import { useEffect, useMemo, useState } from "react";
import { Link, useSearchParams } from "react-router-dom";
import { useTranslation } from "react-i18next";
import { api } from "../api/client";
import type { Dashboard as DashboardData, IntegrationStatus, KnowledgeHealth } from "../api/types";
import { useAuth } from "../context/AuthContext";
import { useDemoGuide } from "../context/DemoGuideContext";
import { useDemoManifest } from "../context/DemoManifestContext";
import { useLocaleFormat } from "../i18n/format";
import { useGreetingPeriod } from "../i18n/useGreetingPeriod";
import { SeverityBadge, StatusBadge } from "../components/Badge";
import { Icon } from "../components/Icons";
import { ErrorState, IntegrationMark, LoadingState, PageHeader, SectionHeading } from "../components/PageChrome";
import { N8N_STATE_META, MCP_STATE_META } from "../data/integrationLabels";
import { describeEvidenceSignal } from "../data/evidenceSignals";
import type { AttentionItem } from "../api/types";

const FLEET_METRIC_KEYS: Array<{ key: keyof DashboardData["metrics"]; labelKey: string; tone: string }> = [
  { key: "available", labelKey: "readiness.available", tone: "ready" },
  { key: "rented", labelKey: "readiness.rented", tone: "neutral" },
  { key: "cleaning", labelKey: "readiness.cleaning", tone: "neutral" },
  { key: "maintenance", labelKey: "readiness.maintenance", tone: "warning" },
  { key: "blocked", labelKey: "readiness.blocked", tone: "critical" },
];

function attentionItemTitle(
  t: (key: string, options?: Record<string, unknown>) => string,
  item: { rule_type: string; link_ref: string },
): string {
  const ruleLabel = t(`quality:ruleTypes.${item.rule_type}`, { defaultValue: item.rule_type.replace(/_/g, " ") });
  return `${ruleLabel} — ${item.link_ref}`;
}

// The backend never emits prose here either -- only stable signal codes + params, exactly
// like the data-quality issue detail page. Multiple signals on one item (e.g. the
// duplicate-customer match) are joined into one readable line for this compact row.
function attentionItemDetail(
  t: (key: string, options?: Record<string, unknown>) => string,
  formatNumber: (value: number) => string,
  item: Pick<AttentionItem, "evidence_signals">,
): string {
  return item.evidence_signals.map((signal) => describeEvidenceSignal(t, formatNumber, signal)).join(" · ");
}

export function Dashboard() {
  const { t } = useTranslation(["dashboard", "common", "integrations", "quality"]);
  const { formatTime, formatShortDate, formatNumber } = useLocaleFormat();
  const greetingPeriod = useGreetingPeriod();
  const { user } = useAuth();
  const { manifest } = useDemoManifest();
  const { openGuide, restart, currentIndex, completed, totalSteps } = useDemoGuide();
  const [searchParams, setSearchParams] = useSearchParams();
  const canSeeQuality = user?.role === "operations_manager";
  const canSeeAutomation = user?.role === "operations_manager";

  useEffect(() => {
    if (searchParams.get("guide") === "start") {
      restart();
      openGuide();
      setSearchParams({}, { replace: true });
    }
    // Only ever react to the initial `?guide=start` marker set by the login screen's
    // "Start begeleide demo" CTA, so this intentionally runs once on mount.
  }, []);
  const [data, setData] = useState<DashboardData | null>(null);
  const [knowledge, setKnowledge] = useState<KnowledgeHealth | null>(null);
  const [integrationStatus, setIntegrationStatus] = useState<IntegrationStatus | null>(null);
  const [error, setError] = useState<string | null>(null);
  const [severity, setSeverity] = useState("all");
  const [query, setQuery] = useState("");

  useEffect(() => {
    api.get<DashboardData>("/api/v1/dashboard").then(setData).catch(() => setError(t("common:status.error")));
    api.get<KnowledgeHealth>("/api/v1/knowledge/status").then(setKnowledge).catch(() => setKnowledge(null));
  }, []);

