import React, { useState } from 'react';
import { useApplications, useJobPostings, useScreenAllCandidates, useUpdateApplication } from '@/lib/krowHooks';
import { base44 } from '@/api/base44Client';
import CandidateCard from '@/components/krow/CandidateCard';
import AIInterviewModal from '@/components/krow/AIInterviewModal';
import ScheduleInterviewModal from '@/components/krow/ScheduleInterviewModal';
import MessageCandidateModal from '@/components/krow/MessageCandidateModal';
import { toast } from 'react-hot-toast';
import { AssistantTrigger } from '@/components/ai-assistant';

export default function Candidates() {
  const { data: applications = [], isLoading } = useApplications();
  const { data: postings = [] } = useJobPostings();
  const screenAll = useScreenAllCandidates();
  const [search, setSearch] = useState('');
  const [stageFilter, setStageFilter] = useState('all');
  const [scoreFilter, setScoreFilter] = useState('all');
  const [positionFilter, setPositionFilter] = useState('all');
  const [interviewApp, setInterviewApp] = useState(null);
  const [scheduleApp, setScheduleApp] = useState(null);
  const [messageApp, setMessageApp] = useState(null);
  const updateApp = useUpdateApplication();

  const handleDecline = async (app) => {
    try {
      await updateApp.mutateAsync({ id: app.id, data: { status: 'rejected' } });
      toast.success(`${app.applicant_name} declined`);
    } catch (e) {
      toast.error('Failed to decline candidate');
    }
  };

  const handleDelete = async (app) => {
    try {
      await base44.entities.JobApplication.delete(app.id);
      toast.success(`${app.applicant_name} deleted`);
    } catch (e) {
      toast.error('Failed to delete candidate');
    }
  };

  const postingById = Object.fromEntries(postings.map(p => [p.id, p]));
  const resolveTitle = (a) => a.job_title || postingById[a.job_posting_id]?.title || '';

  const sorted = [...applications].sort((a, b) => (b.ai_score || 0) - (a.ai_score || 0));

  const positionOptions = Array.from(new Set(applications.map(resolveTitle).filter(Boolean))).sort();

  const filtered = sorted.filter(a => {
    const title = resolveTitle(a).toLowerCase();
    const q = search.toLowerCase();
    const matchesSearch = !search ||
      a.applicant_name?.toLowerCase().includes(q) ||
      a.email?.toLowerCase().includes(q) ||
      title.includes(q);
    const matchesStage = stageFilter === 'all' || a.status === stageFilter;
    const matchesPosition = positionFilter === 'all' || resolveTitle(a) === positionFilter;
    const matchesScore = scoreFilter === 'all' ||
      (scoreFilter === 'high' && a.ai_score >= 80) ||
      (scoreFilter === 'mid' && a.ai_score >= 60 && a.ai_score < 80) ||
      (scoreFilter === 'low' && a.ai_score > 0 && a.ai_score < 60);
    return matchesSearch && matchesStage && matchesPosition && matchesScore;
  });

  const handleAction = (app) => {
    if (app.status === 'interview') {
      setInterviewApp(app);
    } else {
      setScheduleApp(app);
    }
  };

  const handleScreenAll = async () => {
    const unscreened = applications.filter(a => a.status === 'applied');
    if (unscreened.length === 0) {
      toast('All candidates have been screened');
      return;
    }
    const firstJob = postings.find(p => p.id === unscreened[0].job_posting_id);
    try {
      await screenAll.mutateAsync({ applications: unscreened, job: firstJob });
      toast.success(`Screened ${unscreened.length} candidates`);
    } catch (e) {
      toast.error('Screening failed');
    }
  };

  return (
    <div className="space-y-5">
      <div className="flex items-center justify-between">
        <div>
          <h1 className="text-[22px] font-bold text-[#111827]">All Candidates</h1>
        </div>
        <div className="flex items-center gap-3">
          <span className="text-[13px] text-[#6B7280]">{applications.length} candidates</span>
          <button
            onClick={handleScreenAll}
            disabled={screenAll.isPending}
            className="inline-flex items-center gap-1.5 bg-[#0A39DF] hover:bg-[#082EB4] disabled:opacity-50 text-white text-[13px] font-medium px-3 py-2 rounded-lg transition-colors"
          >
            {screenAll.isPending ? 'Screening...' : 'AI Screen All'}
          </button>
          <AssistantTrigger />
        </div>
      </div>

      {/* Filters */}
      <div className="flex flex-col sm:flex-row items-stretch sm:items-center gap-3">
        <div className="relative flex-1">
          <input
            value={search}
            onChange={(e) => setSearch(e.target.value)}
            placeholder="Search candidates..."
            className="w-full h-10 pl-4 pr-4 rounded-lg border border-[#E5E7EB] bg-white text-[13px] focus:border-[#0A39DF] focus:outline-none"
          />
        </div>
        <select value={stageFilter} onChange={(e) => setStageFilter(e.target.value)} className="h-10 px-4 rounded-lg border border-[#E5E7EB] bg-white text-[13px] focus:border-[#0A39DF] focus:outline-none">
          <option value="all">All Stages</option>
          <option value="applied">Applied</option>
          <option value="ai_screened">AI Screened</option>
          <option value="interview">Interviewing</option>
          <option value="hired">Hired</option>
        </select>
        <select value={positionFilter} onChange={(e) => setPositionFilter(e.target.value)} className="h-10 px-4 rounded-lg border border-[#E5E7EB] bg-white text-[13px] focus:border-[#0A39DF] focus:outline-none max-w-[200px] truncate">
          <option value="all">All Positions</option>
          {positionOptions.map(p => <option key={p} value={p}>{p}</option>)}
        </select>
        <select value={scoreFilter} onChange={(e) => setScoreFilter(e.target.value)} className="h-10 px-4 rounded-lg border border-[#E5E7EB] bg-white text-[13px] focus:border-[#0A39DF] focus:outline-none">
          <option value="all">All Scores</option>
          <option value="high">80+ (Top Talent)</option>
          <option value="mid">60-79 (Strong Fit)</option>
          <option value="low">0-59 (Possible/Not Fit)</option>
        </select>
      </div>

      {/* List */}
      {isLoading ? (
        <div className="space-y-3">
          {[...Array(5)].map((_, i) => <div key={i} className="h-20 bg-white border border-[#E5E7EB] rounded-xl animate-pulse" />)}
        </div>
      ) : filtered.length === 0 ? (
        <div className="text-center py-16">
          <p className="text-[14px] text-[#6B7280]">No candidates match your filters</p>
        </div>
      ) : (
        <div className="space-y-3">
          {filtered.map((app, idx) => (
            <CandidateCard
              key={app.id}
              application={app}
              jobTitle={resolveTitle(app)}
              rank={idx + 1}
              onAction={handleAction}
              onMessage={setMessageApp}
              onCall={setMessageApp}
              onSchedule={setScheduleApp}
              onDecline={handleDecline}
              onDelete={handleDelete}
            />
          ))}
        </div>
      )}

      {/* Modals */}
      {interviewApp && (
        <AIInterviewModal open={true} onClose={() => setInterviewApp(null)} application={interviewApp} job={postings.find(p => p.id === interviewApp.job_posting_id)} />
      )}
      {scheduleApp && (
        <ScheduleInterviewModal open={true} onClose={() => setScheduleApp(null)} application={scheduleApp} />
      )}
      {messageApp && (
        <MessageCandidateModal open={true} onClose={() => setMessageApp(null)} application={messageApp} />
      )}
    </div>
  );
}