# syntax=docker/dockerfile:1
#
# helpdeco (the WinHelp decompiler by Manfred Winterhoff, Ben Collver and Paul
# Wise, GPL) compiled to WebAssembly for johnmcm.com's /hlp-viewer: it turns a
# .hlp into RTF topics, a project file and pictures. It is built unmodified, as
# a program: each run is a fresh instance with its own in-memory file system.
# (The page decodes helpdeco's SHG and MRB pictures itself; the package's
# splitmrb writes them out garbled when built for 32 bits.) The Emscripten image is
# pinned by version and digest, helpdeco by commit; the source built is
# copied into source/ and published with these files at /source/helpdeco/.
#
#   ./build.ps1     (or)   docker build --target export --output type=local,dest=dist .

ARG EMSDK_IMAGE=emscripten/emsdk:6.0.10@sha256:e077d54e2b8970575ebc4f185ac1de0b95c05f2b266134d4ba27449af7aebf65
FROM ${EMSDK_IMAGE} AS build

ARG HELPDECO_COMMIT=785273788af17fde4fba7df7162d547f8645d7d8
RUN git clone -q https://github.com/pmachapman/helpdeco /helpdeco \
 && git -C /helpdeco checkout -q ${HELPDECO_COMMIT} \
 && test "$(git -C /helpdeco rev-parse HEAD)" = "${HELPDECO_COMMIT}"

# Common settings: a program run by callMain, stdin supplied by the page (helpdeco
# asks "Press CR to continue" after recoverable damage; the page always answers yes).
ARG EMFLAGS="-O2 -w -sMODULARIZE=1 -sEXPORT_ES6=1 -sENVIRONMENT=worker,node \
  -sINVOKE_RUN=0 -sEXIT_RUNTIME=1 -sALLOW_MEMORY_GROWTH=1 -sMAXIMUM_MEMORY=2147483648 \
  -sSTACK_SIZE=1048576 -sDYNAMIC_EXECUTION=0 -sFORCE_FILESYSTEM=1 \
  -sINCOMING_MODULE_JS_API=print,printErr,stdin,locateFile,wasmBinary,instantiateWasm \
  -sEXPORTED_RUNTIME_METHODS=callMain,FS"

RUN mkdir -p /out/source \
 && cd /helpdeco/src \
 && cp helpdeco.c helpdec1.c helpdeco.h compat.c compat.h helper.h /helpdeco/LICENSE /helpdeco/README /out/source/ \
 && emcc ${EMFLAGS} -sEXPORT_NAME=createHelpdeco helpdeco.c helpdec1.c compat.c -o /out/helpdeco.mjs

FROM scratch AS export
COPY --from=build /out/ /