import React, { useMemo, useState } from 'react';
import { toast } from '@/components/ds';
import { useWorkerProfiles } from '@/lib/krowHooks';
import { AdminPage } from '@/components/admin/PageShell';
import { UiTreeRenderer } from '@/components/ui-tree/UiTreeRenderer';
import { useUiEditing } from '@/components/ui-tree/UiEditingProvider';
import { UiEditor } from '@/components/ui-editor/UiEditor';
import { composePage } from '@/lib/ui/composition';
import { SORTS } from '@/pages/admin/talent-pool/nodes';
import '@/components/ui-tree/nodeTypes';
import '@/pages/admin/talent-pool/nodes';

/**
 * Admin Talent Pool — talent intelligence, not a card gallery.
 */


const BANDS = {
  all: () => true,
  elite: (s) => s >= 90,
  excellent: (s) => s >= 75 && s < 90,
  solid: (s) => s >= 60 && s < 75,
  building: (s) => s > 0 && s < 60,
  unscored: (s) => !s,
};


export default function AdminTalentPool() {
  const { data: profiles = [], isLoading } = useWorkerProfiles();

  const [search, setSearch] = useState('');
  const [skill, setSkill] = useState('all');
  const [experience, setExperience] = useState('all');
  const [location, setLocation] = useState('all');
  const [band, setBand] = useState('all');
  const [availability, setAvailability] = useState('all');
  const [sort, setSort] = useState('score');
  const [saved, setSaved] = useState([]);

  const skills = useMemo(
    () => [...new Set(profiles.flatMap((p) => p.skills || []))].sort(),
    [profiles]
  );
  const locations = useMemo(
    () => [...new Set(profiles.map((p) => p.address).filter(Boolean))].sort(),
    [profiles]
  );
  const availabilities = useMemo(
    () => [...new Set(profiles.flatMap((p) => p.availability || []))].sort(),
    [profiles]
  );

  const filtered = useMemo(() => {
    const q = search.toLowerCase();
    return profiles
      .filter((p) => {
        if (q && !`${p.full_name} ${p.email} ${p.desired_position} ${p.current_position} ${(p.skills || []).join(' ')}`.toLowerCase().includes(q)) return false;
        if (skill !== 'all' && !(p.skills || []).includes(skill)) return false;
        if (location !== 'all' && p.address !== location) return false;
        if (availability !== 'all' && !(p.availability || []).includes(availability)) return false;
        if (!BANDS[band](p.krow_score || 0)) return false;
        if (experience === '5plus' && (p.experience_years || 0) < 5) return false;
        if (experience === '2to5' && ((p.experience_years || 0) < 2 || (p.experience_years || 0) >= 5)) return false;
        if (experience === 'under2' && (p.experience_years || 0) >= 2) return false;
        return true;
      })
      .sort(SORTS[sort].compare);
  }, [profiles, search, skill, experience, location, band, availability, sort]);

  const isFiltered = Boolean(search) || [skill, experience, location, band, availability].some((v) => v !== 'all');
  const clearFilters = () => {
    setSearch(''); setSkill('all'); setExperience('all'); setLocation('all'); setBand('all'); setAvailability('all');
  };

  const segments = useMemo(() => {
    const getBandMembers = (min, max) => profiles.filter((p) => {
      const s = p.krow_score || 0;
      return s >= min && (max == null || s < max);
    });
    return [
      { label: 'Elite', hint: '90+', members: getBandMembers(90), tone: 'brand' },
      { label: 'Excellent', hint: '75–89', members: getBandMembers(75, 90), tone: 'success' },
      { label: 'Solid', hint: '60–74', members: getBandMembers(60, 75), tone: 'default' },
      { label: 'Building', hint: 'under 60', members: getBandMembers(1, 60), tone: 'warning' },
      { label: 'Unscored', hint: 'no score', members: profiles.filter((p) => !(p.krow_score > 0)), tone: 'risk' },
    ].map((s) => ({
      ...s,
      count: s.members.length,
      available: s.members.filter((p) => (p.availability || []).length > 0).length,
      avgExperience: (() => {
        /* 0 years is "not stated", not "first year" — the cards that show it
           gate on experience_years > 0, so the average is over the same set. */
        const stated = s.members.filter((p) => (p.experience_years || 0) > 0);
        return stated.length
          ? Math.round(stated.reduce((sum, p) => sum + p.experience_years, 0) / stated.length)
          : 0;
      })(),
    }));
  }, [profiles]);

  const toggleSave = (id, name) => {
    setSaved((prev) => {
      const next = prev.includes(id) ? prev.filter((x) => x !== id) : [...prev, id];
      toast.success(prev.includes(id) ? `${name} removed from saved` : `${name} saved`);
      return next;
    });
  };

  const context = useMemo(() => ({
    profiles, segments, filtered, isLoading, isFiltered, clearFilters, saved, toggleSave,
    search, setSearch, skill, setSkill, experience, setExperience, location, setLocation,
    band, setBand, availability, setAvailability, sort, setSort,
    skills, locations, availabilities,
  }), [
    profiles, segments, filtered, isLoading, isFiltered, saved,
    search, skill, experience, location, band, availability, sort, skills, locations, availabilities,
  ]);

  return (
    <AdminPage
      title="Talent Pool"
      subtitle="Discover and manage high-potential talent for future hiring."
    >
      <UiEditor />
      <TalentPoolComposition context={context} />
    </AdminPage>
  );
}

/** The composed page. */
function TalentPoolComposition({ context }) {
  const editing = useUiEditing();
  const tree = editing?.tree || composePage('talent-pool').tree;
  return <UiTreeRenderer nodes={tree} context={context} />;
}