(function(F/*the fossil object*/){
  "use strict";
  /**
     Code for the /filepage app. Requires that the fossil JS
     bootstrapping is complete and fossil.fetch() has been installed.

     Custom events, handled via fossil.page.addEventListener():

     - Event 'fileedit-file-loaded': passes on information when it
     loads a file, in the form of an object:

     {
     filename: string,
     checkin: UUID string,
     isExe: bool,
     mimetype: mimetype stringas determined by the fossil server.
     }

     The fossil.page.value() method gets or sets the current file
     content for the page. Hypothetically, this can be overridden by
     skin-level JS in order to use a custom 3rd-party editing widget
     in place of the built-in textarea, but that is as yet untested.
     In order to do so the client would need to replace DOM element
     #fileedit-content-editor with their custom widget.

     - Event 'fileedit-preview-updated': when the preview is refreshed
     from the server, this event passes on information about the preview
     change in the form of an object:

     {
     element: the DOM element which contains the content preview.

     mimetype: the fossil-reported content mimetype.

     previewMode: a string describing the preview mode: see
       the fossil.page.previewModes map for the values. This can
       be used to determine whether, e.g., the content is suitable
       for applying a 3rd-party code highlighting API to.
     }

     Here's an example which can be used with the highlightjs code
     highlighter to update the highlighting when the preview is
     refreshed in "wiki" mode (which includes fossil-native wiki and
     markdown):

     fossil.page.addEventListener(
       'fileedit-preview-updated',
       (ev)=>{
         if(ev.detail.previewMode==='wiki'){
           ev.detail.element.querySelectorAll(
             'code[class^=language-]'
           ).forEach((e)=>hljs.highlightBlock(e));
         }
       }
     );
  */
  const E = (s)=>document.querySelector(s),
        D = F.dom,
        P = F.page;

