#!/usr/bin/env bash
# OpenBao source backend for render-secrets.sh. Sourced, never run directly.
#
# Two functions:
#   thermograph_openbao_source <env>        -> merged dotenv on STDOUT
#   thermograph_render_openbao  <env> <out> -> source, then write <out>
#
# render_thermograph_secrets in render-secrets.sh dispatches to the second when
# TG_SECRETS_BACKEND=openbao, and is otherwise completely untouched — so the SOPS path
# keeps byte-identical behaviour and all new risk is confined to this file. See the
# note above thermograph_render_openbao on why the write path is duplicated here
# rather than shared, and when to consolidate.
#
# WHY OUTPUT SHAPE IS FROZEN: /etc/thermograph.env must stay raw, UNQUOTED KEY=value.
# Centralis' secrets_inventory / secrets_render compare that file textually
# (deploy/secrets/README.md:206-210), compose reads it via `env_file:`, and the Swarm
# stack's env-entrypoint.sh parses it line by line. Quoting it "properly" would be an
# improvement in isolation and a silent break in context.

# thermograph_openbao_source <env_name>
#
# Reads the common set then the per-environment set and merges them with the
# environment winning — the same last-wins semantic as the SOPS concatenation, except
# performed explicitly here because OpenBao returns a map per path rather than a
# stream that can simply be appended.
thermograph_openbao_source() {
  local env_name="${1:?env name required}"
  local addr="${THERMOGRAPH_BAO_ADDR:-https://10.10.0.1:8200}"
  local mount="${THERMOGRAPH_BAO_MOUNT:-thermograph}"
  # Explicit override first, then the per-environment value env-topology.sh derives,
  # then the conventional path. Same precedence shape as render-secrets.sh:44's
  # THERMOGRAPH_SECRETS_BACKEND / TG_SECRETS_BACKEND pair, for the same reason: the
  # THERMOGRAPH_-prefixed name is the by-hand escape hatch, the TG_ one is what the
  # deploy path sets. Falling straight through to the bare default is what made beta
  # authenticate as tg-prod and get denied its own path.
  local approle="${THERMOGRAPH_BAO_APPROLE:-${TG_BAO_APPROLE:-/etc/thermograph/openbao-approle}}"
  local ca="${THERMOGRAPH_BAO_CACERT:-/etc/thermograph/openbao-ca.crt}"

  command -v bao >/dev/null 2>&1 || {
    echo "!! bao CLI not installed but this host is configured for the openbao backend" >&2
    return 1
  }
  command -v python3 >/dev/null 2>&1 || {
    echo "!! python3 required to render dotenv from OpenBao JSON" >&2
    return 1
  }

  # AppRole credentials: role_id and secret_id, one per line, 0400 root — the same
  # protection level as /etc/thermograph/age.key today. Read directly if we can, else
  # via sudo, mirroring how render-secrets.sh lifts the age key.
  local creds
  if [ -r "$approle" ]; then
    creds=$(cat "$approle")
  else
    creds=$(sudo cat "$approle" 2>/dev/null || true)
  fi
  [ -n "$creds" ] || {
    echo "!! cannot read OpenBao AppRole credentials at $approle (need sudo)" >&2
    return 1
  }

  local role_id secret_id
  role_id=$(printf '%s\n' "$creds" | sed -n '1p')
  secret_id=$(printf '%s\n' "$creds" | sed -n '2p')
  [ -n "$role_id" ] && [ -n "$secret_id" ] || {
    echo "!! $approle malformed: expected role_id on line 1, secret_id on line 2" >&2
    return 1
  }

  export BAO_ADDR="$addr"
  [ -f "$ca" ] && export BAO_CACERT="$ca"

