"use client";

import { useEffect, useMemo, useState } from "react";
import L from "leaflet";
import { MapContainer, Marker, Popup, TileLayer, Tooltip, Circle, useMap, useMapEvents } from "react-leaflet";
import { useTheme } from "next-themes";
import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
import { Badge } from "@/components/ui/badge";
import { Button } from "@/components/ui/button";
import { Input } from "@/components/ui/input";
import { Maximize2, Mail, MapPin, Minimize2, Move, Phone, RefreshCw, Search, Tag } from "lucide-react";
import { toast } from "sonner";
import { getMappableSuppliers } from "@/lib/pb-helpers";
import getPocketBase from "@/lib/pocketbase";
import type { Supplier } from "@/lib/types";
import {
  buildClusters,
  CLUSTER_PALETTE,
  clusterDistanceForZoom,
  parseCoordinates,
  type Cluster,
} from "@/lib/geo";
import { clusterBubble, pinMarker } from "@/components/leaflet-markers";

type SupplierPoint = Supplier & {
  lat: number;
  lng: number;
};

type SupplierCluster = Cluster<SupplierPoint>;

const DEFAULT_CENTER: [number, number] = [-26.2041, 28.0473];
const CLUSTER_ZOOM_BREAKPOINT = 12;
const LABEL_ZOOM_BREAKPOINT = 12;
/**
 * Max number of permanent supplier-name labels visible on the map at
 * once. Picked by distance to viewport centre — keeps the DOM light
 * when zoomed in over a dense cluster of pins.
 */
const LABEL_LIMIT = 24;
/** Stable empty Set so consumers can `has()` without re-creating it. */
const EMPTY_LABELED_IDS = new Set<string>();
const LIGHT_TILE_URL = "https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png";
const DARK_TILE_URL = "https://{s}.basemaps.cartocdn.com/dark_all/{z}/{x}/{y}{r}.png";
const LIGHT_TILE_ATTRIBUTION = '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a>';
const DARK_TILE_ATTRIBUTION = '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> &copy; <a href="https://carto.com/attributions">CARTO</a>';

function MapWatcher({
  isFullscreen,
  onZoomChange,
  onViewportChange,
}: {
  isFullscreen: boolean;
  onZoomChange: (zoom: number) => void;
  onViewportChange: (viewport: { center: [number, number]; zoom: number }) => void;
}) {
  const map = useMap();

  useEffect(() => {
    window.setTimeout(() => map.invalidateSize(), 180);
  }, [isFullscreen, map]);

  useMapEvents({
    zoomend: (event) => {
      const target = event.target;
      const zoom = target.getZoom();
      const center = target.getCenter();
      onZoomChange(zoom);
      onViewportChange({ center: [center.lat, center.lng], zoom });
    },
    moveend: (event) => {
      const target = event.target;
      const center = target.getCenter();
      onViewportChange({ center: [center.lat, center.lng], zoom: target.getZoom() });
    },
  });

  return null;
}

function ClusterMarker({ cluster }: { cluster: SupplierCluster }) {
  const map = useMap();
  const count = cluster.items.length;

  if (count === 1) {
    const supplier = cluster.items[0];
    return (
      <Marker position={[supplier.lat, supplier.lng]} icon={pinMarker(cluster.color, "")}>
        <Popup>
          <SupplierPopup supplier={supplier} editMode={false} />
        </Popup>
      </Marker>
    );
  }

  return (
    <Marker
      position={[cluster.center[0], cluster.center[1]]}
      icon={clusterBubble(cluster.color, count)}
      eventHandlers={{
        click: () => {
          map.closePopup();
          map.flyTo([cluster.center[0], cluster.center[1]], Math.min(map.getZoom() + 2, CLUSTER_ZOOM_BREAKPOINT), { duration: 0.4 });
        },
      }}
    />
  );
}

function SupplierPopup({ supplier, editMode }: { supplier: SupplierPoint; editMode: boolean }) {
  return (
    <div className="space-y-1 text-sm">
      <p className="font-semibold">{supplier.suppliername || "Unnamed supplier"}</p>
      {supplier.supplieraddress && <p>{supplier.supplieraddress}</p>}
      {supplier.suppliernumber && <p>Phone: {supplier.suppliernumber}</p>}
      {supplier.email && <p>Email: {supplier.email}</p>}
      {supplier.supply_tags && <p>Tags: {supplier.supply_tags}</p>}
      {editMode && (
        <p className="pt-1 text-xs font-medium text-primary">
          Drag this marker to correct its saved location.
        </p>
      )}
    </div>
  );
}

