/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

ChromeUtils.import("resource://gre/modules/Services.jsm");
ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
ChromeUtils.import("resource://gre/modules/osfile.jsm");

// This component is used for handling dragover and drop of urls.
//
// It checks to see whether a drop of a url is allowed. For instance, a url
// cannot be dropped if it is not a valid uri or the source of the drag cannot
// access the uri. This prevents, for example, a source document from tricking
// the user into dragging a chrome url.

function ContentAreaDropListener() { };

ContentAreaDropListener.prototype =
{
  classID:          Components.ID("{1f34bc80-1bc7-11d6-a384-d705dd0746fc}"),
  QueryInterface:   ChromeUtils.generateQI([Ci.nsIDroppedLinkHandler]),

  _addLink : function(links, url, name, type)
   {
    links.push({ url, name, type });
  },

  _addLinksFromItem: function(links, dt, i)
  {
    let types = dt.mozTypesAt(i);
    let type, data;

    type = "text/uri-list";
    if (types.contains(type)) {
      data = dt.mozGetDataAt(type, i);
      if (data) {
        let urls = data.split("\n");
        for (let url of urls) {
          // lines beginning with # are comments
          if (url.startsWith("#"))
            continue;
          url = url.replace(/^\s+|\s+$/g, "");
          this._addLink(links, url, url, type);
        }
        return;
      }
    }

    type = "text/x-moz-url";
    if (types.contains(type)) {
      data = dt.mozGetDataAt(type, i);
      if (data) {
        let lines = data.split("\n");
        for (let i = 0, length = lines.length; i < length; i += 2) {
          this._addLink(links, lines[i], lines[i + 1], type);
        }
        return;
      }
    }

    for (let type of ["text/plain", "text/x-moz-text-internal"]) {
      if (types.contains(type)) {
        data = dt.mozGetDataAt(type, i);
        if (data) {
          let lines = data.replace(/^\s+|\s+$/mg, "").split("\n");
          if (!lines.length) {
            return;
          }

          // For plain text, there are 2 cases:
          //   * if there is at least one URI:
          //       Add all URIs, ignoring non-URI lines, so that all URIs
          //       are opened in tabs.
          //   * if there's no URI:
          //       Add the entire text as a single entry, so that the entire
          //       text is searched.
          let hasURI = false;
          let flags = Ci.nsIURIFixup.FIXUP_FLAG_FIX_SCHEME_TYPOS |
              Ci.nsIURIFixup.FIXUP_FLAG_ALLOW_KEYWORD_LOOKUP;
          for (let line of lines) {
            let info = Services.uriFixup.getFixupURIInfo(line, flags);
            if (info.fixedURI) {
              // Use the original line here, and let the caller decide
              // whether to perform fixup or not.
              hasURI = true;
              this._addLink(links, line, line, type);
            }
          }

          if (!hasURI) {
            this._addLink(links, data, data, type);
          }
          return;
        }
      }
    }

    // For shortcuts, we want to check for the file type last, so that the
    // url pointed to in one of the url types is found first before the file
    // type, which points to the actual file.
    let files = dt.files;
    if (files && i < files.length) {
      this._addLink(links, OS.Path.toFileURI(files[i].mozFullPath),
                    files[i].name, "application/x-moz-file");
    }
  },

  _getDropLinks : function (dt)
  {
    let links = [];
    for (let i = 0; i < dt.mozItemCount; i++) {
      this._addLinksFromItem(links, dt, i);
    }
    return links;
  },

  _validateURI: function(dataTransfer, uriString, disallowInherit,
                         triggeringPrincipal)
  {
    if (!uriString)
      return "";

    // Strip leading and trailing whitespace, then try to create a
    // URI from the dropped string. If that succeeds, we're
    // dropping a URI and we need to do a security check to make
    // sure the source document can load the dropped URI.
    uriString = uriString.replace(/^\s*|\s*$/g, '');

    // Apply URI fixup so that this validation prevents bad URIs even if the
    // similar fixup is applied later, especialy fixing typos up will convert
    // non-URI to URI.
    let fixupFlags = Ci.nsIURIFixup.FIXUP_FLAG_FIX_SCHEME_TYPOS |
        Ci.nsIURIFixup.FIXUP_FLAG_ALLOW_KEYWORD_LOOKUP;
    let info = Services.uriFixup.getFixupURIInfo(uriString, fixupFlags);
    if (!info.fixedURI || info.keywordProviderName) {
      // Loading a keyword search should always be fine for all cases.
      return uriString;
    }
    let uri = info.fixedURI;

    let secMan = Cc["@mozilla.org/scriptsecuritymanager;1"].
                   getService(Ci.nsIScriptSecurityManager);
    let flags = secMan.STANDARD;
    if (disallowInherit)
      flags |= secMan.DISALLOW_INHERIT_PRINCIPAL;

    secMan.checkLoadURIWithPrincipal(triggeringPrincipal, uri, flags);

    // Once we validated, return the URI after fixup, instead of the original
    // uriString.
    return uri.spec;
  },

