#!/bin/bash
# Run the release workflow for a channel when work is queued.
# Usage: auto-release <edge|rc|stable> [<arch>|all]
#
# With no architecture (what the timers pass), every published architecture
# is processed in turn, each against its own queue and its own backoff, so a
# failing aarch64 build never holds up x86_64 or the other way round.
#
# Safe to run on a tight schedule. Three guards make that true:
#
#   1. Nothing queued -> exit immediately (the common case).
#   2. A release already running -> skip this tick. The lock is taken
#      non-blocking on purpose: waiting would pile up one stalled process per
#      tick behind a long build, and they would all stampede when it finished.
#   3. The last attempt failed -> back off exponentially rather than rebuild
#      the same broken tree every few minutes. A change to the repository
#      (new commit) clears the backoff immediately, because that is the thing
#      most likely to have fixed it.

set -e

BUILD_ROOT=$(realpath "${BASH_SOURCE[0]%/*}/..")
source "$BUILD_ROOT/helpers/message-helpers.sh"
source "$BUILD_ROOT/helpers/paths.sh"
source "$BUILD_ROOT/helpers/lock-helpers.sh"

MIRROR="${1:-}"
ARCH_ARG="${2:-all}"

# Backoff schedule: 10m, 20m, 40m, 80m, 160m, 320m, then hourly-ish forever
# (capped at 6h, the cadence this system ran at before frequent timers).
BACKOFF_BASE_SECONDS="${OMARCHY_BACKOFF_BASE:-600}"
BACKOFF_MAX_SECONDS="${OMARCHY_BACKOFF_MAX:-21600}"

if [[ -z "$MIRROR" ]]; then
  print_error "Usage: $0 <mirror> [<arch>|all]"
  echo "  mirror: edge, rc, or stable"
  echo "  arch:   one of $VALID_ARCHES, or all (default) for every published architecture"
  exit 1
fi

if [[ "$MIRROR" != "edge" && "$MIRROR" != "rc" && "$MIRROR" != "stable" ]]; then
  print_error "Invalid mirror: $MIRROR (must be 'edge', 'rc', or 'stable')"
  exit 1
fi

if [[ "$ARCH_ARG" == "all" ]]; then
  ARCHES=$(published_arches)
else
  require_valid_arch "$ARCH_ARG"
  ARCHES="$ARCH_ARG"
fi

# The build inputs are this checkout's contents; its HEAD identifies them.
current_fingerprint() {
  git -C "$BUILD_ROOT" rev-parse HEAD 2>/dev/null || echo "unknown"
}

backoff_seconds() {
  local count="$1" delay="$BACKOFF_BASE_SECONDS"
  while ((count > 1)); do
    delay=$((delay * 2))
    ((delay >= BACKOFF_MAX_SECONDS)) && { delay=$BACKOFF_MAX_SECONDS; break; }
    count=$((count - 1))
  done
  echo "$delay"
}

# Returns 0 when this architecture's queue was processed (or was empty), 1 when
# the release failed. Backoff and "someone else holds the lock" are not
# failures: they are this tick deciding to do nothing.
release_arch() {
  local arch="$1"
  local state_file fail_file
  state_file=$(sync_queue_file "$MIRROR" "$arch")
  fail_file=$(sync_fail_file "$MIRROR" "$arch")

  # A queue written under the pre-architecture name belongs to x86_64.
  if [[ "$arch" == "x86_64" && ! -f "$state_file" && -f "$(legacy_sync_queue_file "$MIRROR")" ]]; then
    state_file=$(legacy_sync_queue_file "$MIRROR")
  fi
  if [[ "$arch" == "x86_64" && ! -f "$fail_file" && -f "$(legacy_sync_fail_file "$MIRROR")" ]]; then
    fail_file=$(legacy_sync_fail_file "$MIRROR")
  fi

  # Nothing queued: stay quiet. At a 5-minute cadence this is most
  # invocations, and a header for each would bury the runs that matter in
  # the journal.
  [[ -f "$state_file" ]] || return 0

  print_header "Processing Sync for $MIRROR ($arch)"

  local fail_count=0 failed_at failed_fingerprint delay now retry_at
  if [[ -f "$fail_file" ]]; then
    FAILURE_COUNT=0 FAILURE_AT=0 FAILURE_FINGERPRINT=""
    # shellcheck disable=SC1090
    source "$fail_file" 2>/dev/null || true
    fail_count="${FAILURE_COUNT:-0}"
    failed_at="${FAILURE_AT:-0}"
    failed_fingerprint="${FAILURE_FINGERPRINT:-}"

    if [[ "$failed_fingerprint" != "$(current_fingerprint)" ]]; then
      print_info "Repository changed since the last failure — clearing backoff and retrying"
      rm -f "$fail_file"
      fail_count=0
    else
      delay=$(backoff_seconds "$fail_count")
      now=$(date +%s)
      retry_at=$((failed_at + delay))
      if ((now < retry_at)); then
        print_warning "$MIRROR ($arch) has failed $fail_count time(s) on this tree — not retrying until $(date -d "@$retry_at" '+%H:%M:%S' 2>/dev/null || echo "+$((retry_at - now))s")"
        echo "  Push a fix (any new commit clears this), or: rm $fail_file"
        return 0
      fi
      print_info "Backoff elapsed — retrying $MIRROR ($arch) (failure #$((fail_count + 1)) if this fails)"
    fi
  fi

  # Non-blocking: a build in progress means this tick has nothing to do. The
  # lock is reentrant, so once this run holds it the remaining architectures
  # run under the same acquisition.
  if ! try_release_lock; then
    local holder
    holder=$(release_lock_holder)
    print_info "A release is already running (${holder:-holder unknown}) — skipping this tick"
    return 0
  fi

  print_info "State file found: $state_file"
  print_info "Starting release workflow for $MIRROR ($arch)..."

  if "$BUILD_ROOT/bin/repo" release --mirror "$MIRROR" --arch "$arch" --skip-prod-check; then
    print_success "Release completed successfully for $MIRROR ($arch)"
    local completed_state=("$state_file" "$fail_file")
    if [[ "$arch" == "x86_64" ]]; then
      completed_state+=("$(legacy_sync_queue_file "$MIRROR")" "$(legacy_sync_fail_file "$MIRROR")")
    fi
    if ! rm -f "${completed_state[@]}"; then
      print_error "Release succeeded, but its queue state could not be cleared"
      return 1
    fi
    print_success "State file removed: $state_file"
    return 0
  fi

  fail_count=$((fail_count + 1))
  if ! cat >"$fail_file" <<EOF
FAILURE_COUNT=$fail_count
FAILURE_AT=$(date +%s)
FAILURE_FINGERPRINT=$(current_fingerprint)
EOF
  then
    print_error "Could not record failure state: $fail_file"
    return 1
  fi
  local next
  next=$(backoff_seconds "$fail_count")
  print_error "Release failed for $MIRROR ($arch) (attempt $fail_count)"
  print_warning "State file retained for retry: $state_file"
  print_warning "Backing off $((next / 60))m before the next attempt; a new commit retries sooner"
  return 1
}

status=0
for arch in $ARCHES; do
  release_arch "$arch" || status=1
done
exit "$status"