  /**
     Widget for the checkin/file selection list.
  */
  P.fileSelector = {
    e:{
      container: E('#fileedit-file-selector')
    },
    finfo: {},
    cache: {
      checkins: undefined,
      files:{}
    },
    /**
       Fetches the list of leaf checkins from the server and updates
       the UI with that list.
    */
    loadLeaves: function(){
      D.append(D.clearElement(
        this.e.ciListLabel,
        this.e.selectCi,
        this.e.selectFiles
      ),"Loading leaves...");
      D.disable(this.e.btnLoadFile, this.e.selectFiles, this.e.selectCi); 
      const self = this;
      F.fetch('fileedit',{
        urlParams:'ajax=filelist&leaves',
        responseType: 'json',
        onload: function(list){
          D.append(D.clearElement(self.e.ciListLabel),
                   "Open leaves (newest first):");
          self.cache.checkins = list;
          D.clearElement(D.enable(self.e.selectCi));
          let loadThisOne;
          list.forEach(function(o,n){
            if(!n) loadThisOne = o;
            D.option(self.e.selectCi, o.checkin,
                     o.timestamp+' ['+o.branch+']: '
                     +F.hashDigits(o.checkin));
          });
          self.loadFiles(loadThisOne ? loadThisOne.checkin : false);
        }
      });
    },
    /**
       Loads the file list for the given checkin UUID. It uses a
       cached copy on subsequent calls for the same UUID. If passed a
       falsy value, it instead clears and disables the file selection
       list.
    */
    loadFiles: function(ciUuid){
      delete this.finfo.filename;
      this.finfo.checkin = ciUuid;
      const selFiles = this.e.selectFiles;
      if(!ciUuid){
        D.clearElement(D.disable(selFiles, this.e.btnLoadFile));
        return this;
      }
      const onload = (response)=>{
        D.clearElement(selFiles, this.e.btnLoadFile);
        D.append(
          D.clearElement(this.e.fileListLabel),
          "Editable files for ",
          D.append(
            D.code(),
            D.a(F.repoUrl('timeline',{
              c: ciUuid
            }), F.hashDigits(ciUuid)),
          ),
          ":"
        );
        this.cache.files[response.checkin] = response;
        response.editableFiles.forEach(function(fn,n){
          D.option(selFiles, fn);
        });
        if(selFiles.options.length){
          D.enable(selFiles, this.e.btnLoadFile);
        }
      };
      const got = this.cache.files[ciUuid];
      if(got){
        onload(got);
        return this;
      }
      D.disable(selFiles,this.e.btnLoadFile);
      D.clearElement(selFiles);
      D.append(D.clearElement(this.e.fileListLabel),
               "Loading files for "+F.hashDigits(ciUuid)+"...");
      F.fetch('fileedit',{
        urlParams:{ajax:'filelist', checkin: ciUuid},
        responseType: 'json',
        onload
      });
      return this;
    },
    /**
       Initializes the checkin/file selector widget. Must only be
       called once.
    */
    init: function(){
      const selCi = this.e.selectCi = D.select(),
            selFiles = this.e.selectFiles
            = D.addClass(D.select(), 'file-list'),
            btnLoad = this.e.btnLoadFile =
            D.addClass(D.button("Load file"), "flex-shrink"),
            filesLabel = this.e.fileListLabel =
            D.addClass(D.div(),'flex-shrink','file-list-label'),
            ciLabelWrapper = D.addClass(
              D.div(), 'flex-container','flex-row', 'flex-shrink',
              'stretch'
            ),
            btnReload = D.addClass(
              D.button('Reload'), 'flex-shrink'
            ),
            ciLabel = this.e.ciListLabel =
            D.addClass(D.span(),'flex-shrink','checkin-list-label')
      ;
      D.attr(selCi, 'title',"The list of opened leaves.");
      D.attr(selFiles, 'title',
             "The list of editable files for the selected checkin.");
      D.attr(btnLoad, 'title',
             "Load the selected file into the editor.");
      D.disable(selCi, selFiles, btnLoad);
      D.attr(selFiles, 'size', 10);
      D.append(
        this.e.container,
        D.append(ciLabelWrapper,
                 btnReload, ciLabel),
        selCi,
        filesLabel,
        selFiles,
        btnLoad
      );
      this.loadLeaves();
      selCi.addEventListener(
        'change', (e)=>this.loadFiles(e.target.value), false
      );
      btnLoad.addEventListener(
        'click', (e)=>{
          this.finfo.filename = selFiles.value;
          if(this.finfo.filename){
            P.loadFile(this.finfo.filename, this.finfo.checkin);
          }
        }, false
      );
      btnReload.addEventListener(
        'click', (e)=>this.loadLeaves(), false
      );
      delete this.init;
    }
  }/*P.fileSelector*/;

  /**
     Internal workaround to select the current preview mode
     and fire a change event if the value actually changes
     or if forceEvent is truthy.
  */
  P.selectPreviewMode = function(modeValue, forceEvent){
    const s = this.e.selectPreviewMode;
    if(!modeValue) modeValue = s.value;
    else if(s.value != modeValue){
      s.value = modeValue;
      forceEvent = true;
    }
    if(forceEvent){
      // Force UI update
      s.dispatchEvent(new Event('change',{target:s}));
    }
  };