  useEffect(() => {
    if (!canSeeAutomation) return;
    api
      .get<IntegrationStatus>("/api/v1/integrations/status")
      .then(setIntegrationStatus)
      .catch(() => setIntegrationStatus(null));
  }, [canSeeAutomation]);

  const attention = useMemo(() => data?.attention_items.filter((item) => {
    const matchesSeverity = severity === "all" || item.severity === severity;
    const haystack = `${attentionItemTitle(t, item)} ${attentionItemDetail(t, formatNumber, item)} ${item.link_ref}`.toLowerCase();
    return matchesSeverity && haystack.includes(query.toLowerCase());
  }) ?? [], [data, query, severity, t, formatNumber]);

  const isUnfiltered = severity === "all" && query === "";
  const attentionTiers = useMemo(() => {
    if (!isUnfiltered) return [{ key: "all", labelKey: "", items: attention.slice(0, 6) }];
    // Keep the initial dashboard queue deliberately bounded. The full evidence-backed
    // queue remains one click away in Data Quality; this view is for deciding what to
    // do next, not for rendering the whole backlog.
    const visible = ["high", "medium", "low"].flatMap((level) => attention.filter((item) => item.severity === level)).slice(0, 6);
    const bySeverity = (level: string) => visible.filter((item) => item.severity === level);
    return [
      { key: "high", labelKey: "attention.tierNow", items: bySeverity("high") },
      { key: "medium", labelKey: "attention.tierToday", items: bySeverity("medium") },
      { key: "low", labelKey: "attention.tierLater", items: bySeverity("low") },
    ].filter((tier) => tier.items.length > 0);
  }, [attention, isUnfiltered]);

  if (error) return <ErrorState message={error} />;
  if (!data) return <LoadingState label={t("common:status.loading")} />;

  const latestRun = data.recent_automation[0];
  const readyCount = manifest?.scenarios.filter((s) => s.ready).length ?? 0;
  const greetingTitle = `${t(`greeting.${greetingPeriod}`)}. ${t(`greetingBody.${greetingPeriod}`)}`;

  return (
    <div className="page dashboard-page">
      <PageHeader eyebrow={t("eyebrow")} title={greetingTitle} description={t("description")} actions={<Link className="button button-secondary" to="/vehicles"><Icon name="fleet" /> {t("viewFleet")}</Link>} />

      <section className="demo-start-panel" aria-label={t("demoStart.title")}>
        <div>
          <Icon name="spark" />
          <div>
            <strong>{t("demoStart.title")}</strong>
            <span>
              {manifest ? t("demoStart.readyCount", { ready: readyCount, total: manifest.scenarios.length }) : t("demoStart.readyCountFallback")}
            </span>
          </div>
        </div>
        <div className="demo-start-actions">
          {user?.role === "operations_manager" && (
            <button type="button" className="button button-secondary" onClick={openGuide}>
              <Icon name="spark" /> {completed.size > 0 ? t("demoStart.resumeGuide", { current: currentIndex + 1, total: totalSteps }) : t("demoStart.startGuide")}
            </button>
          )}
          <Link className="button button-primary" to="/scenarios">{t("demoStart.viewScenarios")} <Icon name="chevron" /></Link>
        </div>
      </section>

      <section className="readiness-band" aria-labelledby="readiness-heading">
        <div className="readiness-label">
          <span className="live-indicator" />
          <div><h2 id="readiness-heading">{t("readiness.title")}</h2><p>{t("readiness.description")}</p></div>
        </div>
        <dl className="readiness-metrics">
          {FLEET_METRIC_KEYS.map((metric) => (
            <div key={metric.key} className={`metric-cell metric-${metric.tone}`}>
              <dt>{t(metric.labelKey)}</dt><dd>{data.metrics[metric.key]}</dd>
            </div>
          ))}
        </dl>
        <Link className="inline-action" to="/vehicles">{t("readiness.openFleet")} <Icon name="chevron" /></Link>
      </section>

