/**
 * Wireguard peer schema definitions
 *
 * @since 1.0.0
 */

import type * as Brand from "effect/Brand";

import * as InternetSchemas from "effect-schemas/Internet";
import * as Array from "effect/Array";
import * as DateTime from "effect/DateTime";
import * as Duration from "effect/Duration";
import * as Effect from "effect/Effect";
import * as Function from "effect/Function";
import * as Number from "effect/Number";
import * as Option from "effect/Option";
import * as ParseResult from "effect/ParseResult";
import * as Schema from "effect/Schema";
import * as ini from "ini";
import * as WireguardInternetSchemas from "./InternetSchemas.ts";
import * as WireguardKey from "./WireguardKey.ts";

import * as internalWireguardPeer from "./internal/wireguardPeer.ts";

/**
 * A wireguard peer configuration.
 *
 * @since 1.0.0
 * @category Datatypes
 * @example
 *     ```ts
 *
 *     import * as Schema from "effect/Schema";
 *     import * as WireguardKey from "the-wireguard-effect/WireguardKey";
 *
 *     import { WireguardPeer } from "the-wireguard-effect/WireguardPeer";
 *
 *     const preshareKey = WireguardKey.generatePreshareKey();
 *     const { publicKey, privateKey: _privateKey } =
 *         WireguardKey.generateKeyPair();
 *
 *     const peerSchemaInstantiation = Schema.decode(WireguardPeer)({
 *         PublicKey: publicKey,
 *         PresharedKey: preshareKey,
 *         Endpoint: "192.168.0.1:51820",
 *         AllowedIPs: new Set(["192.168.0.0/24"]),
 *         PersistentKeepalive: 20,
 *     });
 *     ```;
 */
export class WireguardPeer extends internalWireguardPeer.WireguardPeerConfigVariantSchema.Class<WireguardPeer>(
    "WireguardPeer"
)({
    /**
     * The persistent keepalive interval in seconds, 0 disables it. The
     * difference between Option.none and Option.some(0) is important when
     * performing something like a config update operation on an interface
     * because Option.none will not include the keep alive setting in the update
     * request, so it will remain the same as it was before the update, whereas
     * Option.some(0) will disable the keep alive setting.
     */
    PersistentKeepalive: Schema.optionalWith(WireguardInternetSchemas.DurationFromSeconds, {
        as: "Option",
        nullable: true,
    }),

    /**
     * The collection of IPs/masks that will be accepted from this peer. If an
     * identical value already exists as part of a prior peer, the allowed IP
     * entry will be removed from that peer and added to this peer.
     */
    AllowedIPs: Schema.optionalWith(Schema.ReadonlySetFromSelf(InternetSchemas.CidrBlockFromString), {
        nullable: true,
        default: () => new Set([]),
    }),

    /**
     * The value for this key is either IP:port for IPv4 or [IP]:port for IPv6
     * or some.hostname.com:port for a hostname endpoint. The endpoint is
     * optional and, if not supplied, the remote peer must connect first (so
     * they should have the endpoint set to know where to connect to) and this
     * client will just send requests back to the remote peer's source IP and
     * port.
     */
    Endpoint: Schema.optionalWith(WireguardInternetSchemas.Endpoint, { nullable: true }),

    /** Lowercase hex-encoded public key of the new peer entry. */
    PublicKey: WireguardKey.WireguardKey,

    /**
     * The preshared key is optional and is a lowercase hex-encoded key. The
     * value may be an all zero string in the case of a set operation, in which
     * case it indicates that the preshared-key should be removed.
     */
    PresharedKey: Schema.optionalWith(WireguardKey.WireguardKey, { nullable: true, as: "Option" }),

    /** The number of received bytes. */
    rxBytes: internalWireguardPeer.WireguardPeerConfigVariantSchema.FieldOnly("uapi")(Schema.NumberFromString),

    /** The number of transmitted bytes. */
    txBytes: internalWireguardPeer.WireguardPeerConfigVariantSchema.FieldOnly("uapi")(Schema.NumberFromString),

    /**
     * The number of seconds since the most recent handshake, expressed relative
     * to the Unix epoch.
     */
    lastHandshake: internalWireguardPeer.WireguardPeerConfigVariantSchema.FieldOnly("uapi")(
        Function.pipe(
            Schema.NumberFromString,
            Schema.compose(
                Schema.transform(Schema.Number, Schema.Number, {
                    decode: Function.identity,
                    encode: Number.multiply(1000),
                })
            ),
            Schema.compose(Schema.DateTimeUtcFromNumber)
        )
    ),
}) {}

