'use server';

import fs from 'fs';
import path from 'path';
import handlebars from 'handlebars';
import i18next from 'i18next';
import resourcesToBackend from 'i18next-resources-to-backend';
import { getOptions } from '@/i18n/settings';

// Types
export interface TemplateFile {
  name: string;
  content: string;
  lastModified: string;
  path: string;
}

interface UpdateTemplateRequest {
  name: string;
  content: string;
}

interface TemplateValidationResult {
  isValid: boolean;
  errors: string[];
  warnings: string[];
}

// Configuration
const baseDir = path.join(process.cwd(), 'lib', 'mail');
const templatesDir = path.join(baseDir, 'templates');

let initialized = false;

function getFilePath(name: string): string {
  const fileName = name.endsWith('.hbs') ? name : `${name}.hbs`;
  return path.join(templatesDir, fileName);
}

// Initialization
async function initializeAsync(): Promise<void> {
  if (initialized) return;

  try {
    // i18next 초기화 (서버 사이드)
    if (!i18next.isInitialized) {
      await i18next
        .use(resourcesToBackend((language: string, namespace: string) => 
          import(`@/i18n/locales/${language}/${namespace}.json`)
        ))
        .init(getOptions());
    }

    // Handlebars 헬퍼 등록
    registerHandlebarsHelpers();
    initialized = true;
  } catch (error) {
    console.error('Failed to initialize TemplateService:', error);
    // 초기화 실패해도 헬퍼는 등록
    registerHandlebarsHelpers();
    initialized = true;
  }
}

async function ensureInitialized(): Promise<void> {
  if (initialized) return;
  await initializeAsync();
}

function registerHandlebarsHelpers(): void {
  // i18n 번역 헬퍼
  handlebars.registerHelper('t', function(key: string, options: { hash?: Record<string, unknown> }) {
    return i18next.t(key, options.hash || {});
  });

  // 날짜 포맷 헬퍼
  handlebars.registerHelper('formatDate', function(date: Date | string, format?: string) {
    if (!date) return '';
    const d = new Date(date);
    if (isNaN(d.getTime())) return '';
    
    if (!format || format === 'date') {
      return d.toISOString().split('T')[0];
    }
    
    if (format === 'datetime') {
      return d.toLocaleString('ko-KR', { 
        year: 'numeric', 
        month: '2-digit', 
        day: '2-digit', 
        hour: '2-digit', 
        minute: '2-digit' 
      });
    }
    
    return d.toLocaleDateString('ko-KR');
  });

  // 숫자 포맷 헬퍼
  handlebars.registerHelper('formatNumber', function(number: number | string) {
    if (typeof number === 'string') {
      number = parseFloat(number);
    }
    if (isNaN(number)) return '';
    return number.toLocaleString('ko-KR');
  });

  // 조건부 렌더링 헬퍼
  handlebars.registerHelper('ifEquals', function(this: unknown, arg1: unknown, arg2: unknown, options: { fn: (context: unknown) => string; inverse: (context: unknown) => string }) {
    return (arg1 === arg2) ? options.fn(this) : options.inverse(this);
  });

  // 배열 길이 확인 헬퍼
  handlebars.registerHelper('ifArrayLength', function(this: unknown, array: unknown[], length: number, options: { fn: (context: unknown) => string; inverse: (context: unknown) => string }) {
    return (Array.isArray(array) && array.length === length) ? options.fn(this) : options.inverse(this);
  });
}

// Validation
function validateTemplate(content: string): TemplateValidationResult {
  const errors: string[] = [];
  const warnings: string[] = [];

  try {
    // Handlebars 문법 검사
    handlebars.compile(content);
  } catch (error) {
    if (error instanceof Error) {
      errors.push(`Handlebars 문법 오류: ${error.message}`);
    }
  }

  // 일반적인 문제 확인
  if (content.trim().length === 0) {
    errors.push('템플릿 내용이 비어있습니다.');
  }

  // 위험한 패턴 확인
  if (content.includes('<script>')) {
    warnings.push('스크립트 태그가 포함되어 있습니다. 보안에 주의하세요.');
  }

  return {
    isValid: errors.length === 0,
    errors,
    warnings
  };
}

// Core Functions
async function getTemplateList(): Promise<TemplateFile[]> {
  try {
    if (!fs.existsSync(templatesDir)) {
      return [];
    }

    const files = fs.readdirSync(templatesDir).filter(file => file.endsWith('.hbs'));
    const allTemplates: TemplateFile[] = [];
    
    for (const file of files) {
      const filePath = path.join(templatesDir, file);
      
      try {
        const stats = fs.statSync(filePath);
        const content = fs.readFileSync(filePath, 'utf8');
        
