import { useState, useEffect, useCallback } from 'react'
import { Link, useNavigate } from 'react-router-dom'
import { Globe, Users, Copy, Check, ExternalLink, Trash2, ArrowLeft } from 'lucide-react'
import { PageMeta } from '@/components/common/PageMeta'
import { Button } from '@/components/ui/Button'
import { Spinner } from '@/components/common/Spinner'
import { EmptyState } from '@/components/common/EmptyState'
import { ShareIllustration } from '@/components/common/EmptyStateIllustrations'
import { ConfirmDialog } from '@/components/common/ConfirmDialog'
import { cn } from '@/lib/utils'
import { toast } from '@/lib/toast'
import { sessionsApi } from '@/api/sessions'
import { buildSessionShareUrl } from '@/lib/sessionShare'
import type { SessionShare } from '@/types'

function formatRelativeTime(dateString: string): string {
  const date = new Date(dateString)
  const now = new Date()
  const diffMs = now.getTime() - date.getTime()
  const diffMinutes = Math.floor(diffMs / 60000)
  const diffHours = Math.floor(diffMs / 3600000)
  const diffDays = Math.floor(diffMs / 86400000)

  if (diffMinutes < 1) return 'just now'
  if (diffHours < 1) return `${diffMinutes} minute${diffMinutes === 1 ? '' : 's'} ago`
  if (diffDays < 1) return `${diffHours} hour${diffHours === 1 ? '' : 's'} ago`
  if (diffDays < 30) return `${diffDays} day${diffDays === 1 ? '' : 's'} ago`
  const diffMonths = Math.floor(diffDays / 30)
  return `${diffMonths} month${diffMonths === 1 ? '' : 's'} ago`
}

function formatExpiration(expiresAt: string | null): { text: string; isExpired: boolean } {
  if (!expiresAt) return { text: 'No expiration', isExpired: false }

  const expiry = new Date(expiresAt)
  const now = new Date()
  const diffMs = expiry.getTime() - now.getTime()

  if (diffMs <= 0) return { text: 'Expired', isExpired: true }

  const diffMinutes = Math.floor(diffMs / 60000)
  const diffHours = Math.floor(diffMs / 3600000)
  const diffDays = Math.floor(diffMs / 86400000)

  if (diffHours < 1) return { text: `Expires in ${diffMinutes} minute${diffMinutes === 1 ? '' : 's'}`, isExpired: false }
  if (diffDays < 1) return { text: `Expires in ${diffHours} hour${diffHours === 1 ? '' : 's'}`, isExpired: false }
  return { text: `Expires in ${diffDays} day${diffDays === 1 ? '' : 's'}`, isExpired: false }
}

export default function MySharesPage() {
  const navigate = useNavigate()
  const [shares, setShares] = useState<SessionShare[]>([])
  const [loading, setLoading] = useState(true)
  const [error, setError] = useState<string | null>(null)
  const [copiedId, setCopiedId] = useState<string | null>(null)
  const [revokeTarget, setRevokeTarget] = useState<SessionShare | null>(null)

  const fetchShares = useCallback(async () => {
    try {
      setLoading(true)
      setError(null)
      const data = await sessionsApi.listMyShares()
      setShares(data)
    } catch (err) {
      setError(err instanceof Error ? err.message : 'Failed to load shares')
    } finally {
      setLoading(false)
    }
  }, [])

  useEffect(() => {
    fetchShares()
  }, [fetchShares])

  const handleCopyLink = async (share: SessionShare) => {
    try {
      const url = buildSessionShareUrl(share)
      await navigator.clipboard.writeText(url)
      setCopiedId(share.id)
      toast.success('Link copied')
      setTimeout(() => setCopiedId(null), 2000)
    } catch {
      toast.error('Failed to copy link')
    }
  }

  const handleRevoke = async () => {
    if (!revokeTarget) return
    try {
      await sessionsApi.revokeShare(revokeTarget.id)
      setShares((prev) => prev.filter((s) => s.id !== revokeTarget.id))
      toast.success('Share link revoked')
    } catch {
      toast.error('Failed to revoke share link')
    } finally {
      setRevokeTarget(null)
    }
  }

  // Loading state
  if (loading) {
    return (
      <div className="flex items-center justify-center py-32">
        <Spinner />
      </div>
    )
  }

