'use client';

import { useEffect, useState } from 'react';
import { ListTodo, Send, Loader2, RefreshCw, Clock, CheckCircle2, XCircle, Zap, AlertTriangle } from 'lucide-react';
import { api, type QueueJob, type QueueStatus } from '@/lib/api';

const PRIORITY_LABELS = ['CRITICAL', 'HIGH', 'NORMAL', 'LOW'];
const PRIORITY_COLORS = [
  'bg-red-500/20 text-red-300 border-red-500/30',
  'bg-orange-500/20 text-orange-300 border-orange-500/30',
  'bg-blue-500/20 text-blue-300 border-blue-500/30',
  'bg-slate-500/20 text-slate-300 border-slate-500/30',
];

function PriorityBadge({ priority }: { priority: number }) {
  const cls = PRIORITY_COLORS[priority] ?? PRIORITY_COLORS[2];
  return (
    <span className={`inline-flex items-center rounded border px-2 py-0.5 text-[10px] font-bold ${cls}`}>
      {PRIORITY_LABELS[priority] ?? 'NORMAL'}
    </span>
  );
}

function JobStatusIcon({ status }: { status: string }) {
  if (status === 'COMPLETE') return <CheckCircle2 className="h-4 w-4 text-emerald-400" />;
  if (status === 'FAILED') return <XCircle className="h-4 w-4 text-red-400" />;
  if (status === 'RUNNING') return <Loader2 className="h-4 w-4 text-blue-400 animate-spin" />;
  if (status === 'CANCELLED') return <XCircle className="h-4 w-4 text-orange-400" />;
  return <Clock className="h-4 w-4 text-slate-400" />;
}

export default function QueuePanel() {
  const [status, setStatus] = useState<QueueStatus | null>(null);
  const [jobs, setJobs] = useState<QueueJob[]>([]);
  const [loading, setLoading] = useState(false);
  const [err, setErr] = useState<string | null>(null);

  // Submit form
  const [prompt, setPrompt] = useState('');
  const [priority, setPriority] = useState(2);
  const [submitting, setSubmitting] = useState(false);

  const reload = async () => {
    setLoading(true);
    try {
      const [st, jb] = await Promise.all([api.queueStatus(), api.listQueueJobs()]);
      setStatus(st);
      setJobs(jb.jobs);
      setErr(null);
    } catch (e: any) {
      setErr(e.message);
    } finally {
      setLoading(false);
    }
  };

  useEffect(() => {
    reload();
    const t = setInterval(reload, 3000);
    return () => clearInterval(t);
  }, []);

  const submit = async (e: React.FormEvent) => {
    e.preventDefault();
    if (!prompt.trim()) return;
    setSubmitting(true);
    try {
      const title = prompt.split('\n')[0].slice(0, 80);
      await api.queueSubmit(title, prompt, priority);
      setPrompt('');
      await reload();
    } catch (e: any) {
      setErr(e.message);
    } finally {
      setSubmitting(false);
    }
  };

  return (
    <div className="space-y-6">
      {/* Stats row */}
      <div className="grid grid-cols-2 sm:grid-cols-3 gap-4">
        <div className="rounded-xl border border-white/10 bg-slate-900/60 p-4">
          <p className="text-xs text-slate-400 uppercase tracking-wide mb-1">Queue Depth</p>
          <p className="text-3xl font-bold">{status?.queue_depth ?? '—'}</p>
        </div>
        <div className="rounded-xl border border-white/10 bg-slate-900/60 p-4">
          <p className="text-xs text-slate-400 uppercase tracking-wide mb-1">Running</p>
          <p className="text-3xl font-bold text-blue-300">{status?.running_jobs ?? '—'}</p>
        </div>
        <div className="rounded-xl border border-white/10 bg-slate-900/60 p-4">
          <p className="text-xs text-slate-400 uppercase tracking-wide mb-1">Backend</p>
          <div className="flex items-center gap-2 mt-1">
            <Zap className="h-4 w-4 text-brand-400" />
            <span className="font-semibold capitalize">{status?.backend ?? '—'}</span>
          </div>
        </div>
      </div>

