import { dbGlobal } from "drizzle-pkg/lib/db";
import { rssFeeds, rssItems } from "drizzle-pkg/lib/schema/rss";
import { users } from "drizzle-pkg/lib/schema/auth";
import { and, desc, eq } from "drizzle-orm";
import { XMLParser } from "fast-xml-parser";
import { assertSafeRssUrl } from "#server/utils/rss-url";
import { RssUrlUnsafeError } from "#server/utils/rss-url";
import { nextIntegerId } from "#server/utils/sqlite-id";
import { visibilityShareToken } from "#server/utils/share-token";

const DEFAULT_POLL_MINUTES = Number(process.env.RSS_SYNC_INTERVAL_MINUTES ?? 60);
const FETCH_TIMEOUT_MS = Number(process.env.RSS_FETCH_TIMEOUT_MS ?? 15_000);
const MAX_BODY_BYTES = Number(process.env.RSS_MAX_RESPONSE_BYTES ?? 2_000_000);

export async function listFeedsForUser(userId: number) {
  return dbGlobal.select().from(rssFeeds).where(eq(rssFeeds.userId, userId)).orderBy(desc(rssFeeds.id));
}

export async function addFeed(userId: number, feedUrl: string) {
  const url = assertSafeRssUrl(feedUrl.trim());
  const [dup] = await dbGlobal
    .select({ id: rssFeeds.id })
    .from(rssFeeds)
    .where(and(eq(rssFeeds.userId, userId), eq(rssFeeds.feedUrl, url)))
    .limit(1);
  if (dup) {
    throw createError({ statusCode: 409, statusMessage: "该订阅地址已存在" });
  }
  const id = await nextIntegerId(rssFeeds, rssFeeds.id);
  await dbGlobal.insert(rssFeeds).values({
    id,
    userId,
    feedUrl: url,
  });
  const [row] = await dbGlobal.select().from(rssFeeds).where(eq(rssFeeds.id, id)).limit(1);
  return row;
}

export async function deleteFeed(userId: number, feedId: number) {
  const [row] = await dbGlobal
    .select({ id: rssFeeds.id })
    .from(rssFeeds)
    .where(and(eq(rssFeeds.id, feedId), eq(rssFeeds.userId, userId)))
    .limit(1);
  if (!row) {
    return false;
  }
  await dbGlobal.delete(rssFeeds).where(and(eq(rssFeeds.id, feedId), eq(rssFeeds.userId, userId)));
  return true;
}

export async function listItemsForUser(userId: number, feedId?: number) {
  const cond = feedId !== undefined ? and(eq(rssItems.userId, userId), eq(rssItems.feedId, feedId)) : eq(rssItems.userId, userId);
  return dbGlobal.select().from(rssItems).where(cond).orderBy(desc(rssItems.publishedAt), desc(rssItems.id)).limit(500);
}

export async function updateItemVisibility(userId: number, itemId: number, visibility: "private" | "unlisted" | "public") {
  const [existing] = await dbGlobal
    .select()
    .from(rssItems)
    .where(and(eq(rssItems.id, itemId), eq(rssItems.userId, userId)))
    .limit(1);
  if (!existing) {
    return null;
  }
  const shareToken = visibilityShareToken(visibility, existing.shareToken);
  await dbGlobal
    .update(rssItems)
    .set({ visibility, shareToken })
    .where(and(eq(rssItems.id, itemId), eq(rssItems.userId, userId)));
  const [row] = await dbGlobal
    .select()
    .from(rssItems)
    .where(and(eq(rssItems.id, itemId), eq(rssItems.userId, userId)))
    .limit(1);
  return row ?? null;
}

export async function listPublicRssItemsBySlug(publicSlug: string) {
  const rows = await dbGlobal
    .select({ it: rssItems })
    .from(rssItems)
    .innerJoin(users, eq(rssItems.userId, users.id))
    .where(
      and(
        eq(users.publicSlug, publicSlug),
        eq(users.status, "active"),
        eq(rssItems.visibility, "public"),
      ),
    )
    .orderBy(desc(rssItems.publishedAt), desc(rssItems.id))
    .limit(200);
  return rows.map((r) => r.it);
}

export async function getUnlistedRssItem(publicSlug: string, shareToken: string) {
  const [row] = await dbGlobal
    .select({ it: rssItems })
    .from(rssItems)
    .innerJoin(users, eq(rssItems.userId, users.id))
    .where(
      and(
        eq(users.publicSlug, publicSlug),
        eq(users.status, "active"),
        eq(rssItems.visibility, "unlisted"),
        eq(rssItems.shareToken, shareToken),
      ),
    )
    .limit(1);
  return row?.it ?? null;
}

