#!/usr/bin/env sh
#
# What version an artifact carries, derived from its OWN shipped files.
#
# Replaces desktop/packaging/build-version.sh, which was one generator feeding the
# desktop bundles AND the Android APK off `GITHUB_RUN_NUMBER`. A Kotlin-only commit
# re-versioned the desktop; a Rust-only commit re-versioned the phone. It read as
# tidy — one definition, no drift — which is exactly why it survived review. One
# definition of HOW to derive is right; one VALUE for unrelated artifacts is not.
# (Note 3127 §3, which cites this repo as its example of the failure.)
#
# Lives at the repo root, not under desktop/, because it now serves three artifacts
# and a shared thing filed under one consumer is how it ends up owned by that one.
#
#   version.sh display <artifact>   the human-readable version — 2026.08.28.1815
#   version.sh key     <artifact>   the ordering key a comparator reads
#   version.sh paths   <artifact>   the shipped file set (for tests and debugging)
#
# TWO VALUES, NOT ONE, and which you want depends on the question:
#
#   "is this the same code?"        -> display. A dev build and the main build of one
#                                     commit read identically, because they ARE the
#                                     same bytes (note 3127 §2, reason 4).
#   "may this replace that?"        -> key. What an updater or an install gate
#                                     compares, and never shown to a person.
#
# The desktop needs both because Tauri's updater parses `latest.json`'s version with
# the semver crate, and `2026.08.28.1815` is not valid semver — four segments where
# the spec allows three, and `08` is a leading zero, which it forbids outright. A
# non-semver string does not sort low: the feed fails to DESERIALIZE and every client
# reports "no update available" forever. So the platform's field takes an opaque key
# and the display version lives beside it. See #3142's spike.
#
# WHY NOT A `-dev.N` PRERELEASE for the dev channel — carried over from the script
# this replaces, because it is a real finding and the reasoning is not obvious:
# a prerelease sorts BELOW the release it qualifies (`0.1.0-dev.5` < `0.1.0`), so a
# dev build could never be offered as an update to a tagged one, and Windows
# installer metadata wants a numeric X.Y.Z anyway. The channel goes in a sibling
# field, never in the version — note 3127 §7, and rule 149.
set -eu

# ANCHOR AT THE REPO ROOT BEFORE ANYTHING ELSE.
#
# `git log -- <paths>` resolves pathspecs relative to the CURRENT DIRECTORY, not to
# the repo root. Callers run from wherever suits them — the desktop build from
# `desktop/src-tauri`, the Android build from `android`, the manifest job from the
# root — so without this the same request answers differently per caller.
#
# It is not a tidy failure. Measured on run 4796, one push produced THREE versions:
# the desktop build (cwd `desktop/src-tauri`) said 1.0.3494522, while the pacman
# packager and the manifest job both said 1.0.3502131. The build's pathspec had
# matched `desktop/src-tauri/Cargo.toml` — a real file — so git returned the newest
# commit touching THAT, six days stale. Non-empty, so the guard below could not fire;
# the manifest then found no bundle matching its own answer and the lane went red for
# a reason two steps removed from the cause.
#
# The Android job failed loudly in the same run only because its pathspec happened to
# match nothing from `android/`. Same bug, louder symptom, pure luck.
cd "$(git rev-parse --show-toplevel)"

# 2020-01-01T00:00:00Z. The counter epoch, and it must NEVER move: shifting it
# renumbers every artifact downwards, which is the one direction you cannot recover
# from (note 3127 §6.4).
EPOCH=1577836800

# --- the shipped file sets ---------------------------------------------------
#
# ONE definition, read by every consumer. The `paths:` filters in the three
# workflows are a second, independent statement of the same fact today; they come
# out in step 6 when skip-if-exists replaces them. Until then, a change here that is
# not mirrored there means a lane that does not fire — check both.
#
# Read off what actually PACKAGES each artifact, not off intuition. Miss a file and
# a stale build keeps its version; include one that does not ship and you re-version
# for nothing.
#
# THE BUILD DEFINITION IS IN THE SET, and it is the part that is easy to leave out.
# A workflow file is not "shipped" — but change a Gradle flag or a `cargo tauri
# build` argument and the bytes change while the source does not. Once step 6 skips
# a build whose version already exists, that combination serves the OLD artifact on
# a green run: exactly the "miss a file and a stale build keeps its version" failure,
# arriving through the build recipe rather than the source. Same reason `packaging/`
# is in every set: this script decides identity, so a change to it is a change to
# what each artifact claims to be.
paths_for() {
  case "$1" in
    # tauri's generate_context! embeds the BUILT frontend in the binary, so a
    # frontend commit is a desktop change even though nothing under desktop/ moved.
    desktop) echo "desktop core frontend Cargo.toml Cargo.lock .forgejo/workflows/desktop.yml packaging" ;;
    # The .so is cross-compiled from core/ through uniffi.
    android) echo "android core Cargo.toml Cargo.lock .forgejo/workflows/android.yml packaging" ;;
    # BUNDLED ARTIFACT: the image bakes in the Android client (ci.yml fetches the APK
    # from the channel release and copies it into the package). So the image's set
    # must contain the APK's set — an APK-only change genuinely changes what this
    # image ships. Note 3127 §3 names this trap; FC's web image embeds the extension
    # the same way.
    #
    # The base images are NOT listed and do not need to be: `Dockerfile` is in the
    # set, so pinning `FROM` by digest (step 6) puts the base inside the set for
    # free. Resolving a digest at derive time would work too and is WRONG — it is an
    # external lookup, which §7's corollary forbids because it makes the value depend
    # on when it was computed.
    server)  echo "src frontend alembic alembic.ini Dockerfile pyproject.toml .forgejo/workflows/ci.yml android core Cargo.toml Cargo.lock .forgejo/workflows/android.yml packaging" ;;
    *) echo "version.sh: unknown artifact '$1'" >&2; exit 2 ;;
  esac
}

