#!/usr/bin/env bash
#
# Assert that the environment this project needs is present AND plausible,
# before the thing that needs it starts. Read-only: it measures and it reports.
#
#   bash scripts/check-env.sh                  # check the process environment
#   bash scripts/check-env.sh --file .env      # check a file instead — only the file
#   bash scripts/check-env.sh --quiet          # failures only, for calling from a script
#   bash scripts/check-env.sh --list           # print what is declared, check nothing
#
# Exit codes, because the caller is usually another script deciding whether to
# continue:
#
#   0  every required variable is present, and everything that IS set has the
#      right shape
#   1  problems found — they are listed, grouped, with the source named
#   2  NOTHING WAS CHECKED — the spec is empty, or the source could not be
#      read. This is not a pass and CI must not treat it as one.
#
# All output goes to stderr, so `check-env.sh --quiet` can be called from the
# middle of another script without polluting that script's stdout.
#
# ===========================================================================
# TEMPLATE COPY — configure this before the first run
# ===========================================================================
#
# Copy to `scripts/check-env.sh`, `chmod +x` it, and fill in the SPEC block
# below — one line per variable. Nothing else needs editing.
#
# SPEC ships empty and the script exits 2 until it has an entry. An empty spec
# would examine nothing and have nothing to report, and the natural way to
# print that is "ok" — a green result from a checker that measured nothing.
# That is the worst possible output, because the whole value of this script is
# that everything downstream stops re-checking and starts trusting it.
#
# There are no default variable names, deliberately, for the reason release.sh
# gives at length: a list inherited from another project is a list of the wrong
# names. It passes — every variable it knows about really is set, in your shell,
# by that other project's tooling — while every variable this project actually
# reads goes unexamined. A checker that is confidently green about the wrong
# environment is worse than no checker.
#
# Assumes: bash, coreutils. It reads nothing from the repository, and the only
# thing it shells out to is `tr` for case folding — no docker, no git, no
# network client — so it runs unchanged inside a scratch container.
#
# ## Why this exists
#
# Absence is the cheap failure. A variable that is not set fails at the first
# line that reads it, loudly, usually before the process finishes starting.
#
# The expensive failure is a variable that is present and the wrong shape,
# because nothing refuses to start:
#
#   PORT=3000/tcp          a compose port mapping pasted into a port field
#   DATABASE_URL=postgres://localhost/app
#                          right on a laptop; inside a container `localhost`
#                          is the container, and the database is elsewhere
#   NODE_ENV=Production    matches no `=== "production"` anywhere, so every
#                          branch takes its development arm in production
#   JWT_SECRET=devsecret   the eight characters someone typed to get the dev
#                          server up, now signing real sessions
#   API_URL=https://api.example.com/
#                          one trailing slash; every joined path is `//v1/...`
#
# All five start. Most of them serve traffic. That is nearly the whole of
# "works on my machine, broken in the container": not a missing variable — a
# variable with the wrong shape, in an environment nobody ever compared against
# the one it was written for. So this checks SHAPE, not just presence.
#
# ## Every problem, in one pass
#
# The alternative is the loop everyone knows: start, crash on one variable, fix
# it, start, crash on the next. Each turn of that loop costs a full boot, and
# on a deploy target it costs a rollback. So nothing here short-circuits — the
# whole spec is evaluated and the report names everything that is wrong at
# once, grouped, with optional-and-absent shown separately because it is not a
# problem and must never read as one.
#
# ## Secrets are measured, never printed
#
# Anything whose name looks like a credential, and anything declared with the
# `secret-min-length` kind, is reported as "set, N characters" and never as its
# value — including inside failure messages, which is where a careless
# validator leaks: the whole point of a failure message is to show you what it
# saw. CI keeps its logs for months and shows them to everyone with read access
# to the repository, so a validator that echoes what it validated has published
# the credential to a wider audience than the breach it was guarding against.
#
# The name pattern errs toward over-matching. A false positive costs one
# unprinted value; a false negative costs a credential in a log.
#
# ## Where to call it
#
# From the container entrypoint before `exec`, from `predev`/`prestart`, and
# from CI before the deploy step. A checker nobody calls is decoration, and the
# environment is exactly the thing that differs between the place you tested
# and the place it broke.
#
# ## What it deliberately does not do
#
# It does not connect to anything. It never opens DATABASE_URL or curls
# API_URL. Reachability depends on a VPN, a network namespace and a machine
# that may not be this one, so a reachability check fails on laptops for
# reasons that are nobody's fault — and a check that cries wolf gets an
# `|| true` appended within a week, taking the shape checks down with it. This
# says the values are plausible. It does not say the services are up.
#
# It does not write, export, repair or default anything, so there is no
# --dry-run: there is no outward-facing act to preview. A checker that fixes
# what it finds is one you stop reading, and then it starts inventing the
# values that reach production.
#
# It does not merge sources. With --file it reads the file and the process
# environment is not consulted at all, which is the point: a variable that is
# set in your shell and missing from the .env is precisely the bug you came
# here to find, and merging hides it.
#
# It does not know your framework and never guesses a name. Every variable it
# checks is one you declared.