  window.addEventListener("load", function() {
    P.base = {tag: E('base')};
    P.base.originalHref = P.base.tag.href;
    P.tabs = new fossil.TabManager('#fileedit-tabs');
    P.e = {
      taEditor: E('#fileedit-content-editor'),
      taCommentSmall: E('#fileedit-comment'),
      taCommentBig: E('#fileedit-comment-big'),
      ajaxContentTarget: E('#ajax-target'),
      btnCommit: E("#fileedit-btn-commit"),
      btnReload: E("#fileedit-tab-content > .fileedit-options > "
                   +"button.fileedit-content-reload"),
      selectPreviewMode: E('#select-preview-mode select'),
      selectHtmlEmsWrap: E('#select-preview-html-ems'),
      selectEolWrap:  E('#select-preview-html-ems'),
      selectFontSizeWrap: E('#select-font-size'),
      cbLineNumbersWrap: E('#cb-line-numbers'),
      cbAutoPreview: E('#cb-preview-autoupdate > input[type=checkbox]'),
      previewTarget: E('#fileedit-tab-preview-wrapper'),
      cbIsExe: E('input[type=checkbox][name=exec_bit]'),
      fsFileVersionDetails: E('#file-version-details'),
      tabs:{
        content: E('#fileedit-tab-content'),
        preview: E('#fileedit-tab-preview'),
        diff: E('#fileedit-tab-diff'),
        commit: E('#fileedit-tab-commit')
      }
    };
    P.fileSelector.init();
    /* Figure out which comment editor to show by default and
       hide the other one. By default we take the one which does
       not have the 'hidden' CSS class. If neither do, we default
       to single-line mode. */
    if(D.hasClass(P.e.taCommentSmall, 'hidden')){
      P.e.taComment = P.e.taCommentBig;
    }else if(D.hasClass(P.e.taCommentBig,'hidden')){
      P.e.taComment = P.e.taCommentSmall;
    }else{
      P.e.taComment = P.e.taCommentSmall;
      D.addClass(P.e.taCommentBig, 'hidden');
    }
    D.removeClass(P.e.taComment, 'hidden');

    P.tabs.e.container.insertBefore(
      /* Move the status bar between the tab buttons and
         tab panels. Seems to be the best fit in terms of
         functionality and visibility. */
      E('#fossil-status-bar'), P.tabs.e.tabs
    );

    P.tabs.addEventListener(
      /* Set up auto-refresh of the preview tab... */
      'before-switch-to', function(ev){
        if(ev.detail===P.e.tabs.preview){
          P.baseHrefForFile();
          if(P.e.cbAutoPreview.checked) P.preview();
        }
      }
    );
    P.tabs.addEventListener(
      /* Set up auto-refresh of the preview tab... */
      'before-switch-from', function(ev){
        if(ev.detail===P.e.tabs.preview){
          P.baseHrefRestore();
        }
      }
    );

    F.connectPagePreviewers(
      P.e.tabs.preview.querySelector(
        '#btn-preview-refresh'
      )
    );

    const diffButtons = E('#fileedit-tab-diff-buttons');
    diffButtons.querySelector('button.sbs').addEventListener(
      "click",(e)=>P.diff(true), false
    );
    diffButtons.querySelector('button.unified').addEventListener(
      "click",(e)=>P.diff(false), false
    );
    P.e.btnCommit.addEventListener(
      "click",(e)=>P.commit(), false
    );
    F.confirmer(P.e.btnReload, {
      confirmText: "Really reload, losing edits?",
      onconfirm: (e)=>P.loadFile(),
      ticks: 3
    });
    E('#comment-toggle').addEventListener(
      "click",(e)=>P.toggleCommentMode(), false
    );

    /**
       Cosmetic: jump through some hoops to enable/disable
       certain preview options depending on the current
       preview mode...
    */
    P.e.selectPreviewMode.addEventListener(
      "change", function(e){
        const mode = e.target.value,
              name = P.previewModes[mode],
              hide = [], unhide = [];
        P.previewModes.current = name;
        if('guess'===name){
          unhide.push(P.e.cbLineNumbersWrap,
                      P.e.selectHtmlEmsWrap);
        }else{
          if('text'===name) unhide.push(P.e.cbLineNumbersWrap);
          else hide.push(P.e.cbLineNumbersWrap);
          if('htmlIframe'===name) unhide.push(P.e.selectHtmlEmsWrap);
          else hide.push(P.e.selectHtmlEmsWrap);
        }
        hide.forEach((e)=>e.classList.add('hidden'));
        unhide.forEach((e)=>e.classList.remove('hidden'));
      }, false
    );
    P.selectPreviewMode(false, true);
    const selectFontSize = E('select[name=editor_font_size]');
    if(selectFontSize){
      selectFontSize.addEventListener(
        "change",function(e){
          const ed = P.e.taEditor;
          ed.className = ed.className.replace(
              /\bfont-size-\d+/g, '' );
          ed.classList.add('font-size-'+e.target.value);
        }, false
      );
      selectFontSize.dispatchEvent(
        // Force UI update
        new Event('change',{target:selectFontSize})
      );
    }

    if(0){ // only for testing
      P.addEventListener(
        'fileedit-file-loaded',
        (e)=>console.debug('fileedit-file-loaded ==>',e)
      );
    }

  }, false)/*onload event handler*/;

  /**
     Getter (if called with no args) or setter (if passed an arg) for
     the current file content. We use a function, rather than direct
     access, so that clients can hypothetically swap out this method
     from their skin in order to facilitate plugging-in of a fancy
     3rd-party editor widget.

