nato Encode/decode NATO phonetic alphabet

(input, opts = {})=>{
                const alpha = {
                    A: "Alfa",
                    B: "Bravo",
                    C: "Charlie",
                    D: "Delta",
                    E: "Echo",
                    F: "Foxtrot",
                    G: "Golf",
                    H: "Hotel",
                    I: "India",
                    J: "Juliett",
                    K: "Kilo",
                    L: "Lima",
                    M: "Mike",
                    N: "November",
                    O: "Oscar",
                    P: "Papa",
                    Q: "Quebec",
                    R: "Romeo",
                    S: "Sierra",
                    T: "Tango",
                    U: "Uniform",
                    V: "Victor",
                    W: "Whiskey",
                    X: "X-ray",
                    Y: "Yankee",
                    Z: "Zulu"
                };
                const digits = {
                    0: "Zero",
                    1: "One",
                    2: "Two",
                    3: "Three",
                    4: "Four",
                    5: "Five",
                    6: "Six",
                    7: "Seven",
                    8: "Eight",
                    9: "Niner"
                };
                if (opts.decode) {
                    const rev = {};
                    for (const [k, v] of Object.entries(alpha))rev[v.toLowerCase()] = k.toLowerCase();
                    for (const [k, v] of Object.entries(digits))rev[v.toLowerCase()] = k;
                    return input.split("\n").map((line)=>line.split(/\s+/).map((w)=>rev[w.toLowerCase()] ?? w).join("")).join("\n");
                }
                return input.split("\n").map((line)=>[
                        ...line
                    ].map((c)=>{
                        const u = c.toUpperCase();
                        return alpha[u] || digits[c] || c;
                    }).join(" ")).join("\n");
            }