#!/usr/bin/env bash

# The README describes this repository accurately.
#
# It carries two facts that are cheap to state and easy to leave behind: how
# many contracts there are, and which `panama` subcommands exist. Both had
# already drifted -- the count said 121 when the suite had grown to 125, one day
# after it was written.
#
# A number in prose is not worth much on its own. It is worth something as a
# claim somebody might rely on, and worth nothing once it is wrong, so it is
# either checked or it should not be there.

set -uo pipefail

repo_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
readme="$repo_dir/README.md"
panama="$repo_dir/bin/panama"

findings=()
note() { findings+=("$1"); }
work="$(mktemp -d)"
trap 'rm -rf -- "$work"' EXIT

# ── Verified bootstrap command ───────────────────────────────────────────────

if grep -qE 'bash[[:space:]]+<\(curl[^)]*/raw/branch/main/boot' "$readme"; then
    note 'the README still executes the mutable main-branch bootstrap'
fi
if grep -q '/raw/branch/main/boot' "$readme"; then
    note 'the README still names the mutable main-branch boot URL'
fi

require_bootstrap_occurrences() {
    local pattern="$1" expected="$2" explanation="$3" actual
    actual="$(grep -cE -- "$pattern" "$readme")"
    (( actual == expected )) || note "$explanation"
}

mapfile -t documented_commits < <(
    sed -nE "s/^bootstrap_commit=['\"]?([0-9a-f]{40})['\"]?$/\1/p" "$readme" | sort -u
)
mapfile -t documented_shas < <(
    sed -nE "s/^bootstrap_sha=['\"]?([0-9a-f]{64})['\"]?$/\1/p" "$readme" | sort -u
)

if (( ${#documented_commits[@]} != 1 )); then
    note 'the README does not declare one full lowercase 40-hex bootstrap commit'
else
    documented_commit="${documented_commits[0]}"
    if ! git -C "$repo_dir" cat-file -e "$documented_commit^{commit}" 2>/dev/null; then
        note 'the documented bootstrap commit does not resolve to a repository commit'
    fi
fi

if (( ${#documented_shas[@]} != 1 )); then
    note 'the README does not declare one lowercase 64-hex bootstrap SHA-256'
else
    documented_sha="${documented_shas[0]}"
fi

if [[ -n "${documented_commit:-}" && -n "${documented_sha:-}" ]] \
    && [[ "$(git -C "$repo_dir" show "$documented_commit:boot" 2>/dev/null | sha256sum | cut -d' ' -f1)" != "$documented_sha" ]]; then
    note 'the documented SHA-256 does not match boot in the documented commit'
fi

require_bootstrap_occurrences '^bootstrap_commit=[0-9a-f]{40}$' 2 \
    'the desktop and server commands do not declare the same full bootstrap commit'
require_bootstrap_occurrences '^bootstrap_sha=[0-9a-f]{64}$' 2 \
    'the desktop and server commands do not declare the same full bootstrap SHA-256'
require_bootstrap_occurrences 'https://git\.gbrown\.org/gib/Panama/raw/commit/\$bootstrap_commit/boot' 2 \
    'the desktop and server commands do not both use the commit-addressed boot URL'
require_bootstrap_occurrences '--connect-timeout 10' 2 \
    'the desktop and server commands do not both use the 10-second connect timeout'
require_bootstrap_occurrences '--max-time 30' 2 \
    'the desktop and server commands do not both use the 30-second total timeout'
require_bootstrap_occurrences '--max-filesize 262144' 2 \
    'the desktop and server commands do not both use the 256 KiB response limit'
require_bootstrap_occurrences 'mktemp[[:space:]]+-d' 2 \
    'the desktop and server commands do not both use a private temporary directory'
require_bootstrap_occurrences 'sha256sum[[:space:]]+-c' 2 \
    'the desktop and server commands do not both verify with sha256sum -c'
require_bootstrap_occurrences 'PANAMA_BOOT_REVISION="?\$bootstrap_commit"?[[:space:]]+PANAMA_BOOT_SHA256="?\$bootstrap_sha"?' 2 \
    'the desktop and server commands do not both pass the verified pins to boot'
grep -qE 'bash[[:space:]]+"?\$bootstrap"?([[:space:]]|$)' "$readme" \
    || note 'the README bootstrap does not execute the verified temporary file'
grep -qE 'bash[[:space:]]+"?\$bootstrap"?[[:space:]]+--server' "$readme" \
    || note 'the server bootstrap does not reuse the verified temporary file'
if grep -qE 'curl[^|]*\|[[:space:]]*(bash|sh)|bash[[:space:]]+<\(curl' "$readme"; then
    note 'the README pipes a network response into a shell'
fi

