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

USER   = File.read("/var/openfaas/secrets/nombres-user").strip
PASS   = File.read("/var/openfaas/secrets/nombres-pass").strip
DB_URL = "postgres://#{USER}:#{PASS}@10.61.0.1:5432/nombres"

class Handler
  # This class is the entry point for the OpenFaaS function.
  # run() is the important bit

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

  def run(request : HTTP::Request)
    # Try to find most popular names based on a prefix, year and gender.
    #
    # Request body is JSON in this form:
    #
    # {
    #     p: prefijo del nombre,
    #     g: genero del nombre,
    #     y: year de nacimiento
    # }

    if (body = request.body).nil?
      query = {"p": "", "g": "", "a": ""}
    else
      query = Hash(String, String).from_json(body)
    end

    # Sanitize input.
    # Each one either a valid string or nil
    prefijo = query.fetch("p", "")
    genero = query.fetch("g", "")
    year = query.fetch("y", "")

    if !prefijo.empty?
      prefijo = normalize_name(prefijo)
    else
      prefijo = nil
    end

    if !["f", "m"].includes?(genero)
      genero = nil
    end

    year = year.to_i?

    datos = [] of Tuple(Int32, String)
    DB.open(DB_URL) do |cursor|
      if prefijo.nil? && year.nil?
        # Global totals
        result_set = cursor.query("
          SELECT total::integer, nombre
          FROM totales
          ORDER BY total DESC
          LIMIT 50")
      elsif prefijo.nil? && !year.nil?
        # Per-year totals
        result_set = cursor.query("
          SELECT contador::integer, nombre
          FROM nombres
          WHERE
            anio = $1
          ORDER BY contador DESC
          LIMIT 50", year)
      elsif !prefijo.nil? && year.nil?
        # Filter only by prefix
        result_set = cursor.query("
          SELECT total::integer, nombre
          FROM totales
          WHERE
              nombre LIKE $1
          ORDER BY total DESC
          LIMIT 50", prefijo + "%")
      elsif !prefijo.nil? && !year.nil?
        # We have both
        result_set = cursor.query("
          SELECT contador::integer, nombre
          FROM nombres
          WHERE
              anio = $1 AND
              nombre LIKE $2
          ORDER BY contador DESC
          LIMIT 50", year, prefijo + "%")
      end

      if !result_set.nil?
        result_set.each do
          valor = result_set.read(Int32)
          nombre = result_set.read(String)
          datos.push({valor, nombre})
        end
        result_set.close
      end
    end

    puts "Data gathered"

    if datos.empty?
      # This is bad 😀
      return {
        body:        "Que raro, no tengo *idea*!",
        status_code: 200,
        headers:     HTTP::Headers{"Content-Type" => "text/html"},
      }
    end

    # In this context, remove all composite names
    datos.reject! { |row|
      row[1].to_s.includes? " "
    }

    if genero
      DB.open(DB_URL) do |cursor|
        datos.reject! { |row|
          # How feminine is this name?
          # Yes this database is upper case
          puts "Checking #{row[0]} #{row[1]}"
          feminidad = 0
          sql = %(
            SELECT COALESCE((SELECT frecuencia FROM mujeres WHERE nombre='#{row[1]?.to_s.upcase}'), 0) AS mujeres,
                   COALESCE((SELECT frecuencia FROM hombres WHERE nombre='#{row[1]?.to_s.upcase}'), 0) AS hombres
          )
          puts "SQL: #{sql}"
          cursor.query sql do |result_set|
            result_set.each do
              mujeres = result_set.read(Int32)
              hombres = result_set.read(Int32)
              puts "frecuencias: #{mujeres} #{hombres}"
              if hombres == mujeres == 0
                feminidad = 0.5
              else
                feminidad = mujeres / (hombres + mujeres)
              end
            end
          end
          # El overlap en 0.5 es intencional!
          if (feminidad >= 0.5 && genero == "f") ||
             (feminidad <= 0.5 && genero == "m")
            false
          else
            true
          end
        }
        puts "Data split by gender"
      end
    end
    datos = datos[..10]

    if datos.size > 1
      title = "¿Puede ser ... #{datos[0][1].to_s.titleize}? ¿O capaz que #{datos[1][1].to_s.titleize}? ¡Contame más!"
    elsif datos.size == 1
      title = "Me parece que ... #{datos[0][1].to_s.titleize}!"
    else
      title = "No tengo idea!"
    end

    buffer = IO::Memory.new
    Ishi.new(buffer) do
      x = (0..datos.size - 1).to_a
      y = datos.map { |row|
        row[0].to_f / 1000
      }
      yrange(0..(y.max*1.1).to_i + 1)

      xtics = Hash(Float64, String).new
      datos.each_with_index { |row, i|
        xtics[i.to_f] = row[1].to_s.titleize
      }

      canvas_size(800, 300)
      plot(x, y, style: :boxes, fs: 0.25)
        .boxwidth(0.5)
        .show_key(false)
        .ylabel("Popularidad (miles)")
        .xtics(xtics)
    end

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