/**
 * A wireguard peer configuration encoded in INI format.
 *
 * @since 1.0.0
 * @category Transformations
 * @example
 *     ```ts
 *
 *     import * as Effect from "effect/Effect";
 *     import * as Function from "effect/Function";
 *     import * as Schema from "effect/Schema";
 *     import * as WireguardKey from "the-wireguard-effect/WireguardKey";
 *     import * as WireguardPeer from "the-wireguard-effect/WireguardPeer";
 *
 *     const preshareKey = WireguardKey.generatePreshareKey();
 *     const { publicKey, privateKey: _privateKey } =
 *         WireguardKey.generateKeyPair();
 *
 *     const peer = Schema.decode(WireguardPeer.WireguardPeer)({
 *         PublicKey: publicKey,
 *         PresharedKey: preshareKey,
 *         AllowedIPs: new Set(["192.168.0.0/24"]),
 *         Endpoint: "192.168.0.1:51820",
 *         PersistentKeepalive: 20,
 *     });
 *
 *     const iniPeer = Function.pipe(
 *         peer,
 *         Effect.flatMap(Schema.encode(WireguardPeer.WireguardPeer)),
 *         Effect.flatMap(Schema.decode(WireguardPeer.WireguardIniPeer))
 *     );
 *     ```;
 *
 * @see {@link WireguardPeer}
 */
export class WireguardIniPeer extends Schema.transformOrFail(WireguardPeer, Schema.String, {
    // The types really help make sure that everything in the output will be in the right format
    decode: (peer: WireguardPeer, _options, _ast) => {
        const publicKey: `PublicKey = ${string & Brand.Brand<"WireguardKey">}\n` =
            `PublicKey = ${peer.PublicKey}\n` as const;

        const presharedKey: "" | `PresharedKey = ${string & Brand.Brand<"WireguardKey">}\n` = Function.pipe(
            peer.PresharedKey,
            Option.map((key) => `PresharedKey = ${key}\n` as const),
            Option.getOrElse(() => "" as const)
        );

        const endpoint: "" | `Endpoint = ${string}:${Schema.Schema.Type<InternetSchemas.Port>}\n` = Function.pipe(
            peer.Endpoint,
            Option.fromNullable,
            Option.map((endpoint) => {
                const host = "address" in endpoint ? endpoint.address.ip : endpoint.host;
                return `Endpoint = ${host}:${endpoint.natPort}\n` as const;
            }),
            Option.getOrElse(() => "" as const)
        );

        const keepAlive: "" | `PersistentKeepalive = ${number}\n` = Function.pipe(
            peer.PersistentKeepalive,
            Option.map((keepalive) => `PersistentKeepalive = ${Duration.toSeconds(keepalive)}\n` as const),
            Option.getOrElse(() => "" as const)
        );

        const aps: `AllowedIPs = ${string}` = Function.pipe(
            peer.AllowedIPs,
            Array.fromIterable,
            Array.map((ap) => `${ap.address.ip}/${ap.mask}` as const),
            Array.map((ap) => `${ap}` as const),
            Array.join(", "),
            (x) => `AllowedIPs = ${x}` as const
        );

        return ParseResult.succeed(`[Peer]\n${publicKey}${presharedKey}${endpoint}${keepAlive}${aps}\n` as const);
    },
    // Encoding is trivial using the ini library
    encode: (iniPeer: string, _options, _ast) =>
        Function.pipe(
            iniPeer,
            ini.decode,
            (data) =>
                data as {
                    PublicKey: string;
                    PresharedKey?: string | undefined | null;
                    PersistentKeepalive?: string | undefined | null;
                    Endpoint?: Schema.Schema.Encoded<WireguardInternetSchemas.Endpoint> | undefined | null;
                    AllowedIPs?:
                        | Array<Schema.Schema.Encoded<InternetSchemas.CidrBlockFromString>>
                        | Schema.Schema.Encoded<InternetSchemas.CidrBlockFromString>
                        | undefined
                        | null;
                },
            ({ AllowedIPs, Endpoint, PersistentKeepalive, PresharedKey, PublicKey }) => ({
                PublicKey,
                PresharedKey,
                Endpoint,
                PersistentKeepalive: Function.pipe(
                    PersistentKeepalive,
                    Option.fromNullable,
                    Option.flatMap(Number.parse),
                    Option.getOrUndefined
                ),
                AllowedIPs: Function.pipe(
                    AllowedIPs,
                    Option.fromNullable,
                    Option.map((aps) => new Set(Array.isArray(aps) ? aps : [aps])),
                    Option.getOrUndefined
                ),
            }),
            Schema.decode(WireguardPeer, { onExcessProperty: "error" }),
            Effect.mapError(({ issue }) => issue)
        ),
}).annotations({
    identifier: "WireguardIniPeer",
    description: "A wireguard ini peer configuration",
}) {}