# Sets TS to the newest commit timestamp touching this artifact's files, or exits.
#
# EMPTY IS FATAL, deliberately. A shallow clone sees one commit and derives a
# too-low value with every lane green — the failure landmine §6.1 exists for, and
# the unrecoverable direction. Every job that calls this needs `fetch-depth: 0`;
# this is what turns forgetting it into a red lane instead of a stranded channel.
#
# SETS A GLOBAL RATHER THAN ECHOING, and that is not a style preference. Written as
# `$(commit_ts desktop)` the function runs in a SUBSHELL, so its `exit` ends only
# that subshell and the caller continues with an empty string. Measured before this
# was fixed: `key desktop` on a repo with no matching history printed the error to
# stderr and then emitted `1.0.-26297280` and exited ZERO. A guard that reports a
# problem and does not stop is worse than none — it looks like it is working.
resolve_ts() {
  # Unquoted on purpose: the path list is several words.
  # shellcheck disable=SC2046
  TS="$(git log --format=%ct -1 HEAD -- $(paths_for "$1"))"
  if [ -z "$TS" ]; then
    echo "version.sh: no commit touches $1's file set — is this a shallow clone?" >&2
    echo "            (needs fetch-depth: 0; see note 3127 §6.1)" >&2
    exit 1
  fi
}

minutes_since_epoch() { echo $(( ($1 - EPOCH) / 60 )); }

what="${1:?usage: version.sh <display|key|paths> <desktop|android|server>}"
artifact="${2:?usage: version.sh <display|key|paths> <desktop|android|server>}"

# VALIDATED HERE, in the parent shell, and not left to `paths_for`'s default arm.
#
# Third instance of one trap in this script, so it is worth stating plainly: `exit`
# inside a function called as `$(...)` ends the SUBSHELL, not the script. `paths_for`
# is reached through `$(paths_for "$1")`, so its `exit 2` printed the error and
# returned an EMPTY pathspec — and an empty pathspec matches everything, so
# `version.sh display nope` answered `2026.08.28.0900` and exited 0. A confident
# version for an artifact that does not exist.
#
# The other two were the shallow-clone guard on the `key` path (emitted
# `1.0.-26297280`, exit 0) and the same guard on `display` (which failed only because
# `date` then choked on an empty string — luck, not design). Each was found by a
# different mechanism; none by reading the code. If you add a guard to this file,
# make sure it runs where the script does.
case "$artifact" in
  desktop|android|server) : ;;
  *)
    echo "version.sh: unknown artifact '$artifact' (want desktop, android or server)" >&2
    exit 2
    ;;
esac

case "$what" in
  paths)
    paths_for "$artifact"
    ;;

  display)
    # One shape for every human-readable version in this repo, and for the release
    # tag: YYYY.MM.DD.HHMM, zero-padded, UTC (note 3127 §1). Padded so it sorts as
    # text as well as numerically, and so two lanes cannot emit forms one character
    # apart.
    resolve_ts "$artifact"
    date -u -d "@$TS" +%Y.%m.%d.%H%M
    ;;

  key)
    case "$artifact" in
      desktop)
        # COMMIT time. The desktop is a one-value system to Tauri — its comparator
        # reads the version name — so this key is also what lands in bundle
        # filenames and .deb metadata. Commit time buys the property in §2 reason
        # (4): the last dev build before a PR and the main build from it are the
        # same bytes and derive the same key, so the artifact is reused rather than
        # rebuilt and re-signed under a new name.
        #
        # Commit time CAN go backwards (rebuild an older commit). The backwards
        # guard in step 5 is the whole mitigation, and the desktop's failure there
        # is soft: an update is not offered. Contrast Android below.
        #
        # `1.0.` and not `0.0.`: the minor must clear the installed `0.2.<run>` line
        # or every dev user is stranded on "up to date" permanently. Checked against
        # the live feed (0.2.466), not against what we thought we had published.
        resolve_ts desktop
        echo "1.0.$(minutes_since_epoch "$TS")"
        ;;
      android)
        # BUILD time, and the asymmetry with the desktop is deliberate. Android
        # HARD-FAILS an install on a downgrade (INSTALL_FAILED_VERSION_DOWNGRADE)
        # and leaves a channel you cannot get out of, so its key must be monotonic
        # BY CONSTRUCTION rather than by a guard that runs in CI. Build time cannot
        # go backwards; commit time can.
        #
        # An Int, which is what Android compares. ~3.5M today against a 2.1e9
        # ceiling — roughly four thousand years of headroom.
        minutes_since_epoch "$(date -u +%s)"
        ;;
      server)
        # NO ORDERING KEY. Nothing compares the server image: no updater, no install
        # gate, and `:latest` is moved by the registry rather than chosen by a
        # client. §2 is explicit that an artifact with nothing to compare needs only
        # a name — do not add one because the other two have one.
        echo "version.sh: the server has no ordering key; use 'display'" >&2
        exit 2
        ;;
      *) echo "version.sh: unknown artifact '$artifact'" >&2; exit 2 ;;
    esac
    ;;

  *)
    echo "version.sh: unknown request '$what' (want display, key or paths)" >&2
    exit 2
    ;;
esac