export function SupplierMap() {
  const { resolvedTheme } = useTheme();
  const [suppliers, setSuppliers] = useState<Supplier[]>([]);
  const [loading, setLoading] = useState(true);
  const [search, setSearch] = useState("");
  const [zoom, setZoom] = useState(10);
  const [viewport, setViewport] = useState<{ center: [number, number]; zoom: number } | null>(null);
  const [isFullscreen, setIsFullscreen] = useState(false);
  const [editMode, setEditMode] = useState(false);
  const isDarkMap = resolvedTheme === "dark";

  const fetchSuppliers = async () => {
    setLoading(true);
    try {
      setSuppliers(await getMappableSuppliers());
    } catch (err) {
      toast.error(err instanceof Error ? err.message : "Failed to load suppliers");
    } finally {
      setLoading(false);
    }
  };

  useEffect(() => {
    fetchSuppliers();
  }, []);

  const saveSupplierLocation = async (supplier: SupplierPoint, lat: number, lng: number) => {
    const coordinates = `${lat.toFixed(6)}, ${lng.toFixed(6)}`;

    setSuppliers((current) =>
      current.map((item) => (item.id === supplier.id ? { ...item, coordinates } : item))
    );

    try {
      const pb = getPocketBase();
      await pb.collection("suppliers").update(supplier.id, { coordinates });
      toast.success(`Updated ${supplier.suppliername || "supplier"} location`);
    } catch (err) {
      setSuppliers((current) =>
        current.map((item) => (item.id === supplier.id ? { ...item, coordinates: supplier.coordinates } : item))
      );
      toast.error(err instanceof Error ? err.message : "Failed to update supplier location");
    }
  };

  const { mapped, missing } = useMemo(() => {
    const filtered = suppliers.filter((supplier) => {
      const query = search.trim().toLowerCase();
      if (!query) return true;
      return [supplier.suppliername, supplier.supplieraddress, supplier.supply_tags]
        .some((value) => value?.toLowerCase().includes(query));
    });

    const supplierPoints: SupplierPoint[] = [];
    const missingCoordinates: Supplier[] = [];

    for (const supplier of filtered) {
      const coordinates = parseCoordinates(supplier.coordinates);
      if (!coordinates) {
        missingCoordinates.push(supplier);
        continue;
      }

      supplierPoints.push({
        ...supplier,
        lat: coordinates[0],
        lng: coordinates[1],
      });
    }

    return { mapped: supplierPoints, missing: missingCoordinates };
  }, [search, suppliers]);

  const clusterDistanceKm = clusterDistanceForZoom(zoom);
  // `clusterDistanceKm` only changes when zoom crosses one of
  // {7, 9, 11} (see clusterDistanceForZoom). Dep'ing on the bucket
  // value — not on zoom — keeps `buildClusters` from re-running on
  // every wheel tick. If you change the cluster distance function,
  // keep this bucketed.
  const clusters = useMemo(() => buildClusters(mapped, clusterDistanceKm), [clusterDistanceKm, mapped]);
  const showIndividualSuppliers = zoom >= CLUSTER_ZOOM_BREAKPOINT;
  const showLabels = zoom >= LABEL_ZOOM_BREAKPOINT;
  const mapCenter: [number, number] = mapped.length
    ? [
        mapped.reduce((sum, supplier) => sum + supplier.lat, 0) / mapped.length,
        mapped.reduce((sum, supplier) => sum + supplier.lng, 0) / mapped.length,
      ]
    : DEFAULT_CENTER;

  const clusterBySupplierId = useMemo(() => {
    const m = new Map<string, SupplierCluster>();
    for (const cluster of clusters) {
      for (const supplier of cluster.items) {
        m.set(supplier.id, cluster);
      }
    }
    return m;
  }, [clusters]);

