// Panel 3 — workflow timeline + transition buttons + approval history + changelog.
// Pulls nextPhases từ BE bundle (single source of truth).
import { useState } from 'react'
import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query'
import { toast } from 'sonner'
import { Dialog } from '@/components/ui/Dialog'
import { Button } from '@/components/ui/Button'
import { Label } from '@/components/ui/Label'
import { Textarea } from '@/components/ui/Textarea'
import { api } from '@/lib/api'
import { getErrorMessage } from '@/lib/apiError'
import { cn } from '@/lib/cn'
import {
  ApprovalDecision,
  ApprovalStage,
  BudgetPhase,
  BudgetPhaseColor,
  BudgetPhaseLabel,
  type BudgetDepartmentApproval,
  type BudgetDetailBundle,
} from '@/types/budget'
import { BudgetApprovalsSection, BudgetHistorySection } from './BudgetDetailTabs'

export function BudgetWorkflowPanel({ budget }: { budget: BudgetDetailBundle }) {
  const [target, setTarget] = useState<number | null>(null)
  const [comment, setComment] = useState('')
  const qc = useQueryClient()

  // 2-stage dept approvals (Migration 16) — fetch riêng để FE render timeline.
  const { data: deptApprovals = [] } = useQuery<BudgetDepartmentApproval[]>({
    queryKey: ['budget-dept-approvals', budget.id],
    queryFn: async () => (await api.get(`/budgets/${budget.id}/department-approvals`)).data,
  })

  const transition = useMutation({
    mutationFn: async () =>
      api.post(`/budgets/${budget.id}/transitions`, {
        targetPhase: target,
        decision: target === BudgetPhase.TuChoi ? ApprovalDecision.Reject : ApprovalDecision.Approve,
        comment: comment || null,
      }),
    onSuccess: () => {
      toast.success('Đã chuyển phase.')
      qc.invalidateQueries({ queryKey: ['budget-detail', budget.id] })
      qc.invalidateQueries({ queryKey: ['budget-list'] })
      qc.invalidateQueries({ queryKey: ['budget-changelog', budget.id] })
      qc.invalidateQueries({ queryKey: ['budget-dept-approvals', budget.id] })
      setTarget(null)
      setComment('')
    },
    onError: e => toast.error(getErrorMessage(e)),
  })

  const next = budget.workflow.nextPhases

  return (
    <div className="space-y-4">
      <div>
        <h3 className="text-sm font-semibold text-slate-900">Quy trình</h3>
        <p className="mt-0.5 text-[11px] text-slate-500">{budget.workflow.policyDescription}</p>
      </div>

      <ol className="space-y-1.5">
        {budget.workflow.activePhases
          .filter(p => p !== BudgetPhase.TuChoi)
          .map(p => {
            const isCurrent = budget.phase === p
            const isPast = isPastPhase(budget.phase, p, budget.workflow.activePhases)
            return (
              <li key={p}>
                <div
                  className={cn(
                    'flex items-center gap-2 rounded border px-2 py-1.5 text-xs',
                    isCurrent && 'border-brand-300 bg-brand-50 font-medium',
                    isPast && 'border-emerald-200 bg-emerald-50 text-emerald-700',
                    !isCurrent && !isPast && 'border-slate-200 text-slate-500',
                  )}
                >
                  <span className={cn('rounded px-1.5 py-0.5 text-[10px]', BudgetPhaseColor[p])}>{p}</span>
                  <span className="truncate">{BudgetPhaseLabel[p]}</span>
                  {isCurrent && <span className="ml-auto text-[10px] text-brand-700">● hiện tại</span>}
                  {isPast && <span className="ml-auto text-[10px] text-emerald-600">✓</span>}
                </div>
              </li>
            )
          })}
      </ol>

      {next.length > 0 && (
        <div>
          <Label className="text-xs">Chuyển tiếp:</Label>
          <div className="mt-1 flex flex-wrap gap-1.5">
            {next.map(p => (
              <button
                key={p}
                onClick={() => setTarget(p)}
                className={cn(
                  'rounded border px-2 py-1 text-[11px] transition',
                  p === BudgetPhase.TuChoi
                    ? 'border-red-200 text-red-700 hover:bg-red-50'
                    : p === BudgetPhase.DangSoanThao
                    ? 'border-amber-300 text-amber-700 hover:bg-amber-50'
                    : 'border-brand-300 text-brand-700 hover:bg-brand-50',
                )}
              >
                → {BudgetPhaseLabel[p]}
              </button>
            ))}
          </div>
        </div>
      )}