# Run the two exact documented blocks with a successful download and a failing
# checksum. The Bash adapter records only the verified boot invocation; the
# contract itself uses /usr/bin/bash so the adapter cannot hide this behavior.
checksum_stub_dir="$work/checksum-bin"
checksum_boot_calls="$work/checksum-boot-calls"
mkdir -p "$checksum_stub_dir"

cat >"$checksum_stub_dir/curl" <<'STUB'
#!/usr/bin/bash
set -u
destination=""
while (( $# > 0 )); do
    case "$1" in
        --output)
            destination="${2:-}"
            shift 2
            ;;
        *) shift ;;
    esac
done
[[ -n "$destination" ]] || exit 97
printf 'tampered boot bytes\n' >"$destination"
STUB
chmod +x "$checksum_stub_dir/curl"

cat >"$checksum_stub_dir/sha256sum" <<'STUB'
#!/usr/bin/bash
[[ "${1:-}" == -c ]] || exit 97
exit 1
STUB
chmod +x "$checksum_stub_dir/sha256sum"

cat >"$checksum_stub_dir/bash" <<'STUB'
#!/usr/bin/bash
printf 'verified-boot %s\n' "$*" >>"$PANAMA_README_BOOT_CALLS"
exit 0
STUB
chmod +x "$checksum_stub_dir/bash"

mapfile -d $'\036' -t bootstrap_snippets < <(
    awk '
      /^```sh$/ { in_block = 1; block = ""; next }
      /^```$/ && in_block {
        if (block ~ /bootstrap_commit=/) printf "%s%c", block, 30
        in_block = 0
        next
      }
      in_block { block = block $0 "\n" }
    ' "$readme"
)

checksum_failure_stops_boot() {
    local snippet="$1" status
    : >"$checksum_boot_calls"
    PATH="$checksum_stub_dir:/usr/bin:/bin" \
      PANAMA_README_BOOT_CALLS="$checksum_boot_calls" \
      /usr/bin/bash -c "$snippet" >/dev/null 2>&1
    status=$?
    (( status != 0 )) && [[ ! -s "$checksum_boot_calls" ]]
}

if (( ${#bootstrap_snippets[@]} != 2 )); then
    note 'the README does not contain exactly two executable verified bootstrap blocks'
else
    bootstrap_labels=(desktop server)
    for index in "${!bootstrap_snippets[@]}"; do
        snippet="${bootstrap_snippets[$index]}"
        label="${bootstrap_labels[$index]}"
        if ! checksum_failure_stops_boot "$snippet"; then
            note "the $label command invoked boot after checksum failure"
        fi

        weakened_snippet="${snippet//$'set -euo pipefail\n'/}"
        if [[ "$weakened_snippet" == "$snippet" ]]; then
            note "the $label command has no fail-closed shell control to test"
        elif checksum_failure_stops_boot "$weakened_snippet"; then
            note "the $label checksum assertion accepts removal of fail-closed shell control"
        fi
    done
fi

# ── The contract count ───────────────────────────────────────────────────────
#
# Counted the way `panama test` collects the suite, so the README agrees with
# what the runner actually reports rather than with a second idea of it.

actual="$(find "$repo_dir/tests" -type f -not -path '*/fixtures/*' -not -path '*__pycache__*' \
    \( -executable -o -name '*_test.py' \) | wc -l)"

claimed="$(grep -oE '^[0-9]+ of them, under' "$readme" | grep -oE '^[0-9]+')"

if [[ -z "$claimed" ]]; then
    note 'the README no longer states a contract count in the form this checks'
elif (( claimed != actual )); then
    note "the README says $claimed contracts; there are $actual"
fi

# ── Root server bootstrap ───────────────────────────────────────────────────
#
# This path runs before the repository exists on a fresh VPS. Its safety
# properties need to be stated beside the public `boot --server` example, not
# inferred from the shell implementation or buried in a fixture.

bootstrap_doc="$(sed -n '/^That command also works from a brand-new VPS/,/^`install` asks/p' "$readme" | tr '\n' ' ')"

require_bootstrap_doc() {
    local pattern="$1" explanation="$2"
    grep -qiE "$pattern" <<<"$bootstrap_doc" || note "$explanation"
}

assert_bootstrap_probe_rejected() {
    local name="$1" pattern="$2" weakened_doc="$3"
    if grep -qiE "$pattern" <<<"$weakened_doc"; then
        note "the $name assertion accepts its weakened documentation probe"
    fi
}

target_key_requirement='target user owns[^.]*\.ssh[^.]*mode[^.]*([^0-9]|^)0700([^0-9]|$)[^.]*authorized_keys[^.]*mode[^.]*([^0-9]|^)0600([^0-9]|$)'
parseable_key_requirement='(every|each)[^.]*non-?comment[^.]*authorized_keys[^.]*(OpenSSH|ssh-keygen)[^.]*(parse|valid)|(OpenSSH|ssh-keygen)[^-]*parse[^.]*every[^.]*non-?comment'
hardening_continues_requirement='hardening[[:space:]]+is[[:space:]]+unavailable[^.]*without[^.]*verified[^.]*key[^.]*install[[:space:]]+continues[^.]*without[[:space:]]+(it|SSH[[:space:]]+hardening)'
atomic_dropin_requirement='atomic[[:space:]]+same-directory[[:space:]]+drop-in'
rollback_requirement='validation[^.]*reload[^.]*fail[^.]*(restor|rollback)[^.]*previous[[:space:]]+drop-in'
effective_policy_requirement='sshd -T[^.]*root[^.]*target|sshd -T[^.]*target[^.]*root'

