import { useState, useMemo } from 'react'
import { useQuery } from '@tanstack/react-query'
import { Search, Filter, ChevronLeft, ChevronRight, Trash2, Pencil, Plus, AlertTriangle } from 'lucide-react'
import ColorSwatch from '../components/ColorSwatch'
import { fetchFilaments, deleteFilament } from '../services/filamentService'
import type { FilamentSpool, FilamentFilter } from '../types/filament'

const PAGE_SIZE = 20

type SortField = 'name' | 'remaining_grams' | 'cost_usd'
type SortDir = 'asc' | 'desc'

export default function InventoryPage() {
  const [search, setSearch] = useState('')
  const [material, setMaterial] = useState('')
  const [finish, setFinish] = useState('')
  const [lowStockOnly, setLowStockOnly] = useState(false)
  const [sortBy, setSortBy] = useState<SortField>('name')
  const [sortDir, setSortDir] = useState<SortDir>('asc')
  const [page, setPage] = useState(0)
  const [deleteId, setDeleteId] = useState<number | null>(null)

  const filter: FilamentFilter = useMemo(() => ({
    material: material || undefined,
    finish: finish || undefined,
    low_stock: lowStockOnly,
    sort_by: sortBy,
    sort_dir: sortDir,
    limit: PAGE_SIZE,
    offset: page * PAGE_SIZE,
  }), [material, finish, lowStockOnly, sortBy, sortDir, page])

  const { data, isLoading, error, refetch } = useQuery({
    queryKey: ['filaments', filter],
    queryFn: () => fetchFilaments(filter),
  })

  const filaments = data?.data ?? []
  const total = data?.total ?? 0
  const totalPages = Math.max(1, Math.ceil(total / PAGE_SIZE))

  // Client-side search filter (name/barcode) since backend may not support it yet.
  const filtered = useMemo(() => {
    if (!search.trim()) return filaments
    const q = search.toLowerCase()
    return filaments.filter(
      (f: FilamentSpool) =>
        f.name.toLowerCase().includes(q) ||
        (f.barcode && f.barcode.toLowerCase().includes(q))
    )
  }, [filaments, search])

  const handleSort = (field: SortField) => {
    if (sortBy === field) {
      setSortDir(prev => (prev === 'asc' ? 'desc' : 'asc'))
    } else {
      setSortBy(field)
      setSortDir('asc')
    }
    setPage(0)
  }

  const handleDelete = async (id: number) => {
    await deleteFilament(id)
    setDeleteId(null)
    refetch()
  }

  const SortIndicator = ({ field }: { field: SortField }) => {
    if (sortBy !== field) return <span className="text-slate-600 ml-1">↕</span>
    return <span className="text-emerald-400 ml-1">{sortDir === 'asc' ? '↑' : '↓'}</span>
  }

  return (
    <div className="space-y-4">
      {/* Header */}
      <div className="flex flex-col sm:flex-row sm:items-center sm:justify-between gap-3">
        <div>
          <h2 className="text-xl font-bold text-slate-100">Filament Inventory</h2>
          <p className="text-sm text-slate-400">{total} spool(s) total</p>
        </div>
        <button className="inline-flex items-center gap-2 rounded-lg bg-emerald-600 px-4 py-2 text-sm font-semibold text-white hover:bg-emerald-500 active:bg-emerald-700 transition-colors">
          <Plus size={16} /> Add Spool
        </button>
      </div>

      {/* Filters */}
      <div className="flex flex-col lg:flex-row gap-3">
        {/* Search */}
        <div className="relative flex-1">
          <Search size={16} className="absolute left-3 top-1/2 -translate-y-1/2 text-slate-400" />
          <input
            type="text"
            placeholder="Search by name or barcode…"
            value={search}
            onChange={e => { setSearch(e.target.value); setPage(0) }}
            className="w-full rounded-lg bg-slate-800 border border-slate-700 pl-9 pr-3 py-2 text-sm text-slate-100 placeholder-slate-500 focus:outline-none focus:ring-2 focus:ring-emerald-500 focus:border-emerald-500"
          />
        </div>

        {/* Material filter */}
        <select
          value={material}
          onChange={e => { setMaterial(e.target.value); setPage(0) }}
          className="rounded-lg bg-slate-800 border border-slate-700 px-3 py-2 text-sm text-slate-100 focus:outline-none focus:ring-2 focus:ring-emerald-500"
        >
          <option value="">All Materials</option>
          <option value="PLA">PLA</option>
          <option value="PETG">PETG</option>
          <option value="ABS">ABS</option>
          <option value="TPU">TPU</option>
          <option value="ASA">ASA</option>
          <option value="Nylon">Nylon</option>
          <option value="PC">PC</option>
        </select>

        {/* Finish filter */}
        <select
          value={finish}
          onChange={e => { setFinish(e.target.value); setPage(0) }}
          className="rounded-lg bg-slate-800 border border-slate-700 px-3 py-2 text-sm text-slate-100 focus:outline-none focus:ring-2 focus:ring-emerald-500"
        >
          <option value="">All Finishes</option>
          <option value="Basic">Basic</option>
          <option value="Silk">Silk</option>
          <option value="Matte">Matte</option>
          <option value="Glossy">Glossy</option>
          <option value="Wood">Wood</option>
          <option value="Marble">Marble</option>
        </select>

