import {useEffect,useState,type ReactNode} from 'react';
import {Download,Link,Play,Server,Square} from 'lucide-react';
import {Badge,Button,ProgressBar,PropertyRow,Select} from '../../components/ui';
import {LocalTrainingClient} from '../../training/LocalTrainingClient';
import type {TrainingDevice,TrainingJob,TrainingServerInfo,WandbMode} from '../../training/types';

const ENDPOINT_KEY='mujoco-local-training-endpoint',JOB_KEY='mujoco-local-training-job';
const DEFAULT_ENDPOINT='http://127.0.0.1:8765';
const ACTIVE_STATES=new Set(['queued','running']);
function stored(key:string,fallback=''):string{try{return localStorage.getItem(key)??fallback;}catch{return fallback;}}
function errorText(error:unknown):string{return error instanceof Error?error.message:String(error);}
function stateLabel(state:TrainingJob['state']):string{return {queued:'排队中',running:'训练中',succeeded:'已完成',failed:'失败',cancelled:'已取消'}[state];}

export function LocalTrainingPanel({onPolicyReady}:{onPolicyReady(file:File):void}){
  const [endpoint,setEndpoint]=useState(()=>stored(ENDPOINT_KEY,DEFAULT_ENDPOINT));
  const [server,setServer]=useState<TrainingServerInfo>();
  const [job,setJob]=useState<TrainingJob>();
  const [busy,setBusy]=useState(false),[error,setError]=useState<string>();
  const [taskId,setTaskId]=useState('Unitree-Go2-Flat'),[numEnvs,setNumEnvs]=useState(4096),[maxIterations,setMaxIterations]=useState(2000),[seed,setSeed]=useState(42),[runName,setRunName]=useState('web'),[device,setDevice]=useState<TrainingDevice>('gpu'),[gpuIds,setGpuIds]=useState('0'),[wandbMode,setWandbMode]=useState<WandbMode>('offline');

  const connect=async()=>{
    setBusy(true);setError(undefined);
    try{
      const client=new LocalTrainingClient(endpoint),info=await client.health();
      setServer(info);try{localStorage.setItem(ENDPOINT_KEY,client.endpoint);}catch{/* 当前会话仍可连接 */}
      if(info.tasks.length&&!info.tasks.includes(taskId))setTaskId(info.tasks[0]);
      const remembered=info.activeJobId??stored(JOB_KEY);
      if(remembered){try{setJob(await client.job(remembered));}catch{try{localStorage.removeItem(JOB_KEY);}catch{/* ignore */}}}
      if(!info.ready)setError(info.error??'训练服务尚未就绪');
    }catch(value){setServer(undefined);setError(errorText(value));}
    finally{setBusy(false);}
  };

  const jobId=job?.id,jobState=job?.state;
  useEffect(()=>{
    if(!jobId||!jobState||!ACTIVE_STATES.has(jobState))return;
    let disposed=false;
    const refresh=async()=>{try{const next=await new LocalTrainingClient(endpoint).job(jobId);if(!disposed)setJob(next);}catch(value){if(!disposed)setError(errorText(value));}};
    const timer=window.setInterval(()=>void refresh(),1500);return()=>{disposed=true;window.clearInterval(timer);};
  },[endpoint,jobId,jobState]);

  const start=async()=>{
    setBusy(true);setError(undefined);
    try{
      const ids=device==='gpu'?gpuIds.split(/[\s,]+/).filter(Boolean).map(Number):[];
      if(ids.some(id=>!Number.isInteger(id)||id<0))throw new Error('GPU 编号必须是非负整数');
      const next=await new LocalTrainingClient(endpoint).start({taskId,numEnvs,maxIterations,seed,runName,device,gpuIds:ids,wandbMode});
      setJob(next);try{localStorage.setItem(JOB_KEY,next.id);}catch{/* ignore */}
    }catch(value){setError(errorText(value));}finally{setBusy(false);}
  };
  const cancel=async()=>{if(!job)return;setBusy(true);setError(undefined);try{setJob(await new LocalTrainingClient(endpoint).cancel(job.id));}catch(value){setError(errorText(value));}finally{setBusy(false);}};
  const importResult=async()=>{if(!job)return;setBusy(true);setError(undefined);try{onPolicyReady(await new LocalTrainingClient(endpoint).downloadPolicy(job.id));}catch(value){setError(errorText(value));}finally{setBusy(false);}};
  const active=Boolean(job&&ACTIVE_STATES.has(job.state));

