import { useEffect, useMemo, useState } from 'react';
import { Link, useNavigate, useSearchParams } from 'react-router-dom';
import { ArrowLeft, ChevronLeft, ChevronRight, Database, Search, X } from 'lucide-react';
import { useQuery, useZino } from '../api/provider';
import { LAKEHOUSE } from '../api/config';
import type { Tone } from '../api/config';
import type { RecordFilter, Row } from '../api/types';
import { Badge, ErrorNote, Input, Select, Spinner } from '../components/core';
import { CARC, money, num, shortDate, str } from '../format';

/**
 * The claims table — the lakehouse rows themselves, read-only.
 *
 * Reached three ways: from the Lakehouse overview, from the sidebar, and from
 * a finding's numbers ("216 claims" → the exact rows Ava counted). The URL IS
 * the filter set, so a link can be copied into an email and lands on the same
 * rows. Everything is server-side: paging, filtering, search and the total
 * come from /view/recordview against the Databricks-backed record view, and
 * the dropdown options are the distinct values the platform returns for the
 * current filter set.
 */

const PAGE = 50;

/** URL param → record-view column. */
const DIMS: Array<{ key: string; col: string; label: string }> = [
  { key: 'payer', col: 'payer', label: 'Insurer' },
  { key: 'department', col: 'department', label: 'Department' },
  { key: 'status', col: 'status', label: 'Status' },
  { key: 'code', col: 'denial_reason_code', label: 'Reason code' },
  { key: 'appeal', col: 'appeal_status', label: 'Appeal' },
  { key: 'site', col: 'site', label: 'Site' },
  { key: 'desk', col: 'registration_desk', label: 'Desk' },
  { key: 'provider', col: 'provider', label: 'Provider' },
  { key: 'cpt', col: 'procedure_code', label: 'CPT' },
  { key: 'category', col: 'denial_category', label: 'Denial category' },
];
const RANGES: Array<{ from: string; to: string; col: string; label: string }> = [
  { from: 'from', to: 'to', col: 'service_date', label: 'Service date' },
  { from: 'sub_from', to: 'sub_to', col: 'submitted_date', label: 'Submitted' },
  { from: 'dl_from', to: 'dl_to', col: 'appeal_deadline', label: 'Appeal deadline' },
];

const STATUS_TONE: Record<string, Tone> = { paid: 'emerald', partial: 'amber', denied: 'rose', pending: 'slate' };
const APPEAL_LABEL: Record<string, string> = { not_filed: 'not filed', filed: 'filed', overturned: 'overturned', upheld: 'upheld' };

export function ClaimsScreen() {
  const { client } = useZino();
  const [params] = useSearchParams();
  const navigate = useNavigate();
  const page = Math.max(1, Number(params.get('page') ?? '1') || 1);
  const search = params.get('q') ?? '';
  const [draft, setDraft] = useState(search);
  useEffect(() => setDraft(search), [search]);

  const filters = useMemo<RecordFilter[]>(() => {
    const f: RecordFilter[] = [];
    for (const d of DIMS) {
      const v = params.get(d.key);
      if (v) f.push({ field_key: d.col, value: v, data_type: 'string' });
    }
    for (const r of RANGES) {
      const a = params.get(r.from) ?? undefined;
      const b = params.get(r.to) ?? undefined;
      if (a || b) f.push({ field_key: r.col, data_type: 'date', range: { from: a, to: b } });
    }
    return f;
  }, [params]);
  const filtered = filters.length > 0 || !!search;

  const key = params.toString();
  // ORDER BY A UNIQUE COLUMN. Each page is its own query against Spark, and
  // `service_date` has thousands of ties — with a non-unique sort key the
  // engine is free to order tied rows differently per execution, so page 2
  // repeated rows from page 1. `claim_id` is unique and is assigned in date
  // order, so descending is still newest-first, and every page is disjoint.
  const q = useQuery(
    () => client.recordView('dni-rv-claims', { page, limit: PAGE, filters, search, sortBy: 'claim_id', sortDir: 'desc' }),
    [key],
  );
  // The platform caps its count at 10,000; the stats view has the exact
  // table size, which is the number to show when nothing is filtered.
  const stats = useQuery(() => client.rows('dni-rv-lakehouse-tables', { limit: 10 }), [], !filtered);
  const exact = stats.data?.find((r) => str(r.table_name) === 'claims');

