#!/usr/bin/env bash
set -euo pipefail
umask 077

ROOT=$(CDPATH='' cd -- "$(dirname -- "$0")/.." && pwd)
action=${1:-plan}
config=${2:-"$ROOT/tmp/production-operations/backup.env"}
restic="$ROOT/.tools/restic/restic"
restore_image='postgis/postgis:18-3.6-alpine@sha256:05d68c7f0f19b9aa0bf7c4a2049b2e8b38b44a63116392b95726a4c913766cf6'

case "$action" in
  plan | init | run | check | restore-drill) ;;
  *)
    echo "Usage: $0 [plan|init|run|check|restore-drill] [CONFIG]" >&2
    exit 2
    ;;
esac

if [[ "$config" != /* ]]; then
  config="$ROOT/$config"
fi

if [[ ! -f "$config" ]]; then
  echo "Operations configuration does not exist: $config" >&2
  exit 2
fi

if [[ "$(stat -c '%a' "$config")" != 600 ]]; then
  echo "Operations configuration must have mode 0600: $config" >&2
  exit 2
fi

# shellcheck source=/dev/null
source "$config"

: "${PRODUCTION_SSH_TARGET:?Set PRODUCTION_SSH_TARGET}"
: "${PRODUCTION_REMOTE_ROOT:?Set PRODUCTION_REMOTE_ROOT}"
: "${PRODUCTION_EXPECTED_ENVIRONMENT:?Set PRODUCTION_EXPECTED_ENVIRONMENT}"
: "${OFFSITE_RESTIC_REPOSITORY:?Set OFFSITE_RESTIC_REPOSITORY}"
: "${OFFSITE_RESTIC_PASSWORD_FILE:?Set OFFSITE_RESTIC_PASSWORD_FILE}"
: "${OFFSITE_RESTIC_HOST:?Set OFFSITE_RESTIC_HOST}"
: "${OFFSITE_RESTIC_TAG:?Set OFFSITE_RESTIC_TAG}"
OFFSITE_BACKUP_HEARTBEAT_PATH=${OFFSITE_BACKUP_HEARTBEAT_PATH:-/home/simple/.local/state/who-need-help/production-backup.json}

if [[ "$PRODUCTION_EXPECTED_ENVIRONMENT" != production ]]; then
  echo "The source environment must be exactly production." >&2
  exit 2
fi

case "$PRODUCTION_REMOTE_ROOT" in
  /srv/who_need_help-production) ;;
  *)
    echo "The production root is outside the reviewed deployment path." >&2
    exit 2
    ;;
esac

case "$OFFSITE_RESTIC_REPOSITORY" in
  sftp:*) ;;
  *)
    echo "This workflow currently accepts only an encrypted Restic SFTP repository." >&2
    exit 2
    ;;
esac

if [[ "$OFFSITE_BACKUP_HEARTBEAT_PATH" != /home/simple/.local/state/who-need-help/production-backup.json ]]; then
  echo "The backup heartbeat path is outside the reviewed independent-monitor state path." >&2
  exit 2
fi

if [[ ! -f "$OFFSITE_RESTIC_PASSWORD_FILE" ]] ||
  [[ "$(stat -c '%a' "$OFFSITE_RESTIC_PASSWORD_FILE")" != 600 ]]; then
  echo "The Restic password file must exist with mode 0600." >&2
  exit 2
fi

if [[ ! -x "$restic" ]]; then
  echo "Pinned Restic is unavailable. Run ./scripts/bootstrap-restic.sh first." >&2
  exit 2
fi

for command in docker flock grep jq openssl pg_restore scp sha256sum ssh; do
  command -v "$command" >/dev/null 2>&1 || {
    echo "Required command is unavailable: $command" >&2
    exit 2
  }
done

export RESTIC_REPOSITORY="$OFFSITE_RESTIC_REPOSITORY"
export RESTIC_PASSWORD_FILE="$OFFSITE_RESTIC_PASSWORD_FILE"
export RESTIC_CACHE_DIR="$ROOT/tmp/production-operations/restic-cache"

mkdir -p "$RESTIC_CACHE_DIR"
chmod 700 "$ROOT/tmp" "$ROOT/tmp/production-operations" "$RESTIC_CACHE_DIR"

source_host=$(ssh -G "$PRODUCTION_SSH_TARGET" | awk '$1 == "hostname" {print $2; exit}')
repository_alias=${OFFSITE_RESTIC_REPOSITORY#sftp:}
repository_alias=${repository_alias%%:*}
repository_host=$(ssh -G "$repository_alias" | awk '$1 == "hostname" {print $2; exit}')

