import { getAdminPocketBase } from "./pocketbase-admin";
import type { Quote, Customer, Company } from "@/lib/types";

/**
 * Server-side quote pipeline used by the MCP layer (n8n) and internal API routes.
 *
 * This module is the canonical home for all email-to-quote business logic.
 * It deliberately avoids the pitfalls of the old Django implementation:
 *
 * - No fuzzy customer/company matching — only exact + normalized.
 * - No fabricated cost or selling prices on AI-extracted items.
 * - No racy `last + 1` quote number generation — uses a PocketBase-side
 *   atomic counter.
 * - Replies are written to the `quote_replies` collection, never to a
 *   text blob on `quotes.notes`.
 * - Idempotency: the same email (by Message-ID) cannot create two quotes.
 */

const QUOTES_COLLECTION = "quotes";
const QUOTE_ITEMS_COLLECTION = "quote_items";
const QUOTE_ATTACHMENTS_COLLECTION = "quote_attachments";
const QUOTE_REPLIES_COLLECTION = "quote_replies";
const QUOTE_COUNTERS_COLLECTION = "quote_counters";
const CUSTOMERS_COLLECTION = "customers";
const COMPANIES_COLLECTION = "companies";

const QUOTE_NUMBER_REGEX = /(?:Re:\s*)?(?:Quotation|Quote)\s+Q-(\d{4})-(\d{2})-(\d{3})/i;

/**
 * Sentinel customer for emails with no From: header. PB enforces
 * `required=true` on `quotes.customer`, so we can't pass null. Instead,
 * every email intake with an empty `from_email` is linked to this single
 * stable customer. The quoter reassigns in the quote-editing UI if/when
 * they know who the real sender is.
 *
 * The email domain `no-from.wfdash.local` is impossible to confuse with a
 * real address; the description makes the role explicit.
 */
const UNKNOWN_SENDER_CUSTOMER_EMAIL = "unknown-sender@no-from.wfdash.local";
const UNKNOWN_SENDER_CUSTOMER_NAME = "Unknown Sender";
const UNKNOWN_SENDER_CUSTOMER_DESCRIPTION =
  "Auto-created sentinel for emails with no From: header. The quoter reassigns in the quote-editing UI.";

export interface EmailIntakeAttachment {
  filename: string;
  content_type?: string;
  size?: number;
  /** Raw bytes encoded as base64 (no `data:` URL prefix). */
  base64: string;
}

export interface EmailIntakeExtractedItem {
  description?: string;
  quantity?: number;
  unit?: string;
  notes?: string;
}

export interface EmailIntakePayload {
  from_email: string;
  from_name?: string;
  subject: string;
  body_plain?: string;
  body_html?: string;
  /** RFC 5322 Message-ID. Required for dedup. */
  message_id: string;
  in_reply_to?: string;
  received_at?: string;
  extracted_items?: EmailIntakeExtractedItem[];
  attachments?: EmailIntakeAttachment[];
  /** Optional override for company matching — used by the AI extraction layer. */
  company_hint?: string;
}

export interface EmailReplyPayload {
  from_email: string;
  from_name?: string;
  subject: string;
  body_plain?: string;
  body_html?: string;
  message_id?: string;
  in_reply_to?: string;
  received_at?: string;
  quoted_text?: string;
}

export interface CreateQuoteFromEmailResult {
  quote: Quote;
  customer: Customer;
  company: Company | null;
  items: number;
  attachments: number;
  deduped: boolean;
  quote_number: string;
}

export interface AppendReplyResult {
  quote: Quote | null;
  reply: Record<string, unknown> | null;
  matched_by: "in_reply_to" | "subject" | "none";
}

// ──────────────────────────────────────────────────────────────────────────────
// Atomic quote number generation
// ──────────────────────────────────────────────────────────────────────────────

