/// <reference path="../imports/imports_shared.d.ts" />


window["require_setup"](module);

import * as dns_handler from "dns";

namespace _dns {
    type Lookup<R> = (hostname: string, callback: (err: NodeJS.ErrnoException, result: R) => void) => void;
    type AsyncLookup<R> = (hostname: string, timeout: number) => Promise<R>;
    function make_async<R>(fun: Lookup<R>) : AsyncLookup<R> {
        return (hostname, timeout) => {
            return new Promise<R>((resolve, reject) => {
                const timeout_id = setTimeout(() => {
                    reject("timeout");
                }, timeout);
                fun(hostname, (err, result) => {
                    clearTimeout(timeout_id);
                    if(err) {
                        if(err.errno as any == "ENOTFOUND" || err.errno as any == "ENODATA") {
                            resolve(null);
                            return;
                        }

                        reject(err);
                    } else
                        resolve(result);
                })
            });
        };
    }

    const async_resolve_srv = make_async(dns_handler.resolveSrv);
    const async_resolve_cname = make_async(dns_handler.resolveCname);
    const async_resolve_a = make_async(dns_handler.resolve4);
    const async_resolve_aaaa = make_async(dns_handler.resolve6);
    const async_resolve_any = make_async(dns_handler.resolveAny);

    export interface AddressTarget {
        target_ip: string;
        target_port?: number;
    }
    export interface ResolveOptions extends dns.ResolveOptions {
        log?: (message: string, ...args: any[]) => void;
        override_port?: number;
    }

    export function supported() { return true; }
    export async function resolve_address(address: string, _options?: ResolveOptions) : Promise<AddressTarget> {
        if(address === "localhost") {
            return {
                target_ip: "localhost"
            };
        }

        const options: ResolveOptions = {};
        Object.assign(options, dns.default_options);
        Object.assign(options, _options || {});

        if(options.max_depth <= 0)
            throw "max depth exceeded";

        if(typeof(options.log) !== "function")
            options.log = (message, ...args) => console.debug("[DNS] " + message, ...args);

        const mod_options: ResolveOptions = {};
        Object.assign(mod_options, options);
        mod_options.max_depth = mod_options.max_depth - 1;
        mod_options.allow_srv = false;
        mod_options.log = (message, ...args) => options.log("  " + message, ...args);

        options.log("Resolving %s", address);

        let response: AddressTarget;
        if(typeof(options.allow_aaaa) !== "boolean" || options.allow_aaaa) {
            const aaaa_response: string[] | undefined | null = await async_resolve_aaaa(address, options.timeout).catch(error => {
                options.log("AAAA record resolved unsuccessfully (%o)", error);
                return Promise.resolve(undefined);
            }) as any;


            if(typeof(aaaa_response) !== "undefined") {
                if(!aaaa_response || aaaa_response.length == 0)
                    options.log("No AAAA records found");
                else {
                    options.log("Resolved AAAA records: %o. Returning: %s", aaaa_response, aaaa_response[0]);
                    response = {
                        target_ip: aaaa_response[0],
                        target_port: options.override_port
                    };
                }
            }
        }
        if(!response && (typeof(options.allow_a) !== "boolean" || options.allow_a)) {
            const a_response: string[] | undefined | null = await async_resolve_a(address, options.timeout).catch(error => {
                options.log("A record resolved unsuccessfully (%o)", error);
                return Promise.resolve(undefined);
            }) as any;

            if(typeof(a_response) !== "undefined") {
                if(!a_response || a_response.length == 0)
                    options.log("No A records found");
                else {
                    options.log("Resolved A records: %o. Returning: %s", a_response, a_response[0]);
                    response = {
                        target_ip: a_response[0],
                        target_port: options.override_port
                    };
                }
            }
        }

        if(!response && (typeof(options.allow_any) !== "boolean" || options.allow_any)) {
            const any_response: dns_handler.AnyRecord[] = await async_resolve_any(address, options.timeout).catch(error => {
                options.log("ANY record resolved unsuccessfully (%o)", error);
                return Promise.resolve(undefined);
            });


