From 717391d835fc7af8a9a18138c39e1a17e82b9210 Mon Sep 17 00:00:00 2001
From: David Boreham <david@bozemanpass.com>
Date: Mon, 19 Dec 2022 09:37:24 -0700
Subject: [PATCH] Add comments

---
 .../cerc-builder-js/yarn-local-registry-fixup.sh       | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/container-build/cerc-builder-js/yarn-local-registry-fixup.sh b/container-build/cerc-builder-js/yarn-local-registry-fixup.sh
index b16585cf..db04c433 100755
--- a/container-build/cerc-builder-js/yarn-local-registry-fixup.sh
+++ b/container-build/cerc-builder-js/yarn-local-registry-fixup.sh
@@ -1,6 +1,12 @@
 #!/bin/bash
 # Usage: yarn-local-registry-fixup.sh <package-to-fix>
 # Assumes package.json and yarn.lock are in the cwd
+# The purpose of this script is to take a project cloned from git
+# and "fixup" its yarn.lock file such that specified dependency
+# will be fetched from a repository other than the one used when
+# yarn.lock was generated. It updates all checksums using data
+# from the "new" registry (because due to embedded timestamps etc
+# the same source code re-built later will not have the same checksum).
 if [ -n "$CERC_SCRIPT_DEBUG" ]; then
     set -x
 fi
@@ -10,11 +16,14 @@ if [[ $# -ne 1 ]]; then
 fi
 target_package=$1
 versioned_target_package=$(grep ${target_package} package.json | sed -e 's#[[:space:]]\{1,\}\"\('${target_package}'\)\":[[:space:]]\{1,\}\"\(.*\)\",#\1@\2#' )
+# Use yarn info to get URL checksums etc from the new registry
 yarn_info_output=$(yarn info --json $versioned_target_package 2>/dev/null)
+# Code below parses out the values we need
 package_tarball=$(echo $yarn_info_output | jq -r .data.dist.tarball)
 package_integrity=$(echo $yarn_info_output | jq -r .data.dist.integrity)
 package_shasum=$(echo $yarn_info_output | jq -r .data.dist.shasum)
 package_resolved=${package_tarball}#${package_shasum}
+# Some strings need to be escaped so they work when passed to sed later
 escaped_package_resolved=$(printf '%s\n' "$package_resolved" | sed -e 's/[\/&]/\\&/g')
 escaped_target_package=$(printf '%s\n' "$target_package" | sed -e 's/[\/&]/\\&/g')
 if [ -n "$CERC_SCRIPT_VERBOSE" ]; then
@@ -23,5 +32,6 @@ if [ -n "$CERC_SCRIPT_VERBOSE" ]; then
     echo "Shasum: ${package_shasum}"
     echo "Resolved: ${package_resolved}"
 fi
+# Use magic sed regex to replace the values in yarn.lock
 sed -i -e '/^\"'${escaped_target_package}'.*\":$/ , /^\".*$/ s/^\([[:space:]]\{1,\}resolved \).*$/\1'\"${escaped_package_resolved}\"'/' yarn.lock
 sed -i -e '/^\"'${escaped_target_package}'.*\":$/ , /^\".*$/ s/^\([[:space:]]\{1,\}integrity \).*$/\1'${package_integrity}'/' yarn.lock