set -uo pipefail

# ---------------------------------------------------------------------------
# Snapshot the environment before this script assigns a single variable of its
# own. Nothing above this line may set a variable.
#
# `${!name}` reads a SHELL variable, and this script's own — QUIET, VALUE,
# SOURCE_LABEL, NAME_WIDTH, LIST_ONLY — live in the same namespace as the
# environment it is measuring. Read live rather than from a snapshot, the
# checker measures itself, in both directions and both are wrong:
#
#   NAME_WIDTH  declared in SPEC, unset in a scrubbed environment, reported
#               "ok — present and the right shape: 14" and exited 0. Green for
#               a variable nobody set, which is the one failure this file's
#               header spends forty lines arguing is worse than no checker.
#   QUIET=yes   exported by the caller, reported "set, but empty" and exited 1,
#               because the assignment below overwrote the value while keeping
#               the export attribute. A failure nobody caused, on a variable
#               that was correct.
#
# Taken here the snapshot is the environment as this process received it, and
# nothing this script does afterwards can alter what it reports. The _CE_ prefix
# is reserved from SPEC below so the snapshot cannot collide in its turn.
# ---------------------------------------------------------------------------
# `compgen` is a bash builtin, but it belongs to programmable completion and a
# bash built with --disable-progcomp does not have it. Without this the snapshot
# would come back empty and every declared variable would be reported missing:
# a confident, total, wrong answer. Refuse instead — that is a reason this
# script could not measure the environment, which is what exit 2 means. die()
# is not defined this early, so the message is written out longhand.
if ! type -t compgen >/dev/null 2>&1; then
  printf '\033[1mcheck-env:\033[0m this bash has no `compgen`, so the environment cannot be\n' >&2
  printf '\033[1mcheck-env:\033[0m read reliably and nothing was checked. That is not a pass.\n' >&2
  exit 2
fi

_CE_ENV_NAMES=()
_CE_ENV_VALS=()
while IFS= read -r _CE_N; do
  [ -n "$_CE_N" ] || continue
  # `export FOO` with no value is exported-but-unset: it is not in a child's
  # environment either, so it is absence rather than an empty value. `+x`
  # keeps set-to-empty, which `docker run -e FOO` produces and which is a
  # different bug from unset.
  [ -n "${!_CE_N+x}" ] || continue
  _CE_ENV_NAMES+=("$_CE_N")
  _CE_ENV_VALS+=("${!_CE_N}")
done <<<"$(compgen -e)"
unset _CE_N

# ---------------------------------------------------------------------------
# SPEC — the variables this project needs. One line each, then delete this
# banner. Adding a variable later is a one-line edit and nothing else.
#
#   "NAME|required|kind|what breaks when it is missing or wrong"
#
# The description is not documentation. It is the sentence printed next to the
# failure at 03:00, so write the CONSEQUENCE ("sessions cannot be signed, every
# login 500s") rather than a restatement of the name ("the JWT secret").
#
# required | optional  — spelled exactly. A typo is refused rather than read as
#                        "optional", because silently downgrading a required
#                        variable is the one mistake this script cannot survive.
#
# Kinds:
#   nonempty             any non-empty string; for values whose shape is
#                        genuinely unknowable. Not a lazy default — it is the
#                        honest one, and it still catches unset and empty.
#   int                  a whole number
#   int:MIN..MAX         a whole number within bounds, inclusive
#   port                 1-65535
#   url                  scheme://host[...]; rejects a bare `host:5432`
#   path                 a filesystem path; existence is reported only when the
#                        source is this machine's own environment
#   one-of:a,b,c         exactly one of these, compared case-sensitively
#   secret-min-length:N  at least N characters; the value is never printed, and
#                        it is checked against well-known placeholders
#
# Examples of the FORM. Delete them — they are shapes, not your variables:
#
#   "DATABASE_URL|required|url|nothing can read or write; every request 500s"
#   "PORT|optional|port|the server binds its own default, which the proxy is not pointed at"
#   "NODE_ENV|required|one-of:development,production,test|the wrong branch of every environment check"
#   "SESSION_SECRET|required|secret-min-length:32|sessions are forgeable"
#   "UPLOAD_DIR|optional|path|uploads land somewhere nothing serves and nothing backs up"
# ---------------------------------------------------------------------------

SPEC=(
  # --- Always. Wrong here and the site is wrong for everybody. ---
  "NODE_ENV|required|one-of:development,production,test|CSP relaxes in dev and the HTTP-to-HTTPS redirect only fires in production; the wrong value ships dev CSP to the public origin, or redirects a local dev server into a loop"
  "SERVER_PORT|required|port|Express binds 3001 by default and the reverse proxy in front of nebula is pointed at whatever this says; a mismatch is a site that is running and unreachable"
  "CORS_ORIGIN|required|url|the production origin, https://queuenorth.com, with NO trailing slash — a slash matches no real browser origin and silently blocks every cross-origin form post while the server logs nothing wrong. Both public hostnames reach the same container, so the site's own forms are same-origin and unaffected; this is about anything that is not"
  "LOG_LEVEL|optional|one-of:error,warn,info,debug|defaults to info. At error you lose the request log, which is the only record of traffic this project keeps"
  "RATE_LIMIT_PER_MINUTE|optional|int:1..1000|defaults to 5 per IP across all of /api. Unset is fine; set to something huge and the two POST endpoints are open to a bot overnight"

