MixModeler:

pkgs = c("rhandsontable", "shiny", "bs4Dash")
for (pkg in pkgs){
    library(pkg, character.only = T)
}

source("global.R", local = TRUE)

ui = bs4DashPage(
    navbar = bs4DashNavbar(
        tags$div(h1(
            class = "navbar-brand my-auto",
            "Mix Modeler"
        )),
        rightUi = tagList(
            tags$ul(
                class = "navbar-nav mr-auto",
                tags$li(
                    class = "nav-item activate px-2 my-auto",
                    tags$a(
                        calss = "nav-link",
                        href = "http://www.chenghaozhu.net",
                        tags$i(
                            class = "fas fa-home fa-2x text-dark"
                        )
                    )
                ),
                tags$li(
                    class = "nav-item activate px-2 my-auto",
                    tags$a(
                        calss = "nav-link",
                        href = "http://www.github.com/zhuchcn/MixModeler",
                        tags$i(
                            class = "fab fa-github fa-2x text-dark"
                        )
                    )
                )
            )
        )
    ),
    sidebar = bs4DashSidebar(

    ),
    body = bs4DashBody(
        tags$head(
            tags$link(rel = "stylesheet", type = "text/css", href="styles.css")
        ),
        shinyjs::useShinyjs(),
        shinyjs::extendShinyjs(text = jsCode),
        fluidRow(
            class = "pt-2",
            tags$div(
                class = "col-lg-3 col-md-4 col-sm-5",
                bs4Card(
                    width = 12,
                    height = "auto",
                    tags$div(
                        class = "my-control-panel",
                        numericInput("nrow", "Number of Rows",
                                     min = 1, max = 1000, step = 1, value = 1, width = "100%"),
                        numericInput("ncol", "Number of Columns",
                                     min = 1, max = 1000, step = 1, value = 1, width = "100%"),
                        actionButton("init", "Initialize it", class="btn-outline-primary btn-block pb-2"),
                        actionButton("data_submit_btn", "Submit It", class="btn-primary btn-block pb-2"),
                        actionButton("coltype_btn", "Column Types", class="btn-outline-primary btn-block pb-2"),
                        actionButton("colnames_btn", "Column Names", class="btn-outline-primary btn-block pb-2"),
                        tags$hr(),
                        textInput("formula", "Formula",
                                  placeholder = "value ~ var1 + var2", width = "100%"),
                        actionButton("test", "Test it", class="btn-danger btn-block pb-2"),
                        tags$hr(),
                        actionButton("showHelp", "Help", class="btn-info btn-block pb-2")
                    )
                )
            ),
            tags$div(
                class = "col-lg-9 col-md-8 col-sm-7",
                tags$div(
                    id = "my-data-table",
                    bs4Card(
                        width = 12,
                        rHandsontableOutput("dataTable")
                    )
                ),
                tags$div(
                    id = "help-page",
                    bs4Card(
                        status = "info",
                        width = 12,
                        title = "Instructions",
                        tags$ul(
                            calss = "list-group list-group-flush",
                            tags$li(
                                class = "list-group-item",
                                "Step 1: input number of columns and rows, and click 'Init it'"
                            ),
                            tags$li(
                                class = "list-group-item",
                                "Step 2: Copy paste your data from Excel, and click 'Submit it'"
                            ),
                            tags$li(
                                class = "list-group-item",
                                "Step 3: Click 'Column Types' and change the types of your variables"
                            ),
                            tags$li(
                                class = "list-group-item",
                                "Step 4: Click 'Column Names' and change the names of your variables"
                            ),
                            tags$li(
                                class = "list-group-item",
                                "Step 5: input a linear model formula, and click 'Test it'"
                            )
                        ),
                        tags$div(
                            class = "text-right",
                            actionButton("hideHelp", "Kick off",
                                         class = "btn-success")
                        )
                    )
                )
            )
        )
    ),
    sidebar_collapsed = TRUE
)

# Define server logic required to draw a histogram
server <- function(input, output, session) {
    shinyjs::hide(id = "my-data-table")
    # Initialize the data
    data = reactiveValues(
        nrow = 1, ncol = 1,
        coltype = NULL,
        data=as.data.frame(matrix(NA))
    )
    # Update data
    observeEvent(input$data_submit_btn, {
        newData = as.data.frame(hot_to_r(input$dataTable))
        if(nrow(newData) == data$nrow & ncol(newData) == data$ncol){
            data$data = newData
            showModal(alertModal("success", "Data imported"))
        } else {
            showModal(alertModal("error", "Something went wrong.."))
            dataInit(input, data)
        }
    })

