const fields = ['student_no', 'name', 'topic'] as const;
type IdentityField = typeof fields[number];
const labels = { student_no: '学号', name: '姓名', topic: '选题' };
const categories: Record<string, string> = { stage1: '阶段报告1', stage2: '阶段报告2', stage3: '阶段报告3',
  final_report: '最终报告', presentation: '汇报PPT/PDF' };
const text = (value: unknown) => String(value ?? '').trim();
const fileName = (file: any) => text(file.relative_path).split('/').pop() || '文件';

export function reviewImport(project: any) {
  const selected = (project.files || []).filter((file: any) => file.status !== 'ignored');
  const metadata = (project.files || []).some((file: any) => file.detected_identity != null);
  const identity: Record<IdentityField, string> = { student_no: '', name: '', topic: '' };
  const warnings: string[] = [];
  for (const field of fields) {
    const sources = new Map<string, string[]>();
    for (const file of selected) {
      const value = text(file.detected_identity?.[field]);
      if (value) sources.set(value, [...(sources.get(value) || []), fileName(file)]);
    }
    const folderValue = text(project.folder_identity?.[field]);
    const values = [...sources.keys()];
    identity[field] = folderValue || (values.length === 1 ? values[0] : '');
    if (values.length > 1) {
      warnings.push(`${labels[field]}冲突：${values.map(value => `${value}（${sources.get(value)!.join('、')}）`).join('；')}`);
    } else if (folderValue && values.length === 1 && folderValue !== values[0]) {
      warnings.push(`${labels[field]}与目录不一致：封面为${values[0]}（${sources.get(values[0])!.join('、')}），目录为${folderValue}`);
    }
  }
  if (!metadata) warnings.push(...(project.warnings || []));

  const errors: string[] = [];
  if (!/^[0-9]{5,20}$/.test(text(project.student_no))) errors.push('学号必须为5–20位数字');
  if (!text(project.name)) errors.push('请填写姓名');
  if (!text(project.topic)) errors.push('请填写选题');
  if (!selected.length) errors.push('至少选择1份资料');
  const counts = new Map<string, number>();
  for (const file of selected) {
    if (!categories[file.category]) errors.push(`${fileName(file)}：请选择材料类型`);
    else counts.set(file.category, (counts.get(file.category) || 0) + 1);
    if (file.error) errors.push(`${fileName(file)}：无法读取，请修复文件或设为忽略`);
  }
  for (const [category, count] of counts) {
    if (count > 1) errors.push(`${categories[category]}选了${count}份，请只保留1份，其余设为忽略`);
  }
  const missing = Object.keys(categories).filter(category => !selected.some((file: any) => file.category === category));
  return { selected, metadata, identity, warnings, errors, missing };
}

export function fillImportIdentity(project: any, force = false) {
  const review = reviewImport(project);
  if (!review.metadata) return project;
  for (const field of fields) {
    if (force || !project.identity_edits?.[field]) project[field] = review.identity[field];
  }
  if (force) project.identity_edits = {};
  return project;
}

export function importErrors(projects: any[] | undefined, versionId: number | undefined) {
  const errors = versionId ? [] : ['请选择已发布课程版本'];
  if (!projects?.length) return [...errors, '当前目录没有PDF、DOCX或PPTX资料，请重新扫描资料目录'];
  for (const project of projects) {
    errors.push(...reviewImport(project).errors.map(error => `${project.relative_dir}：${error}`));
  }
  return errors;
}