  # --- Anti-abuse. The only thing between two open POST endpoints and a bot. ---
  "RECAPTCHA_ENABLED|required|one-of:true,false|anything other than the literal string true disables verification silently. Declared required so that switching it off is a decision somebody typed, not a variable somebody forgot"
  "RECAPTCHA_SECRET_KEY|optional|secret-min-length:32|required in practice whenever RECAPTCHA_ENABLED=true — without it every verification fails open and the forms have no protection at all. Optional here only because this script cannot express the conditional"
  "RECAPTCHA_MIN_SCORE|optional|nonempty|defaults to 0.5. A float, so it is not range-checked here; set it to 0 and every bot passes"
  "VITE_RECAPTCHA_SITE_KEY|optional|nonempty|BUILD TIME, not runtime — Vite inlines it into dist/. Absent at build and the widget never loads, and no restart fixes it. It must be the SITE key; the secret key here ships the secret to every visitor"

  # --- CRM forwarding. Which half matters depends on the mode. ---
  "ZOHO_FORWARDING_MODE|required|one-of:webtolead,api|selects which of the two blocks below is actually read. Production is webtolead; the api path is a configured standby. Wrong value and leads are written to SQLite and forwarded nowhere, silently, because the forward is fire-and-forget by design"

  "ZOHO_WEBTOLEAD_ENABLED|optional|one-of:true,false|the on switch for the mode production actually uses. False means no lead reaches the CRM and the visitor still sees success"
  "ZOHO_WEBTOLEAD_URL|optional|url|defaults to the Zoho form endpoint. A wrong host means every forward posts into the void"
  "ZOHO_WEBTOLEAD_XNQSJSDP|optional|secret-min-length:32|the form identifier. Missing or wrong and Zoho rejects the post; leads survive in SQLite and never appear in the CRM"
  "ZOHO_WEBTOLEAD_XMIWTLD|optional|secret-min-length:32|the second form identifier, same consequence"
  "ZOHO_WEBTOLEAD_ACTION_TYPE|optional|nonempty|base64 for the target module. Defaults to Leads; wrong and records land in the wrong module"
  "ZOHO_WEBTOLEAD_RETURN_URL|optional|nonempty|the literal string null is correct here — server-to-server, nothing redirects. Not url-checked for that reason"
  "ZOHO_WEBTOLEAD_ZC_GAD|optional|nonempty|Zoho ad-tracking field, legitimately empty"

  "ZOHO_ENABLED|optional|one-of:true,false|the on switch for the OAuth/REST standby path. Irrelevant while the mode is webtolead"
  "ZOHO_CASES_ENABLED|optional|one-of:true,false|forwards support requests as Zoho Cases. Off means support tickets exist only in SQLite, where nobody is looking at them"
  "ZOHO_API_DOMAIN|optional|url|the API host for the standby path. Datacenter-specific"
  "ZOHO_ACCOUNTS_DOMAIN|optional|url|the OAUTH TOKEN host, which is a DIFFERENT domain from the API host. Pointing this at the API domain is the bug that shipped once and failed every token refresh in production"
  "ZOHO_CLIENT_ID|optional|nonempty|standby path only"
  "ZOHO_CLIENT_SECRET|optional|secret-min-length:16|standby path only"
  "ZOHO_REFRESH_TOKEN|optional|secret-min-length:16|standby path only. Grants write access to the CRM"
)

# ---------------------------------------------------------------------------
# Redaction. See "Secrets are measured, never printed" above.
#
# Matched case-insensitively against the whole variable name, so KEY catches
# API_KEY, KEYCLOAK_SECRET and MONKEY_HOST alike. The last is a false positive
# and costs nothing: its value is described rather than shown.
# ---------------------------------------------------------------------------
SECRET_NAME_PATTERN='SECRET|TOKEN|PASSWORD|PASSWD|PWD|CREDENTIAL|PRIVATE|SALT|SIGNATURE|SIGNING|AUTH|KEY|DSN|COOKIE'

# Values a `secret-min-length` variable must not be, compared in lower case and
# never echoed. These are the strings typed to make the dev server start, which
# then travel to production inside a copied .env and satisfy every length rule.
PLACEHOLDER_SECRETS='changeme change-me change_me changethis secret mysecret supersecret password passwd hunter2 test testing example placeholder todo tbd xxx xxxx admin dev devsecret development your-secret-here your_secret_here notasecret 123456 12345678 abc123'

# Redaction applies to NAMES read out of a file too, not only to values.
#
# A multi-line secret pasted into a .env — a PEM body, a wrapped base64 blob —
# has continuation lines carrying '=' padding, so `KEY=VALUE` parsing splits one
# into a "name" and a "value" and the name is a slice of the credential. Every
# message that prints a name out of a file therefore prints its LENGTH once it
# is longer than any name could plausibly be, which is the same rule values
# already follow. 40 covers the longest real variable names (the framework
# ones reach the low forties); a 64-column PEM line does not come close.
NAME_PRINT_MAX=40

say() { printf '\033[1mcheck-env:\033[0m %s\n' "$*" >&2; }

# die is 2, not the 1 its counterpart in release.sh uses: everything that calls
# it is a reason this script could not measure the environment, and a caller
# must be able to tell "your configuration is wrong" from "I never found out".
die() { printf '\033[1mcheck-env:\033[0m %s\n' "$*" >&2; exit 2; }

usage() {
  say "usage: check-env.sh [--file PATH] [--quiet] [--list] [--help]"
  say "  --file PATH   check that file instead of the process environment"
  say "  --quiet, -q   print only failures (exit code still says everything)"
  say "  --list        print the declared spec and check nothing"
  say "  --help, -h    this message"
}

trim() {
  local s="$1"
  s="${s#"${s%%[![:space:]]*}"}"
  s="${s%"${s##*[![:space:]]}"}"
  printf '%s' "$s"
}

