/**
 * Service layer for `quote_items` writes.
 *
 * Why a service module (and not just inline PB calls in the route):
 *   - Per `AGENTS.md` data-layer discipline: new endpoints put
 *     business logic in `src/lib/server/<feature>-service.ts` and expose
 *     it via a thin route handler. Don't reach for `pb-helpers.ts`.
 *   - Multiple call sites will need to create quote_items (the existing
 *     AI processor, the existing `quotes.create_from_email` path, the
 *     upcoming "Add item" UI on the process page). Centralising the
 *     validation + denormalisation here keeps all three on the same
 *     contract.
 *
 * Field conventions (mirrored from the existing POST /api/v1/quote_items):
 *   - `description` is required and trimmed; empty/whitespace is rejected.
 *   - `quantity` defaults to 1; must be > 0 when provided.
 *   - `quote_number` is denormalised from the parent quote so downstream
 *     review/approve/sprint flows can read it without a join.
 *   - `is_processed` is forced to `false` (newly created rows are drafts).
 *   - `pricing_source` defaults to "manual" when not provided.
 */

import { getAdminPocketBase } from "./pocketbase-admin";

/**
 * Derive `selling_price` from `cost_price * (1 + markup/100)` when the
 * caller has supplied both cost and markup but omitted selling_price.
 *
 * Used by the PATCH, bulk_update, and re-price paths so the agent
 * doesn't have to compute selling_price itself. Marked explicit in the
 * hermes-skill.md workflow doc so the behaviour is documented.
 *
 * Pure — easy to unit-test:
 *
 *   deriveSellingPriceIfOmitted({ cost_price: 2.39, markup: 30 })
 *     → { cost_price: 2.39, markup: 30, selling_price: 3.11 }
 *
 *   deriveSellingPriceIfOmitted({ cost_price: 2.39, markup: 30, selling_price: 4.00 })
 *     → { cost_price: 2.39, markup: 30, selling_price: 4.00 }  // explicit wins
 *
 *   deriveSellingPriceIfOmitted({ cost_price: 0 })
 *     → { cost_price: 0 }  // can't derive, no markup supplied
 *
 *   deriveSellingPriceIfOmitted({ cost_price: 1, markup: NaN })
 *     → { cost_price: 1, markup: NaN }  // non-finite markup, leave alone
 */
export function deriveSellingPriceIfOmitted(
  patch: Record<string, unknown>,
): Record<string, unknown> {
  if (
    patch.selling_price !== undefined ||
    patch.cost_price === undefined ||
    patch.markup === undefined
  ) {
    return patch;
  }
  const cost = Number(patch.cost_price);
  const markup = Number(patch.markup);
  if (!Number.isFinite(cost) || !Number.isFinite(markup)) {
    return patch;
  }
  const selling = Math.round(cost * (1 + markup / 100) * 100) / 100;
  return { ...patch, selling_price: selling };
}

export type CreateQuoteItemInput = {
  quoteId: string;
  description: string;
  quantity?: number;
  unit?: string;
  sku?: string;
  supplier?: string | null;
  category?: string | null;
  cost_price?: number;
  selling_price?: number;
  markup?: number;
  notes?: string;
  pricing_source?: string;
  pricing_notes?: string;
  /** 15-char PB id of the catalogue row this line was sourced from.
   *  Stored verbatim on `matched_price_list_id` so the catalogue tab
   *  can trace the line back to its origin. */
  matched_price_list_id?: string;
  /** Optional caller token forwarded by the route for audit. Not used
   *  for auth (the route uses admin PB on the server); kept here so a
   *  later audit-log row can stamp the actual operator. */
  callerToken?: string;
};

export type CreateQuoteItemResult = {
  id: string;
  quote_items: Record<string, unknown>;
  /** True when the create was deduped against a row created within
   *  the last `IDEMPOTENCY_WINDOW_MS` ms. Callers should return 200
   *  (not 201) and skip downstream side-effects in this case. */
  idempotent?: boolean;
};

/**
 * Window for `quote_items.create` idempotency. Network retries,
 * double-clicks, and "AI auto-fill ran twice" all hit within this
 * window; older rows aren't dedupe candidates because a deliberate
 * re-add of the same line 10 minutes later is a legitimate operator
 * action (e.g. editing the description and re-running the agent).
 */
export const IDEMPOTENCY_WINDOW_MS = 60_000;

export class CreateQuoteItemError extends Error {
  constructor(
    message: string,
    public readonly status: number = 400,
  ) {
    super(message);
    this.name = "CreateQuoteItemError";
  }
}

export async function createQuoteItem(
  input: CreateQuoteItemInput,
): Promise<CreateQuoteItemResult> {
  const quoteId = (input.quoteId || "").trim();
  const description = (input.description || "").trim();
  if (!quoteId) {
    throw new CreateQuoteItemError("quoteId is required");
  }
  if (!description) {
    throw new CreateQuoteItemError(
      "description is required (non-empty after trim)",
    );
  }

  let quantity = 1;
  if (input.quantity !== undefined && input.quantity !== null) {
    const q = Number(input.quantity);
    if (!Number.isFinite(q) || q <= 0) {
      throw new CreateQuoteItemError("quantity must be a finite number > 0");
    }
    quantity = q;
  }