      {/* Submit to queue */}
      <section className="rounded-xl border border-white/10 bg-slate-900/60 p-5">
        <h2 className="flex items-center gap-2 font-semibold mb-4">
          <ListTodo className="h-4 w-4 text-brand-400" />
          Submit to Queue
        </h2>
        <form onSubmit={submit} className="space-y-3">
          <textarea
            value={prompt}
            onChange={e => setPrompt(e.target.value)}
            rows={3}
            placeholder="Describe the task to queue..."
            className="w-full rounded-lg border border-white/10 bg-slate-800/60 p-3 text-sm focus:outline-none focus:ring-2 focus:ring-brand-500"
          />
          <div className="flex items-center gap-3 flex-wrap">
            <div className="flex items-center gap-2">
              <label className="text-xs text-slate-400">Priority:</label>
              <select
                value={priority}
                onChange={e => setPriority(Number(e.target.value))}
                className="text-xs bg-slate-700 border border-slate-600 text-slate-200 rounded px-2 py-1 focus:outline-none"
              >
                <option value={0}>0 — CRITICAL</option>
                <option value={1}>1 — HIGH</option>
                <option value={2}>2 — NORMAL</option>
                <option value={3}>3 — LOW</option>
              </select>
            </div>
            <button
              type="submit"
              disabled={submitting || !prompt.trim()}
              className="flex items-center gap-2 rounded-lg bg-brand-600 px-4 py-2 text-sm font-medium hover:bg-brand-700 disabled:opacity-50 ml-auto"
            >
              {submitting ? <Loader2 className="h-4 w-4 animate-spin" /> : <Send className="h-4 w-4" />}
              Queue Task
            </button>
          </div>
        </form>
      </section>

      {/* Error */}
      {err && (
        <div className="flex items-center gap-2 rounded-lg bg-red-500/10 border border-red-500/20 p-3 text-sm text-red-300">
          <AlertTriangle className="h-4 w-4 shrink-0" /> {err}
        </div>
      )}

      {/* Queued jobs */}
      <section className="rounded-xl border border-white/10 bg-slate-900/60 p-5">
        <header className="flex items-center justify-between mb-4">
          <h2 className="flex items-center gap-2 font-semibold">
            <ListTodo className="h-4 w-4 text-slate-400" />
            Queued Jobs
            {jobs.length > 0 && (
              <span className="ml-1 text-xs bg-slate-700 text-slate-300 px-2 py-0.5 rounded-full">{jobs.length}</span>
            )}
          </h2>
          <button
            onClick={reload}
            className="flex items-center gap-1 text-xs text-slate-400 hover:text-slate-200 border border-white/10 rounded px-2 py-1 hover:bg-white/5"
          >
            <RefreshCw className={`h-3 w-3 ${loading ? 'animate-spin' : ''}`} />
            Refresh
          </button>
        </header>

        {jobs.length === 0 ? (
          <p className="text-sm text-slate-500 italic">No jobs in queue.</p>
        ) : (
          <div className="space-y-2">
            {jobs.map(job => (
              <div key={job.job_id} className="flex items-start gap-3 rounded-lg border border-white/5 bg-slate-800/40 p-3">
                <JobStatusIcon status={job.status} />
                <div className="flex-1 min-w-0">
                  <div className="flex items-center gap-2 flex-wrap">
                    <span className="font-mono text-xs text-slate-500">#{job.task_id}</span>
                    <PriorityBadge priority={job.priority} />
                    <span className="text-xs text-slate-400 truncate">{job.prompt.slice(0, 60)}</span>
                  </div>
                  <p className="text-[10px] text-slate-600 mt-0.5">
                    job: {job.job_id} · status: {job.status}
                    {job.retry_count > 0 && ` · retries: ${job.retry_count}`}
                  </p>
                </div>
              </div>
            ))}
          </div>
        )}
      </section>
    </div>
  );
}