  # Exchange the AppRole for a short-lived token. The token TTL is set on the role
  # (see bootstrap.sh) and is deliberately measured in minutes: it only has to
  # outlive one render.
  local token
  token=$(bao write -field=token auth/approle/login \
            role_id="$role_id" secret_id="$secret_id" 2>/dev/null) || {
    echo "!! OpenBao AppRole login failed for env='${env_name}'" >&2
    echo "!! check that OpenBao at $addr is reachable and UNSEALED" >&2
    return 1
  }
  export BAO_TOKEN="$token"

  # Fetch. `common` is skipped for dev by the same flag the SOPS path uses — but note
  # that on the OpenBao path the flag is belt, not braces: dev's AppRole is bound to
  # the tg-host-dev policy, which DENIES thermograph/data/common outright. If this
  # flag is ever forgotten at a call site, dev gets a 403 rather than a file full of
  # production credentials. That inversion — from "the caller must remember" to "the
  # store refuses" — is the main reason for this migration.
  local common_json="" env_json
  if [ "${THERMOGRAPH_SECRETS_SKIP_COMMON:-0}" != 1 ]; then
    common_json=$(bao kv get -format=json -mount="$mount" common 2>/dev/null) || {
      echo "!! cannot read ${mount}/common for env='${env_name}'" >&2
      echo "!! if this is dev, THERMOGRAPH_SECRETS_SKIP_COMMON=1 was not set and the" >&2
      echo "!! tg-host-dev policy correctly refused — that is the guard working." >&2
      return 1
    }
  fi

  env_json=$(bao kv get -format=json -mount="$mount" "env/${env_name}" 2>/dev/null) || {
    echo "!! cannot read ${mount}/env/${env_name}" >&2
    return 1
  }

  # Merge and emit. Python rather than jq because jq is not installed on these hosts
  # and python3 is (the Centralis renderer already relies on it).
  #
  # This step also enforces the two invariants the dotenv format cannot express:
  #   * a value containing a newline is REJECTED, because it would silently become
  #     two lines and the second would parse as a bogus KEY=value or be dropped;
  #   * a value containing a shell metacharacter is REJECTED, because
  #     /etc/thermograph.env is sourced by bash in six places (deploy.sh:133,
  #     deploy-stack.sh:98, both daemon entrypoints, ops-cron.yml:85, terraform), so
  #     `$(...)` or a backtick in a secret is a live command-execution path on the
  #     deploy host. The SOPS path has always had this hazard and has never tripped it
  #     only because every current value happens to be alphanumeric. Refusing here
  #     turns a latent code-execution bug into a loud render failure.
  THERMOGRAPH_BAO_COMMON="$common_json" \
  THERMOGRAPH_BAO_ENV="$env_json" \
  python3 - <<'PY'
import json, os, re, sys

def load(raw):
    if not raw:
        return {}
    doc = json.loads(raw)
    return doc.get("data", {}).get("data", {}) or {}

merged = {}
# common first, environment second: last-wins, matching the SOPS concatenation order.
for src in ("THERMOGRAPH_BAO_COMMON", "THERMOGRAPH_BAO_ENV"):
    merged.update(load(os.environ.get(src, "")))

KEY_RE = re.compile(r"^[A-Za-z_][A-Za-z0-9_]*$")
# Characters that change meaning when the file is sourced by bash.
UNSAFE = set("`$\\\"'")

bad = []
lines = []
# Validate EVERYTHING before emitting a single byte. Printing as we go would leave
# partial output on stdout when a later key fails, and render-secrets.sh's whole
# discipline is that a failed source never produces a partial env file.
for key in sorted(merged):
    if not KEY_RE.match(key):
        bad.append(f"{key}: not a valid env var name")
        continue
    val = merged[key]
    if val is None:
        val = ""
    if not isinstance(val, str):
        val = json.dumps(val, separators=(",", ":"))
    if "\n" in val or "\r" in val:
        bad.append(f"{key}: value contains a newline (would corrupt the dotenv)")
        continue
    if UNSAFE & set(val):
        bad.append(
            f"{key}: value contains a shell metacharacter (one of ` $ \\ \" ') and "
            f"/etc/thermograph.env is sourced by bash — refusing"
        )
        continue
    lines.append(f"{key}={val}")

