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

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

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

  def feminidad(nombre)
    nombre = nombre.to_s.upcase
    sql1 = %(
      SELECT COALESCE(frecuencia,0)
      FROM mujeres WHERE nombre='#{nombre}'

    )
    sql2 = %(
    SELECT COALESCE(frecuencia,0)
    FROM hombres WHERE nombre='#{nombre}'
    )

    # Yes this database is upper case
    mujeres = query(sql1)
    mujeres = mujeres.nil? ? 0 : mujeres[0][0].as_i
    hombres = query(sql2)
    hombres = hombres.nil? ? 0 : hombres[0][0].as_i
    if hombres == mujeres == 0
      return 0.5
    end
    return mujeres / (hombres + mujeres)
  end

  def split_por_genero(nombres)
    femeninos = Array(Array(String | Int32)).new
    masculinos = Array(Array(String | Int32)).new
    nombres.map { |n|
      fem = feminidad(n[1])
      # El overlap en 0.5 es intencional!
      if fem >= 0.5
        femeninos << n
      end
      if fem <= 0.5
        masculinos << n
      end
    }
    {
      "f": femeninos,
      "m": masculinos,
    }
  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: año de nacimiento
    # }

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

    p! query

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

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

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

    año = año.to_i?

    if prefijo.nil? && año.nil?
      # Global totals
      sql = %(
      SELECT total, nombre
      FROM totales
      ORDER BY total DESC
      LIMIT 50
      )
    elsif prefijo.nil? && !año.nil?
      # Per-year totals
      sql = %(
        SELECT contador, nombre
        FROM nombres
        WHERE
            anio = '#{año}'
        ORDER BY contador DESC
        LIMIT 50
      )
    elsif !prefijo.nil? && año.nil?
      # Filter only by prefix
      sql = %(
        SELECT total, nombre
        FROM totales
        WHERE
            nombre LIKE '#{prefijo}%'
        ORDER BY total DESC
        LIMIT 50
      )
    else
      # We have both
      sql = %(
        SELECT contador, nombre
        FROM nombres
        WHERE
            anio = '#{año}' AND
            nombre LIKE '#{prefijo}%'
        ORDER BY contador DESC
        LIMIT 50
      )
    end
    results = query(sql)

    if results.nil?
      # This is bad 😀
      return {
        body:        "Que raro, no tengo *idea*!",
        status_code: 200,
        headers:     HTTP::Headers{"Content-Type" => "text/html"},
      }
    end
    datos = results.map { |r|
      [r[0].as_i, r[1].as_s]
    }

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

    if genero
      datos = split_por_genero(datos)[genero]
    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 { |r|
        r[0].to_f / 1000
      }

      xtics = Hash(Float64, String).new
      datos.each_with_index { |r, i|
        xtics[i.to_f] = r[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