const events = require("../lib/events.js");
const logger = require("../lib/logger.js");
const {hasFlag} = require("../lib/guildSettings.js");
const {parseHtmlEntities} = require("../lib/utils.js");

const FRIENDLY_USERAGENT =
  "HiddenPhox/fedimbed (https://gitlab.com/Cynosphere/HiddenPhox)";

const URLS_REGEX = /(?:\s|^)(https?:\/\/[^\s<]+[^<.,:;"'\]\s])/g;

const PATH_REGEX = {
  mastodon: /^\/@?(.+?)\/(statuses\/)?\d+\/?/,
  pleroma:
    /^\/objects\/[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}\/?/,
  pleroma2: /^\/notice\/[A-Za-z0-9]+\/?/,
  misskey: /^\/notes\/[a-z0-9]+\/?/,
  gotosocial: /^\/@(.+?)\/statuses\/[0-9A-Z]+\/?/,
};

const PLATFORM_COLORS = {
  mastodon: 0x2791da,
  pleroma: 0xfba457,
  akkoma: 0x593196,
  misskey: 0x99c203,
  calckey: 0x31748f,
  gotosocial: 0xff853e,
};

const domainCache = new Map();
async function resolvePlatform(url) {
  const urlObj = new URL(url);
  if (domainCache.has(urlObj.hostname)) return domainCache.get(urlObj.hostname);

  const probe = await fetch(urlObj.origin + "/.well-known/nodeinfo", {
    headers: {"User-Agent": FRIENDLY_USERAGENT},
  }).then((res) => res.json());

  if (!probe?.links) {
    logger.error("fedimbed", `No nodeinfo for "${urlObj.hostname}"???`);
    domainCache.set(urlObj.hostname, null);
    return null;
  }

  const nodeinfo = await fetch(probe.links[probe.links.length - 1].href, {
    headers: {"User-Agent": FRIENDLY_USERAGENT},
  }).then((res) => res.json());

  if (!nodeinfo?.software?.name) {
    logger.error(
      "fedimbed",
      `Got nodeinfo for "${urlObj.hostname}", but missing software name.`
    );
    domainCache.set(urlObj.hostname, null);
    return null;
  }

  domainCache.set(urlObj.hostname, nodeinfo.software.name);
  return nodeinfo.software.name;
}

async function processUrl(msg, url) {
  const urlObj = new URL(url);
  const platform = await resolvePlatform(url);
  const color = PLATFORM_COLORS[platform];
  const platformName = platform
    .replace("gotosocial", "GoToSocial")
    .replace(/^(.)/, (_, c) => c.toUpperCase());

  const attachments = [];
  let content, cw, author;

  // Fetch post
  const postData = await fetch(url, {
    headers: {
      "User-Agent": FRIENDLY_USERAGENT,
      Accept: "application/activity+json",
      "Content-Type": "application/activity+json",
    },
  })
    .then((res) => res.json())
    .catch((err) => {
      logger.error("fedimbed", `Failed to fetch "${url}" as AS2: ${err}`);
    });

  if (postData.error) {
    logger.error("fedimbed", `Received error for "${url}": ${postData.error}`);
    return;
  }

  if (!postData) {
    // We failed to get post.
    // If we're fetching from Pleroma, assume it was due to AMF and use MastoAPI
    if (PATH_REGEX.pleroma.test(urlObj.pathname)) {
      url = await fetch(url, {
        method: "HEAD",
        headers: {
          "User-Agent": FRIENDLY_USERAGENT,
        },
        redirect: "manual",
      }).then((res) => res.headers.get("location"));
    }

    if (PATH_REGEX.pleroma2.test(urlObj.pathname)) {
      const postData2 = await fetch(url.replace("notice", "api/v1/statuses"), {
        headers: {
          "User-Agent": FRIENDLY_USERAGENT,
        },
      })
        .then((res) => res.json())
        .catch((err) => {
          logger.error(
            "fedimbed",
            `Failed to fetch "${url}" as MastoAPI: ${err}`
          );
        });

