yglu-overlay

#!/bin/bash

# Helper for yglu to assist with importing yaml files into the document
# root.
#
# Depends: yglu - https://github.com/lbovet/yglu/
#
# Copyright (c) 2020-2021 Maddison Hellstrom <github.com/b0o>, MIT License.

set -euo pipefail

declare base basename

base="$(realpath "${BASH_SOURCE[0]}")"
basename="$(basename "$base")"

declare -ga tmpfiles=()

declare -gi merge_lists=0

function usage() {
  echo "usage: $basename [-h] [[<template> <dest>] ...]" >&2
}

function process_template() {
  [[ $# -lt 2 ]] && {
    echo "process_template: expected 2 args, got $#" >&2
    return 1
  }

  local template="$1"
  local dest="$2"

  local tmp_template
  local tmp_dest
  tmp_template="$(mktemp "$(basename "$template")-XXXXXX")" || {
    echo "error making temp file" >&2
    return 1
  }
  tmpfiles+=("$tmp_template")
  tmp_dest="$(mktemp "$(basename "$template")-XXXXXX")" || {
    echo "error making temp file" >&2
    return 1
  }
  tmpfiles+=("$tmp_dest")

  local -a yglu_import
  mapfile -t yglu_import << "EOF"
# Merge imports with each other
# primitives, lists: replace, later take precedence
# dicts:             merge, contained primitives and lists handled as above
_imported: !-
  !for ($_._import)({}): !()
    !for $.items(): !()
EOF

  if [[ $merge_lists -eq 1 ]]; then
    mapfile -tO ${#yglu_import[@]} yglu_import << "EOF"
      !? $[0]: !? ({result => $[1]}).mergeWith({result => $_._imported.get($[0], null)}, $2 + $1, $1).get("result", null)
EOF
  else
    mapfile -tO ${#yglu_import[@]} yglu_import << "EOF"
      !if isDict($[1]):
        !? $[0]: !? ({result => $[1]}).mergeWith({result => $_._imported.get($[0], null)}, $1, $1).get("result", null)
      !if not isDict($[1]):
        !? $[0]: !? $[1]
EOF
  fi

  mapfile -tO ${#yglu_import[@]} yglu_import << "EOF"
# Merge aggregated imports with document root
# primitives, lists: values in document root take precedence
# dicts:             merge, values in document root take precedence, contained primitives and lists handled as above
!for $_._imported.items(): !()
  !if $_.get($[0], null) = null:
    !? $[0]: !? $[1]
  !if $_.get($[0], null) != null:
    !if not ($_.containsKey("_merge_skip") and $_._merge_skip.toList().contains($[0])):
EOF

  if [[ $merge_lists -eq 1 ]]; then
    mapfile -tO ${#yglu_import[@]} yglu_import << "EOF"
      !? $[0]: !? ({result => $_.get($[0], null)}).mergeWith({result => $[1]}, $2 + $1, $1).get("result", null)
EOF
  else
    mapfile -tO ${#yglu_import[@]} yglu_import << "EOF"
    !if isDict($[1]):
      !? $[0]: !? ({result => $_.get($[0], null)}).mergeWith({result => $[1]}, $1, $1).get("result", null)
EOF
  fi

  awk -v "import=$(printf '%s\n' "${yglu_import[@]}")" \
    '/^_import:\s+!\(\)\s*$/ { print import "\n" }; //{ print $0 }' "$1" \
    > "$tmp_template"

  yglu "$tmp_template" > "$tmp_dest" || {
    echo "yglu failed" >&2
    return 1
  }

  cat "$tmp_dest" > "$dest"
  return
}

function main() {
  local -a templates=()
  local -a dests=()

  local opts_ok=1

  while [[ $# -gt 0 ]]; do
    [[ "$1" =~ ^- ]] && {
      [[ $opts_ok -eq 0 ]] && {
        echo "unexpected option $1" >&2
        usage
        exit 1
      }
      case "$1" in
      -h | --help)
        usage
        exit 0
        ;;
      --merge-lists)
        merge_lists=1
        ;;
      *)
        echo "unknown option $1" >&2
        usage
        exit 1
        ;;
      esac
      shift
      continue
    }
    opts_ok=0
    if [[ ${#templates[@]} -eq ${#dests[@]} ]]; then
      templates+=("$1")
    else
      dests+=("$1")
    fi
    shift
  done

  [[ ${#templates[@]} -ne ${#dests[@]} ]] && {
    usage
    exit 1
  }

  [[ ${#templates[@]} -eq 0 && ${#dests[@]} -eq 0 ]] && {
    mapfile -t templates <<< "$(find . -maxdepth 1 -type f -name '*.yglu.yml' -printf '%f\n')"
    dests=("${templates[@]/%.yglu.yml/.yml}")
  }

  for ((i = 0; i < ${#templates[@]}; i++)); do
    local t="${templates[$i]}"
    local d="${dests[$i]}"
    echo "$t -> $d" >&2
    process_template "$t" "$d"
  done
}

trap 'rm "${tmpfiles[@]}" 2>/dev/null || true' EXIT

main "$@"