/**
 * @since 1.0.0
 * @category Schemas
 * @see https://www.wireguard.com/xplatform/
 */
export class WireguardUapiSetPeer extends Schema.transformOrFail(WireguardPeer, Schema.String, {
    encode: (uapiPeer: string, _options, ast) =>
        ParseResult.fail(new ParseResult.Forbidden(ast, uapiPeer, "Can not encode a UAPI set peer")),
    decode: (peer: WireguardPeer, _options, _ast) => {
        const publicKey: `public_key=${string}\n` = Function.pipe(
            peer.PublicKey,
            (key) => Buffer.from(key, "base64").toString("hex"),
            (hex) => `public_key=${hex}\n` as const
        );

        const presharedKeyHex: "" | `preshared_key=${string}\n` = Function.pipe(
            peer.PresharedKey,
            Option.map((key) => Buffer.from(key, "base64").toString("hex")),
            Option.map((hex) => `preshared_key=${hex}\n` as const),
            Option.getOrElse(() => "" as const)
        );

        const endpoint: "" | `endpoint=${string}:${Schema.Schema.Type<InternetSchemas.Port>}\n` = Function.pipe(
            peer.Endpoint,
            Option.fromNullable,
            Option.map((endpoint) => {
                const host = "address" in endpoint ? endpoint.address.ip : endpoint.host;
                return `endpoint=${host}:${endpoint.natPort}\n` as const;
            }),
            Option.getOrElse(() => "" as const)
        );

        const keepAlive: "" | `persistent_keepalive_interval=${number}\n` = Function.pipe(
            peer.PersistentKeepalive,
            Option.map(Duration.toSeconds),
            Option.map((seconds) => `persistent_keepalive_interval=${seconds}\n` as const),
            Option.getOrElse(() => "" as const)
        );

        const aps: Array<`allowed_ip=${string}/${number}`> = Function.pipe(
            peer.AllowedIPs,
            Array.fromIterable,
            Array.map((ap) => `${ap.address.ip}/${ap.mask}` as const),
            Array.map((ap) => `allowed_ip=${ap}` as const)
        );

        return ParseResult.succeed(`${publicKey}${presharedKeyHex}${endpoint}${keepAlive}${aps.join("\n")}\n`);
    },
}).annotations({
    identifier: "WireguardUapiSetPeer",
    description: "A wireguard uapi peer configuration",
}) {}

/**
 * @since 1.0.0
 * @category Schemas
 * @see https://www.wireguard.com/xplatform/
 */
export class WireguardUapiGetPeer extends Schema.transformOrFail(Schema.String, WireguardPeer["uapi"], {
    encode: (uapiPeer, _options, ast) =>
        ParseResult.fail(new ParseResult.Forbidden(ast, uapiPeer, "Can not decode a UAPI get peer")),
    decode: (uapiPeer: string) => {
        const data = ini.decode(uapiPeer);

        const {
            allowed_ip,
            endpoint,
            last_handshake_time_sec,
            persistent_keepalive_interval,
            preshared_key,
            public_key,
            rx_bytes,
            tx_bytes,
        } = data as {
            allowed_ip:
                | Schema.Schema.Encoded<InternetSchemas.CidrBlockFromString>
                | Array<Schema.Schema.Encoded<InternetSchemas.CidrBlockFromString>>
                | undefined
                | null;
            endpoint: Schema.Schema.Encoded<WireguardInternetSchemas.Endpoint> | undefined | null;
            last_handshake_time_sec: string;
            persistent_keepalive_interval: string | undefined | null;
            preshared_key: string | undefined | null;
            public_key: string;
            rx_bytes: string;
            tx_bytes: string;
        };

        const publicKey = Buffer.from(public_key, "hex").toString("base64");
        const presharedKey = Function.pipe(
            preshared_key,
            Option.fromNullable,
            Option.map((hex) => Buffer.from(hex, "hex").toString("base64")),
            Option.getOrUndefined
        );

        const allowedIps = Function.pipe(
            allowed_ip,
            Option.fromNullable,
            Option.map((aps) => new Set(Array.isArray(aps) ? aps : [aps])),
            Option.getOrUndefined
        );
        const keepAlive = Function.pipe(
            persistent_keepalive_interval,
            Option.fromNullable,
            Option.flatMap(Number.parse),
            Option.getOrUndefined
        );

        return ParseResult.succeed({
            rxBytes: rx_bytes,
            txBytes: tx_bytes,
            Endpoint: endpoint,
            PublicKey: publicKey,
            PresharedKey: presharedKey,
            lastHandshake: last_handshake_time_sec,
            AllowedIPs: allowedIps,
            PersistentKeepalive: keepAlive,
        });
    },
}).annotations({
    identifier: "WireguardUapiGetPeer",
    description: "A wireguard uapi peer configuration",
}) {}

/**
 * @since 1.0.0
 * @category Refinements
 */
export const hasBidirectionalTraffic = (
    wireguardPeer: Schema.Schema.Type<(typeof WireguardPeer)["uapi"]>
): Effect.Effect<boolean, never, never> => Effect.succeed(wireguardPeer.rxBytes > 0 && wireguardPeer.txBytes > 0);

/**
 * @since 1.0.0
 * @category Refinements
 */
export const hasHandshakedRecently = (
    wireguardPeer: Schema.Schema.Type<(typeof WireguardPeer)["uapi"]>
): Effect.Effect<boolean, never, never> =>
    Effect.Do.pipe(
        Effect.bind("now", () => DateTime.now),
        Effect.let("threshold", () => Duration.lessThanOrEqualTo(Duration.seconds(30))),
        Effect.map(({ now, threshold }) => threshold(DateTime.distanceDuration(wireguardPeer.lastHandshake, now)))
    );