require_bootstrap_doc "$target_key_requirement" \
    'the root bootstrap docs do not require target-user ownership with exact 0700/0600 SSH modes'
require_bootstrap_doc "$parseable_key_requirement" \
    'the root bootstrap docs do not require OpenSSH to parse every non-comment key entry'
require_bootstrap_doc "$hardening_continues_requirement" \
    'the root bootstrap docs do not say bootstrap continues without unavailable SSH hardening'
require_bootstrap_doc 'sshd -t' \
    'the root bootstrap docs do not name sshd -t validation'
require_bootstrap_doc "$effective_policy_requirement" \
    'the root bootstrap docs do not name sshd -T checks for root and target contexts'
require_bootstrap_doc "$atomic_dropin_requirement" \
    'the root bootstrap docs do not describe the atomic same-directory drop-in'
require_bootstrap_doc '00-panama\.conf' \
    'the root bootstrap docs do not name the precedence-safe 00-panama.conf drop-in'
require_bootstrap_doc 'PermitRootLogin[^.]*no[^.]*PasswordAuthentication[^.]*no[^.]*KbdInteractiveAuthentication[^.]*no' \
    'the root bootstrap docs do not state all three effective authentication denials'
require_bootstrap_doc 'detected (SSH )?unit.*reload|reload.*detected (SSH )?unit' \
    'the root bootstrap docs do not describe reloading the detected SSH unit'
require_bootstrap_doc "$rollback_requirement" \
    'the root bootstrap docs do not promise rollback on validation or reload failure'
require_bootstrap_doc 'fixture contracts.*(these|this) (path|branch)|fixture contracts.*test' \
    'the root bootstrap docs do not limit proof to fixture contracts'
require_bootstrap_doc 'no real daemon reload.*panama test --safe|panama test --safe.*no real daemon reload' \
    'the root bootstrap docs imply a live daemon reload under the safe suite'

# These prove the semantic assertions above reject the precise omissions they
# guard against. They mutate only the scoped documentation string; README.md
# itself remains the real input that must satisfy the contract.
assert_bootstrap_probe_rejected 'exact SSH modes' "$target_key_requirement" \
    "${bootstrap_doc//0700/700}"
assert_bootstrap_probe_rejected 'target-user ownership' "$target_key_requirement" \
    "${bootstrap_doc//target user owns/someone owns}"
weakened_key_doc="${bootstrap_doc//OpenSSH/text tooling}"
weakened_key_doc="${weakened_key_doc//ssh-keygen/text parser}"
assert_bootstrap_probe_rejected 'OpenSSH key parsing' "$parseable_key_requirement" \
    "$weakened_key_doc"
assert_bootstrap_probe_rejected 'hardening availability' "$hardening_continues_requirement" \
    "${bootstrap_doc//unavailable/available}"
assert_bootstrap_probe_rejected 'hardening continuation' "$hardening_continues_requirement" \
    "${bootstrap_doc//continues/stops}"
assert_bootstrap_probe_rejected 'atomic drop-in' "$atomic_dropin_requirement" \
    "${bootstrap_doc//atomic /}"
assert_bootstrap_probe_rejected 'rollback after failure' "$rollback_requirement" \
    "${bootstrap_doc//restores /keeps }"
assert_bootstrap_probe_rejected 'rollback trigger' "$rollback_requirement" \
    "${bootstrap_doc//fails/works}"
assert_bootstrap_probe_rejected 'effective target policy' "$effective_policy_requirement" \
    "${bootstrap_doc//target/root}"

if grep -qiE 'merely writes? (the )?(SSH )?(drop-in|file)|reload failure.*ignored|ignores? .*reload failure' <<<"$bootstrap_doc"; then
    note 'the root bootstrap docs weaken the transaction by treating the write or reload failure as harmless'
fi

# ── Documented subcommands exist ─────────────────────────────────────────────
#
# A README listing a command the dispatcher does not have sends somebody to a
# 'Unknown command' error, which reads as a broken install rather than a stale
# document.

while read -r subcommand; do
    [[ -n "$subcommand" ]] || continue
    grep -qE "^\s+$subcommand\)" "$panama" \
        || note "the README documents 'panama $subcommand', which the dispatcher does not handle"
done < <(sed -n '/^panama [a-z]/s/^panama \([a-z-]*\).*/\1/p' "$readme" | sort -u)

if (( ${#findings[@]} > 0 )); then
    mapfile -t findings < <(printf '%s\n' "${findings[@]}" | sort -u)
    printf 'readme contract: %d finding(s)\n' "${#findings[@]}" >&2
    printf '  - %s\n' "${findings[@]}" >&2
    exit 1
fi

printf 'readme contract: PASS (%d contracts, as documented)\n' "$actual"