if [[ -z "$source_host" || -z "$repository_host" ]] ||
  [[ "$source_host" == "$repository_host" ]]; then
  echo "The repository host must resolve and differ from production." >&2
  exit 2
fi

check_source() {
  ssh -o BatchMode=yes "$PRODUCTION_SSH_TARGET" \
    "bash -s -- '$PRODUCTION_REMOTE_ROOT/.env' --check-only '$PRODUCTION_EXPECTED_ENVIRONMENT'" \
    <"$ROOT/scripts/backup-external-postgres.sh"
}

repo_initialized() {
  "$restic" snapshots --json >/dev/null 2>&1
}

printf 'Production SSH target: %s (%s)\n' "$PRODUCTION_SSH_TARGET" "$source_host"
printf 'Production root: %s\n' "$PRODUCTION_REMOTE_ROOT"
printf 'Encrypted repository: %s (%s)\n' "$OFFSITE_RESTIC_REPOSITORY" "$repository_host"
printf 'Restic: %s\n' "$($restic version)"

if [[ "$action" == plan ]]; then
  check_source
  if repo_initialized; then
    echo "Encrypted repository opened successfully."
  else
    echo "Encrypted repository is not initialized or cannot be opened."
  fi
  echo "Plan completed without changing production or the repository."
  exit 0
fi

if [[ "$action" == init ]]; then
  confirmation="$OFFSITE_RESTIC_REPOSITORY"
  if [[ "${WNH_OFFSITE_BACKUP_INIT_CONFIRM:-}" != "$confirmation" ]]; then
    echo "Repository initialization requires exact confirmation:" >&2
    echo "WNH_OFFSITE_BACKUP_INIT_CONFIRM=$confirmation $0 init '$config'" >&2
    exit 2
  fi

  check_source
  if repo_initialized; then
    echo "Encrypted repository is already initialized; no change was made."
    exit 0
  fi

  "$restic" init
  "$restic" check
  echo "Encrypted off-server Restic repository initialized and opened successfully."
  exit 0
fi

repo_initialized || {
  echo "Encrypted repository cannot be opened. Initialize it first." >&2
  exit 2
}

if [[ "$action" == check ]]; then
  "$restic" check --read-data
  echo "Encrypted repository full-data check passed."
  exit 0
fi

if [[ "$action" == restore-drill ]]; then
  snapshot_id=$($restic snapshots --json --host "$OFFSITE_RESTIC_HOST" \
    --tag "$OFFSITE_RESTIC_TAG" --latest 1 | jq -r '.[0].short_id // empty')
  if [[ -z "$snapshot_id" ]]; then
    echo "No production backup snapshot is available for a restore drill." >&2
    exit 1
  fi
else
  snapshot_id=
fi

lock_file="$ROOT/tmp/production-operations/backup.lock"
exec 9>"$lock_file"
flock --nonblock 9 || {
  echo "Another production backup or restore drill is already running." >&2
  exit 1
}

run_id=$(date -u +%Y%m%dT%H%M%SZ)-$$
work_dir=$(mktemp -d "$ROOT/tmp/production-operations/run-$run_id.XXXXXX")
evidence_dir="$ROOT/output/production-operations/$run_id"
remote_dump="$PRODUCTION_REMOTE_ROOT/output/backups/production/scheduled-$run_id.dump"
remote_created=false
restore_container="wnh-production-restore-$run_id"
restore_volume="wnh_production_restore_${run_id//[^a-zA-Z0-9]/_}"
restore_started=false
restore_volume_created=false
heartbeat_staged=false
heartbeat_remote_tmp="$OFFSITE_BACKUP_HEARTBEAT_PATH.tmp-$run_id"

mkdir -p "$evidence_dir"
chmod 700 "$ROOT/output" "$ROOT/output/production-operations" "$evidence_dir" "$work_dir"

cleanup() {
  trap - EXIT HUP INT TERM
  if [[ "$restore_started" == true ]]; then
    docker rm --force "$restore_container" >/dev/null 2>&1 || true
  fi
  if [[ "$restore_volume_created" == true ]]; then
    docker volume rm "$restore_volume" >/dev/null 2>&1 || true
  fi
  if [[ "$remote_created" == true ]]; then
    ssh -o BatchMode=yes "$PRODUCTION_SSH_TARGET" \
      "rm -f -- '$remote_dump' '$remote_dump.sha256' '$remote_dump.metadata'" \
      >/dev/null 2>&1 || true
  fi
  if [[ "$heartbeat_staged" == true ]]; then
    ssh -o BatchMode=yes "$repository_alias" \
      "rm -f -- '$heartbeat_remote_tmp'" >/dev/null 2>&1 || true
  fi
  rm -rf "$work_dir"
}
trap cleanup EXIT HUP INT TERM

restore_snapshot() {
  local selected_snapshot=$1
  local dump="$work_dir/production.dump"
  local password
  local health
  local tables
  local migrations
  local postgis

