import React, { useState } from "react";
import { base44 } from "@/api/base44Client";
import { useQuery } from "@tanstack/react-query";
import { Card, CardHeader, CardTitle, CardContent } from "@/components/ui/card";
import { Button } from "@/components/ui/button";
import { Tabs, TabsList, TabsTrigger } from "@/components/ui/tabs";
import { MessageSquare, Plus, Users } from "lucide-react";
import ConversationList from "@/components/messaging/ConversationList";
import MessageThread from "@/components/messaging/MessageThread";
import MessageInput from "@/components/messaging/MessageInput";
import {
  Dialog,
  DialogContent,
  DialogHeader,
  DialogTitle,
  DialogFooter,
} from "@/components/ui/dialog";
import { Input } from "@/components/ui/input";
import { Label } from "@/components/ui/label";
import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select";
import { Badge } from "@/components/ui/badge";
import PageHeader from "@/components/common/PageHeader";

export default function Messages() {
  const [selectedConversation, setSelectedConversation] = useState(null);
  const [activeTab, setActiveTab] = useState("all");
  const [showNewConversation, setShowNewConversation] = useState(false);
  const [conversationMode, setConversationMode] = useState("individual");
  const [newConvData, setNewConvData] = useState({
    type: "client-vendor",
    subject: "",
    participant_id: "",
    participant_name: "",
    participant_role: "client",
    group_type: "all-active-staff",
    event_id: ""
  });

  const { data: user } = useQuery({
    queryKey: ['current-user'],
    queryFn: () => base44.auth.me(),
  });

  const { data: staff } = useQuery({
    queryKey: ['staff-list'],
    queryFn: () => base44.entities.Staff.list(),
    initialData: [],
  });

  const { data: businesses } = useQuery({
    queryKey: ['businesses-list'],
    queryFn: () => base44.entities.Business.list(),
    initialData: [],
  });

  const { data: events } = useQuery({
    queryKey: ['events-list'],
    queryFn: () => base44.entities.Event.list('-date'),
    initialData: [],
  });

  const { data: conversations, refetch: refetchConversations } = useQuery({
    queryKey: ['conversations'],
    queryFn: () => base44.entities.Conversation.list('-last_message_at'),
    initialData: [],
  });

  const { data: messages, refetch: refetchMessages } = useQuery({
    queryKey: ['messages', selectedConversation?.id],
    queryFn: () => base44.entities.Message.filter({ conversation_id: selectedConversation?.id }),
    initialData: [],
    enabled: !!selectedConversation?.id
  });

  const filteredConversations = conversations.filter(conv => {
    if (activeTab === "all") return conv.status === "active";
    if (activeTab === "groups") return conv.is_group && conv.status === "active";
    return conv.conversation_type === activeTab && conv.status === "active";
  });

  const getAvailableParticipants = () => {
    const convType = newConvData.type;
    
    if (convType === "client-vendor" || convType === "client-admin") {
      return businesses.map(b => ({
        id: b.id,
        name: b.business_name,
        role: "client",
        contact: b.contact_name
      }));
    } else if (convType === "staff-client" || convType === "staff-admin") {
      return staff.map(s => ({
        id: s.id,
        name: s.employee_name,
        role: "staff",
        position: s.position
      }));
    } else if (convType === "vendor-admin") {
      return businesses.map(b => ({
        id: b.id,
        name: b.business_name,
        role: "vendor",
        contact: b.contact_name
      }));
    }
    
    return [];
  };

  const handleParticipantSelect = (participantId) => {
    const participants = getAvailableParticipants();
    const selected = participants.find(p => p.id === participantId);
    
    if (selected) {
      setNewConvData({
        ...newConvData,
        participant_id: selected.id,
        participant_name: selected.name,
        participant_role: selected.role
      });
    }
  };

  const getGroupParticipants = () => {
    if (newConvData.group_type === "all-active-staff") {
      return staff.map(s => ({
        id: s.id,
        name: s.employee_name,
        role: "staff"
      }));
    } else if (newConvData.group_type === "event-staff" && newConvData.event_id) {
      const event = events.find(e => e.id === newConvData.event_id);
      if (event && event.assigned_staff) {
        return event.assigned_staff.map(s => ({
          id: s.staff_id,
          name: s.staff_name,
          role: "staff"
        }));
      }
    }
    return [];
  };

  const handleCreateConversation = async () => {
    if (!newConvData.subject) return;