  // Error state
  if (error) {
    return (
      <div className="container mx-auto px-4 py-6 sm:px-6 sm:py-8">
        <div className="bg-card border border-red-400/20 rounded-xl p-6">
          <div className="text-center">
            <p className="text-red-400 text-sm mb-4">{error}</p>
            <Button onClick={fetchShares}>
              Try again
            </Button>
          </div>
        </div>
      </div>
    )
  }

  return (
    <div className="overflow-y-auto h-full">
    <PageMeta title="My Shares" />
    <div className="container mx-auto px-4 py-6 sm:px-6 sm:py-8">
      {/* Back link */}
      <Link
        to="/sessions"
        className="inline-flex items-center gap-1.5 text-sm text-muted-foreground hover:text-foreground transition-colors mb-6"
      >
        <ArrowLeft className="h-4 w-4" />
        Back to sessions
      </Link>

      {/* Header */}
      <div className="mb-6">
        <h1 className="text-2xl font-heading font-bold text-foreground">My Shared Sessions</h1>
        <p className="text-muted-foreground mt-1">Manage your session share links</p>
      </div>

      {/* Empty state */}
      {shares.length === 0 ? (
        <EmptyState
          illustration={<ShareIllustration />}
          title="Share session results with your team"
          description="Create shareable links to completed sessions for knowledge sharing and client communication."
          action={
            <Button onClick={() => navigate('/sessions')}>
              View Sessions
            </Button>
          }
          learnMoreLink="/guides/sharing-exports"
        />
      ) : (
        <div className="space-y-4">
          {shares.map((share) => {
            const expiration = formatExpiration(share.expires_at)
            const isCopied = copiedId === share.id

            return (
              <div key={share.id} className="bg-card border border-border rounded-xl p-5">
                {/* Top row: badge + name */}
                <div className="flex items-center gap-3 mb-3">
                  <span className="inline-flex items-center gap-1.5 text-xs rounded-full px-2 py-0.5 bg-accent text-muted-foreground">
                    {share.visibility === 'public' ? (
                      <Globe className="h-3 w-3" />
                    ) : (
                      <Users className="h-3 w-3" />
                    )}
                    {share.visibility === 'public' ? 'Public' : 'Account Only'}
                  </span>
                  <span className="text-sm font-medium text-foreground">
                    {share.share_name || 'Untitled share'}
                  </span>
                </div>

                {/* Session info */}
                <p className="text-sm text-muted-foreground mb-2">
                  Session ID: {share.session_id.slice(0, 8)}...
                </p>

                {/* Meta row */}
                <div className="flex flex-wrap items-center gap-x-4 gap-y-1 text-xs text-muted-foreground mb-4">
                  <span>Created {formatRelativeTime(share.created_at)}</span>
                  <span className="hidden sm:inline">·</span>
                  <span>
                    {share.view_count > 0
                      ? `${share.view_count} view${share.view_count === 1 ? '' : 's'}`
                      : 'Not viewed yet'}
                  </span>
                  <span className="hidden sm:inline">·</span>
                  <span className={cn(expiration.isExpired && 'text-red-400')}>
                    {expiration.text}
                  </span>
                </div>

                {/* Actions */}
                <div className="flex flex-wrap items-center gap-2">
                  <Button
                    size="sm"
                    onClick={() => handleCopyLink(share)}
                    className={isCopied ? 'bg-emerald-400/10 text-emerald-400 shadow-none hover:opacity-100' : ''}
                  >
                    {isCopied ? (
                      <Check className="h-3.5 w-3.5" />
                    ) : (
                      <Copy className="h-3.5 w-3.5" />
                    )}
                    {isCopied ? 'Copied' : 'Copy Link'}
                  </Button>

                  <Link
                    to={`/sessions/${share.session_id}`}
                    className="inline-flex items-center gap-1.5 border border-border text-muted-foreground hover:bg-accent rounded-md px-3 py-1.5 text-sm transition-colors"
                  >
                    <ExternalLink className="h-3.5 w-3.5" />
                    View Session
                  </Link>

                  <Button
                    variant="destructive"
                    size="sm"
                    onClick={() => setRevokeTarget(share)}
                  >
                    <Trash2 className="h-3.5 w-3.5" />
                    Revoke
                  </Button>
                </div>
              </div>
            )
          })}
        </div>
      )}

      <ConfirmDialog
        isOpen={!!revokeTarget}
        onClose={() => setRevokeTarget(null)}
        onConfirm={handleRevoke}
        title="Revoke Share Link"
        message="Revoke this share link? Anyone with the link will no longer be able to access the session."
        confirmLabel="Revoke"
      />
    </div>
    </div>
  )
}