/*
Copyright 2019-2021 The Matrix.org Foundation C.I.C.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

import React, { ReactNode } from "react";
import {
    AutoDiscovery,
    AutoDiscoveryError,
    ClientConfig,
    discoverAndValidateOIDCIssuerWellKnown,
    IClientWellKnown,
    MatrixClient,
    MatrixError,
    OidcClientConfig,
} from "matrix-js-sdk/src/matrix";
import { logger } from "matrix-js-sdk/src/logger";

import { _t, _td, TranslationKey, UserFriendlyError } from "../languageHandler";
import SdkConfig from "../SdkConfig";
import { ValidatedServerConfig } from "./ValidatedServerConfig";

const LIVELINESS_DISCOVERY_ERRORS: AutoDiscoveryError[] = [
    AutoDiscovery.ERROR_INVALID_HOMESERVER,
    AutoDiscovery.ERROR_INVALID_IDENTITY_SERVER,
];

export interface IAuthComponentState {
    serverIsAlive: boolean;
    serverErrorIsFatal: boolean;
    serverDeadError?: ReactNode;
}

const AutoDiscoveryErrors = Object.values(AutoDiscoveryError);

const isAutoDiscoveryError = (err: unknown): err is AutoDiscoveryError => {
    return AutoDiscoveryErrors.includes(err as AutoDiscoveryError);
};

const mapAutoDiscoveryErrorTranslation = (err: AutoDiscoveryError): TranslationKey => {
    switch (err) {
        case AutoDiscoveryError.GenericFailure:
            return _td("auth|autodiscovery_invalid");
        case AutoDiscoveryError.Invalid:
            return _td("auth|autodiscovery_generic_failure");
        case AutoDiscoveryError.InvalidHsBaseUrl:
            return _td("auth|autodiscovery_invalid_hs_base_url");
        case AutoDiscoveryError.InvalidHomeserver:
            return _td("auth|autodiscovery_invalid_hs");
        case AutoDiscoveryError.InvalidIsBaseUrl:
            return _td("auth|autodiscovery_invalid_is_base_url");
        case AutoDiscoveryError.InvalidIdentityServer:
            return _td("auth|autodiscovery_invalid_is");
        case AutoDiscoveryError.InvalidIs:
            return _td("auth|autodiscovery_invalid_is_response");
        case AutoDiscoveryError.MissingWellknown:
            return _td("auth|autodiscovery_no_well_known");
        case AutoDiscoveryError.InvalidJson:
            return _td("auth|autodiscovery_invalid_json");
        case AutoDiscoveryError.HomeserverTooOld:
            return _td("auth|autodiscovery_hs_incompatible");
    }
};

export default class AutoDiscoveryUtils {
    /**
     * Checks if a given error or error message is considered an error
     * relating to the liveliness of the server. Must be an error returned
     * from this AutoDiscoveryUtils class.
     * @param {string | Error} error The error to check
     * @returns {boolean} True if the error is a liveliness error.
     */
    public static isLivelinessError(error: unknown): boolean {
        if (!error) return false;
        let msg: unknown = error;
        if (error instanceof UserFriendlyError) {
            msg = error.cause;
        } else if (error instanceof Error) {
            msg = error.message;
        }
        return LIVELINESS_DISCOVERY_ERRORS.includes(msg as AutoDiscoveryError);
    }

    /**
     * Gets the common state for auth components (login, registration, forgot
     * password) for a given validation error.
     * @param {Error} err The error encountered.
     * @param {string} pageName The page for which the error should be customized to. See
     * implementation for known values.
     * @returns {*} The state for the component, given the error.
     */
    public static authComponentStateForError(err: unknown, pageName = "login"): IAuthComponentState {
        if (!err) {
            return {
                serverIsAlive: true,
                serverErrorIsFatal: false,
                serverDeadError: null,
            };
        }
        let title = _t("cannot_reach_homeserver");
        let body: ReactNode = _t("cannot_reach_homeserver_detail");
        if (!AutoDiscoveryUtils.isLivelinessError(err)) {
            const brand = SdkConfig.get().brand;
            title = _t("auth|misconfigured_title", { brand });
            body = _t(
                "auth|misconfigured_body",
                {
                    brand,
                },
                {
                    a: (sub) => {
                        return (
                            <a
                                href="https://github.com/vector-im/element-web/blob/master/docs/config.md"
                                target="_blank"
                                rel="noreferrer noopener"
                            >
                                {sub}
                            </a>
                        );
                    },
                },
            );
        }

