/**
 * 数据校验与冲突提示（1.7.11）。
 *
 * 两层：
 * - RowValidator：按列规则（必填/长度/正则）校验单元格与整行；
 * - ConflictDetector：乐观并发——提交前比对「读取时版本」与「当前库中版本」，
 *   不一致即判定冲突，UI 提示用户重新加载或覆盖。
 */
export interface ColumnRule {
  column: string;
  required: boolean;
  minLength: number;
  maxLength: number;
  /** 正则；为空表示不校验。 */
  pattern: string;
}

export interface ValidationIssue {
  column: string;
  message: string;
}

export class RowValidator {
  /** 校验单元格，返回错误消息（空数组通过）。 */
  static validateCell(rule: ColumnRule, value: string): string[] {
    const errors: string[] = [];
    const text: string = value === undefined || value === null ? '' : value;
    if (rule.required && text.trim().length === 0) {
      errors.push(rule.column + ' is required');
      return errors;
    }
    if (text.length > 0 && rule.maxLength > 0 && text.length > rule.maxLength) {
      errors.push(rule.column + ' exceeds max length ' + rule.maxLength);
    }
    if (text.length > 0 && rule.minLength > 0 && text.length < rule.minLength) {
      errors.push(rule.column + ' is shorter than min length ' + rule.minLength);
    }
    if (text.length > 0 && rule.pattern.length > 0 && !new RegExp(rule.pattern).test(text)) {
      errors.push(rule.column + ' does not match pattern ' + rule.pattern);
    }
    return errors;
  }

  /** 校验整行（values: 列 → 值）。 */
  static validateRow(values: Map<string, string>, rules: ColumnRule[]): ValidationIssue[] {
    const issues: ValidationIssue[] = [];
    for (let i = 0; i < rules.length; i++) {
      const rule: ColumnRule = rules[i];
      const value: string | undefined = values.get(rule.column);
      const errors: string[] = RowValidator.validateCell(rule, value === undefined ? '' : value);
      for (let j = 0; j < errors.length; j++) {
        issues.push({ column: rule.column, message: errors[j] });
      }
    }
    return issues;
  }

  /** 便捷：无错误为 true。 */
  static isValid(values: Map<string, string>, rules: ColumnRule[]): boolean {
    return RowValidator.validateRow(values, rules).length === 0;
  }
}

export interface ConflictInfo {
  conflict: boolean;
  reason: string;
}

export class ConflictDetector {
  /**
   * 乐观并发检测：读取时版本与提交时版本不同即冲突。
   * 版本可以是时间戳、行版本号或 updated_at 字符串。
   */
  static detect(fetchedVersion: string, currentVersion: string): ConflictInfo {
    if (fetchedVersion === currentVersion) {
      return { conflict: false, reason: '' };
    }
    return {
      conflict: true,
      reason: 'row changed since load: fetched=' + fetchedVersion + ', current=' + currentVersion
    };
  }

  /** 批量检测（行号 → {fetched, current}）。 */
  static detectBatch(pairs: Map<number, string[]>): Map<number, ConflictInfo> {
    const out: Map<number, ConflictInfo> = new Map<number, ConflictInfo>();
    pairs.forEach((versions: string[], row: number) => {
      if (versions.length >= 2) {
        out.set(row, ConflictDetector.detect(versions[0], versions[1]));
      }
    });
    return out;
  }
}