const admin = require("firebase-admin");
const { HttpsError } = require("firebase-functions/https");
const Stripe = require("stripe");
const { URL } = require("url");

const {
  STRIPE_SECRET_KEY = "",
  STRIPE_RETURN_URL = "",
  STRIPE_PORTAL_CONFIGURATION = "",
  STRIPE_MODE: CONFIG_STRIPE_MODE,
} = require("../config/keys");

const STRIPE_MODE =
  typeof CONFIG_STRIPE_MODE === "string" && CONFIG_STRIPE_MODE.trim()
    ? CONFIG_STRIPE_MODE.trim()
    : "test";

const requireEnv = (key) => {
  const value = process.env?.[key];
  if (typeof value === "string" && value.trim()) {
    return value.trim();
  }
  throw new Error(`${key} not configured`);
};

const STRIPE_API_VERSION = "2023-10-16";
const DEFAULT_TEST_RETURN_URL = "http://localhost:8081";
const ALLOWED_RETURN_SCHEMES = ["http", "https", "minuit"];

let cachedStripeClient = null;
let cachedPortalConfigurationId = null;

const resolveStripeSecretKey = () => {
  const inlineKey =
    typeof STRIPE_SECRET_KEY === "string" ? STRIPE_SECRET_KEY.trim() : "";

  if (inlineKey) {
    return inlineKey;
  }

  const required = requireEnv("STRIPE_SECRET_KEY");
  if (typeof required === "string" && required.trim()) {
    return required.trim();
  }

  throw new Error("STRIPE_SECRET_KEY not configured");
};

const getStripeClient = () => {
  if (cachedStripeClient) {
    return cachedStripeClient;
  }

  let secretKey;
  try {
    secretKey = resolveStripeSecretKey();
  } catch (error) {
    console.error("[getStripeClient] Missing STRIPE_SECRET_KEY", error);
    throw new HttpsError(
      "failed-precondition",
      "Stripe n’est pas configuré. Ajoute STRIPE_SECRET_KEY pour activer cette fonctionnalité.",
    );
  }

  cachedStripeClient = new Stripe(secretKey, {
    apiVersion: STRIPE_API_VERSION,
  });

  return cachedStripeClient;
};

const getReturnBaseUrl = () => {
  const resolveBase = () => {
    if (STRIPE_RETURN_URL) {
      return STRIPE_RETURN_URL;
    }
    if (STRIPE_MODE !== "prod") {
      return DEFAULT_TEST_RETURN_URL;
    }
    return requireEnv("STRIPE_RETURN_URL");
  };

  const rawBase = resolveBase();
  const sanitizedBase = typeof rawBase === "string" ? rawBase.trim() : "";
  if (!sanitizedBase) {
    if (STRIPE_MODE !== "prod") {
      return DEFAULT_TEST_RETURN_URL;
    }
    throw new Error("STRIPE_RETURN_URL not configured");
  }

  return sanitizedBase.endsWith("/")
    ? sanitizedBase.slice(0, -1)
    : sanitizedBase;
};

const sanitizeReturnUrl = (value) => {
  if (typeof value !== "string") {
    return null;
  }

  const trimmed = value.trim();
  if (!trimmed) {
    return null;
  }

  const validateScheme = (scheme) => {
    if (!ALLOWED_RETURN_SCHEMES.includes(scheme)) {
      throw new HttpsError(
        "invalid-argument",
        `Le schéma d'URL "${scheme}" n'est pas autorisé pour les retours Stripe.`,
      );
    }
  };

  try {
    const parsedUrl = new URL(trimmed);
    const scheme = parsedUrl.protocol.replace(":", "").toLowerCase();
    validateScheme(scheme);
    return trimmed;
  } catch (_error) {
    const schemeMatch = trimmed.match(/^([a-z][a-z0-9+\-.]*):\/\//i);
    if (schemeMatch && schemeMatch[1]) {
      const scheme = schemeMatch[1].toLowerCase();
      validateScheme(scheme);
      return trimmed;
    }
    throw new HttpsError(
      "invalid-argument",
      `URL de retour Stripe invalide: ${trimmed}`,
    );
  }
};

const getReturnUrls = (overrides) => {
  if (overrides && typeof overrides === "object") {
    const successOverride = sanitizeReturnUrl(overrides.successUrl);
    const cancelOverride = sanitizeReturnUrl(overrides.cancelUrl);

    if (!successOverride) {
      throw new HttpsError(
        "invalid-argument",
        "successUrl est requis pour configurer les retours Stripe.",
      );
    }

