import { Fragment, useMemo, useState } from 'react'
import { computeBom } from '../../domain/bom'
import { useCatalogStore } from '../../state/catalogStore'
import { useProjectStore } from '../../state/projectStore'
import Chevron from '../common/Chevron'

function formatCost(value: number): string {
  return `$${value.toFixed(2)}`
}

export default function BomPanel() {
  const project = useProjectStore((s) => s.project)
  const catalog = useCatalogStore((s) => s.catalog)
  const bom = useMemo(() => computeBom(project, catalog), [project, catalog])
  // Collapsed by default, per cable type — most diagrams only need the
  // per-type totals; the length breakdown is there when you're ready to
  // actually go buy cables.
  const [expandedCableTypeIds, setExpandedCableTypeIds] = useState<Set<string>>(new Set())

  const toggleCableType = (cableTypeId: string) => {
    setExpandedCableTypeIds((prev) => {
      const next = new Set(prev)
      if (next.has(cableTypeId)) next.delete(cableTypeId)
      else next.add(cableTypeId)
      return next
    })
  }

  const hasMissingCost =
    bom.devices.some((line) => line.devicesMissingCost > 0) || bom.cables.some((line) => line.connectionsMissingCost > 0)

  return (
    <div className="space-y-4 p-3">
      <section>
        <h4 className="mb-1 text-xs font-semibold uppercase tracking-wide text-slate-500">Devices</h4>
        {bom.devices.length === 0 ? (
          <p className="text-xs italic text-slate-400">No devices on the canvas yet.</p>
        ) : (
          <table className="w-full text-xs">
            <thead>
              <tr className="text-left text-[10px] uppercase tracking-wide text-slate-400">
                <th className="pb-1 font-medium">Device</th>
                <th className="pb-1 text-right font-medium">Count</th>
                <th className="pb-1 text-right font-medium">Cost</th>
              </tr>
            </thead>
            <tbody>
              {bom.devices.map((line) => (
                <tr key={line.key} className="border-b border-slate-100 last:border-0">
                  <td className="py-1 pr-2">
                    <div className="font-medium text-slate-700">{line.name}</div>
                    {(line.manufacturer || line.model) && (
                      <div className="text-[10px] text-slate-400">
                        {[line.manufacturer, line.model].filter(Boolean).join(' ')}
                      </div>
                    )}
                  </td>
                  <td className="py-1 text-right font-medium text-slate-600">×{line.count}</td>
                  <td className="py-1 text-right text-slate-600">
                    {line.totalCost > 0 ? formatCost(line.totalCost) : '—'}
                    {line.devicesMissingCost > 0 && (
                      <span className="ml-1 text-[10px] text-amber-500" title="Some devices are missing a cost">
                        ({line.devicesMissingCost} unset)
                      </span>
                    )}
                  </td>
                </tr>
              ))}
            </tbody>
          </table>
        )}
      </section>

      <section>
        <h4 className="mb-1 text-xs font-semibold uppercase tracking-wide text-slate-500">Cables</h4>
        {bom.cables.length === 0 ? (
          <p className="text-xs italic text-slate-400">No cables wired up yet.</p>
        ) : (
          <table className="w-full text-xs">
            <thead>
              <tr className="text-left text-[10px] uppercase tracking-wide text-slate-400">
                <th className="pb-1 font-medium">Cable</th>
                <th className="pb-1 text-right font-medium">Count</th>
                <th className="pb-1 text-right font-medium">Total length</th>
                <th className="pb-1 text-right font-medium">Cost</th>
              </tr>
            </thead>
            <tbody>
              {bom.cables.map((line) => {
                const expandable = line.lengths.length > 1
                const expanded = expandable && expandedCableTypeIds.has(line.cableTypeId)
                return (
                  <Fragment key={line.cableTypeId}>
                    <tr className="border-b border-slate-100 last:border-0">
                      <td className="py-1 pr-2 font-medium text-slate-700">
                        {expandable ? (
                          <button
                            onClick={() => toggleCableType(line.cableTypeId)}
                            className="flex items-center gap-1 hover:text-indigo-700"
                          >
                            <Chevron expanded={expanded} className="text-slate-400" />
                            {line.cableTypeName}
                          </button>
                        ) : (
                          <span className="pl-[1.1rem]">{line.cableTypeName}</span>
                        )}
                      </td>
                      <td className="py-1 text-right text-slate-600">×{line.count}</td>
                      <td className="py-1 text-right text-slate-600">
                        {line.totalLength > 0 ? `${line.totalLength}${line.unit}` : '—'}
                        {line.connectionsMissingLength > 0 && (
                          <span className="ml-1 text-[10px] text-amber-500" title="Some cables are missing a distance">
                            ({line.connectionsMissingLength} unset)
                          </span>
                        )}
                      </td>
                      <td className="py-1 text-right text-slate-600">
                        {line.totalCost > 0 ? formatCost(line.totalCost) : '—'}
                        {line.connectionsMissingCost > 0 && (
                          <span className="ml-1 text-[10px] text-amber-500" title="Some cables are missing a computable cost">
                            ({line.connectionsMissingCost} unset)
                          </span>
                        )}
                      </td>
                    </tr>
                    {expanded &&
                      line.lengths.map((lengthLine) => (
                        <tr key={`${line.cableTypeId}-${lengthLine.distance ?? 'unset'}`} className="border-b border-slate-50 last:border-0">
                          <td className="py-0.5 pl-6 pr-2 text-slate-500">
                            {lengthLine.distance !== undefined ? `${lengthLine.distance}${line.unit}` : 'No length set'}
                          </td>
                          <td className="py-0.5 text-right text-slate-500">×{lengthLine.count}</td>
                          <td className="py-0.5 text-right text-slate-500">
                            {lengthLine.totalLength > 0 ? `${lengthLine.totalLength}${line.unit}` : '—'}
                          </td>
                          <td className="py-0.5 text-right text-slate-500">
                            {lengthLine.totalCost > 0 ? formatCost(lengthLine.totalCost) : '—'}
                            {lengthLine.connectionsMissingCost > 0 && (
                              <span className="ml-1 text-[10px] text-amber-500" title="Some cables are missing a computable cost">
                                ({lengthLine.connectionsMissingCost} unset)
                              </span>
                            )}
                          </td>
                        </tr>
                      ))}
                  </Fragment>
                )
              })}
            </tbody>
          </table>
        )}
      </section>

      {(bom.devices.length > 0 || bom.cables.length > 0) && (
        <section className="border-t border-slate-200 pt-2">
          <div className="flex items-center justify-between text-xs">
            <span className="font-semibold uppercase tracking-wide text-slate-500">Grand total</span>
            <span className="font-semibold text-slate-700">{formatCost(bom.grandTotalCost)}</span>
          </div>
          {hasMissingCost && (
            <p className="mt-0.5 text-[10px] text-amber-500">
              Some items are missing a cost and are excluded from this total.
            </p>
          )}
        </section>
      )}
    </div>
  )
}