  /**
   * IDs of the suppliers that should render a permanent name label
   * at the current zoom. Top LABEL_LIMIT by squared distance to the
   * viewport centre — cheap, no sqrt, and "centre of viewport" is a
   * good enough proxy for "what the user is actually looking at".
   */
  const labeledIds = useMemo(() => {
    if (!showLabels || !viewport) return EMPTY_LABELED_IDS;
    const [cLat, cLng] = viewport.center;
    const ranked = mapped
      .map((supplier) => ({
        id: supplier.id,
        d: (supplier.lat - cLat) ** 2 + (supplier.lng - cLng) ** 2,
      }))
      .sort((a, b) => a.d - b.d)
      .slice(0, LABEL_LIMIT);
    return new Set(ranked.map((entry) => entry.id));
  }, [mapped, showLabels, viewport]);

  return (
    <div className="space-y-5">
      <div className="grid gap-4 md:grid-cols-3">
        <Card className="border-primary/10">
          <CardHeader className="pb-2">
            <CardTitle className="text-sm text-muted-foreground">Mapped Suppliers</CardTitle>
          </CardHeader>
          <CardContent>
            <p className="text-3xl font-bold">{mapped.length}</p>
            <p className="text-xs text-muted-foreground">With usable coordinates</p>
          </CardContent>
        </Card>
        <Card className="border-primary/10">
          <CardHeader className="pb-2">
            <CardTitle className="text-sm text-muted-foreground">Proximity Groups</CardTitle>
          </CardHeader>
          <CardContent>
            <p className="text-3xl font-bold">{clusters.length}</p>
            <p className="text-xs text-muted-foreground">Grouped within {clusterDistanceKm}km at this zoom</p>
          </CardContent>
        </Card>
        <Card className="border-primary/10">
          <CardHeader className="pb-2">
            <CardTitle className="text-sm text-muted-foreground">Needs Coordinates</CardTitle>
          </CardHeader>
          <CardContent>
            <p className="text-3xl font-bold">{missing.length}</p>
            <p className="text-xs text-muted-foreground">Supplier records to update</p>
          </CardContent>
        </Card>
      </div>

      <div className="flex flex-col gap-3 sm:flex-row sm:items-center sm:justify-between">
        <div className="relative w-full sm:max-w-sm">
          <Search className="absolute left-3 top-1/2 h-4 w-4 -translate-y-1/2 text-muted-foreground" />
          <Input
            value={search}
            onChange={(event) => setSearch(event.target.value)}
            placeholder="Search suppliers, tags, address..."
            className="pl-9"
          />
        </div>
        <div className="flex flex-wrap gap-2">
          <Button
            variant={editMode ? "default" : "outline"}
            onClick={() => setEditMode((enabled) => !enabled)}
          >
            <Move className="mr-2 h-4 w-4" />
            {editMode ? "Done Editing" : "Edit Locations"}
          </Button>
          <Button variant="outline" onClick={fetchSuppliers} disabled={loading}>
            <RefreshCw className={`mr-2 h-4 w-4 ${loading ? "animate-spin" : ""}`} />
            Refresh
          </Button>
        </div>
      </div>

      <div className="grid items-start gap-5 xl:grid-cols-[minmax(0,1fr)_360px]">
        <Card className={`overflow-hidden border-primary/10 py-0 ${isFullscreen ? "fixed inset-0 z-[45] rounded-none border-0" : "relative z-0"}`}>
          <div className={`${isFullscreen ? "h-dvh min-h-0" : "h-[68vh] min-h-[520px]"} relative`}>
            <div className="absolute right-3 top-3 z-[30] flex flex-col gap-2 sm:flex-row">
              {editMode && (
                <div className="rounded-full border bg-background/95 px-3 py-2 text-xs font-medium shadow-sm backdrop-blur">
                  Drag pins to save locations
                </div>
              )}
              <Button
                type="button"
                variant="secondary"
                size="sm"
                className="h-9 rounded-full bg-background/95 shadow-sm backdrop-blur"
                onClick={() => setIsFullscreen((fullscreen) => !fullscreen)}
              >
                {isFullscreen ? <Minimize2 className="mr-2 h-4 w-4" /> : <Maximize2 className="mr-2 h-4 w-4" />}
                {isFullscreen ? "Exit" : "Fullscreen"}
              </Button>
            </div>
            <MapContainer center={mapCenter} zoom={mapped.length ? 10 : 6} scrollWheelZoom className="h-full w-full">
              <MapWatcher
                isFullscreen={isFullscreen}
                onZoomChange={setZoom}
                onViewportChange={setViewport}
              />
              <TileLayer
                key={isDarkMap ? "dark" : "light"}
                attribution={isDarkMap ? DARK_TILE_ATTRIBUTION : LIGHT_TILE_ATTRIBUTION}
                url={isDarkMap ? DARK_TILE_URL : LIGHT_TILE_URL}
              />
              {!showIndividualSuppliers &&
                clusters.map((cluster) => (
                  <ClusterMarker key={cluster.id} cluster={cluster} />
                ))}
              {showIndividualSuppliers &&
                clusters.map((cluster) => (
                  <Circle
                    key={cluster.id}
                    center={[cluster.center[0], cluster.center[1]]}
                    radius={clusterDistanceKm * 1000}
                    pathOptions={{ color: cluster.color, fillColor: cluster.color, fillOpacity: 0.05, weight: 1 }}
                  />
                ))}
              {showIndividualSuppliers &&
                mapped.map((supplier) => {
                  const cluster = clusterBySupplierId.get(supplier.id);
                  const label = cluster ? String(cluster.items.findIndex((item) => item.id === supplier.id) + 1) : "";
                  return (
                    <Marker
                      key={supplier.id}
                      position={[supplier.lat, supplier.lng]}
                      icon={pinMarker(cluster?.color || CLUSTER_PALETTE[0], label)}
                      draggable={editMode}
                      eventHandlers={{
                        dragend: (event) => {
                          const marker = event.target as L.Marker;
                          const position = marker.getLatLng();
                          void saveSupplierLocation(supplier, position.lat, position.lng);
                        },
                      }}
                    >
                      {showLabels && labeledIds.has(supplier.id) && (
                        <Tooltip direction="top" offset={[0, -12]} permanent className="supplier-map-label">
                          {supplier.suppliername || "Unnamed supplier"}
                        </Tooltip>
                      )}
                      <Popup>
                        <SupplierPopup supplier={supplier} editMode={editMode} />
                      </Popup>
                    </Marker>
                  );
                })}
            </MapContainer>
          </div>
        </Card>

