import React, { useEffect, useMemo, useRef, useState } from 'react';
import { Button } from './ui/button.js';
import api from '../auth/apiClient.js';

/* ---------- helpers ---------- */
const normalize = (s = '') =>
  s
    .toLowerCase()
    .replace(/\s*&\s*/g, ' and ')
    .replace(/[–—]/g, '-') // long dash → hyphen
    .replace(/\s+/g, ' ')
    .trim();

/* ---------- component ---------- */
const CareerSearch = ({ onCareerSelected, required, disabled: externallyDisabled = false }) => {
  const [suggestions, setSuggestions] = useState([]);  // [{title,soc_code,cip_codes,...}]
  const [searchInput, setSearchInput] = useState('');
  const [selectedObj, setSelectedObj] = useState(null);
  const [loading, setLoading] = useState(false);
  const abortRef = useRef(null);
  const lastMouseDownRef = useRef(0);
  const prevValueRef = useRef('');

  const computedDisabled = externallyDisabled || !!selectedObj;
  const listId = 'career-titles';

  // Debounced query to backend on input changes
  useEffect(() => {
    if (computedDisabled) return;

    const q = searchInput.trim();
    // Don’t fetch on empty string (keeps UX identical to your datalist flow)
    if (!q) {
      setSuggestions([]);
      return;
    }

    setLoading(true);

    // cancel previous in-flight
    if (abortRef.current) abortRef.current.abort();
    const ctrl = new AbortController();
    abortRef.current = ctrl;

    const timer = setTimeout(async () => {
      try {
        const { data } = await api.get('/api/careers/search', {
          params: { query: q, limit: 15 },
          signal: ctrl.signal
        });

        // De-dupe by normalized title (keep first)
        const map = new Map();
        for (const c of Array.isArray(data) ? data : []) {
          if (!c?.title || !c?.soc_code || !c?.cip_codes) continue;
          const key = normalize(c.title);
          if (!map.has(key)) {
            map.set(key, {
              title: c.title,
              soc_code: c.soc_code,
              cip_codes: c.cip_codes,
              limited_data: c.limited_data,
              ratings: c.ratings
            });
          }
        }
        setSuggestions([...map.values()]);
      } catch (err) {
        if (err?.name !== 'CanceledError' && err?.code !== 'ERR_CANCELED') {
          console.error('Career search failed:', err);
          setSuggestions([]);
        }
      } finally {
        setLoading(false);
      }
    }, 150); // debounce ~150ms (keeps typing snappy)

    return () => {
      clearTimeout(timer);
      ctrl.abort();
    };
  }, [searchInput, computedDisabled]);

  // Handle Enter → commit first startsWith match (then datalist shows exact)
const handleKeyDown = (e) => {
  if (computedDisabled || e.key !== 'Enter') return;

  const n = normalize(searchInput);
  const exact  = suggestions.find(o => normalize(o.title) === n);
  const firstP = suggestions.find(o => normalize(o.title).startsWith(n));
  const first  = exact || firstP || suggestions[0];

  if (!first) return;

  const payload = { ...first, cip_code: first.cip_codes };
  setSearchInput(first.title);
  setSelectedObj(payload);
  onCareerSelected?.(payload);
  e.preventDefault();
};


  const reset = () => {
    setSelectedObj(null);
    setSearchInput('');
    setSuggestions([]);
  };

  return (
    <div className="mb-4">
      <label className="block font-medium mb-1">
        Search for Career <span className="text-red-600">*</span>
      </label>

      <div className="relative">
        <input
          type="text"
          list={listId}
          value={searchInput}
          required={required}
          disabled={computedDisabled}
          onMouseDown={() => { lastMouseDownRef.current = Date.now(); }}
          onChange={async (e) => {
            const val = e.target.value;
            setSearchInput(val);
            if (computedDisabled) return;

            const exact = suggestions.find(o => normalize(o.title) === normalize(val));

            // Heuristic: datalist pick usually replaces many characters at once.
            const prev = prevValueRef.current || '';
            const bigJump = Math.abs(val.length - prev.length) > 1;

            // Also still catch Chromium’s signal when present.
            const it = e?.nativeEvent?.inputType;
            const replacement = it === 'insertReplacementText';

            if (exact && (bigJump || replacement)) {
              const payload = { ...exact, cip_code: exact.cip_codes }; // full SOC preserved
              setSelectedObj(payload);
              onCareerSelected?.(payload);
            }

            // update after processing to get a clean delta next time
            prevValueRef.current = val;
          }}

          onKeyDown={handleKeyDown}
          onBlur={async () => {
            if (computedDisabled) return;
            const exact = suggestions.find(o => normalize(o.title) === normalize(searchInput));
            if (!exact) return;
            const payload = { ...exact, cip_code: exact.cip_codes };
            setSelectedObj(payload);
            onCareerSelected?.(payload);
          }}
          className={`w-full border rounded p-2 ${computedDisabled ? 'bg-gray-100 cursor-not-allowed opacity-60' : ''}`}
          placeholder="Start typing a career..."
          autoComplete="off"
        />


        {!computedDisabled && (
          <datalist id={listId}>
            {suggestions.map((o) => (
              <option key={`${o.soc_code}:${o.title}`} value={o.title} />
            ))}
          </datalist>
        )}

        {loading && !computedDisabled && (
          <div className="absolute right-2 top-2 text-xs text-gray-500">loading…</div>
        )}
      </div>

      {!selectedObj && (
        <p className="mt-2 text-sm text-blue-700">
          Please pick from the dropdown when performing search. Our database is very comprehensive but can’t
          accommodate every job title—choose the closest match to what you’re searching for.
        </p>
      )}

      {selectedObj && !externallyDisabled && (
        <button
          type="button"
          onClick={reset}
          className="text-blue-600 underline text-sm mt-1"
        >
          Change
        </button>
      )}
    </div>
  );
};

export default CareerSearch;