import { useState } from 'react';
import { Link, useParams } from 'react-router-dom';
import { ArrowLeft, Brain, Download, Radar } from 'lucide-react';
import { useQuery, useZino } from '../api/provider';
import {
  ACT,
  FINDING_KIND,
  NEEDS_HUMAN,
  RECORD_VIEW,
  STAGES,
  STAGE_TONE,
  actionsFor,
  stageStep,
} from '../api/config';
import { Badge, Button, ErrorNote, Facts, Spinner } from '../components/core';
import { ActivityForm } from '../components/ActivityForm';
import { AvaLive } from '../components/AvaLive';
import { Disclosure, FullStory, Recheck, Recommendations, SqlEvidence, Verdict } from '../components/Findings';
import { Briefing, BriefingSkeleton } from '../components/Briefing';
import { loadBriefing, sliceOf } from '../api/charts';
import type { Action } from '../api/config';
import { dateTime, num, prose, str } from '../format';

/**
 * One investigation, for a person with ninety seconds.
 *
 * ORDER IS THE DESIGN. What happened (one sentence, large) → how much (three
 * numbers) → what she wants approved → the buttons. That is the whole
 * above-the-fold. The full analysis, her evidence and the live trace sit
 * behind disclosures underneath, for the reviewer who wants to check and the
 * sceptic who wants to see the SQL.
 *
 * The exception is while Ava is still working: then the live trace IS the
 * page, because there is nothing else to show yet and watching her query is
 * the demo.
 *
 * POLLING is on while she owns the case (Investigating / Monitoring); when it
 * is with a person nothing moves, so the poll stops.
 */
export function CaseScreen() {
  const { id } = useParams();
  const { client, user } = useZino();
  const [form, setForm] = useState<Action | null>(null);
  const [showWork, setShowWork] = useState(false);
  const [exporting, setExporting] = useState(false);

  const cases = useQuery(
    () =>
      client.rows(RECORD_VIEW, {
        limit: 1,
        filters: [{ field_key: 'instance_id', value: String(id), data_type: 'number' }],
      }),
    [id],
    true,
    6000,
  );
  const row = cases.data?.[0];
  const state = str(row?.current_state_name);
  const aiOwned = state === 'Investigating' || state === 'Monitoring';
  const scanned = str(row?.scanned_summary);
  const flagged = num(row?.flagged_count);
  const kind = str(row?.finding_kind);
  const quiet = flagged === 0 && !str(row?.summary);
  const hasFindings = !!str(row?.summary);

  const slice = row ? sliceOf(row) : null;
  // Chart rows come from six Databricks views through the record-view API. Loaded
  // once there are findings to picture; the slice keys decide which weekly line
  // and which recovery breakdown are drawn.
  const asOf = str(row?.review_to || row?.review_as_of).slice(0, 10) || null;
  // The anchor behind "expiring within 14 days". It is the review's own
  // ceiling date when the reviewer set one, otherwise the lakehouse's latest
  // service date — read from the stats view, NOT from the briefing: the charts
  // take seconds to load and a link rendered without the anchor would silently
  // drop the deadline window and open thousands of rows instead of hundreds.
  const lake = useQuery(() => client.rows('dni-rv-lakehouse-tables', { limit: 10 }), [], !asOf && hasFindings);
  const anchor = asOf ?? str(lake.data?.find((r) => str(r.table_name) === 'claims')?.to_date).slice(0, 10) ?? null;
  const briefing = useQuery(
    () => loadBriefing(client, slice, { kind, asOf }),
    [id, slice?.payer, slice?.department, slice?.code, kind, asOf],
    hasFindings,
  );

  async function exportDeck() {
    if (!row || !briefing.data) return;
    setExporting(true);
    try {
      // pptxgenjs is ~700 KB; nobody pays for it until they ask for slides.
      const { buildDeck } = await import('../lib/slides');
      await buildDeck(row, briefing.data, slice, kind);
    } finally {
      setExporting(false);
    }
  }

  const trace = useQuery(() => client.avaTrace(String(id)), [id], true, aiOwned ? 4000 : 0);
  const decisions = useQuery(() => client.avaDecisions(String(id)), [id], true, aiOwned ? 8000 : 0);

  const actions = actionsFor(state, user?.roles);

  function refresh() {
    cases.refetch();
    trace.refetch();
    decisions.refetch();
  }