SOURCE_FILE=""
QUIET=""
LIST_ONLY=""

while [ $# -gt 0 ]; do
  case "$1" in
    --file)     shift; [ $# -gt 0 ] || die "--file needs a path."; SOURCE_FILE="$1" ;;
    --file=*)   SOURCE_FILE="${1#--file=}"; [ -n "$SOURCE_FILE" ] || die "--file needs a path." ;;
    --quiet|-q) QUIET="yes" ;;
    --list)     LIST_ONLY="yes" ;;
    -h|--help)  usage; exit 0 ;;
    *)          usage; die "unknown argument '$1'." ;;
  esac
  shift
done

# ---------------------------------------------------------------------------
# Read the spec, and refuse anything ambiguous.
#
# A malformed spec entry is a configuration error in this script, not a finding
# about the environment, so it exits 2 and reports nothing about the variables:
# a partial report from a spec that is half-understood is the same lie as a
# green one from an empty spec.
# ---------------------------------------------------------------------------

if [ "${#SPEC[@]}" -eq 0 ]; then
  say "SPEC is empty, so nothing was checked. That is not a pass."
  say ""
  say "This is a fresh template copy: declare the variables this project reads"
  say "in the SPEC block near the top of this file, one line each —"
  say '  "DATABASE_URL|required|url|nothing can read or write; every request 500s"'
  die "then run this again."
fi

SPEC_NAME=()
SPEC_REQ=()
SPEC_KIND=()
SPEC_PARAM=()
SPEC_DESC=()
NAME_WIDTH=4

entry_no=0
for entry in "${SPEC[@]}"; do
  entry_no=$((entry_no + 1))

  # A description may legitimately contain '|', so read takes only four fields
  # and the fourth keeps the rest.
  IFS='|' read -r f_name f_req f_kind f_desc <<<"$entry"

  f_name=$(trim "${f_name:-}")
  f_req=$(trim "${f_req:-}")
  f_kind=$(trim "${f_kind:-}")
  f_desc=$(trim "${f_desc:-}")

  [ -n "$f_name" ] && [ -n "$f_req" ] && [ -n "$f_kind" ] && [ -n "$f_desc" ] \
    || die "SPEC entry ${entry_no} is not NAME|required|kind|description: '${entry}'"

  # The shell cannot export a name it cannot parse, so a name that fails this
  # could never have been set in the first place and every run would report it
  # missing forever.
  [[ "$f_name" =~ ^[A-Za-z_][A-Za-z0-9_]*$ ]] \
    || die "SPEC entry ${entry_no}: '${f_name}' is not a usable variable name."

  # The environment snapshot has to live somewhere, and a variable it could
  # collide with is one this script would measure against itself. Refused
  # rather than measured wrong.
  case "$f_name" in
    _CE_*) die "SPEC entry ${entry_no}: '${f_name}' uses the _CE_ prefix, which this script reserves for the environment snapshot it takes before it defines anything. Rename the variable, or rename the snapshot at the top of this file." ;;
  esac

  case "$f_req" in
    required|optional) : ;;
    *) die "SPEC entry ${entry_no} (${f_name}): expected 'required' or 'optional', got '${f_req}'. Spelling matters here — see the SPEC block." ;;
  esac

  kind_name="${f_kind%%:*}"
  kind_param=""
  case "$f_kind" in *:*) kind_param="${f_kind#*:}" ;; esac

  case "$kind_name" in
    nonempty|url|port|path)
      [ -z "$kind_param" ] || die "SPEC entry ${entry_no} (${f_name}): kind '${kind_name}' takes no ':' argument." ;;
    int)
      if [ -n "$kind_param" ]; then
        [[ "$kind_param" =~ ^[+-]?[0-9]+\.\.[+-]?[0-9]+$ ]] \
          || die "SPEC entry ${entry_no} (${f_name}): int bounds must look like 1..100, got '${kind_param}'."
      fi ;;
    one-of)
      [ -n "$kind_param" ] || die "SPEC entry ${entry_no} (${f_name}): one-of needs a comma-separated list, e.g. one-of:development,production." ;;
    secret-min-length)
      [[ "$kind_param" =~ ^[0-9]+$ ]] && [ "$kind_param" -gt 0 ] \
        || die "SPEC entry ${entry_no} (${f_name}): secret-min-length needs a positive number, e.g. secret-min-length:32." ;;
    *)
      die "SPEC entry ${entry_no} (${f_name}): unknown kind '${kind_name}'. Valid: nonempty, int, port, url, path, one-of:a,b, secret-min-length:N." ;;
  esac

  # A name declared twice gets two descriptions, and the report would print
  # both — one of which is now out of date and neither of which is marked.
  for existing in ${SPEC_NAME[@]+"${SPEC_NAME[@]}"}; do
    [ "$existing" = "$f_name" ] && die "SPEC declares ${f_name} twice. Keep one line."
  done

  SPEC_NAME+=("$f_name")
  SPEC_REQ+=("$f_req")
  SPEC_KIND+=("$kind_name")
  SPEC_PARAM+=("$kind_param")
  SPEC_DESC+=("$f_desc")