     The setter form returns this object, and re-implementations must
     do the same.
  */
  P.value = function(){
    if(0===arguments.length){
      return this.e.taEditor.value;
    }else{
      this.e.taEditor.value = arguments[0];
      return this;
    }
  };

  /**
     If either of...

     - P.previewModes.current==='wiki'

     - P.previewModes.current==='guess' AND the currently-loaded file
     has a mimetype of "text/x-fossil-wiki" or "text/x-markdown".

     ... then this function updates the document's base.href to a
     repo-relative /doc/{{this.finfo.checkin}}/{{directory part of
     this.finfo.filename}}/

     If neither of those conditions applies, this is a no-op.
  */
  P.baseHrefForFile = function f(){
    const fn = this.finfo ? this.finfo.filename : undefined;
    if(!fn) return this;
    if(!f.wikiMimeTypes){
      f.wikiMimeTypes = ["text/x-fossil-wiki", "text/x-markdown"];
    }
    if('wiki'===P.previewModes.current
       || ('guess'===P.previewModes.current
           && f.wikiMimeTypes.indexOf(this.finfo.mimetype)>=0)){
      const a = fn.split('/');
      a.pop();
      this.base.tag.href = F.repoUrl(
        'doc/'+F.hashDigits(this.finfo.checkin)
          +'/'+(a.length ? a.join('/')+'/' : '')
      );
    }
    return this;
  };

  /**
     Sets the document's base.href value to its page-load-time
     setting.
  */
  P.baseHrefRestore = function(){
    P.base.tag.href = P.base.originalHref;
  };

  /**
     Toggles between single- and multi-line comment
     mode.
  */
  P.toggleCommentMode = function(){
    var s, h, c = this.e.taComment.value;
    if(this.e.taComment === this.e.taCommentSmall){
      s = this.e.taCommentBig;
      h = this.e.taCommentSmall;
    }else{
      s = this.e.taCommentSmall;
      h = this.e.taCommentBig;
      /*
        Doing (input[type=text].value = textarea.value) unfortunately
        strips all newlines. To compensate we'll replace each EOL with
        a space. Not ideal. If we were to instead escape them as \n,
        and do the reverse when toggling again, then they would get
        committed as escaped newlines if the user did not first switch
        back to multi-line mode. We cannot blindly unescape the
        newlines, in the off chance that the user actually enters \n
        in the comment.
      */
      c = c.replace(/\r?\n/g,' ');
    }
    s.value = c;
    this.e.taComment = s;
    D.addClass(h, 'hidden');
    D.removeClass(s, 'hidden');
    console.debug(s,h);
  };

  /**
     Returns true if fossil.page.finfo is set, indicating that a file
     has been loaded, else it reports an error and returns false.
  */
  const affirmHasFile = function(){
    if(!P.finfo) F.error("No file is loaded.");
    return !!P.finfo;
  };
  
  /**
     updateVersion() updates the filename and version in various UI
     elements...