  // F.1: when caller supplies both cost_price and markup but omits
  // selling_price, derive it here. Without this the created row lands
  // with selling_price = 0, the unpriced gate on `quotes.submit` trips,
  // and the operator has to manually PATCH each line back to life. The
  // REST PATCH path (quote_items/[id]) and the MCP `quote_items.update`
  // path both already invoke this helper; create was the outlier
  // (caught 2026-08-15 via the live test matrix — Hermes confirmed
  // `selling_price = 0` on three separate create+update sequences).
  const derived = deriveSellingPriceIfOmitted({
    cost_price: input.cost_price,
    markup: input.markup,
    selling_price: input.selling_price,
  });

  const pb = await getAdminPocketBase();

  // Confirm the parent quote exists and grab its quote_number for
  // denormalisation. PB will throw a 404 on the create below if the
  // relation is missing, but a clean 404 here is a better error
  // surface for the UI.
  let quoteNumber = "";
  try {
    const parent = await pb.collection("quotes").getOne(quoteId, {
      fields: "id,quote_number",
    });
    quoteNumber = String(parent.quote_number || "");
  } catch (err) {
    const message = err instanceof Error ? err.message : "Unknown PB error";
    // PB's "Failed to create record" or "missing relation" both map
    // to 404 here.
    const isMissing = /Failed to create record|not found|missing/i.test(message);
    throw new CreateQuoteItemError(
      `parent quote ${quoteId} not found: ${message}`,
      isMissing ? 404 : 500,
    );
  }

  // Idempotency: if a row with the same (quote_id, description, sku)
  // was created within the last IDEMPOTENCY_WINDOW_MS, return it and
  // skip the create. Network retries / double-clicks / "AI auto-fill
  // ran twice" all land here — a duplicate is almost always a mistake.
  // Older rows are NOT dedupe candidates: an operator who deliberately
  // re-adds the same line 10 minutes later is doing real work.
  const sku = typeof input.sku === "string" ? input.sku : "";
  const existing = await findRecentDuplicateQuoteItem(
    pb,
    quoteId,
    description,
    sku,
  );
  if (existing) {
    return {
      id: String(existing.id),
      quote_items: existing,
      idempotent: true,
    };
  }

  let created: Record<string, unknown>;
  try {
    created = await pb.collection("quote_items").create({
      quote: quoteId,
      quote_number: quoteNumber,
      description,
      quantity,
      cost_price: Number(input.cost_price) || 0,
      // Read selling_price through the derive result so the F.1
      // auto-derive (cost × (1 + markup/100)) actually fires on
      // create. See derived computation above.
      selling_price: Number(derived.selling_price) || 0,
      markup: Number(input.markup) || 0,
      sku: typeof input.sku === "string" ? input.sku : "",
      unit: typeof input.unit === "string" ? input.unit : "",
      supplier:
        typeof input.supplier === "string" && input.supplier
          ? input.supplier
          : null,
      category:
        typeof input.category === "string" && input.category
          ? input.category
          : null,
      notes: typeof input.notes === "string" ? input.notes : "",
      pricing_source:
        typeof input.pricing_source === "string"
          ? input.pricing_source
          : "manual",
      pricing_notes:
        typeof input.pricing_notes === "string" ? input.pricing_notes : "",
      matched_price_list_id:
        typeof input.matched_price_list_id === "string" &&
        input.matched_price_list_id
          ? input.matched_price_list_id
          : "",
      is_processed: false,
    });
  } catch (err) {
    const message = err instanceof Error ? err.message : "Failed to create quote_item";
    throw new CreateQuoteItemError(message, 500);
  }

  return {
    id: String(created.id),
    quote_items: created,
  };
}

/**
 * Look for a recent duplicate quote_item row — same parent quote,
 * same description, same SKU — created within the last `windowMs`.
 * Returns the full row (caller usually re-emits it as the create
 * response) or `null` when no dedupe candidate exists.
 *
 * Why this exists: the AI auto-fill pipeline and the agent's
 * `quote_items.create` both retry on transient errors; without a
 * dedupe window a single user click or one network blip turns into
 * two identical lines. Scoping the window to 60 seconds (rather
 * than "ever") means a deliberate operator re-add 10 minutes later
 * is still permitted.
 *
 * Returns `null` on PB errors (filter syntax glitch, transient
 * connectivity) rather than throwing — a duplicate-prevention
 * feature must not block legitimate creates.
 */
export async function findRecentDuplicateQuoteItem(
  pb: Awaited<ReturnType<typeof getAdminPocketBase>>,
  quoteId: string,
  description: string,
  sku: string,
  windowMs: number = IDEMPOTENCY_WINDOW_MS,
): Promise<Record<string, unknown> | null> {
  const escapedDesc = description.replace(/"/g, '\\"');
  const escapedSku = sku.replace(/"/g, '\\"');
  // PB datetime filters accept RFC3339 with millisecond precision.
  // We subtract the window once per call so the boundary is stable
  // for the duration of the create.
  const since = new Date(Date.now() - windowMs).toISOString();
  const filter =
    `quote = "${quoteId}" && ` +
    `description = "${escapedDesc}" && ` +
    `sku = "${escapedSku}" && ` +
    `created >= "${since}"`;
  try {
    const result = await pb
      .collection("quote_items")
      .getList(1, 1, { filter, fields: "id,description,sku,quote,created" });
    return (result.items[0] as Record<string, unknown> | undefined) ?? null;
  } catch {
    // Don't block legitimate creates on a dedupe-lookup failure.
    return null;
  }
}