defaultOutputFormat(plt::Plot) = "png"

function png(plt::Plot, fn::AbstractString)
  fn = addExtension(fn, "png")
  io = open(fn, "w")
  show(io, MIME("image/png"), plt)
  close(io)
end
png(fn::AbstractString) = png(current(), fn)

function svg(plt::Plot, fn::AbstractString)
  fn = addExtension(fn, "svg")
  io = open(fn, "w")
  show(io, MIME("image/svg+xml"), plt)
  close(io)
end
svg(fn::AbstractString) = svg(current(), fn)


function pdf(plt::Plot, fn::AbstractString)
  fn = addExtension(fn, "pdf")
  io = open(fn, "w")
  show(io, MIME("application/pdf"), plt)
  close(io)
end
pdf(fn::AbstractString) = pdf(current(), fn)


function ps(plt::Plot, fn::AbstractString)
  fn = addExtension(fn, "ps")
  io = open(fn, "w")
  show(io, MIME("application/postscript"), plt)
  close(io)
end
ps(fn::AbstractString) = ps(current(), fn)

function eps(plt::Plot, fn::AbstractString)
  fn = addExtension(fn, "eps")
  io = open(fn, "w")
  show(io, MIME("image/eps"), plt)
  close(io)
end
eps(fn::AbstractString) = eps(current(), fn)

function tex(plt::Plot, fn::AbstractString)
  fn = addExtension(fn, "tex")
  io = open(fn, "w")
  show(io, MIME("application/x-tex"), plt)
  close(io)
end
tex(fn::AbstractString) = tex(current(), fn)

function html(plt::Plot, fn::AbstractString)
    fn = addExtension(fn, "html")
    io = open(fn, "w")
    _use_remote[] = true
    show(io, MIME("text/html"), plt)
    _use_remote[] = false
    close(io)
end
html(fn::AbstractString) = html(current(), fn)


# ----------------------------------------------------------------


const _savemap = Dict(
    "png" => png,
    "svg" => svg,
    "pdf" => pdf,
    "ps"  => ps,
    "eps" => eps,
    "tex" => tex,
    "html" => html,
  )

function getExtension(fn::AbstractString)
  pieces = split(fn, ".")
  length(pieces) > 1 || error("Can't extract file extension: ", fn)
  ext = pieces[end]
  haskey(_savemap, ext) || error("Invalid file extension: ", fn)
  ext
end

function addExtension(fn::AbstractString, ext::AbstractString)
  try
    oldext = getExtension(fn)
    if oldext == ext
      return fn
    else
      return "$fn.$ext"
    end
  catch
    return "$fn.$ext"
  end
end

"""
    savefig([plot,] filename)

Save a Plot (the current plot if `plot` is not passed) to file. The file
type is inferred from the file extension. All backends support png and pdf
file types, some also support svg, ps, eps, html and tex.
"""
function savefig(plt::Plot, fn::AbstractString)

  # get the extension
  local ext
  try
    ext = getExtension(fn)
  catch
    # if we couldn't extract the extension, add the default
    ext = defaultOutputFormat(plt)
    fn = addExtension(fn, ext)
  end

  # save it
  func = get(_savemap, ext) do
    error("Unsupported extension $ext with filename ", fn)
  end
  func(plt, fn)
end
savefig(fn::AbstractString) = savefig(current(), fn)


# ---------------------------------------------------------
"""
    gui([plot])

Display a plot using the backends' gui window
"""
gui(plt::Plot = current()) = display(PlotsDisplay(), plt)

# IJulia only... inline display
function inline(plt::Plot = current())
    isijulia() || error("inline() is IJulia-only")
    Main.IJulia.clear_output(true)
    display(Main.IJulia.InlineDisplay(), plt)
end

function Base.display(::PlotsDisplay, plt::Plot)
    prepare_output(plt)
    _display(plt)
end

# override the REPL display to open a gui window
Base.display(::Base.REPL.REPLDisplay, ::MIME"text/plain", plt::Plot) = gui(plt)


_do_plot_show(plt, showval::Bool) = showval && gui(plt)
function _do_plot_show(plt, showval::Symbol)
    showval == :gui && gui(plt)
    showval in (:inline,:ijulia) && inline(plt)
end

# ---------------------------------------------------------

const _mimeformats = Dict(
    "application/eps"         => "eps",
    "image/eps"               => "eps",
    "application/pdf"         => "pdf",
    "image/png"               => "png",
    "application/postscript"  => "ps",
    "image/svg+xml"           => "svg",
    "text/plain"              => "txt",
    "application/x-tex"       => "tex",
)

const _best_html_output_type = KW(
    :pyplot => :png,
    :unicodeplots => :txt,
    :glvisualize => :png
)

