import {
  Client,
  EmbedOptions,
  Emoji,
  Guild,
  GuildAuditLogEntry,
  Member,
  TextableChannel,
  TextChannel,
  User,
} from "eris";
import url from "url";
import tlds from "tlds";
import emojiRegex from "emoji-regex/text";
import * as t from "io-ts";

import fs from "fs";
const fsp = fs.promises;

import https from "https";
import tmp from "tmp";
import { logger } from "knub";

const delayStringMultipliers = {
  w: 1000 * 60 * 60 * 24 * 7,
  d: 1000 * 60 * 60 * 24,
  h: 1000 * 60 * 60,
  m: 1000 * 60,
  s: 1000,
};

export function tNullable(type: t.Mixed) {
  return t.union([type, t.undefined, t.null]);
}

/**
 * Turns a "delay string" such as "1h30m" to milliseconds
 */
export function convertDelayStringToMS(str, defaultUnit = "m"): number {
  const regex = /^([0-9]+)\s*([wdhms])?[a-z]*\s*/;
  let match;
  let ms = 0;

  str = str.trim();

  // tslint:disable-next-line
  while (str !== "" && (match = str.match(regex)) !== null) {
    ms += match[1] * ((match[2] && delayStringMultipliers[match[2]]) || delayStringMultipliers[defaultUnit]);
    str = str.slice(match[0].length);
  }

  // Invalid delay string
  if (str !== "") {
    return null;
  }

  return ms;
}

export function successMessage(str) {
  return `👌 ${str}`;
}

export function errorMessage(str) {
  return `⚠ ${str}`;
}

export function get(obj, path, def?): any {
  let cursor = obj;
  const pathParts = path.split(".");
  for (const part of pathParts) {
    cursor = cursor[part];
    if (cursor === undefined) return def;
    if (cursor == null) return null;
  }
  return cursor;
}

export function has(obj, path): boolean {
  return get(obj, path) !== undefined;
}

export function stripObjectToScalars(obj, includedNested: string[] = []) {
  const result = Array.isArray(obj) ? [] : {};

  for (const key in obj) {
    if (
      obj[key] == null ||
      typeof obj[key] === "string" ||
      typeof obj[key] === "number" ||
      typeof obj[key] === "boolean"
    ) {
      result[key] = obj[key];
    } else if (typeof obj[key] === "object") {
      const prefix = `${key}.`;
      const nestedNested = includedNested
        .filter(p => p === key || p.startsWith(prefix))
        .map(p => (p === key ? p : p.slice(prefix.length)));

      if (nestedNested.length) {
        result[key] = stripObjectToScalars(obj[key], nestedNested);
      }
    }
  }

  return result;
}

export const snowflakeRegex = /[1-9][0-9]{5,19}/;

const isSnowflakeRegex = new RegExp(`^${snowflakeRegex.source}$`);
export function isSnowflake(v: string): boolean {
  return isSnowflakeRegex.test(v);
}

export function sleep(ms: number): Promise<void> {
  return new Promise(resolve => {
    setTimeout(resolve, ms);
  });
}

/**
 * Attempts to find a relevant audit log entry for the given user and action
 */
export async function findRelevantAuditLogEntry(
  guild: Guild,
  actionType: number,
  userId: string,
  attempts: number = 3,
  attemptDelay: number = 3000,
): Promise<GuildAuditLogEntry> {
  const auditLogEntries = await guild.getAuditLogs(5, null, actionType);

  auditLogEntries.entries.sort((a, b) => {
    if (a.createdAt > b.createdAt) return -1;
    if (a.createdAt > b.createdAt) return 1;
    return 0;
  });

  const cutoffTS = Date.now() - 1000 * 60 * 2;

  const relevantEntry = auditLogEntries.entries.find(entry => {
    return entry.targetID === userId && entry.createdAt >= cutoffTS;
  });

  if (relevantEntry) {
    return relevantEntry;
  } else if (attempts > 0) {
    await sleep(attemptDelay);
    return findRelevantAuditLogEntry(guild, actionType, userId, attempts - 1, attemptDelay);
  } else {
    return null;
  }
}

const urlRegex = /(\S+\.\S+)/g;
const protocolRegex = /^[a-z]+:\/\//;

export function getUrlsInString(str: string): url.URL[] {
  const matches = str.match(urlRegex) || [];
  return matches.reduce((urls, match) => {
    if (!protocolRegex.test(match)) {
      match = `https://${match}`;
    }

    let matchUrl: url.URL;
    try {
      matchUrl = new url.URL(match);
    } catch (e) {
      return urls;
    }

    const hostnameParts = matchUrl.hostname.split(".");
    const tld = hostnameParts[hostnameParts.length - 1];
    if (tlds.includes(tld)) {
      urls.push(matchUrl);
    }

    return urls;
  }, []);
}

export function getInviteCodesInString(str: string): string[] {
  const inviteCodeRegex = /(?:discord.gg|discordapp.com\/invite)\/([a-z0-9]+)/gi;
  const inviteCodes = [];
  let match;