/**
 * Generates the next quote number (`Q-YYYY-MM-NNN`) atomically.
 *
 * Uses the `quote_counters` collection with a unique `(year, month)` index.
 * The `last_seq+` increment operator is evaluated server-side by PocketBase
 * against the current row state, so concurrent callers cannot collide even
 * if they read the counter at the same instant.
 */
export async function generateQuoteNumberServer(): Promise<string> {
  const pb = await getAdminPocketBase();
  const now = new Date();
  const year = now.getFullYear();
  const month = now.getMonth() + 1;

  const counter = await getOrCreateCounter(pb, year, month);
  const updated = await pb.collection(QUOTE_COUNTERS_COLLECTION).update(counter.id, {
    "last_seq+": 1,
  });

  return formatQuoteNumber(year, month, updated.last_seq);
}

async function getOrCreateCounter(
  pb: Awaited<ReturnType<typeof getAdminPocketBase>>,
  year: number,
  month: number
) {
  try {
    return await pb
      .collection(QUOTE_COUNTERS_COLLECTION)
      .getFirstListItem(`year=${year} && month=${month}`);
  } catch (err) {
    // First request for this month — create the counter. If a concurrent
    // caller already created it, swallow the unique-constraint error and
    // re-fetch.
    try {
      return await pb.collection(QUOTE_COUNTERS_COLLECTION).create({
        year,
        month,
        last_seq: 0,
      });
    } catch {
      return await pb
        .collection(QUOTE_COUNTERS_COLLECTION)
        .getFirstListItem(`year=${year} && month=${month}`);
    }
  }
}

function formatQuoteNumber(year: number, month: number, seq: number): string {
  return `Q-${year}-${String(month).padStart(2, "0")}-${String(seq).padStart(3, "0")}`;
}

// ──────────────────────────────────────────────────────────────────────────────
// Customer matching
// ──────────────────────────────────────────────────────────────────────────────

/**
 * Finds an existing customer by exact email match, or creates a new one.
 *
 * Looks up `email`, then `alternative_email`, then `buyer_email` — case
 * insensitive but otherwise an exact equality match. If no match, creates a
 * new customer with a `description` flag marking it as auto-created from
 * email intake (for audit).
 *
 * Never fuzzy-merges. Two customers with the same domain are kept separate
 * until a human reviews them.
 */
export async function findOrCreateCustomer(input: {
  email: string;
  name?: string;
  companyHint?: string;
}): Promise<{ customer: Customer; created: boolean }> {
  const pb = await getAdminPocketBase();
  const email = (input.email || "").trim().toLowerCase();
  if (!email) {
    throw new Error("Customer email is required for findOrCreateCustomer.");
  }

  const exact = await findCustomerByExactEmail(pb, email);
  if (exact) {
    return { customer: exact, created: false };
  }

  const senderDomain = email.split("@")[1] || "";
  const fallbackName = input.name?.trim() || senderDomain || email;
  const fallbackCompany = input.companyHint?.trim() || senderDomain;

  const created = await pb.collection(CUSTOMERS_COLLECTION).create({
    customer: fallbackName,
    email,
    company: fallbackCompany,
    dateadded: new Date().toISOString().slice(0, 10),
    description: "Auto-created from email intake.",
  });
  return { customer: created as Customer, created: true };
}

/**
 * Returns the singleton "Unknown Sender" customer used when an inbound email
 * has no From: header. Created on first use, reused for all subsequent
 * unknown-sender emails. The race-safety pattern (try-create, re-fetch on
 * unique-index failure) mirrors `generateQuoteNumberServer`.
 */
async function findOrCreateUnknownSenderCustomer(
  pb: Awaited<ReturnType<typeof getAdminPocketBase>>
): Promise<{ customer: Customer; created: boolean }> {
  const existing = await findCustomerByExactEmail(pb, UNKNOWN_SENDER_CUSTOMER_EMAIL);
  if (existing) {
    return { customer: existing, created: false };
  }
  try {
    const created = await pb.collection(CUSTOMERS_COLLECTION).create({
      customer: UNKNOWN_SENDER_CUSTOMER_NAME,
      email: UNKNOWN_SENDER_CUSTOMER_EMAIL,
      company: "Unknown",
      dateadded: new Date().toISOString().slice(0, 10),
      description: UNKNOWN_SENDER_CUSTOMER_DESCRIPTION,
    });
    return { customer: created as Customer, created: true };
  } catch (err) {
    // Race: a concurrent intake created the sentinel first. Re-fetch.
    const refetched = await findCustomerByExactEmail(pb, UNKNOWN_SENDER_CUSTOMER_EMAIL);
    if (refetched) {
      return { customer: refetched, created: false };
    }
    throw err;
  }
}

