#!/usr/bin/env bash
set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
BACKUP_DIR="${SCRIPT_DIR}/backups"

show_diff() {
    local source_dir="$1"
    echo ""
    echo "==================== Changes Preview (Diff) ===================="
    local changes_found=0

    while IFS= read -r -d '' item; do
        rel_path="${item#"${source_dir}"/}"
        dest_item="${HOME}/${rel_path}"

        if [ -d "${item}" ]; then
            continue
        fi

        if [ ! -e "${dest_item}" ]; then
            changes_found=1
            echo -e "\n\033[1;32m[NEW FILE]\033[0m ~/${rel_path}"
        else
            if ! cmp -s "${item}" "${dest_item}"; then
                changes_found=1
                echo -e "\n\033[1;33m[MODIFIED]\033[0m ~/${rel_path}"
                if command -v git &>/dev/null; then
                    git diff --no-index --color "${dest_item}" "${item}" || true
                else
                    diff -u --color=always "${dest_item}" "${item}" || true
                fi
            fi
        fi
    done < <(find "${source_dir}" -type f -print0)

    if [ "${changes_found}" -eq 0 ]; then
        echo -e "\n\033[1;32mNo differences detected. Current configuration matches the backup exactly.\033[0m"
    fi
    echo "================================================================"
    echo ""
}

ARCHIVE_PATH=""

# 1. Check positional argument
if [ $# -ge 1 ] && [ -n "$1" ]; then
    ARCHIVE_PATH="$1"
# 2. Check if piped via stdin
elif [ ! -t 0 ]; then
    read -r ARCHIVE_PATH || true
fi

# 3. Interactive prompt / selection menu if no input given
if [ -z "${ARCHIVE_PATH}" ]; then
    if [ ! -d "${BACKUP_DIR}" ]; then
        echo "Error: No backups directory found at ${BACKUP_DIR}"
        exit 1
    fi

    mapfile -t AVAILABLE_BACKUPS < <(find "${BACKUP_DIR}" -maxdepth 1 -name "konsole_backup_*.zip" | sort -r)

    if [ "${#AVAILABLE_BACKUPS[@]}" -eq 0 ]; then
        echo "Error: No backup archives found in ${BACKUP_DIR}."
        exit 1
    fi

    echo "Available Konsole backups:"
    for i in "${!AVAILABLE_BACKUPS[@]}"; do
        echo " [$((i + 1))] $(basename "${AVAILABLE_BACKUPS[$i]}")"
    done
    echo " [q] Quit"

    read -r -p "Select a backup to restore [1-${#AVAILABLE_BACKUPS[@]}]: " choice < /dev/tty
    if [[ "${choice}" =~ ^[0-9]+$ ]] && [ "${choice}" -ge 1 ] && [ "${choice}" -le "${#AVAILABLE_BACKUPS[@]}" ]; then
        ARCHIVE_PATH="${AVAILABLE_BACKUPS[$((choice - 1))]}"
    else
        echo "Aborted."
        exit 0
    fi
fi

# Expand relative paths
if [[ "${ARCHIVE_PATH}" != /* ]]; then
    if [ -f "${BACKUP_DIR}/${ARCHIVE_PATH}" ]; then
        ARCHIVE_PATH="${BACKUP_DIR}/${ARCHIVE_PATH}"
    elif [ -f "./${ARCHIVE_PATH}" ]; then
        ARCHIVE_PATH="$(pwd)/${ARCHIVE_PATH}"
    fi
fi

if [ ! -f "${ARCHIVE_PATH}" ]; then
    echo "Error: Backup file not found: ${ARCHIVE_PATH}"
    exit 1
fi

echo "Selected backup archive: ${ARCHIVE_PATH}"

# Extract to temporary staging directory
TEMP_DIR="$(mktemp -d)"
trap 'rm -rf "${TEMP_DIR}"' EXIT

unzip -q -o "${ARCHIVE_PATH}" -d "${TEMP_DIR}"

# Interactive confirmation loop (allows viewing diffs)
while true; do
    echo ""
    echo "Konsole configuration files to be restored:"
    find "${TEMP_DIR}" -mindepth 1 -maxdepth 3 | while read -r f; do
        rel="${f#"${TEMP_DIR}"/}"
        echo "  - ~/${rel}"
    done
    echo ""

    if [ -t 0 ]; then
        INPUT_SRC="/dev/stdin"
    else
        INPUT_SRC="/dev/tty"
    fi

    read -r -p "Choose action: [r] Restore / [d] View Diff / [c] Cancel: " action < "${INPUT_SRC}"

    case "${action,,}" in
        r|y|yes)
            echo "Restoring configuration files..."
            cp -a "${TEMP_DIR}/." "${HOME}/"
            echo -e "\033[1;32mKonsole configurations restored successfully from $(basename "${ARCHIVE_PATH}")!\033[0m"
            echo "Note: If Konsole is currently running, please restart it to apply all settings."
            break
            ;;
        d|diff)
            show_diff "${TEMP_DIR}"
            ;;
        c|q|n|no|cancel)
            echo "Restoration cancelled."
            exit 0
            ;;
        *)
            echo "Invalid option. Please enter 'r', 'd', or 'c'."
            ;;
    esac
done