     Returns this object.
  */
  P.updateVersion = function(file,rev){
    if(1===arguments.length){/*assume object*/
      this.finfo = arguments[0];
      file = this.finfo.filename;
      rev = this.finfo.checkin;
    }else if(0===arguments.length){
      if(!affirmHasFile()) return this;
    }else{
      this.finfo = {filename:file,checkin:rev};
    }
    const eTgt = this.e.fsFileVersionDetails.querySelector('div'),
          rHuman = F.hashDigits(rev),
          rUrl = F.hashDigits(rev,true);
    D.clearElement(eTgt);
    D.append(
      eTgt, "File: ",
      D.append(D.code(),
               D.a(F.repoUrl('finfo',{name:file, m:rUrl}), file)),
      D.br()
    );
    D.append(
      eTgt, "Checkin Version: ",
      D.append(D.code(), D.a(F.repoUrl('info/'+rUrl), rHuman)),
      " [",D.a(F.repoUrl('timeline',{m:rUrl}), "timeline"),"]",
      D.br()
    );
    D.append(
      eTgt, "Mimetype: ",
      D.append(D.code(), this.finfo.mimetype||'???'),
      D.br()
    );
    const purlArgs = F.encodeUrlArgs({
      filename: this.finfo.filename,
      checkin: rUrl
    },false,true);
    const purl = F.repoUrl('fileedit',purlArgs);
    D.append(
      eTgt,"[",D.a(purl,"Editor permalink"),"]"
    );
    return this;
  };

  /**
     Removes the default editor widget (and any dependent elements)
     from the DOM, adds the given element in its place, removes this
     method from this object, and returns this object.
  */
  P.replaceEditorElement = function(newEditor){
    P.e.taEditor.parentNode.insertBefore(
      newEditor,
      P.e.taEditor
    );
    P.e.taEditor.remove();
    P.e.selectFontSizeWrap.remove();
    delete this.replaceEditorElement;
    return P;
  };

  /**
     loadFile() loads (file,checkinVersion) and updates the relevant
     UI elements to reflect the loaded state. If passed no arguments
     then it re-uses the values from the currently-loaded file, reloading
     it (emitting an error message if no file is loaded).

     Returns this object, noting that the load is async. After loading
     it triggers a 'fileedit-file-loaded' event, passing it
     this.finfo.
  */
  P.loadFile = function(file,rev){
    if(0===arguments.length){
      if(!affirmHasFile()) return this;
      file = this.finfo.filename;
      rev = this.finfo.checkin;
    }
    delete this.finfo;
    const self = this;
    F.message("Loading content...");
    F.fetch('fileedit',{
      urlParams: {
        ajax: 'content',
        filename:file,
        checkin:rev
      },
      responseHeaders: ['x-fileedit-file-perm', 'content-type'],
      onload:(r,headers)=>{
        F.message('Loaded content.');
        self.updateVersion({
          filename: file,
          checkin: rev,
          isExe: ('x'===headers['x-fileedit-file-perm']),
          mimetype: headers['content-type'].split(';').shift()
        });
        self.tabs.switchToTab(self.e.tabs.content);
        self.e.cbIsExe.checked = self.finfo.isExe;
        self.value(r);
        self.dispatchEvent('fileedit-file-loaded', self.finfo);
      }
    });
    return this;
  };

  /**
     Fetches the page preview based on the contents and settings of
     this page's input fields, and updates the UI with with the
     preview.

     Returns this object, noting that the operation is async.
  */
  P.preview = function f(switchToTab){
    if(!affirmHasFile()) return this;
    const target = this.e.previewTarget,
          self = this;
    const updateView = function(c){
      D.clearElement(target);
      if('string'===typeof c) target.innerHTML = c;
      if(switchToTab) self.tabs.switchToTab(self.e.tabs.preview);
    };
    return this._postPreview(this.value(), updateView);
  };

  /**
     Callback for use with F.connectPagePreviewers()
  */
  P._postPreview = function(content,callback){
    if(!affirmHasFile()) return this;
    if(!content){
      callback(content);
      return this;
    }
    const fd = new FormData();
    fd.append('render_mode',this.e.selectPreviewMode.value);
    fd.append('filename',this.finfo.filename);
    fd.append('ln',E('[name=preview_ln]').checked ? 1 : 0);
    fd.append('iframe_height', E('[name=preview_html_ems]').value);
    fd.append('content',content || '');
    F.message(
      "Fetching preview..."
    ).fetch('fileedit',{
      urlParams: {ajax: 'preview'},
      payload: fd,
      responseHeaders: 'x-fileedit-render-mode',
      onload: (r,header)=>{
        P.selectPreviewMode(P.previewModes[header]);
        if('wiki'===header) P.baseHrefForFile();
        else P.baseHrefRestore();
        callback(r);
        F.message('Updated preview.');
        P.dispatchEvent('fileedit-preview-updated',{
          previewMode: P.previewModes.current,
          mimetype: P.finfo.mimetype,
          element: P.e.previewTarget
        });
      },
      onerror: (e)=>{
        fossil.fetch.onerror(e);
        callback("Error fetching preview: "+e);
      }
    });
    return this;
  };