        {/* Low stock toggle */}
        <label className="inline-flex items-center gap-2 rounded-lg bg-slate-800 border border-slate-700 px-3 py-2 text-sm text-slate-100 cursor-pointer select-none hover:bg-slate-750">
          <Filter size={14} className="text-amber-400" />
          <input
            type="checkbox"
            checked={lowStockOnly}
            onChange={e => { setLowStockOnly(e.target.checked); setPage(0) }}
            className="accent-amber-500"
          />
          Low Stock Only
        </label>
      </div>

      {/* Loading / Error */}
      {isLoading && (
        <div className="text-center py-12 text-slate-400">Loading spools…</div>
      )}
      {error && (
        <div className="text-center py-12 text-red-400">
          Failed to load inventory.
          <button onClick={() => refetch()} className="ml-2 underline hover:text-red-300">Retry</button>
        </div>
      )}

      {/* Desktop Table */}
      {!isLoading && !error && (
        <>
          <div className="hidden md:block overflow-x-auto rounded-lg border border-slate-700">
            <table className="w-full text-sm">
              <thead className="bg-slate-800 text-slate-300">
                <tr>
                  <th className="px-4 py-3 text-left font-semibold cursor-pointer select-none hover:text-slate-100" onClick={() => handleSort('name')}>
                    Name <SortIndicator field="name" />
                  </th>
                  <th className="px-4 py-3 text-left font-semibold">Material</th>
                  <th className="px-4 py-3 text-left font-semibold">Finish</th>
                  <th className="px-4 py-3 text-left font-semibold">Color</th>
                  <th className="px-4 py-3 text-right font-semibold cursor-pointer select-none hover:text-slate-100" onClick={() => handleSort('remaining_grams')}>
                    Remaining <SortIndicator field="remaining_grams" />
                  </th>
                  <th className="px-4 py-3 text-right font-semibold cursor-pointer select-none hover:text-slate-100" onClick={() => handleSort('cost_usd')}>
                    Cost <SortIndicator field="cost_usd" />
                  </th>
                  <th className="px-4 py-3 text-center font-semibold">Status</th>
                  <th className="px-4 py-3 text-right font-semibold">Actions</th>
                </tr>
              </thead>
              <tbody className="divide-y divide-slate-700">
                {filtered.length === 0 && (
                  <tr>
                    <td colSpan={8} className="px-4 py-8 text-center text-slate-500">No spools found.</td>
                  </tr>
                )}
                {filtered.map((spool: FilamentSpool) => {
                  const isLow = spool.remaining_grams <= spool.low_stock_threshold_grams
                  return (
                    <tr key={spool.id} className={`${isLow ? 'bg-red-900/20' : 'bg-slate-800/50'} hover:bg-slate-700/50 transition-colors`}>
                      <td className="px-4 py-3 font-medium text-slate-100">{spool.name}</td>
                      <td className="px-4 py-3 text-slate-300">{spool.material_base?.name ?? '—'}</td>
                      <td className="px-4 py-3 text-slate-300">{spool.material_finish?.name ?? '—'}</td>
                      <td className="px-4 py-3">
                        <div className="flex items-center gap-2">
                          <ColorSwatch colorHex={spool.color_hex} size={20} />
                          <span className="text-xs text-slate-400 uppercase">{spool.color_hex}</span>
                        </div>
                      </td>
                      <td className="px-4 py-3 text-right tabular-nums text-slate-200">{spool.remaining_grams.toLocaleString()} g</td>
                      <td className="px-4 py-3 text-right tabular-nums text-slate-300">{spool.cost_usd != null ? `$${spool.cost_usd.toFixed(2)}` : '—'}</td>
                      <td className="px-4 py-3 text-center">
                        {isLow ? (
                          <span className="inline-flex items-center gap-1 rounded-full bg-red-900/50 border border-red-700 px-2 py-0.5 text-xs font-medium text-red-300">
                            <AlertTriangle size={12} /> Low
                          </span>
                        ) : (
                          <span className="inline-flex items-center rounded-full bg-emerald-900/30 border border-emerald-700 px-2 py-0.5 text-xs font-medium text-emerald-300">OK</span>
                        )}
                      </td>
                      <td className="px-4 py-3 text-right">
                        <div className="flex items-center justify-end gap-2">
                          <button className="p-1.5 rounded hover:bg-slate-600 text-slate-400 hover:text-blue-400 transition-colors" title="Edit">
                            <Pencil size={14} />
                          </button>
                          <button
                            onClick={() => setDeleteId(spool.id)}
                            className="p-1.5 rounded hover:bg-slate-600 text-slate-400 hover:text-red-400 transition-colors"
                            title="Delete"
                          >
                            <Trash2 size={14} />
                          </button>
                        </div>
                      </td>
                    </tr>
                  )
                })}
              </tbody>
            </table>
          </div>