  _getTriggeringPrincipalFromDataTransfer: function(aDataTransfer,
                                                    fallbackToSystemPrincipal)
  {
    let sourceNode = aDataTransfer.mozSourceNode;
    if (sourceNode &&
        (sourceNode.localName !== "browser" ||
         sourceNode.namespaceURI !== "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul")) {
      // Use sourceNode's principal only if the sourceNode is not browser.
      //
      // If sourceNode is browser, the actual triggering principal may be
      // differ than sourceNode's principal, since sourceNode's principal is
      // top level document's one and the drag may be triggered from a frame
      // with different principal.
      if (sourceNode.nodePrincipal) {
        return sourceNode.nodePrincipal;
      }
    }

    // First, fallback to mozTriggeringPrincipalURISpec that is set when the
    // drop comes from another content process.
    let principalURISpec = aDataTransfer.mozTriggeringPrincipalURISpec;
    if (!principalURISpec) {
      // Fallback to either system principal or file principal, supposing
      // the drop comes from outside of the browser, so that drops of file
      // URIs are always allowed.
      //
      // TODO: Investigate and describe the difference between them,
      //       or use only one principal. (Bug 1367038)
      if (fallbackToSystemPrincipal) {
        let secMan = Cc["@mozilla.org/scriptsecuritymanager;1"].
            getService(Ci.nsIScriptSecurityManager);
        return secMan.getSystemPrincipal();
      } else {
        principalURISpec = "file:///";
      }
    }
    let ioService = Cc["@mozilla.org/network/io-service;1"]
        .getService(Ci.nsIIOService);
    let secMan = Cc["@mozilla.org/scriptsecuritymanager;1"].
        getService(Ci.nsIScriptSecurityManager);
    return secMan.createCodebasePrincipal(ioService.newURI(principalURISpec), {});
  },

  getTriggeringPrincipal: function(aEvent)
  {
    let dataTransfer = aEvent.dataTransfer;
    return this._getTriggeringPrincipalFromDataTransfer(dataTransfer, true);

  },

  canDropLink: function(aEvent, aAllowSameDocument)
  {
    if (this._eventTargetIsDisabled(aEvent))
      return false;

    let dataTransfer = aEvent.dataTransfer;
    let types = dataTransfer.types;
    if (!types.includes("application/x-moz-file") &&
        !types.includes("text/x-moz-url") &&
        !types.includes("text/uri-list") &&
        !types.includes("text/x-moz-text-internal") &&
        !types.includes("text/plain"))
      return false;

    if (aAllowSameDocument)
      return true;

    let sourceNode = dataTransfer.mozSourceNode;
    if (!sourceNode)
      return true;

    // don't allow a drop of a node from the same document onto this one
    let sourceDocument = sourceNode.ownerDocument;
    let eventDocument = aEvent.originalTarget.ownerDocument;
    if (sourceDocument == eventDocument)
      return false;

    // also check for nodes in other child or sibling frames by checking
    // if both have the same top window.
    if (sourceDocument && eventDocument) {
      if (sourceDocument.defaultView == null)
        return true;
      let sourceRoot = sourceDocument.defaultView.top;
      if (sourceRoot && sourceRoot == eventDocument.defaultView.top)
        return false;
    }

    return true;
  },

  dropLink: function(aEvent, aName, aDisallowInherit)
  {
    aName.value = "";
    let links = this.dropLinks(aEvent, aDisallowInherit);
    let url = "";
    if (links.length > 0) {
      url = links[0].url;
      let name = links[0].name;
      if (name)
        aName.value = name;
    }

    return url;
  },

  dropLinks: function(aEvent, aDisallowInherit, aCount)
  {
    if (aEvent && this._eventTargetIsDisabled(aEvent))
      return [];

    let dataTransfer = aEvent.dataTransfer;
    let links = this._getDropLinks(dataTransfer);
    let triggeringPrincipal = this._getTriggeringPrincipalFromDataTransfer(dataTransfer, false);

    for (let link of links) {
      try {
        link.url = this._validateURI(dataTransfer, link.url, aDisallowInherit,
                                     triggeringPrincipal);
      } catch (ex) {
        // Prevent the drop entirely if any of the links are invalid even if
        // one of them is valid.
        aEvent.stopPropagation();
        aEvent.preventDefault();
        throw ex;
      }
    }
    if (aCount)
      aCount.value = links.length;

    return links;
  },

  validateURIsForDrop: function(aEvent, aURIsCount, aURIs, aDisallowInherit)
  {
    let dataTransfer = aEvent.dataTransfer;
    let triggeringPrincipal = this._getTriggeringPrincipalFromDataTransfer(dataTransfer, false);

    for (let uri of aURIs) {
      this._validateURI(dataTransfer, uri, aDisallowInherit,
                        triggeringPrincipal);
    }
  },

  queryLinks: function(aDataTransfer, aCount)
  {
    let links = this._getDropLinks(aDataTransfer);
    if (aCount) {
      aCount.value = links.length;
    }
    return links;
  },

  _eventTargetIsDisabled: function(aEvent)
  {
    let ownerDoc = aEvent.originalTarget.ownerDocument;
    if (!ownerDoc || !ownerDoc.defaultView)
      return false;

    return ownerDoc.defaultView
                   .QueryInterface(Ci.nsIInterfaceRequestor)
                   .getInterface(Ci.nsIDOMWindowUtils)
                   .isNodeDisabledForEvents(aEvent.originalTarget);
  }
};

var components = [ContentAreaDropListener];
this.NSGetFactory = XPCOMUtils.generateNSGetFactory(components);