    let participants = [];
    let conversationType = "";
    let groupName = "";
    let isGroup = false;
    let relatedTo = null;
    let relatedType = null;

    if (conversationMode === "individual") {
      if (!newConvData.participant_id) return;
      
      participants = [
        { id: user?.id, name: user?.full_name || user?.email, role: "admin" },
        { 
          id: newConvData.participant_id, 
          name: newConvData.participant_name, 
          role: newConvData.participant_role 
        }
      ];
      conversationType = newConvData.type;
    } else {
      const groupParticipants = getGroupParticipants();
      if (groupParticipants.length === 0) return;

      participants = [
        { id: user?.id, name: user?.full_name || user?.email, role: "admin" },
        ...groupParticipants
      ];
      
      isGroup = true;
      
      if (newConvData.group_type === "all-active-staff") {
        conversationType = "group-staff";
        groupName = "All Active Staff";
      } else if (newConvData.group_type === "event-staff") {
        conversationType = "group-event-staff";
        const event = events.find(e => e.id === newConvData.event_id);
        groupName = event ? `${event.event_name} Team` : "Event Team";
        relatedTo = newConvData.event_id;
        relatedType = "event";
      }
    }

    const newConv = await base44.entities.Conversation.create({
      participants,
      conversation_type: conversationType,
      is_group: isGroup,
      group_name: groupName,
      subject: newConvData.subject,
      status: "active",
      related_to: relatedTo,
      related_type: relatedType
    });

    setShowNewConversation(false);
    setConversationMode("individual");
    setNewConvData({ 
      type: "client-vendor", 
      subject: "", 
      participant_id: "",
      participant_name: "",
      participant_role: "client",
      group_type: "all-active-staff",
      event_id: ""
    });
    refetchConversations();
    setSelectedConversation(newConv);
  };

  const availableParticipants = getAvailableParticipants();
  const groupParticipants = conversationMode === "group" ? getGroupParticipants() : [];

  return (
    <div className="p-4 md:p-8 bg-slate-50 min-h-screen">
      <div className="max-w-7xl mx-auto">
        <PageHeader 
          title="Messages"
          subtitle="Communicate with your team, vendors, and clients"
          icon={MessageSquare}
        >
          <Button onClick={() => setShowNewConversation(true)} className="bg-[#0A39DF] hover:bg-[#0A39DF]/90">
            <Plus className="w-4 h-4 mr-2" />
            New Conversation
          </Button>
        </PageHeader>

        <Tabs value={activeTab} onValueChange={setActiveTab} className="mb-6">
          <TabsList className="bg-white border border-slate-200">
            <TabsTrigger value="all">All</TabsTrigger>
            <TabsTrigger value="groups">
              <Users className="w-4 h-4 mr-2" />
              Groups
            </TabsTrigger>
            <TabsTrigger value="client-vendor">Client ↔ Vendor</TabsTrigger>
            <TabsTrigger value="staff-client">Staff ↔ Client</TabsTrigger>
            <TabsTrigger value="staff-admin">Staff ↔ Admin</TabsTrigger>
          </TabsList>
        </Tabs>

        <div className="grid grid-cols-1 lg:grid-cols-3 gap-6">
          <Card className="lg:col-span-1 border-slate-200">
            <CardHeader className="bg-gradient-to-br from-slate-50 to-white border-b">
              <CardTitle className="text-base">Conversations</CardTitle>
            </CardHeader>
            <CardContent className="p-4 max-h-[600px] overflow-y-auto">
              <ConversationList
                conversations={filteredConversations}
                selectedId={selectedConversation?.id}
                onSelect={setSelectedConversation}
              />
            </CardContent>
          </Card>

