#!/usr/bin/env bash

# Application permissions, as far as the desktop can actually enforce them.
#
# The rules:
#
#   1. The page never claims more than the portal can do. A native binary opens
#      /dev/video0 directly, and a settings page implying otherwise is worse
#      than one that says nothing -- so the limit is stated on the page, not
#      buried in a comment.
#   2. A table nothing has asked for is reported empty, not omitted. "No
#      application uses your microphone" and a page that quietly leaves the
#      microphone out look identical and mean very different things.
#   3. Absence is not failure. The store answers "No entry for microphone" for a
#      table nobody has requested; treating that as an error would make the
#      whole page fail because one device is unused.
#   4. Anything that is not an explicit "yes" is withheld. Guessing generously
#      about a camera is the wrong way to be wrong.
#   5. A refusal states its reason.
#   6. THE NEW ONE. screencast and remote-desktop do not hold yes/no. Their
#      permissions are structured GVariants -- which monitors, whether the
#      pointer is included, how long the grant lasts -- and there is no honest
#      way to reconstruct one from a switch. So those two tables are
#      revoke-only: DeletePermission exists for them and SetPermission does not,
#      anywhere, because a toggle that writes a plausible-looking variant would
#      silently rewrite a grant the user never described.
#
# SAFETY: this file makes NO live portal writes. The earlier version set and
# cleared a camera permission on the real permission store under a probe
# application id and put it back afterwards; the write path is now exercised
# against a recording `busctl` stub under `env -i`, with the session bus
# address pointed at a socket that does not exist. Nothing here can reach the
# store this desktop is actually using.

set -uo pipefail

repo_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
helper="$repo_dir/config/dot/quickshell/scripts/panama-permissions"
service="$repo_dir/config/dot/quickshell/services/Permissions.qml"
page="$repo_dir/config/dot/quickshell/modules/settings/PrivacyPage.qml"
qml_dir="$repo_dir/config/dot/quickshell"

fail() {
    printf 'permissions contract: %s\n' "$1" >&2
    exit 1
}

for path in "$helper" "$service" "$page"; do
    [[ -r "$path" ]] || fail "missing $path"
done
[[ -x "$helper" ]] || fail 'panama-permissions is not executable'
command -v jq >/dev/null 2>&1 || { printf 'permissions contract: SKIP (no jq)\n'; exit 0; }

work="$(mktemp -d /tmp/panama-permissions.XXXXXX)"
trap 'rm -rf "$work"' EXIT

# ── 1. The page states the limit ────────────────────────────────────────────

grep -q 'directly' "$page" \
    || fail 'the page does not say that programs outside the portal reach these devices anyway'

# ── 6a. No Set path for the structured tables, by AST ────────────────────────
#
# Read from the syntax tree rather than by grepping for the word, because the
# thing being pinned is reachability: which table names can arrive at the one
# call that writes. A second settable list, or a settable list that quietly
# grew "screencast", is exactly the change this has to catch.

python3 - "$helper" <<'PY' || fail 'the helper can write a permission for a table whose values it cannot construct'
import ast
import importlib.machinery
import importlib.util
import sys

path = sys.argv[1]
source = open(path, encoding="utf-8").read()
tree = ast.parse(source)

# Imported rather than pattern-matched, so the lists are read at their real
# values. They are derived from a table registry rather than typed out, and a
# contract that only understood one spelling of that would be pinning the
# spelling. Importing is safe: the module does its work under __main__.
loader = importlib.machinery.SourceFileLoader("panama_permissions", path)
module = importlib.util.module_from_spec(importlib.util.spec_from_loader(loader.name, loader))
# Registered before it runs: a dataclass declared inside it looks its own module
# up by name while the decorator is running.
sys.modules[loader.name] = module
loader.exec_module(module)

structured = {"screencast", "remote-desktop"}


def as_names(value):
    if isinstance(value, dict):
        value = list(value)
    if isinstance(value, (list, tuple, set, frozenset)):
        names = [item for item in value if isinstance(item, str)]
        return set(names) if len(names) == len(list(value)) else set()
    return set()


collections = {name: as_names(getattr(module, name))
               for name in dir(module) if not name.startswith("_")}
collections = {name: value for name, value in collections.items() if value}

known = {name for name, value in collections.items() if structured <= value}
if not known:
    raise SystemExit("nothing in the helper names screencast and remote-desktop as tables, "
                     "so it does not know they exist")

