import React, { useCallback, useEffect, useMemo, useState } from 'react';
import {
  Activity, RefreshCw, CheckCircle, AlertCircle, Square, Circle,
  Trash2, Download, XCircle, Film, Globe,
} from 'lucide-react';
import { Panel, Button, Badge, Tabs } from '../ui';
import {
  listBatchJobs, cancelBatchJob, deleteBatchJob, enqueueBatchJob,
} from '../api/batch';
import { API } from '../api/client';
import BatchAddDialog from '../components/BatchAddDialog';
import toast from 'react-hot-toast';
import './BatchQueue.css';

/**
 * BatchQueue — UI for the /batch/* dubbing pipeline.
 *
 * Tabs: Active · Done · Failed. Polls every 3s for active jobs.
 * Shows real-time progress (extract → transcribe → translate → generate → mix).
 */
const TABS = [
  { id: 'active',   label: 'Active',    icon: Activity     },
  { id: 'done',     label: 'Completed', icon: CheckCircle },
  { id: 'failed',   label: 'Failed',    icon: AlertCircle  },
];

const STATUS_TONE = {
  queued:    { tone: 'neutral', icon: Circle,      label: 'queued'    },
  running:   { tone: 'brand',   icon: Activity,    label: 'running'   },
  done:      { tone: 'success', icon: CheckCircle, label: 'done'      },
  failed:    { tone: 'danger',  icon: AlertCircle, label: 'failed'    },
  cancelled: { tone: 'warn',    icon: Square,      label: 'cancelled' },
};

const STAGE_LABELS = {
  extract:    '🎬 Extracting audio…',
  transcribe: '📝 Transcribing…',
  translate:  '🌐 Translating…',
  generate:   '🗣️ Generating speech…',
  mix:        '🎛️ Mixing audio…',
  done:       '✅ Complete',
};

export default function BatchQueue({ onBack }) {
  const [tab, setTab] = useState('active');
  const [jobs, setJobs] = useState([]);
  const [loading, setLoading] = useState(false);
  const [addOpen, setAddOpen] = useState(false);

  const reload = useCallback(async () => {
    setLoading(true);
    try {
      const statusParam = tab === 'active' ? 'active' : tab;
      setJobs(await listBatchJobs(statusParam, 100));
    } catch (e) {
      console.warn('batch queue load failed', e);
    } finally {
      setLoading(false);
    }
  }, [tab]);

  useEffect(() => { reload(); }, [reload]);

  // Poll active tab every 3s for live progress
  useEffect(() => {
    if (tab !== 'active') return;
    const iv = setInterval(reload, 3000);
    return () => clearInterval(iv);
  }, [tab, reload]);

  const handleEnqueue = useCallback(async (files, settings) => {
    const langCodes = settings.langs.map(l => l.code);
    let success = 0;
    for (const file of files) {
      try {
        await enqueueBatchJob(file, langCodes, settings.voiceId || undefined, settings.preserveBg);
        success++;
      } catch (e) {
        toast.error(`Failed to enqueue ${file.name}: ${e.message}`);
      }
    }
    if (success > 0) {
      toast.success(`${success} video${success > 1 ? 's' : ''} added to queue`);
      setTab('active');
      reload();
    }
  }, [reload]);

  const handleCancel = useCallback(async (id) => {
    try {
      await cancelBatchJob(id);
      toast.success('Job cancelled');
      reload();
    } catch (e) {
      toast.error('Cancel failed: ' + e.message);
    }
  }, [reload]);

  const handleDelete = useCallback(async (id) => {
    try {
      await deleteBatchJob(id);
      toast.success('Job deleted');
      reload();
    } catch (e) {
      toast.error('Delete failed: ' + e.message);
    }
  }, [reload]);

  return (
    <div className="batch-queue">
      <div className="batch-queue__bar">
        {onBack && <Button variant="ghost" size="sm" onClick={onBack}>← Back</Button>}
        <h1><Activity size={15} /> Batch dubbing</h1>
        <div className="batch-queue__bar-spacer" />
        <Button variant="subtle" size="sm" onClick={reload} loading={loading} leading={<RefreshCw size={11} />}>
          Refresh
        </Button>
        <Button variant="primary" size="sm" onClick={() => setAddOpen(true)} leading={<PlusIcon size={11} />}>
          Add Videos
        </Button>
      </div>

      <Tabs
        items={TABS}
        value={tab}
        onChange={setTab}
        className="batch-queue__tabs"
      />

      {jobs.length === 0 && !loading && (
        <Panel variant="flat" padding="lg" className="batch-queue__empty">
          <div>
            <p>No {tab} jobs.</p>
            <p className="batch-queue__empty-sub">
              {tab === 'active' && 'Drop videos above to start batch dubbing.'}
              {tab === 'done' && 'Nothing has completed recently.'}
              {tab === 'failed' && 'No failed jobs — enjoy the silence.'}
            </p>
          </div>
        </Panel>
      )}