      <div className="operations-grid">
        <section className="work-panel attention-panel" aria-labelledby="attention-heading">
          <SectionHeading headingId="attention-heading" title={t("attention.title")} description={t("attention.description", { openIssues: data.metrics.open_quality_issues, workflowExceptions: data.metrics.pending_or_failed_workflows })} action={canSeeQuality ? <Link to="/data-quality">{t("attention.reviewQueue")} <Icon name="chevron" /></Link> : undefined} />
          <div className="queue-controls">
            <label className="compact-search"><Icon name="search" /><span className="visually-hidden">{t("attention.filterAriaLabel")}</span><input value={query} onChange={(event) => setQuery(event.target.value)} placeholder={t("attention.filterPlaceholder")} /></label>
            <label><span className="visually-hidden">{t("attention.severityAriaLabel")}</span><select value={severity} onChange={(event) => setSeverity(event.target.value)}><option value="all">{t("attention.severityAll")}</option><option value="high">{t("attention.severityHigh")}</option><option value="medium">{t("attention.severityMedium")}</option><option value="low">{t("attention.severityLow")}</option></select></label>
          </div>
          {attention.length === 0 ? <p className="quiet-empty"><Icon name="check" /> {t("attention.empty")}</p> : (
            <>
              {attentionTiers.map((tier) => (
                <div key={tier.key} className="attention-tier">
                  {attentionTiers.length > 1 && <p className="attention-tier-label">{t(tier.labelKey)}</p>}
                  <ul className="attention-list">
                    {tier.items.map((item, index) => {
                      const href = item.issue_ref && canSeeQuality
                        ? `/data-quality/${item.issue_ref}`
                        : item.link_type === "vehicle"
                          ? `/vehicles/${item.link_ref}`
                          : null;
                      const title = attentionItemTitle(t, item);
                      return (
                        <li key={`${item.link_ref}-${index}`} className={href ? "row-clickable" : ""}>
                          <SeverityBadge severity={item.severity} />
                          <div className="queue-copy">
                            <p className="attention-title">{title}</p>
                            <p className="attention-detail">{attentionItemDetail(t, formatNumber, item)}</p>
                          </div>
                          <span className="queue-ref">{item.link_ref}</span>
                          <Icon name="chevron" className="row-chevron" />
                          {href && (
                            <Link className="row-link" to={href} aria-label={t("attention.openRecord", { title })}>
                              <span className="visually-hidden">{title}</span>
                            </Link>
                          )}
                        </li>
                      );
                    })}
                  </ul>
                </div>
              ))}
              {isUnfiltered && attention.length > 6 && canSeeQuality && (
                <p className="queue-more"><Link to="/data-quality">{t("attention.remaining", { count: attention.length - 6 })} <Icon name="chevron" /></Link></p>
              )}
            </>
          )}
        </section>

        <section className="work-panel timeline-panel" aria-labelledby="today-heading">
          <SectionHeading headingId="today-heading" title={t("movements.title")} description={t("movements.description")} action={<Link to="/bookings">{t("movements.allBookings")} <Icon name="chevron" /></Link>} />
          {data.today.length === 0 ? <p className="quiet-empty"><Icon name="clock" /> {t("movements.empty")}</p> : (
            <ol className="movement-timeline">
              {data.today.map((item) => (
                <li key={`${item.kind}-${item.booking_ref}`} className="row-clickable">
                  <time dateTime={item.scheduled_at}>{formatTime(item.scheduled_at)}</time>
                  <span className={`timeline-node timeline-${item.kind}`}><Icon name={item.kind === "return" ? "arrow-left" : "chevron"} /></span>
                  <div><span className="movement-kind">{item.kind === "return" ? t("movements.return") : t("movements.departure")}</span><span className="movement-ref">{item.booking_ref}</span><small>{item.vehicle_ref}</small></div>
                  <Link className="row-link" to={`/bookings/${item.booking_ref}`} aria-label={t("movements.openBooking", { ref: item.booking_ref })}>
                    <span className="visually-hidden">{item.booking_ref}</span>
                  </Link>
                </li>
              ))}
            </ol>
          )}
        </section>
      </div>

