import { useEffect, useState } from "react";
import { useApp } from "../state/store";
import { api } from "../lib/api";
import { wizardApi } from "../lib/wizardApi";
import { Branch, Layers, Pulse } from "../components/icons";

export type HubKey = "procurement" | "hr" | "it";

interface HubSpec {
  title: string;
  eyebrow: string;
  intro: string;
  match: RegExp;
  quickActions: { label: string; subject: string; processHint: string }[];
}

const HUBS: Record<HubKey, HubSpec> = {
  procurement: {
    title: "Procurement Hub",
    eyebrow: "Purchase requests, vendor approvals, three-way match",
    intro:
      "Everything a store manager needs to buy something — from a laptop to a forklift — and watch it move through the approval chain.",
    match: /procure|purchase|vendor|\bpo\b|\bp2p\b|requisition|payment|invoice/i,
    quickActions: [
      { label: "Request a new laptop", subject: "store-204-laptop", processHint: "procurement" },
      { label: "Submit a quote for review", subject: "vendor-quote-Q3", processHint: "procurement" },
    ],
  },
  hr: {
    title: "People Hub",
    eyebrow: "Hiring, onboarding, leave, performance",
    intro:
      "All people movements run here. Start an onboarding for a new hire, file a leave request, or kick off a review cycle.",
    match: /onboard|offboard|leave|\bhr\b|hiring|payroll|employee|people operations/i,
    quickActions: [
      { label: "Onboard a new hire", subject: "new-hire-2026Q3", processHint: "onboard" },
      { label: "Request annual leave", subject: "leave-7d-may", processHint: "leave" },
    ],
  },
  it: {
    title: "IT Hub",
    eyebrow: "Tickets, access requests, incident response",
    intro:
      "When something breaks, request access, or you need a new account — file it here and route it to the right on-call.",
    match: /\bit\b|ticket|incident|service operations|access request|sap access|laptop request|hardware request|software request|password reset|account provisioning/i,
    quickActions: [
      { label: "Open an incident", subject: "incident-store-204", processHint: "service" },
      { label: "Request system access", subject: "access-sap-RW", processHint: "access" },
    ],
  },
};

interface PublishedFlow {
  _key: string;
  display_name: string;
  description?: string;
  name?: string;
}

const NON_BUSINESS_SOURCE_CONTEXTS = new Set([
  "EA2_CHAT_THREAD",
  "EA2_CHAT_MSG",
  "EA2_WIZARD_STEP",
]);

async function loadPublishedFlows(): Promise<PublishedFlow[]> {
  const res = await fetch(`${api.config.baseUrl}/api/ea2/flow/processes?limit=200`, {
    headers: { Authorization: `Bearer ${sessionStorage.getItem("fm.mc.token.v1")}` },
  });
  if (!res.ok) throw new Error(`processes ${res.status}`);
  const body = await res.json();
  return ((body?.items || []) as any[])
    .filter(
      (it) =>
        it.status === "published" &&
        it.kind === "definition" &&
        it.display_name &&
        !NON_BUSINESS_SOURCE_CONTEXTS.has(it.source_context)
    )
    .map((it) => ({
      _key: it._key,
      display_name: it.display_name,
      description: it.description,
      name: it.name,
    }));
}

export default function Hub({ hub }: { hub: HubKey }) {
  const spec = HUBS[hub];
  const pushToast = useApp((s) => s.pushToast);
  const setScene = useApp((s) => s.setScene);
  const [flows, setFlows] = useState<PublishedFlow[] | null>(null);
  const [busy, setBusy] = useState<string | null>(null);

  useEffect(() => {
    let cancelled = false;
    loadPublishedFlows()
      .then((rows) => !cancelled && setFlows(rows))
      .catch((err) => !cancelled && pushToast("err", `Catalogue failed: ${err.message}`));
    return () => {
      cancelled = true;
    };
  }, [hub]);

  const matching = (flows || []).filter((f) => spec.match.test(`${f.display_name} ${f.description || ""} ${f.name || ""}`)).slice(0, 8);
  const fallback = (flows || []).slice(0, 6);
  const visible = matching.length > 0 ? matching : fallback;

  const startInstance = async (flowKey: string, subject: string, label: string) => {
    setBusy(flowKey);
    try {
      const res = await wizardApi.startInstance(flowKey, subject);
      pushToast("ok", `Started ${label}${subject ? ` for ${subject}` : ""} — ${res.transaction_id?.slice(0, 8) || "ok"}`);
      setScene("mission");
    } catch (err: any) {
      pushToast("err", `Start failed: ${err.message}`);
    } finally {
      setBusy(null);
    }
  };

  const tryQuickAction = async (label: string, subject: string, processHint: string) => {
    if (!flows) return;
    const match = flows.find((f) =>
      new RegExp(processHint, "i").test(`${f.display_name} ${f.description || ""} ${f.name || ""}`)
    );
    if (!match) {
      pushToast("err", `No published process matching "${processHint}". Build one in Studio.`);
      return;
    }
    await startInstance(match._key, subject, label);
  };

  return (
    <div className="hub-scene">
      <header className="hub-head">
        <div className="mc-hero-eyebrow"><Layers size={12} /> {spec.eyebrow}</div>
        <h2 className="mc-hero-title">{spec.title}</h2>
        <p className="hub-intro">{spec.intro}</p>
      </header>

      <section className="hub-quick">
        <div className="hub-section-label">QUICK ACTIONS</div>
        <div className="hub-quick-grid">
          {spec.quickActions.map((qa) => (
            <button
              key={qa.label}
              className="hub-quick-card"
              onClick={() => tryQuickAction(qa.label, qa.subject, qa.processHint)}
              disabled={!flows}
            >
              <div className="hub-quick-title"><Pulse size={12} /> {qa.label}</div>
              <div className="hub-quick-meta">Looks up "{qa.processHint}" in your catalogue</div>
            </button>
          ))}
        </div>
      </section>

      <section className="hub-catalogue">
        <div className="hub-section-label">RELATED PROCESSES</div>
        {flows === null && <div className="hub-empty">Loading catalogue…</div>}
        {flows !== null && visible.length === 0 && (
          <div className="hub-empty">
            No matching published processes yet. Open the <button className="link-inline" onClick={() => setScene("studio")}>Process Studio</button> to build one.
          </div>
        )}
        <div className="hub-catalogue-grid">
          {visible.map((f) => (
            <div key={f._key} className="hub-flow-card">
              <div className="hub-flow-title"><Branch size={11} /> {f.display_name}</div>
              {f.description && <div className="hub-flow-desc">{f.description.slice(0, 160)}</div>}
              <button
                className="btn btn-secondary"
                disabled={busy === f._key}
                onClick={() => startInstance(f._key, "", f.display_name)}
              >
                {busy === f._key ? "Starting…" : "Start an instance"}
              </button>
            </div>
          ))}
        </div>
      </section>
    </div>
  );
}