      <div className="batch-queue__list">
        {jobs.map(j => (
          <JobCard
            key={j.id}
            job={j}
            onCancel={handleCancel}
            onDelete={handleDelete}
          />
        ))}
      </div>

      <BatchAddDialog
        open={addOpen}
        onClose={() => setAddOpen(false)}
        onEnqueue={handleEnqueue}
      />
    </div>
  );
}

function PlusIcon({ size }) {
  return (
    <svg width={size} height={size} viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round">
      <line x1="12" y1="5" x2="12" y2="19" />
      <line x1="5" y1="12" x2="19" y2="12" />
    </svg>
  );
}

function JobCard({ job, onCancel, onDelete }) {
  const st = STATUS_TONE[job.status] || STATUS_TONE.queued;
  const StIcon = st.icon;

  const ageLabel = formatAge((Date.now() / 1000 - (job.created_at || 0)) * 1000);

  const duration = job.finished_at && job.started_at
    ? Math.max(0, job.finished_at - job.started_at)
    : null;

  const progress = job.progress;
  const stageLabel = progress ? (STAGE_LABELS[progress.stage] || progress.stage) : null;
  const pct = progress?.percent ?? 0;

  return (
    <Panel variant="flat" padding="md" className={`batch-queue__card batch-queue__card--${job.status}`}>
      <div className="batch-queue__card-head">
        <Badge tone={st.tone} dot>
          <StIcon size={10} /> {st.label}
        </Badge>
        <span className="batch-queue__card-filename">
          <Film size={10} /> {job.filename}
        </span>
        <span className="batch-queue__card-spacer" />
        <span className="batch-queue__card-age" title={new Date((job.created_at || 0) * 1000).toLocaleString()}>
          {ageLabel}
        </span>
      </div>

      {/* Languages */}
      <div className="batch-queue__card-langs">
        <Globe size={9} />
        {job.langs.map(l => (
          <span key={l} className="batch-queue__card-lang">{l}</span>
        ))}
      </div>

      {/* Progress bar for running jobs */}
      {job.status === 'running' && progress && (
        <div className="batch-queue__progress">
          <div className="batch-queue__progress-bar">
            <div
              className="batch-queue__progress-fill"
              style={{ width: `${Math.min(100, pct)}%` }}
            />
          </div>
          <div className="batch-queue__progress-info">
            <span className="batch-queue__progress-stage">{stageLabel}</span>
            {progress.current_lang && (
              <span className="batch-queue__progress-lang">{progress.current_lang}</span>
            )}
            {progress.current_segment != null && progress.total_segments && (
              <span className="batch-queue__progress-segs">
                seg {progress.current_segment}/{progress.total_segments}
              </span>
            )}
            <span className="batch-queue__progress-pct">{pct}%</span>
          </div>
        </div>
      )}

      {/* Duration for completed jobs */}
      {duration != null && (
        <div className="batch-queue__card-meta">
          Completed in {formatDuration(duration)}
        </div>
      )}

      {/* Error display */}
      {job.error && (
        <div className="batch-queue__card-error">
          <AlertCircle size={11} /> {job.error}
        </div>
      )}

      {/* Output downloads for done jobs */}
      {job.status === 'done' && job.outputs && Object.keys(job.outputs).length > 0 && (
        <div className="batch-queue__card-outputs">
          {Object.entries(job.outputs).map(([lang, path]) => (
            <a
              key={lang}
              className="batch-queue__card-dl"
              href={`${API}/batch/download/${job.id}/${lang}`}
              download
            >
              <Download size={10} /> {lang}
            </a>
          ))}
        </div>
      )}

      {/* Actions */}
      <div className="batch-queue__card-actions">
        {(job.status === 'queued' || job.status === 'running') && (
          <Button variant="ghost" size="xs" onClick={() => onCancel(job.id)} leading={<XCircle size={10} />}>
            Cancel
          </Button>
        )}
        {(job.status === 'done' || job.status === 'failed' || job.status === 'cancelled') && (
          <Button variant="ghost" size="xs" onClick={() => onDelete(job.id)} leading={<Trash2 size={10} />}>
            Delete
          </Button>
        )}
      </div>
    </Panel>
  );
}

function formatAge(ms) {
  if (!isFinite(ms) || ms < 0) return '—';
  const s = Math.floor(ms / 1000);
  if (s < 60) return `${s}s ago`;
  const m = Math.floor(s / 60);
  if (m < 60) return `${m}m ago`;
  const h = Math.floor(m / 60);
  if (h < 24) return `${h}h ago`;
  return new Date(Date.now() - ms).toLocaleDateString();
}

function formatDuration(secs) {
  if (secs < 60) return `${secs.toFixed(1)}s`;
  const m = Math.floor(secs / 60);
  const s = Math.round(secs % 60);
  if (m < 60) return `${m}m ${s}s`;
  const h = Math.floor(m / 60);
  return `${h}h ${m % 60}m`;
}