  "$restic" dump "$selected_snapshot" /production.dump >"$dump"
  [[ -s "$dump" ]] || {
    echo "Restic restored an empty database dump." >&2
    return 1
  }
  pg_restore --list "$dump" >"$evidence_dir/pg-restore-catalog.txt"

  if ! docker image inspect "$restore_image" >/dev/null 2>&1; then
    docker pull "$restore_image" >"$evidence_dir/postgis-pull.txt"
  fi

  password=$(openssl rand -base64 36 | tr -d '\n')
  docker volume create "$restore_volume" >/dev/null
  restore_volume_created=true
  docker run --detach \
    --name "$restore_container" \
    --env POSTGRES_PASSWORD="$password" \
    --env POSTGRES_DB=postgres \
    --volume "$restore_volume:/var/lib/postgresql" \
    --health-cmd='pg_isready --username postgres --dbname postgres' \
    --health-interval=1s \
    --health-timeout=2s \
    --health-retries=120 \
    "$restore_image" >/dev/null
  restore_started=true

  # A freshly initialized postgres/postgis container briefly accepts
  # connections through its temporary bootstrap server. Wait until the image
  # has completed that bootstrap and started the final server before restoring.
  while ! docker logs "$restore_container" 2>&1 |
    grep -Fq 'PostgreSQL init process complete; ready for start up.'; do
    if [[ "$(docker inspect --format '{{.State.Running}}' "$restore_container")" != true ]]; then
      docker logs "$restore_container" >"$evidence_dir/restore-postgres.log" 2>&1 || true
      echo "Isolated restore PostgreSQL exited during initialization." >&2
      return 1
    fi
    sleep 1
  done

  while true; do
    health=$(docker inspect --format '{{if .State.Health}}{{.State.Health.Status}}{{else}}missing{{end}}' "$restore_container")
    case "$health" in
      healthy) break ;;
      unhealthy)
        docker logs "$restore_container" >"$evidence_dir/restore-postgres.log" 2>&1 || true
        echo "Isolated restore PostgreSQL became unhealthy." >&2
        return 1
        ;;
    esac
    sleep 1
  done

  # The PostGIS image initializes its requested database with PostGIS already
  # installed. Restore into a database created from template0 instead, so the
  # archive remains responsible for recreating its own extensions and schema.
  docker exec "$restore_container" createdb \
    --username postgres \
    --template template0 \
    restore_check

  if ! docker exec --interactive "$restore_container" pg_restore \
    --username postgres \
    --dbname restore_check \
    --exit-on-error \
    --no-owner \
    --no-privileges <"$dump"; then
    docker logs "$restore_container" >"$evidence_dir/restore-postgres.log" 2>&1 || true
    docker inspect "$restore_container" >"$evidence_dir/restore-container.json" 2>&1 || true
    echo "Isolated restore failed; container evidence was retained." >&2
    return 1
  fi

  tables=$(docker exec "$restore_container" psql \
    --username postgres --dbname restore_check --tuples-only --no-align \
    --command="select count(*) from pg_tables where schemaname='public' and tablename <> 'spatial_ref_sys';")
  migrations=$(docker exec "$restore_container" psql \
    --username postgres --dbname restore_check --tuples-only --no-align \
    --command='select count(*) from schema_migrations;')
  postgis=$(docker exec "$restore_container" psql \
    --username postgres --dbname restore_check --tuples-only --no-align \
    --command='select PostGIS_Lib_Version();')

  if [[ ! "$tables" =~ ^[1-9][0-9]*$ ]] || [[ ! "$migrations" =~ ^[1-9][0-9]*$ ]]; then
    echo "The isolated restore does not contain the expected application schema." >&2
    return 1
  fi