        allTemplates.push({
          name: file.replace('.hbs', ''),
          content,
          lastModified: stats.mtime.toISOString(),
          path: filePath
        });
      } catch (fileError) {
        console.error(`❌ 파일 읽기 실패: ${filePath}`, fileError);
      }
    }

    return allTemplates.sort((a, b) => a.name.localeCompare(b.name));
  } catch (error) {
    console.error('Error getting template list:', error);
    throw new Error('템플릿 목록을 가져오는데 실패했습니다.');
  }
}

async function getTemplate(name: string): Promise<TemplateFile | null> {
  try {
    const filePath = getFilePath(name);
    
    if (!fs.existsSync(filePath)) {
      return null;
    }

    const stats = fs.statSync(filePath);
    const content = fs.readFileSync(filePath, 'utf8');

    return {
      name: name.replace('.hbs', ''),
      content,
      lastModified: stats.mtime.toISOString(),
      path: filePath
    };
  } catch (error) {
    console.error(`❌ 템플릿 조회 실패 ${name}:`, error);
    throw new Error(`템플릿 ${name}을 가져오는데 실패했습니다.`);
  }
}

async function updateTemplate(request: UpdateTemplateRequest): Promise<TemplateFile> {
  try {
    const { name, content } = request;
    
    // 템플릿 유효성 검사
    const validation = validateTemplate(content);
    if (!validation.isValid) {
      throw new Error(`템플릿 유효성 검사 실패: ${validation.errors.join(', ')}`);
    }

    const filePath = getFilePath(name);
    
    if (!fs.existsSync(filePath)) {
      throw new Error(`템플릿 ${name}이 존재하지 않습니다.`);
    }

    fs.writeFileSync(filePath, content, 'utf8');
    
    const stats = fs.statSync(filePath);
    
    return {
      name: name.replace('.hbs', ''),
      content,
      lastModified: stats.mtime.toISOString(),
      path: filePath
    };
  } catch (error) {
    console.error('Error updating template:', error);
    if (error instanceof Error) {
      throw error;
    }
    throw new Error('템플릿 수정에 실패했습니다.');
  }
}

async function searchTemplates(query: string): Promise<TemplateFile[]> {
  try {
    const allTemplates = await getTemplateList();
    const lowerQuery = query.toLowerCase();
    
    return allTemplates.filter(template => 
      template.name.toLowerCase().includes(lowerQuery) ||
      template.content.toLowerCase().includes(lowerQuery)
    );
  } catch (error) {
    console.error('Error searching templates:', error);
    throw new Error('템플릿 검색에 실패했습니다.');
  }
}

async function previewTemplate(
  name: string,
  data?: Record<string, unknown>
): Promise<string> {
  try {
    // 초기화 대기
    await ensureInitialized();

    const template = await getTemplate(name);
    if (!template) {
      throw new Error(`템플릿 ${name}이 존재하지 않습니다.`);
    }

    // 템플릿 컴파일
    const compiledTemplate = handlebars.compile(template.content);
    const content = compiledTemplate(data || {});

    return content;
  } catch (error) {
    console.error('Error previewing template:', error);
    throw new Error('템플릿 미리보기 생성에 실패했습니다.');
  }
}

// Server Actions
export async function getTemplatesAction(search?: string) {
  try {
    let templates;
    
    if (search) {
      templates = await searchTemplates(search);
    } else {
      templates = await getTemplateList();
    }

    return {
      success: true,
      data: templates
    };
  } catch (error) {
    return {
      success: false,
      error: error instanceof Error ? error.message : '템플릿 목록을 가져오는데 실패했습니다.'
    };
  }
}

export async function getTemplateAction(name: string) {
  try {
    const template = await getTemplate(name);

    if (!template) {
      return {
        success: false,
        error: '템플릿을 찾을 수 없습니다.'
      };
    }

    return {
      success: true,
      data: template
    };
  } catch (error) {
    return {
      success: false,
      error: error instanceof Error ? error.message : '템플릿을 가져오는데 실패했습니다.'
    };
  }
}

export async function updateTemplateAction(name: string, content: string) {
  try {
    if (!content) {
      return {
        success: false,
        error: '템플릿 내용이 필요합니다.'
      };
    }

    const template = await updateTemplate({
      name,
      content
    });

    return {
      success: true,
      data: template
    };
  } catch (error) {
    return {
      success: false,
      error: error instanceof Error ? error.message : '템플릿 수정에 실패했습니다.'
    };
  }
}

export async function previewTemplateAction(
  name: string, 
  data?: Record<string, unknown>
) {
  try {
    if (!name) {
      return {
        success: false,
        error: '템플릿 이름이 필요합니다.'
      };
    }

    const result = await previewTemplate(name, data);

    return {
      success: true,
      data: {
        html: result
      }
    };
  } catch (error) {
    return {
      success: false,
      error: error instanceof Error ? error.message : '미리보기 생성에 실패했습니다.'
    };
  }
}