package com.commafeed;

import com.commafeed.backend.feed.FeedRefreshIntervalCalculator;

import io.quarkus.runtime.annotations.ConfigDocSection;
import io.quarkus.runtime.annotations.ConfigPhase;
import io.quarkus.runtime.annotations.ConfigRoot;
import io.quarkus.runtime.configuration.MemorySize;
import io.smallrye.config.ConfigMapping;
import io.smallrye.config.WithDefault;

import jakarta.validation.constraints.Min;
import jakarta.validation.constraints.Positive;

import java.time.Duration;
import java.time.Instant;
import java.util.Optional;

/**
 * CommaFeed configuration
 *
 * <p>Default values are for production, they can be overridden in application.properties for other
 * profiles
 */
@ConfigMapping(prefix = "commafeed")
@ConfigRoot(phase = ConfigPhase.RUN_TIME)
public interface CommaFeedConfiguration {
    /**
     * Whether to expose a robots.txt file that disallows web crawlers and search engine indexers.
     */
    @WithDefault("true")
    boolean hideFromWebCrawlers();

    /**
     * If enabled, images in feed entries will be proxied through the server instead of accessed
     * directly by the browser.
     *
     * <p>This is useful if commafeed is accessed through a restricting proxy that blocks some feeds
     * that are followed.
     */
    @WithDefault("false")
    boolean imageProxyEnabled();

    /**
     * Enable password recovery via email.
     *
     * <p>Quarkus mailer will need to be configured.
     */
    @WithDefault("false")
    boolean passwordRecoveryEnabled();

    /**
     * The base URL of the application to use in the password recovery link in the email. We can't
     * use the URL sent by the browser of the user because of malicious Host header injection
     * attacks.
     */
    Optional<String> passwordRecoveryPublicBaseUrl();

    /** Message displayed in a notification at the bottom of the page. */
    Optional<String> announcement();

    /** Google Auth key for fetching Youtube channel favicons. */
    Optional<String> googleAuthKey();

    /** HTTP client configuration */
    @ConfigDocSection
    HttpClient httpClient();

    /** Feed refresh engine settings. */
    @ConfigDocSection
    FeedRefresh feedRefresh();

    /** Push notification settings. */
    @ConfigDocSection
    PushNotifications pushNotifications();

    /** Database settings. */
    @ConfigDocSection
    Database database();

    /** Users settings. */
    @ConfigDocSection
    Users users();

    /** Websocket settings. */
    @ConfigDocSection
    Websocket websocket();

    /**
     * Duration to wait for the feed refresh engine and the task scheduler to stop when the
     * application is shutting down.
     */
    @WithDefault("2s")
    Duration shutdownTimeout();

    interface HttpClient {
        /**
         * User-Agent string that will be used by the http client, leave empty for the default one.
         */
        Optional<String> userAgent();

        /** Time to wait for a connection to be established. */
        @WithDefault("5s")
        Duration connectTimeout();

        /** Time to wait for SSL handshake to complete. */
        @WithDefault("5s")
        Duration sslHandshakeTimeout();

        /** Time to wait between two packets before timeout. */
        @WithDefault("10s")
        Duration socketTimeout();

        /** Time to wait for the full response to be received. */
        @WithDefault("10s")
        Duration responseTimeout();

        /** Time to live for a connection in the pool. */
        @WithDefault("30s")
        Duration connectionTimeToLive();

        /** Time between eviction runs for idle connections. */
        @WithDefault("1m")
        Duration idleConnectionsEvictionInterval();

        /**
         * If a feed is larger than this, it will be discarded to prevent memory issues while
         * parsing the feed.
         */
        @WithDefault("5M")
        MemorySize maxResponseSize();

        /**
         * Prevent access to local addresses to mitigate server-side request forgery (SSRF) attacks,
         * which could potentially expose internal resources.
         *
         * <p>You may want to enable this if you host a public instance of CommaFeed with
         * registrations open.
         */
        @WithDefault("true")
        boolean blockLocalAddresses();

        /** HTTP client cache configuration */
        @ConfigDocSection
        HttpClientCache cache();
    }

    interface HttpClientCache {
        /**
         * Whether to enable the cache. This cache is used to avoid spamming feeds in short bursts
         * (e.g. when subscribing to a feed for the first time or when clicking "fetch all my feeds
         * now").
         */
        @WithDefault("true")
        boolean enabled();

        /** Maximum amount of memory the cache can use. */
        @WithDefault("10M")
        MemorySize maximumMemorySize();

        /** Duration after which an entry is removed from the cache. */
        @WithDefault("1m")
        Duration expiration();
    }

    interface FeedRefresh {
        /** Default amount of time CommaFeed will wait before refreshing a feed. */
        @WithDefault("5m")
        Duration interval();