      <div className="secondary-grid">
        <section className="work-panel integration-panel" aria-labelledby="integration-heading">
          <SectionHeading headingId="integration-heading" title={t("integrationPulse.title")} description={t("integrationPulse.description")} action={canSeeAutomation ? <Link to="/automation">{t("integrationPulse.systemDetail")} <Icon name="chevron" /></Link> : undefined} />
          <ul className="integration-list">
            <li>
              <IntegrationMark kind="n8n" />
              <div>
                <strong>{t("integrationPulse.n8nTitle")}</strong>
                <span>
                  {integrationStatus
                    ? t("integrationPulse.n8nSummary", { succeeded: integrationStatus.n8n.succeeded, failed: integrationStatus.n8n.failed })
                    : latestRun
                      ? t("integrationPulse.n8nLatest", { ref: latestRun.aggregate_ref })
                      : t("integrationPulse.n8nNoEvidence")}
                </span>
              </div>
              {(() => {
                const meta = integrationStatus ? N8N_STATE_META[integrationStatus.n8n.state] : null;
                return (
                  <StatusBadge
                    status={meta?.statusClass ?? "no_events"}
                    label={meta ? t(`integrations:statusLabels.${meta.labelKey}`) : undefined}
                  />
                );
              })()}
            </li>
            <li>
              <IntegrationMark kind="rag" />
              <div>
                <strong>{t("integrationPulse.knowledgeTitle")}</strong>
                <span>{knowledge ? (knowledge.document_count === null ? t("integrationPulse.knowledgeIndexUnknown") : t("integrationPulse.knowledgeSummary", { count: knowledge.document_count })) : t("integrationPulse.knowledgeUnavailable")}</span>
              </div>
              <StatusBadge
                status={knowledge?.available ? "available" : "unavailable"}
                label={
                  knowledge?.available
                    ? t(`integrations:statusLabels.${knowledge.provider === "ragcore" ? "operational" : "demoMode"}`)
                    : t("integrations:statusLabels.unavailable")
                }
              />
            </li>
            <li>
              <IntegrationMark kind="mcp" />
              <div>
                <strong>{t("integrationPulse.mcpTitle")}</strong>
                <span>{integrationStatus?.mcp_hub.registration_enabled ? t("integrationPulse.mcpEnabled") : t("integrationPulse.mcpNotConnected")}</span>
              </div>
              {(() => {
                const meta = integrationStatus ? MCP_STATE_META[integrationStatus.mcp_hub.state] : null;
                return <StatusBadge status={meta?.statusClass ?? "not_configured"} label={meta ? t(`integrations:statusLabels.${meta.labelKey}`) : undefined} />;
              })()}
            </li>
          </ul>
        </section>

        <section className="work-panel recent-panel" aria-labelledby="recent-heading">
          <SectionHeading headingId="recent-heading" title={t("recent.title")} description={t("recent.description")} />
          {data.recent_automation.length === 0 ? <p className="quiet-empty">{t("recent.empty")}</p> : (
            <ul className="recent-list">
              {data.recent_automation.slice(0, 4).map((run) => (
                <li key={run.event_id}><span className="activity-icon"><Icon name="activity" /></span><div><strong>{t(`integrations:ledger.eventTypes.${run.event_type}`, { defaultValue: run.event_type.replace(/_/g, " ") })}</strong><span>{run.aggregate_ref}</span></div><StatusBadge status={run.status} label={t(`integrations:ledger.status${run.status.charAt(0).toUpperCase()}${run.status.slice(1)}`, { defaultValue: run.status })} /><time dateTime={run.occurred_at}>{formatShortDate(run.occurred_at)}</time></li>
              ))}
            </ul>
          )}
        </section>
      </div>
    </div>
  );
}