  [ "${#f_name}" -gt "$NAME_WIDTH" ] && NAME_WIDTH="${#f_name}"
done

if [ -n "$LIST_ONLY" ]; then
  say "declared in SPEC — nothing was checked:"
  for (( i = 0; i < ${#SPEC_NAME[@]}; i++ )); do
    kind="${SPEC_KIND[$i]}"
    [ -n "${SPEC_PARAM[$i]}" ] && kind="${kind}:${SPEC_PARAM[$i]}"
    printf '    %-*s  %-8s  %-22s  %s\n' \
      "$NAME_WIDTH" "${SPEC_NAME[$i]}" "${SPEC_REQ[$i]}" "$kind" "${SPEC_DESC[$i]}" >&2
  done
  exit 0
fi

# ---------------------------------------------------------------------------
# Display. Every message that mentions a value goes through show(), and that is
# the only place the redaction rule is enforced — so nothing else in this
# script may interpolate a value into a message. If you add a check, use it.
# ---------------------------------------------------------------------------

is_secret() {
  case "$2" in secret-min-length) return 0 ;; esac
  local upper
  upper=$(printf '%s' "$1" | tr '[:lower:]' '[:upper:]')
  [[ "$upper" =~ $SECRET_NAME_PATTERN ]]
}

show() {
  local name="$1" kind="$2" value="$3"

  if is_secret "$name" "$kind"; then
    printf 'set, %d characters (value withheld)' "${#value}"
    return 0
  fi

  case "$kind" in
    url)
      # Scheme and host are what you need to spot the wrong environment; the
      # path and query are where webhook and signed-URL secrets live, so they
      # are summarised rather than shown.
      local rest authority tail=""
      case "$value" in
        *://*)
          rest="${value#*://}"
          authority="${rest%%/*}"
          authority="${authority%%\?*}"
          case "$authority" in *@*) authority="***@${authority##*@}" ;; esac
          case "$rest" in */*|*\?*) tail="/…" ;; esac
          printf '%s://%s%s' "${value%%://*}" "$authority" "$tail"
          return 0 ;;
      esac
      ;;
    # Bounded, enumerable and not credential-shaped by construction. `literal`
    # is the mode a failure message asks for when the value IS the finding —
    # a port of '3000/tcp' cannot be explained without quoting it.
    int|port|one-of|path|literal) : ;;
    *)
      # Unknown shape, so nothing is known about what might be inside it.
      printf 'set, %d characters' "${#value}"
      return 0 ;;
  esac

  if [ "${#value}" -gt 60 ]; then
    printf '%s…' "${value:0:59}"
  else
    printf '%s' "$value"
  fi
}

# ---------------------------------------------------------------------------
# Load the source.
# ---------------------------------------------------------------------------

FILE_KEYS=()
FILE_VALS=()
FILE_LINES=()
FILE_BAD=()
FILE_NOTES=()

load_file() {
  local path="$1" lineno=0 line trimmed key val

  # Redirection, not `cat "$path" |`: a piped while-loop runs in a subshell and
  # every array appended inside it is discarded at the `done`.
  while IFS= read -r line || [ -n "$line" ]; do
    lineno=$((lineno + 1))

    case "$line" in
      *$'\r')
        line="${line%$'\r'}"
        FILE_NOTES+=("line ${lineno}|has a CRLF line ending; most loaders keep the carriage return, making the value one invisible character longer than it looks") ;;
    esac

    trimmed=$(trim "$line")
    case "$trimmed" in ''|'#'*) continue ;; esac

    case "$trimmed" in
      export\ *|export$'\t'*)
        trimmed=$(trim "${trimmed#export}")
        FILE_NOTES+=("line ${lineno}|uses 'export'; a shell sourcing this file is fine, but docker --env-file reads the name as 'export NAME'") ;;
    esac

    case "$trimmed" in
      *=*) key="${trimmed%%=*}"; val="${trimmed#*=}" ;;
      *)   FILE_BAD+=("line ${lineno}|no '=', so it sets nothing at all"); continue ;;
    esac

    if [[ ! "$key" =~ ^[A-Za-z_][A-Za-z0-9_]*$ ]]; then
      if [[ "$(trim "$key")" =~ ^[A-Za-z_][A-Za-z0-9_]*$ ]]; then
        FILE_BAD+=("line ${lineno}|has spaces around '='; outside a shell those become part of the name and of the value")
      elif [ "${#key}" -gt "$NAME_PRINT_MAX" ]; then
        FILE_BAD+=("line ${lineno}|has ${#key} characters before its '=', so that is not a name and nothing can read it; the text is withheld in case this is one line of a wrapped multi-line secret")
      else
        FILE_BAD+=("line ${lineno}|'${key}' is not a usable variable name, so nothing can read it")
      fi
      continue
    fi

    # Quotes are stripped here because that is what dotenv-style loaders do —
    # but docker --env-file does not, so the two see different values. Said out
    # loud rather than resolved, because only the operator knows which loader
    # will read this file.
    case "$val" in
      \"*\"|\'*\')
        val="${val:1:${#val}-2}"
        FILE_NOTES+=("${key}|is quoted; dotenv-style loaders strip the quotes and docker --env-file keeps them, so the two disagree about this value") ;;
    esac

    case "$val" in
      *'${'*|*'$('*)
        FILE_NOTES+=("${key}|contains a \$ expansion; dotenv-style loaders interpolate it and docker --env-file passes it through literally") ;;
    esac

    local j
    for (( j = 0; j < ${#FILE_KEYS[@]}; j++ )); do
      if [ "${FILE_KEYS[$j]}" = "$key" ]; then
        FILE_NOTES+=("${key}|is set twice (lines ${FILE_LINES[$j]} and ${lineno}); loaders disagree about which one wins")
        break
      fi
    done