  // tslint:disable-next-line
  while ((match = inviteCodeRegex.exec(str)) !== null) {
    inviteCodes.push(match[1]);
  }

  return inviteCodes;
}

export const unicodeEmojiRegex = emojiRegex();
export const customEmojiRegex = /<a?:(.*?):(\d+)>/;

const matchAllEmojiRegex = new RegExp(`(${unicodeEmojiRegex.source})|(${customEmojiRegex.source})`, "g");

export function getEmojiInString(str: string): string[] {
  return str.match(matchAllEmojiRegex) || [];
}

export function isEmoji(str: string): boolean {
  return str.match(`^(${unicodeEmojiRegex.source})|(${customEmojiRegex.source})$`) !== null;
}

export function isUnicodeEmoji(str: string): boolean {
  return str.match(`^${unicodeEmojiRegex.source}$`) !== null;
}

export function trimLines(str: string) {
  return str
    .trim()
    .split("\n")
    .map(l => l.trim())
    .join("\n")
    .trim();
}

export function asSingleLine(str: string) {
  return trimLines(str).replace(/\n/g, " ");
}

export const emptyEmbedValue = "\u200b";
export const embedPadding = "\n" + emptyEmbedValue;

export const userMentionRegex = /<@!?([0-9]+)>/g;
export const roleMentionRegex = /<@&([0-9]+)>/g;
export const channelMentionRegex = /<#([0-9]+)>/g;

export function getUserMentions(str: string) {
  const regex = new RegExp(userMentionRegex.source, "g");
  const userIds = [];
  let match;

  // tslint:disable-next-line
  while ((match = regex.exec(str)) !== null) {
    userIds.push(match[1]);
  }

  return userIds;
}

export function getRoleMentions(str: string) {
  const regex = new RegExp(roleMentionRegex.source, "g");
  const roleIds = [];
  let match;

  // tslint:disable-next-line
  while ((match = regex.exec(str)) !== null) {
    roleIds.push(match[1]);
  }

  return roleIds;
}

/**
 * Disables link previews in the given string by wrapping links in < >
 */
export function disableLinkPreviews(str: string): string {
  return str.replace(/(?<!<)(https?:\/\/\S+)/gi, "<$1>");
}

export function deactivateMentions(content: string): string {
  return content.replace(/@/g, "@\u200b");
}

export function disableCodeBlocks(content: string): string {
  return content.replace(/`/g, "`\u200b");
}

export function useMediaUrls(content: string): string {
  return content.replace(/cdn\.discordapp\.com/g, "media.discordapp.net");
}

export function chunkArray<T>(arr: T[], chunkSize): T[][] {
  const chunks: T[][] = [];
  let currentChunk = [];

  for (let i = 0; i < arr.length; i++) {
    currentChunk.push(arr[i]);
    if ((i !== 0 && i % chunkSize === 0) || i === arr.length - 1) {
      chunks.push(currentChunk);
      currentChunk = [];
    }
  }

  return chunks;
}

export function chunkLines(str: string, maxChunkLength = 2000): string[] {
  if (str.length < maxChunkLength) {
    return [str];
  }

  const chunks = [];

  while (str.length) {
    if (str.length <= maxChunkLength) {
      chunks.push(str);
      break;
    }

    const slice = str.slice(0, maxChunkLength);

    const lastLineBreakIndex = slice.lastIndexOf("\n");
    if (lastLineBreakIndex === -1) {
      chunks.push(str.slice(0, maxChunkLength));
      str = str.slice(maxChunkLength);
    } else {
      chunks.push(str.slice(0, lastLineBreakIndex));
      str = str.slice(lastLineBreakIndex + 1);
    }
  }

  return chunks;
}

/**
 * Chunks a long message to multiple smaller messages, retaining leading and trailing line breaks, open code blocks, etc.
 */
export function chunkMessageLines(str: string): string[] {
  const chunks = chunkLines(str, 1990); // We don't split at exactly 2000 to be able to do the stuff below
  let openCodeBlock = false;