type ParsedItem = {
  guid?: string;
  canonicalUrl: string;
  title?: string;
  summary?: string;
  contentSnippet?: string;
  author?: string;
  publishedAt?: Date;
};

function normalizeLink(link: unknown): string | undefined {
  if (typeof link === "string") {
    return link;
  }
  if (link && typeof link === "object" && "@_href" in link) {
    return String((link as { "@_href": string })["@_href"]);
  }
  return undefined;
}

function parseFeedXml(xml: string): { title?: string; siteUrl?: string; items: ParsedItem[] } {
  const parser = new XMLParser({
    ignoreAttributes: false,
    attributeNamePrefix: "@_",
    isArray: (name) => name === "item" || name === "entry",
  });
  const doc = parser.parse(xml) as Record<string, unknown>;

  if (doc.rss && typeof doc.rss === "object") {
    const channel = (doc.rss as { channel?: Record<string, unknown> }).channel;
    if (!channel) {
      return { items: [] };
    }
    const rawItems = channel.item;
    const itemsArr = Array.isArray(rawItems) ? rawItems : rawItems ? [rawItems] : [];
    const items: ParsedItem[] = [];
    for (const it of itemsArr as Record<string, unknown>[]) {
      const link = normalizeLink(it.link) ?? normalizeLink(it.guid);
      if (!link) {
        continue;
      }
      const guid = typeof it.guid === "string" ? it.guid : typeof it.guid === "object" && it.guid && "#text" in (it.guid as object)
        ? String((it.guid as { "#text": string })["#text"])
        : undefined;
      let pub: Date | undefined;
      if (typeof it.pubDate === "string") {
        const d = new Date(it.pubDate);
        if (!Number.isNaN(d.getTime())) {
          pub = d;
        }
      }
      items.push({
        guid,
        canonicalUrl: link,
        title: typeof it.title === "string" ? it.title : undefined,
        summary:
          typeof it.description === "string"
            ? it.description.slice(0, 4000)
            : typeof it["content:encoded"] === "string"
              ? String(it["content:encoded"]).slice(0, 4000)
              : undefined,
        contentSnippet: typeof it.description === "string" ? it.description.slice(0, 500) : undefined,
        author: typeof it.author === "string" ? it.author : undefined,
        publishedAt: pub,
      });
    }
    return {
      title: typeof channel.title === "string" ? channel.title : undefined,
      siteUrl: typeof channel.link === "string" ? channel.link : undefined,
      items,
    };
  }

  if (doc.feed && typeof doc.feed === "object") {
    const feed = doc.feed as Record<string, unknown>;
    const rawEntries = feed.entry;
    const entries = Array.isArray(rawEntries) ? rawEntries : rawEntries ? [rawEntries] : [];
    const items: ParsedItem[] = [];
    for (const en of entries as Record<string, unknown>[]) {
      const link = normalizeLink(en.link) ?? normalizeLink(en.id);
      if (!link) {
        continue;
      }
      const guid = typeof en.id === "string" ? en.id : undefined;
      let pub: Date | undefined;
      if (typeof en.updated === "string") {
        const d = new Date(en.updated);
        if (!Number.isNaN(d.getTime())) {
          pub = d;
        }
      }
      items.push({
        guid,
        canonicalUrl: link,
        title: typeof en.title === "string" ? en.title : typeof en.title === "object" && en.title && "#text" in (en.title as object)
          ? String((en.title as { "#text": string })["#text"])
          : undefined,
        summary: typeof en.summary === "string" ? en.summary.slice(0, 4000) : undefined,
        contentSnippet: typeof en.summary === "string" ? en.summary.slice(0, 500) : undefined,
        author:
          typeof en.author === "string"
            ? en.author
            : typeof en.author === "object" && en.author && "name" in (en.author as object)
              ? String((en.author as { name?: string }).name)
              : undefined,
        publishedAt: pub,
      });
    }
    return {
      title:
        typeof feed.title === "string"
          ? feed.title
          : typeof feed.title === "object" && feed.title && "#text" in (feed.title as object)
            ? String((feed.title as { "#text": string })["#text"])
            : undefined,
      siteUrl: typeof feed.id === "string" ? feed.id : undefined,
      items,
    };
  }