        let isFatalError = true;
        const errorMessage = err instanceof Error ? err.message : err;
        if (errorMessage === AutoDiscovery.ERROR_INVALID_IDENTITY_SERVER) {
            isFatalError = false;
            title = _t("auth|failed_connect_identity_server");

            // It's annoying having a ladder for the third word in the same sentence, but our translations
            // don't make this easy to avoid.
            if (pageName === "register") {
                body = _t("auth|failed_connect_identity_server_register");
            } else if (pageName === "reset_password") {
                body = _t("auth|failed_connect_identity_server_reset_password");
            } else {
                body = _t("auth|failed_connect_identity_server_other");
            }
        }

        return {
            serverIsAlive: false,
            serverErrorIsFatal: isFatalError,
            serverDeadError: (
                <div>
                    <strong>{title}</strong>
                    <div>{body}</div>
                </div>
            ),
        };
    }

    /**
     * Validates a server configuration, using a pair of URLs as input.
     * @param {string} homeserverUrl The homeserver URL.
     * @param {string} identityUrl The identity server URL.
     * @param {boolean} syntaxOnly If true, errors relating to liveliness of the servers will
     * not be raised.
     * @returns {Promise<ValidatedServerConfig>} Resolves to the validated configuration.
     */
    public static async validateServerConfigWithStaticUrls(
        homeserverUrl: string,
        identityUrl?: string,
        syntaxOnly = false,
    ): Promise<ValidatedServerConfig> {
        if (!homeserverUrl) {
            throw new UserFriendlyError("auth|no_hs_url_provided");
        }

        const wellknownConfig: IClientWellKnown = {
            "m.homeserver": {
                base_url: homeserverUrl,
            },
        };

        if (identityUrl) {
            wellknownConfig["m.identity_server"] = {
                base_url: identityUrl,
            };
        }

        const result = await AutoDiscovery.fromDiscoveryConfig(wellknownConfig);

        const url = new URL(homeserverUrl);
        const serverName = url.hostname;

        return AutoDiscoveryUtils.buildValidatedConfigFromDiscovery(serverName, result, syntaxOnly, true);
    }

    /**
     * Validates a server configuration, using a homeserver domain name as input.
     * @param {string} serverName The homeserver domain name (eg: "matrix.org") to validate.
     * @returns {Promise<ValidatedServerConfig>} Resolves to the validated configuration.
     */
    public static async validateServerName(serverName: string): Promise<ValidatedServerConfig> {
        const result = await AutoDiscovery.findClientConfig(serverName);
        return AutoDiscoveryUtils.buildValidatedConfigFromDiscovery(serverName, result);
    }

    /**
     * Validates a server configuration, using a pre-calculated AutoDiscovery result as
     * input.
     * @param {string} serverName The domain name the AutoDiscovery result is for.
     * @param {*} discoveryResult The AutoDiscovery result.
     * @param {boolean} syntaxOnly If true, errors relating to liveliness of the servers will not be raised.
     * @param {boolean} isSynthetic If true, then the discoveryResult was synthesised locally.
     * @returns {Promise<ValidatedServerConfig>} Resolves to the validated configuration.
     */
    public static async buildValidatedConfigFromDiscovery(
        serverName?: string,
        discoveryResult?: ClientConfig,
        syntaxOnly = false,
        isSynthetic = false,
    ): Promise<ValidatedServerConfig> {
        if (!discoveryResult?.["m.homeserver"]) {
            // This shouldn't happen without major misconfiguration, so we'll log a bit of information
            // in the log so we can find this bit of code but otherwise tell the user "it broke".
            logger.error("Ended up in a state of not knowing which homeserver to connect to.");
            throw new UserFriendlyError("auth|autodiscovery_unexpected_error_hs");
        }

        const hsResult = discoveryResult["m.homeserver"];
        const isResult = discoveryResult["m.identity_server"];

        const defaultConfig = SdkConfig.get("validated_server_config");

        // Validate the identity server first because an invalid identity server causes
        // an invalid homeserver, which may not be picked up correctly.

