import React, { useEffect, useRef, useState } from 'react';
import { useTheme } from '../../contexts';
import { Content } from '../../components/layout/Content';
import { TPattern } from '../../components/common/TPattern';
import { getDocumentList, getDocumentStatus, searchRegulations, uploadDocument, deleteDocument, retryDocument, type RegulationSearchItem } from '../../api/docs';
import type { Doc } from '../../types';

type PipelineStatus = 'idle' | 'running' | 'completed' | 'error';

const PIPELINE_STEPS = [
  { name: 'LOAD' },
  { name: 'PARSE' },
  { name: 'CHUNK' },
  { name: 'EMBED' },
  { name: 'STORE' },
];

const REGULATION_TYPES = ['', '国家标准', '行业标准', '地方标准', '企业标准', '法律法规', '监管规定'];

const STEP_DURATION_MS = 700;
const INITIAL_SEARCH_QUERY = '新能源汽车电池安全要求';

function wait(ms: number) {
  return new Promise<void>((resolve) => { window.setTimeout(resolve, ms); });
}

export const DocsPage: React.FC = () => {
  const { theme, isDark } = useTheme();
  const fileInputRef = useRef<HTMLInputElement>(null);
  const pipelineRunIdRef = useRef(0);

  const [activeStep, setActiveStep] = useState<number>(-1);
  const [completedSteps, setCompletedSteps] = useState<number[]>([]);
  const [pipelineStatus, setPipelineStatus] = useState<PipelineStatus>('idle');
  const [docs, setDocs] = useState<Doc[]>([]);
  const [uploading, setUploading] = useState(false);
  const [uploadFileName, setUploadFileName] = useState('');
  const [loading, setLoading] = useState(true);
  const [searchQuery, setSearchQuery] = useState(INITIAL_SEARCH_QUERY);
  const [searchResults, setSearchResults] = useState<RegulationSearchItem[]>([]);
  const [searchLoading, setSearchLoading] = useState(false);
  const [searchError, setSearchError] = useState('');

  // Upload metadata
  const [regulationType, setRegulationType] = useState('');
  const [version, setVersion] = useState('');

  // Batch queue: files waiting to be uploaded after the current one finishes
  const batchQueueRef = useRef<File[]>([]);

  async function loadDocuments() {
    setLoading(true);
    try {
      const response = await getDocumentList();
      const apiDocs: Doc[] = response.docs.map((doc) => ({
        id: parseInt(String(doc.id).replace('doc-', ''), 10) || Math.floor(Math.random() * 10000),
        name: doc.name,
        chunks: doc.chunks,
        size: doc.updated_at ? new Date(doc.updated_at).toLocaleString() : 'Indexed document',
        status: doc.status === 'indexed' ? 'indexed' : doc.status === 'failed' ? 'failed' : 'parsing',
        docId: doc.id,
        downloadUrl: doc.download_url,
        updatedAt: doc.updated_at,
        summary: doc.summary,
        regulationType: doc.regulation_type,
        version: doc.version,
      }));
      setDocs(apiDocs);
    } catch (error) {
      console.error('Failed to load documents:', error);
      setDocs([]);
    } finally {
      setLoading(false);
    }
  }

  async function runSearch(query: string) {
    if (!query.trim()) return;
    setSearchLoading(true);
    setSearchError('');
    try {
      const response = await searchRegulations(query.trim(), 8);
      setSearchResults(response.results);
    } catch (error) {
      console.error('Failed to search regulations:', error);
      setSearchError(error instanceof Error ? error.message : '检索失败');
      setSearchResults([]);
    } finally {
      setSearchLoading(false);
    }
  }

  useEffect(() => {
    const timerId = window.setTimeout(() => { void loadDocuments(); }, 0);
    return () => window.clearTimeout(timerId);
  }, []);

  useEffect(() => {
    const timerId = window.setTimeout(() => { void runSearch(INITIAL_SEARCH_QUERY); }, 0);
    return () => window.clearTimeout(timerId);
  }, []);

  useEffect(() => {
    return () => { pipelineRunIdRef.current += 1; };
  }, []);