# a backup for html... passes to svg or png depending on the html_output_format arg
function Base.show(io::IO, ::MIME"text/html", plt::Plot)
    output_type = Symbol(plt.attr[:html_output_format])
    if output_type == :auto
        output_type = get(_best_html_output_type, backend_name(plt.backend), :svg)
    end
    if output_type == :png
        # info("writing png to html output")
        print(io, "<img src=\"data:image/png;base64,", base64encode(show, MIME("image/png"), plt), "\" />")
    elseif output_type == :svg
        # info("writing svg to html output")
        show(io, MIME("image/svg+xml"), plt)
    elseif output_type == :txt
        show(io, MIME("text/plain"), plt)
    else
        error("only png or svg allowed. got: $output_type")
    end
end

function _show(io::IO, m, plt::Plot{B}) where B
    # Base.show_backtrace(STDOUT, backtrace())
    warn("_show is not defined for this backend. m=", string(m))
end
function _display(plt::Plot)
    warn("_display is not defined for this backend.")
end

# for writing to io streams... first prepare, then callback
for mime in keys(_mimeformats)
    @eval function Base.show(io::IO, m::MIME{Symbol($mime)}, plt::Plot{B}) where B
        prepare_output(plt)
        _show(io, m, plt)
    end
end

"Close all open gui windows of the current backend"
closeall() = closeall(backend())


# ---------------------------------------------------------
# A backup, if no PNG generation is defined, is to try to make a PDF and use FileIO to convert

if is_installed("FileIO")
    @eval import FileIO
    function _show(io::IO, ::MIME"image/png", plt::Plot)
        fn = tempname()

        # first save a pdf file
        pdf(plt, fn)

        # load that pdf into a FileIO Stream
        s = FileIO.load(fn * ".pdf")

        # save a png
        pngfn = fn * ".png"
        FileIO.save(pngfn, s)

        # now write from the file
        write(io, readstring(open(pngfn)))
    end
end

# function html_output_format(fmt)
#     if fmt == "png"
#         @eval function Base.show(io::IO, ::MIME"text/html", plt::Plot)
#             print(io, "<img src=\"data:image/png;base64,", base64(show, MIME("image/png"), plt), "\" />")
#         end
#     elseif fmt == "svg"
#         @eval function Base.show(io::IO, ::MIME"text/html", plt::Plot)
#             show(io, MIME("image/svg+xml"), plt)
#         end
#     else
#         error("only png or svg allowed. got: $fmt")
#     end
# end
#
# html_output_format("svg")

# ---------------------------------------------------------
# IJulia
# ---------------------------------------------------------

const _ijulia_output = String["text/html"]

@require IJulia begin
    if IJulia.inited
        export set_ijulia_output

        function set_ijulia_output(mimestr::AbstractString)
            # info("Setting IJulia output format to $mimestr")
            global _ijulia_output
            _ijulia_output[1] = mimestr
        end
        function IJulia.display_dict(plt::Plot)
            global _ijulia_output
            Dict{String, String}(_ijulia_output[1] => sprint(show, _ijulia_output[1], plt))
        end

        # default text/plain passes to html... handles Interact issues
        function Base.show(io::IO, m::MIME"text/plain", plt::Plot)
            show(io, MIME("text/html"), plt)
        end

        ENV["MPLBACKEND"] = "Agg"
        set_ijulia_output("text/html")
    end
end

# ---------------------------------------------------------
# Atom PlotPane
# ---------------------------------------------------------
@require Juno begin
    import Hiccup, Media

    if Juno.isactive()
        Media.media(Plot, Media.Plot)


        _show(io::IO, m::MIME"text/plain", plt::Plot{B}) where {B} = print(io, "Plot{$B}()")

        function Juno.render(e::Juno.Editor, plt::Plot)
            Juno.render(e, nothing)
        end

        if get(ENV, "PLOTS_USE_ATOM_PLOTPANE", true) in (true, 1, "1", "true", "yes")
            function Juno.render(pane::Juno.PlotPane, plt::Plot)
                # temporarily overwrite size to be Atom.plotsize
                sz = plt[:size]
                jsize = Juno.plotsize()
                jsize[1] == 0 && (jsize[1] = 400)
                jsize[2] == 0 && (jsize[2] = 500)

                plt[:size] = jsize
                Juno.render(pane, HTML(stringmime(MIME("text/html"), plt)))
                plt[:size] = sz
            end
            # special handling for PlotlyJS
            function Juno.render(pane::Juno.PlotPane, plt::Plot{PlotlyJSBackend})
                display(Plots.PlotsDisplay(), plt)
            end
        else
            function Juno.render(pane::Juno.PlotPane, plt::Plot)
                display(Plots.PlotsDisplay(), plt)
                s = "PlotPane turned off.  Unset ENV[\"PLOTS_USE_ATOM_PLOTPANE\"] and restart Julia to enable it."
                Juno.render(pane, HTML(s))
            end
        end

        # special handling for plotly... use PlotsDisplay
        function Juno.render(pane::Juno.PlotPane, plt::Plot{PlotlyBackend})
            display(Plots.PlotsDisplay(), plt)
            s = "PlotPane turned off.  The plotly backend cannot render in the PlotPane due to javascript issues. Plotlyjs is similar to plotly and is compatible with the plot pane."
            Juno.render(pane, HTML(s))
        end
    end
end