batch renamer

#!/bin/bash

function mvi {

    function do_edit {
        ${EDITOR:-vi} "${newnames}"
    }

    function review {
        local -a LINESA LINESB
        local oldlines=$(wc -l < "${oldnames}")
        local newlines=$(wc -l < "${newnames}")
        if (( oldlines != newlines )); then
            echo "error: filenames count mismatch found, aborting..." >&2
            return 1
        fi
        if egrep -q -e '^$' "${newnames}"; then
            echo "error: found empty lines in input, aborting..." >&2
            return 1
        fi
        echo "Please carefully review the filename changes."
        echo "Hit enter when ready..."
        read -n 1 -s placebo
        while read line; do
            LINESA[${#LINESA[@]}]="${line}"
        done < "${oldnames}"
        while read line; do
            LINESB[${#LINESB[@]}]="${line}"
        done < "${newnames}"
        for ((i=0; i<${#LINESA[@]}; i++)); do
            if [[ "${LINESA[i]}" != "${LINESB[i]}" ]]; then
                echo "${LINESA[i]} -> ${LINESB[i]}"
                DIFFLINES[${#DIFFLINES[@]}]="${LINESA[i]}"
                DIFFLINES[${#DIFFLINES[@]}]="${LINESB[i]}"
            fi
        done > "${tmpnames}"
        ${PAGER:-more} < "${tmpnames}"
    }

    function confirmation {
        echo "Are you sure you want to renames the files like this? [y/n]"
        read -n 1 -s answer
        case ${answer} in
            [yY]) return 0 ;;
            *) return 1 ;;
        esac
    }

    function cancel {
        echo "Re[e]dit or [a]bort?"
        read -n 1 -s answer
        case ${answer} in
            [eE]) return 1 ;;
            *) return 0 ;;
        esac
    }

    function execute {
        for ((i=0; i<${#DIFFLINES[@]}; i+=2)); do
            echo "mv \"${DIFFLINES[i]}\" \"${DIFFLINES[i+1]}\""
        done
    }

    local oldnames=$(mktemp) newnames=$(mktemp) tmpnames=$(mktemp)
    local -a DIFFLINES

    ls -1 >"${oldnames}"
    cp "${oldnames}" "${newnames}"

    while do_edit; do
        review
        confirmation && execute || cancel && break
    done

    # cleanup
    rm "${oldnames}" "${newnames}"
}