#!/usr/bin/env bash
# Rollback optimization changes
set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
source "$SCRIPT_DIR/../../lib/common.sh"

GRUB_FILE="/etc/default/grub"
BACKUP_DIR="$(data_dir backups)"

log_header "Rollback Optimizations"

if [[ $EUID -ne 0 ]]; then
    log_error "This script requires root. Re-run with: sudo make rollback"
    exit 1
fi

# ── 1. GRUB rollback ────────────────────────────────────
log_info "GRUB backups:"
mapfile -t grub_backups < <(find "$BACKUP_DIR" -name 'grub-*.bak' -print 2>/dev/null | sort -r)

if (( ${#grub_backups[@]} == 0 )); then
    log_info "  No GRUB backups found"
else
    for i in "${!grub_backups[@]}"; do
        printf "  [%d] %s\n" "$i" "${grub_backups[$i]}"
    done
    echo ""

    if confirm "Restore most recent GRUB backup?"; then
        # root already checked at script start
        backup="${grub_backups[0]}"
        cp "$backup" "$GRUB_FILE"
        log_success "GRUB restored from: $backup"

        log_info "Regenerating boot configuration..."
        if is_cmd grubby; then
            # On BLS systems, also need to remove args via grubby
            grubby --update-kernel=ALL --remove-args="iommu amdgpu.gttsize ttm.pages_limit" 2>/dev/null || true
            log_success "Boot entries updated via grubby"
        elif [[ -d /boot/grub2 ]]; then
            grub2-mkconfig -o /boot/grub2/grub.cfg
            log_success "GRUB regenerated via grub2-mkconfig"
        elif [[ -d /boot/grub ]]; then
            grub-mkconfig -o /boot/grub/grub.cfg
            log_success "GRUB regenerated via grub-mkconfig"
        else
            log_error "Could not find grubby or grub config directory. Regenerate manually."
        fi
        log_warn "Reboot required for changes to take effect."
    fi
fi

# ── 2. Tuned profile rollback ───────────────────────────
prev_profile_file="$BACKUP_DIR/tuned-previous-profile.txt"
if [[ -f "$prev_profile_file" ]]; then
    prev_profile="$(cat "$prev_profile_file")"
    current="$(tuned-adm active 2>/dev/null | sed 's/Current active profile: //' || echo "unknown")"
    log_info "Tuned profile: $current (previous: $prev_profile)"

    if [[ "$current" != "$prev_profile" ]] && confirm "Restore tuned profile to $prev_profile?"; then
        tuned-adm profile "$prev_profile"
        log_success "Tuned profile restored to: $prev_profile"
    fi
else
    log_info "No previous tuned profile saved"
fi

# ── 3. BIOS reminder ────────────────────────────────────
echo ""
log_warn "BIOS VRAM changes cannot be rolled back automatically."
log_info "To revert: Reboot → F10 → Advanced → UMA Frame Buffer Size → restore previous value"