  return <div>
    <label className="block text-xs text-text-secondary"><span className="mb-1 block">本地训练服务</span><div className="flex gap-2"><input aria-label="本地训练服务地址" className="field h-7 min-w-0 flex-1 px-2 text-xs text-text-primary" value={endpoint} disabled={active} onChange={event=>setEndpoint(event.target.value)}/><Button icon={<Link className="h-3.5 w-3.5"/>} disabled={busy||active} onClick={()=>void connect()}>连接</Button></div></label>
    <div className="mt-2 flex items-center justify-between rounded-md border border-border bg-surface px-2 py-1.5 text-[10px] text-text-tertiary"><span className="flex min-w-0 items-center gap-1.5 truncate"><Server className="h-3.5 w-3.5"/>{server?.trainerRoot??'请先启动本地训练服务'}</span><Badge tone={server?.ready?'success':'warning'}>{server?.ready?'可用':'离线'}</Badge></div>
    {server?.ready&&!job&&<div className="mt-3 space-y-2">
      <Field label="训练任务"><Select aria-label="训练任务" className="w-full" value={taskId} onChange={event=>setTaskId(event.target.value)}>{server.tasks.map(task=><option key={task} value={task}>{task}</option>)}</Select></Field>
      <div className="grid grid-cols-2 gap-2"><NumberField label="并行环境" value={numEnvs} min={1} max={16384} onChange={setNumEnvs}/><NumberField label="训练迭代" value={maxIterations} min={1} max={1000000} onChange={setMaxIterations}/><NumberField label="随机种子" value={seed} min={0} max={2147483647} onChange={setSeed}/><Field label="运行名称"><input aria-label="运行名称" className="field h-7 w-full px-2 text-xs text-text-primary" value={runName} onChange={event=>setRunName(event.target.value)}/></Field></div>
      <div className="grid grid-cols-2 gap-2"><Field label="计算设备"><Select aria-label="计算设备" className="w-full" value={device} onChange={event=>setDevice(event.target.value as TrainingDevice)}><option value="gpu">GPU</option><option value="cpu">CPU</option></Select></Field><Field label="GPU 编号"><input aria-label="GPU 编号" className="field h-7 w-full px-2 text-xs text-text-primary disabled:opacity-40" value={gpuIds} disabled={device==='cpu'} onChange={event=>setGpuIds(event.target.value)}/></Field></div>
      <Field label="实验记录"><Select aria-label="W&B 模式" className="w-full" value={wandbMode} onChange={event=>setWandbMode(event.target.value as WandbMode)}><option value="offline">本地离线（默认，无需登录）</option><option value="disabled">完全禁用 W&amp;B</option><option value="online">在线 W&amp;B（需要 API Key）</option></Select></Field>
      <Button variant="primary" className="w-full" icon={<Play className="h-3.5 w-3.5"/>} disabled={busy} onClick={()=>void start()}>发起本地训练</Button>
      <p className="text-[10px] leading-4 text-text-tertiary">训练使用本地 mjlab 任务资产，不会把浏览器中的模型上传到网络。服务一次只运行一个训练任务。</p>
    </div>}
    {job&&<div className="mt-3 rounded-lg border border-border bg-surface p-2.5">
      <div className="mb-2 flex items-center justify-between gap-2"><span className="truncate text-xs font-medium text-text-primary" title={job.id}>{job.taskId}</span><Badge tone={job.state==='succeeded'?'success':job.state==='failed'||job.state==='cancelled'?'warning':'accent'}>{stateLabel(job.state)}</Badge></div>
      <ProgressBar value={job.progress} label="训练进度"/><div className="mt-2"><PropertyRow label="迭代" value={`${job.iteration} / ${job.maxIterations}`}/><PropertyRow label="状态" value={job.message}/></div>
      {job.logs.length>0&&<details className="mt-2"><summary className="cursor-pointer text-[10px] text-text-secondary">最近日志</summary><pre className="mt-1 max-h-36 overflow-auto whitespace-pre-wrap break-all rounded bg-app p-2 text-[9px] leading-4 text-text-tertiary">{job.logs.slice(-40).join('\n')}</pre></details>}
      <div className="mt-3 grid grid-cols-2 gap-2">{active?<Button variant="danger" className="col-span-2" icon={<Square className="h-3.5 w-3.5"/>} disabled={busy} onClick={()=>void cancel()}>停止训练</Button>:<><Button disabled={busy||!job.artifactReady} icon={<Download className="h-3.5 w-3.5"/>} onClick={()=>void importResult()}>导入策略</Button><Button onClick={()=>{setJob(undefined);try{localStorage.removeItem(JOB_KEY);}catch{/* ignore */}}}>新建任务</Button></>}</div>
    </div>}
    {error&&<p role="alert" className="mt-2 break-words rounded bg-danger/10 p-2 text-[10px] leading-4 text-danger">{error}</p>}
  </div>;
}

function Field({label,children}:{label:string;children:ReactNode}){return <label className="block text-[10px] text-text-tertiary"><span className="mb-1 block">{label}</span>{children}</label>;}
function NumberField({label,value,min,max,onChange}:{label:string;value:number;min:number;max:number;onChange(value:number):void}){return <Field label={label}><input aria-label={label} type="number" className="field h-7 w-full px-2 text-xs text-text-primary" value={value} min={min} max={max} onChange={event=>onChange(Number(event.target.value))}/></Field>;}