# Exactly one place writes. More than one is two policies, and the second one
# is the one that falls behind.
writers = []
deleters = []
for node in ast.walk(tree):
    if isinstance(node, ast.FunctionDef):
        literals = [inner.value for inner in ast.walk(node)
                    if isinstance(inner, ast.Constant) and isinstance(inner.value, str)]
        if "SetPermission" in literals:
            writers.append(node)
        if "DeletePermission" in literals:
            deleters.append(node)

if len(writers) != 1:
    raise SystemExit(f"expected exactly one function calling SetPermission, found "
                     f"{[node.name for node in writers]}")
if not deleters:
    raise SystemExit("nothing calls DeletePermission, so a grant can never be revoked")

# One call site, not merely one function. A second Set inside the same function,
# reached by a different branch, would satisfy the count above and defeat the
# membership check below it.
call_sites = sum(1 for node in ast.walk(tree)
                 if isinstance(node, ast.Constant) and node.value == "SetPermission")
if call_sites != 1:
    raise SystemExit(f"SetPermission is named {call_sites} times; there is one honest "
                     "place to write a permission and it is not two")

writer = writers[0]
writer_names = {inner.id for inner in ast.walk(writer) if isinstance(inner, ast.Name)}

# The gate: a named list of table names, consulted by the one function that
# writes. A chain of conditions would do the same job today and grow an
# exception later; a list membership is one place to look.
gate = {name for name in writer_names & set(collections) if "camera" in collections[name]}
if not gate:
    raise SystemExit(f"{writer.name} writes without consulting any list of the tables that "
                     "MAY be written, so refusing screencast is a runtime accident rather "
                     "than a rule")

# The way this breaks is not by deleting the list; it is by somebody adding
# "screencast" to it because the page wanted a switch there.
for name in gate:
    if structured & collections[name]:
        raise SystemExit(f"{name}, which {writer.name} consults before writing, lists "
                         f"{sorted(structured & collections[name])} alongside the tables "
                         "that carry a plain yes/no")

writer_literals = {inner.value for inner in ast.walk(writer)
                   if isinstance(inner, ast.Constant) and isinstance(inner.value, str)}
leaked = structured & writer_literals
if leaked:
    raise SystemExit(f"{writer.name} mentions {sorted(leaked)} by name, next to the one call "
                     "that writes a permission")
PY

# ── 6b. Nothing in the shell asks to set a structured table ─────────────────
#
# The rule said from the QML side: no page and no service may hand a
# revoke-only table to the write path, whatever the helper would do with it.
offenders="$(grep -rn --include='*.qml' -E 'setPermission\([^)]*(screencast|remote-desktop)' "$qml_dir" || true)"
[[ -z "$offenders" ]] \
    || fail "something offers to set a permission it cannot construct: $offenders"

grep -q 'revoke' "$service" \
    || fail 'the Permissions service has no revoke path, so a structured grant is permanent'
grep -qE 'revokeOnlyTables|revokeOnly' "$service" \
    || fail 'the service does not name which tables are revoke-only, so the page has to guess'
grep -qE 'simpleTables|simpleValued' "$service" \
    || fail 'the service does not name which tables carry a plain yes/no'
grep -q 'tables' "$service" \
    || fail 'the service does not expose the per-table model the page is built from'

# The Applications page reads the camera/microphone half of this service in the
# older `devices` shape. Generalizing the model to six tables kept that view
# rather than rewriting a second page's bindings, and something has to notice if
# it disappears -- the symptom there is an empty list, not an error.
grep -q 'property var devices' "$service" \
    || fail 'the devices view is gone; ApplicationsPage reads it and would quietly show nothing'
consumers="$(grep -rln --include='*.qml' 'Permissions\.devices' "$qml_dir" || true)"
[[ -n "$consumers" ]] \
    || fail 'nothing reads Permissions.devices any more, so the compatibility view is dead weight'

# ── The hermetic bus ────────────────────────────────────────────────────────
#
# A recording `busctl` first on PATH, answering from a fixture. The proof that
# it is the one being called is the fixture's own application ids coming back
# out of `snapshot` -- asserted before anything that writes runs.