    FILE_KEYS+=("$key")
    FILE_VALS+=("$val")
    FILE_LINES+=("$lineno")
  done < "$path"
}

if [ -n "$SOURCE_FILE" ]; then
  # Refused rather than fallen back on. You asked about a file; answering about
  # the process environment instead would be a confident pass from a source you
  # did not name — see status.sh on why a tool that answers about the wrong
  # thing is worse than one that answers nothing.
  [ -e "$SOURCE_FILE" ] || die "--file '${SOURCE_FILE}' does not exist. Refusing to check the process environment instead."
  [ -f "$SOURCE_FILE" ] || die "--file '${SOURCE_FILE}' is not a regular file."
  [ -r "$SOURCE_FILE" ] || die "--file '${SOURCE_FILE}' is not readable by this user."
  load_file "$SOURCE_FILE"
  SOURCE_LABEL="${SOURCE_FILE}"
else
  SOURCE_LABEL="the process environment"
fi

# The empty string means "not set here". Callers must not read it as "set to
# nothing" — FOUND says which.
FOUND=""
VALUE=""

# The locals are prefixed for the same reason the snapshot is: `lookup`'s own
# `want` and `j` would shadow a SPEC entry of either name, and this is the one
# function that resolves a variable name at runtime.
lookup() {
  local _ce_want="$1" _ce_j
  FOUND=""
  VALUE=""

  if [ -n "$SOURCE_FILE" ]; then
    # No break: the last assignment wins, which is what a loader reading the
    # file top to bottom into a map does.
    for (( _ce_j = 0; _ce_j < ${#FILE_KEYS[@]}; _ce_j++ )); do
      if [ "${FILE_KEYS[$_ce_j]}" = "$_ce_want" ]; then FOUND="yes"; VALUE="${FILE_VALS[$_ce_j]}"; fi
    done
  else
    # The snapshot taken at the top, never the live variable: see the reasoning
    # there. A name absent from the snapshot was absent from the environment,
    # whatever this script may since have set in its own namespace.
    for (( _ce_j = 0; _ce_j < ${#_CE_ENV_NAMES[@]}; _ce_j++ )); do
      if [ "${_CE_ENV_NAMES[$_ce_j]}" = "$_ce_want" ]; then
        FOUND="yes"; VALUE="${_CE_ENV_VALS[$_ce_j]}"; break
      fi
    done
  fi
}

# ---------------------------------------------------------------------------
# Shape checks.
#
# check_shape prints zero or more lines, each 'fail:<reason>' or 'note:<reason>'
# — a protocol rather than array appends because it is called in a command
# substitution, and an array appended inside a subshell is gone at the closing
# paren.
# ---------------------------------------------------------------------------

check_shape() {
  local name="$1" kind="$2" param="$3" value="$4"

  case "$value" in
    ' '*|$'\t'*) printf 'fail:begins with whitespace, which is part of the value everywhere except a shell\n' ;;
  esac
  case "$value" in
    *' '|*$'\t') printf 'fail:ends with whitespace, which is part of the value and breaks every comparison against it\n' ;;
  esac

  case "$kind" in
    url|port|int|one-of|path)
      case "$value" in
        *$'\n'*) printf 'fail:contains a newline, so nothing downstream will parse it\n'; return 0 ;;
      esac ;;
  esac

  case "$kind" in
    nonempty)
      # Presence and non-emptiness are the same test, already done by the
      # caller. Reaching here means it passed; there is nothing else to know.
      : ;;

    int)
      if [[ ! "$value" =~ ^[+-]?[0-9]+$ ]]; then
        printf 'fail:is not a whole number: %s\n' "$(show "$name" "$kind" "$value")"
        return 0
      fi
      local n="${value#+}"
      # Bash arithmetic is 64-bit and errors past it, so an absurd number is
      # rejected by length before anything tries to compare it.
      if [ "${#n}" -gt 18 ]; then
        printf 'fail:has %d digits; nothing downstream will read that as a number\n' "${#n}"
        return 0
      fi
      if [ -n "$param" ]; then
        local lo="${param%%..*}" hi="${param##*..}"
        if [ "$n" -lt "${lo#+}" ] || [ "$n" -gt "${hi#+}" ]; then
          # Through show(), not the bare value: an out-of-range number under a
          # credential-shaped name — TOTP_KEY, AUTH_TOKEN_TTL — is still a
          # credential, and this is a failure message, which is precisely where
          # the header says a careless validator leaks. The bounds come from the
          # spec, so they are always safe to print.
          printf 'fail:is %s, outside the allowed %s..%s\n' \
            "$(show "$name" "$kind" "$value")" "${lo#+}" "${hi#+}"
        fi
      fi ;;

    port)
      case "$value" in
        *://*) printf 'fail:is a URL, not a port number: %s\n' "$(show "$name" url "$value")"; return 0 ;;
        */*)   printf 'fail:looks like a compose port mapping (%s); a port field takes the number alone\n' "$(show "$name" literal "$value")"; return 0 ;;
      esac
      if [[ ! "$value" =~ ^[0-9]{1,5}$ ]] || [ "$value" -lt 1 ] || [ "$value" -gt 65535 ]; then
        printf 'fail:is not a port; ports are 1-65535\n'
        return 0
      fi ;;

