#!/bin/bash

# Enable strict error handling
set -e

# Function to log messages with timestamps
log() {
    echo "$(date '+%F %T') - $@"
}

# Function to display usage information
usage() {
    echo "Usage: $0 [-d DEVICE] [-f FARM] [-e ENVIRONMENT]"
    echo "  -d, --device DEVICE      Specify the block device to use (e.g., sda, nvme0n1)."
    echo "  -f, --farm FARM          Specify the FARM ID."
    echo "  -e, --environment ENV    Specify the environment (dev, qa, test, prod)."
    echo "  -h, --help               Display this help message."
    exit 1
}

# Function to find a suitable block device
find_blockdev() {
    # Minimum size in bytes, e.g., 10 GiB
    MIN_SIZE=$((10 * 1024 * 1024 * 1024))

    # Search for NVMe devices first
    log "Searching for NVMe devices..."
    for DEV in /dev/nvme*n1; do
        if [ -b "$DEV" ]; then
            SIZE_BYTES=$(blockdev --getsize64 "$DEV")
            if [ "$SIZE_BYTES" -ge "$MIN_SIZE" ]; then
                log "Found NVMe device: $DEV ($(numfmt --to=iec $SIZE_BYTES))"
                BLOCKDEV="${DEV##*/}"
                return 0
            else
                log "$DEV is smaller than $(numfmt --to=iec $MIN_SIZE). Skipping."
            fi
        fi
    done

    # If no NVMe device found, search for SSD devices
    log "No suitable NVMe device found. Searching for SSD devices..."
    for DEV_PATH in /sys/block/*; do
        DEV_NAME=$(basename "$DEV_PATH")
        # Exclude unwanted devices
        case "$DEV_NAME" in
            loop*|ram*|sr*|fd*|md*|dm-*)
                continue
                ;;
        esac
        DEVICE="/dev/$DEV_NAME"
        if [ -b "$DEVICE" ] && [ -e "/sys/block/$DEV_NAME/queue/rotational" ] && [ "$(cat /sys/block/$DEV_NAME/queue/rotational)" == "0" ]; then
            SIZE_BYTES=$(blockdev --getsize64 "$DEVICE")
            if [ "$SIZE_BYTES" -ge "$MIN_SIZE" ]; then
                log "Found SSD device: $DEVICE ($(numfmt --to=iec $SIZE_BYTES))"
                BLOCKDEV="$DEV_NAME"
                return 0
            else
                log "$DEVICE is smaller than $(numfmt --to=iec $MIN_SIZE). Skipping."
            fi
        fi
    done

    log "No suitable block device found."
    return 1
}

# Function to manage UEFI boot entries
manage_boot_entries() {
    log "Managing UEFI boot entries..."

    # Check if efibootmgr is available
    if ! command -v efibootmgr &> /dev/null; then
        log "Error: 'efibootmgr' is not installed. Please install it and rerun the script."
        exit 1
    fi

    # Get the list of current boot entries
    CURRENT_BOOT_ENTRIES=$(efibootmgr | grep "BootOrder")
    log "Current BootOrder: $CURRENT_BOOT_ENTRIES"

    # Delete all existing boot entries except the EFI Shell (if present)
    log "Deleting existing boot entries..."
    BOOT_ENTRIES=$(efibootmgr | grep -E "^Boot[0-9A-F]{4}" | awk '{print $1}' | sed 's/\*//')
    for ENTRY in $BOOT_ENTRIES; do
        efibootmgr -b ${ENTRY#Boot} -B
        log "Deleted boot entry $ENTRY"
    done

    # Create a new boot entry pointing to BOOTX64.EFI on the first partition
    log "Creating new boot entry for /dev/${PARTPREFIX}1..."
    # Adjust the partition number if necessary
    ESP_PART_NUM=1
    efibootmgr -c -d /dev/${BLOCKDEV} -p $ESP_PART_NUM -L "Zero-OS" -l "\\EFI\\BOOT\\BOOTX64.EFI" || {
        log "Error: Failed to create new boot entry."
        exit 1
    }

    # Set the boot order to include only the new boot entry
    NEW_BOOT_NUM=$(efibootmgr | grep "Zero-OS" | awk '{print $1}' | sed 's/\*//;s/Boot//')
    if [ -z "$NEW_BOOT_NUM" ]; then
        log "Error: Failed to retrieve new boot entry number."
        exit 1
    fi
    log "Setting BootOrder to only include Boot$NEW_BOOT_NUM..."
    efibootmgr -o $NEW_BOOT_NUM || {
        log "Error: Failed to set new BootOrder."
        exit 1
    }

    log "New BootOrder set successfully."
}

# Main script execution
main() {
    # Default values
    BLOCKDEV_SPECIFIED=""
    FARM="1234"
    ENVIRONMENT="prod"

    # Parse command-line arguments
    while [[ $# -gt 0 ]]; do
        case "$1" in
            -d|--device)
                shift
                if [ -z "$1" ]; then
                    log "Error: '--device' requires a non-empty option argument."
                    usage
                fi
                BLOCKDEV_SPECIFIED="$1"
                shift
                ;;
            -f|--farm)
                shift
                if [ -z "$1" ]; then
                    log "Error: '--farm' requires a non-empty option argument."
                    usage
                fi
                FARM="$1"
                shift
                ;;
            -e|--environment)
                shift
                if [ -z "$1" ]; then
                    log "Error: '--environment' requires a non-empty option argument."
                    usage
                fi
                ENVIRONMENT="$1"
                shift
                ;;
            -h|--help)
                usage
                ;;
            *)
                log "Error: Unknown option: $1"
                usage
                ;;
        esac
    done