mkdir -p "$work/bin"
export PANAMA_PERMISSIONS_CALL_LOG="$work/calls"
: >"$PANAMA_PERMISSIONS_CALL_LOG"

cat >"$work/bin/busctl" <<'STUB'
#!/usr/bin/env bash
# A permission store that exists only inside this contract.
#
# The method and its arguments are read positionally rather than by pattern, so
# `List s screencast` and `Lookup ss screencast <token>` answer with the shapes
# the real store answers with -- an array of ids for one, a dictionary of
# applications for the other. Answering both with the same shape would let a
# helper that never lists a table pass anyway.
printf '%s\n' "$*" >>"$PANAMA_PERMISSIONS_CALL_LOG"

method=""
rest=()
collecting=0
for argument in "$@"; do
    if (( collecting )); then
        rest+=("$argument")
        continue
    fi
    case "$argument" in
        List|Lookup|SetPermission|DeletePermission|GetPermission)
            method="$argument"
            collecting=1 ;;
    esac
done

if [[ -z "$method" ]]; then
    # `busctl --user list`, which is how the helper asks whether the store is
    # running at all.
    printf 'org.freedesktop.impl.portal.PermissionStore 1234 - - - -\n'
    exit 0
fi

table="${rest[1]:-}"
entry="${rest[2]:-}"

ids() { printf '{"type":"as","data":[[%s]]}\n' "$1"; }
row() { printf '{"type":"a{sas}v","data":[%s,{"type":"s","data":""}]}\n' "$1"; }
absent() { printf 'No entry for %s\n' "$1" >&2; exit 1; }

case "$method" in
    SetPermission|DeletePermission)
        printf '{"type":"","data":[]}\n'
        exit 0 ;;
    List)
        case "$table" in
            # Two remembered sessions for one application, which is the normal
            # case: the page asks one question and the store holds four answers.
            # The third id is deliberately not an id -- a store that handed back
            # something path-shaped must not have it fed straight back in.
            screencast)      ids '"session-a","session-b","../../etc/passwd"' ;;
            remote-desktop)  ids '"session-r"' ;;
            background)      ids '"background"' ;;
            location)        ids '' ;;
            *)               ids '' ;;
        esac
        exit 0 ;;
    Lookup)
        case "$table/$entry" in
            devices/camera)
                row '{"org.panama.FixtureCam":["yes"],"org.panama.FixtureBlocked":["no"]}' ;;
            devices/microphone)
                # Nothing has ever asked. The store says so by having no row.
                absent microphone ;;
            screencast/session-a|screencast/session-b)
                row '{"org.panama.FixtureCast":["1","screen","0"]}' ;;
            remote-desktop/session-r)
                row '{"org.panama.FixtureRemote":["1","keyboard,pointer","0"]}' ;;
            background/background)
                row '{"org.panama.FixtureBackground":["yes"],"org.panama.FixtureQuiet":["no"]}' ;;
            *)
                absent "${entry:-$table}" ;;
        esac
        exit 0 ;;
esac
printf '{"type":"","data":[]}\n'
STUB
chmod +x "$work/bin/busctl"

runh() {
    env -i \
        PATH="$work/bin:/usr/bin:/bin" \
        HOME="$work/home" \
        XDG_RUNTIME_DIR="$work/run" \
        DBUS_SESSION_BUS_ADDRESS="unix:path=$work/no-such-bus" \
        PANAMA_PERMISSIONS_CALL_LOG="$PANAMA_PERMISSIONS_CALL_LOG" \
        LANG=C LC_ALL=C \
        "$helper" "$@"
}
mkdir -p "$work/home" "$work/run"

# The helper has to find busctl on PATH for the stub to mean anything.
grep -qE '/usr/bin/busctl|/bin/busctl' "$helper" \
    && fail 'the helper names an absolute busctl, so it cannot be pointed at a fixture'

resolved="$(env -i PATH="$work/bin:/usr/bin:/bin" command -v busctl)"
[[ "$resolved" == "$work/bin/busctl" ]] \
    || fail "busctl resolves to $resolved, not the stub; refusing to run anything that writes"

calls() { cat "$PANAMA_PERMISSIONS_CALL_LOG"; }
wrote() { grep -c 'SetPermission' "$PANAMA_PERMISSIONS_CALL_LOG"; }
deleted() { grep -c 'DeletePermission' "$PANAMA_PERMISSIONS_CALL_LOG"; }

state="$(runh snapshot)" || fail 'snapshot failed against the fixture bus'