      {target !== null && (
        <Dialog
          open
          onClose={() => setTarget(null)}
          title={`Chuyển → ${BudgetPhaseLabel[target]}`}
          footer={<>
            <Button variant="ghost" onClick={() => setTarget(null)}>Hủy</Button>
            <Button onClick={() => transition.mutate()} disabled={transition.isPending}>Xác nhận</Button>
          </>}
        >
          <Label>Ghi chú (tùy chọn)</Label>
          <Textarea value={comment} onChange={e => setComment(e.target.value)} rows={3} />
        </Dialog>
      )}

      {deptApprovals.length > 0 && (
        <div className="border-t border-slate-200 pt-4">
          <BudgetDeptApprovalsSection rows={deptApprovals} currentPhase={budget.phase} />
        </div>
      )}

      <div className="border-t border-slate-200 pt-4">
        <BudgetApprovalsSection budget={budget} />
      </div>

      <div className="border-t border-slate-200 pt-4">
        <BudgetHistorySection budget={budget} />
      </div>
    </div>
  )
}

// 2-stage dept approval timeline (Migration 16) — mirror PE/Contract pattern.
function BudgetDeptApprovalsSection({
  rows,
  currentPhase,
}: {
  rows: BudgetDepartmentApproval[]
  currentPhase: number
}) {
  const grouped = new Map<number, Map<string, BudgetDepartmentApproval[]>>()
  for (const r of rows) {
    if (!grouped.has(r.phaseAtApproval)) grouped.set(r.phaseAtApproval, new Map())
    const byDept = grouped.get(r.phaseAtApproval)!
    if (!byDept.has(r.departmentId)) byDept.set(r.departmentId, [])
    byDept.get(r.departmentId)!.push(r)
  }
  const phaseOrder = [...grouped.keys()].sort((a, b) => a - b)

  return (
    <div>
      <h3 className="text-sm font-semibold text-slate-900">Tiến trình duyệt 2-cấp phòng ban</h3>
      <p className="mt-0.5 text-[11px] text-slate-500">NV Review → TPB Confirm. Phase chỉ chuyển khi có Confirm.</p>
      <div className="mt-2 space-y-3">
        {phaseOrder.map(phase => {
          const byDept = grouped.get(phase)!
          return (
            <div key={phase}>
              <div className={cn(
                'inline-block rounded px-1.5 py-0.5 text-[10px] font-medium',
                BudgetPhaseColor[phase] ?? 'bg-slate-100 text-slate-700',
              )}>
                {BudgetPhaseLabel[phase] ?? `Phase ${phase}`}
              </div>
              <div className="mt-1 space-y-1.5">
                {[...byDept.entries()].map(([deptId, stages]) => {
                  const review = stages.find(s => s.stage === ApprovalStage.Review)
                  const confirm = stages.find(s => s.stage === ApprovalStage.Confirm)
                  const deptName = stages[0]?.departmentName ?? '(không rõ phòng)'
                  const isPending = phase === currentPhase && review && !confirm
                  return (
                    <div key={deptId} className={cn(
                      'rounded border px-2 py-1.5 text-[11px]',
                      isPending ? 'border-amber-300 bg-amber-50' : 'border-slate-200 bg-slate-50',
                    )}>
                      <div className="font-medium text-slate-700">{deptName}</div>
                      <div className="mt-1 grid grid-cols-[60px_1fr] gap-x-2 gap-y-0.5">
                        <span className="text-slate-500">Review:</span>
                        <span className={review ? 'text-slate-700' : 'text-slate-400'}>
                          {review
                            ? <>✓ {review.approverName} <span className="text-slate-500">— {fmtTime(review.approvedAt)}</span>{review.comment && <span className="text-slate-500"> · "{review.comment}"</span>}</>
                            : '— chưa có'}
                        </span>
                        <span className="text-slate-500">Confirm:</span>
                        <span className={confirm ? 'text-emerald-700' : 'text-amber-700'}>
                          {confirm
                            ? <>✓ {confirm.approverName}{confirm.isBypassed && <span className="ml-1 rounded bg-fuchsia-100 px-1 text-[9px] text-fuchsia-700">bypass</span>} <span className="text-slate-500">— {fmtTime(confirm.approvedAt)}</span>{confirm.comment && <span className="text-slate-500"> · "{confirm.comment}"</span>}</>
                            : '⏳ chờ TPB confirm'}
                        </span>
                      </div>
                    </div>
                  )
                })}
              </div>
            </div>
          )
        })}
      </div>
    </div>
  )
}

function fmtTime(iso: string): string {
  const d = new Date(iso)
  return d.toLocaleString('vi-VN', { day: '2-digit', month: '2-digit', hour: '2-digit', minute: '2-digit' })
}

function isPastPhase(current: number, p: number, active: number[]): boolean {
  const orderedIdx = active.indexOf(p)
  const currentIdx = active.indexOf(current)
  if (orderedIdx < 0 || currentIdx < 0) return false
  return orderedIdx < currentIdx && p !== BudgetPhase.TuChoi
}