import "server-only";
import path from "node:path";
import fs from "node:fs/promises";
import crypto from "node:crypto";
import { NextRequest } from "next/server";
import { db, rawDb } from "@/lib/db/client";
import { images } from "@/lib/db/schema";
import { eq } from "drizzle-orm";

const LIBRARY_ROOT = path.join(process.cwd(), "library");
const THUMB_ROOT = path.join(process.cwd(), "data", "thumbs");
const PORTRAIT_ROOT = path.join(process.cwd(), "data", "portraits");

const IMAGE_MIME: Record<string, string> = {
  ".png": "image/png",
  ".jpg": "image/jpeg",
  ".jpeg": "image/jpeg",
  ".webp": "image/webp",
};

const SLOT_LABEL: Record<string, string> = { "1": "p1", "2": "p2", "3": "p3", "4": "p4", "h": "l" };

export async function serveImage(req: NextRequest, lookup: { id?: string | null; code?: string | null }): Promise<Response> {
  let row: typeof images.$inferSelect | undefined;
  if (lookup.id) {
    const numId = Number(lookup.id);
    if (!Number.isFinite(numId)) return new Response("not found", { status: 404 });
    const match = rawDb.prepare(`SELECT id FROM images WHERE id = ? AND deleted_at IS NULL`).get(numId) as { id: number } | undefined;
    if (match) row = db.select().from(images).where(eq(images.id, match.id)).get();
  } else if (lookup.code) {
    // Look up by code. If multiple rows share the code, pick the lowest id (most stable).
    const matches = rawDb.prepare(`
      SELECT id FROM images
      WHERE code = ? AND deleted_at IS NULL AND parent_image_id IS NULL
      ORDER BY id LIMIT 2
    `).all(lookup.code) as Array<{ id: number }>;
    if (matches.length >= 1) {
      row = db.select().from(images).where(eq(images.id, matches[0].id)).get();
    }
  }
  if (!row) return new Response("not found", { status: 404 });

  const etag = `"${row.sha256}"`;
  if (req.headers.get("if-none-match") === etag) {
    return new Response(null, { status: 304, headers: { ETag: etag, "Cache-Control": "public, max-age=0, must-revalidate" } });
  }

  const abs = path.join(LIBRARY_ROOT, row.relPath);
  // Defence in depth: relPath is set internally during ingest, but a
  // malformed backup-import could plant a row with "../" segments. Refuse
  // anything that resolves outside LIBRARY_ROOT.
  const rel = path.relative(LIBRARY_ROOT, abs);
  if (!rel || rel.startsWith("..") || path.isAbsolute(rel)) {
    return new Response("not found", { status: 404 });
  }
  try {
    const buf = await fs.readFile(abs);
    const ext = path.extname(abs).toLowerCase();
    const downloadName = `${row.code ?? `image-${row.id}`}${ext}`;
    return new Response(new Uint8Array(buf), {
      headers: {
        "Content-Type": IMAGE_MIME[ext] ?? "application/octet-stream",
        "Content-Disposition": contentDisposition(downloadName),
        "Cache-Control": "public, max-age=0, must-revalidate",
        ETag: etag,
      },
    });
  } catch {
    return new Response("not found", { status: 404 });
  }
}

/**
 * Produce a Content-Disposition value with a properly RFC 5987-encoded
 * filename. Without this, codes containing characters like `"`, `\`, or
 * non-ASCII bytes would terminate the quoted-string early and produce a
 * malformed header. Real-world risk on this app is small (codes are
 * sanitized at ingest) but the cost of being correct is two lines.
 */
function contentDisposition(filename: string): string {
  // Strip control chars + quotes/backslashes for the legacy fallback;
  // emit the full UTF-8 form via filename* per RFC 5987.
  const safe = filename.replace(/[ -"\\]/g, "_");
  const encoded = encodeURIComponent(filename);
  return `inline; filename="${safe}"; filename*=UTF-8''${encoded}`;
}

export async function serveThumb(name: string): Promise<Response> {
  // Canonical thumbnail filename is either "<sha>.webp" or
  // "<CODE>-<sha>.webp" where the code is uppercase letters/digits/dash.
  // Reject anything else outright; defence-in-depth against path traversal
  // (the regex implicitly forbids "/", "\", "..").
  const m = name.match(/^(?:([A-Z0-9-]{1,40})-)?([a-f0-9]{64})\.webp$/);
  if (!m) {
    return new Response("not found", { status: 404 });
  }
  const sha = m[2];
  const abs = path.join(THUMB_ROOT, name);
  try {
    const buf = await fs.readFile(abs);
    const row = rawDb.prepare(`SELECT code, id FROM images WHERE sha256 = ?`).get(sha) as
      | { code: string | null; id: number }
      | undefined;
    const downloadName = `${row?.code ?? `image-${row?.id ?? sha.slice(0, 8)}`}.webp`;
    return new Response(new Uint8Array(buf), {
      headers: {
        "Content-Type": "image/webp",
        "Content-Disposition": contentDisposition(downloadName),
        "Cache-Control": "public, max-age=31536000, immutable",
      },
    });
  } catch {
    return new Response("not found", { status: 404 });
  }
}

function derivePortraitDownloadName(filename: string): string | null {
  const ext = path.extname(filename).toLowerCase();
  const stem = ext ? filename.slice(0, -ext.length) : filename;
  const newFmt = stem.match(/^(\d+)-([1-4h])-[a-f0-9]+$/);
  const oldFmt = !newFmt ? stem.match(/^(\d+)-[a-f0-9]+$/) : null;
  const m = newFmt ?? oldFmt;
  if (!m) return null;
  const actressId = Number(m[1]);
  const slot = newFmt ? newFmt[2] : "1";
  const row = rawDb.prepare(`SELECT slug FROM actresses WHERE id = ?`).get(actressId) as
    | { slug: string }
    | undefined;
  if (!row) return null;
  const suffix = slot === "1" ? "" : `-${SLOT_LABEL[slot]}`;
  return `${row.slug}${suffix}${ext}`;
}

export async function servePortrait(name: string): Promise<Response> {
  if (name.includes("/") || name.includes("\\") || name.includes("..")) {
    return new Response("not found", { status: 404 });
  }
  const abs = path.join(PORTRAIT_ROOT, name);
  try {
    const buf = await fs.readFile(abs);
    const ext = path.extname(abs).toLowerCase();
    const downloadName = derivePortraitDownloadName(name) ?? name;
    // Hash content so a re-uploaded portrait at the same filename
    // invalidates browser caches; using the filename alone served
    // stale bytes.
    const etag = `"${crypto.createHash("sha256").update(buf).digest("hex")}"`;
    return new Response(new Uint8Array(buf), {
      headers: {
        "Content-Type": IMAGE_MIME[ext] ?? "application/octet-stream",
        "Content-Disposition": contentDisposition(downloadName),
        "Cache-Control": "public, max-age=0, must-revalidate",
        ETag: etag,
      },
    });
  } catch {
    return new Response("not found", { status: 404 });
  }
}