'use client'

import Link from 'next/link'
import { Badge } from '@/components/ui/badge'
import {
  Tooltip,
  TooltipContent,
  TooltipProvider,
  TooltipTrigger,
} from '@/components/ui/tooltip'
import {
  Filter,
  ClipboardCheck,
  Zap,
  CheckCircle2,
  Clock,
  Archive,
  ChevronRight,
  FileText,
  Users,
  AlertTriangle,
} from 'lucide-react'
import { cn } from '@/lib/utils'

type PipelineRound = {
  id: string
  name: string
  status: string
  roundType: string
  _count?: {
    projects: number
    assignments: number
  }
}

interface RoundPipelineProps {
  rounds: PipelineRound[]
  programName?: string
}

const typeIcons: Record<string, typeof Filter> = {
  FILTERING: Filter,
  EVALUATION: ClipboardCheck,
  LIVE_EVENT: Zap,
}

const typeColors: Record<string, { bg: string; text: string; border: string }> = {
  FILTERING: {
    bg: 'bg-amber-50 dark:bg-amber-950/30',
    text: 'text-amber-700 dark:text-amber-300',
    border: 'border-amber-200 dark:border-amber-800',
  },
  EVALUATION: {
    bg: 'bg-blue-50 dark:bg-blue-950/30',
    text: 'text-blue-700 dark:text-blue-300',
    border: 'border-blue-200 dark:border-blue-800',
  },
  LIVE_EVENT: {
    bg: 'bg-violet-50 dark:bg-violet-950/30',
    text: 'text-violet-700 dark:text-violet-300',
    border: 'border-violet-200 dark:border-violet-800',
  },
}

const statusConfig: Record<string, { color: string; icon: typeof CheckCircle2; label: string }> = {
  DRAFT: { color: 'text-muted-foreground', icon: Clock, label: 'Draft' },
  ACTIVE: { color: 'text-green-600', icon: CheckCircle2, label: 'Active' },
  CLOSED: { color: 'text-amber-600', icon: Archive, label: 'Closed' },
  ARCHIVED: { color: 'text-muted-foreground', icon: Archive, label: 'Archived' },
}

export function RoundPipeline({ rounds }: RoundPipelineProps) {
  if (rounds.length === 0) return null

  // Detect bottlenecks: rounds with many more incoming projects than outgoing
  const projectCounts = rounds.map((r) => r._count?.projects || 0)

  return (
    <div className="w-full overflow-x-auto pb-2">
      <div className="flex items-stretch gap-1 min-w-max px-1 py-2">
        {rounds.map((round, index) => {
          const TypeIcon = typeIcons[round.roundType] || ClipboardCheck
          const colors = typeColors[round.roundType] || typeColors.EVALUATION
          const status = statusConfig[round.status] || statusConfig.DRAFT
          const StatusIcon = status.icon
          const projectCount = round._count?.projects || 0
          const prevCount = index > 0 ? projectCounts[index - 1] : 0
          const dropRate = prevCount > 0 ? Math.round(((prevCount - projectCount) / prevCount) * 100) : 0
          const isBottleneck = dropRate > 50 && index > 0

          return (
            <div key={round.id} className="flex items-center">
              {/* Round Card */}
              <TooltipProvider>
                <Tooltip>
                  <TooltipTrigger asChild>
                    <Link
                      href={`/admin/rounds/${round.id}`}
                      className={cn(
                        'group relative flex flex-col items-center gap-2 rounded-xl border-2 px-5 py-4 transition-all duration-200 hover:shadow-lg hover:-translate-y-1 min-w-[140px]',
                        colors.bg,
                        colors.border,
                        round.status === 'ACTIVE' && 'ring-2 ring-green-500/30'
                      )}
                    >
                      {/* Status indicator dot */}
                      <div className="absolute -top-1.5 -right-1.5">
                        <div className={cn(
                          'h-3.5 w-3.5 rounded-full border-2 border-background',
                          round.status === 'ACTIVE' ? 'bg-green-500' :
                          round.status === 'CLOSED' ? 'bg-amber-500' :
                          round.status === 'DRAFT' ? 'bg-muted-foreground/40' :
                          'bg-muted-foreground/20'
                        )} />
                      </div>

                      {/* Type Icon */}
                      <div className={cn(
                        'rounded-lg p-2',
                        round.status === 'ACTIVE' ? 'bg-green-100 dark:bg-green-900/30' : 'bg-background'
                      )}>
                        <TypeIcon className={cn('h-5 w-5', colors.text)} />
                      </div>

                      {/* Round Name */}
                      <p className="text-sm font-medium text-center line-clamp-2 leading-tight max-w-[120px]">
                        {round.name}
                      </p>

                      {/* Stats Row */}
                      <div className="flex items-center gap-3 text-xs text-muted-foreground">
                        <span className="flex items-center gap-1">
                          <FileText className="h-3 w-3" />
                          {projectCount}
                        </span>
                        {round._count?.assignments !== undefined && round._count.assignments > 0 && (
                          <span className="flex items-center gap-1">
                            <Users className="h-3 w-3" />
                            {round._count.assignments}
                          </span>
                        )}
                      </div>

                      {/* Status Badge */}
                      <Badge
                        variant="outline"
                        className={cn('text-[10px] px-1.5 py-0', status.color)}
                      >
                        <StatusIcon className="mr-1 h-2.5 w-2.5" />
                        {status.label}
                      </Badge>

                      {/* Bottleneck indicator */}
                      {isBottleneck && (
                        <div className="absolute -bottom-2 left-1/2 -translate-x-1/2">
                          <AlertTriangle className="h-4 w-4 text-amber-500" />
                        </div>
                      )}
                    </Link>
                  </TooltipTrigger>
                  <TooltipContent side="bottom" className="max-w-xs">
                    <div className="space-y-1">
                      <p className="font-medium">{round.name}</p>
                      <p className="text-xs capitalize">
                        {round.roundType.toLowerCase().replace('_', ' ')} &middot; {round.status.toLowerCase()}
                      </p>
                      <p className="text-xs">
                        {projectCount} projects
                        {round._count?.assignments ? `, ${round._count.assignments} assignments` : ''}
                      </p>
                      {isBottleneck && (
                        <p className="text-xs text-amber-600">
                          {dropRate}% drop from previous round
                        </p>
                      )}
                    </div>
                  </TooltipContent>
                </Tooltip>
              </TooltipProvider>

              {/* Arrow connector */}
              {index < rounds.length - 1 && (
                <div className="flex flex-col items-center px-2">
                  <ChevronRight className="h-5 w-5 text-muted-foreground/40" />
                  {prevCount > 0 && index > 0 && dropRate > 0 && (
                    <span className="text-[10px] text-muted-foreground/60 -mt-0.5">
                      -{dropRate}%
                    </span>
                  )}
                  {index === 0 && projectCounts[0] > 0 && projectCounts[1] !== undefined && (
                    <span className="text-[10px] text-muted-foreground/60 -mt-0.5">
                      {projectCounts[0]} &rarr; {projectCounts[1] || '?'}
                    </span>
                  )}
                </div>
              )}
            </div>
          )
        })}
      </div>
    </div>
  )
}