@IBAction func startSearch(sender: AnyObject) {
        let searchTerm: String = searchBox.stringValue
        if (searchTerm.isEmpty) {
            endSearch(self)
            return
        }

        // the user can move forward to the next match by hitting enter/return
        if (canMoveToMatch(true)) {
            moveToMatch()
            return
        }

        let doc: PDFDocument = model!.doc!
        found = doc.findString(searchTerm, withOptions: getSearchOption())
        searchMode = true
        searchResultsInfoBox.hidden = false
        searchResultsCount.stringValue = "Found \(found.count) matches"
        moveToMatch()
    }

    func getSearchOption() -> Int {
        if (backwardSearchOption.state == NSOnState) {
            println("searching backwards")
            return backwardSearch
        }
        println("searching normally")
        return caseInsensitiveSearch
    }

    @IBAction func navigateSearchResults(sender: AnyObject) {
        let selected: Int = sender.selectedSegment
        let back: Bool = backwardSearchOption.state == NSOnState

        if (selected == 0) {
            if (canMoveToMatch(back)) {
                moveToMatch()
            }
        } else {
            if (canMoveToMatch(!back)) {
                moveToMatch()
            }
        }
    }

    func canMoveToMatch(next: Bool) -> Bool {
        if (searchMode) {
            if (next) {
                if (matchNum >= 0 && matchNum < (found.count - 1)) {
                    matchNum++
                    return true
                }
            } else {
                if (matchNum > 0 && matchNum <= found.count) {
                    matchNum--
                    return true
                }
            }
        }
        return false
    }

    func moveToMatch() {
        // highlight the occurrence of the search term
        documentView.setCurrentSelection(found[matchNum] as! PDFSelection)
        // scroll to the highlighted occurrence
        documentView.scrollSelectionToVisible(self)
    }

    @IBAction func endSearch(sender: AnyObject) {
        let doc: PDFDocument = model!.doc!
        documentView.setCurrentSelection(nil)
        searchResultsInfoBox.hidden = true
        searchBox.stringValue = ""
        if (backwardSearchOption.state == NSOnState) {
            backwardSearchOption.state = NSOffState
        }
        window?.makeFirstResponder(nil)
        found.removeAll()
        matchNum = 0
        searchMode = false
    }