#!/usr/bin/env sh
#
# The markdown body for a release: what went live since the previous one.
#
#   release-notes.sh <tag>
#
# A release BUILDS NOTHING now (M314 step 7). The merge to `main` already published
# `:latest`, `:<sha>` and both channel feeds, so a tag rebuilding that same source
# would produce identical artifacts and re-push `:<sha>` with different bytes —
# which rule 145 forbids even when the bytes match.
#
# So what is a release FOR? Note 3127 §5 answers it: the changelog. There are two
# halves to "what am I running" and the version answers only the first —
#
#   which build is this          the footer, /api/config, the APK's versionName
#   what is in it that was not    ← this
#     in the one I ran last month
#
# DERIVED FROM GIT, not hand-maintained. A CHANGELOG.md drifts into being
# aspirational — it records what someone meant to ship. `git log` records what
# shipped, and cannot say otherwise.
set -eu

cd "$(git rev-parse --show-toplevel)"

tag="${1:?usage: release-notes.sh <tag>}"

# The previous release tag, by DATE rather than by name.
#
# `v*` only: this repo also carries `dev` and `stable` tags, which are the fixed-tag
# pointer releases the updater reads. They move constantly and are not releases in
# this sense; sorting them in would make "the previous release" mean whichever
# channel published most recently.
#
# Excludes the tag being described, so re-running on an existing tag still produces
# the range that tag covers rather than an empty one.
prev="$(git tag -l 'v*' --sort=-creatordate | grep -vxF "$tag" | head -1 || true)"

if [ -n "$prev" ]; then
  range="$prev..$tag"
  header="Changes since \`$prev\`."
else
  # The first release. Everything is new, and listing the entire history would be
  # noise — say so instead.
  range="$tag"
  header="First release."
fi

printf 'ThoughtSync %s\n\n%s\n\n' "$tag" "$header"

# `--no-merges`: a merge commit's subject is "Merge branch ..." and says nothing
# about what shipped. The commits it brought in are listed individually, which is
# what somebody reading this wants.
#
# `%s` alone, not `%s (%h)`: the sha is in the forge's own view of the release and
# a reader chasing a specific change clicks through rather than copying a hash out
# of prose.
# CAPPED, because an unbounded list is not a changelog — it is a wall.
#
# The first dated release spans everything since `v0.1.0` — 181 commits at the
# time of writing: nobody reads that, and burying twelve interesting changes in it is worse
# than not writing one. Later releases will be short and the cap will never bite.
#
# The most RECENT are kept, not the oldest, and the count of what was dropped is
# stated — a truncated list that does not say it is truncated is a lie.
CAP=60
total="$(git log --no-merges --format='%s' "$range" | wc -l | tr -d ' ')"

git log --no-merges --reverse --format='- %s' "$range" | tail -"$CAP"

if [ "$total" -gt "$CAP" ]; then
  printf '\n_...and %s earlier commits in this range, omitted for length._\n' \
    "$((total - CAP))"
fi

printf '\n'
printf '%s\n' "_No artifacts here. Builds reach users from \`main\`: the desktop and Android"
printf '%s\n' "channels and the server image all publish on merge, with no tag required. This"
printf '%s\n' "release is a bookmark — it names a moment and says what was in it._"