          {/* Mobile Cards */}
          <div className="md:hidden space-y-3">
            {filtered.length === 0 && (
              <div className="text-center py-12 text-slate-500">No spools found.</div>
            )}
            {filtered.map((spool: FilamentSpool) => {
              const isLow = spool.remaining_grams <= spool.low_stock_threshold_grams
              return (
                <div key={spool.id} className={`rounded-lg border ${isLow ? 'border-red-700 bg-red-900/10' : 'border-slate-700 bg-slate-800'} p-4 space-y-2`}>
                  <div className="flex items-start justify-between">
                    <div>
                      <div className="font-semibold text-slate-100">{spool.name}</div>
                      <div className="text-xs text-slate-400 mt-0.5">{spool.material_base?.name ?? '—'} · {spool.material_finish?.name ?? '—'}</div>
                    </div>
                    {isLow ? (
                      <span className="inline-flex items-center gap-1 rounded-full bg-red-900/50 border border-red-700 px-2 py-0.5 text-xs font-medium text-red-300">
                        <AlertTriangle size={12} /> Low
                      </span>
                    ) : (
                      <span className="inline-flex items-center rounded-full bg-emerald-900/30 border border-emerald-700 px-2 py-0.5 text-xs font-medium text-emerald-300">OK</span>
                    )}
                  </div>

                  <div className="flex items-center gap-3 text-sm">
                    <div className="flex items-center gap-2">
                      <ColorSwatch colorHex={spool.color_hex} size={20} />
                      <span className="text-slate-400 uppercase text-xs">{spool.color_hex}</span>
                    </div>
                  </div>

                  <div className="flex items-center justify-between text-sm">
                    <span className="text-slate-400">Remaining: <span className="text-slate-200 font-medium tabular-nums">{spool.remaining_grams.toLocaleString()} g</span></span>
                    <span className="text-slate-400">{spool.cost_usd != null ? `$${spool.cost_usd.toFixed(2)}` : '—'}</span>
                  </div>

                  <div className="flex items-center justify-end gap-2 pt-1">
                    <button className="flex items-center gap-1 rounded-md bg-slate-700 px-3 py-1.5 text-xs font-medium text-slate-200 hover:bg-slate-600">
                      <Pencil size={12} /> Edit
                    </button>
                    <button
                      onClick={() => setDeleteId(spool.id)}
                      className="flex items-center gap-1 rounded-md bg-red-900/30 border border-red-700 px-3 py-1.5 text-xs font-medium text-red-300 hover:bg-red-900/50"
                    >
                      <Trash2 size={12} /> Delete
                    </button>
                  </div>
                </div>
              )
            })}
          </div>

          {/* Pagination */}
          <div className="flex items-center justify-between pt-2">
            <span className="text-sm text-slate-400">
              Showing {page * PAGE_SIZE + 1}–{Math.min((page + 1) * PAGE_SIZE, total)} of {total}
            </span>
            <div className="flex items-center gap-2">
              <button
                onClick={() => setPage(p => Math.max(0, p - 1))}
                disabled={page === 0}
                className="p-2 rounded-lg bg-slate-800 border border-slate-700 text-slate-300 hover:bg-slate-700 disabled:opacity-40 disabled:cursor-not-allowed transition-colors"
              >
                <ChevronLeft size={16} />
              </button>
              <span className="text-sm text-slate-300 tabular-nums">{page + 1} / {totalPages}</span>
              <button
                onClick={() => setPage(p => Math.min(totalPages - 1, p + 1))}
                disabled={page >= totalPages - 1}
                className="p-2 rounded-lg bg-slate-800 border border-slate-700 text-slate-300 hover:bg-slate-700 disabled:opacity-40 disabled:cursor-not-allowed transition-colors"
              >
                <ChevronRight size={16} />
              </button>
            </div>
          </div>
        </>
      )}

      {/* Delete confirmation modal */}
      {deleteId !== null && (
        <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/60 backdrop-blur-sm p-4">
          <div className="w-full max-w-sm rounded-xl bg-slate-800 border border-slate-700 p-6 shadow-2xl space-y-4">
            <div className="flex items-center gap-3">
              <div className="flex h-10 w-10 items-center justify-center rounded-full bg-red-900/30">
                <AlertTriangle size={20} className="text-red-400" />
              </div>
              <div>
                <h3 className="text-lg font-semibold text-slate-100">Delete Spool?</h3>
                <p className="text-sm text-slate-400">This action cannot be undone.</p>
              </div>
            </div>
            <div className="flex justify-end gap-3">
              <button
                onClick={() => setDeleteId(null)}
                className="rounded-lg bg-slate-700 px-4 py-2 text-sm font-medium text-slate-200 hover:bg-slate-600 transition-colors"
              >
                Cancel
              </button>
              <button
                onClick={() => handleDelete(deleteId)}
                className="rounded-lg bg-red-600 px-4 py-2 text-sm font-medium text-white hover:bg-red-500 transition-colors"
              >
                Delete
              </button>
            </div>
          </div>
        </div>
      )}
    </div>
  )
}