'use client'

import { useEffect, useMemo, useState } from 'react'
import { trpc } from '@/lib/trpc/client'
import { toast } from 'sonner'
import {
  Dialog, DialogContent, DialogDescription, DialogFooter, DialogHeader, DialogTitle,
} from '@/components/ui/dialog'
import { Button } from '@/components/ui/button'
import { Input } from '@/components/ui/input'
import { Label } from '@/components/ui/label'
import { Textarea } from '@/components/ui/textarea'
import { Mail, Send, Eye } from 'lucide-react'

interface Props {
  open: boolean
  onClose: () => void
  projectId: string
  projectTitle: string
}

function useDebounced<T>(value: T, delayMs: number): T {
  const [debounced, setDebounced] = useState(value)
  useEffect(() => {
    const t = setTimeout(() => setDebounced(value), delayMs)
    return () => clearTimeout(t)
  }, [value, delayMs])
  return debounced
}

export function ProjectEmailDialog({ open, onClose, projectId, projectTitle }: Props) {
  const initialBody = useMemo(() => `Hello ${projectTitle} team,\n\n`, [projectTitle])
  const [subject, setSubject] = useState('')
  const [body, setBody] = useState(initialBody)
  const [showPreview, setShowPreview] = useState(false)

  // Reset state whenever the dialog opens for a new project
  useEffect(() => {
    if (open) {
      setSubject('')
      setBody(initialBody)
      setShowPreview(false)
    }
  }, [open, initialBody])

  const debouncedSubject = useDebounced(subject, 300)
  const debouncedBody = useDebounced(body, 300)

  const recipientPreview = trpc.message.previewRecipients.useQuery(
    { recipientType: 'PROJECT_TEAM', recipientFilter: { projectId } },
    { enabled: open }
  )

  const emailPreview = trpc.message.previewEmail.useQuery(
    { subject: debouncedSubject, body: debouncedBody },
    { enabled: showPreview && debouncedSubject.length > 0 && debouncedBody.length > 0 }
  )

  const sendTestMutation = trpc.message.sendTest.useMutation({
    onSuccess: ({ to }) => toast.success(`Test email sent to ${to}`),
    onError: (e) => toast.error(e.message),
  })

  const sendMutation = trpc.message.send.useMutation({
    onSuccess: () => {
      toast.success(`Email sent to ${recipientPreview.data?.totalApplicants ?? 0} team members`)
      onClose()
    },
    onError: (e) => toast.error(e.message),
  })

  const recipientCount = recipientPreview.data?.totalApplicants ?? 0
  const canSend = subject.length > 0 && body.length > 0 && recipientCount > 0

  return (
    <Dialog open={open} onOpenChange={(v) => !v && onClose()}>
      <DialogContent className="max-w-2xl max-h-[90vh] overflow-y-auto">
        <DialogHeader>
          <DialogTitle className="flex items-center gap-2">
            <Mail className="h-5 w-5" />
            Email Team — {projectTitle}
          </DialogTitle>
          <DialogDescription>
            Compose a custom email to all members of this project&apos;s team.
            {recipientPreview.isLoading
              ? ' Loading recipients…'
              : ` Will be sent to ${recipientCount} team member${recipientCount === 1 ? '' : 's'}.`}
          </DialogDescription>
        </DialogHeader>

        <div className="space-y-4">
          <div className="space-y-2">
            <Label htmlFor="email-subject">Subject</Label>
            <Input
              id="email-subject"
              value={subject}
              onChange={(e) => setSubject(e.target.value)}
              placeholder="Subject of your email"
              maxLength={500}
            />
          </div>

          <div className="space-y-2">
            <Label htmlFor="email-body">Body</Label>
            <Textarea
              id="email-body"
              value={body}
              onChange={(e) => setBody(e.target.value)}
              rows={10}
              className="font-mono text-sm"
              placeholder={initialBody}
            />
            <p className="text-xs text-muted-foreground">
              The greeting is pre-filled — edit freely. The full email is wrapped in the standard
              MOPC styled template when sent. Click &quot;Show preview&quot; to see exactly what recipients will see.
            </p>
          </div>

          <div className="flex items-center gap-2">
            <Button
              type="button"
              variant="outline"
              size="sm"
              onClick={() => setShowPreview((s) => !s)}
              disabled={subject.length === 0 || body.length === 0}
            >
              <Eye className="mr-2 h-4 w-4" />
              {showPreview ? 'Hide preview' : 'Show preview'}
            </Button>
            <Button
              type="button"
              variant="outline"
              size="sm"
              onClick={() => sendTestMutation.mutate({ subject, body })}
              disabled={!canSend || sendTestMutation.isPending}
            >
              <Send className="mr-2 h-4 w-4" />
              {sendTestMutation.isPending ? 'Sending…' : 'Send test to me'}
            </Button>
          </div>

          {showPreview && emailPreview.data && (
            <div className="border rounded-md overflow-hidden">
              <div className="bg-muted text-xs px-3 py-2 border-b">Email preview</div>
              <iframe
                title="Email preview"
                srcDoc={emailPreview.data.html}
                className="w-full h-96 bg-white"
                sandbox=""
              />
            </div>
          )}
        </div>

        <DialogFooter>
          <Button variant="ghost" onClick={onClose}>Cancel</Button>
          <Button
            onClick={() =>
              sendMutation.mutate({
                recipientType: 'PROJECT_TEAM',
                recipientFilter: { projectId },
                subject,
                body,
                deliveryChannels: ['EMAIL'],
                linkType: 'NONE',
              })
            }
            disabled={!canSend || sendMutation.isPending}
          >
            <Send className="mr-2 h-4 w-4" />
            {sendMutation.isPending ? 'Sending…' : `Send to ${recipientCount}`}
          </Button>
        </DialogFooter>
      </DialogContent>
    </Dialog>
  )
}