#! /usr/bin/env bash
# erd2map
#
#      Create html map file from one of Marc's pretty ERDs
#
#      Copyright (c) 2020 Marc Munro
#      Author:  Marc Munro
#      License: GPL V3
#
# Usage:
# erd2map <image-basename> <htmlroot>
#
# This requires the existence of files:
# - <image_basename>.png    (created from dia source by dia and pstoimg)
# - <image_basename>.coords (created from dia source by xsltproc)
#
# The coords file (see stylesheet dia_to_map.xsl) consists of a bunch
# of entity and point definitions in dia gird coordinates.
#

# scale_factors()
# From our coords file and the size of the image work out scale
# factors and offsets, printing output lines for for each to stdout.
# Usage: scale_factors <size> <coords-file>
# 
scale_factors () {
    gawk -v SIZE=$1 'BEGIN {
           min_x = 100000
           min_y = 100000
           max_x = 0
           max_y = 0
           x_pixels = gensub(/x.*/, "", "g", SIZE) + 0
           y_pixels = gensub(/.*x/, "", "g", SIZE) + 0
    }
    /x=/ {
    	x = gensub(/.*x=.([-0-9.]*).*/, "\\1", "g") + 0
    	y = gensub(/.*y=.([-0-9.]*).*/, "\\1", "g") + 0
    	if (x > max_x) max_x = x
    	if (y > max_y) max_y = y
    	if (x < min_x) min_x = x
    	if (y < min_y) min_y = y
    }
    END	{
    	x_range = max_x - min_x
    	y_range = max_y - min_y
    	x_scale = x_pixels / x_range
    	y_scale = y_pixels / y_range
    	x_offset = -min_x * x_scale
    	y_offset = -min_y * y_scale
    	print "SCALE:", x_scale, y_scale
    	print "OFFSET:", x_offset, y_offset
    }
    ' $2
}

# Get html references for entities, printing the results to stdout.
# Usage: cat entity_list | entity_refs <html-dir> 
#
find_refs ()
{
    export ref_object=$2
    ( cd $1
      while read line; do
	  if files=`grep -l "${ref_object}_${line}" *html` 2>/dev/null; then
	      file=`echo "${files}" | head -1`
	      echo "REFOBJECT $line ${file}#${ref_object}_${line}"
	  fi
      done
    )
}

# Create html area definitions for each entity based on scale factors
# and the entities' html refs.
#
make_areas () {
    (cat - $1) | gawk -v BASENAME="$2" -v OBJTYPE="${objtype}" '
    # Read coordinates attributes from a coords file line.
    function coords() {
        x = int(gensub(/.*x=\"([^\"]*).*/, "\\1", "g") * x_scale + x_offset)
        y = int(gensub(/.*y=\"([^\"]*).*/, "\\1", "g") * y_scale + y_offset)

	#print $0, x, y
	return x "," y
    }
    BEGIN {
        if (OBJTYPE == "view") {
	    obj_tail = " view"
	}
	else {
	    obj_tail = "s table"
	}
        printf("<div id=\"%s_div\">\n", BASENAME)
        printf("  <map name=\"%s_map\">\n", BASENAME)
    }
    END {
        printf("  </map>\n")
	printf("  <img src=\"%s.png\" usemap=\"#%s_map\">\n", 
	       BASENAME, BASENAME)
	printf("</div>\n")
    }
    # Read x and y scale factors.
    /^SCALE: / {
        x_scale = $2 + 0
        y_scale = $3 + 0
	#print "SCALE:", x_scale, y_scale
    }
    # Read x and y pixel offsets
    /^OFFSET: / {
        x_offset = $2 + 0
        y_offset = $3 + 0
	#print "OFFSET:", x_offset, y_offset
    }
    # Create array (hash, really) of html_refs keyed by refobjects
    /^REFOBJECT/ {
        html_refs[$2] = gensub(/[^ ]* [^ ]* (.*)/, "\\1", "g")        
    }
    # Read refobject name, and get html reference for it.
    /<refobject/ {
        refobject_name = gensub(/.*value=\"([^\"]*).*/, "\\1", "g")
	if (refobject_name in html_refs) {
	    href = html_refs[refobject_name]
	}
	else {
	    href = ""
	}
    }
    /<top-left/ {
        top_left = coords()
    }
    /<bottom-right/ {
        if (href != "") {
 	   bottom_right = coords()
	   printf("    <area alt=\"%s entity\" title=\"%s%s\"\n",
           	  refobject_name, refobject_name, obj_tail)
	   printf("      target=\"_self\" shape=\"rect\"\n")
	   printf("      coords=\"%s,%s\"\n", top_left, bottom_right)
	   printf("      href=\"%s\">\n", href)
       }
    }' 
}

# Get entities from coords file
# Usage: entities <coords_file>
#
referenced_objects ()
{
    gawk '/<refobject/ { print gensub(/.*value=\"([^\"]*).*/, "\\1", "g") }' $1
}

if [ "x$1" = "x-v" ]; then
    export objtype=view
    shift
else
    export objtype=table
fi

thisdir=`basename $0`
diagram_basename=`basename $1`

# Get dimensions of image.
size=`identify -format "%[w]x%[h]" $1.png`

if [ "x$3" = "x" ]; then
    ref_prefix="entity"
else
    ref_prefix="$3"
fi

(
  referenced_objects $1.coords | find_refs $2 ${ref_prefix}
  scale_factors ${size} $1.coords
) | make_areas $1.coords ${diagram_basename}