namespace com.keyman.dom {
  class SelectionCaret {
    node: Node;
    offset: number;

    constructor(node, offset) {
      this.node = node;
      this.offset = offset;
    }
  }

  class SelectionRange {
    start: SelectionCaret;
    end: SelectionCaret;

    constructor(start, end) {
      this.start = start;
      this.end = end;
    }
  }

  class StyleCommand {
    cmd: string;
    stateType: number;
    cache: string|boolean;

    constructor(c: string, s:number) {
      this.cmd = c;
      this.stateType = s;
    }
  }

  export class DesignIFrame extends text.OutputTarget {
    root: HTMLIFrameElement;
    doc: Document;
    docRoot: HTMLElement;

    commandCache: StyleCommand[];

    constructor(ele: HTMLIFrameElement) {
      super();
      this.root = ele;

      if(ele.contentWindow && ele.contentWindow.document && ele.contentWindow.document.designMode == 'on') {
        this.doc = ele.contentWindow.document;
        this.docRoot = ele.contentWindow.document.documentElement;
      } else {
        throw "Specified IFrame is not in design-mode!";
      }
    }

    getElement(): HTMLIFrameElement {
      return this.root;
    }

    hasSelection(): boolean {
      let Lsel = this.doc.getSelection();
      let outerSel = document.getSelection();

      // If the outer doc's selection matches, we're active.
      if(outerSel.anchorNode == Lsel.anchorNode && outerSel.focusNode == Lsel.focusNode) {
        return true;
      } else {
        // Problem:  for testing, we can't enforce the ideal (ie: first) condition.
        // Technically, the IFrame _will_ always have its own internal selection, though... so... it kinda works?
        return true;
      }
    }

    clearSelection(): void {
      if(this.hasSelection()) {
        let Lsel = this.doc.getSelection();

        if(!Lsel.isCollapsed) {
          Lsel.deleteFromDocument();  // I2134, I2192
        }
      } else {
        console.warn("Attempted to clear an unowned Selection!");
      }
    }

    invalidateSelection(): void { /* No cache maintenance needed here, partly because
                                   * it's impossible to cache a Selection; it mutates.
                                   */  }

    getCarets(): SelectionRange {
      let Lsel = this.doc.getSelection();
      let code = Lsel.anchorNode.compareDocumentPosition(Lsel.focusNode);

      if(Lsel.isCollapsed) {
        let caret = new SelectionCaret(Lsel.anchorNode, Lsel.anchorOffset);
        return new SelectionRange(caret, caret); 
      } else {
        let anchor = new SelectionCaret(Lsel.anchorNode, Lsel.anchorOffset);
        let focus = new SelectionCaret(Lsel.focusNode, Lsel.focusOffset);

        if(anchor.node == focus.node) {
          code = (focus.offset - anchor.offset > 0) ? 2 : 4;
        }

        if(code & 2) {
          return new SelectionRange(anchor, focus);
        } else { // Default
          // can test against code & 4 to ensure Focus is before anchor, though.
          return new SelectionRange(focus, anchor);
        }
      }
    }

    getDeadkeyCaret(): number {
      return this.getTextBeforeCaret().kmwLength();
    }

    getTextBeforeCaret(): string {
      if(!this.hasSelection()) {
        return;
      }

      let caret = this.getCarets().start;

      if(caret.node.nodeType != 3) {
        return ''; // Must be a text node to provide a context.
      }

      return caret.node.textContent.substr(0, caret.offset);
    }

    getTextAfterCaret(): string {
      if(!this.hasSelection()) {
        return;
      }

      let caret = this.getCarets().end;

      if(caret.node.nodeType != 3) {
        return ''; // Must be a text node to provide a context.
      }

      return caret.node.textContent.substr(caret.offset);
    }

    getText(): string {
      return this.docRoot.innerText;
    }

    deleteCharsBeforeCaret(dn: number) {
      if(!this.hasSelection() || dn <= 0) {
        return;
      }

      let start = this.getCarets().start;

      if(start.node.nodeType != 3) {
        console.warn("Deletion of characters requested without available context!");
        return; // No context to delete characters from.
      }

      let range = this.doc.createRange();
      let dnOffset = start.offset - start.node.nodeValue.substr(0, start.offset)._kmwSubstr(-dn).length;

      range.setStart(start.node, dnOffset);
      range.setEnd(start.node, start.offset);

      this.adjustDeadkeys(-dn);
      range.deleteContents();
      // No need to reposition the caret - the DOM will auto-move the selection accordingly, since
      // we didn't use the selection to delete anything.
    }

    insertTextBeforeCaret(s: string) {
      if(!this.hasSelection()) {
        return;
      }

      let start = this.getCarets().start;
      let delta = s._kmwLength();
      let Lsel = this.doc.getSelection();

      if(delta == 0) {
        return;
      }

      this.adjustDeadkeys(delta);