  useEffect(() => {
    const parsingDocs = docs.filter(
      (doc) => doc.status === 'parsing' && doc.docId && !doc.docId.startsWith('pending-')
    );
    if (parsingDocs.length === 0) return;

    const timerId = window.setInterval(() => {
      parsingDocs.forEach((doc) => {
        void getDocumentStatus(doc.docId!).then((res) => {
          if (res.status === 'indexed' || res.status === 'failed') {
            setDocs((prev) =>
              prev.map((d) =>
                d.docId === doc.docId
                  ? {
                      ...d,
                      status: res.status === 'indexed' ? 'indexed' : 'failed',
                      chunks: res.num_chunks ?? d.chunks,
                      summary: res.summary ?? d.summary,
                      regulationType: res.regulation_type ?? d.regulationType,
                      version: res.version ?? d.version,
                    }
                  : d
              )
            );
          }
        }).catch(() => {});
      });
    }, 5000);

    return () => window.clearInterval(timerId);
  }, [docs]);

  const runPipelineFlow = async (runId: number, uploadPromise: Promise<Awaited<ReturnType<typeof uploadDocument>>>) => {
    const guard = (fn: () => void) => { if (pipelineRunIdRef.current !== runId) return false; fn(); return true; };

    for (let i = 0; i < PIPELINE_STEPS.length - 1; i++) {
      if (!guard(() => setActiveStep(i))) return;
      await wait(STEP_DURATION_MS);
      if (!guard(() => setCompletedSteps((p) => p.includes(i) ? p : [...p, i]))) return;
    }

    if (!guard(() => setActiveStep(PIPELINE_STEPS.length - 1))) return;
    await uploadPromise;
    if (!guard(() => setCompletedSteps((p) => { const last = PIPELINE_STEPS.length - 1; return p.includes(last) ? p : [...p, last]; }))) return;

    await wait(240);
    if (pipelineRunIdRef.current !== runId) return;
    setActiveStep(-1);
    setPipelineStatus('completed');
  };

  const uploadSingleFile = async (file: File, runId: number) => {
    setUploading(true);
    setUploadFileName(file.name);
    setActiveStep(-1);
    setCompletedSteps([]);
    setPipelineStatus('running');

    const fileSizeMB = (file.size / (1024 * 1024)).toFixed(1);
    const tempDocId = `pending-${Date.now()}`;
    const newDoc: Doc = {
      id: Date.now(),
      name: file.name,
      chunks: 0,
      size: `${fileSizeMB}MB`,
      status: 'parsing',
      docId: tempDocId,
      regulationType: regulationType || undefined,
      version: version || undefined,
    };

    setDocs((prev) => [newDoc, ...prev]);

    const uploadPromise = uploadDocument(file, {
      regulationType: regulationType || undefined,
      version: version || undefined,
    });
    void runPipelineFlow(runId, uploadPromise);

    try {
      const uploadRes = await uploadPromise;
      if (pipelineRunIdRef.current !== runId) return;

      setDocs((prev) =>
        prev.map((doc) =>
          doc.id === newDoc.id
            ? { ...doc, status: 'indexed', docId: uploadRes.doc_id, chunks: uploadRes.num_chunks || doc.chunks, summary: uploadRes.summary }
            : doc
        )
      );
      void loadDocuments();
    } catch (error) {
      console.error('Upload failed:', error);
      if (pipelineRunIdRef.current !== runId) return;
      setDocs((prev) => prev.filter((doc) => doc.id !== newDoc.id));
      setPipelineStatus('error');
      setActiveStep(-1);
      setCompletedSteps([]);
    } finally {
      setUploading(false);
      setUploadFileName('');
      if (fileInputRef.current) fileInputRef.current.value = '';