    return {
      successUrl: successOverride,
      cancelUrl: cancelOverride || successOverride,
    };
  }

  const baseUrl = getReturnBaseUrl();

  const joinPath = (url, path) => {
    const trimmedUrl = url.endsWith("/") ? url.slice(0, -1) : url;
    const trimmedPath = path.startsWith("/") ? path.slice(1) : path;
    return `${trimmedUrl}/${trimmedPath}`;
  };

  const appendQuery = (url, query) =>
    url.includes("?") ? `${url}&${query}` : `${url}?${query}`;

  const successBase = joinPath(baseUrl, "payment-success");
  const cancelBase = joinPath(baseUrl, "payment-error");

  return {
    successUrl: appendQuery(successBase, "session_id={CHECKOUT_SESSION_ID}"),
    cancelUrl: appendQuery(cancelBase, "session_id={CHECKOUT_SESSION_ID}"),
  };
};

const normalizeBoolean = (value) => value === true;

const buildCheckoutLineItems = async (productList, { stripe } = {}) => {
  if (!Array.isArray(productList) || productList.length === 0) {
    throw new HttpsError(
      "invalid-argument",
      "Au moins un produit est requis pour créer une session de paiement.",
    );
  }

  const lineItems = [];
  const summary = [];
  let hasSubscription = false;

  for (let index = 0; index < productList.length; index += 1) {
    const rawItem = productList[index];
    const item = rawItem && typeof rawItem === "object" ? rawItem : {};

    const isRenewable = normalizeBoolean(item.isRenewable);
    const rawQuantity =
      typeof item.quantity === "number" && Number.isFinite(item.quantity)
        ? item.quantity
        : parseInt(item.quantity, 10);
    const quantity =
      Number.isFinite(rawQuantity) && rawQuantity > 0 ? rawQuantity : 1;

    const priceId = typeof item.priceID === "string" ? item.priceID.trim() : "";

    if (isRenewable && !priceId) {
      throw new HttpsError(
        "invalid-argument",
        `Un price ID Stripe est requis pour l'élément ${index + 1} (abonnement).`,
      );
    }

    if (priceId) {
      let stripePrice = null;
      if (stripe) {
        try {
          stripePrice = await stripe.prices.retrieve(priceId);
        } catch (error) {
          console.error(
            "[buildCheckoutLineItems] Unable to retrieve price",
            priceId,
            error,
          );
          throw new HttpsError(
            "invalid-argument",
            `Le price ID "${priceId}" est introuvable (élément ${index + 1}).`,
          );
        }
      }

      const priceIsRecurring =
        stripePrice?.type === "recurring" || !!stripePrice?.recurring;
      if (isRenewable && !priceIsRecurring) {
        throw new HttpsError(
          "invalid-argument",
          `Le price ID "${priceId}" n'est pas compatible avec un abonnement.`,
        );
      }

      const resolvedIsRenewable = priceIsRecurring ? true : isRenewable;

      if (resolvedIsRenewable) {
        hasSubscription = true;
      }

      lineItems.push({
        price: priceId,
        quantity,
      });
      summary.push({
        type: "price",
        priceID: priceId,
        quantity,
        isRenewable: resolvedIsRenewable,
      });
      continue;
    }

    const rawUnitAmount = Number(item.unitAmount);
    const unitAmount = Math.round(rawUnitAmount);
    if (!Number.isFinite(unitAmount) || unitAmount <= 0) {
      throw new HttpsError(
        "invalid-argument",
        `Le montant indiqué pour l'élément ${index + 1} est invalide.`,
      );
    }

    const currency =
      typeof item.currency === "string"
        ? item.currency.trim().toLowerCase()
        : "eur";

    if (!/^[a-z]{3}$/.test(currency)) {
      throw new HttpsError(
        "invalid-argument",
        `La devise indiquée pour l'élément ${index + 1} est invalide.`,
      );
    }

    const label =
      typeof item.label === "string" && item.label.trim()
        ? item.label.trim()
        : "Paiement ponctuel";

    lineItems.push({
      price_data: {
        currency,
        product_data: {
          name: label,
        },
        unit_amount: unitAmount,
      },
      quantity,
    });

    summary.push({
      type: "custom",
      currency,
      unitAmount,
      quantity,
      isRenewable: false,
    });
  }

  if (hasSubscription) {
    const hasNonSubscription = summary.some((item) => !item.isRenewable);
    if (hasNonSubscription) {
      throw new HttpsError(
        "invalid-argument",
        "Impossible de mélanger abonnements et paiements ponctuels dans une seule session Checkout.",
      );
    }
  }

