// src/components/ui/MultiSelect.jsx
// Multi-select dropdown — same visual language as Select.jsx (floating portal
// menu, .select-* trigger styling) but with checkbox rows so multiple options
// can be chosen at once. Trigger shows "All", a single label, or "N selected".
//
// Props:
//   options     — Array<{ value: string, label: ReactNode }>
//   value       — Array<string> — currently selected values (empty = "all")
//   onChange    — (nextValues: string[]) => void
//   placeholder — shown when value is empty (default: 'All')
//   disabled    — boolean
//   className   — extra classes on the trigger button
//   id          — forwarded for label association

import { useState, useRef, useEffect } from 'react'
import { createPortal } from 'react-dom'
import { computeFloatingMenuPosition } from '@/lib/floatingMenuPosition'

export default function MultiSelect({
  options = [],
  value = [],
  onChange,
  placeholder = 'All',
  disabled = false,
  className = '',
  id,
  ...props
}) {
  const [open, setOpen]       = useState(false)
  const [menuPos, setMenuPos] = useState({ top: 0, left: 0, width: 0, maxHeight: 280 })
  const triggerRef            = useRef(null)
  const menuRef                = useRef(null)

  useEffect(() => {
    if (!open) return
    function close(e) {
      if (triggerRef.current?.contains(e.target)) return
      if (menuRef.current?.contains(e.target)) return
      setOpen(false)
    }
    function closeOnScroll(e) {
      if (menuRef.current?.contains(e.target)) return
      if (triggerRef.current?.contains(e.target)) return
      setOpen(false)
    }
    document.addEventListener('mousedown', close)
    document.addEventListener('scroll', closeOnScroll, true)
    return () => {
      document.removeEventListener('mousedown', close)
      document.removeEventListener('scroll', closeOnScroll, true)
    }
  }, [open])

  function openMenu() {
    if (disabled) return
    if (triggerRef.current) {
      setMenuPos(computeFloatingMenuPosition(triggerRef.current.getBoundingClientRect()))
    }
    setOpen(true)
  }

  function handleToggle() {
    if (open) setOpen(false)
    else openMenu()
  }

  function toggleValue(v) {
    const next = value.includes(v) ? value.filter((x) => x !== v) : [...value, v]
    onChange?.(next)
  }

  const label = value.length === 0
    ? placeholder
    : value.length === 1
      ? (options.find((o) => o.value === value[0])?.label ?? value[0])
      : `${value.length} selected`

  const menu = open && createPortal(
    <div
      ref={menuRef}
      className="select-menu multi-select-menu"
      style={{ top: menuPos.top, bottom: menuPos.bottom, left: menuPos.left, width: menuPos.width, maxHeight: menuPos.maxHeight }}
      role="listbox"
      aria-multiselectable="true"
      aria-label="Options"
    >
      {value.length > 0 && (
        <div
          className="select-option multi-select-clear"
          onMouseDown={(e) => { e.preventDefault(); onChange?.([]) }}
        >
          <span>Clear selection</span>
        </div>
      )}
      {options.map((opt) => {
        const checked = value.includes(opt.value)
        return (
          <div
            key={opt.value}
            role="option"
            aria-selected={checked}
            className={['select-option', checked ? 'select-option-selected' : ''].filter(Boolean).join(' ')}
            onMouseDown={(e) => { e.preventDefault(); toggleValue(opt.value) }}
          >
            <input
              type="checkbox"
              checked={checked}
              readOnly
              tabIndex={-1}
              style={{ accentColor: 'var(--color-primary)', flexShrink: 0, pointerEvents: 'none' }}
            />
            <span>{opt.label}</span>
          </div>
        )
      })}
    </div>,
    document.body
  )

  return (
    <>
      <button
        ref={triggerRef}
        type="button"
        id={id}
        disabled={disabled}
        onClick={handleToggle}
        className={[
          'input',
          'select-trigger',
          open ? 'select-trigger-open' : '',
          className,
        ].filter(Boolean).join(' ')}
        aria-haspopup="listbox"
        aria-expanded={open}
        {...props}
      >
        <span className={value.length ? 'select-value' : 'select-placeholder'}>
          {label}
        </span>
        <span className="select-chevron" aria-hidden="true">
          <svg width="16" height="16" viewBox="0 0 16 16" fill="none">
            <path d="M4 6l4 4 4-4" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round" strokeLinejoin="round" />
          </svg>
        </span>
      </button>
      {menu}
    </>
  )
}