      // Process next file in batch queue
      const next = batchQueueRef.current.shift();
      if (next) {
        const nextRunId = pipelineRunIdRef.current + 1;
        pipelineRunIdRef.current = nextRunId;
        void uploadSingleFile(next, nextRunId);
      }
    }
  };

  const handleFileSelect = async (event: React.ChangeEvent<HTMLInputElement>) => {
    const files = Array.from(event.target.files ?? []);
    if (files.length === 0 || uploading) return;

    const [first, ...rest] = files;
    batchQueueRef.current = rest;

    const runId = pipelineRunIdRef.current + 1;
    pipelineRunIdRef.current = runId;
    await uploadSingleFile(first, runId);
  };

  const handleDelete = async (docId: string) => {
    try {
      await deleteDocument(docId);
      setDocs((prev) => prev.filter((doc) => doc.docId !== docId));
    } catch (error) {
      console.error('Delete failed:', error);
    }
  };

  const handleRetry = async (docId: string) => {
    setDocs((prev) => prev.map((doc) => doc.docId === docId ? { ...doc, status: 'parsing' } : doc));
    try {
      const result = await retryDocument(docId);
      setDocs((prev) =>
        prev.map((doc) => doc.docId === docId ? { ...doc, status: 'indexed', chunks: result.num_chunks || doc.chunks } : doc)
      );
    } catch (error) {
      console.error('Retry failed:', error);
      setDocs((prev) => prev.map((doc) => doc.docId === docId ? { ...doc, status: 'failed' } : doc));
    }
  };

  const triggerFileUpload = () => { if (uploading) return; fileInputRef.current?.click(); };

  const handleDragOver = (event: React.DragEvent) => { event.preventDefault(); event.stopPropagation(); };

  const handleDrop = (event: React.DragEvent) => {
    event.preventDefault();
    event.stopPropagation();
    const files = Array.from(event.dataTransfer.files);
    if (files.length === 0 || uploading) return;

    const [first, ...rest] = files;
    batchQueueRef.current = rest;
    const runId = pipelineRunIdRef.current + 1;
    pipelineRunIdRef.current = runId;
    void uploadSingleFile(first, runId);
  };

  const getStepStyle = (index: number) => {
    if (activeStep === index) return { background: theme.bgCard, border: `2px solid ${theme.accent}`, boxShadow: `0 0 12px ${theme.accent}40` };
    if (completedSteps.includes(index)) return { background: theme.bgCard, border: `1px solid ${theme.green}` };
    return { background: theme.bgCard, border: `1px solid ${theme.border}` };
  };

  const getCheckStyle = (index: number) => {
    if (activeStep === index) return { background: theme.gradientAccent, color: '#fff', animation: 'pulse 0.6s infinite' };
    if (completedSteps.includes(index)) return { background: theme.green, color: '#fff' };
    return { background: theme.bgHover, color: theme.text3 };
  };

  const getPipelineHint = () => {
    if (pipelineStatus === 'running') {
      const queueLen = batchQueueRef.current.length;
      const suffix = queueLen > 0 ? ` (+${queueLen} 待上传)` : '';
      return `${activeStep >= 0 ? PIPELINE_STEPS[activeStep].name : 'LOAD'} · ${uploadFileName}${suffix}`;
    }
    if (pipelineStatus === 'completed') return 'PIPELINE COMPLETE';
    if (pipelineStatus === 'error') return 'PIPELINE FAILED';
    return 'WAITING FOR UPLOAD';
  };

  const inputStyle: React.CSSProperties = {
    padding: '8px 12px',
    fontSize: 13,
    background: theme.bgCard,
    border: `1px solid ${theme.border}`,
    borderRadius: 8,
    color: theme.text,
    outline: 'none',
  };

  return (
    <Content>
      <TPattern />

      <section style={{ marginBottom: 56 }}>
        <h2 style={{ fontSize: 14, fontWeight: 600, color: theme.accent, marginBottom: 20, letterSpacing: '1px' }}>
          UPLOAD
        </h2>

        <input
          ref={fileInputRef}
          type="file"
          accept=".pdf,.docx,.doc"
          multiple
          onChange={handleFileSelect}
          style={{ display: 'none' }}
        />

