// TODO: P2-F15 — Replace hardcoded SORT_FIELDS with shared constant
/**
 * SmartSuite-style Sort Panel for Mail.
 * Multi-field sorting with priority order.
 * Based on contacts/SortPanel.tsx
 */

import React, { useState, useRef, useEffect } from 'react';
import { ArrowUpDown, Plus, X, ChevronUp, ChevronDown } from 'lucide-react';

type FieldType = 'text' | 'number' | 'date';

interface SortFieldDef {
  key: string;
  label: string;
  type: FieldType;
  group?: string;
}

const SORT_FIELDS: SortFieldDef[] = [
  { key: 'date', label: 'Datum', type: 'date', group: 'Allgemein' },
  { key: 'from', label: 'Absender', type: 'text', group: 'Allgemein' },
  { key: 'subject', label: 'Betreff', type: 'text', group: 'Allgemein' },
  { key: 'to', label: 'Empfänger', type: 'text', group: 'Allgemein' },
  { key: 'size', label: 'Größe', type: 'number', group: 'Metadaten' },
  { key: 'is_read', label: 'Gelesen', type: 'text', group: 'Metadaten' },
  { key: 'is_flagged', label: 'Markiert', type: 'text', group: 'Metadaten' },
];

export interface SortCondition {
  id: string;
  field: string;
  direction: 'asc' | 'desc';
}

export interface SortState {
  conditions: SortCondition[];
}

export const emptySortState: SortState = {
  conditions: [],
};

function getFieldValue(mail: any, field: string): any {
  return (mail as any)[field];
}

function compareValues(a: any, b: any, fieldType: FieldType): number {
  if (a == null && b == null) return 0;
  if (a == null) return 1;
  if (b == null) return -1;
  if (fieldType === 'number') return Number(a) - Number(b);
  if (fieldType === 'date') {
    const dateA = new Date(a).getTime();
    const dateB = new Date(b).getTime();
    return dateA - dateB;
  }
  const strA = String(a).toLowerCase();
  const strB = String(b).toLowerCase();
  return strA.localeCompare(strB);
}

export function applySorting(mails: any[], sortState: SortState): any[] {
  if (!(sortState.conditions?.length ?? 0)) return mails;
  const sorted = [...mails];
  sorted.sort((a, b) => {
    for (const cond of sortState.conditions) {
      const def = SORT_FIELDS.find((f) => f.key === cond.field);
      if (!def) continue;
      const cmp = compareValues(getFieldValue(a, cond.field), getFieldValue(b, cond.field), def.type);
      if (cmp !== 0) return cond.direction === 'desc' ? -cmp : cmp;
    }
    return 0;
  });
  return sorted;
}

let sortIdCounter = 0;
function newSortId() {
  return `msort-${Date.now()}-${++sortIdCounter}`;
}

interface MailSortPanelProps {
  sortState: SortState;
  onSortChange: (sortState: SortState) => void;
}

export function MailSortPanel({ sortState, onSortChange }: MailSortPanelProps) {
  const [open, setOpen] = useState(false);
  const btnRef = useRef<HTMLDivElement>(null);
  const panelRef = useRef<HTMLDivElement>(null);
  const [panelPos, setPanelPos] = useState({ top: 0, left: 0 });

  useEffect(() => {
    if (!open) return;
    const handler = (e: MouseEvent) => {
      const target = e.target as Node;
      if (btnRef.current?.contains(target) || panelRef.current?.contains(target)) return;
      setOpen(false);
    };
    document.addEventListener('mousedown', handler);
    return () => document.removeEventListener('mousedown', handler);
  }, [open]);

  const handleToggle = () => {
    if (!open && btnRef.current) {
      const rect = btnRef.current.getBoundingClientRect();
      const panelWidth = Math.min(400, window.innerWidth * 0.9);
      const left = Math.min(rect.left, window.innerWidth - panelWidth - 10);
      setPanelPos({ top: rect.bottom + 4, left: Math.max(10, left) });
    }
    setOpen(!open);
  };

  const activeCount = sortState.conditions?.length ?? 0;

  const addCondition = () => {
    onSortChange({
      conditions: [...sortState.conditions, { id: newSortId(), field: 'date', direction: 'desc' }],
    });
  };

  const removeCondition = (id: string) => {
    onSortChange({ conditions: sortState.conditions.filter((c) => c.id !== id) });
  };

  const updateCondition = (id: string, updates: Partial<SortCondition>) => {
    onSortChange({
      conditions: sortState.conditions.map((c) => (c.id === id ? { ...c, ...updates } : c)),
    });
  };

