"use client";

// Vendored from family-chart/dist/styles (the package blocks the CSS subpath export).
import "./chart.css";

import Link from "next/link";
import { useParams, useRouter } from "next/navigation";
import { useCallback, useEffect, useMemo, useRef, useState } from "react";

import { api } from "@/lib/api/client";
import type { components } from "@/lib/api/schema";
import { Button } from "@/components/ui/button";
import { FanChart } from "@/components/fan-chart";

type Person = components["schemas"]["PersonRead"];
type Relationship = components["schemas"]["RelationshipRead"];
type Event = components["schemas"]["EventRead"];
type Mode = "landscape" | "portrait" | "fan";

function splitName(name: string | null | undefined): [string, string] {
  const t = (name ?? "").trim().split(/\s+/).filter(Boolean);
  if (t.length <= 1) return [name ?? "", ""];
  return [t.slice(0, -1).join(" "), t[t.length - 1]];
}

export default function TreePage() {
  const router = useRouter();
  const params = useParams<{ id: string }>();
  const treeId = params.id;
  const containerRef = useRef<HTMLDivElement>(null);

  const [people, setPeople] = useState<Person[]>([]);
  const [rels, setRels] = useState<Relationship[]>([]);
  const [events, setEvents] = useState<Event[]>([]);
  const [status, setStatus] = useState<"loading" | "empty" | "ready" | "error">("loading");
  const [focusId, setFocusId] = useState<string | null>(null);
  const [mode, setMode] = useState<Mode>("landscape");

  useEffect(() => {
    let cancelled = false;
    (async () => {
      const p = await api.GET("/api/v1/trees/{tree_id}/persons", {
        params: { path: { tree_id: treeId } },
      });
      if (p.response.status === 401) {
        router.push("/login");
        return;
      }
      const [r, e] = await Promise.all([
        api.GET("/api/v1/trees/{tree_id}/relationships", { params: { path: { tree_id: treeId } } }),
        api.GET("/api/v1/trees/{tree_id}/events", { params: { path: { tree_id: treeId } } }),
      ]);
      if (cancelled) return;
      const ppl = p.data ?? [];
      setPeople(ppl);
      setRels(r.data ?? []);
      setEvents(e.data ?? []);
      setFocusId((cur) => cur ?? ppl[0]?.id ?? null);
      setStatus(ppl.length ? "ready" : "empty");
    })().catch(() => !cancelled && setStatus("error"));
    return () => {
      cancelled = true;
    };
  }, [router, treeId]);

  const byId = useMemo(() => new Map(people.map((p) => [p.id, p])), [people]);
  const parentsOf = useCallback(
    (id: string) =>
      rels.filter((x) => x.type === "parent_child" && x.person_to_id === id).map((x) => x.person_from_id),
    [rels],
  );
  const childrenOf = useCallback(
    (id: string) =>
      rels.filter((x) => x.type === "parent_child" && x.person_from_id === id).map((x) => x.person_to_id),
    [rels],
  );
  const partnersOf = useCallback(
    (id: string) =>
      rels
        .filter((x) => x.type === "partnership" && (x.person_from_id === id || x.person_to_id === id))
        .map((x) => (x.person_from_id === id ? x.person_to_id : x.person_from_id)),
    [rels],
  );
  const years = useMemo(() => {
    const m = new Map<string, string>();
    for (const ev of events) {
      if (ev.person_id && ev.event_type === "birth" && !m.has(ev.person_id)) {
        const y = ev.date_start ? ev.date_start.slice(0, 4) : ev.date_value ?? "";
        if (y) m.set(ev.person_id, y);
      }
    }
    return m;
  }, [events]);
  const nameOf = useCallback((id: string) => byId.get(id)?.primary_name ?? "Unknown", [byId]);
  const yearOf = useCallback((id: string) => years.get(id) ?? "", [years]);

  // family-chart for landscape/portrait. Intentionally not keyed on focusId —
  // card clicks recenter via updateMainId without rebuilding the chart.
  useEffect(() => {
    if (status !== "ready" || mode === "fan" || !containerRef.current) return;
    let cancelled = false;
    (async () => {
      const data = people.map((pp) => {
        const [fn, ln] = splitName(pp.primary_name);
        return {
          id: pp.id,
          data: {
            "first name": fn || "Unnamed",
            "last name": ln,
            birthday: years.get(pp.id) ?? "",
            gender: pp.gender === "female" ? "F" : "M",
          },
          rels: { spouses: partnersOf(pp.id), parents: parentsOf(pp.id), children: childrenOf(pp.id) },
        };
      });
      const f3 = await import("family-chart");
      if (cancelled || !containerRef.current) return;
      containerRef.current.innerHTML = "";
      const chart = f3.createChart(containerRef.current, data);
      chart
        .setCardHtml()
        .setCardDisplay([["first name", "last name"], ["birthday"]])
        .setOnCardClick((_e: unknown, d: { data?: { id?: string } }) => {
          const id = d?.data?.id;
          if (id) {
            setFocusId(id);
            chart.updateMainId(id);
            chart.updateTree();
          }
        });
      if (mode === "portrait") chart.setOrientationVertical();
      else chart.setOrientationHorizontal();
      if (focusId) chart.updateMainId(focusId);
      chart.updateTree({ initial: true });
    })();
    return () => {
      cancelled = true;
    };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [status, mode, people, rels, events]);

  const ModeButton = ({ m, label }: { m: Mode; label: string }) => (
    <button
      onClick={() => setMode(m)}
      className={`rounded-md px-3 py-1.5 text-sm transition-colors ${
        mode === m ? "bg-bronze text-paper" : "text-[var(--muted)] hover:text-[var(--foreground)]"
      }`}
    >
      {label}
    </button>
  );

  return (
    <div className="space-y-4">
      <div className="flex flex-wrap items-center justify-between gap-3">
        <h1 className="text-2xl font-semibold">Tree</h1>
        <div className="flex items-center gap-3">
          <div className="flex items-center rounded-lg border border-[var(--border)] p-0.5">
            <ModeButton m="landscape" label="Landscape" />
            <ModeButton m="portrait" label="Portrait" />
            <ModeButton m="fan" label="Fan" />
          </div>
          {focusId && (
            <Link
              href={`/trees/${treeId}/persons/${focusId}`}
              className="text-sm text-bronze hover:underline"
            >
              Open {nameOf(focusId)} →
            </Link>
          )}
        </div>
      </div>

      {status === "empty" && (
        <p className="text-[var(--muted)]">No people yet — add some under People, or import a GEDCOM.</p>
      )}
      {status === "error" && <p className="text-[var(--muted)]">Could not render the tree.</p>}

      {status === "ready" && mode === "fan" && focusId ? (
        <div className="rounded-xl border border-[var(--border)] bg-[var(--surface)] p-4">
          <FanChart
            focusId={focusId}
            parentsOf={parentsOf}
            nameOf={nameOf}
            yearOf={yearOf}
            onSelect={setFocusId}
          />
        </div>
      ) : (
        <div
          ref={containerRef}
          className="f3 rounded-xl border border-[var(--border)]"
          style={{ width: "100%", height: "74vh", background: "var(--surface)" }}
        />
      )}

      <p className="text-sm text-[var(--muted)]">
        {mode === "fan"
          ? "Click an ancestor to recenter the fan."
          : "Drag to pan · scroll to zoom · click a person to recenter."}
      </p>
    </div>
  );
}