      // While Selection.extend() is really nice for this, IE doesn't support it whatsoever.
      // However, IE (11, at least) DOES support setting selections via ranges, so we can still
      // manage the caret properly.
      let finalCaret = this.root.ownerDocument.createRange();

      if(start.node.nodeType == 3) {
        let textStart = <Text> start.node;
        textStart.insertData(start.offset, s);
        finalCaret.setStart(textStart, start.offset + s.length);
      } else {
        // Create a new text node - empty control
        var n = this.doc.createTextNode(s);

        let range = this.doc.createRange();
        range.setStart(start.node, start.offset);
        range.collapse(true);
        range.insertNode(n);
      }

      finalCaret.collapse(true);
      Lsel.removeAllRanges();
      try {
        Lsel.addRange(finalCaret);
      } catch(e) {
        // Chrome (through 4.0 at least) throws an exception because it has not synchronised its content with the selection.
        // scrollIntoView synchronises the content for selection
        start.node.parentElement.scrollIntoView();
        Lsel.addRange(finalCaret);
      }
      Lsel.collapseToEnd();
    }

    protected setTextAfterCaret(s: string) {
      if(!this.hasSelection()) {
        return;
      }

      let caret = this.getCarets().end;
      let delta = s._kmwLength();
      let Lsel = this.doc.getSelection();

      if(delta == 0) {
        return;
      }

      // This is designed explicitly for use in direct-setting operations; deadkeys
      // will be handled after this method.

      if(caret.node.nodeType == 3) {
        let textStart = <Text> caret.node;
        textStart.replaceData(caret.offset, textStart.length, s);
      } else {
        // Create a new text node - empty control
        var n = caret.node.ownerDocument.createTextNode(s);

        let range = this.root.ownerDocument.createRange();
        range.setStart(caret.node, caret.offset);
        range.collapse(true);
        range.insertNode(n);
      }
    }

    /**
     * Function     saveProperties
     * Scope        Private
     * Description  Build and create list of styles that can be applied in iframes
     */
    saveProperties() {
      // Formerly _CacheCommands.
      var _CacheableCommands=[
        new StyleCommand('backcolor',1), new StyleCommand('fontname',1), new StyleCommand('fontsize',1), 
        new StyleCommand('forecolor',1), new StyleCommand('bold',0), new StyleCommand('italic',0), 
        new StyleCommand('strikethrough',0), new StyleCommand('subscript',0),
        new StyleCommand('superscript',0), new StyleCommand('underline',0)
      ];

      if(this.doc.defaultView) {
        _CacheableCommands.push(new StyleCommand('hilitecolor',1));
      }
        
      for(var n=0; n < _CacheableCommands.length; n++) { // I1511 - array prototype extended
        let cmd = _CacheableCommands[n];
        //KeymanWeb._Debug('Command:'+_CacheableCommands[n][0]);
        if(cmd.stateType == 1) {
          cmd.cache = this.doc.queryCommandValue(cmd.cmd);
        } else {
          cmd.cache = this.doc.queryCommandState(cmd.cmd);
        }
      }
      this.commandCache = _CacheableCommands;
    }

    /**
     * Function     restoreProperties
     * Scope        Private
     * Description  Restore styles in IFRAMEs (??)
     */
    restoreProperties(_func?: () => void): void {
      // Formerly _CacheCommandsReset.
      if(!this.commandCache) {
        console.error("No command cache exists to restore!");
      }

      for(var n=0; n < this.commandCache.length; n++) { // I1511 - array prototype extended
        let cmd = this.commandCache[n];

        //KeymanWeb._Debug('ResetCacheCommand:'+_CacheableCommands[n][0]+'='+_CacheableCommands[n][2]);
        if(cmd.stateType == 1) {
          if(this.doc.queryCommandValue(cmd.cmd) != cmd.cache) {
            if(_func) {
              _func();
            }
            this.doc.execCommand(cmd.cmd, false, <string> cmd.cache);
          }
        } else if(this.doc.queryCommandState(cmd.cmd) != cmd.cache) {
          if(_func) {
            _func();
          }
          //KeymanWeb._Debug('executing command '+_CacheableCommand[n][0]);
          this.doc.execCommand(cmd.cmd, false, null);
        }
      }
    }
  }
}