  return chunks.map(chunk => {
    // If the chunk starts with a newline, add an invisible unicode char so Discord doesn't strip it away
    if (chunk[0] === "\n") chunk = "\u200b" + chunk;
    // If the chunk ends with a newline, add an invisible unicode char so Discord doesn't strip it away
    if (chunk[chunk.length - 1] === "\n") chunk = chunk + "\u200b";
    // If the previous chunk had an open code block, open it here again
    if (openCodeBlock) {
      openCodeBlock = false;
      if (chunk.startsWith("```")) {
        // Edge case: chunk starts with a code block delimiter, e.g. the previous chunk and this one were split right before the end of a code block
        // Fix: just strip the code block delimiter away from here, we don't need it anymore
        chunk = chunk.slice(3);
      } else {
        chunk = "```" + chunk;
      }
    }
    // If the chunk has an open code block, close it and open it again in the next chunk
    const codeBlockDelimiters = chunk.match(/```/g);
    if (codeBlockDelimiters && codeBlockDelimiters.length % 2 !== 0) {
      chunk += "```";
      openCodeBlock = true;
    }

    return chunk;
  });
}

export async function createChunkedMessage(channel: TextableChannel, messageText: string) {
  const chunks = chunkMessageLines(messageText);
  for (const chunk of chunks) {
    await channel.createMessage(chunk);
  }
}

/**
 * Downloads the file from the given URL to a temporary file, with retry support
 */
export function downloadFile(attachmentUrl: string, retries = 3): Promise<{ path: string; deleteFn: () => void }> {
  return new Promise(resolve => {
    tmp.file((err, path, fd, deleteFn) => {
      if (err) throw err;

      const writeStream = fs.createWriteStream(path);

      https
        .get(attachmentUrl, res => {
          res.pipe(writeStream);
          writeStream.on("finish", () => {
            writeStream.end();
            resolve({
              path,
              deleteFn,
            });
          });
        })
        .on("error", httpsErr => {
          fsp.unlink(path);

          if (retries === 0) {
            throw httpsErr;
          } else {
            console.warn("File download failed, retrying. Error given:", httpsErr.message);
            resolve(downloadFile(attachmentUrl, retries - 1));
          }
        });
    });
  });
}

type ItemWithRanking<T> = [T, number];
export function simpleClosestStringMatch<T>(searchStr, haystack: T[], getter = null): T {
  const normalizedSearchStr = searchStr.toLowerCase();

  // See if any haystack item contains a part of the search string
  const itemsWithRankings: Array<ItemWithRanking<T>> = haystack.map(item => {
    const itemStr: string = getter ? getter(item) : item;
    const normalizedItemStr = itemStr.toLowerCase();

    let i = 0;
    do {
      if (!normalizedItemStr.includes(normalizedSearchStr.slice(0, i + 1))) break;
      i++;
    } while (i < normalizedSearchStr.length);

    if (i > 0 && normalizedItemStr.startsWith(normalizedSearchStr.slice(0, i))) {
      // Slightly prioritize items that *start* with the search string
      i += 0.5;
    }

    return [item, i] as ItemWithRanking<T>;
  });

  // Sort by best match
  itemsWithRankings.sort((a, b) => {
    return a[1] > b[1] ? -1 : 1;
  });

  if (itemsWithRankings[0][1] === 0) {
    return null;
  }

  return itemsWithRankings[0][0];
}

type sorterDirection = "ASC" | "DESC";
type sorterGetterFn = (any) => any;
type sorterGetterFnWithDirection = [sorterGetterFn, sorterDirection];
type sorterGetterResolvable = string | sorterGetterFn;
type sorterGetterResolvableWithDirection = [sorterGetterResolvable, sorterDirection];
type sorterFn = (a: any, b: any) => number;

function resolveGetter(getter: sorterGetterResolvable): sorterGetterFn {
  if (typeof getter === "string") {
    return obj => obj[getter];
  }

  return getter;
}

export function multiSorter(getters: Array<sorterGetterResolvable | sorterGetterResolvableWithDirection>): sorterFn {
  const resolvedGetters: sorterGetterFnWithDirection[] = getters.map(getter => {
    if (Array.isArray(getter)) {
      return [resolveGetter(getter[0]), getter[1]] as sorterGetterFnWithDirection;
    } else {
      return [resolveGetter(getter), "ASC"] as sorterGetterFnWithDirection;
    }
  });

  return (a, b) => {
    for (const getter of resolvedGetters) {
      const aVal = getter[0](a);
      const bVal = getter[0](b);
      if (aVal > bVal) return getter[1] === "ASC" ? 1 : -1;
      if (aVal < bVal) return getter[1] === "ASC" ? -1 : 1;
    }

    return 0;
  };
}

export function sorter(getter: sorterGetterResolvable, direction: sorterDirection = "ASC"): sorterFn {
  return multiSorter([[getter, direction]]);
}

export function noop() {
  // IT'S LITERALLY NOTHING
}

export const DBDateFormat = "YYYY-MM-DD HH:mm:ss";

