#!/bin/bash
# THE RELEASE GATE: may this exact file go to a classroom?
#
#   tools/release-gate.sh PACKAGE.deb [FROM_VERSION...]
#   tools/release-gate.sh --ci PACKAGE.deb           for CI; see below
#   tools/release-gate.sh --still-current REPORT PACKAGE.deb
#
# Runs tools/validate-trixie-release.sh against PACKAGE as
#
#   * a fresh install;
#   * an upgrade from what canary serves today, on a canary room;
#   * an upgrade from what stable serves today, on a stable room;
#   * an upgrade from each FROM_VERSION, on a stable room — the release a
#     room is really still on, which can be several behind stable.
#
# The releases it upgrades from are downloaded over HTTPS the way a
# classroom downloads them, and each is checked against the SHA-256 its
# manifest publishes, or, for a FROM_VERSION, against the version dpkg
# reads out of it. Nothing here needs a credential or writes to the
# update server, so a CI runner can run it on code nobody has reviewed.
#
# Every run is one line in RELEASE_GATE_REPORT (default: printed only),
# so the result can be attached to the release it describes.
#
# It stops at the first failure: a gate that carries on reports a pass
# for a machine it never finished building.
#
# --ci is for a commit, not a release. Between releases master's VERSION
# is what canary already serves, and no room can upgrade to a version it
# has; such an upgrade is recorded as SKIP, with why, instead of failing
# every commit. Its report says it is a CI report and can never stand in
# for a release's.
#
# --still-current REPORT PACKAGE asks whether a gate report may still be
# relied on to publish PACKAGE: it has to be a release gate's report, for
# exactly these bytes, that passed, and whose upgrades were from exactly
# what canary and stable serve now. A report made before either channel
# moved is not current, and the gate has to be run again. Exit 0 or 1.
set -euo pipefail
# The fetches below run in $(...), which otherwise ignores set -e: a
# manifest that failed to download would go on to compare an empty hash
# with an empty hash, and match.
shopt -s inherit_errexit

ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
source "$ROOT/tools/release-lib.sh"

usage() {
    echo "Usage: $0 [--ci] PACKAGE.deb [FROM_VERSION...]" >&2
    echo "       $0 --still-current REPORT PACKAGE.deb" >&2
    exit 2
}

mode=release

case "${1:-}" in
    --ci) mode=ci; shift ;;
    --still-current) mode=check; shift ;;
esac

if [[ "$mode" == check ]]; then
    [[ $# -eq 2 ]] || usage
    gate_report="$1"
    shift
fi

[[ $# -ge 1 ]] || usage

candidate="$(realpath "$1")"
shift
extra_from=("$@")

[[ -f "$candidate" ]] || { echo "Package not found: $candidate" >&2; exit 1; }

version="$(release_package_version "$candidate")"
release_require_version "$version"

# The name a release is published under is the version dpkg reads out of
# it. A file called 0.2.6.6 that says it is 0.2.6.5 is the wrong file.
if [[ "$(basename "$candidate")" != "$(release_package_name "$version")" ]]; then
    echo "$(basename "$candidate") says it is $version." >&2
    exit 1
fi

hash="$(sha256sum "$candidate" | awk '{print $1}')"

# The version a channel serves, read the way a classroom reads it.
served() {
    curl -fsS -H 'Cache-Control: no-cache' "$RELEASE_URL/$1/manifest.json" \
        | python3 -c 'import json, sys; print(json.load(sys.stdin)["version"])'
}

if [[ "$mode" == check ]]; then
    stale() { echo "The gate report $gate_report cannot be relied on: $1" >&2; exit 1; }
    name="$(basename "$candidate")"