        {/* Metadata row */}
        <div style={{ display: 'flex', gap: 12, marginBottom: 12 }}>
          <select
            value={regulationType}
            onChange={(e) => setRegulationType(e.target.value)}
            style={{ ...inputStyle, flex: 1 }}
          >
            {REGULATION_TYPES.map((t) => (
              <option key={t} value={t}>{t || '法规类型（可选）'}</option>
            ))}
          </select>
          <input
            value={version}
            onChange={(e) => setVersion(e.target.value)}
            placeholder="版本号（可选，如 2024）"
            style={{ ...inputStyle, flex: 1 }}
          />
        </div>

        <div
          onClick={triggerFileUpload}
          onDragOver={handleDragOver}
          onDrop={handleDrop}
          style={{
            border: `2px solid ${uploading ? theme.accent : theme.border}`,
            borderRadius: 16,
            padding: 64,
            textAlign: 'center',
            background: theme.bgCard,
            transition: 'all 0.3s ease',
            cursor: uploading ? 'wait' : 'pointer',
            boxShadow: !isDark ? '0 4px 16px rgba(226,0,116,0.08)' : 'none',
            opacity: uploading ? 0.78 : 1,
          }}
        >
          <div style={{ width: 80, height: 80, borderRadius: 20, background: theme.bgHover, display: 'flex', alignItems: 'center', justifyContent: 'center', margin: '0 auto 20px' }}>
            {uploading ? (
              <div style={{ animation: 'spin 1s linear infinite' }}>
                <svg width="36" height="36" viewBox="0 0 24 24" fill="none">
                  <circle cx="12" cy="12" r="10" stroke={theme.accent} strokeWidth="2" strokeDasharray="60" strokeDashoffset="20" />
                </svg>
              </div>
            ) : (
              <svg width="36" height="36" viewBox="0 0 24 24" fill="none">
                <path d="M12 4L12 16M12 4L7 9M12 4L17 9" stroke={theme.accent} strokeWidth="2" strokeLinecap="round" />
                <path d="M4 18H20" stroke={theme.accent} strokeWidth="2" strokeLinecap="round" />
              </svg>
            )}
          </div>
          <div style={{ fontSize: 16, fontWeight: 500, marginBottom: 8 }}>
            {uploading ? '正在上传并启动处理链路...' : '拖拽文件或点击上传（支持多选）'}
          </div>
          <div className="mono" style={{ fontSize: 12, color: theme.text3 }}>
            {uploading ? uploadFileName : 'PDF · DOCX · DOC · MAX 100MB · 支持批量'}
          </div>
        </div>
      </section>

      <section style={{ marginBottom: 40 }}>
        <h2 style={{ fontSize: 14, fontWeight: 600, color: theme.accent, marginBottom: 20, letterSpacing: '1px' }}>
          PROCESSING PIPELINE
        </h2>

        <div
          className="mono"
          style={{
            fontSize: 11,
            color: pipelineStatus === 'error' ? '#d64545' : pipelineStatus === 'completed' ? theme.green : theme.text3,
            letterSpacing: '1px',
            marginBottom: 12,
          }}
        >
          {getPipelineHint()}
        </div>

        <div style={{ display: 'flex', gap: 16 }}>
          {PIPELINE_STEPS.map((step, index) => {
            const isCompleted = completedSteps.includes(index);
            const isActive = activeStep === index;
            const arrowActive = activeStep > index || isCompleted;

            return (
              <div
                key={step.name}
                style={{ flex: 1, padding: 20, textAlign: 'center', borderRadius: 12, position: 'relative', boxShadow: !isDark ? '0 2px 8px rgba(226,0,116,0.04)' : 'none', transition: 'all 0.3s ease', ...getStepStyle(index) }}
              >
                <div style={{ width: 36, height: 36, borderRadius: 8, display: 'flex', alignItems: 'center', justifyContent: 'center', margin: '0 auto 12px', fontSize: 16, transition: 'all 0.3s ease', ...getCheckStyle(index) }}>
                  {isActive ? step.name : isCompleted ? '✓' : step.name}
                </div>
                <div className="mono" style={{ fontSize: 12, fontWeight: 600 }}>{step.name}</div>
                <div className="mono" style={{ fontSize: 10, color: theme.text3, marginTop: 8 }}>
                  {isCompleted ? 'DONE' : isActive ? 'RUNNING' : 'PENDING'}
                </div>
                {index < PIPELINE_STEPS.length - 1 && (
                  <div style={{ position: 'absolute', right: -8, top: '50%', transform: 'translateY(-50%)', color: arrowActive ? theme.green : theme.borderLight, fontWeight: arrowActive ? 700 : 400, opacity: arrowActive ? 1 : 0.45, transition: 'all 0.3s ease' }}>
                    →
                  </div>
                )}
              </div>
            );
          })}
        </div>
      </section>

