import { NextRequest } from "next/server"
import crypto from "crypto"
import { createPost, getPostByGid, updatePost } from "@/lib/db"
import { cleanTitle, slugify } from "@/lib/slug"
import { cacheCover } from "@/lib/cover-cache"

function verifySignature(bodyText: string, signature: string, secret: string): boolean {
  try {
    const hmac = crypto.createHmac("sha256", secret)
    hmac.update(bodyText)
    const expected = hmac.digest("hex")
    return crypto.timingSafeEqual(Buffer.from(expected), Buffer.from(signature))
  } catch {
    return false
  }
}

export async function POST(req: NextRequest) {
  try {
    const rawBody = await req.text()
    const secret = process.env.WEBHOOK_SECRET || process.env.FANSUB_WEBHOOK_SECRET || ""

    if (secret) {
      const signature = req.headers.get("x-signature-256") || req.headers.get("X-Signature-256") || ""
      if (!signature || !verifySignature(rawBody, signature, secret)) {
        return Response.json({ error: "Unauthorized: invalid signature" }, { status: 401 })
      }
    }

    const payload = JSON.parse(rawBody)

    const gid = payload.gid
    const rawTitle = payload.title
    if (!gid || !rawTitle) {
      return Response.json({ error: "Invalid payload: gid and title required" }, { status: 400 })
    }

    const title = cleanTitle(rawTitle)
    const tags = Array.isArray(payload.tags) ? payload.tags : []
    const numPages = payload.num_pages || payload.pages || 0
    const synopsis = payload.synopsis || ""
    const sourceUrl = payload.url || (payload.source === "nhentai" ? `https://nhentai.net/g/${gid}/` : (payload.source === "ehentai" ? `https://e-hentai.org/g/${gid}/` : undefined))

    const slug = slugify(title, gid)

    let post = getPostByGid(gid)
    if (!post) {
      post = createPost({
        gid,
        title,
        title_jpn: payload.title_jpn || undefined,
        artist: payload.artist || undefined,
        parody: payload.parody || undefined,
        tags,
        num_pages: numPages,
        source: payload.source || undefined,
        cover_url: payload.cover_url || undefined,
        url: sourceUrl,
        summary: synopsis || undefined,
        slug,
        published: 1,
      })
    } else {
      post = updatePost(post.id, {
        title,
        title_jpn: payload.title_jpn || post.title_jpn || undefined,
        artist: payload.artist || post.artist || undefined,
        parody: payload.parody || post.parody || undefined,
        tags: tags.length > 0 ? tags : post.tags,
        num_pages: numPages || post.num_pages,
        source: payload.source || post.source || undefined,
        cover_url: payload.cover_url || post.cover_url || undefined,
        url: sourceUrl || post.url || undefined,
        summary: synopsis || post.summary || undefined,
      })!
    }

    await cacheCover(gid)

    return Response.json({
      success: true,
      gid,
      post,
    })
  } catch (err) {
    return Response.json({ error: String(err) }, { status: 500 })
  }
}