"use client";

import { Handle, Position, type Node, type NodeProps } from "@xyflow/react";
import { Building2, ChevronDown, Plus, UserRound } from "lucide-react";
import Link from "next/link";
import { memo } from "react";
import { Avatar } from "@/components/ui/Avatar";
import { NODE_DIMENSIONS } from "./graphLayout";
import type { ChartNode, ChartNodeKind } from "./types";

export type OrgChartNodeData = {
  chartNode: ChartNode;
  expanded: boolean;
  hasChildren: boolean;
  childCount: number;
  onToggle: (id: string) => void;
};

export type OrgChartRFNode = Node<OrgChartNodeData, "orgNode">;

// One accent colour per node kind, carried by a left stripe. It is what makes
// the four kinds separable at a glance when the chart is zoomed out far
// enough that the text has stopped being legible.
const KIND_ACCENT: Record<ChartNodeKind, string> = {
  person: "bg-brand-500",
  role: "bg-purple-text",
  group: "bg-ink-muted",
  vacancy: "bg-brand-200",
};

const KIND_SHELL: Record<ChartNodeKind, string> = {
  person: "border-border bg-white",
  role: "border-border bg-white",
  group: "border-border-subtle bg-surface",
  vacancy: "border-dashed border-brand-200 bg-brand-50",
};

// React Flow re-renders node components on every pan/zoom frame — memo is
// required, not just tidy, to keep that smooth at a few hundred nodes.
export const OrgChartNode = memo(function OrgChartNode({ id, data }: NodeProps<OrgChartRFNode>) {
  const { chartNode, expanded, hasChildren, childCount, onToggle } = data;
  const { kind, label, sublabel, avatar, href, vacant, totalReports, absent, coveredBy, coveringFor } = chartNode;
  const isMatch = chartNode.matched ?? false;
  const { width, height } = NODE_DIMENSIONS[kind];

  const content = (
    <>
      {kind === "person" && avatar ? (
        <Avatar firstName={avatar.firstName} lastName={avatar.lastName} size="sm" />
      ) : kind === "vacancy" ? (
        <span className="flex h-7 w-7 shrink-0 items-center justify-center rounded-full border border-dashed border-brand-200 text-brand-500">
          <Plus className="h-3.5 w-3.5" />
        </span>
      ) : kind === "role" ? (
        <span className="flex h-7 w-7 shrink-0 items-center justify-center rounded-full bg-purple-bg text-purple-text">
          <UserRound className="h-3.5 w-3.5" />
        </span>
      ) : (
        <span className="flex h-6 w-6 shrink-0 items-center justify-center rounded-full bg-white text-ink-muted">
          <Building2 className="h-3.5 w-3.5" />
        </span>
      )}

      <span className="flex min-w-0 flex-1 flex-col">
        <span title={label} className="truncate text-[13px] font-bold leading-tight text-ink">
          {label}
        </span>
        {sublabel && (
          <span
            title={sublabel}
            className={`truncate text-[11px] leading-tight ${vacant ? "font-semibold text-warning-text" : "text-ink-muted"}`}
          >
            {sublabel}
          </span>
        )}
        {/* The stand-in replaces the report count rather than crowding in
            next to it: on a card this size the arrangement is the more
            important of the two, and it only appears while one is in force. */}
        {absent ? (
          <span className="mt-0.5 truncate text-[10px] font-semibold text-warning-text">
            Abwesend{coveredBy ? ` · Vertretung: ${coveredBy}` : ""}
          </span>
        ) : coveringFor ? (
          <span className="mt-0.5 truncate text-[10px] font-semibold text-info-text">Vertretung für {coveringFor}</span>
        ) : (
          totalReports !== undefined &&
          totalReports > 0 && (
            <span className="mt-0.5 text-[10px] font-semibold uppercase tracking-wide text-ink-muted">
              {childCount} direkt · {totalReports} gesamt
            </span>
          )
        )}
      </span>
    </>
  );

  return (
    <div
      style={{ width, height }}
      className={`group relative flex items-center overflow-visible rounded-lg border shadow-sm transition-shadow hover:shadow-md ${
        KIND_SHELL[kind]
      } ${isMatch ? "ring-2 ring-brand-500 ring-offset-1" : ""}`}
    >
      <Handle type="target" position={Position.Top} isConnectable={false} className="!invisible" />

      {/* Accent stripe, inset so it follows the card's rounded corner. */}
      <span className={`absolute inset-y-1.5 left-0 w-1 rounded-r ${KIND_ACCENT[kind]}`} />

      {href ? (
        <Link href={href} className="nodrag nopan flex min-w-0 flex-1 items-center gap-2.5 py-2 pl-3.5 pr-3">
          {content}
        </Link>
      ) : (
        <div className="flex min-w-0 flex-1 items-center gap-2.5 py-2 pl-3.5 pr-3">{content}</div>
      )}

      {/* Overhangs the bottom edge, sitting on the connector to its children —
          the conventional org-chart affordance, and a 28px touch target. */}
      {hasChildren && (
        <button
          type="button"
          onClick={() => onToggle(id)}
          aria-expanded={expanded}
          aria-label={expanded ? `${label} zuklappen` : `${label} aufklappen (${childCount})`}
          className="nodrag nopan absolute -bottom-3.5 left-1/2 z-10 flex h-7 min-w-7 -translate-x-1/2 items-center justify-center rounded-full border border-border bg-white px-1.5 text-[11px] font-bold text-ink-body shadow-sm transition-colors hover:border-brand-500 hover:bg-brand-500 hover:text-white"
        >
          {expanded ? <ChevronDown className="h-3.5 w-3.5" /> : childCount}
        </button>
      )}

      <Handle type="source" position={Position.Bottom} isConnectable={false} className="!invisible" />
    </div>
  );
});
