import { readFileSync, writeFileSync, existsSync } from 'fs';
import { parse } from 'csv-parse/browser/esm/sync';
import { stringify } from 'csv-stringify/browser/esm/sync';
import yaml from 'js-yaml';
import type { DeckFrontmatter } from '../frontmatter/read-frontmatter.js';

/**
 * 卡牌数据
 */
export interface CardData {
  label?: string;
  [key: string]: string | undefined;
}

/**
 * 卡牌 CRUD 参数
 */
export interface CardCrudParams {
  /**
   * CSV 文件路径
   */
  csv_file: string;
  /**
   * 操作类型
   */
  action: 'create' | 'read' | 'update' | 'delete';
  /**
   * 卡牌数据（单张或数组）
   */
  cards?: CardData | CardData[];
  /**
   * 要读取/更新的卡牌 label（用于 read/update/delete）
   */
  label?: string | string[];
}

/**
 * 卡牌 CRUD 结果
 */
export interface CardCrudResult {
  success: boolean;
  message: string;
  cards?: CardData[];
  count?: number;
}

/**
 * 解析 CSV 文件的 frontmatter
 */
function parseFrontMatter(content: string): { frontmatter?: DeckFrontmatter; csvContent: string } {
  const parts = content.trim().split(/(?:^|\n)---\s*\n/g);

  if (parts.length !== 3 || parts[0] !== '') {
    return { csvContent: content };
  }

  try {
    const frontmatterStr = parts[1].trim();
    const frontmatter = yaml.load(frontmatterStr) as DeckFrontmatter | undefined;
    const csvContent = parts.slice(2).join('---\n').trimStart();
    return { frontmatter, csvContent };
  } catch (error) {
    console.warn('Failed to parse front matter:', error);
    return { csvContent: content };
  }
}

/**
 * 序列化 frontmatter 为 YAML 字符串
 */
function serializeFrontMatter(frontmatter: DeckFrontmatter): string {
  const yamlStr = yaml.dump(frontmatter, {
    indent: 2,
    lineWidth: -1,
    noRefs: true,
    quotingType: '"',
    forceQuotes: false
  });
  return `---\n${yamlStr}---\n`;
}

/**
 * 加载 CSV 数据（包含 frontmatter）
 */
function loadCSVWithFrontmatter(filePath: string): {
  frontmatter?: DeckFrontmatter;
  records: CardData[];
  headers: string[];
} {
  const content = readFileSync(filePath, 'utf-8');
  const { frontmatter, csvContent } = parseFrontMatter(content);

  const records = parse(csvContent, {
    columns: true,
    comment: '#',
    trim: true,
    skipEmptyLines: true
  }) as CardData[];

  // 获取表头
  const firstLine = csvContent.split('\n')[0];
  const headers = firstLine.split(',').map(h => h.trim());

  return { frontmatter, records, headers };
}

/**
 * 保存 CSV 数据（包含 frontmatter）
 */
function saveCSVWithFrontmatter(
  filePath: string,
  frontmatter: DeckFrontmatter | undefined,
  records: CardData[],
  headers?: string[]
): void {
  // 序列化 frontmatter
  const frontmatterStr = frontmatter ? serializeFrontMatter(frontmatter) : '';

  // 确定表头
  if (!headers || headers.length === 0) {
    // 从 records 和 frontmatter.fields 推断表头
    headers = ['label'];
    if (frontmatter?.fields && Array.isArray(frontmatter.fields)) {
      for (const field of frontmatter.fields) {
        if (field.name && typeof field.name === 'string') {
          headers.push(field.name);
        }
      }
    }
    headers.push('body');
  }

  // 确保所有 record 都有 headers 中的列
  for (const record of records) {
    for (const header of headers) {
      if (!(header in record)) {
        record[header] = '';
      }
    }
  }

  // 序列化 CSV
  const csvContent = stringify(records, {
    header: true,
    columns: headers
  });

  // 写入文件
  writeFileSync(filePath, frontmatterStr + csvContent, 'utf-8');
}

/**
 * 生成下一个 label
 */
function generateNextLabel(records: CardData[]): string {
  const maxLabel = records.reduce((max, record) => {
    const label = record.label ? parseInt(record.label, 10) : 0;
    return label > max ? label : max;
  }, 0);
  return (maxLabel + 1).toString();
}

