'use client'

import { useState, useEffect } from 'react'
import { AlertTriangle, Bot, CheckCircle2 } from 'lucide-react'
import { toast } from 'sonner'
import { trpc } from '@/lib/trpc/client'
import {
  Sheet,
  SheetContent,
  SheetDescription,
  SheetFooter,
  SheetHeader,
  SheetTitle,
} from '@/components/ui/sheet'
import { Button } from '@/components/ui/button'
import { ScrollArea } from '@/components/ui/scroll-area'
import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card'
import { Badge } from '@/components/ui/badge'
import { Skeleton } from '@/components/ui/skeleton'

interface AssignmentPreviewSheetProps {
  roundId: string
  open: boolean
  onOpenChange: (open: boolean) => void
}

export function AssignmentPreviewSheet({
  roundId,
  open,
  onOpenChange,
}: AssignmentPreviewSheetProps) {
  const utils = trpc.useUtils()

  const {
    data: preview,
    isLoading,
    refetch,
  } = trpc.roundAssignment.preview.useQuery(
    { roundId, honorIntents: true, requiredReviews: 3 },
    { enabled: open }
  )

  const { mutate: execute, isPending: isExecuting } = trpc.roundAssignment.execute.useMutation({
    onSuccess: (result) => {
      toast.success(`Created ${result.created} assignments`)
      utils.roundAssignment.coverageReport.invalidate({ roundId })
      utils.roundAssignment.unassignedQueue.invalidate({ roundId })
      utils.assignment.listByStage.invalidate({ roundId })
      utils.roundEngine.getProjectStates.invalidate({ roundId })
      onOpenChange(false)
    },
    onError: (err) => {
      toast.error(err.message)
    },
  })

  useEffect(() => {
    if (open) {
      refetch()
    }
  }, [open, refetch])

  const handleExecute = () => {
    if (!preview?.assignments || preview.assignments.length === 0) {
      toast.error('No assignments to execute')
      return
    }

    execute({
      roundId,
      assignments: preview.assignments.map((a: any) => ({
        userId: a.userId,
        projectId: a.projectId,
      })),
    })
  }

  return (
    <Sheet open={open} onOpenChange={onOpenChange}>
      <SheetContent className="w-full sm:max-w-xl">
        <SheetHeader>
          <SheetTitle>Assignment Preview</SheetTitle>
          <SheetDescription className="flex items-center gap-2">
            <Badge variant="outline" className="text-xs gap-1 shrink-0">
              <Bot className="h-3 w-3" />
              AI Suggested
            </Badge>
            Review the proposed assignments before executing. All assignments are admin-approved on execute.
          </SheetDescription>
        </SheetHeader>

        <ScrollArea className="h-[calc(100vh-200px)] mt-6">
          {isLoading ? (
            <div className="space-y-3">
              {[1, 2, 3].map((i) => (
                <Skeleton key={i} className="h-20 w-full" />
              ))}
            </div>
          ) : preview ? (
            <div className="space-y-4">
              <Card>
                <CardHeader>
                  <CardTitle className="text-sm flex items-center gap-2">
                    <CheckCircle2 className="h-4 w-4 text-green-600" />
                    {preview.stats.assignmentsGenerated || 0} Assignments Proposed
                </CardTitle>
                </CardHeader>
                <CardContent>
                  <p className="text-sm text-muted-foreground">
                    {preview.stats.totalJurors || 0} jurors will receive assignments
                  </p>
                </CardContent>
              </Card>

              {preview.warnings && preview.warnings.length > 0 && (
                <Card className="border-amber-500">
                  <CardHeader>
                    <CardTitle className="text-sm flex items-center gap-2">
                      <AlertTriangle className="h-4 w-4 text-amber-600" />
                      Warnings ({preview.warnings.length})
                    </CardTitle>
                  </CardHeader>
                  <CardContent>
                    <ul className="space-y-2 text-sm">
                      {preview.warnings.map((warning: string, idx: number) => (
                        <li key={idx} className="flex items-start gap-2">
                          <span className="text-amber-600">•</span>
                          <span>{warning}</span>
                        </li>
                      ))}
                    </ul>
                  </CardContent>
                </Card>
              )}

              {preview.assignments && preview.assignments.length > 0 && (
                <Card>
                  <CardHeader>
                    <CardTitle className="text-sm">Assignment Summary</CardTitle>
                  </CardHeader>
                  <CardContent>
                    <div className="space-y-2 text-sm">
                      <div className="flex justify-between">
                        <span className="text-muted-foreground">Total assignments:</span>
                        <span className="font-medium">{preview.assignments.length}</span>
                      </div>
                      <div className="flex justify-between">
                        <span className="text-muted-foreground">Unique projects:</span>
                        <span className="font-medium">
                          {new Set(preview.assignments.map((a: any) => a.projectId)).size}
                        </span>
                      </div>
                      <div className="flex justify-between">
                        <span className="text-muted-foreground">Unique jurors:</span>
                        <span className="font-medium">
                          {new Set(preview.assignments.map((a: any) => a.userId)).size}
                        </span>
                      </div>
                    </div>
                  </CardContent>
                </Card>
              )}
            </div>
          ) : (
            <p className="text-sm text-muted-foreground">No preview data available</p>
          )}
        </ScrollArea>

        <SheetFooter className="mt-6">
          <Button variant="outline" onClick={() => onOpenChange(false)}>
            Cancel
          </Button>
          <Button
            onClick={handleExecute}
            disabled={isExecuting || !preview?.assignments || preview.assignments.length === 0}
          >
            {isExecuting ? 'Executing...' : 'Execute Assignments'}
          </Button>
        </SheetFooter>
      </SheetContent>
    </Sheet>
  )
}