          <Card className="lg:col-span-2 border-slate-200">
            {selectedConversation ? (
              <>
                <CardHeader className="bg-gradient-to-br from-slate-50 to-white border-b">
                  <div>
                    <div className="flex items-center gap-2 mb-1">
                      <CardTitle>{selectedConversation.subject}</CardTitle>
                      {selectedConversation.is_group && (
                        <Badge className="bg-purple-100 text-purple-700">
                          <Users className="w-3 h-3 mr-1" />
                          Group
                        </Badge>
                      )}
                    </div>
                    {selectedConversation.is_group ? (
                      <p className="text-sm text-slate-500 mt-1">
                        {selectedConversation.group_name} • {selectedConversation.participants?.length || 0} members
                      </p>
                    ) : (
                      <p className="text-sm text-slate-500 mt-1">
                        {selectedConversation.participants?.map(p => p.name).join(', ')}
                      </p>
                    )}
                  </div>
                </CardHeader>
                <CardContent className="p-0">
                  <MessageThread messages={messages} currentUserId={user?.id} />
                  <MessageInput
                    conversationId={selectedConversation.id}
                    currentUser={user}
                    onMessageSent={() => {
                      refetchMessages();
                      refetchConversations();
                    }}
                  />
                </CardContent>
              </>
            ) : (
              <div className="flex items-center justify-center h-full min-h-[400px]">
                <div className="text-center">
                  <MessageSquare className="w-16 h-16 mx-auto text-slate-300 mb-4" />
                  <p className="text-slate-500">Select a conversation to start messaging</p>
                </div>
              </div>
            )}
          </Card>
        </div>
      </div>

      <Dialog open={showNewConversation} onOpenChange={setShowNewConversation}>
        <DialogContent className="max-w-2xl">
          <DialogHeader>
            <DialogTitle>New Conversation</DialogTitle>
          </DialogHeader>
          <div className="space-y-4">
            <div>
              <Label className="mb-3 block font-semibold">Conversation Mode</Label>
              <div className="flex gap-3">
                <button
                  onClick={() => setConversationMode("individual")}
                  className={`flex-1 flex items-center space-x-3 p-4 rounded-lg border-2 cursor-pointer transition-all ${
                    conversationMode === "individual" 
                      ? 'border-[#0A39DF] bg-blue-50' 
                      : 'border-slate-200 bg-white hover:border-slate-300'
                  }`}
                >
                  <div className={`w-4 h-4 rounded-full border-2 flex items-center justify-center ${
                    conversationMode === "individual" ? 'border-[#0A39DF]' : 'border-slate-300'
                  }`}>
                    {conversationMode === "individual" && (
                      <div className="w-2 h-2 rounded-full bg-[#0A39DF]" />
                    )}
                  </div>
                  <div className="flex-1 text-left">
                    <div className="flex items-center gap-2">
                      <MessageSquare className="w-4 h-4" />
                      <span className="font-semibold">Individual</span>
                    </div>
                    <p className="text-xs text-slate-500 mt-1">One-on-one conversation</p>
                  </div>
                </button>

                <button
                  onClick={() => setConversationMode("group")}
                  className={`flex-1 flex items-center space-x-3 p-4 rounded-lg border-2 cursor-pointer transition-all ${
                    conversationMode === "group" 
                      ? 'border-[#0A39DF] bg-blue-50' 
                      : 'border-slate-200 bg-white hover:border-slate-300'
                  }`}
                >
                  <div className={`w-4 h-4 rounded-full border-2 flex items-center justify-center ${
                    conversationMode === "group" ? 'border-[#0A39DF]' : 'border-slate-300'
                  }`}>
                    {conversationMode === "group" && (
                      <div className="w-2 h-2 rounded-full bg-[#0A39DF]" />
                    )}
                  </div>
                  <div className="flex-1 text-left">
                    <div className="flex items-center gap-2">
                      <Users className="w-4 h-4" />
                      <span className="font-semibold">Group Chat</span>
                    </div>
                    <p className="text-xs text-slate-500 mt-1">Message multiple people</p>
                  </div>
                </button>
              </div>
            </div>

            {conversationMode === "individual" ? (
              <>
                <div>
                  <Label>Conversation Type</Label>
                  <Select 
                    value={newConvData.type} 
                    onValueChange={(v) => setNewConvData({
                      ...newConvData, 
                      type: v,
                      participant_id: "",
                      participant_name: ""
                    })}
                  >
                    <SelectTrigger>
                      <SelectValue />
                    </SelectTrigger>
                    <SelectContent>
                      <SelectItem value="client-vendor">Client ↔ Vendor</SelectItem>
                      <SelectItem value="staff-client">Staff ↔ Client</SelectItem>
                      <SelectItem value="staff-admin">Staff ↔ Admin</SelectItem>
                      <SelectItem value="vendor-admin">Vendor ↔ Admin</SelectItem>
                    </SelectContent>
                  </Select>
                </div>
                
