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using Gadfly
using Morsel

app = Morsel.app()

get(app, "/") do req, res
    #If the n parameter was specified, read it
    #e.g. http://localhost:8000/?n=1000
    if haskey(req.state, :url_params) && haskey(req.state[:url_params], "n")
        n = int(req.state[:url_params]["n"])
        println("Read URL parameter n = $n")
    else
        n=3000
        println("Using default parameter n = $n")
    end

    calculate(n)

    """
    <html>
    <title>My first Julia app</title>
    <body>
    <h1>Estimating <em>π</em> using Monte Carlo</h1>

Here is a simple example of estimating the value of <em>π</em>.

Recall that a circle of radius 1 and area <em>π</em> can be inscribed in a square with sides of length 2. If we pick points at random inside the square, the probability of any given point lying in the circle is <em>π / 4</em>.
    
    <script src="http://d3js.org/d3.v3.min.js"></script>
    <script src="gadfly.js"></script>

    <!-- Placed whereever you want the graphic to be rendered. -->
<div id="my_chart"></div>
<script src="output.js"></script>
<script>
draw("#my_chart");
</script>
    <p>Try changing the number of simulation points by specifying the URL parameter <em>n</em>.
    If the URL you used was <pre>http://localhost:8000</pre>
    try changing the URL to <pre>http://localhost:8000/?n=1000</pre>
    </p>
    </body></html>
    """
end

get(app, "/gadfly.js") do req, res
    readall(open("""$(Pkg.dir("Gadfly"))/src/gadfly.js"""))
end

get(app, "/output.js") do req, res
    readall(open("output.js"))
end

function calculate(n::Integer, outfile="output.js")
    #Do a Monte Carlo simulation and render the output with Gadfly
    xs=convert(Array, @parallel [1-2rand() for i=1:n])
    ys=convert(Array, @parallel [1-2rand() for i=1:n])
    incircle=convert(Vector{Bool}, xs.^2 + ys.^2 .< 1)
    pi_guess = 4sum(incircle)/n

    #Plot with Gadfly
    pie_plot = plot(x=xs, y=ys, color=incircle, Geom.point,
    Guide.title("pi = $pi_guess (n=$n)")) #bug: π breaks D3JS output 
    draw(D3(outfile, 5inch, 4.5inch), pie_plot)
    println("Output rendered to $outfile")
end

start(app, 8000)