#!/bin/sh
##############################################################################
# Copyright (c) 2013: fritz-hh from Github (https://github.com/fritz-hh)
##############################################################################

. "./src/config.sh"


# Initialization of variables passed by args
FILE_INPUT_PDF="$1"
PAGE_INFO="$2"
NUM_PAGES="$3"
TMP_FLD="$4"
VERBOSITY="$5"
LAN="$6"
KEEP_TMP="$7"
PREPROCESS_DESKEW="$8"
PREPROCESS_CLEAN="$9"
PREPROCESS_CLEANTOPDF="${10}"
PDF_NOIMG="${11}"
TESS_CFG_FILES="${12}"



page=`echo $PAGE_INFO | cut -f1 -d" "`
[ $VERBOSITY -ge $LOG_INFO ] && echo "Processing page $page / $NUM_PAGES"

# create the name of the required file
curOrigImg="$TMP_FLD/${page}_Image"			# original image available in the current PDF page 
							# (the image file may have a different orientation than in the pdf file)
curHocr="$TMP_FLD/$page.hocr"				# hocr file to be generated by the OCR SW for the current page
curOCRedPDF="$TMP_FLD/${page}-ocred.pdf"		# PDF file containing the image + the OCRed text for the current page
curOCRedPDFDebug="$TMP_FLD/${page}-debug-ocred.pdf"	# PDF file containing data required to find out if OCR worked correctly

# get width / height of PDF page (in pt)
widthPDF=`echo $PAGE_INFO | cut -f2 -d" "`
heightPDF=`echo $PAGE_INFO | cut -f3 -d" "`
[ $VERBOSITY -ge $LOG_DEBUG ] && echo "Page $page: size ${heightPDF}x${widthPDF} (h*w in pt)"
# extract raw image from pdf file to compute resolution
# unfortunately this image can have another orientation than in the pdf...
# so we will have to extract it again later using pdftoppm
pdfimages -f $page -l $page -j "$FILE_INPUT_PDF" "$curOrigImg" 1>&2	
# count number of extracted images
nbImg=`ls -1 "$curOrigImg"* | wc -l`
[ $nbImg -ne "1" ] && echo "Expecting exactly 1 image on page $page (found $nbImg). Exiting..." >&2 && exit $EXIT_BAD_INPUT_FILE
# Get characteristics of the extracted image
curImg=`ls -1 "$curOrigImg"*`
propCurImg=`identify -format "%w %h %[colorspace]" "$curImg"`
widthCurImg=`echo "$propCurImg" | cut -f1 -d" "`
heightCurImg=`echo "$propCurImg" | cut -f2 -d" "`
colorspaceCurImg=`echo "$propCurImg" | cut -f3 -d" "`
# switch height/width values if the image has not the right orientation
# we make here the assumption that vertical/horizontal dpi are equal
# we will check that later
if [ $((($heightPDF-$widthPDF)*($heightCurImg-$widthCurImg))) -lt 0 ]; then
	[ $VERBOSITY -ge $LOG_DEBUG ] && echo "Page $page: Extracted image has wrong orientation. Inverting image height/width values"
	tmpval=$heightCurImg
	heightCurImg=$widthCurImg
	widthCurImg=$tmpval
fi
[ $VERBOSITY -ge $LOG_DEBUG ] && echo "Page $page: size ${heightCurImg}x${widthCurImg} (h*w pixel)"	
# compute the resolution of the image
dpi_x=`echo "scale=5;$widthCurImg*72/$widthPDF" | bc`
dpi_y=`echo "scale=5;$heightCurImg*72/$heightPDF" | bc`
# compute the maximum allowed resolution difference that can be cause by:
# - the truncated PDF with/height in pt
# - the precision of dpi value
epsilon=`echo "scale=5;($widthCurImg*72/$widthPDF^2)+($heightCurImg*72/$heightPDF^2)+0.00002" | bc`	# max inaccuracy due to truncation of PDF size in pt
[ `echo "($dpi_x - $dpi_y) < $epsilon " | bc` -eq 0 -o `echo "($dpi_y - $dpi_x) < $epsilon " | bc` -eq 0 ] \
	&& echo "Resolutions difference ($dpi_x/$dpi_y) higher than expected ($epsilon). Exiting..." >&2 && exit $EXIT_BAD_INPUT_FILE
dpi=`echo "scale=5;($dpi_x+$dpi_y)/2+0.5" | bc` # adding 0.5 is required for rounding
dpi=`echo "scale=0;$dpi/1" | bc`		# round to the nearest integer