  /**
     Fetches the content diff based on the contents and settings of
     this page's input fields, and updates the UI with the diff view.

     Returns this object, noting that the operation is async.
  */
  P.diff = function f(sbs){
    if(!affirmHasFile()) return this;
    const content = this.value(),
          self = this;
    if(!f.target){
      f.target = this.e.tabs.diff.querySelector(
        '#fileedit-tab-diff-wrapper'
      );
    }
    const fd = new FormData();
    fd.append('filename',this.finfo.filename);
    fd.append('checkin', this.finfo.checkin);
    fd.append('sbs', sbs ? 1 : 0);
    fd.append('content',content);
    F.message(
      "Fetching diff..."
    ).fetch('fileedit',{
      urlParams: {ajax: 'diff'},
      payload: fd,
      onload: function(c){
        f.target.innerHTML = [
          "<div>Diff <code>[",
          self.finfo.checkin,
          "]</code> &rarr; Local Edits</div>",
          c||'No changes.'
        ].join('');
        F.message('Updated diff.');
        self.tabs.switchToTab(self.e.tabs.diff);
      }
    });
    return this;
  };

  /**
     Performs an async commit based on the form contents and updates
     the UI.

     Returns this object.
  */
  P.commit = function f(){
    if(!affirmHasFile()) return this;
    const self = this;
    const content = this.value(),
          target = document.querySelector('#fileedit-manifest'),
          cbDryRun = E('[name=dry_run]'),
          isDryRun = cbDryRun.checked,
          filename = this.finfo.filename;
    if(!f.updateView){
      f.updateView = function(c){
        target.innerHTML = [
          "<h3>Manifest",
          (c.dryRun?" (dry run)":""),
          ": ", F.hashDigits(c.uuid),"</h3>",
          "<code class='fileedit-manifest'>",
          c.manifest,
          "</code></pre>"
        ].join('');
        const msg = [
          'Committed',
          c.dryRun ? '(dry run)' : '',
          '[', F.hashDigits(c.uuid) ,'].'
        ];
        if(!c.dryRun){
          msg.push('Re-activating dry-run mode.');
          self.e.taComment.value = '';
          cbDryRun.checked = true;
          self.finfo.filename = filename;
          self.finfo.checkin = c.uuid;
          self.updateVersion();
          self.fileSelector.loadLeaves();
        }
        F.message.apply(F, msg);
        self.tabs.switchToTab(self.e.tabs.commit);
      };
    }
    if(!content){
      f.updateView('');
      return this;
    }
    const fd = new FormData();
    fd.append('filename',filename);
    fd.append('checkin', this.finfo.checkin);
    fd.append('content',content);
    fd.append('dry_run',isDryRun ? 1 : 0);
    /* Text fields or select lists... */
    ['comment_mimetype',
     'comment'
    ].forEach(function(name){
      var e = E('[name='+name+']');
      if(e) fd.append(name,e.value);
    });
    /* Checkboxes: */
    ['allow_fork',
     'allow_older',
     'exec_bit',
     'allow_merge_conflict',
     'prefer_delta'
    ].forEach(function(name){
      var e = E('[name='+name+']');
      if(e){
        if(e.checked) fd.append(name, 1);
      }else{
        console.error("Missing checkbox? name =",name);
      }
    });
    F.message(
      "Checking in..."
    ).fetch('fileedit',{
      urlParams: {ajax: 'commit'},
      payload: fd,
      responseType: 'json',
      onload: f.updateView
    });
    return this;
  };
  
})(window.fossil);