      if (!postData2) {
        logger.warn(
          "fedimbed",
          `Bailing trying to re-embed "${url}": Failed to get post from both AS2 and MastoAPI.`
        );
      } else {
        cw = postData2.spoiler_warning;
        content =
          postData2.akkoma?.source?.content ??
          postData2.pleroma?.content?.["text/plain"] ??
          postData2.content;
        author = {
          name: postData2.account.display_name,
          handle: postData2.account.fqn,
          url: postData2.account.url,
          avatar: postData2.account.avatar,
        };
        for (const attachment of postData.media_attachments) {
          attachments.push({
            url: attachment.url,
            desc: attachment.description,
          });
        }
      }
    }
  } else {
    content = postData.content;
    cw = postData.summary;
    for (const attachment of postData.attachment) {
      attachments.push({
        url: attachment.url,
        desc: attachment.name,
      });
    }

    // Author data is not sent with the post with AS2
    const authorData = await fetch(postData.actor, {
      headers: {
        "User-Agent": FRIENDLY_USERAGENT,
        Accept: "application/activity+json",
        "Content-Type": "application/activity+json",
      },
    })
      .then((res) => res.json())
      .catch((err) => {
        logger.error("fedimbed", `Failed to get author for "${url}": ${err}`);
      });

    if (authorData) {
      author = {
        name: authorData.name,
        handle: `${authorData.preferredUsername}@${urlObj.hostname}`,
        url: authorData.url,
        avatar: authorData.icon.url,
      };
    }
  }

  // We could just continue without author but it'd look ugly and be confusing.
  if (!author) {
    logger.warn(
      "fedimbed"`Bailing trying to re-embed "${url}": Failed to get author.`
    );
    return;
  }

  // Start constructing embed
  content = content ?? "";
  cw = cw ?? "";

  // TODO: convert certain HTML tags back to markdown
  content = content.replace(/(<([^>]+)>)/gi,"");
  content = parseHtmlEntities(content);

  cw = cw.replace(/(<([^>]+)>)/gi,"");
  cw = parseHtmlEntities(cw);

  let desc = "";
  let MAX_LENGTH = 3999;
  if (cw != "") {
    desc += "\u26a0 " + cw + "\n\n||" + content + "||";
    MAX_LENGTH -= 8 - cw.length;
  } else {
    desc = content;
  }

  if (desc.length > MAX_LENGTH) {
    if (desc.endsWith("||")) {
      desc = desc.substring(0, MAX_LENGTH - 2);
      desc += "\u2026||";
    } else {
      desc = desc.substring(0, MAX_LENGTH) + "\u2026";
    }
  }

  const baseEmbed = {
    color,
    url,
    description: desc,
    title: `${author.name} (${author.handle})`,
    author: {
      name: platformName,
    },
    thumbnail: {
      url: author.url,
    },
    fields: [],
  };
  if (attachments.length > 0) {
    if (attachments.length > 1) {
      baseEmbed.fields.push({
        name: "Images",
        value: attachments
          .map((attachment, index) => `[Image ${index + 1}](${attachment.url})`)
          .join(" | "),
      });
    } else {
      baseEmbed.fields.push({
        name: "Image",
        value: `[Click for image](${attachments[0].url})`,
      });
    }
  }

  const embeds = [];

  for (const attachment of attachments) {
    const embed = Object.assign({}, baseEmbed);
    embed.image = {
      url: attachment.url,
    };
    embeds.push(embed);
  }

  msg.channel.createMessage({
    embeds,
    allowedMentions: {
      repliedUser: false,
    },
    messageReference: {
      messageID: msg.id,
    },
  });
}

events.add("messageCreate", "fedimbed", async function (msg) {
  if (!msg.guildID) return;
  if (!(await hasFlag(msg.guildID, "fedimbed"))) return;
  if (!msg.content || msg.content == "") return;

  if (URLS_REGEX.test(msg.content)) {
    const urls = msg.content.match(URLS_REGEX);
    for (const url of urls) {
      for (const service of Object.keys(PATH_REGEX)) {
        const regex = PATH_REGEX[service];
        const urlObj = new URL(url);
        if (regex.test(urlObj.pathname)) {
          logger.verbose(
            "fedimbed",
            `Hit "${service}" for "${url}", processing now.`
          );
          await processUrl(msg, url).catch((err) => {
            logger.error("fedimbed", `Error processing "${url}": ${err}`);
          });
          break;
        }
      }
    }
  }
});