/**
 * 메일 관리 시스템 API 클라이언트
 * 파일 기반 메일 계정 및 템플릿 관리
 */

// ============================================
// 타입 정의
// ============================================

export interface MailAccount {
  id: string;
  name: string;
  email: string;
  smtpHost: string;
  smtpPort: number;
  smtpSecure: boolean;
  smtpUsername: string;
  smtpPassword: string; // 암호화된 상태
  dailyLimit: number;
  status: 'active' | 'inactive';
  createdAt: string;
  updatedAt: string;
}

export interface CreateMailAccountDto {
  name: string;
  email: string;
  smtpHost: string;
  smtpPort: number;
  smtpSecure: boolean;
  smtpUsername: string;
  smtpPassword: string;
  dailyLimit?: number;
}

export interface UpdateMailAccountDto extends Partial<CreateMailAccountDto> {
  status?: 'active' | 'inactive';
}

export interface MailComponent {
  id: string;
  type: 'text' | 'button' | 'image' | 'spacer';
  content?: string;
  text?: string;
  url?: string;
  src?: string;
  height?: number;
  styles?: Record<string, string>;
}

export interface MailTemplate {
  id: string;
  name: string;
  subject: string;
  components: MailComponent[];
  category?: string;
  createdAt: string;
  updatedAt: string;
}

export interface CreateMailTemplateDto {
  name: string;
  subject: string;
  components: MailComponent[];
  category?: string;
}

export interface UpdateMailTemplateDto extends Partial<CreateMailTemplateDto> {}

export interface SendMailDto {
  accountId: string;
  templateId?: string;
  to: string[]; // 수신자 이메일 배열
  subject: string;
  variables?: Record<string, string>; // 템플릿 변수 치환
  customHtml?: string; // 템플릿 없이 직접 HTML 작성 시
}

export interface MailSendResult {
  success: boolean;
  messageId?: string;
  error?: string;
}

// ============================================
// API 기본 설정
// ============================================

const API_BASE_URL = '/api/mail';

async function fetchApi<T>(
  endpoint: string,
  options: RequestInit = {}
): Promise<T> {
  const response = await fetch(`${API_BASE_URL}${endpoint}`, {
    ...options,
    headers: {
      'Content-Type': 'application/json',
      ...options.headers,
    },
  });

  if (!response.ok) {
    const error = await response.json().catch(() => ({ message: 'Unknown error' }));
    throw new Error(error.message || `HTTP ${response.status}`);
  }

  const result = await response.json();
  
  // 백엔드가 { success: true, data: ... } 형식으로 반환하는 경우 처리
  if (result.success && result.data !== undefined) {
    return result.data as T;
  }
  
  return result as T;
}

// ============================================
// 메일 계정 API
// ============================================

/**
 * 전체 메일 계정 목록 조회
 */
export async function getMailAccounts(): Promise<MailAccount[]> {
  return fetchApi<MailAccount[]>('/accounts');
}

/**
 * 특정 메일 계정 조회
 */
export async function getMailAccount(id: string): Promise<MailAccount> {
  return fetchApi<MailAccount>(`/accounts/${id}`);
}

/**
 * 메일 계정 생성
 */
export async function createMailAccount(
  data: CreateMailAccountDto
): Promise<MailAccount> {
  return fetchApi<MailAccount>('/accounts', {
    method: 'POST',
    body: JSON.stringify(data),
  });
}

/**
 * 메일 계정 수정
 */
export async function updateMailAccount(
  id: string,
  data: UpdateMailAccountDto
): Promise<MailAccount> {
  return fetchApi<MailAccount>(`/accounts/${id}`, {
    method: 'PUT',
    body: JSON.stringify(data),
  });
}

/**
 * 메일 계정 삭제
 */
export async function deleteMailAccount(id: string): Promise<{ success: boolean }> {
  return fetchApi<{ success: boolean }>(`/accounts/${id}`, {
    method: 'DELETE',
  });
}

/**
 * SMTP 연결 테스트
 */
export async function testMailConnection(id: string): Promise<{
  success: boolean;
  message: string;
}> {
  return fetchApi<{ success: boolean; message: string }>(
    `/accounts/${id}/test-connection`,
    {
      method: 'POST',
    }
  );
}

// ============================================
// 메일 템플릿 API
// ============================================

/**
 * 전체 메일 템플릿 목록 조회
 */
export async function getMailTemplates(): Promise<MailTemplate[]> {
  return fetchApi<MailTemplate[]>('/templates-file');
}

/**
 * 특정 메일 템플릿 조회
 */
export async function getMailTemplate(id: string): Promise<MailTemplate> {
  return fetchApi<MailTemplate>(`/templates-file/${id}`);
}

/**
 * 메일 템플릿 생성
 */
export async function createMailTemplate(
  data: CreateMailTemplateDto
): Promise<MailTemplate> {
  return fetchApi<MailTemplate>('/templates-file', {
    method: 'POST',
    body: JSON.stringify(data),
  });
}

/**
 * 메일 템플릿 수정
 */
export async function updateMailTemplate(
  id: string,
  data: UpdateMailTemplateDto
): Promise<MailTemplate> {
  return fetchApi<MailTemplate>(`/templates-file/${id}`, {
    method: 'PUT',
    body: JSON.stringify(data),
  });
}

