make-json-files

#!/usr/bin/env bash
set -euo pipefail

# This is invoked as part of the site deployment, whenever stable channel
# versions are bumped, and converts synadia-nats-channels.conf into other files
# in JSON format.
# The .sh installer is not allowed to rely upon JSON handling being available,
# and the core config supports that, but other installers should get something
# saner.
#
# This script was written in bash, because as a superset of POSIX sh it let me
# copy/paste the config extraction and templating functions I'd written and quickly
# massage data with jq.  But any shell is not an ideal choice and this script is
# a candidate for being rewritten to another language.  The initial development
# expediency has given us something which runs "within a couple of seconds"
# (instead of milliseconds) but which requires comfort with sh+jq which might
# become a maintenance headache for others.

progname="$(basename "$0" .sh)"
note() { printf >&2 '%s: %s\n' "$progname" "$*"; }
die() { note "$@"; exit 1; }

readonly DEPLOY_DIR="${1:-public}"
readonly SH_CHANNELS_FILE=synadia-nats-channels.conf
readonly NIGHTLY_DATE_URL='https://get-nats.io/current-nightly'

# These are the two files we make.
# The first is a straight reformatting of the .conf to JSON, still requiring expansion.
# The second is a system keyed by platform.
readonly OUT_CHANNELS="$DEPLOY_DIR/synadia-nats-channels.json"
readonly OUT_PLATFORMS="$DEPLOY_DIR/synadia-nats-platforms.json"

readonly -a SUPPORTED_PLATFORMS=(
      darwin-amd64
      darwin-arm64
      freebsd-amd64
      linux-386
      linux-amd64
      linux-arm64
      linux-arm6
      linux-arm7
      windows-386
      windows-amd64
      windows-arm64
      windows-arm6
      windows-arm7
)
readonly -A PLATFORM_EXE_EXTENSION=(
      [windows-arm6]='exe'
      [windows-arm64]='exe'
)

# --------------------------8< End of Config >8---------------------------

# Defining this lets us use grab_channelfile_line unmodified from install.sh
chanfile="$SH_CHANNELS_FILE"
chan_origin="$SH_CHANNELS_FILE"

command -v jq >/dev/null || die "missing command: jq"

# From: install.sh {{{

grab_channelfile_line() {
  local varname="${1:?need a file to get from the channel file}"
  local t
  # sed -E is not POSIX, so we're on BREs only
  t="$(sed -n "s/${varname}[[:space:]]*=[[:space:]]*//p" < "${chanfile:?bug, chanfile not in calling context}")"
  if [ -n "$t" ]; then
    printf '%s\n' "$t"
  else
    die "missing '${varname}' in ${chan_origin:?}"
  fi
}

expand_config_value() {
  local val="$1"
  local subst="$2"
  local replace="$3"
  local result=""
  while [ "$val" != "${val#*\%${subst}\%}" ]; do
    pre="${val%%\%${subst}\%*}"
    post="${val#*\%${subst}\%}"
    result="${result}${pre}${replace}"
    val="$post"
  done
  result="${result}${val}"
  printf '%s\n' "$result"
}

# From: install.sh }}}

expand_all() {
  local val="$1"
  shift
  local tag lhs rhs
  for tag; do
    lhs="${tag%%:*}"
    rhs="${tag#*:}"
    val="$(expand_config_value "$val" "$lhs" "$rhs")"
  done
  printf '%s\n' "$val"
}

declare -a all_channels=() all_tools=() expansions=() platform_expands=() tool_jq=()

note "Building data (slowly, can be rewritten to Python to be faster)"

all_channels+=($(grab_channelfile_line CHANNELS))
all_tools+=($(grab_channelfile_line TOOLS))

# jchdata goes into synadia-nats-channels.json
jchdata='{}'
# jplatformdata goes into synadia-nats-platforms.json
jplatformdata='{}'

for channel in "${all_channels[@]}"; do
  jchannel='{}'
  case "$channel" in
    nightly)
      jchannel="$(jq <<<"$jchannel" --arg U "$NIGHTLY_DATE_URL" '.version_url = $U')"
      ;;
  esac
  jexpanded_channel="$(jq <<<"$jchannel" --arg C "$channel" '.platforms = {}')"

  for tool in "${all_tools[@]}"; do
    suffix="${channel}_${tool}"
    version='' zipfile='' checksumfile='' urldir='' executable='' jtool='' tool_object=''

    zipfile="$(grab_channelfile_line "ZIPFILE_${suffix}")"
    checksumfile="$(grab_channelfile_line "CHECKSUMS_${suffix}")"
    urldir="$(grab_channelfile_line "URLDIR_${suffix}")"
    jtool="$(jq -nr --arg Z "$zipfile" --arg C "$checksumfile" --arg U "$urldir" '.zipfile = $Z | .checksumfile = $C | .urldir = $U')"

    # Directives used to invoke expand_all:
    expansions=( "TOOLNAME:$tool" "ZIPFILE:$zipfile" "CHECKFILE:$checksumfile")
    # See jexpanded_channel below in the platform loop (for synadia-nats-platforms.json):
    tool_jq=( --arg T "$tool" )
    tool_object='executable: $E, zip_url: $Z, checksum_url: $C'

    case "$channel" in
      nightly)
        expansions+=( "VERSIONTAG:%NIGHTLY%" "VERSIONNOV:%NIGHTLY%" )
        ;;
      *)
        version="$(grab_channelfile_line "VERSION_${suffix}")"
        jtool="$(jq <<<"$jtool" --arg V "$version" '.version = $V')"
        expansions+=( "VERSIONTAG:$version" "VERSIONNOV:${version#v}" )
        tool_jq+=( --arg VT "$version" --arg VB "${version#v}" )
        tool_object="${tool_object}"', version_tag: $VT, version_bare: $VB'
        ;;
    esac

    jchannel="$(jq <<<"$jchannel" --arg T "$tool" --argjson P "$jtool" '.[$T] = $P')"

    for platform in "${SUPPORTED_PLATFORMS[@]}"; do
      executable="$tool${PLATFORM_EXE_EXTENSION[$platform]:+.}${PLATFORM_EXE_EXTENSION[$platform]:-}"
      jexpanded_channel="$(jq <<<"$jexpanded_channel" --arg P "$platform" '.platforms[$P] //= {tools: {}}')"
      platform_expands=( "${expansions[@]}" "OSNAME:${platform%%-*}" "GOARCH:${platform#*-}" )

      zip_url="$(expand_all "${urldir}${zipfile}" "${platform_expands[@]}")"
      chk_url="$(expand_all "${urldir}${checksumfile}" "${platform_expands[@]}")"
      jexpanded_channel="$(jq <<<"$jexpanded_channel" \
        "${tool_jq[@]}" --arg P "$platform" --arg Z "$zip_url" --arg C "$chk_url" --arg E "$executable" \
        '.platforms[$P].tools[$T] = '"{ $tool_object }")"
    done

  done

  jchdata="$(jq <<<"$jchdata" --arg C "$channel" --argjson P "$jchannel" '.[$C] = $P')"
  jplatformdata="$(jq <<<"$jplatformdata" --arg C "$channel" --argjson P "$jexpanded_channel" '.[$C] = $P')"
done

[[ -d "$DEPLOY_DIR" ]] || mkdir -pv -- "$DEPLOY_DIR"
note "Writing: $OUT_CHANNELS"
printf '%s\n' > "$OUT_CHANNELS" "$jchdata"
note "Writing: $OUT_PLATFORMS"
printf '%s\n' > "$OUT_PLATFORMS" "$jplatformdata"