  return { items: [] };
}

async function readResponseBody(res: Response): Promise<string> {
  const reader = res.body?.getReader();
  if (!reader) {
    return await res.text();
  }
  const chunks: Uint8Array[] = [];
  let total = 0;
  while (true) {
    const { done, value } = await reader.read();
    if (done) {
      break;
    }
    if (value) {
      total += value.length;
      if (total > MAX_BODY_BYTES) {
        reader.cancel();
        throw new Error("响应过大");
      }
      chunks.push(value);
    }
  }
  const all = new Uint8Array(total);
  let off = 0;
  for (const c of chunks) {
    all.set(c, off);
    off += c.length;
  }
  return new TextDecoder().decode(all);
}

export async function syncFeed(feedId: number): Promise<{ ok: boolean; error?: string }> {
  const [feed] = await dbGlobal.select().from(rssFeeds).where(eq(rssFeeds.id, feedId)).limit(1);
  if (!feed) {
    return { ok: false, error: "feed not found" };
  }
  try {
    assertSafeRssUrl(feed.feedUrl);
  } catch (e) {
    const msg = e instanceof RssUrlUnsafeError ? e.message : "unsafe url";
    await dbGlobal
      .update(rssFeeds)
      .set({ lastError: msg, lastFetchedAt: new Date() })
      .where(eq(rssFeeds.id, feedId));
    return { ok: false, error: msg };
  }

  const ac = new AbortController();
  const t = setTimeout(() => ac.abort(), FETCH_TIMEOUT_MS);
  try {
    const res = await fetch(feed.feedUrl, {
      signal: ac.signal,
      headers: { "User-Agent": "PersonPanelRSS/1.0" },
      redirect: "follow",
    });
    if (!res.ok) {
      throw new Error(`HTTP ${res.status}`);
    }
    const xml = await readResponseBody(res);
    const parsed = parseFeedXml(xml);

    await dbGlobal
      .update(rssFeeds)
      .set({
        title: parsed.title ?? feed.title,
        siteUrl: parsed.siteUrl ?? feed.siteUrl,
        lastFetchedAt: new Date(),
        lastError: null,
      })
      .where(eq(rssFeeds.id, feedId));

    for (const it of parsed.items) {
      const dedupeCond = it.guid
        ? and(eq(rssItems.feedId, feedId), eq(rssItems.guid, it.guid))
        : and(eq(rssItems.feedId, feedId), eq(rssItems.canonicalUrl, it.canonicalUrl));
      const existing = await dbGlobal
        .select({ id: rssItems.id })
        .from(rssItems)
        .where(dedupeCond)
        .limit(1);
      if (existing.length > 0) {
        continue;
      }
      const id = await nextIntegerId(rssItems, rssItems.id);
      await dbGlobal.insert(rssItems).values({
        id,
        userId: feed.userId,
        feedId,
        guid: it.guid ?? null,
        canonicalUrl: it.canonicalUrl,
        title: it.title ?? null,
        summary: it.summary ?? null,
        contentSnippet: it.contentSnippet ?? null,
        author: it.author ?? null,
        publishedAt: it.publishedAt ?? null,
        visibility: "private",
        shareToken: null,
      });
    }
    return { ok: true };
  } catch (e) {
    const msg = e instanceof Error ? e.message : String(e);
    await dbGlobal
      .update(rssFeeds)
      .set({ lastError: msg, lastFetchedAt: new Date() })
      .where(eq(rssFeeds.id, feedId));
    return { ok: false, error: msg };
  } finally {
    clearTimeout(t);
  }
}

export async function syncDueFeedsForUser(userId: number) {
  const feeds = await listFeedsForUser(userId);
  const now = Date.now();
  for (const f of feeds) {
    const intervalMs = (f.pollIntervalMinutes ?? DEFAULT_POLL_MINUTES) * 60_000;
    const last = f.lastFetchedAt ? f.lastFetchedAt.getTime() : 0;
    if (now - last >= intervalMs) {
      await syncFeed(f.id);
    }
  }
}

export async function syncAllDueFeeds() {
  const allFeeds = await dbGlobal.select().from(rssFeeds);
  const now = Date.now();
  for (const f of allFeeds) {
    const intervalMs = (f.pollIntervalMinutes ?? DEFAULT_POLL_MINUTES) * 60_000;
    const last = f.lastFetchedAt ? f.lastFetchedAt.getTime() : 0;
    if (now - last >= intervalMs) {
      await syncFeed(f.id);
    }
  }
}