  if (cases.loading && !cases.data) return <Spinner label="Loading case…" />;
  if (cases.error) return <ErrorNote>{cases.error}</ErrorNote>;
  if (!row) return <ErrorNote>Case {id} not found.</ErrorNote>;

  const work = <AvaLive steps={trace.data ?? []} decisions={decisions.data ?? []} working={aiOwned} />;

  return (
    <div className="mx-auto max-w-5xl space-y-4">
      <div className="flex flex-wrap items-center gap-3">
        <Link to="/q/review" className="inline-flex items-center gap-1.5 text-sm text-muted hover:text-ink">
          <ArrowLeft className="h-4 w-4" /> Back
        </Link>
        <span className="tnum text-sm text-faint">Case #{str(row.instance_id)}</span>
        <Badge tone={quiet ? 'slate' : (STAGE_TONE[state] ?? 'slate')} dot={aiOwned}>
          {quiet ? 'No findings' : state}
        </Badge>
        {kind && FINDING_KIND[kind] && <Badge tone="violet">{FINDING_KIND[kind]}</Badge>}
        <span className="ml-auto text-[11px] text-faint">
          Daily review · opened {dateTime(row.created_at)}
          {str(row.review_as_of) ? ` · as of ${str(row.review_as_of).slice(0, 10)}` : ''}
        </span>
        {hasFindings && (
          <Button kind="secondary" onClick={exportDeck} busy={exporting} disabled={!briefing.data} title="Export a six-slide briefing (.pptx)">
            <Download className="h-4 w-4" /> Export slides
          </Button>
        )}
      </div>

      <Rail state={state} />

      {/* ---------- Ava still working: the trace is the page ---------- */}
      {aiOwned && !hasFindings && (
        <>
          <section className="lift rounded-xl border border-ai-edge bg-ai-soft px-5 py-4">
            <p className="inline-flex items-center gap-2 text-[11px] font-semibold tracking-wide text-ai uppercase">
              <Brain className="h-4 w-4" /> Review in progress
            </p>
            <p className="mt-1.5 text-[19px] leading-snug font-semibold text-ink">
              Checking all payers, departments and front desks against the 8-week baseline.
            </p>
            <p className="mt-1 text-sm text-muted">
              Typical duration 4–5 minutes. If no change clears the materiality threshold, the case closes with no findings.
            </p>
          </section>
          {work}
        </>
      )}

      {/* ---------- A quiet morning ---------- */}
      {quiet && (
        <section className="lift rounded-xl border border-line bg-panel px-5 py-5">
          <p className="inline-flex items-center gap-2 text-[11px] font-semibold tracking-wide text-faint uppercase">
            <Radar className="h-4 w-4" /> Review complete
          </p>
          <p className="mt-1.5 text-[21px] leading-snug font-semibold text-ink">
            No findings. No material change across payers, departments or front desks.
          </p>
          {scanned && <p className="mt-3 text-sm leading-relaxed whitespace-pre-wrap text-muted">{scanned}</p>}
        </section>
      )}

      {/* ---------- Needs a human ---------- */}
      {state === NEEDS_HUMAN && (
        <section className="lift rounded-xl border border-bad-edge bg-bad-soft px-5 py-4">
          <p className="text-[11px] font-semibold tracking-wide text-bad uppercase">Escalated — requires a decision</p>
          <p className="mt-1.5 text-[17px] leading-snug font-semibold text-ink">
            {prose(row.escalation_reason) || 'No reason recorded.'}
          </p>
        </section>
      )}

      {/* ---------- The findings: what happened, how much, what to approve ---------- */}
      {hasFindings && (
        <>
          <Verdict row={row} slice={slice} kind={kind} anchor={anchor || null} />
          {briefing.data ? (
            <Briefing data={briefing.data} slice={slice} kind={kind} />
          ) : (
            <BriefingSkeleton error={briefing.error} />
          )}
          <Recheck row={row} />
          <Recommendations row={row} />
        </>
      )}

      {/* ---------- The decision ---------- */}
      {actions.length > 0 && (
        <section className="lift rounded-xl border border-warn-edge bg-warn-soft px-5 py-4">
          <p className="text-[11px] font-semibold tracking-wide text-warn uppercase">Review decision</p>
          <div className="mt-3 flex flex-wrap items-start gap-3">
            {actions.map((a) => (
              <div key={a.activity}>
                <Button kind={a.kind} onClick={() => setForm(a)} className="px-5 py-2.5 text-[15px]">
                  {a.label}
                </Button>
                {a.hint && <p className="mt-1 max-w-[17rem] text-[11px] text-muted">{a.hint}</p>}
              </div>
            ))}
          </div>
        </section>
      )}

