require "http/client"
require "http/headers"
require "http/request"
require "ishi/html"
require "json"
require "uuid"

class Handler
  def format_buffer(buffer, canvas_name, title = "")
    # Process the gnuplot output so it works in the page
    #
    # buffer is the Ishi output
    # name is a string to replace for gnuplot_canvas so
    #      we can have multiple charts in a page
    # title is added on top of the chart

    html = buffer.to_s.split("\n")
    html = html[html.index("<script type=\"text/javascript\">")..html.index("</script>")]
    html = "<b>#{title}</b>" + html.join("\n") + %(
    <div class="gnuplot">
    <canvas id="Tile" width="32" height="32" hidden></canvas>
    <table class="plot">
    <tr><td>
    <canvas id="gnuplot_canvas" width="800" height="300" tabindex="0">
    Sorry, your browser seems not to support the HTML 5 canvas element
    </canvas>
    </td></tr>
    </table>
    <script type="text/javascript" defer>
    gnuplot.init(); gnuplot_canvas();
    </script>
    </div>
    )
    # This ID needs to be unique in case
    # we have 2 charts in the same page
    html.gsub("gnuplot_canvas", canvas_name)
  end

  def query(sql)
    # Runs a SQL query against the Rqlite database.
    #
    # Returns an array of values (which need to be casted)
    # Or nil if there are no results

    params = URI::Params.encode({"q": sql})
    response = HTTP::Client.get URI.new(
      "http",
      "10.61.0.1",
      4001,
      "/db/query",
      params)

    # This API only has a values key when there are actual results
    results = JSON.parse(response.body)["results"][0].as_h
    if results.has_key?("values")
      return results["values"].as_a
    end
    # No result, return nil
    nil
  end

  nombres = [] of String

  def normalize_name(s)
    # Remove diacritics, turn lowercase
    normalized = s.unicode_normalize(:nfkd).chars
    normalized.reject! { |c|
      !c.ascii_letter?
    }.join("").downcase
  end

  def run(request : HTTP::Request)
    unless (body = request.body).nil?
      query = JSON.parse(body)
      nombres = query["i"].as_s.split(",").map { |n| n.strip }
      nombres.reject! { |n| n.size == 0 }
    end

    if nombres.nil? || nombres.empty?
      nombres = ["maria", "juan"]
    end

    # Remove all diacritics and whatnot
    nombres = nombres.map { |n|
      normalize_name n
    }

    puts "Processing #{nombres}"

    buffer = IO::Memory.new
    Ishi.new(buffer) do
      canvas_size(800, 300)
      show_key(true)
      xrange(1922..2015)
      nombres.map { |nombre|
        sql = "SELECT anio, contador FROM nombres WHERE nombre = '#{nombre}' ORDER BY anio"
        x = Array(Int32).new
        y = Array(Int32).new
        results = query(sql)
        if results.nil?  # No results, all 0s
          x = (1922..2015).to_a
          y = x.map {|_| 0}
        else  # We got results
          displayed = true
          results.map { |r|
            x << r[0].as_i
            y << r[1].as_i
          }
        end
        plot(x, y, title: nombre.titleize, style: :lines, linewidth: 3)
      }
    end

    return {
      body:        format_buffer(buffer, "historico"),
      status_code: 200,
      headers:     HTTP::Headers{"Content-Type" => "text/html"},
    }
  end
end