import type { AppContext } from "./context.js";
import { generateCode } from "./services/code.js";
import { COL, toView, computeTotal, computeIceTotal, type NocoRecord, type TicketView } from "./fields.js";

export type { TicketView };

export type Resource = "tickets" | "ice";

interface ResourceConfig {
  totalFn: (rec: NocoRecord) => number;
  redeemedCol: string;
  auditIn: "check-in" | "ice";
  auditUndo: "undo" | "ice-undo";
}

const RESOURCES: Record<Resource, ResourceConfig> = {
  tickets: { totalFn: computeTotal, redeemedCol: COL.redeemed, auditIn: "check-in", auditUndo: "undo" },
  ice: { totalFn: computeIceTotal, redeemedCol: COL.iceRedeemed, auditIn: "ice", auditUndo: "ice-undo" },
};

export type LookupResult =
  | { ok: true; found: true; ticket: TicketView }
  | { ok: true; found: false }
  | { ok: false; reason: "db_error"; detail: string };

/** Read a ticket by code. No mutation. Used the instant a QR is scanned. */
export async function lookupByCode(ctx: AppContext, code: string): Promise<LookupResult> {
  try {
    const rec = await ctx.nocodb.findByCode(code);
    if (!rec) return { ok: true, found: false };
    return { ok: true, found: true, ticket: toView(rec) };
  } catch (e: any) {
    return { ok: false, reason: "db_error", detail: e?.message ?? "lookup failed" };
  }
}

export type RedeemResult =
  | { ok: true; ticket: TicketView; checkedIn: number }
  | {
      ok: false;
      reason: "not_found" | "exhausted" | "insufficient" | "db_error";
      ticket?: TicketView;
      detail?: string;
    };

/**
 * Redeem `count` tickets against a code. Serialized per-code so concurrent
 * scans at multiple gates can never over-redeem.
 *
 * A single QR is reusable across visits until Redeemed reaches Total (e.g. a
 * family splitting into two arrivals). `count` is how many people are entering
 * on THIS visit (default 1 for a single walk-up).
 *
 * Positive count that exceeds the remaining balance is rejected (staff can't
 * check in more people than the ticket allows). Negative count undoes a
 * mistaken check-in, clamped so Redeemed never drops below 0.
 */
export async function redeem(
  ctx: AppContext,
  code: string,
  count: number,
  resource: Resource = "tickets",
  operator = "",
): Promise<RedeemResult> {
  const n = Math.trunc(count);
  if (!Number.isFinite(n) || n === 0) {
    return { ok: false, reason: "insufficient", detail: "count must be a non-zero integer" };
  }
  const cfg = RESOURCES[resource];

  // Serialize per (code, resource) so ice and ticket redemptions don't block
  // each other but same-resource scans still can't double-spend.
  return ctx.queue.run(`${resource}:${code}`, async () => {
    let rec: NocoRecord | null;
    try {
      rec = await ctx.nocodb.findByCode(code);
    } catch (e: any) {
      return { ok: false, reason: "db_error", detail: e?.message ?? "lookup failed" };
    }
    if (!rec) return { ok: false, reason: "not_found" };

    const total = cfg.totalFn(rec);
    const redeemed = Number(rec[cfg.redeemedCol]) || 0;
    const remaining = Math.max(0, total - redeemed);

    if (n > 0 && remaining === 0) {
      return { ok: false, reason: "exhausted", ticket: toView(rec) };
    }
    if (n > 0 && n > remaining) {
      return { ok: false, reason: "insufficient", ticket: toView(rec) };
    }

    const next = Math.min(total, Math.max(0, redeemed + n));
    try {
      const updated = await ctx.nocodb.update(rec.Id, {
        [cfg.redeemedCol]: next,
        [COL.lastScanAt]: new Date().toISOString(),
      });
      // Trust our computed `next` but prefer the DB's echoed value if present.
      const confirmed = { ...rec, [cfg.redeemedCol]: Number(updated?.[cfg.redeemedCol] ?? next) };
      const view = toView(confirmed);
      const delta = next - redeemed;
      const remainingAfter = resource === "ice" ? view.ice.remaining : view.remaining;
      if (delta !== 0) {
        // Non-fatal: audit failures never block a check-in.
        await ctx.audit.log({
          code: view.code,
          people: delta,
          name: view.name,
          operator,
          remainingAfter,
          at: new Date().toISOString(),
          action: delta >= 0 ? cfg.auditIn : cfg.auditUndo,
        });
      }
      return { ok: true, ticket: view, checkedIn: delta };
    } catch (e: any) {
      return { ok: false, reason: "db_error", ticket: toView(rec), detail: e?.message ?? "update failed" };
    }
  });
}

/** Substring search by name/email for the admin panel. */
export async function search(ctx: AppContext, query: string): Promise<TicketView[]> {
  const rows = await ctx.nocodb.search(query);
  return rows.map(toView);
}

export interface WebhookInput {
  name: string;
  email: string;
  address?: string;
  isDonor?: boolean;
  carParking?: boolean;
  rvParking?: boolean;
  iceAccess?: boolean;
  iceBags?: number; // prepaid ice bags
  paymentMethod?: string;
  ages: Record<string, number>; // NocoDB age-column title -> count
  submissionKey: string;
}

/** Idempotent ticket creation from a purchase webhook. Returns the code. */
export async function createTicket(
  ctx: AppContext,
  input: WebhookInput,
): Promise<{ status: "created" | "duplicate"; code: string; record: NocoRecord }> {
  const existing = await ctx.nocodb.findBySubmissionKey(input.submissionKey);
  if (existing) {
    return { status: "duplicate", code: String(existing[COL.code] ?? ""), record: existing };
  }

  // Generate a unique code, retrying on the rare collision.
  let code = generateCode();
  for (let attempt = 0; attempt < 5; attempt++) {
    const clash = await ctx.nocodb.findByCode(code);
    if (!clash) break;
    code = generateCode();
  }

  const fields: Record<string, unknown> = {
    [COL.name]: input.name,
    [COL.email]: input.email,
    [COL.code]: code,
    [COL.redeemed]: 0,
    [COL.iceTotal]: input.iceBags ?? 0,
    [COL.iceRedeemed]: 0,
    [COL.submissionKey]: input.submissionKey,
    ...input.ages,
  };
  if (input.address !== undefined) fields[COL.address] = input.address;
  if (input.isDonor !== undefined) fields[COL.isDonor] = input.isDonor;
  if (input.carParking !== undefined) fields[COL.carParking] = input.carParking;
  if (input.rvParking !== undefined) fields[COL.rvParking] = input.rvParking;
  if (input.iceAccess !== undefined) fields[COL.iceAccess] = input.iceAccess;
  if (input.paymentMethod !== undefined) fields[COL.paymentMethod] = input.paymentMethod;

  const record = await ctx.nocodb.create(fields);
  return { status: "created", code, record };
}