        /**
         * Maximum amount of time CommaFeed will wait before refreshing a feed. This is used as an
         * upper bound when:
         *
         * <ul>
         *   <li>an error occurs while refreshing a feed and we're backing off exponentially
         *   <li>we receive a Cache-Control header from the feed
         *   <li>we receive a Retry-After header from the feed
         * </ul>
         */
        @WithDefault("4h")
        Duration maxInterval();

        /**
         * If enabled, CommaFeed will calculate the next refresh time based on the feed's average
         * time between entries and the time since the last entry was published. The interval will
         * be sometimes between the default refresh interval (`commafeed.feed-refresh.interval`) and
         * the maximum refresh interval (`commafeed.feed-refresh.max-interval`).
         *
         * <p>See {@link FeedRefreshIntervalCalculator} for details.
         */
        @WithDefault("true")
        boolean intervalEmpirical();

        /** Feed refresh engine error handling settings. */
        @ConfigDocSection
        FeedRefreshErrorHandling errors();

        /** Amount of http threads used to fetch feeds. */
        @Min(1)
        @WithDefault("3")
        int httpThreads();

        /** Amount of threads used to insert new entries in the database. */
        @Min(1)
        @WithDefault("1")
        int databaseThreads();

        /**
         * Duration after which a user is considered inactive. Feeds for inactive users are not
         * refreshed until they log in again.
         *
         * <p>0 to disable.
         */
        @WithDefault("0")
        Duration userInactivityPeriod();

        /**
         * Duration after which the evaluation of a filtering expresion to mark an entry as read is
         * considered to have timed out.
         */
        @WithDefault("500ms")
        Duration filteringExpressionEvaluationTimeout();

        /**
         * Duration after which the "Fetch all my feeds now" action is available again after use to
         * avoid spamming feeds.
         */
        @WithDefault("0")
        Duration forceRefreshCooldownDuration();
    }

    interface PushNotifications {
        /** Whether to enable push notifications to notify users of new entries in their feeds. */
        @WithDefault("true")
        boolean enabled();

        /** Amount of threads used to send external notifications about new entries. */
        @Min(1)
        @WithDefault("5")
        int threads();

        /**
         * Maximum amount of notifications that can be queued before new notifications are
         * discarded.
         */
        @Min(1)
        @WithDefault("100")
        int queueCapacity();
    }

    interface FeedRefreshErrorHandling {
        /** Number of retries before backoff is applied. */
        @Min(0)
        @WithDefault("3")
        int retriesBeforeBackoff();

        /**
         * Duration to wait before retrying after an error. Will be multiplied by the number of
         * errors since the last successful fetch.
         */
        @WithDefault("1h")
        Duration backoffInterval();
    }

    interface Database {
        /**
         * Timeout applied to all database queries.
         *
         * <p>0 to disable.
         */
        @WithDefault("0")
        Duration queryTimeout();

        /** Database cleanup settings. */
        @ConfigDocSection
        Cleanup cleanup();

        interface Cleanup {
            /**
             * Maximum age of feed entries in the database. Older entries will be deleted.
             *
             * <p>0 to disable.
             */
            @WithDefault("365d")
            Duration entriesMaxAge();

            /**
             * Maximum age of feed entry statuses (read/unread) in the database. Older statuses will
             * be deleted.
             *
             * <p>0 to disable.
             */
            @WithDefault("0")
            Duration statusesMaxAge();

            /**
             * Maximum number of entries per feed to keep in the database.
             *
             * <p>0 to disable.
             */
            @WithDefault("500")
            int maxFeedCapacity();

            /**
             * Limit the number of feeds a user can subscribe to.
             *
             * <p>0 to disable.
             */
            @WithDefault("0")
            int maxFeedsPerUser();

            /** Rows to delete per query while cleaning up old entries. */
            @Positive
            @WithDefault("100")
            int batchSize();

            /** Whether to keep starred entries when cleaning up old entries. */
            @WithDefault("true")
            boolean keepStarredEntries();

            default Instant statusesInstantThreshold() {
                return statusesMaxAge().toMillis() > 0
                        ? Instant.now().minus(statusesMaxAge())
                        : null;
            }
        }
    }

    interface Users {
        /** Whether to let users create accounts for themselves. */
        @WithDefault("false")
        boolean allowRegistrations();

        /** Minimum password length for user accounts. */
        @WithDefault("4")
        int minimumPasswordLength();

        /** Whether an email address is required when creating a user account. */
        @WithDefault("false")
        boolean emailAddressRequired();

        /** Whether to create a demo account the first time the app starts. */
        @WithDefault("false")
        boolean createDemoAccount();
    }

    interface Websocket {
        /**
         * Enable websocket connection so the server can notify web clients that there are new
         * entries for feeds.
         */
        @WithDefault("true")
        boolean enabled();

        /**
         * Interval at which the client will send a ping message on the websocket to keep the
         * connection alive.
         */
        @WithDefault("15m")
        Duration pingInterval();

        /**
         * If the websocket connection is disabled or the connection is lost, the client will reload
         * the feed tree at this interval.
         */
        @WithDefault("30s")
        Duration treeReloadInterval();
    }
}