function bufferDecode(value) {
    const padding = "=".repeat((4 - (value.length % 4)) % 4);
    const base64 = (value + padding).replace(/-/g, "+").replace(/_/g, "/");
    const raw = window.atob(base64);
    return Uint8Array.from([...raw].map((c) => c.charCodeAt(0)));
}

function bufferEncode(value) {
    return btoa(String.fromCharCode(...new Uint8Array(value)))
        .replace(/\+/g, "-")
        .replace(/\//g, "_")
        .replace(/=+$/, "");
}

async function registerPasskey() {
    const nameInput = document.getElementById("passkeyName");
    const name = nameInput ? nameInput.value.trim() : "Passkey";

    const optionsResp = await fetch("/auth/passkey/register/options", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
    });
    const options = await optionsResp.json();
    if (!optionsResp.ok) throw new Error(options.error || "Ошибка passkey");

    options.challenge = bufferDecode(options.challenge);
    options.user.id = bufferDecode(options.user.id);
    if (options.excludeCredentials) {
        options.excludeCredentials = options.excludeCredentials.map((item) => ({
            ...item,
            id: bufferDecode(item.id),
        }));
    }

    const credential = await navigator.credentials.create({ publicKey: options });
    const verifyResp = await fetch("/auth/passkey/register/verify", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({
            name,
            credential: {
                id: credential.id,
                rawId: bufferEncode(credential.rawId),
                type: credential.type,
                response: {
                    attestationObject: bufferEncode(credential.response.attestationObject),
                    clientDataJSON: bufferEncode(credential.response.clientDataJSON),
                },
            },
        }),
    });
    const result = await verifyResp.json();
    if (!verifyResp.ok) throw new Error(result.error || "Не удалось сохранить passkey");
    window.location.reload();
}

async function loginWithPasskey(username, remember) {
    const optionsResp = await fetch("/auth/passkey/login/options", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ username }),
    });
    const options = await optionsResp.json();
    if (!optionsResp.ok) throw new Error(options.error || "Passkey недоступен");

    options.challenge = bufferDecode(options.challenge);
    if (options.allowCredentials) {
        options.allowCredentials = options.allowCredentials.map((item) => ({
            ...item,
            id: bufferDecode(item.id),
        }));
    }

    const credential = await navigator.credentials.get({ publicKey: options });
    const verifyResp = await fetch("/auth/passkey/login/verify", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({
            remember,
            credential: {
                id: credential.id,
                rawId: bufferEncode(credential.rawId),
                type: credential.type,
                response: {
                    authenticatorData: bufferEncode(credential.response.authenticatorData),
                    clientDataJSON: bufferEncode(credential.response.clientDataJSON),
                    signature: bufferEncode(credential.response.signature),
                    userHandle: credential.response.userHandle
                        ? bufferEncode(credential.response.userHandle)
                        : null,
                },
            },
        }),
    });
    const result = await verifyResp.json();
    if (!verifyResp.ok) throw new Error(result.error || "Ошибка входа");
    window.location.href = result.redirect || "/cabinet/";
}

document.addEventListener("DOMContentLoaded", () => {
    const addBtn = document.getElementById("addPasskeyBtn");
    if (addBtn) {
        addBtn.addEventListener("click", async () => {
            try {
                if (!window.PublicKeyCredential) {
                    alert("Passkey не поддерживается в этом браузере");
                    return;
                }
                await registerPasskey();
            } catch (err) {
                alert(err.message || "Ошибка passkey");
            }
        });
    }

    const loginBtn = document.getElementById("passkeyLoginBtn");
    if (loginBtn) {
        loginBtn.addEventListener("click", async () => {
            const loginInput = document.getElementById("login");
            const remember = document.querySelector('input[name="remember"]')?.checked;
            const username = loginInput ? loginInput.value.trim() : "";
            if (!username) {
                alert("Введите логин или email");
                return;
            }
            try {
                await loginWithPasskey(username, remember);
            } catch (err) {
                alert(err.message || "Ошибка passkey");
            }
        });
    }
});