export type CustomEmoji = {
  id: string;
} & Emoji;

export interface INotifyUserConfig {
  useDM?: boolean;
  useChannel?: boolean;
  channelId?: string;
}

export enum NotifyUserStatus {
  Ignored = 1,
  Failed,
  DirectMessaged,
  ChannelMessaged,
}

export interface INotifyUserResult {
  status: NotifyUserStatus;
  text?: string;
}

export async function notifyUser(
  bot: Client,
  guild: Guild,
  user: User,
  body: string,
  config: INotifyUserConfig,
): Promise<INotifyUserResult> {
  if (!config.useDM && !config.useChannel) {
    return { status: NotifyUserStatus.Ignored };
  }

  if (config.useDM) {
    try {
      const dmChannel = await bot.getDMChannel(user.id);
      await dmChannel.createMessage(body);
      logger.info(`Notified ${user.id} via DM: ${body}`);
      return {
        status: NotifyUserStatus.DirectMessaged,
        text: "user notified with a direct message",
      };
    } catch (e) {} // tslint:disable-line
  }

  if (config.useChannel && config.channelId) {
    try {
      const channel = guild.channels.get(config.channelId);
      if (channel instanceof TextChannel) {
        await channel.createMessage(`<@!${user.id}> ${body}`);
        return {
          status: NotifyUserStatus.ChannelMessaged,
          text: `user notified in <#${channel.id}>`,
        };
      }
    } catch (e) {} // tslint:disable-line
  }

  return {
    status: NotifyUserStatus.Failed,
    text: "failed to message user",
  };
}

export function ucfirst(str) {
  if (typeof str !== "string" || str === "") return str;
  return str[0].toUpperCase() + str.slice(1);
}

export class UnknownUser {
  public id: string = null;
  public username = "Unknown";
  public discriminator = "0000";

  constructor(props = {}) {
    for (const key in props) {
      this[key] = props[key];
    }
  }
}

const unknownUsers = new Set();
const unknownMembers = new Set();

export async function resolveUser(bot: Client, value: string): Promise<User | UnknownUser> {
  if (value == null || typeof value !== "string") {
    return new UnknownUser();
  }

  let userId;

  // A user mention?
  const mentionMatch = value.match(/^<@!?(\d+)>$/);
  if (mentionMatch) {
    userId = mentionMatch[1];
  }

  // A non-mention, full username?
  if (!userId) {
    const usernameMatch = value.match(/^@?([^#]+)#(\d{4})$/);
    if (usernameMatch) {
      const user = bot.users.find(u => u.username === usernameMatch[1] && u.discriminator === usernameMatch[2]);
      if (user) userId = user.id;
    }
  }

  // Just a user ID?
  if (!userId) {
    const idMatch = value.match(/^\d+$/);
    if (!idMatch) {
      return null;
    }

    userId = value;
  }

  const cachedUser = bot.users.find(u => u.id === userId);
  if (cachedUser) return cachedUser;

  // We only fetch the user from the API if we haven't tried it before:
  // - If the user was found, the bot has them in its cache
  // - If the user was not found, they'll be in unknownUsers
  if (!unknownUsers.has(userId)) {
    try {
      const freshUser = await bot.getRESTUser(userId);
      bot.users.add(freshUser, bot);
      return freshUser;
    } catch (e) {} // tslint:disable-line

    unknownUsers.add(userId);
  }

  return new UnknownUser({ id: userId });
}

export async function resolveMember(bot: Client, guild: Guild, value: string): Promise<Member> {
  // Start by resolving the user
  const user = await resolveUser(bot, value);
  if (!user || user instanceof UnknownUser) return null;

  // See if we have the member cached...
  let member = guild.members.get(user.id);

  // We only fetch the member from the API if we haven't tried it before:
  // - If the member was found, the bot has them in the guild's member cache
  // - If the member was not found, they'll be in unknownMembers
  const unknownKey = `${guild.id}-${user.id}`;
  if (!unknownMembers.has(unknownKey)) {
    // If not, fetch it from the API
    if (!member) {
      try {
        logger.debug(`Fetching unknown member (${user.id} in ${guild.name} (${guild.id})) from the API`);

        member = await bot.getRESTGuildMember(guild.id, user.id);
        member.id = user.id;
        member.guild = guild;
      } catch (e) {} // tslint:disable-line
    }

    if (!member) unknownMembers.add(unknownKey);
  }

  return member;
}

export const MS = 1;
export const SECONDS = 1000 * MS;
export const MINUTES = 60 * SECONDS;
export const HOURS = 60 * MINUTES;
export const DAYS = 24 * HOURS;

export type StrictMessageContent = { content?: string; tts?: boolean; disableEveryone?: boolean; embed?: EmbedOptions };