#!/usr/bin/env bash
# Test: behavior when a cached file is corrupted on disk
#
# Verifies what happens when a file in the VFS cache is corrupted between
# warpgate restarts.  rclone may serve the corrupted data from cache or
# re-fetch from the remote — this test documents the observed behavior.
#
# Sequence:
#   1. Create a test file on the NAS with known content.
#   2. Start warpgate, read file through mount to cache it.
#   3. Stop warpgate gracefully.
#   4. Overwrite the cached file with garbage data.
#   5. Restart warpgate with a short dir_cache_time (1s).
#   6. Wait for dir cache to expire, then read through mount.
#   7. Compare result against expected content and document behavior.
set -euo pipefail
SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
source "$SCRIPT_DIR/../harness/helpers.sh"
source "$SCRIPT_DIR/../harness/mock-nas.sh"

require_root
setup_test_env
trap teardown_test_env EXIT

# Start the mock NAS and create a test file
start_mock_nas
nas_create_file_content "corrupt-test.txt" "original"

# Generate config with short dir_cache_time so rclone rechecks the remote
gen_config dir_cache_time=1s

# Start warpgate and wait for readiness
start_warpgate
wait_for_mount
wait_for_rc_api

# Read file through the FUSE mount to pull it into cache
content_before=$(cat "$TEST_MOUNT/corrupt-test.txt")
if [[ "$content_before" != "original" ]]; then
    echo "FAIL: initial read returned unexpected content: $content_before" >&2
    exit 1
fi
assert_cached "corrupt-test.txt"
echo "INFO: file cached successfully, content: '$content_before'"

# Stop warpgate gracefully
stop_warpgate

# Corrupt the cached file by overwriting with garbage
cache_file="$CACHE_DIR/vfs/nas/corrupt-test.txt"
if [[ ! -f "$cache_file" ]]; then
    echo "FAIL: cache file not found at $cache_file" >&2
    exit 1
fi
echo -n "CORRUPTED-GARBAGE-DATA" > "$cache_file"
echo "INFO: corrupted cache file at $cache_file"

# Restart warpgate
start_warpgate
wait_for_mount 60
wait_for_rc_api

# Wait for the dir cache to expire (1s dir_cache_time + margin)
sleep 3

# Read the file through the mount again
content_after=$(cat "$TEST_MOUNT/corrupt-test.txt")

echo "INFO: content after restart with corrupted cache: '$content_after'"

# The corrupted cache file has a different size than the NAS original
# ("CORRUPTED-GARBAGE-DATA" = 22 bytes vs "original" = 8 bytes).
# rclone VFS should detect the size mismatch and re-fetch from the remote.
# We MUST verify the file matches the NAS original — serving corrupted data
# is a data integrity failure.
nas_original=$(nas_read_file "corrupt-test.txt")
if [[ "$content_after" != "$nas_original" ]]; then
    echo "FAIL: content after restart does not match NAS original" >&2
    echo "  NAS original:  '$nas_original'" >&2
    echo "  mount returned: '$content_after'" >&2
    exit 1
fi

echo "INFO: rclone correctly re-fetched file from remote (corruption detected)"

echo "PASS: $(basename "$0" .sh)"