/**
 * 卡牌 CRUD 操作
 */
export function cardCrud(params: CardCrudParams): CardCrudResult {
  const { csv_file, action, cards, label } = params;

  // 检查文件是否存在（create 操作可以不存在）
  if (action !== 'create' && !existsSync(csv_file)) {
    return {
      success: false,
      message: `文件不存在：${csv_file}`
    };
  }

  try {
    let frontmatter: DeckFrontmatter | undefined;
    let records: CardData[] = [];
    let headers: string[] = [];

    // 加载现有数据
    if (existsSync(csv_file)) {
      const data = loadCSVWithFrontmatter(csv_file);
      frontmatter = data.frontmatter;
      records = data.records;
      headers = data.headers;
    }

    // 执行操作
    switch (action) {
      case 'create': {
        const newCards = Array.isArray(cards) ? cards : (cards ? [cards] : []);
        for (const card of newCards) {
          if (!card.label) {
            card.label = generateNextLabel(records);
          }
          records.push(card);
        }
        saveCSVWithFrontmatter(csv_file, frontmatter, records, headers);
        return {
          success: true,
          message: `成功创建 ${newCards.length} 张卡牌`,
          cards: newCards,
          count: newCards.length
        };
      }

      case 'read': {
        const labelsToRead = Array.isArray(label) ? label : (label ? [label] : null);
        let resultCards: CardData[];

        if (labelsToRead && labelsToRead.length > 0) {
          resultCards = records.filter(r => labelsToRead.includes(r.label || ''));
        } else {
          resultCards = records;
        }

        return {
          success: true,
          message: `成功读取 ${resultCards.length} 张卡牌`,
          cards: resultCards,
          count: resultCards.length
        };
      }

      case 'update': {
        const labelsToUpdate = Array.isArray(label) ? label : (label ? [label] : null);
        const updateCards = Array.isArray(cards) ? cards : (cards ? [cards] : []);
        let updatedCount = 0;

        if (labelsToUpdate && labelsToUpdate.length > 0) {
          // 按 label 更新
          for (const updateCard of updateCards) {
            const targetLabel = updateCard.label || labelsToUpdate[updatedCount % labelsToUpdate.length];
            const index = records.findIndex(r => r.label === targetLabel);
            if (index !== -1) {
              records[index] = { ...records[index], ...updateCard };
              updatedCount++;
            }
          }
        } else {
          // 按 cards 中的 label 更新
          for (const updateCard of updateCards) {
            if (updateCard.label) {
              const index = records.findIndex(r => r.label === updateCard.label);
              if (index !== -1) {
                records[index] = { ...records[index], ...updateCard };
                updatedCount++;
              }
            }
          }
        }

        saveCSVWithFrontmatter(csv_file, frontmatter, records, headers);
        return {
          success: true,
          message: `成功更新 ${updatedCount} 张卡牌`,
          cards: updateCards,
          count: updatedCount
        };
      }

      case 'delete': {
        const labelsToDelete = Array.isArray(label) ? label : (label ? [label] : null);
        let deletedCount = 0;

        if (labelsToDelete && labelsToDelete.length > 0) {
          const beforeCount = records.length;
          records = records.filter(r => !labelsToDelete.includes(r.label || ''));
          deletedCount = beforeCount - records.length;
        } else if (cards) {
          const cardsToDelete = Array.isArray(cards) ? cards : [cards];
          const beforeCount = records.length;
          records = records.filter(r =>
            !cardsToDelete.some(c => c.label && r.label === c.label)
          );
          deletedCount = beforeCount - records.length;
        }

        saveCSVWithFrontmatter(csv_file, frontmatter, records, headers);
        return {
          success: true,
          message: `成功删除 ${deletedCount} 张卡牌`,
          count: deletedCount
        };
      }

      default:
        return {
          success: false,
          message: `未知操作：${action}`
        };
    }
  } catch (error) {
    return {
      success: false,
      message: `操作失败：${error instanceof Error ? error.message : '未知错误'}`
    };
  }
}