    url)
      case "$value" in
        *://*) : ;;
        *)
          printf 'fail:has no scheme — %s is a host, not a URL; write it as scheme://host\n' "$(show "$name" literal "$value")"
          return 0 ;;
      esac

      local scheme="${value%%://*}" rest="${value#*://}" authority
      if [[ ! "$scheme" =~ ^[A-Za-z][A-Za-z0-9+.-]*$ ]]; then
        printf 'fail:has a scheme that is not a scheme\n'
        return 0
      fi

      authority="${rest%%/*}"
      authority="${authority%%\?*}"
      case "$authority" in *@*) authority="${authority##*@}" ;; esac

      if [ -z "$authority" ]; then
        printf 'fail:has no host between // and the path\n'
        return 0
      fi
      case "$authority" in
        *' '*) printf 'fail:has a space in the host\n'; return 0 ;;
      esac

      case "$authority" in
        localhost|localhost:*|127.0.0.1|127.0.0.1:*|0.0.0.0|0.0.0.0:*|'[::1]'|'[::1]':*)
          printf 'note:points at %s — correct on a laptop; inside a container that is the container itself, not the host\n' "$authority" ;;
        host.docker.internal*)
          printf 'note:points at host.docker.internal, which resolves on Docker Desktop and not on a Linux daemon without an extra_hosts entry\n' ;;
      esac

      case "$value" in
        */) printf 'note:ends with a slash, so anything joining a path onto it produces a double slash\n' ;;
      esac ;;

    path)
      case "$value" in
        '~'*) printf 'fail:starts with ~, and nothing expands a tilde inside an environment variable — a process reading this opens a directory literally named ~\n' ;;
      esac
      case "$value" in
        /*) : ;;
        *)  printf 'note:is relative, so it resolves against the working directory of whatever starts the process rather than the one you typed it in\n' ;;
      esac
      # Existence is a fact about THIS machine. Checking it against a file that
      # describes another machine would report a fault that is not one, so in
      # --file mode it is not checked and the report says so rather than
      # leaving a silent gap.
      if [ -z "$SOURCE_FILE" ] && [ ! -e "$value" ]; then
        printf 'note:does not exist on this machine (this may be correct if the volume is mounted later)\n'
      fi ;;

    one-of)
      local rest="$param" opt matched="" ci_match=""
      local lower_value lower_opt
      lower_value=$(printf '%s' "$value" | tr '[:upper:]' '[:lower:]')
      while [ -n "$rest" ]; do
        opt="${rest%%,*}"
        [ "$value" = "$opt" ] && matched="yes"
        lower_opt=$(printf '%s' "$opt" | tr '[:upper:]' '[:lower:]')
        [ "$lower_value" = "$lower_opt" ] && ci_match="$opt"
        case "$rest" in *,*) rest="${rest#*,}" ;; *) rest="" ;; esac
      done
      if [ -z "$matched" ]; then
        if [ -n "$ci_match" ]; then
          printf 'fail:is %s, and the comparison is case-sensitive: write %s\n' "$(show "$name" one-of "$value")" "$ci_match"
        else
          printf 'fail:is %s; allowed: %s\n' "$(show "$name" one-of "$value")" "${param//,/, }"
        fi
      fi ;;

    secret-min-length)
      # Length is the only property reported. Nothing below prints the value,
      # and the comparison below pipes it to `tr` rather than passing it as an
      # argument, so it never appears in this process's command line either.
      if [ "${#value}" -lt "$param" ]; then
        printf 'fail:is %d characters and the spec requires %d (value withheld)\n' "${#value}" "$param"
      fi
      local lower placeholder
      lower=$(printf '%s' "$value" | tr '[:upper:]' '[:lower:]')
      for placeholder in $PLACEHOLDER_SECRETS; do
        if [ "$lower" = "$placeholder" ]; then
          printf 'fail:is a well-known placeholder, not a secret — anyone can guess it (value withheld)\n'
          break
        fi
      done ;;
  esac
}

# ---------------------------------------------------------------------------
# Measure everything, then report. Nothing exits early: one run must name every
# problem, or fixing them costs one restart each.
# ---------------------------------------------------------------------------

MISSING=()
MALFORMED=()
NOTES=()
OPT_ABSENT=()
PRESENT_OK=()

for (( i = 0; i < ${#SPEC_NAME[@]}; i++ )); do
  name="${SPEC_NAME[$i]}"
  req="${SPEC_REQ[$i]}"
  kind="${SPEC_KIND[$i]}"
  param="${SPEC_PARAM[$i]}"
  desc="${SPEC_DESC[$i]}"

  lookup "$name"

  if [ -z "$FOUND" ]; then
    if [ "$req" = "required" ]; then
      MISSING+=("${name}|${desc}")
    else
      OPT_ABSENT+=("${name}|${desc}")
    fi
    continue
  fi

  if [ -z "$VALUE" ]; then
    if [ "$req" = "required" ]; then
      MISSING+=("${name}|set, but empty — ${desc}")
    else
      # Set-to-empty is not unset, and code tests it both ways: a truthiness
      # check sees nothing, a key-presence check sees it. Reported so the
      # ambiguity is the operator's to resolve rather than this script's.
      OPT_ABSENT+=("${name}|${desc}")
      NOTES+=("${name}|is set to the empty string, which is not the same as unset to code that checks whether the key is present")
    fi
    continue
  fi

  findings=$(check_shape "$name" "$kind" "$param" "$VALUE")
  had_fail=""

  while IFS= read -r rline; do
    [ -n "$rline" ] || continue
    case "$rline" in
      fail:*) MALFORMED+=("${name}|${rline#fail:}"); had_fail="yes" ;;
      note:*) NOTES+=("${name}|${rline#note:}") ;;
    esac
  done <<<"$findings"