# ── 2, 3 & 4. The shape, and the fixture proving this ran against the stub ──

jq -e '.available == true and (.tables | type == "object") and .error == ""' <<<"$state" >/dev/null \
    || fail "snapshot is not the tables shape the page is built from: $state"

for table in camera microphone screencast remote-desktop background; do
    jq -e --arg t "$table" '.tables | has($t)' <<<"$state" >/dev/null \
        || fail "the $table table is missing from the snapshot entirely"
    jq -e --arg t "$table" '[.tables[$t][] | has("app") and has("allowed")] | all' <<<"$state" >/dev/null \
        || fail "a $table row is not { app, allowed }"
    # `grants` is how a folded row says how many stored answers are behind it,
    # and `raw` is the store's own value -- the page explains a structured grant
    # rather than reducing it to a switch, and cannot do that from a boolean.
    jq -e --arg t "$table" '[.tables[$t][] | has("grants") and has("raw")] | all' <<<"$state" >/dev/null \
        || fail "a $table row carries no grant count, so a folded row cannot say what it folded"
done

# The tables the model dropped. "speakers" was in the devices list because the
# portal has an entry for it, not because anything ever asks: no portal backend
# arbitrates speaker access, so the row was a permanent "nothing has asked" for
# a question nobody is asking. Listing it made the page look like it covered
# more than it does.
jq -e '.tables | has("speakers") | not' <<<"$state" >/dev/null \
    || fail 'speakers is back in the permissions model, where nothing ever asks'

# The proof of the fixture: these ids exist nowhere but in this file.
jq -e '[.tables.camera[] | select(.app == "org.panama.FixtureCam" and .allowed == true)] | length == 1' \
    <<<"$state" >/dev/null \
    || fail "snapshot did not read the fixture's camera table; refusing to go on: $state"
jq -e '[.tables.camera[] | select(.app == "org.panama.FixtureBlocked" and .allowed == false)] | length == 1' \
    <<<"$state" >/dev/null \
    || fail 'a permission that is not an explicit yes was reported as allowed'

# Rule 3, from the store's own words: "No entry for microphone" is a table
# nobody has asked about, not a failure of the page.
jq -e '.tables.microphone == []' <<<"$state" >/dev/null \
    || fail "an unused table was not reported as empty: $(jq -c .tables.microphone <<<"$state")"
jq -e '.error == ""' <<<"$state" >/dev/null \
    || fail 'an unused table was reported as an error, which fails the whole page over one unused device'

jq -e '[.tables["remote-desktop"][] | select(.app == "org.panama.FixtureRemote")] | length == 1' \
    <<<"$state" >/dev/null \
    || fail 'a structured grant was dropped rather than listed for revoking'

# One application, two remembered screencast sessions, ONE row. The page asks
# "may this application share your screen", which is one question; a store that
# holds four answers to it must not become four rows.
jq -e '[.tables.screencast[] | select(.app == "org.panama.FixtureCast")] | length == 1' \
    <<<"$state" >/dev/null \
    || fail "one application's several remembered sessions became several rows: $(jq -c .tables.screencast <<<"$state")"

# An id the store handed back that is not an id shape is dropped, not fed
# straight back into a Lookup.
grep -qF '../../etc/passwd' "$PANAMA_PERMISSIONS_CALL_LOG" \
    && fail 'a path-shaped entry id from the store was passed back into the permission store'

# The two lists the page builds itself from, and they do not overlap.
jq -e '(.simpleTables | index("screencast")) == null
    and (.simpleTables | index("remote-desktop")) == null
    and (.revokeOnlyTables | index("screencast")) != null
    and (.revokeOnlyTables | index("remote-desktop")) != null' <<<"$state" >/dev/null \
    || fail "the page is told the wrong tables are toggleable: $(jq -c '{simpleTables,revokeOnlyTables}' <<<"$state")"

# ── 6c. The write path, at runtime ──────────────────────────────────────────
#
# Which vocabulary the helper takes is read from the helper rather than
# assumed, so this pins the rule and not the spelling.

probe="org.panama.ContractProbe"
verb=""
for candidate in true allow; do
    : >"$PANAMA_PERMISSIONS_CALL_LOG"
    if [[ "$(runh set camera "$probe" "$candidate" | jq -r '.error')" == "" ]]; then
        verb="$candidate"
        break
    fi
done
[[ -n "$verb" ]] || fail 'the helper accepted neither `set camera APP true` nor `set camera APP allow`'
(( "$(wrote)" >= 1 )) \
    || fail "setting a simple table never reached SetPermission: $(calls)"