/**
 * 메일 템플릿 삭제
 */
export async function deleteMailTemplate(id: string): Promise<{ success: boolean }> {
  return fetchApi<{ success: boolean }>(`/templates-file/${id}`, {
    method: 'DELETE',
  });
}

/**
 * 메일 템플릿 미리보기 (샘플 데이터)
 */
export async function previewMailTemplate(
  id: string,
  sampleData?: Record<string, string>
): Promise<{ html: string }> {
  return fetchApi<{ html: string }>(`/templates-file/${id}/preview`, {
    method: 'POST',
    body: JSON.stringify({ sampleData }),
  });
}

// ============================================
// 메일 발송 API (간단한 버전 - 쿼리 제외)
// ============================================

/**
 * 메일 발송 (단건 또는 소규모 발송)
 */
export async function sendMail(data: SendMailDto): Promise<MailSendResult> {
  return fetchApi<MailSendResult>('/send/simple', {
    method: 'POST',
    body: JSON.stringify(data),
  });
}

/**
 * 템플릿 변수 추출 (템플릿에서 {변수명} 형식 추출)
 */
export function extractTemplateVariables(template: MailTemplate): string[] {
  const variableRegex = /\{(\w+)\}/g;
  const variables = new Set<string>();

  // subject에서 추출
  const subjectMatches = template.subject.matchAll(variableRegex);
  for (const match of subjectMatches) {
    variables.add(match[1]);
  }

  // 컴포넌트 content에서 추출
  template.components.forEach((component) => {
    if (component.content) {
      const contentMatches = component.content.matchAll(variableRegex);
      for (const match of contentMatches) {
        variables.add(match[1]);
      }
    }
    if (component.text) {
      const textMatches = component.text.matchAll(variableRegex);
      for (const match of textMatches) {
        variables.add(match[1]);
      }
    }
  });

  return Array.from(variables);
}

/**
 * 템플릿을 HTML로 렌더링 (프론트엔드 미리보기용)
 */
export function renderTemplateToHtml(
  template: MailTemplate,
  variables?: Record<string, string>
): string {
  let html = '<div style="max-width: 600px; margin: 0 auto; font-family: Arial, sans-serif;">';

  template.components.forEach((component) => {
    switch (component.type) {
      case 'text':
        let content = component.content || '';
        if (variables) {
          Object.entries(variables).forEach(([key, value]) => {
            content = content.replace(new RegExp(`\\{${key}\\}`, 'g'), value);
          });
        }
        html += `<div style="${styleObjectToString(component.styles)}">${content}</div>`;
        break;

      case 'button':
        let buttonText = component.text || 'Button';
        if (variables) {
          Object.entries(variables).forEach(([key, value]) => {
            buttonText = buttonText.replace(new RegExp(`\\{${key}\\}`, 'g'), value);
          });
        }
        html += `
          <a href="${component.url || '#'}" style="
            display: inline-block;
            padding: 12px 24px;
            background-color: #007bff;
            color: white;
            text-decoration: none;
            border-radius: 4px;
            ${styleObjectToString(component.styles)}
          ">${buttonText}</a>
        `;
        break;

      case 'image':
        html += `<img src="${component.src || ''}" style="max-width: 100%; ${styleObjectToString(component.styles)}" />`;
        break;

      case 'spacer':
        html += `<div style="height: ${component.height || 20}px;"></div>`;
        break;
    }
  });

  html += '</div>';
  return html;
}

function styleObjectToString(styles?: Record<string, string>): string {
  if (!styles) return '';
  return Object.entries(styles)
    .map(([key, value]) => `${camelToKebab(key)}: ${value}`)
    .join('; ');
}

function camelToKebab(str: string): string {
  return str.replace(/([a-z0-9])([A-Z])/g, '$1-$2').toLowerCase();
}

// ============================================
// 📥 메일 수신 API (Step 2)
// ============================================

export interface ReceivedMail {
  id: string;
  messageId: string;
  from: string;
  to: string;
  subject: string;
  date: string;
  preview: string;
  isRead: boolean;
  hasAttachments: boolean;
}

export interface MailDetail extends ReceivedMail {
  htmlBody: string;
  textBody: string;
  cc?: string;
  bcc?: string;
  attachments: Array<{
    filename: string;
    contentType: string;
    size: number;
  }>;
}

/**
 * 받은 메일 목록 조회
 */
export async function getReceivedMails(
  accountId: string,
  limit: number = 50
): Promise<ReceivedMail[]> {
  return fetchApi<ReceivedMail[]>(`/mail/receive/${accountId}?limit=${limit}`);
}

/**
 * 메일 상세 조회
 */
export async function getMailDetail(
  accountId: string,
  seqno: number
): Promise<MailDetail> {
  return fetchApi<MailDetail>(`/mail/receive/${accountId}/${seqno}`);
}

/**
 * 메일을 읽음으로 표시
 */
export async function markMailAsRead(
  accountId: string,
  seqno: number
): Promise<{ success: boolean; message: string }> {
  return fetchApi(`/mail/receive/${accountId}/${seqno}/mark-read`, {
    method: 'POST',
  });
}

/**
 * IMAP 연결 테스트
 */
export async function testImapConnection(
  accountId: string
): Promise<{ success: boolean; message: string }> {
  return fetchApi(`/mail/receive/${accountId}/test-imap`, {
    method: 'POST',
  });
}