.body.removeChild(div);
        }
      },
      onerror: function(response) {
        alert("Cannot load style list.");
        document.body.removeChild(div);
      }
    });

    document.body.appendChild(div);
  }
  
  // RIS link
  const rislink = newtag(div,"a","Download RIS");
  rislink.addEventListener("click",loadris);
  rislink.style.cursor = "pointer";
  function loadris() {
    rislink.removeEventListener("click",loadris);
    GM.xmlHttpRequest({
      method: "GET",
      url: "https://dx.doi.org/" + doi,
      headers: {
        "Accept": "application/x-research-info-systems"
      },
      onload: function(response) {
        if (response.readyState == 4 && response.status == 200) {
          const ris = response.responseText;
          const blob = new Blob([ris], {type: "octet/stream"});
          const url  = URL.createObjectURL(blob);
          rislink.href = url;
          rislink.download = doi.replace("/","@")+".ris";
          rislink.click();
        } else {
          alert("Unable to download RIS.");
          rislink.addEventListener("click",loadris);
        }
        btn_txt.disabled = false;
      },
      onerror: function(response) {
        alert("Unable to download RIS.");
        rislink.addEventListener("click",loadris);
      }
    });
  }

  newbr(div);newbr(div);
  
  // PDF link
  if (pdf !== null) {
    const pdflink = newtag(div,"a","PDF");
    if (location.href.includes("sciencedirect.com")) {
      const href = sessionStorage.getItem(doi);
      if (href !== null) {
        pdflink.href = href;
      } else {
      	pdflink.addEventListener("click",loadElsevierPDF);
      	pdflink.style.cursor = "pointer";
      }
    } else {
      pdflink.href = pdf;
    }
    newbr(div);newbr(div);
  }
  
  // Sci-Hub link
  const scihubURL = "https://sci-hub.tw/";
  const scihublink = newtag(div,"a","Sci-Hub");
  if (doi !== null)
  	scihublink.href = scihubURL + doi;
  else
    scihublink.href = scihubURL + location.href;
  newbr(div);newbr(div);
  
  document.body.appendChild(div);
  
  GM.getValue("sty","").then(function(v){sty=v;stylink.setAttribute("tooltip",v==="" ? "You have not set a reference style" : "Current style: "+v);});
}