    # Validate environment
    case "$ENVIRONMENT" in
        dev|qa|test|prod)
            log "Using environment: $ENVIRONMENT"
            ;;
        *)
            log "Error: Invalid environment '$ENVIRONMENT'. Valid options are 'dev', 'qa', 'test', 'prod'."
            exit 1
            ;;
    esac

    if [ -n "$BLOCKDEV_SPECIFIED" ]; then
        # Use the specified block device
        if [[ "$BLOCKDEV_SPECIFIED" != /dev/* ]]; then
            BLOCKDEV_SPECIFIED="/dev/$BLOCKDEV_SPECIFIED"
        fi
        if [ ! -b "$BLOCKDEV_SPECIFIED" ]; then
            log "Error: Specified device $BLOCKDEV_SPECIFIED does not exist or is not a block device."
            exit 1
        fi
        BLOCKDEV="${BLOCKDEV_SPECIFIED##*/}"
        log "Using specified block device: $BLOCKDEV_SPECIFIED"
    else
        # Find a suitable block device
        if ! find_blockdev; then
            log "Error: No suitable block device found."
            exit 1
        fi
        log "Selected block device: /dev/${BLOCKDEV}"
    fi

    # Confirm with the user before proceeding
    read -p "This will erase all data on /dev/${BLOCKDEV}. Are you sure you want to proceed? (yes/[no]): " CONFIRM
    if [ "$CONFIRM" != "yes" ]; then
        log "Operation cancelled by user."
        exit 0
    fi

    # Determine partition naming convention
    if [[ $BLOCKDEV =~ [0-9]$ ]]; then
        PARTPREFIX="${BLOCKDEV}p"
    else
        PARTPREFIX="${BLOCKDEV}"
    fi

    # Wipe filesystem signatures
    log "Wiping filesystem signatures on /dev/${BLOCKDEV}..."
    wipefs -a -f /dev/${BLOCKDEV} || { log "Failed to wipe filesystem signatures."; exit 1; }

    # Create GPT partition table
    log "Creating GPT partition table on /dev/${BLOCKDEV}..."
    parted -s /dev/${BLOCKDEV} mklabel gpt || { log "Failed to create GPT partition table."; exit 1; }

    # Create partitions
    log "Creating partitions on /dev/${BLOCKDEV}..."
    if ! parted -s /dev/${BLOCKDEV} "mkpart zosboot fat32 1MiB 300MiB set 1 esp on mkpart zoscache btrfs 300MiB 100%"; then
        log "Failed to create partitions."
        exit 1
    fi

    # Format partitions
    log "Formatting /dev/${PARTPREFIX}1 as FAT32..."
    if ! mkfs.vfat -F32 /dev/${PARTPREFIX}1; then
        log "Failed to format /dev/${PARTPREFIX}1 as FAT32."
        exit 1
    fi

    log "Formatting /dev/${PARTPREFIX}2 as BTRFS..."
    if ! mkfs.btrfs -f /dev/${PARTPREFIX}2; then
        log "Failed to format /dev/${PARTPREFIX}2 as BTRFS."
        exit 1
    fi

    # Mount and prepare directories
    MOUNT_POINT="zospxe"
    log "Creating and mounting directory ./${MOUNT_POINT}..."
    mkdir -p "${MOUNT_POINT}"
    if ! mount /dev/${PARTPREFIX}1 -t vfat "${MOUNT_POINT}"; then
        log "Failed to mount /dev/${PARTPREFIX}1 to ${MOUNT_POINT}."
        exit 1
    fi

    log "Creating directory structure in ${MOUNT_POINT}..."
    mkdir -p "${MOUNT_POINT}/efi/boot"

    # Download the required BOOTX64.EFI file
    # NOTE:: EDIT THIS WHEN APPROPRIATE AND IN PROD
    EFI_FILE_URL="https://bootstrap.grid.tf/uefi/${ENVIRONMENT}/${FARM}/debug/zero-os-development-zos-v4-debug-7d2de62033.efi?version=v4"
    # EFI_FILE_URL="https://bootstrap.grid.tf/uefi/${ENVIRONMENT}/${FARM}"
    log "Downloading BOOTX64.EFI from ${EFI_FILE_URL}..."
    if ! wget -q "${EFI_FILE_URL}" -O "${MOUNT_POINT}/efi/boot/BOOTX64.EFI"; then
        log "Failed to download BOOTX64.EFI."
        exit 1
    fi

    log "Download successful."

    # Unmount the partition
    log "Unmounting ${MOUNT_POINT}..."
    umount -r "${MOUNT_POINT}" || { log "Failed to unmount ${MOUNT_POINT}."; exit 1; }

    # Manage UEFI boot entries
    manage_boot_entries

    log "Operation completed successfully."
}

# Execute the main function
main "$@"