# Identify if page image should be saved as ppm (color) or pgm (gray)
ext="ppm"
opt=""		
if [ $colorspaceCurImg == "Gray" ]; then
	ext="pgm"
	opt="-gray"
fi
curImgPixmap="$TMP_FLD/$page.$ext"
curImgPixmapDeskewed="$TMP_FLD/$page.deskewed.$ext"
curImgPixmapClean="$TMP_FLD/$page.cleaned.$ext"

# extract current page as image with right orientation and resoltution
[ $VERBOSITY -ge $LOG_DEBUG ] && echo "Page $page: Extracting image as $ext file (${dpi} dpi)"
! pdftoppm -f $page -l $page -r $dpi $opt "$FILE_INPUT_PDF" > "$curImgPixmap" \
	&& echo "Could not extract page $page as $ext from \"$FILE_INPUT_PDF\". Exiting..." >&2 && exit $EXIT_OTHER_ERROR

# if requested deskew image (without changing its size in pixel)
if [ "$PREPROCESS_DESKEW" -eq "1" ]; then
	[ $VERBOSITY -ge $LOG_DEBUG ] && echo "Page $page: Deskewing image"
	! convert "$curImgPixmap" -deskew 40% -gravity center -extent ${widthCurImg}x${heightCurImg} "$curImgPixmapDeskewed" \
		&& echo "Could not deskew \"$curImgPixmap\". Exiting..." >&2 && exit $EXIT_OTHER_ERROR
else
	cp "$curImgPixmap" "$curImgPixmapDeskewed"
fi

# if requested clean image with unpaper to get better OCR results
if [ "$PREPROCESS_CLEAN" -eq "1" ]; then
	[ $VERBOSITY -ge $LOG_DEBUG ] && echo "Page $page: Cleaning image with unpaper"
	! unpaper --dpi $dpi --mask-scan-size 100 \
		--no-deskew --no-grayfilter --no-blackfilter --no-mask-center --no-border-align \
		"$curImgPixmapDeskewed" "$curImgPixmapClean" 1> /dev/null \
		&& echo "Could not clean \"$curImgPixmapDeskewed\". Exiting..." >&2 && exit $EXIT_OTHER_ERROR
else
	cp "$curImgPixmapDeskewed" "$curImgPixmapClean"
fi

# perform OCR
[ $VERBOSITY -ge $LOG_DEBUG ] && echo "Page $page: Performing OCR"
! tesseract -l "$LAN" "$curImgPixmapClean" "$curHocr" hocr $TESS_CFG_FILES 1> /dev/null 2> /dev/null \
	&& echo "Could not OCR file \"$curImgPixmapClean\". Exiting..." >&2 && exit $EXIT_OTHER_ERROR
mv "$curHocr.html" "$curHocr"

# embed text and image to new pdf file
if [ "$PREPROCESS_CLEANTOPDF" -eq "1" ]; then
	image4finalPDF="$curImgPixmapClean"
else
	image4finalPDF="$curImgPixmapDeskewed"	
fi
[ $VERBOSITY -ge $LOG_DEBUG ] && echo "Page $page: Embedding text in PDF"
! python2 $SRC/hocrTransform.py -r $dpi -i "$image4finalPDF" "$curHocr" "$curOCRedPDF" \
	&& echo "Could not create PDF file from \"$curHocr\". Exiting..." >&2 && exit $EXIT_OTHER_ERROR

# if requested generate special debug PDF page with visible OCR text
if [ $PDF_NOIMG -eq "1" ] ; then
	[ $VERBOSITY -ge $LOG_DEBUG ] && echo "Page $page: Embedding text in PDF (debug page)"
	! python2 $SRC/hocrTransform.py -b -r $dpi "$curHocr" "$curOCRedPDFDebug" \
		&& echo "Could not create PDF file from \"$curHocr\". Exiting..." >&2 && exit $EXIT_OTHER_ERROR	
fi

# delete temporary files created for the current page
# to avoid using to much disk space in case of PDF files having many pages
if [ $KEEP_TMP -eq 0 ]; then
	rm "$curOrigImg"*.*
	rm "$curHocr"
	rm "$curImgPixmap"
	rm "$curImgPixmapDeskewed"
	rm "$curImgPixmapClean"
fi

exit 0