async function findCustomerByExactEmail(
  pb: Awaited<ReturnType<typeof getAdminPocketBase>>,
  email: string
): Promise<Customer | null> {
  const esc = email.replace(/"/g, '\\"');
  // Try the primary email field first, then the two alternates. Each is a
  // separate query — cheap because of PocketBase's text index.
  for (const field of ["email", "alternative_email", "buyer_email"] as const) {
    try {
      const hit = await pb.collection(CUSTOMERS_COLLECTION).getFirstListItem(`${field} = "${esc}"`);
      if (hit) return hit as Customer;
    } catch {
      // 404 — keep looking.
    }
  }
  return null;
}

// ──────────────────────────────────────────────────────────────────────────────
// Company matching
// ──────────────────────────────────────────────────────────────────────────────

/**
 * Finds an existing company by normalized name, or creates a new one.
 *
 * Two-step match:
 *   1. Case-insensitive exact match on `company` field.
 *   2. Normalized match (lowercase, trim, strip common suffixes) on `company`.
 *
 * If neither matches, creates a new record. Never fuzzy-merges.
 */
export async function findOrCreateCompany(input: {
  name?: string;
  address?: string;
}): Promise<{ company: Company | null; created: boolean }> {
  const pb = await getAdminPocketBase();
  const name = (input.name || "").trim();
  if (!name) {
    return { company: null, created: false };
  }

  const exactHit = await findCompanyByCaseInsensitiveExact(pb, name);
  if (exactHit) return { company: exactHit, created: false };

  const normalizedHit = await findCompanyByNormalized(pb, name);
  if (normalizedHit) return { company: normalizedHit, created: false };

  const created = await pb.collection(COMPANIES_COLLECTION).create({
    company: name,
    address: input.address || "",
    vendor: "",
  });
  return { company: created as Company, created: true };
}

async function findCompanyByCaseInsensitiveExact(
  pb: Awaited<ReturnType<typeof getAdminPocketBase>>,
  name: string
): Promise<Company | null> {
  try {
    const hit = await pb
      .collection(COMPANIES_COLLECTION)
      .getFirstListItem(`company = "${name.replace(/"/g, '\\"')}"`);
    return hit as Company;
  } catch {
    return null;
  }
}

async function findCompanyByNormalized(
  pb: Awaited<ReturnType<typeof getAdminPocketBase>>,
  name: string
): Promise<Company | null> {
  const normalized = normalizeCompanyName(name);
  if (!normalized) return null;
  const all = await pb.collection(COMPANIES_COLLECTION).getFullList<Company>({ fields: "id,company" });
  for (const c of all) {
    if (normalizeCompanyName(c.company) === normalized) {
      return c;
    }
  }
  return null;
}

/**
 * Normalizes a company name for comparison: lowercase, trim, collapse spaces,
 * strip common legal suffixes, strip trailing punctuation. Intentionally
 * conservative — only strips things that are unambiguously noise.
 */
export function normalizeCompanyName(input: string): string {
  return (input || "")
    .toLowerCase()
    .replace(/\s+/g, " ")
    .replace(/[.,]+$/g, "")
    .replace(
      /\b(pty ltd|proprietary limited|ltd|limited|inc|incorporated|llc|corp|corporation|holdings|group|co\.?za|company)\b\.?/gi,
      ""
    )
    .replace(/\s+/g, " ")
    .trim();
}

