#!/usr/bin/env bash
# Builds a *filtered* ICU 68 data package with only the converters libmspub
# asks for, and turns it into a C source file that the binding registers with
# udata_setCommonData().
#
# Why: the emscripten ICU port links libicu_stubdata (no data at all), so
# ucnv_open("windows-1252") fails with U_FILE_ACCESS_ERROR. libmspub needs
# codepage converters for (a) Publisher 97 text (MSPUBParser97, encoding
# guessed with ucsdet) and (b) the OLE SummaryInformation metadata
# (always "windows-1252"). UTF-16LE (Publisher 2000+ text) is algorithmic and
# works without data.
#
# Converters come from libmspub_utils.cpp windowsCharsetNameByOriginalCharset()
# and MSPUBMetaData.cpp. Canonical ICU names (convrtrs.txt, ICU 68):
#   windows-1250 -> ibm-5346_P100-1998     windows-1251 -> ibm-5347_P100-1998
#   windows-1252 -> ibm-5348_P100-1997     windows-1256 -> ibm-9448_X100-2005
#   windows-932  -> ibm-943_P15A-2003      windows-936  -> windows-936-2000
#   windows-950  -> windows-950-2000
#
#   make-icudata.sh <outdir>
set -euo pipefail
OUT="${1:?outdir}"
SRC="$(em-config CACHE)/ports/icu/icu/source/data/in/icudt68l.dat"
WORK="$(mktemp -d)"
mkdir -p "${OUT}"

ITEMS=(
  cnvalias.icu
  ibm-5346_P100-1998.cnv
  ibm-5347_P100-1998.cnv
  ibm-5348_P100-1997.cnv
  ibm-9448_X100-2005.cnv
  ibm-943_P15A-2003.cnv
  windows-936-2000.cnv
  windows-950-2000.cnv
  # base tables the two extension converters above depend on
  ibm-1386_P100-2001.cnv
  ibm-1373_P100-2002.cnv
)

cd "${WORK}"
printf '%s\n' "${ITEMS[@]}" > items.txt
# Extract the items from the full package...
mkdir -p extracted
icupkg -x items.txt -d extracted "${SRC}"
# ...and pack them into a new package. The package name must be "icudt68l"
# because ICU looks items up as "icudt68l/<item>".
icupkg -tl -a items.txt -s extracted new icudt68l.dat
icupkg -l icudt68l.dat

python3 - icudt68l.dat "${OUT}/icudata_subset.c" <<'EOF'
import sys
data = open(sys.argv[1], 'rb').read()
with open(sys.argv[2], 'w') as f:
    f.write('/* Generated by icu/make-icudata.sh: filtered ICU 68.2 data (%d bytes). */\n' % len(data))
    f.write('/* ICU data is Unicode-DFS-2016 licensed (see README). */\n')
    f.write('#include <stdalign.h>\n')
    f.write('alignas(16) const unsigned char oi_icudata_subset[%d] = {\n' % len(data))
    for i in range(0, len(data), 16):
        f.write('  ' + ','.join(str(b) for b in data[i:i + 16]) + ',\n')
    f.write('};\n')
    f.write('const unsigned long oi_icudata_subset_size = %d;\n' % len(data))
print("icudata_subset.c:", len(data), "bytes of ICU data")
EOF
ls -l "${OUT}"