  const clearAll = () => onSortChange({ ...emptySortState });

  const groupedFields: Record<string, SortFieldDef[]> = {};
  for (const f of SORT_FIELDS) {
    const g = f.group || 'Allgemein';
    if (!groupedFields[g]) groupedFields[g] = [];
    groupedFields[g].push(f);
  }

  return (
    <>
      <div ref={btnRef} className="relative flex-shrink-0">
        <button
          onClick={handleToggle}
          title="Sortieren"
          aria-label="Sortieren"
          className={`inline-flex items-center gap-1.5 px-2 py-1 rounded text-xs font-medium transition-colors duration-100 cursor-pointer relative ${open || activeCount > 0 ? 'bg-primary-100 text-primary-700' : 'text-secondary-600 hover:bg-secondary-100 hover:text-secondary-900'}`}
        >
          <ArrowUpDown className="w-3.5 h-3.5" strokeWidth={2} />
          {activeCount > 0 && (
            <span className="inline-flex items-center justify-center min-w-[16px] h-4 px-1 text-[10px] font-bold rounded-full bg-primary-600 text-white">{activeCount}</span>
          )}
          <svg className={`w-3 h-3 transition-transform ${open ? 'rotate-180' : ''}`} fill="none" stroke="currentColor" strokeWidth={2} viewBox="0 0 24 24"><polyline points="6 9 12 15 18 9" /></svg>
        </button>
      </div>
      {open && (
        <div ref={panelRef} className="fixed bg-white border border-secondary-200 rounded-lg shadow-lg" style={{ top: panelPos.top, left: panelPos.left, width: 'min(400px, 90vw)', maxHeight: '70vh', overflowY: 'auto', zIndex: 3000 }}>
          <div className="flex items-center justify-between px-4 py-3 border-b border-secondary-100">
            <span className="text-sm font-semibold text-secondary-800">Sortieren</span>
            <div className="flex items-center gap-2">
              {activeCount > 0 && <button onClick={clearAll} className="text-xs text-secondary-500 hover:text-red-600 transition-colors">Alle löschen</button>}
              <button onClick={() => setOpen(false)} className="p-1 rounded hover:bg-secondary-100 text-secondary-400 hover:text-secondary-600"><X className="w-3.5 h-3.5" /></button>
            </div>
          </div>
          <div className="px-4 py-3 space-y-2">
            {sortState.conditions.length === 0 && <div className="text-center py-6 text-xs text-secondary-400">Keine Sortierung aktiv. Klicke unten um ein Feld hinzuzufügen.</div>}
            {sortState.conditions.map((cond, idx) => (
              <div key={cond.id} className="flex items-center gap-1.5">
                <span className="text-[10px] font-bold text-secondary-400 w-6 text-center">{idx + 1}.</span>
                <select value={cond.field} onChange={(e) => updateCondition(cond.id, { field: e.target.value })} className="flex-1 min-w-0 px-2 py-1.5 text-xs border border-secondary-200 rounded bg-white cursor-pointer focus:outline-none focus:border-primary-400">
                  {Object.entries(groupedFields).map(([group, fields]) => (
                    <optgroup key={group} label={group}>{fields.map((f) => (<option key={f.key} value={f.key}>{f.label}</option>))}</optgroup>
                  ))}
                </select>
                <button onClick={() => updateCondition(cond.id, { direction: cond.direction === 'asc' ? 'desc' : 'asc' })} className="p-1.5 rounded border border-secondary-200 hover:bg-secondary-100 text-secondary-600" title={cond.direction === 'asc' ? 'Aufsteigend' : 'Absteigend'}>
                  {cond.direction === 'asc' ? <ChevronUp className="w-3.5 h-3.5" /> : <ChevronDown className="w-3.5 h-3.5" />}
                </button>
                <button onClick={() => removeCondition(cond.id)} className="p-1 rounded hover:bg-red-50 text-secondary-400 hover:text-red-600 transition-colors flex-shrink-0"><X className="w-3.5 h-3.5" /></button>
              </div>
            ))}
          </div>
          <div className="flex items-center justify-between px-4 py-3 border-t border-secondary-100">
            <button onClick={addCondition} className="inline-flex items-center gap-1 px-2 py-1 text-xs font-medium text-primary-600 hover:bg-primary-50 rounded transition-colors"><Plus className="w-3.5 h-3.5" />Feld hinzufügen</button>
            <button onClick={() => setOpen(false)} className="px-3 py-1 text-xs font-medium text-white bg-primary-600 hover:bg-primary-700 rounded transition-colors">Fertig</button>
          </div>
        </div>
      )}
    </>
  );
}