#!/bin/bash
# bleach_zuse_img.sh - Reset disk/zuse.img (or any home-blocks test image)
# back to pristine/unminted state.
#
# disk/zuse.img simulates the physical Zuse superuser thumbdrive for QEMU
# testing (FABRIC-3.md, Phase 8 kickoff). "Bleaching" it means restoring the
# all-zero blank state homeblocks_sig_check() reads as HOMEBLOCKS_SIG_BLANK
# -- i.e. simulating a genuine first boot, so the one-time mint-Zuse flow can
# be exercised repeatedly during development without hand-regenerating the
# whole image each time.
#
# 64MB is only this script's default -- an arbitrary QEMU-test convenience
# size (matching the existing usb-thumbdrive-test.img precedent for BOT
# driver testing scale), not a constraint on real home-blocks thumbdrives.
# The design is not bound to any particular drive size: homeblocks_sig_t's
# own metadata_devblocks field records whatever size is actually observed,
# nothing in the format or this repo hardcodes one. Override with --size-mb
# for a different test size.
#
# Deliberately a flat/raw image, not GPT-partitioned, matching the same
# simplifying assumption homeblocks_sig_check()'s current call site in
# repl.c uses (sig_start_fblock=0) -- both will need to move to a real
# GPT-partition-relative offset together, once a GPT parser exists. Not
# invented ahead of that work here.
#
# Usage: scripts/bleach_zuse_img.sh [path] [--size-mb N]
#   path        Optional override; defaults to disk/zuse.img relative to repo root.
#   --size-mb N Optional override; defaults to 64 (arbitrary test convenience, see above).

set -euo pipefail

REPO_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
IMG="$REPO_ROOT/disk/zuse.img"
SIZE_MB=64

while [ $# -gt 0 ]; do
    case "$1" in
        --size-mb)
            SIZE_MB="$2"
            shift 2
            ;;
        *)
            IMG="$1"
            shift
            ;;
    esac
done

if [ -e "$IMG" ] && [ ! -f "$IMG" ]; then
    echo "bleach_zuse_img: refusing to overwrite non-regular-file '$IMG'" >&2
    exit 1
fi

dd if=/dev/zero of="$IMG" bs=1M count="$SIZE_MB" status=none
echo "bleach_zuse_img: $IMG reset to ${SIZE_MB}MB blank (pristine/unminted)"