      <section style={{ display: 'grid', gridTemplateColumns: '1fr 1fr', gap: 24, marginBottom: 56 }}>
        <div>
          <h2 style={{ fontSize: 14, fontWeight: 600, color: theme.accent, marginBottom: 20, letterSpacing: '1px' }}>
            文档管理清单 ({loading ? '...' : docs.length})
          </h2>

          <div style={{ display: 'flex', flexDirection: 'column', gap: 12 }}>
            {docs.map((doc) => (
              <div
                key={doc.id}
                style={{ display: 'flex', alignItems: 'center', justifyContent: 'space-between', padding: 20, background: theme.bgCard, borderRadius: 12, border: `1px solid ${doc.status === 'parsing' ? theme.accent : theme.border}`, transition: 'all 0.2s ease', boxShadow: !isDark ? '0 2px 8px rgba(226,0,116,0.04)' : 'none' }}
              >
                <div style={{ display: 'flex', alignItems: 'flex-start', gap: 16 }}>
                  <div style={{ width: 44, height: 44, borderRadius: 10, background: theme.bgHover, display: 'flex', alignItems: 'center', justifyContent: 'center', flexShrink: 0 }}>
                    <svg width="20" height="20" viewBox="0 0 24 24" fill="none">
                      <path d="M14 2H6C5 2 4 3 4 4V20C4 21 5 22 6 22H18C19 22 20 21 20 20V8L14 2Z" stroke={theme.accent} strokeWidth="1.5" />
                      <path d="M14 2V8H20" stroke={theme.accent} strokeWidth="1.5" />
                    </svg>
                  </div>

                  <div>
                    <div style={{ fontSize: 15, fontWeight: 500 }}>{doc.name}</div>
                    <div className="mono" style={{ fontSize: 11, color: theme.text3 }}>
                      {doc.updatedAt ? new Date(doc.updatedAt).toLocaleString() : doc.size}
                      {doc.docId ? ` · ${doc.docId}` : ''}
                    </div>
                    {/* Tags row */}
                    {(doc.regulationType || doc.version) && (
                      <div style={{ display: 'flex', gap: 6, marginTop: 5, flexWrap: 'wrap' }}>
                        {doc.regulationType && (
                          <span style={{ fontSize: 11, padding: '2px 8px', borderRadius: 4, background: `${theme.accent}18`, color: theme.accent, fontWeight: 500 }}>
                            {doc.regulationType}
                          </span>
                        )}
                        {doc.version && (
                          <span style={{ fontSize: 11, padding: '2px 8px', borderRadius: 4, background: theme.bgHover, color: theme.text2 }}>
                            v{doc.version}
                          </span>
                        )}
                      </div>
                    )}
                    {doc.summary && (
                      <div style={{ fontSize: 12, color: theme.text2, marginTop: 6, lineHeight: 1.5, maxWidth: 320, display: '-webkit-box', WebkitLineClamp: 2, WebkitBoxOrient: 'vertical', overflow: 'hidden' }}>
                        {doc.summary}
                      </div>
                    )}
                  </div>
                </div>

