add isogrids/labs/hexa

package isogrids

import (

	"crypto/md5"

	"fmt"

	"image/color"

	"io"

	"net/http"

	"github.com/taironas/tinygraphs/colors"

	"github.com/taironas/tinygraphs/draw"

	"github.com/taironas/tinygraphs/extract"

	"github.com/taironas/tinygraphs/write"

)

// Hexa is the handler for /isogrids/hexa

// builds an hexagon from a 10x10 grid with alternate colors.

func Hexa(w http.ResponseWriter, r *http.Request) {

	var err error

	colorMap := colors.MapOfColorThemes()

	size := extract.Size(r)

	h := md5.New()

	io.WriteString(h, "hello")

	key := fmt.Sprintf("%x", h.Sum(nil)[:])

	theme := "frogideas" //extract.Theme(r)

	numColors := 4       //extract.NumColors(r)

	var bg, fg color.RGBA

	if bg, err = extract.Background(r); err != nil {

		bg = colorMap["base"][0]

	}

	if fg, err = extract.Foreground(r); err != nil {

		fg = colorMap["base"][1]

	}

	if val, ok := colorMap[theme]; ok {

		bg = val[0]

		fg = val[1]

	}

	var colors []color.RGBA

	if theme != "base" {

		if _, ok := colorMap[theme]; ok {

			colors = append(colors, colorMap[theme][0:numColors]...)

		} else {

			colors = append(colors, colorMap["base"]...)

		}

	} else {

		colors = append(colors, bg, fg)

	}

	write.ImageSVG(w)

	draw.IsogridsHexa(w, key, colors, size)

}