scripts: add release/dump-version-info.sh (#309)

I used this script to help me orient myself.

I think it might be possible to use it to simplify the other CI and/or
release scripts that are related.

Author: nfrisby

scripts/release/dump-version-info.sh

@@ -0,0 +1,116 @@
+#!/usr/bin/env bash
+
+set -eu
+
+# Emit a JSON object in which each property is a package name and its value is
+# an object whose properties are the version (as a string) from its cabal file,
+# the latest version (as a string) from its `CHANGELOG.md' file, and the names
+# of the files other than `scriv.ini' in its `changelog.d' directory.
+#
+# There are two assumptions made. First, every `scriv.ini' file is at depth 3
+# in the git repository. Second, each `${GITROOT}/X/changelog.d/scriv.ini' file
+# has matching `${GITROOT}/X/X.cabal' and `${GITROOT}/X/CHANGELOG.md' files,
+# such that the cabal package name is also `X'.
+
+# See https://stackoverflow.com/a/3352015
+function trim {
+    local var="$*"
+    # remove leading whitespace characters
+    var="${var#"${var%%[![:space:]]*}"}"
+    # remove trailing whitespace characters
+    var="${var%"${var##*[![:space:]]}"}"
+    printf '%s' "$var"
+}
+
+function project_cabal_file_version {
+    trim "$(grep -E -e '^version:' | head -n1 | cut -d':' -f2-)"
+}
+
+function project_latest_changelog_version {
+    trim "$(grep -E -e '^## ' | head -n1 | awk '{print $2}')"
+}
+
+function normalize_changelog.d_filenames {
+    grep -vE -e '^scriv.ini$' | sort
+}
+
+function WORKINGTREE_package {
+    pkg="$(basename "$1")"
+    echo "\"$pkg\": {"
+
+    echo -n '"version": "'
+    cat "$1/$pkg.cabal" | project_cabal_file_version
+    echo '",'
+
+    echo -n '"changelog-version": "'
+    cat "$1/CHANGELOG.md" | project_latest_changelog_version
+    echo '",'
+
+    echo -n '"changelog.d-files": '
+    echo -n '['
+    local comma=0
+    (cd "$1/changelog.d/"; ls -A1) | normalize_changelog.d_filenames | while read -r line; do
+        [[ $((comma++)) -gt 0 ]] && echo -n ','
+        echo -n "\"$line\""
+    done
+    echo ']'
+
+    echo '}'
+}
+
+function GITREV_package {
+    echo "\"$2\": {"
+
+    echo -n '"version": "'
+    git show "$1:$2/$2.cabal" | project_cabal_file_version
+    echo '",'
+
+    echo -n '"changelog-version": "'
+    git show "$1:$2/CHANGELOG.md" | project_latest_changelog_version
+    echo '",'
+
+    echo -n '"changelog.d-files": '
+    echo -n '['
+    local comma=0
+    basename -a $(git ls-tree --name-only "$1" --full-tree -- "$2/changelog.d/") | normalize_changelog.d_filenames | while read -r line; do
+        [[ $((comma++)) -gt 0 ]] && echo -n ','
+        echo -n "\"$line\""
+    done
+    echo ']'
+
+    echo '}'
+}
+
+function WORKINGTREE_case {
+    local comma=0
+    find "$(git rev-parse --show-toplevel)" -maxdepth 3 -type f -name 'scriv.ini' | sort | while read -r path; do
+        [[ $((comma++)) -gt 0 ]] && echo -n ','
+        WORKINGTREE_package "$(realpath "$(dirname "$path")/..")"
+    done
+}
+
+function GITREV_case {
+    local comma=0
+    # `sort' behaves differently if the trailing slash is present or not, and
+    # it will be present in the `WORKINGTREE_case', so synthetically add it
+    # here.
+    git ls-tree --name-only "$1" --full-tree | sed -r 's|$|/|' | sort | while read -r dir; do
+        dir="$(basename "$dir")"   # remove the trailing slash
+        for i in $(git ls-tree --name-only "$1" --full-tree -- "$dir/changelog.d"); do
+            [[ $((comma++)) -gt 0 ]] && echo -n ','
+            GITREV_package "$1" "$dir"
+        done
+    done
+}
+
+function main {
+    echo '{'
+    if [ $# -eq 0 ]; then
+        WORKINGTREE_case
+    else
+        GITREV_case "$1"
+    fi
+    echo '}'
+}
+
+main "$@"