        <div className="space-y-4">
          <Card className="border-primary/10">
            <CardHeader>
              <CardTitle className="flex items-center gap-2 text-base">
                <MapPin className="h-4 w-4 text-primary" />
                Proximity Groups
              </CardTitle>
            </CardHeader>
            <CardContent className="max-h-[360px] space-y-3 overflow-auto">
              {clusters.length === 0 ? (
                <p className="text-sm text-muted-foreground">No mapped suppliers yet.</p>
              ) : (
                clusters.map((cluster, index) => (
                  <div key={cluster.id} className="rounded-xl border p-3">
                    <div className="mb-2 flex items-center justify-between">
                      <div className="flex items-center gap-2">
                        <span className="h-3 w-3 rounded-full" style={{ backgroundColor: cluster.color }} />
                        <p className="text-sm font-semibold">Group {index + 1}</p>
                      </div>
                      <Badge variant="outline">{cluster.items.length} supplier{cluster.items.length === 1 ? "" : "s"}</Badge>
                    </div>
                    <div className="space-y-2">
                      {cluster.items.map((supplier, supplierIndex) => (
                        <div key={supplier.id} className="text-sm">
                          <p className="font-medium">{supplierIndex + 1}. {supplier.suppliername || "Unnamed supplier"}</p>
                          {supplier.supplieraddress && (
                            <p className="text-xs text-muted-foreground">{supplier.supplieraddress}</p>
                          )}
                        </div>
                      ))}
                    </div>
                  </div>
                ))
              )}
            </CardContent>
          </Card>

          <Card className="border-primary/10">
            <CardHeader>
              <CardTitle className="text-base">Missing Coordinates</CardTitle>
            </CardHeader>
            <CardContent className="max-h-[300px] space-y-3 overflow-auto">
              {missing.length === 0 ? (
                <p className="text-sm text-muted-foreground">All visible suppliers have coordinates.</p>
              ) : (
                missing.map((supplier) => (
                  <div key={supplier.id} className="rounded-xl border p-3">
                    <p className="font-medium">{supplier.suppliername || "Unnamed supplier"}</p>
                    {supplier.supplieraddress && <p className="mt-1 text-xs text-muted-foreground">{supplier.supplieraddress}</p>}
                    <div className="mt-2 flex flex-wrap gap-2 text-xs text-muted-foreground">
                      {supplier.suppliernumber && <span className="inline-flex items-center gap-1"><Phone className="h-3 w-3" />{supplier.suppliernumber}</span>}
                      {supplier.email && <span className="inline-flex items-center gap-1"><Mail className="h-3 w-3" />{supplier.email}</span>}
                      {supplier.supply_tags && <span className="inline-flex items-center gap-1"><Tag className="h-3 w-3" />{supplier.supply_tags}</span>}
                    </div>
                  </div>
                ))
              )}
            </CardContent>
          </Card>
        </div>
      </div>
    </div>
  );
}