  const rows: Row[] = q.data?.data ?? q.data?.records ?? [];
  const pg = q.data?.pagination;
  const total = !filtered && exact ? (num(exact.row_count) ?? null) : (pg?.total_count ?? q.data?.total ?? null);
  const capped = filtered && !!pg?.total_is_capped;
  const pages = total != null ? Math.max(1, Math.ceil(total / PAGE)) : (pg?.total_pages ?? null);
  const options = q.data?.config?.filter_options ?? {};
  const billedOnPage = rows.reduce((t, r) => t + (num(r.billed_amount) ?? 0), 0);

  function go(next: URLSearchParams) {
    next.delete('page');
    navigate(`/claims${next.toString() ? `?${next}` : ''}`);
  }
  function set(k: string, v: string) {
    const next = new URLSearchParams(params);
    if (v) next.set(k, v);
    else next.delete(k);
    go(next);
  }
  function setPage(n: number) {
    const next = new URLSearchParams(params);
    if (n <= 1) next.delete('page');
    else next.set('page', String(n));
    navigate(`/claims?${next}`);
    // The pager sits under the table; without this the new page loads with the
    // viewport still at the bottom, which reads as "nothing changed".
    window.scrollTo({ top: 0, behavior: 'smooth' });
  }
  const opts = (col: string, labels?: Record<string, string>) =>
    ((options[col] ?? []) as unknown[]).map(String).filter(Boolean).map((v) => ({ value: v, label: labels?.[v] ?? v }));

  // Active filters as removable chips, in display order.
  const chips: Array<{ label: string; value: string; remove: string[] }> = [];
  for (const d of DIMS) {
    const v = params.get(d.key);
    if (v) chips.push({ label: d.label, value: d.col === 'appeal_status' ? (APPEAL_LABEL[v] ?? v) : v, remove: [d.key] });
  }
  for (const r of RANGES) {
    const a = params.get(r.from);
    const b = params.get(r.to);
    if (a || b) chips.push({ label: r.label, value: a && b ? `${shortDate(a)} – ${shortDate(b)}` : a ? `from ${shortDate(a)}` : `to ${shortDate(b)}`, remove: [r.from, r.to] });
  }
  if (search) chips.push({ label: 'Search', value: search, remove: ['q'] });

  return (
    <div className="mx-auto max-w-6xl space-y-4">
      <div className="flex flex-wrap items-end gap-3">
        <div className="min-w-0 flex-1">
          <Link to="/lakehouse" className="inline-flex items-center gap-1 text-xs text-muted hover:text-ink">
            <ArrowLeft className="h-3.5 w-3.5" /> Lakehouse
          </Link>
          <h1 className="text-xl font-semibold text-ink">Claims</h1>
          <p className="mt-0.5 inline-flex items-center gap-1.5 text-xs text-faint">
            <Database className="h-3.5 w-3.5" />
            Read-only · {LAKEHOUSE.platform} · {LAKEHOUSE.catalog}.{LAKEHOUSE.schema}.claims
          </p>
        </div>
        <div className="text-right">
          <p className="tnum text-[22px] leading-none font-bold text-ink">
            {total == null ? '—' : `${total.toLocaleString('en-US')}${capped ? '+' : ''}`}
          </p>
          <p className="mt-1 text-xs text-muted">
            {filtered ? 'claims match' : 'claims in the table'}
            {rows.length > 0 ? ` · ${money(billedOnPage)} billed on this page` : ''}
          </p>
        </div>
      </div>