// ──────────────────────────────────────────────────────────────────────────────
// Quote creation from email
// ──────────────────────────────────────────────────────────────────────────────

/**
 * Creates a Quote (and customer, company, items, attachments) from a parsed
 * email payload. Idempotent on `message_id`.
 *
 * The human-opt-in pattern: AI-extracted items are created with
 * `included_in_quote = false` and all prices zero. A human must review and
 * opt each line in via the existing quote processing UI. We never fabricate
 * cost or selling prices.
 */
export async function createQuoteFromEmail(
  payload: EmailIntakePayload
): Promise<CreateQuoteFromEmailResult> {
  // The n8n Parse Email node stamps `(no subject)` / `(no body)` placeholders
  // when an inbound email is missing those headers (a malformed / RFC 5321-
  // violating send). We accept whatever string the caller sends, including
  // the placeholder, rather than 500ing — the office can then see the
  // placeholder quote in the queue and triage manually. The type contract
  // still says `subject: string`, and the n8n side is now contractually
  // obligated to always send a non-empty string.

  // Some senders (notably iCloud/Mail.app) strip the RFC 5322 Message-ID
  // header. We still need a stable dedup key, so synthesize one from the
  // real email identity. The `synth-` prefix and `@wfdash.local` suffix
  // make it visually obvious in PocketBase that this isn't a real header.
  const effectiveMessageId = payload.message_id?.trim() || synthesizeMessageId(payload);

  // Some senders also strip the From: header entirely. PB enforces
  // `required=true` on `quotes.customer`, so an empty `from_email` cannot
  // be passed through as `null`. We compute a single `fromEmail` value and
  // fall back to a sentinel "Unknown Sender" customer at the resolution
  // step below. The `email_sender` field on the quote stores the literal
  // empty string, not a placeholder — the sentinel is only used for the
  // relation.
  const fromEmail = (payload.from_email || "").trim().toLowerCase();

  const pb = await getAdminPocketBase();

  // ── 1. Idempotency: if we already have a quote for this Message-ID, return it.
  const existing = await findQuoteByMessageId(pb, effectiveMessageId);
  if (existing) {
    const itemsCount = await countQuoteItems(pb, existing.id);
    const attsCount = await countQuoteAttachments(pb, existing.id);
    const customer = existing.customer
      ? ((await pb.collection(CUSTOMERS_COLLECTION).getOne(existing.customer)) as Customer)
      : null;
    const company = existing.company
      ? ((await pb.collection(COMPANIES_COLLECTION).getOne(existing.company)) as Company)
      : null;
    return {
      quote: existing,
      customer: customer as Customer,
      company: company as Company | null,
      items: itemsCount,
      attachments: attsCount,
      deduped: true,
      quote_number: existing.quote_number,
    };
  }

  // ── 2. Resolve or create the customer. Empty from_email → sentinel.
  const { customer } = fromEmail
    ? await findOrCreateCustomer({
        email: fromEmail,
        name: payload.from_name,
        companyHint: payload.company_hint,
      })
    : await findOrCreateUnknownSenderCustomer(pb);

  // ── 3. Resolve or create the company. Only the AI's `company_hint` is
  // trusted — the subject is never a fallback, because unparseable emails
  // would otherwise create junk `companies` rows. The quoter picks the
  // company in the form when the AI couldn't find one.
  const { company } = await findOrCreateCompany({
    name: payload.company_hint,
  });

  // ── 4. Generate a quote number.
  const quoteNumber = await generateQuoteNumberServer();

  // ── 5. Create the quote.
  const receivedAt = payload.received_at ? new Date(payload.received_at) : new Date();
  const quote = await pb.collection(QUOTES_COLLECTION).create({
    quote_number: quoteNumber,
    customer: customer.id,
    company: company?.id || null,
    description: payload.subject,
    status: "new",
    notes: "",
    email_sender: fromEmail,
    email_subject: payload.subject,
    email_body: payload.body_plain || payload.body_html || "",
    has_attachments: (payload.attachments?.length ?? 0) > 0,
    email_message_id: effectiveMessageId,
    company_letterhead: "CNL",
  });