            if(typeof(any_response) !== "undefined") {
                if(!any_response || any_response.length == 0)
                    options.log("No ANY records found");
                else {
                    options.log("Resolved ANY records: %o.", any_response);
                    for(const record of any_response) {
                        if(record.type === "A") {
                            const a_record = record as dns_handler.AnyARecord;
                            options.log("Returning A record from ANY query: %s", a_record.address);
                            return {
                                target_ip: a_record.address,
                                target_port: options.override_port
                            };
                        } else if(record.type === "AAAA") {
                            const aaaa_record = record as dns_handler.AnyAaaaRecord;
                            options.log("Returning AAAA record from ANY query: %s", aaaa_record.address);
                            return {
                                target_ip: aaaa_record.address,
                                target_port: options.override_port
                            };
                        }
                    }
                }
            }
        }

        if(typeof(options.allow_srv) !== "boolean" || options.allow_srv) {
            const response: dns_handler.SrvRecord[] = await async_resolve_srv("_ts3._udp." + address, options.timeout).catch(error => {
                options.log("SRV resolve unsuccessfully (%o)", error);
                return Promise.resolve(undefined);
            });

            if(typeof(response) !== "undefined") {
                if(!response || response.length == 0)
                    options.log("No SRV records found");
                else {
                    const sorted = response.sort((a, b) => b.weight - a.weight);
                    const original_port = mod_options.override_port;
                    options.log("Resolved SRV records: %o", sorted);
                    for(const entry of sorted) {
                        options.log("Resolving SRV record: %o", entry);
                        mod_options.override_port = entry.port || mod_options.override_port;
                        const resp = await resolve_address(entry.name, mod_options).catch(error => {
                            options.log("SRV entry resolved unsuccessfully (%o)", error);
                            return Promise.resolve(undefined);
                        });
                        if(resp) {
                            options.log("SRV entry resolved to %o. Found result", resp);
                            return resp;
                        } else {
                            options.log("No response for SRV record");
                        }
                    }
                    mod_options.override_port = original_port;
                }
            }
        }

        /* resolve CNAME in the last step, else may the A records will be empty! */
        if(typeof(options.allow_cname) !== "boolean" || options.allow_cname) {
            const cname_response: string[] = await async_resolve_cname(address, options.timeout).catch(error => {
                options.log("CName resolved unsuccessfully (%o)", error);
                return Promise.resolve(undefined);
            });

            if(typeof(cname_response) !== "undefined") {
                if(!cname_response || cname_response.length == 0)
                    options.log("No CNAME records found");
                else {
                    options.log("Resolved %d CNAME records", cname_response.length);
                    for(const entry of cname_response) {
                        options.log("Resolving CNAME record: %o", entry);
                        const resp = await resolve_address(entry, mod_options).catch(error => {
                            options.log("Failed to resolve resolved CName (%o)", error);
                            return Promise.resolve(undefined);
                        });
                        if(resp) {
                            options.log("CName entry resolved to %o. Found result", resp);
                            return resp;
                        } else {
                            options.log("No response for CName record");
                        }
                    }
                    response = undefined; /* overridden by a CNAME */
                }
            }
        }

        /*
        const lookup_result = await new Promise((resolve, reject) => {
            const timeout = setTimeout(() => {
                reject("timeout");
            }, options.timeout);
            dns_handler.lookup(address, {
                hints: dns_handler.ADDRCONFIG | dns_handler.V4MAPPED,
                all: true,
                family: 0
            }, (error, result, family) => {
                clearTimeout(timeout);
                console.log(result);
                if(error) {
                    if(error.errno as any == "ENOTFOUND" || error.errno as any == "ENODATA") {
                        resolve(null);
                        return;
                    }

                    reject(error);
                } else
                    resolve(result);
            });
        }).catch(error => {
            options.log("General lookup failed: %o", error);
            return Promise.resolve(undefined);
        });
        console.log(lookup_result);
        */
        if(response)
            return response;
        options.log("No records found, no result.");
        return undefined;
    }

    dns_handler.setServers(["8.8.8.8", "8.8.8.4", "1.1.1.1"]);
}

Object.assign(window["dns"] || (window["dns"] = {}), _dns);