                <div>
                  <Label>Select {newConvData.type.includes('client') ? 'Client' : newConvData.type.includes('staff') ? 'Staff' : 'Vendor'}</Label>
                  <Select 
                    value={newConvData.participant_id} 
                    onValueChange={handleParticipantSelect}
                  >
                    <SelectTrigger>
                      <SelectValue placeholder={`Choose a ${newConvData.type.includes('client') ? 'client' : newConvData.type.includes('staff') ? 'staff member' : 'vendor'}`} />
                    </SelectTrigger>
                    <SelectContent>
                      {availableParticipants.length > 0 ? (
                        availableParticipants.map((participant) => (
                          <SelectItem key={participant.id} value={participant.id}>
                            <div className="flex flex-col">
                              <span className="font-medium">{participant.name}</span>
                              {participant.position && (
                                <span className="text-xs text-slate-500">{participant.position}</span>
                              )}
                              {participant.contact && (
                                <span className="text-xs text-slate-500">Contact: {participant.contact}</span>
                              )}
                            </div>
                          </SelectItem>
                        ))
                      ) : (
                        <SelectItem value="none" disabled>
                          No {newConvData.type.includes('client') ? 'clients' : newConvData.type.includes('staff') ? 'staff' : 'vendors'} available
                        </SelectItem>
                      )}
                    </SelectContent>
                  </Select>
                </div>
              </>
            ) : (
              <>
                <div>
                  <Label>Group Type</Label>
                  <Select 
                    value={newConvData.group_type} 
                    onValueChange={(v) => setNewConvData({...newConvData, group_type: v, event_id: ""})}
                  >
                    <SelectTrigger>
                      <SelectValue />
                    </SelectTrigger>
                    <SelectContent>
                      <SelectItem value="all-active-staff">
                        <div className="flex flex-col">
                          <span className="font-medium">All Active Staff</span>
                          <span className="text-xs text-slate-500">{staff.length} members</span>
                        </div>
                      </SelectItem>
                      <SelectItem value="event-staff">
                        <div className="flex flex-col">
                          <span className="font-medium">Event Staff Team</span>
                          <span className="text-xs text-slate-500">Select staff assigned to an event</span>
                        </div>
                      </SelectItem>
                    </SelectContent>
                  </Select>
                </div>

                {newConvData.group_type === "event-staff" && (
                  <div>
                    <Label>Select Event</Label>
                    <Select 
                      value={newConvData.event_id} 
                      onValueChange={(v) => setNewConvData({...newConvData, event_id: v})}
                    >
                      <SelectTrigger>
                        <SelectValue placeholder="Choose an event" />
                      </SelectTrigger>
                      <SelectContent>
                        {events.filter(e => e.assigned_staff && e.assigned_staff.length > 0).map((event) => (
                          <SelectItem key={event.id} value={event.id}>
                            <div className="flex flex-col">
                              <span className="font-medium">{event.event_name}</span>
                              <span className="text-xs text-slate-500">
                                {event.assigned_staff?.length || 0} staff assigned
                              </span>
                            </div>
                          </SelectItem>
                        ))}
                      </SelectContent>
                    </Select>
                  </div>
                )}

                {groupParticipants.length > 0 && (
                  <div className="bg-slate-50 p-4 rounded-lg">
                    <Label className="text-sm font-semibold mb-2 block">
                      Group Members ({groupParticipants.length})
                    </Label>
                    <div className="flex flex-wrap gap-2 max-h-32 overflow-y-auto">
                      {groupParticipants.map((p) => (
                        <Badge key={p.id} variant="outline" className="bg-white">
                          {p.name}
                        </Badge>
                      ))}
                    </div>
                  </div>
                )}
              </>
            )}

            <div>
              <Label>Subject</Label>
              <Input
                placeholder={conversationMode === "group" ? "e.g., Team Announcement" : "e.g., Order #12345 Discussion"}
                value={newConvData.subject}
                onChange={(e) => setNewConvData({...newConvData, subject: e.target.value})}
              />
            </div>
          </div>
          <DialogFooter>
            <Button variant="outline" onClick={() => setShowNewConversation(false)}>Cancel</Button>
            <Button 
              onClick={handleCreateConversation} 
              className="bg-[#0A39DF]"
              disabled={
                !newConvData.subject || 
                (conversationMode === "individual" && !newConvData.participant_id) ||
                (conversationMode === "group" && groupParticipants.length === 0)
              }
            >
              Create
            </Button>
          </DialogFooter>
        </DialogContent>
      </Dialog>
    </div>
  );
}