  // ── 6. Pre-populate quote items from the AI extraction. Human opt-in only.
  const items = (payload.extracted_items || []).filter((i) => (i.description || "").trim());
  for (const item of items) {
    await pb.collection(QUOTE_ITEMS_COLLECTION).create({
      quote: quote.id,
      description: item.description,
      quote_number: quoteNumber,
      quantity: Number.isFinite(item.quantity) && (item.quantity as number) > 0 ? item.quantity : 1,
      cost_price: 0,
      selling_price: 0,
      markup: 0,
      notes: item.notes || "",
      is_processed: false,
      included_in_quote: false,
    });
  }

  // ── 7. Attachments are uploaded in a follow-up step, NOT here.
  //
  // The previous design embedded all attachments in the single
  // `quotes.create_from_email` POST as base64 in the JSON body. A single
  // 5 MB PDF became ~6.7 MB of base64 in one HTTP request, which the
  // Next.js route handler rejected at its default 1 MB body limit, so
  // the whole create call failed and no quote row was written.
  //
  // The n8n pipeline now calls `quotes.create_from_email` (which creates
  // the quote row + items) and then loops over the attachments, calling
  // `attachments.upload_for_quote` once per file with a small per-call
  // body. Failures are isolated per attachment and don't roll back the
  // quote.
  //
  // We deliberately accept `attachments` in the payload for back-compat
  // with any caller that still sends them, but we no longer act on them
  // here. The result's `attachments` count is always 0 from this path.

  return {
    quote: quote as Quote,
    customer,
    company: company ?? null,
    items: items.length,
    attachments: 0,
    deduped: false,
    quote_number: quoteNumber,
  };
}

async function uploadQuoteAttachment(
  pb: Awaited<ReturnType<typeof getAdminPocketBase>>,
  input: {
    quoteId: string;
    filename: string;
    contentType?: string;
    size?: number;
    base64: string;
    messageId: string;
  }
): Promise<Record<string, unknown>> {
  const buffer = Buffer.from(input.base64, "base64");
  const file = new File([buffer], input.filename, {
    type: input.contentType || "application/octet-stream",
  });
  // The `quote_attachments.uploaded_at` date field is declared as
  // onCreate-auto in `docs/pocketbase/quote_attachments.collection.json`,
  // but the live PB collection in production (set up before the docs
  // schema was finalised) doesn't carry that auto-fill behaviour, and
  // PB rejects the create with `validation_required` if we don't send a
  // value. We send `new Date().toISO()` so the field is populated for
  // both schemas; PB ignores it on the doc schema and stores it on the
  // live one. Cheap and forward-compatible.
  const created = await pb.collection(QUOTE_ATTACHMENTS_COLLECTION).create({
    quote: input.quoteId,
    filename: input.filename,
    file,
    content_type: input.contentType || "application/octet-stream",
    size_bytes: input.size ?? buffer.length,
    email_message_id: input.messageId,
    kind: classifyAttachment(input.contentType, input.filename),
    uploaded_at: new Date().toISOString(),
  });

  // Flip the parent quote's `has_attachments` flag so the office sees
  // the "📎" badge on the quote list. We update unconditionally rather
  // than reading first — `has_attachments` is a bool column, so
  // setting it to `true` on every call is idempotent and avoids a
  // round-trip per attachment.
  try {
    await pb.collection("quotes").update(input.quoteId, { has_attachments: true });
  } catch (e) {
    // Non-fatal: the attachment row is the source of truth, and the
    // flag will get re-synced on the next upload. Log but don't throw.
    console.warn(
      `[uploadQuoteAttachment] failed to set has_attachments=true on quote ${input.quoteId}:`,
      (e as Error)?.message || e
    );
  }