      {/* ---------- For the reader who wants to check ---------- */}
      {hasFindings && (
        <>
          <FullStory row={row} />
          <SqlEvidence row={row} steps={trace.data ?? []} decisions={decisions.data ?? []} />
          {!aiOwned && (
            <Disclosure
              open={showWork}
              onToggle={() => setShowWork(!showWork)}
              icon={<Brain className="h-4 w-4 text-ai" />}
              title="Activity trace"
              hint="Step-by-step execution log for this review"
              tone="ai"
            >
              <div className="p-3">{work}</div>
            </Disclosure>
          )}
          {aiOwned && work}
        </>
      )}
      {quiet && (
        <>
          <SqlEvidence row={row} steps={trace.data ?? []} decisions={decisions.data ?? []} />
          <Disclosure
            open={showWork}
            onToggle={() => setShowWork(!showWork)}
            icon={<Brain className="h-4 w-4 text-ai" />}
            title="Activity trace"
            hint="Step-by-step execution log — the checks performed for this no-findings result"
            tone="ai"
          >
            <div className="p-3">{work}</div>
          </Disclosure>
        </>
      )}

      {/* ---------- Provenance ---------- */}
      <section className="rounded-xl border border-line bg-panel px-5 py-4">
        <Facts
          cols={3}
          rows={[
            { label: 'Trigger', value: str(row.review_as_of) || str(row.review_from) || str(row.review_to) ? 'Custom run (chosen dates)' : 'Daily review' },
            { label: 'Data as of', value: str(row.review_to || row.review_as_of) ? str(row.review_to || row.review_as_of).slice(0, 10) : 'Latest available' },
            {
              label: 'Analysis window',
              value: str(row.review_from)
                ? `${str(row.review_from).slice(0, 10)} – ${str(row.review_to || row.review_as_of).slice(0, 10) || 'latest'}`
                : row.period_weeks
                  ? `${str(row.period_weeks)} weeks`
                  : '6 weeks',
            },
            ...(str(row.review_note) ? [{ label: 'Reviewer note', value: prose(row.review_note), wide: true }] : []),
            ...(str(row.approval_note) ? [{ label: 'Approval note', value: prose(row.approval_note), wide: true }] : []),
          ]}
        />
      </section>

      {form && (
        <ActivityForm
          open
          onClose={() => setForm(null)}
          activityUid={form.activity}
          instanceId={str(row.instance_id)}
          title={form.label}
          subtitle={form.hint}
          submitLabel={form.label}
          danger={form.kind === 'danger'}
          prefill={form.activity === ACT.APPROVE ? { approval_note: defaultApprovalNote(row) } : undefined}
          onDone={refresh}
        />
      )}
    </div>
  );
}

/** The five states, as a rail. Needs Human is off the rail on purpose: it is
 *  not a step forward, it is the case leaving the track. */
function Rail({ state }: { state: string }) {
  if (state === NEEDS_HUMAN) return null;
  const at = stageStep(state);
  return (
    <ol className="flex flex-wrap items-center gap-1.5">
      {STAGES.map((s, i) => {
        const done = at > i;
        const here = at === i;
        return (
          <li key={s} className="flex items-center gap-1.5">
            <span
              className={`rounded-full px-2.5 py-1 text-[11px] font-semibold ${
                here ? 'bg-brand text-brand-fg' : done ? 'bg-good-soft text-good ring-1 ring-good-edge ring-inset' : 'bg-panel2 text-faint'
              }`}
            >
              {s}
            </span>
            {i < STAGES.length - 1 && <span aria-hidden="true" className="h-px w-3 bg-line" />}
          </li>
        );
      })}
    </ol>
  );
}

function defaultApprovalNote(row: Record<string, unknown>): string {
  const recoverable = row.recoverable_amount;
  return recoverable
    ? `Approved. Proceed with the recommended appeals and process changes. Expected recovery $${Number(recoverable).toLocaleString('en-US')}.`
    : 'Approved. Proceed with the recommended actions.';
}