      {/* ---------- Search + filters. Options are the platform's own distinct values. ---------- */}
      <div className="lift rounded-xl border border-line bg-panel px-4 py-3">
        <form
          className="flex flex-wrap items-center gap-2"
          onSubmit={(e) => {
            e.preventDefault();
            set('q', draft.trim());
          }}
        >
          <div className="relative min-w-[16rem] flex-1">
            <Search className="pointer-events-none absolute top-1/2 left-2.5 h-3.5 w-3.5 -translate-y-1/2 text-faint" />
            <div className="[&_input]:pl-8">
              <Input value={draft} onChange={setDraft} placeholder="Search claim id, provider or CPT…" />
            </div>
          </div>
          <button type="submit" className="rounded-md border border-line px-3 py-2 text-sm text-ink hover:bg-panel2">
            Search
          </button>
        </form>
        <div className="mt-3 grid gap-2 sm:grid-cols-3 lg:grid-cols-5">
          <Select value={params.get('payer') ?? ''} onChange={(v) => set('payer', v)} options={opts('payer')} placeholder="All insurers" />
          <Select value={params.get('department') ?? ''} onChange={(v) => set('department', v)} options={opts('department')} placeholder="All departments" />
          <Select value={params.get('status') ?? ''} onChange={(v) => set('status', v)} options={opts('status')} placeholder="Any status" />
          <Select
            value={params.get('code') ?? ''}
            onChange={(v) => set('code', v)}
            options={opts('denial_reason_code').map((o) => ({ ...o, label: CARC[o.value] ? `${o.value} · ${CARC[o.value]}` : o.value }))}
            placeholder="Any reason code"
          />
          <Select value={params.get('appeal') ?? ''} onChange={(v) => set('appeal', v)} options={opts('appeal_status', APPEAL_LABEL)} placeholder="Any appeal status" />
          <Select value={params.get('site') ?? ''} onChange={(v) => set('site', v)} options={opts('site')} placeholder="All sites" />
          <Select value={params.get('desk') ?? ''} onChange={(v) => set('desk', v)} options={opts('registration_desk')} placeholder="All desks" />
          <Select value={params.get('provider') ?? ''} onChange={(v) => set('provider', v)} options={opts('provider')} placeholder="All providers" />
          <div className="flex items-center gap-1.5">
            <span className="shrink-0 text-[11px] text-faint">Service</span>
            <Input type="date" value={params.get('from') ?? ''} onChange={(v) => set('from', v)} />
          </div>
          <div className="flex items-center gap-1.5">
            <span className="shrink-0 text-[11px] text-faint">to</span>
            <Input type="date" value={params.get('to') ?? ''} onChange={(v) => set('to', v)} />
          </div>
        </div>
        {chips.length > 0 && (
          <div className="mt-3 flex flex-wrap items-center gap-2 border-t border-line pt-3">
            {chips.map((c) => (
              <button
                key={c.label}
                type="button"
                onClick={() => {
                  const next = new URLSearchParams(params);
                  for (const k of c.remove) next.delete(k);
                  go(next);
                }}
                title="Remove filter"
                className="inline-flex items-center gap-1.5 rounded-full border border-line bg-panel2/60 px-3 py-1 text-xs text-ink hover:border-brand/60"
              >
                <span className="text-faint">{c.label}</span>
                <span className="font-semibold">{c.value}</span>
                <X className="h-3 w-3 text-faint" />
              </button>
            ))}
            <Link to="/claims" className="text-xs text-muted hover:text-ink">
              Clear all
            </Link>
          </div>
        )}
      </div>