    # Define the output of the data table
    output$dataTable = renderRHandsontable(
        rhandsontable(data$data) %>%
            hot_cols(colWidths = 100)
    )
    shinyjs::js$addInlineCss()
    # Initialize it with empty data
    observeEvent(input$init, {
        shinyjs::show(id="my-data-table")
        shinyjs::hide(id="help-page")
        dataInit(input, data)
        # Reset the formula input if any
        updateTextInput(session, "formula", value = "")
    })
    # Define the column type modal
    observeEvent(input$coltype_btn, {
        showModal(modalDialog(
            title = "Column Types",
            size = "l",
            rHandsontableOutput("colTypeData"),
            footer = tagList(
                actionButton("coltype_submit", "Submit", class="btn-primary"),
                modalButton("Cancel")
            )
        ))
        # Format the cancel button in column type modal
        shinyjs::addClass(class="btn-danger", selector = ".modal-footer button[data-dismiss='modal']")
        shinyjs::removeClass(class = "btn-default", selector = ".modal-footer .btn")
    })
    # Define the output of column types
    output$colTypeData = renderRHandsontable({
        DF = data.frame(t(data$coltype), stringsAsFactors = FALSE)
        htb = rhandsontable(DF, height = 200)
        type_list = c("numeric", "character", "integer", "factor")
        for(i in names(data$coltype)) {
            htb = htb %>%
                hot_col(col = i, type = "dropdown", source = type_list)
        }
        htb %>% hot_cols(colWidths = 100)
    })
    # Column type modal submit event
    observeEvent(input$coltype_submit, {
        newTypes = as.character(hot_to_r(input$colTypeData))
        if( any(newTypes != data$coltype)){
            for(i in seq_along(newTypes)) {
                if(class(data$data[,i]) != newTypes[i]){
                    if(any(data$data[,i] != "")){
                        if(newTypes[i] == "numeric"){
                            data$data[,i] = as.numeric(data$data[,i])
                        } else if (newTypes[i] == "character") {
                            data$data[,i] = as.character(data$data[,i])
                        } else if (newTypes[i] == "integer") {
                            data$data[,i] = integer(data$data[,i])
                        } else if (newTypes[i] == "factor") {
                            data$data[,i] = factor(data$data[,i])
                        }
                    } else {
                        if(newTypes[i] == "numeric"){
                            data$data[,i] = numeric(data$nrow)
                        } else if (newTypes[i] == "character") {
                            data$data[,i] = character(data$nrow)
                        } else if (newTypes[i] == "integer") {
                            data$data[,i] = integer(data$nrow)
                        }
                    }
                }
            }
            data$coltype = newTypes
        }
        removeModal()
    })
    # Define the modal for changing of column names
    observeEvent(input$colnames_btn, {
        # Define the table output for colnames changing
        output$hst_colnames = renderRHandsontable({
            coldf = as.data.frame(
                t(colnames(data$data)),
                stringsAsFactors = FALSE
            )
            colnames(coldf) = colnames(data$data)
            rhandsontable(coldf) %>%
                hot_cols(colWidths = 100)
        })
        # Show modal
        showModal(modalDialog(
            style="height: 150px",
            title = "Column Names",
            size = "l",
            rHandsontableOutput("hst_colnames"),
            footer = tagList(
                actionButton("colname_submit", "Submit", class="btn-primary"),
                modalButton("Cancel")
            )
        ))
        # Format the cancel button in column name modal
        shinyjs::addClass(class="btn-danger", selector = ".modal-footer button[data-dismiss='modal']")
        shinyjs::removeClass(class = "btn-default", selector = ".modal-footer .btn")
    })
    # Define the column name change submit
    observeEvent(input$colname_submit, {
        colnames(data$data) = as.character(hot_to_r(input$hst_colnames))
        removeModal()
    })
    # Do the linear model
    observeEvent(input$test, {
        formula = tryCatch(
            as.formula(input$formula),
            error = function(e) return("err")
        )
        if(formula == "err") {
            showModal(alertModal(
                "error",
                "Please input a valid formula. A valid formua should be like: \"value ~ group\". All variables should present in the column names"
            ))
        } else {
            fit = tryCatch(
                lm(formula = formula, data = data$data),
                error = function(e) return(e)
            )
            if(is(fit, "error")) {
                showModal(alertModal("error", fit$message))
            } else {
                output$modalResult = renderText({
                    paste0(capture.output(summary(fit)), collapse = "\n")
                })
                showModal(modalDialog(
                    title = "Linear Modal Result:",
                    verbatimTextOutput("modalResult"),
                    size = 'l',
                    #easyClose = TRUE,
                    footer = modalButton(label = "Back")
                ))
                # Format the cancel button in column name modal
                shinyjs::removeClass(class = "btn-default", selector = ".modal-footer .btn")
                shinyjs::addClass(class = "bg-danger", selector = ".modal-footer .btn")
            }
        }
    })
    # Show help page
    observeEvent(input$showHelp, {
        shinyjs::show(id = "help-page")
        shinyjs::hide(id = "my-data-table")
    })
    # Hide help page
    observeEvent(input$hideHelp, {
        shinyjs::show(id = "my-data-table")
        shinyjs::hide(id = "help-page")
    })
    # Remove btn-default from all btn
    shinyjs::removeClass(class = "btn-default", selector = ".btn")
    # Format the cancel button in column type modal
    shinyjs::addClass(class="btn-danger", selector = ".")
    # Hide the sidebar
    shinyjs::addClass(class="d-none", selector = ".main-sidebar")
    # Always collapse the sidebar
    shinyjs::removeClass(class="sidebar-mini", selector = "body")
}

shinyApp(ui = ui, server = server)