    [[ -f "$gate_report" ]] || stale "there is no such file"
    grep -qx "release gate for $name" "$gate_report" || stale "it is not about $name"
    grep -qx "mode release" "$gate_report" || stale "it is not a release gate's report"
    grep -qx "sha256 $hash" "$gate_report" || stale "it is about other bytes than $hash"
    [[ "$(tail -n 1 "$gate_report")" == *": $name passed the release gate" ]] \
        || stale "it does not end in a pass"
    ! grep -q '^SKIP' "$gate_report" || stale "it skipped something"
    grep -q "^PASS  fresh install of $version " "$gate_report" || stale "it has no fresh install"

    for channel in canary stable; do
        now="$(served "$channel")"
        grep -qF "PASS  upgrade $now -> $version on a $channel room ($channel serves $now)" "$gate_report" \
            || stale "$channel serves $now now, and the report did not upgrade from that"
    done

    echo "The gate report for $name, sha256 $hash, is current: canary and stable are where it left them."
    exit 0
fi

report="${RELEASE_GATE_REPORT:-}"
work="$(mktemp -d)"
trap 'rm -rf "$work"' EXIT

record() {
    printf '%s\n' "$1"
    [[ -z "$report" ]] || printf '%s\n' "$1" >> "$report"
}

[[ -z "$report" ]] || : > "$report"
record "release gate for $(basename "$candidate")"
record "sha256 $hash"
record "mode $mode"
record "started $(date -u +%Y-%m-%dT%H:%M:%SZ)"

# A channel's current package, fetched as a classroom fetches it and
# proven to be what the manifest promises.
fetch_channel() {
    local channel="$1" manifest from from_hash name got

    manifest="$(curl -fsS -H 'Cache-Control: no-cache' "$RELEASE_URL/$channel/manifest.json")"
    read -r from from_hash < <(python3 -c 'import json, sys
m = json.loads(sys.argv[1])
print(m["version"], m["sha256"])' "$manifest")

    release_require_version "$from"
    [[ "$from_hash" =~ ^[0-9a-f]{64}$ ]]
    name="$(release_package_name "$from")"
    curl -fsS -o "$work/$name" "$RELEASE_URL/packages/$name"
    got="$(sha256sum "$work/$name" | awk '{print $1}')"

    if [[ "$got" != "$from_hash" ]]; then
        echo "$channel serves $name with sha256 $got; its manifest says $from_hash" >&2
        return 1
    fi

    printf '%s\n' "$work/$name"
}

# A published release by version, for the rooms still on an older one.
fetch_version() {
    local from="$1" name

    release_require_version "$from"
    name="$(release_package_name "$from")"
    curl -fsS -o "$work/$name" "$RELEASE_URL/packages/$name"

    if [[ "$(release_package_version "$work/$name")" != "$from" ]]; then
        echo "$name does not say it is $from" >&2
        return 1
    fi

    printf '%s\n' "$work/$name"
}

run() {
    local label="$1" started
    shift
    started=$SECONDS

    echo
    echo "== $label"
    "$@"
    record "PASS  $label  ($(( (SECONDS - started) / 60 )) min)"
}

# A new machine is a stable room: that is what a fresh device.conf says,
# so that is the manifest its updater is asked about.
run "fresh install of $version (a new machine, on stable)" \
    env VALIDATION_CHANNEL=stable \
    "$ROOT/tools/validate-trixie-release.sh" "$candidate"

for channel in canary stable; do
    previous="$(fetch_channel "$channel")"
    from="$(release_package_version "$previous")"

    if ! release_version_gt "$version" "$from"; then
        if [[ "$mode" == ci ]]; then
            record "SKIP  upgrade $from -> $version on a $channel room: $channel serves $from, not older than this commit's VERSION (a CI build, not a release)"
            continue
        fi

        echo "$channel is on $from; $version is not newer, so no room could take it." >&2
        exit 1
    fi

    run "upgrade $from -> $version on a $channel room ($channel serves $from)" \
        env VALIDATION_CHANNEL="$channel" \
        "$ROOT/tools/validate-trixie-release.sh" "$candidate" "$previous"
done

for from in "${extra_from[@]}"; do
    previous="$(fetch_version "$from")"

    run "upgrade $from -> $version on a stable room" \
        env VALIDATION_CHANNEL=stable \
        "$ROOT/tools/validate-trixie-release.sh" "$candidate" "$previous"
done

if [[ "$mode" == ci ]]; then
    record "finished $(date -u +%Y-%m-%dT%H:%M:%SZ): $(basename "$candidate") passed the CI gate, which is not a release gate"
else
    record "finished $(date -u +%Y-%m-%dT%H:%M:%SZ): $(basename "$candidate") passed the release gate"
fi