  [ -n "$had_fail" ] || PRESENT_OK+=("${name}|$(show "$name" "$kind" "$VALUE")")
done

if [ -n "$SOURCE_FILE" ]; then
  # Only for a file. The process environment carries hundreds of variables from
  # the shell, the init system and every tool that ever exported one, so
  # "undeclared" there would be noise; in a file every line was written on
  # purpose, and one that matches nothing in the spec is usually a typo in a
  # name — the thing that makes people swear the value is right there.
  for (( j = 0; j < ${#FILE_KEYS[@]}; j++ )); do
    fkey="${FILE_KEYS[$j]}"
    known=""
    for name in ${SPEC_NAME[@]+"${SPEC_NAME[@]}"}; do
      [ "$name" = "$fkey" ] && known="yes" && break
    done
    if [ -z "$known" ]; then
      if [ "${#fkey}" -gt "$NAME_PRINT_MAX" ]; then
        FILE_NOTES+=("line ${FILE_LINES[$j]}|sets a ${#fkey}-character name that is not declared in SPEC and is too long to be a name at all; the text is withheld in case this is one line of a wrapped multi-line secret")
      else
        FILE_NOTES+=("${fkey}|is set on line ${FILE_LINES[$j]} but is not declared in SPEC — a misspelled name, or a spec that has fallen behind")
      fi
    fi
  done
fi

group() {
  local heading="$1"; shift
  [ $# -gt 0 ] || return 0
  say ""
  say "$heading"
  local e
  for e in "$@"; do
    printf '    %-*s  %s\n' "$NAME_WIDTH" "${e%%|*}" "${e#*|}" >&2
  done
}

n_missing="${#MISSING[@]}"
n_malformed="${#MALFORMED[@]}"
n_badlines="${#FILE_BAD[@]}"
n_problems=$(( n_missing + n_malformed + n_badlines ))

# `${arr[@]+"${arr[@]}"}` throughout: under `set -u` a plain "${arr[@]}" on an
# empty array is an error in bash before 4.4, and macOS still ships 3.2.
if [ -z "$QUIET" ] || [ "$n_problems" -gt 0 ]; then
  say "source: ${SOURCE_LABEL}"
  if [ -n "$SOURCE_FILE" ]; then
    say "        the process environment was NOT consulted, on purpose."
  fi
fi

if [ -z "$QUIET" ]; then
  group "ok — present and the right shape:" ${PRESENT_OK[@]+"${PRESENT_OK[@]}"}
  group "optional, not set — this is fine:" ${OPT_ABSENT[@]+"${OPT_ABSENT[@]}"}
  group "worth knowing — not failures:" ${NOTES[@]+"${NOTES[@]}"}

  # Kept apart from the value notes above: these are facts about how the FILE
  # is written, and they apply to whichever loader reads it rather than to any
  # one value being wrong.
  if [ -n "$SOURCE_FILE" ]; then
    group "about ${SOURCE_FILE} itself:" ${FILE_NOTES[@]+"${FILE_NOTES[@]}"}
  fi

  if [ -n "$SOURCE_FILE" ]; then
    for (( i = 0; i < ${#SPEC_KIND[@]}; i++ )); do
      if [ "${SPEC_KIND[$i]}" = "path" ]; then
        say ""
        say "note: path existence was not checked — a file can describe a machine"
        say "      that is not this one. Run without --file to check paths here."
        break
      fi
    done
  fi
fi

group "MALFORMED — set, but the wrong shape:" ${MALFORMED[@]+"${MALFORMED[@]}"}
group "UNREADABLE LINES — these set nothing:" ${FILE_BAD[@]+"${FILE_BAD[@]}"}
group "MISSING — required, not set:" ${MISSING[@]+"${MISSING[@]}"}

if [ "$n_problems" -gt 0 ]; then
  say ""
  say "${n_missing} missing, ${n_malformed} malformed, ${n_badlines} unreadable line(s) in ${SOURCE_LABEL}."
  # Malformed counts as a failure whether the variable was required or
  # optional: not setting an optional variable is a choice, and setting it to
  # something unusable is a mistake that reads as a working configuration.
  say "fix the entries above and run this again — nothing that reads this"
  say "environment can be trusted until then."
  # Exit 1, not die's 2. The difference is the whole contract: 1 means this
  # measured the environment and it is wrong, 2 means it never got far enough
  # to find out. A caller that cannot tell those apart will retry the wrong one.
  exit 1
fi

if [ -z "$QUIET" ]; then
  say ""
  say "ok — ${#PRESENT_OK[@]} set and well-formed, ${#OPT_ABSENT[@]} optional and absent, ${#SPEC_NAME[@]} declared."
  say "shapes only: nothing was connected to, so this says the values are"
  say "plausible, not that the services behind them are up."
fi

exit 0