  return created as Record<string, unknown>;
}

/**
 * Public entry point used by the `attachments.upload_for_quote` MCP tool.
 * Uploads a single attachment to the `quote_attachments` collection, linked
 * to an existing quote. The caller (n8n) is expected to call this once per
 * attachment after `quotes.create_from_email` returns the new quote id.
 *
 * Errors propagate (the MCP tool surfaces them) so the office sees which
 * files didn't make it. A failed attachment does NOT roll back the quote —
 * the quote is more valuable than a single bad file, and a quoter can
 * always re-upload the missing file via a future API.
 */
export async function uploadAttachmentForQuote(input: {
  quoteId: string;
  filename: string;
  contentType?: string;
  size?: number;
  base64: string;
  messageId?: string;
}): Promise<Record<string, unknown>> {
  if (!input.quoteId) throw new Error("quoteId is required.");
  if (!input.filename) throw new Error("filename is required.");
  if (!input.base64) throw new Error("base64 is required.");
  const pb = await getAdminPocketBase();
  return uploadQuoteAttachment(pb, {
    quoteId: input.quoteId,
    filename: input.filename,
    contentType: input.contentType,
    size: input.size,
    base64: input.base64,
    messageId: input.messageId || "",
  });
}

function classifyAttachment(contentType: string | undefined, filename: string): string {
  const ct = (contentType || "").toLowerCase();
  const fn = (filename || "").toLowerCase();
  if (ct === "application/pdf" || fn.endsWith(".pdf")) return "pdf";
  if (ct.startsWith("image/") || /\.(png|jpe?g|gif|webp|bmp)$/.test(fn)) return "image";
  if (
    ct.includes("officedocument") ||
    ct.includes("msword") ||
    ct.includes("ms-excel") ||
    /\.(docx?|xlsx?)$/.test(fn)
  ) {
    return "doc";
  }
  return "other";
}

async function countQuoteItems(
  pb: Awaited<ReturnType<typeof getAdminPocketBase>>,
  quoteId: string
): Promise<number> {
  const list = await pb.collection(QUOTE_ITEMS_COLLECTION).getList(1, 1, {
    filter: `quote = "${quoteId}"`,
  });
  return list.totalItems;
}

async function countQuoteAttachments(
  pb: Awaited<ReturnType<typeof getAdminPocketBase>>,
  quoteId: string
): Promise<number> {
  const list = await pb.collection(QUOTE_ATTACHMENTS_COLLECTION).getList(1, 1, {
    filter: `quote = "${quoteId}"`,
  });
  return list.totalItems;
}

// ──────────────────────────────────────────────────────────────────────────────
// Reply handling
// ──────────────────────────────────────────────────────────────────────────────

/**
 * Appends a reply to an existing quote. Match priority:
 *   1. `In-Reply-To` header → look up `quotes.email_message_id`
 *   2. `Q-YYYY-MM-NNN` extracted from subject → look up `quotes.quote_number`
 *   3. Otherwise returns `{ matched_by: 'none' }` so the caller can move the
 *      email to the Unmatched folder.
 *
 * The reply is stored as a `quote_replies` row. We never mutate
 * `quotes.notes` — the human-readable thread is joined at render time.
 */
export async function appendReplyToQuote(
  payload: EmailReplyPayload
): Promise<AppendReplyResult> {
  const pb = await getAdminPocketBase();
  const receivedAt = payload.received_at ? new Date(payload.received_at) : new Date();

  const { quote, matched_by } = await resolveReplyTarget(pb, payload);

  if (!quote) {
    return { quote: null, reply: null, matched_by: "none" };
  }

  const reply = await pb.collection(QUOTE_REPLIES_COLLECTION).create({
    quote: quote.id,
    from_email: payload.from_email,
    from_name: payload.from_name || "",
    subject: payload.subject,
    body_plain: payload.body_plain || "",
    body_html: payload.body_html || "",
    received_at: receivedAt.toISOString(),
    email_message_id: payload.message_id || "",
    in_reply_to: payload.in_reply_to || "",
    quoted_text: payload.quoted_text || "",
  });