      {q.error && <ErrorNote>{q.error}</ErrorNote>}

      <div className="lift overflow-hidden rounded-xl border border-line bg-panel">
        {q.loading && !q.data ? (
          <Spinner label="Reading the lakehouse…" />
        ) : rows.length === 0 ? (
          <p className="px-5 py-10 text-center text-sm text-faint">No claims match these filters.</p>
        ) : (
          <div className={`overflow-x-auto transition-opacity ${q.loading ? 'opacity-50' : ''}`} aria-busy={q.loading}>
            <table className="w-full text-[13px]">
              <thead>
                <tr className="text-left text-[11px] font-semibold tracking-wide text-faint uppercase">
                  <Th>Claim</Th>
                  <Th>Service</Th>
                  <Th>Insurer</Th>
                  <Th>Department</Th>
                  <Th>Provider</Th>
                  <Th>Procedure</Th>
                  <Th right>Billed</Th>
                  <Th>Status</Th>
                  <Th>Reason</Th>
                  <Th>Appeal</Th>
                  <Th>Deadline</Th>
                </tr>
              </thead>
              <tbody className="divide-y divide-line">
                {rows.map((r) => {
                  const status = str(r.status);
                  const code = str(r.denial_reason_code);
                  return (
                    <tr key={str(r.claim_id)} className="hover:bg-panel2/60">
                      <Td mono>{str(r.claim_id)}</Td>
                      <Td>{shortDate(str(r.service_date).slice(0, 10) || null)}</Td>
                      <Td>{str(r.payer)}</Td>
                      <Td>{str(r.department)}</Td>
                      <Td>{str(r.provider)}</Td>
                      <Td>
                        <span className="tnum text-faint">{str(r.procedure_code)}</span> {str(r.procedure_desc)}
                      </Td>
                      <Td right mono>{money(r.billed_amount)}</Td>
                      <Td>
                        <Badge tone={STATUS_TONE[status] ?? 'slate'}>{status}</Badge>
                      </Td>
                      <Td>
                        {code ? (
                          <span title={CARC[code] ?? str(r.denial_reason_desc)}>
                            <span className="tnum font-semibold">{code}</span> <span className="text-muted">{str(r.denial_reason_desc)}</span>
                          </span>
                        ) : (
                          <span className="text-faint">—</span>
                        )}
                      </Td>
                      <Td>{status === 'denied' ? (APPEAL_LABEL[str(r.appeal_status)] ?? str(r.appeal_status)) : <span className="text-faint">—</span>}</Td>
                      <Td>{status === 'denied' ? shortDate(str(r.appeal_deadline).slice(0, 10) || null) : <span className="text-faint">—</span>}</Td>
                    </tr>
                  );
                })}
              </tbody>
            </table>
          </div>
        )}
        {pages != null && pages > 1 && (
          <div className="flex items-center justify-between border-t border-line px-4 py-2.5 text-xs text-muted">
            <span className="tnum">
              Page {page.toLocaleString('en-US')} of {pages.toLocaleString('en-US')}
              {capped ? ' (count capped by the platform at 10,000)' : ''}
            </span>
            <span className="inline-flex gap-1">
              <PageBtn disabled={page <= 1} onClick={() => setPage(page - 1)} label="Previous page">
                <ChevronLeft className="h-4 w-4" />
              </PageBtn>
              <PageBtn disabled={page >= pages} onClick={() => setPage(page + 1)} label="Next page">
                <ChevronRight className="h-4 w-4" />
              </PageBtn>
            </span>
          </div>
        )}
      </div>
    </div>
  );
}

function Th({ children, right }: { children: React.ReactNode; right?: boolean }) {
  return <th className={`border-b border-line px-3 py-2.5 ${right ? 'text-right' : ''}`}>{children}</th>;
}
function Td({ children, right, mono }: { children: React.ReactNode; right?: boolean; mono?: boolean }) {
  return <td className={`px-3 py-2 align-top text-ink ${right ? 'text-right' : ''} ${mono ? 'tnum' : ''}`}>{children}</td>;
}
function PageBtn({ children, disabled, onClick, label }: { children: React.ReactNode; disabled: boolean; onClick: () => void; label: string }) {
  return (
    <button
      onClick={onClick}
      disabled={disabled}
      aria-label={label}
      className="rounded-md border border-line p-1 text-muted hover:bg-panel2 hover:text-ink disabled:cursor-not-allowed disabled:opacity-40"
    >
      {children}
    </button>
  );
}