#!/bin/bash
# extract-core.sh — Extract Tiny Core Linux rootfs from ISO
set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
CACHE_DIR="${CACHE_DIR:-$PROJECT_ROOT/build/cache}"
ROOTFS_DIR="${ROOTFS_DIR:-$PROJECT_ROOT/build/rootfs-work}"

# shellcheck source=../config/versions.env
. "$SCRIPT_DIR/../config/versions.env"

TC_ISO="$CACHE_DIR/$TINYCORE_ISO"
ISO_MNT="$ROOTFS_DIR/iso-mount"

if [ ! -f "$TC_ISO" ]; then
    echo "ERROR: Tiny Core ISO not found: $TC_ISO"
    echo "Run 'make fetch' first."
    exit 1
fi

# Clean previous rootfs
rm -rf "$ROOTFS_DIR"
mkdir -p "$ROOTFS_DIR" "$ISO_MNT"

# --- Mount ISO and extract kernel + initramfs ---
echo "==> Mounting ISO: $TC_ISO"
mount -o loop,ro "$TC_ISO" "$ISO_MNT" 2>/dev/null || {
    # Fallback for non-root: use 7z or bsdtar
    echo "    mount failed (need root?), trying bsdtar..."
    mkdir -p "$ISO_MNT"
    bsdtar xf "$TC_ISO" -C "$ISO_MNT" 2>/dev/null || {
        echo "    bsdtar failed, trying 7z..."
        7z x -o"$ISO_MNT" "$TC_ISO" >/dev/null 2>&1
    }
}

# Find vmlinuz and core.gz (path varies by Tiny Core version/arch)
VMLINUZ=""
COREGZ=""
for f in "$ISO_MNT"/boot/vmlinuz64 "$ISO_MNT"/boot/vmlinuz; do
    [ -f "$f" ] && VMLINUZ="$f" && break
done
for f in "$ISO_MNT"/boot/corepure64.gz "$ISO_MNT"/boot/core.gz; do
    [ -f "$f" ] && COREGZ="$f" && break
done

if [ -z "$VMLINUZ" ] || [ -z "$COREGZ" ]; then
    echo "ERROR: Could not find vmlinuz/core.gz in ISO"
    echo "ISO contents:"
    find "$ISO_MNT" -type f
    umount "$ISO_MNT" 2>/dev/null || true
    exit 1
fi

echo "==> Found kernel: $VMLINUZ"
echo "==> Found initramfs: $COREGZ"

# Copy kernel
cp "$VMLINUZ" "$ROOTFS_DIR/vmlinuz"

# --- Extract initramfs (core.gz → rootfs) ---
echo "==> Extracting initramfs..."
mkdir -p "$ROOTFS_DIR/rootfs"
cd "$ROOTFS_DIR/rootfs"
zcat "$COREGZ" | cpio -idm 2>/dev/null

# Unmount ISO
cd "$PROJECT_ROOT"
umount "$ISO_MNT" 2>/dev/null || true
rm -rf "$ISO_MNT"

echo "==> Rootfs extracted: $ROOTFS_DIR/rootfs"
echo "    Size: $(du -sh "$ROOTFS_DIR/rootfs" | cut -f1)"
echo "    Kernel: $ROOTFS_DIR/vmlinuz ($(du -h "$ROOTFS_DIR/vmlinuz" | cut -f1))"

# --- Audit kernel config if available ---
if [ -f "$ROOTFS_DIR/rootfs/proc/config.gz" ]; then
    echo "==> Kernel config found in rootfs, auditing..."
    "$SCRIPT_DIR/../config/kernel-audit.sh" <(zcat "$ROOTFS_DIR/rootfs/proc/config.gz") || true
fi

echo "==> Extract complete."