#' Create a apexcharts.js widget
#'
#' @param ax_opts A \code{list} in JSON format with chart parameters.
#' @param auto_update In Shiny application, update existing chart rather than generating new one.
#' @param width A numeric input in pixels.
#' @param height A numeric input in pixels.
#' @param elementId Use an explicit element ID for the widget.
#'
#' @return A \code{apexcharts} \code{htmlwidget} object.
#' @export
#'
#' @importFrom htmlwidgets createWidget sizingPolicy
#'
#' @examples
#'
#' library(apexcharter)
#' 
#' # Use raw API by passing a list of
#' # parameters to the function
#' 
#' apexchart(ax_opts = list(
#'   chart = list(
#'     type = "bar"
#'   ),
#'   series = list(list(
#'     name = "Example",
#'     data = sample(1:100, 5)
#'   )),
#'   xaxis = list(
#'     categories = LETTERS[1:5]
#'   )
#' ))
#' 
#' 
#' # Or use apexchart() to initialize the chart
#' # before passing parameters
#' 
#' apexchart() %>% 
#'   ax_chart(type = "bar") %>% 
#'   ax_series(
#'     list(
#'       name = "Example",
#'       data = sample(1:100, 5)
#'     )
#'   ) %>% 
#'   ax_xaxis(
#'     categories = LETTERS[1:5]
#'   )
#'   
apexchart <- function(ax_opts = list(), auto_update = TRUE, width = NULL, height = NULL, elementId = NULL) {

  # forward options using x
  x <- list(
    ax_opts = ax_opts,
    auto_update = auto_update
  )

  # create widget
  htmlwidgets::createWidget(
    name = 'apexcharter',
    x = x,
    width = width,
    height = height,
    package = 'apexcharter',
    elementId = elementId,
    sizingPolicy = htmlwidgets::sizingPolicy(
      defaultWidth = "100%",
      defaultHeight = "100%",
      viewer.defaultHeight = "100%",
      viewer.defaultWidth = "100%",
      knitr.figure = FALSE,
      knitr.defaultWidth = "100%",
      knitr.defaultHeight = "350px",
      browser.fill = TRUE,
      viewer.suppress = FALSE,
      browser.external = TRUE,
      padding = 20
    )
  )
}

#' @title Shiny bindings for apexcharter
#'
#' @description Output and render functions for using apexcharter within Shiny
#' applications and interactive Rmd documents.
#'
#' @param outputId output variable to read from
#' @param width,height Must be a valid CSS unit (like \code{'100\%'},
#'   \code{'400px'}, \code{'auto'}) or a number, which will be coerced to a
#'   string and have \code{'px'} appended.
#' @param expr An expression that generates a apexcharter
#' @param env The environment in which to evaluate \code{expr}.
#' @param quoted Is \code{expr} a quoted expression (with \code{quote()})? This
#'   is useful if you want to save an expression in a variable.
#'   
#' @return An Apexchart output that can be included in the application UI.
#'
#' @name apexcharter-shiny
#'
#' @export
#'
#' @importFrom htmlwidgets shinyWidgetOutput shinyRenderWidget
#' 
#' @examples 
#' 
#' if (interactive()) {
#'   library(shiny)
#'   
#'   ui <- fluidPage(
#'     fluidRow(
#'       column(
#'         width = 8, offset = 2,
#'         tags$h2("Apexchart in Shiny"),
#'         actionButton("redraw", "Redraw chart"),
#'         apexchartOutput("chart")
#'       )
#'     )
#'   )
#'   
#'   server <- function(input, output, session) {
#'     
#'     output$chart <- renderApexchart({
#'       input$redraw
#'       apexchart() %>%
#'         ax_chart(type = "bar") %>%
#'         ax_series(
#'           list(
#'             name = "Example",
#'             data = sample(1:100, 5)
#'           )
#'         ) %>%
#'         ax_xaxis(
#'           categories = LETTERS[1:5]
#'         )
#'     })
#'     
#'   }
#'   
#'   shinyApp(ui, server)
#' }
apexchartOutput <- function(outputId, width = '100%', height = '400px'){
  htmlwidgets::shinyWidgetOutput(outputId, 'apexcharter', width, height, package = 'apexcharter')
}

#' @rdname apexcharter-shiny
#' @export
renderApexchart <- function(expr, env = parent.frame(), quoted = FALSE) {
  if (!quoted) { expr <- substitute(expr) } # force quoted
  htmlwidgets::shinyRenderWidget(expr, apexchartOutput, env, quoted = TRUE)
}