** locally-edited content.  frid is the RID of the file's blob entry
** from which pContent is based. zManifestUuid is the checkin version
** to which RID belongs - it is purely informational, for labeling the
** diff view. isSbs is true for side-by-side diffs, false for unified.
*/
static void fileedit_render_diff(Blob * pContent, int frid,
                                 const char * zManifestUuid,
                                 int isSbs){
                                 u64 diffFlags){
  Blob orig = empty_blob;
  Blob out = empty_blob;
  u64 diffFlags = DIFF_HTML | DIFF_NOTTOOBIG | DIFF_STRIP_EOLCR

    | (isSbs ? DIFF_SIDEBYSIDE : DIFF_LINENO);
  content_get(frid, &orig);
  text_diff(&orig, pContent, &out, 0, diffFlags);
  if(isSbs || blob_size(&out)==0){
  if(blob_size(&out)==0){
    /* nothing to do */
  }else if(DIFF_SIDEBYSIDE & diffFlags){
    CX("%b",&out);
  }else{
    CX("<pre class='udiff'>%b</pre>",&out);
  }
  blob_reset(&orig);
  blob_reset(&out);
}

** filename=FILENAME
** content=text
** checkin=checkin version
**
** Optional parameters:
**
** sbs=integer (1=side-by-side or 0=unified, default=0)
**
** ws=integer (0=diff whitespace, 1=ignore EOL ws, 2=ignore all ws)
**
** Reminder to self: search info.c for isPatch to see how a
** patch-style siff can be produced.
**
** User must have Write access to use this page.
**
** Responds with the HTML content of the diff. On error it produces a
** JSON response as documented for fileedit_ajax_error().
*/
static void fileedit_ajax_diff(void){
  /*
  ** Reminder: we only need the filename to perform valdiation
  ** against fileedit_is_editable(), else this route could be
  ** abused to get diffs against content disallowed by the
  ** whitelist.
  */
  const char * zFilename = 0;
  const char * zRev = 0;
  const char * zContent = P("content");
  char * zRevUuid = 0;
  int isSbs = atoi(PD("sbs","0"));
  int vid, frid;
  int vid, frid, iFlag;
  u64 diffFlags = DIFF_HTML | DIFF_NOTTOOBIG;
  Blob content = empty_blob;

  iFlag = atoi(PD("sbs","0"));
  if(0==iFlag){
    diffFlags |= DIFF_LINENO;
  }else{
    diffFlags |= DIFF_SIDEBYSIDE;
  }
  iFlag = atoi(PD("ws","2"));
  if(2==iFlag){
    diffFlags |= DIFF_IGNORE_ALLWS;
  }else if(1==iFlag){
    diffFlags |= DIFF_IGNORE_EOLWS;
  }
  diffFlags |= DIFF_STRIP_EOLCR;
  fileedit_get_fnci_args( &zFilename, &zRev );
  if(!fileedit_ajax_boostrap()
     || !fileedit_ajax_setup_filerev(zRev, &zRevUuid, &vid,
                                     zFilename, &frid)){
    return;
  }
  if(!zContent){
    zContent = "";
  }
  cgi_set_content_type("text/html");
  blob_init(&content, zContent, -1);
  fileedit_render_diff(&content, frid, zRevUuid, isSbs);
  fileedit_render_diff(&content, frid, zRevUuid, diffFlags);
  fossil_free(zRevUuid);
  blob_reset(&content);
}

/*
** Sets up and validates most, but not all, of p's checkin-related
** state from the CGI environment. Returns 0 on success or a suggested

  {
    CX("<div id='fileedit-tab-diff' "
       "data-tab-parent='fileedit-tabs' "
       "data-tab-label='Diff'"
       ">");

    CX("<div class='fileedit-options flex-container flex-row' "
       "id='fileedit-tab-diff-buttons'>"
       "<button class='sbs'>Side-by-side</button>"
       "<button class='unified'>Unified</button>"
       "</div>");
       "id='fileedit-tab-diff-buttons'>");
    CX("<button class='sbs'>Side-by-side</button>"
       "<button class='unified'>Unified</button>");
    if(0){
      /* For the time being let's just ignore all whitespace
      ** changes, as files with Windows-style EOLs always show
      ** more diffs than we want then they're submitted to
      ** ?ajax=diff because JS normalizes them to Unix EOLs.
      ** We can revisit this decision later. */
      style_select_list_int("diff-ws-policy",
                            "diff_ws", "Whitespace",
                            "Whitespace handling policy.",
                            2,
                            "Diff all whitespace", 0,
                            "Ignore EOL whitespace", 1,
                            "Ignore all whitespace", 2,
                            NULL);
    }
    CX("</div>");
    CX("<div id='fileedit-tab-diff-wrapper'>"
       "Diffs will be shown here."
       "</div>");
    CX("</div>"/*#fileedit-tab-diff*/);
  }

  /****** Commit ******/