                <div style={{ display: 'flex', alignItems: 'flex-start', gap: 12, flexShrink: 0 }}>
                  {doc.status === 'failed' && doc.docId && !doc.docId.startsWith('pending-') && (
                    <button onClick={() => void handleRetry(doc.docId!)} style={{ fontSize: 12, padding: '6px 12px', background: 'transparent', border: `1px solid ${theme.accent}`, borderRadius: 6, color: theme.accent, cursor: 'pointer' }}>
                      重试
                    </button>
                  )}
                  {doc.downloadUrl && doc.status === 'indexed' && (
                    <a href={doc.downloadUrl} target="_blank" rel="noreferrer" style={{ fontSize: 12, color: theme.accent, textDecoration: 'none' }}>
                      下载
                    </a>
                  )}
                  <div className="mono" style={{ fontSize: 12, padding: '6px 12px', background: theme.bgHover, borderRadius: 6, color: doc.status === 'failed' ? '#d64545' : theme.text2 }}>
                    {doc.status === 'parsing' ? '处理中...' : doc.status === 'failed' ? '处理失败' : `${doc.chunks} chunks`}
                  </div>
                  {doc.docId && !doc.docId.startsWith('pending-') && (
                    <button onClick={() => void handleDelete(doc.docId!)} style={{ fontSize: 12, padding: '6px 10px', background: 'transparent', border: `1px solid ${theme.border}`, borderRadius: 6, color: theme.text3, cursor: 'pointer' }}>
                      删除
                    </button>
                  )}
                </div>
              </div>
            ))}
          </div>
        </div>

        <div>
          <h2 style={{ fontSize: 14, fontWeight: 600, color: theme.accent, marginBottom: 20, letterSpacing: '1px' }}>
            文档管理内法规检索
          </h2>

          <div style={{ display: 'flex', gap: 10, marginBottom: 16 }}>
            <input
              value={searchQuery}
              onChange={(event) => setSearchQuery(event.target.value)}
              onKeyDown={(event) => { if (event.key === 'Enter') void runSearch(searchQuery); }}
              placeholder="输入法规关键词、条款或制度主题"
              style={{ flex: 1, padding: 12, fontSize: 14, background: theme.bgCard, border: `1px solid ${theme.border}`, borderRadius: 8, color: theme.text, outline: 'none' }}
            />
            <button
              onClick={() => void runSearch(searchQuery)}
              disabled={searchLoading || !searchQuery.trim()}
              style={{ padding: '12px 18px', fontSize: 13, fontWeight: 600, background: searchLoading || !searchQuery.trim() ? theme.bgHover : theme.gradientAccent, color: searchLoading || !searchQuery.trim() ? theme.text3 : '#fff', border: 'none', borderRadius: 8, cursor: searchLoading || !searchQuery.trim() ? 'not-allowed' : 'pointer' }}
            >
              检索
            </button>
          </div>

          {searchError && <div style={{ marginBottom: 12, fontSize: 13, color: '#d64545' }}>{searchError}</div>}

          <div style={{ display: 'flex', flexDirection: 'column', gap: 12 }}>
            {searchResults.map((item) => (
              <div key={`${item.id}-${item.file}`} style={{ padding: 18, background: theme.bgCard, borderRadius: 12, border: `1px solid ${theme.border}`, boxShadow: !isDark ? '0 2px 8px rgba(226,0,116,0.04)' : 'none' }}>
                <div style={{ display: 'flex', justifyContent: 'space-between', gap: 12, marginBottom: 6 }}>
                  <div style={{ fontSize: 14, fontWeight: 600, color: theme.text }}>{item.file}</div>
                  <div className="mono" style={{ fontSize: 11, color: theme.accent }}>{(item.score * 100).toFixed(1)}%</div>
                </div>
                <div className="mono" style={{ fontSize: 11, color: theme.text3, marginBottom: 8 }}>
                  {item.clause}{item.tags.length > 0 ? ` · ${item.tags.join(' · ')}` : ''}
                </div>
                <div style={{ fontSize: 12, color: theme.text2, lineHeight: 1.6 }}>{item.content}</div>
              </div>
            ))}

            {!searchLoading && searchResults.length === 0 && (
              <div style={{ padding: 24, borderRadius: 12, background: theme.bgCard, border: `1px solid ${theme.border}`, textAlign: 'center', color: theme.text3 }}>
                暂无检索结果
              </div>
            )}
          </div>
        </div>
      </section>
    </Content>
  );
};