if bad:
    sys.stderr.write("!! refusing to render; unsafe values:\n")
    for line in bad:
        sys.stderr.write(f"!!   {line}\n")
    sys.exit(1)

if not lines:
    sys.stderr.write("!! refusing to render: OpenBao returned zero keys\n")
    sys.exit(1)

sys.stdout.write("\n".join(lines) + "\n")
PY
}

# thermograph_render_openbao <env_name> <out_file>
#
# The OpenBao equivalent of render_thermograph_secrets: source, then write.
#
# ON THE DUPLICATED WRITE PATH. The write logic below mirrors
# render-secrets.sh:130-154 rather than being factored out and shared. That is a
# deliberate, temporary choice, not an oversight:
#
#   render-secrets.sh is on the deploy path for all three environments and there is no
#   test suite in front of it (infra/CLAUDE.md: "Shell here runs as root over SSH
#   against live hosts with no test suite in front of it"). Extracting the write path
#   would mean the SOPS render — which currently works — starts flowing through newly
#   moved code that cannot be tested end-to-end from here. An early-return branch keeps
#   the SOPS path byte-identical and confines all new risk to the new backend.
#
#   CONSOLIDATE THESE after prod has been on the OpenBao backend for a full release
#   cycle and the SOPS path is being deleted anyway. Until then, a change to one write
#   path must be made in both — which is exactly the cost being accepted here.
thermograph_render_openbao() {
  local env_name="${1:?env name required}"
  local out="${2:?output path required}"

  echo "==> Rendering $out from OpenBao (env=${env_name})"

  local tmp; tmp=$(mktemp)
  # Holds DECRYPTED secrets. Removed on every exit path. Deliberately not a
  # `trap ... RETURN` — see render-secrets.sh:82-91 for why that is actively wrong in
  # a sourced function (the trap persists into the caller and re-fires on its next
  # `source`, where the local is unset and `set -u` makes it fatal and silent).
  if ! thermograph_openbao_source "$env_name" > "$tmp"; then
    rm -f "$tmp"
    return 1
  fi

  # An empty render must never reach $out. The source function already refuses a
  # zero-key result, so this is a second line of defence rather than the only one:
  # a truncated /etc/thermograph.env is the single worst outcome available here,
  # because thermograph.service uses `EnvironmentFile=-` (missing is NOT fatal) and
  # the app self-generates AUTH_SECRET and the VAPID pair when they are absent. The
  # result would be a green deploy that silently invalidated every session and
  # deleted every push subscription.
  if [ ! -s "$tmp" ]; then
    echo "!! OpenBao render produced an empty file; refusing to write $out" >&2
    rm -f "$tmp"
    return 1
  fi

  local rc=0
  if [ -f "$out" ] && [ -w "$out" ]; then
    cat "$tmp" > "$out" || rc=1
  elif install -m 0640 "$tmp" "$out" 2>/dev/null; then :
  elif sudo install -m 0640 -o "$(id -un)" -g "$(id -gn)" "$tmp" "$out" 2>/dev/null; then :
  else
    echo "!! cannot write $out (need file write access or passwordless sudo)" >&2
    rc=1
  fi

  if [ "$rc" = 0 ] && [ -n "${THERMOGRAPH_SECRETS_ENV_FILE_MIRROR:-}" ]; then
    if ! mkdir -p "$(dirname "$THERMOGRAPH_SECRETS_ENV_FILE_MIRROR")" \
       || ! install -m 0600 "$tmp" "$THERMOGRAPH_SECRETS_ENV_FILE_MIRROR"; then
      echo "!! cannot write mirror at $THERMOGRAPH_SECRETS_ENV_FILE_MIRROR" >&2
      rc=1
    fi
  fi

  rm -f "$tmp"
  return "$rc"
}