#!/usr/bin/env bash
# Test: read I/O fails when network is severed mid-transfer
#
# Creates a 5 MB file on the mock NAS, starts reading it through the FUSE
# mount, then immediately cuts the network.  The background read should fail
# with an I/O error or produce incomplete output because the remote is
# unreachable mid-stream.
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

# --- Arrange ---
start_mock_nas
nas_create_file "bigfile.dat" 51200         # 50 MB — large enough that caching
                                            # takes time, ensuring network cut
                                            # hits mid-transfer

gen_config

start_warpgate
wait_for_mount
wait_for_rc_api

# --- Act ---
# Start a background read of the large file
cat "$TEST_MOUNT/bigfile.dat" > /dev/null 2>&1 &
read_pid=$!
_BG_PIDS+=("$read_pid")

# Brief delay to let the read begin but NOT complete for a 50 MB file
sleep 0.5

# Sever the network link while the read is in progress
inject_network_down

# Wait for the background read to finish (it should error out)
read_ok=0
if wait "$read_pid" 2>/dev/null; then
    read_ok=1
fi

# --- Assert ---
# With a 50 MB file and the network cut after 0.5s, the read must fail.
# The file cannot have been fully cached in that time.
if [[ "$read_ok" -eq 1 ]]; then
    echo "FAIL: background read of 50 MB file succeeded despite network cut" >&2
    echo "  The file should not have been fully cached in 0.5s." >&2
    inject_network_up
    exit 1
fi

# Restore network for clean teardown
inject_network_up

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