  return { lineItems, summary, hasSubscription };
};

const ensureStripeCustomer = async ({
  uid,
  stripe,
  refsList,
  createIfMissing = true,
}) => {
  if (!uid) {
    return { customerId: null, userData: null };
  }

  const userRef = refsList?.users?.doc(uid);
  const snapshot = userRef ? await userRef.get() : null;
  const userData = snapshot?.exists ? snapshot.data() : null;

  let customerId = userData?.stripeCustomerId;
  if (customerId) {
    return { customerId, userData };
  }

  if (!createIfMissing) {
    return { customerId: null, userData };
  }

  let authRecord = null;
  try {
    authRecord = await admin.auth().getUser(uid);
  } catch (error) {
    console.warn(
      "[ensureStripeCustomer] Impossible de récupérer auth user",
      error,
    );
  }

  const email = userData?.email || authRecord?.email || undefined;
  const nameFromProfile = [userData?.firstName, userData?.lastName]
    .filter(Boolean)
    .join(" ")
    .trim();
  const name = nameFromProfile || authRecord?.displayName || undefined;

  const customer = await stripe.customers.create({
    email,
    name,
    metadata: {
      firebaseUID: uid,
      appMode: STRIPE_MODE || "test",
    },
  });

  customerId = customer.id;

  if (userRef) {
    await userRef.set(
      {
        stripeCustomerId: customerId,
      },
      { merge: true },
    );
  }

  return {
    customerId,
    userData: { ...userData, stripeCustomerId: customerId },
  };
};

const formatCheckoutSessionResponse = (session) => ({
  id: session.id,
  object: session.object,
  customer: session.customer,
  customer_details: session.customer_details,
  url: session.url,
  mode: session.mode,
  status: session.status,
  payment_status: session.payment_status,
  currency: session.currency,
  amount_subtotal: session.amount_subtotal,
  amount_total: session.amount_total,
  created: session.created,
  expires_at: session.expires_at,
  client_secret: session.client_secret || null,
});

const getPortalConfigurationId = async (stripe) => {
  if (STRIPE_PORTAL_CONFIGURATION) {
    return STRIPE_PORTAL_CONFIGURATION;
  }

  if (cachedPortalConfigurationId) {
    return cachedPortalConfigurationId;
  }

  if (
    !stripe ||
    typeof stripe.billingPortal?.configurations?.list !== "function"
  ) {
    throw new HttpsError(
      "internal",
      "Client Stripe indisponible pour la configuration du portail.",
    );
  }

  try {
    const configurations = await stripe.billingPortal.configurations.list({
      limit: 100,
    });

    const defaultConfiguration =
      configurations.data.find((config) => config.is_default) ||
      configurations.data.find((config) => config.active);

    if (defaultConfiguration?.id) {
      cachedPortalConfigurationId = defaultConfiguration.id;
      return cachedPortalConfigurationId;
    }
  } catch (error) {
    console.warn(
      "[getPortalConfigurationId] Impossible de lister les configurations de portail",
      error?.message || error,
    );
  }

  try {
    const defaultReturnUrl = getReturnBaseUrl();
    const createdConfiguration =
      await stripe.billingPortal.configurations.create({
        default_return_url: defaultReturnUrl,
        business_profile: {
          headline: "Minuit Starter",
        },
      });

    if (createdConfiguration?.id) {
      cachedPortalConfigurationId = createdConfiguration.id;
      return cachedPortalConfigurationId;
    }
  } catch (error) {
    console.warn(
      "[getPortalConfigurationId] Impossible de créer une configuration de portail par défaut",
      error?.message || error,
    );
  }

  return null;
};

const mapStripeErrorToHttps = (error, fallbackMessage) => {
  const message =
    error?.raw?.message ||
    error?.message ||
    fallbackMessage ||
    "Erreur Stripe.";
  const statusCode = error?.statusCode || error?.raw?.statusCode;
  const isClientError =
    typeof statusCode === "number" && statusCode >= 400 && statusCode < 500;

  const code = isClientError ? "failed-precondition" : "internal";
  return new HttpsError(code, message);
};

module.exports = {
  getStripeClient,
  getReturnUrls,
  getReturnBaseUrl,
  buildCheckoutLineItems,
  ensureStripeCustomer,
  formatCheckoutSessionResponse,
  getPortalConfigurationId,
  mapStripeErrorToHttps,
};