  {
    printf 'snapshot_id=%s\n' "$selected_snapshot"
    printf 'application_tables=%s\n' "$tables"
    printf 'schema_migrations=%s\n' "$migrations"
    printf 'postgis_version=%s\n' "$postgis"
    printf 'verified_at=%s\n' "$(date -u +%Y-%m-%dT%H:%M:%SZ)"
  } >"$evidence_dir/restore-drill.txt"
  chmod 600 "$evidence_dir/restore-drill.txt" "$evidence_dir/pg-restore-catalog.txt"

  docker rm --force "$restore_container" >/dev/null
  restore_started=false
  docker volume rm "$restore_volume" >/dev/null
  restore_volume_created=false
  rm -f "$dump"
}

if [[ "$action" == restore-drill ]]; then
  restore_snapshot "$snapshot_id"
  echo "Isolated restore drill passed for snapshot: $snapshot_id"
  printf 'Non-secret evidence: %s\n' "$evidence_dir"
  exit 0
fi

check_source

ssh -o BatchMode=yes "$PRODUCTION_SSH_TARGET" \
  "bash -s -- '$PRODUCTION_REMOTE_ROOT/.env' '$remote_dump' '$PRODUCTION_EXPECTED_ENVIRONMENT'" \
  <"$ROOT/scripts/backup-external-postgres.sh"
remote_created=true

scp -p \
  "$PRODUCTION_SSH_TARGET:$remote_dump" \
  "$PRODUCTION_SSH_TARGET:$remote_dump.sha256" \
  "$PRODUCTION_SSH_TARGET:$remote_dump.metadata" \
  "$work_dir/"

dump="$work_dir/$(basename -- "$remote_dump")"
checksum="$dump.sha256"
metadata="$dump.metadata"

(
  cd "$work_dir"
  sha256sum --check "$(basename -- "$checksum")"
) >"$evidence_dir/source-checksum.txt"
pg_restore --list "$dump" >"$evidence_dir/source-catalog.txt"
cp "$checksum" "$metadata" "$evidence_dir/"
chmod 600 "$evidence_dir"/*

run_tag="$OFFSITE_RESTIC_TAG-$run_id"
backup_json="$evidence_dir/restic-backup.jsonl"
"$restic" backup \
  --json \
  --host "$OFFSITE_RESTIC_HOST" \
  --tag "$OFFSITE_RESTIC_TAG" \
  --tag "$run_tag" \
  --stdin-filename production.dump \
  --stdin-from-command -- cat "$dump" >"$backup_json"

snapshot_id=$(jq -r 'select(.message_type == "summary") | .snapshot_id // empty' "$backup_json" | tail -n 1)
if [[ -z "$snapshot_id" ]]; then
  echo "Restic did not report a completed snapshot." >&2
  exit 1
fi

snapshot_matches=$($restic snapshots --json --tag "$run_tag" | jq 'length')
if [[ "$snapshot_matches" != 1 ]]; then
  echo "The run tag did not resolve to exactly one snapshot." >&2
  exit 1
fi

"$restic" check --read-data >"$evidence_dir/restic-check.txt"
restore_snapshot "$snapshot_id"

printf '%s\n' "$snapshot_id" >"$evidence_dir/snapshot-id.txt"
chmod 600 "$evidence_dir"/*

ssh -o BatchMode=yes "$PRODUCTION_SSH_TARGET" \
  "rm -f -- '$remote_dump' '$remote_dump.sha256' '$remote_dump.metadata'"
remote_created=false

heartbeat="$work_dir/production-backup-heartbeat.json"
jq -n \
  --arg snapshot_id "$snapshot_id" \
  --arg verified_at "$(date -u +%Y-%m-%dT%H:%M:%SZ)" \
  '{snapshot_id: $snapshot_id, verified_at: $verified_at, restore_verified: true}' \
  >"$heartbeat"
chmod 600 "$heartbeat"
ssh -o BatchMode=yes "$repository_alias" \
  "install -d -m 700 '$(dirname -- "$OFFSITE_BACKUP_HEARTBEAT_PATH")'"
heartbeat_staged=true
scp -q "$heartbeat" "$repository_alias:$heartbeat_remote_tmp"
ssh -o BatchMode=yes "$repository_alias" \
  "chmod 600 '$heartbeat_remote_tmp' && mv -f -- '$heartbeat_remote_tmp' '$OFFSITE_BACKUP_HEARTBEAT_PATH'"
heartbeat_staged=false

echo "Encrypted off-server backup and isolated restore drill passed."
printf 'Snapshot: %s\n' "$snapshot_id"
printf 'Non-secret evidence: %s\n' "$evidence_dir"