        // Note: In the cases where we rely on the default IS from the config (namely
        // lack of identity server provided by the discovery method), we intentionally do not
        // validate it. This has already been validated and this helps some off-the-grid usage
        // of Element.
        let preferredIdentityUrl = defaultConfig && defaultConfig["isUrl"];
        if (isResult && isResult.state === AutoDiscovery.SUCCESS) {
            preferredIdentityUrl = isResult["base_url"] ?? undefined;
        } else if (isResult && isResult.state !== AutoDiscovery.PROMPT) {
            logger.error("Error determining preferred identity server URL:", isResult);
            if (isResult.state === AutoDiscovery.FAIL_ERROR) {
                if (isAutoDiscoveryError(isResult.error)) {
                    throw new UserFriendlyError(mapAutoDiscoveryErrorTranslation(isResult.error), {
                        cause: hsResult.error,
                    });
                }
                throw new UserFriendlyError("auth|autodiscovery_unexpected_error_is");
            } // else the error is not related to syntax - continue anyways.

            // rewrite homeserver error since we don't care about problems
            hsResult.error = AutoDiscovery.ERROR_INVALID_IDENTITY_SERVER;

            // Also use the user's supplied identity server if provided
            if (isResult["base_url"]) preferredIdentityUrl = isResult["base_url"];
        }

        if (hsResult.state !== AutoDiscovery.SUCCESS) {
            logger.error("Error processing homeserver config:", hsResult);
            if (!syntaxOnly || !AutoDiscoveryUtils.isLivelinessError(hsResult.error)) {
                if (isAutoDiscoveryError(hsResult.error)) {
                    throw new UserFriendlyError(mapAutoDiscoveryErrorTranslation(hsResult.error), {
                        cause: hsResult.error,
                    });
                }
                throw new UserFriendlyError("auth|autodiscovery_unexpected_error_hs");
            } // else the error is not related to syntax - continue anyways.
        }

        const preferredHomeserverUrl = hsResult["base_url"];

        if (!preferredHomeserverUrl) {
            logger.error("No homeserver URL configured");
            throw new UserFriendlyError("auth|autodiscovery_unexpected_error_hs");
        }

        let preferredHomeserverName = serverName ?? hsResult["server_name"];

        const url = new URL(preferredHomeserverUrl);
        if (!preferredHomeserverName) preferredHomeserverName = url.hostname;

        // It should have been set by now, so check it
        if (!preferredHomeserverName) {
            logger.error("Failed to parse homeserver name from homeserver URL");
            throw new UserFriendlyError("auth|autodiscovery_unexpected_error_hs");
        }

        // This isn't inherently auto-discovery but used to be in an earlier incarnation of the MSC,
        // and shuttling the data together makes a lot of sense
        let delegatedAuthentication: OidcClientConfig | undefined;
        let delegatedAuthenticationError: Error | undefined;
        try {
            const tempClient = new MatrixClient({ baseUrl: preferredHomeserverUrl });
            const { issuer } = await tempClient.getAuthIssuer();
            delegatedAuthentication = await discoverAndValidateOIDCIssuerWellKnown(issuer);
        } catch (e) {
            if (e instanceof MatrixError && e.httpStatus === 404 && e.errcode === "M_UNRECOGNIZED") {
                // 404 M_UNRECOGNIZED means the server does not support OIDC
            } else {
                delegatedAuthenticationError = e as Error;
            }
        }

        return {
            hsUrl: preferredHomeserverUrl,
            hsName: preferredHomeserverName,
            hsNameIsDifferent: url.hostname !== preferredHomeserverName,
            isUrl: preferredIdentityUrl,
            isDefault: false,
            warning: hsResult.error ?? delegatedAuthenticationError ?? null,
            isNameResolvable: !isSynthetic,
            delegatedAuthentication,
        } as ValidatedServerConfig;
    }
}