# Background is the other toggleable one, and the one people actually come to
# this page for.
: >"$PANAMA_PERMISSIONS_CALL_LOG"
reason="$(runh set background "$probe" "$verb" | jq -r '.error')"
[[ -z "$reason" ]] || fail "the background table refused a plain yes/no write: $reason"
(( "$(wrote)" >= 1 )) || fail "setting background never reached SetPermission: $(calls)"

# The applications the fixture store actually holds a grant for -- forgetting
# something nobody granted is a different case, checked below.
declare -A GRANT_HOLDER=(
    [screencast]=org.panama.FixtureCast
    ["remote-desktop"]=org.panama.FixtureRemote
)

for table in screencast remote-desktop; do
    holder="${GRANT_HOLDER[$table]}"

    : >"$PANAMA_PERMISSIONS_CALL_LOG"
    reason="$(runh set "$table" "$holder" "$verb" | jq -r '.error')"
    [[ -n "$reason" ]] \
        || fail "setting $table was accepted, but its value cannot be honestly constructed"
    (( "$(wrote)" == 0 )) \
        || fail "setting $table was refused in words but still wrote to the store: $(calls)"

    # Revoking, which is the one thing these tables do support.
    : >"$PANAMA_PERMISSIONS_CALL_LOG"
    reason="$(runh forget "$table" "$holder" | jq -r '.error')"
    [[ -z "$reason" ]] || fail "revoking a $table grant was refused: $reason"
    (( "$(deleted)" >= 1 )) \
        || fail "revoking $table never reached DeletePermission: $(calls)"
done

# Every remembered session, not the first one. An application with two stored
# screencast grants whose row still says "allowed" after Revoke is the failure
# this catches.
: >"$PANAMA_PERMISSIONS_CALL_LOG"
runh forget screencast org.panama.FixtureCast >/dev/null
(( "$(deleted)" == 2 )) \
    || fail "revoking dropped $(deleted) of the fixture's two remembered screencast sessions"

# Forgetting something nobody granted says so rather than reporting success.
: >"$PANAMA_PERMISSIONS_CALL_LOG"
reason="$(runh forget screencast "$probe" | jq -r '.error')"
[[ -n "$reason" ]] || fail 'revoking a grant that does not exist reported success'
(( "$(deleted)" == 0 )) || fail 'revoking a grant that does not exist still deleted something'

# ── 5. Refusals name their reason, and reach nothing ────────────────────────

: >"$PANAMA_PERMISSIONS_CALL_LOG"
reason="$(runh set camera "$probe" maybe | jq -r '.error')"
[[ -n "$reason" ]] || fail 'an invalid decision was accepted'
(( "$(wrote)" == 0 )) || fail 'an invalid decision still wrote to the store'

for bad_table in nonsense ../devices 'devices camera' ''; do
    : >"$PANAMA_PERMISSIONS_CALL_LOG"
    reason="$(runh set "$bad_table" "$probe" "$verb" | jq -r '.error')"
    [[ -n "$reason" ]] || fail "the table id '$bad_table' was accepted"
    (( "$(wrote)" == 0 )) || fail "the table id '$bad_table' reached the store"
    reason="$(runh forget "$bad_table" "$probe" | jq -r '.error')"
    [[ -n "$reason" ]] || fail "forgetting the table id '$bad_table' was accepted"
done

for bad_app in '../../etc/passwd' 'not an app' '' '-'; do
    : >"$PANAMA_PERMISSIONS_CALL_LOG"
    reason="$(runh set camera "$bad_app" "$verb" | jq -r '.error')"
    [[ -n "$reason" ]] || fail "the application id '$bad_app' was accepted"
    (( "$(wrote)" == 0 )) || fail "the application id '$bad_app' reached the store"
done

# A refusal answers in the page's own shape rather than collapsing: the page
# reads .tables off every reply, including the ones that say no.
jq -e '.tables | type == "object"' <<<"$(runh set nonsense "$probe" "$verb")" >/dev/null \
    || fail 'a refusal came back without the tables the page is bound to'

printf 'permissions contract: PASS (tables read from a fixture bus, no live portal write)\n'