  await pb.collection(QUOTES_COLLECTION).update(quote.id, {
    has_new_reply: true,
    last_reply_at: receivedAt.toISOString(),
  });

  return { quote: quote as Quote, reply, matched_by };
}

async function resolveReplyTarget(
  pb: Awaited<ReturnType<typeof getAdminPocketBase>>,
  payload: EmailReplyPayload
): Promise<{ quote: Quote | null; matched_by: AppendReplyResult["matched_by"] }> {
  if (payload.in_reply_to) {
    const q = await findQuoteByMessageId(pb, payload.in_reply_to);
    if (q) return { quote: q, matched_by: "in_reply_to" };
  }
  const quoteNumber = extractQuoteNumberFromSubject(payload.subject);
  if (quoteNumber) {
    try {
      const q = await pb
        .collection(QUOTES_COLLECTION)
        .getFirstListItem(`quote_number = "${quoteNumber}"`);
      return { quote: q as Quote, matched_by: "subject" };
    } catch {
      // fall through
    }
  }
  return { quote: null, matched_by: "none" };
}

export function extractQuoteNumberFromSubject(subject: string): string | null {
  const m = (subject || "").match(QUOTE_NUMBER_REGEX);
  if (!m) return null;
  return `Q-${m[1]}-${m[2]}-${m[3]}`;
}

// ──────────────────────────────────────────────────────────────────────────────
// Lookups
// ──────────────────────────────────────────────────────────────────────────────

/**
 * Looks up a quote by the inbound email's `Message-ID` header. Returns null
 * if no quote matches. Indexed by `quotes.email_message_id`.
 */
export async function findQuoteByMessageId(
  pbArg?: Awaited<ReturnType<typeof getAdminPocketBase>>,
  messageId?: string
): Promise<Quote | null>;
export async function findQuoteByMessageId(messageId: string): Promise<Quote | null>;
export async function findQuoteByMessageId(
  pbOrMessageId: Awaited<ReturnType<typeof getAdminPocketBase>> | string,
  maybeMessageId?: string
): Promise<Quote | null> {
  let pb: Awaited<ReturnType<typeof getAdminPocketBase>>;
  let messageId: string;
  if (typeof pbOrMessageId === "string") {
    pb = await getAdminPocketBase();
    messageId = pbOrMessageId;
  } else {
    pb = pbOrMessageId;
    messageId = maybeMessageId || "";
  }
  if (!messageId) return null;
  const esc = messageId.replace(/"/g, '\\"');
  try {
    const hit = await pb
      .collection(QUOTES_COLLECTION)
      .getFirstListItem(`email_message_id = "${esc}"`);
    return hit as Quote;
  } catch {
    return null;
  }
}

// ──────────────────────────────────────────────────────────────────────────────
// Message-ID synthesis (fallback when the inbound email has no header)
// ──────────────────────────────────────────────────────────────────────────────

/**
 * Builds a stable, deterministic Message-ID for an email that arrived without
 * one. The hash is over `from_email + subject + received_at` so the same
 * email processed twice dedups to the same id. The `synth-` prefix and
 * `@wfdash.local` suffix make it visually obvious in PocketBase that this
 * isn't a real RFC 5322 Message-ID.
 *
 * Collisions are not a correctness concern: two real emails with identical
 * sender + subject + received_at are the same email. The hash is FNV-1a 32-bit
 * which is overkill for this input space but cheap and stable across runs.
 */
export function synthesizeMessageId(payload: {
  from_email: string;
  subject: string;
  received_at?: string;
}): string {
  const input = `${payload.from_email}|${payload.subject}|${payload.received_at ?? ""}`;
  let hash = 0x811c9dc5;
  for (let i = 0; i < input.length; i++) {
    hash ^= input.charCodeAt(i);
    hash = Math.imul(hash, 0x01000193);
  }
  return `synth-${(hash >>> 0).toString(16).padStart(8, "0")}@wfdash.local`;
}