import { EmailTemplate } from '../types';

// Fallback for crypto.randomUUID in non-secure (HTTP) contexts
export const generateUUID = () => {
  if (typeof crypto !== 'undefined' && crypto.randomUUID) {
    try {
      return crypto.randomUUID();
    } catch (e) {
      // Fallback if it exists but fails
    }
  }
  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
    const r = Math.random() * 16 | 0;
    const v = c === 'x' ? r : (r & 0x3 | 0x8);
    return v.toString(16);
  });
};

export const generateTemplateKey = (name: string): string => {
  return name.trim().toLowerCase().replace(/\s+/g, '_').replace(/[^a-z0-9_]/g, '');
};

export const generateSQL = (template: EmailTemplate): string => {
  const fullHtml = `${template.header}${template.body}${template.footer}`.replace(/'/g, "''");
  const header = template.header.replace(/'/g, "''");
  const body = template.body.replace(/'/g, "''");
  const footer = template.footer.replace(/'/g, "''");
  const subject = template.subject.replace(/'/g, "''");
  const vars = JSON.stringify(template.variables).replace(/'/g, "''");
  const key = generateTemplateKey(template.name);
  const name = template.name.replace(/'/g, "''");
  const desc = (template.description || '').replace(/'/g, "''");

  return `INSERT INTO email_templates (id, template_key, name, description, subject, header_html, body_html, footer_html, full_html, required_variables)
VALUES ('${template.id}', '${key}', '${name}', '${desc}', '${subject}', '${header}', '${body}', '${footer}', '${fullHtml}', '${vars}')
ON DUPLICATE KEY UPDATE 
    template_key = VALUES(template_key),
    name = VALUES(name),
    description = VALUES(description),
    subject = VALUES(subject),
    header_html = VALUES(header_html),
    body_html = VALUES(body_html),
    footer_html = VALUES(footer_html),
    full_html = VALUES(full_html),
    required_variables = VALUES(required_variables);`;
};

export const generateSelectSQL = (template: EmailTemplate): string => {
  const key = generateTemplateKey(template.name);
  return `SELECT * FROM email_templates WHERE template_key = '${key}';`;
};

export const generateN8nCode = (template: EmailTemplate): string => {
  const varsMap = template.variables.map(v => `  "${v}": "REPLACE_WITH_VALUE"`).join(',\n');
  const hasVars = template.variables.length > 0;

  return `// Nodo Code n8n - Popolatore Template
for (const item of items) {
  const templateHtml = item.json.full_html;
  const templateSubject = item.json.subject;

  const replacements = {
${hasVars ? varsMap : '  // Nessuna variabile rilevata'}
  };

  let finalHtml = templateHtml;
  let finalSubject = templateSubject;
  
  for (const [key, value] of Object.entries(replacements)) {
    const regex = new RegExp('{{' + key + '}}', 'g');
    finalHtml = finalHtml.replace(regex, value);
    if (finalSubject) {
      finalSubject = finalSubject.replace(regex, value);
    }
  }

  item.json.processed_html = finalHtml;
  item.json.processed_subject = finalSubject;
}
return items;`;
};

export const getTemplates = async (): Promise<EmailTemplate[]> => {
  console.log("Fetching templates from /api/templates...");
  const response = await fetch('/api/templates');
  if (!response.ok) {
    const errorBody = await response.text();
    throw new Error(`Errore API (${response.status}): ${errorBody || response.statusText}`);
  }
  return await response.json();
};

export const saveTemplate = async (template: EmailTemplate): Promise<void> => {
  console.log("Saving template to /api/templates...", template.name);
  const response = await fetch('/api/templates', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
    },
    body: JSON.stringify(template),
  });
  
  if (!response.ok) {
    let errorMessage = `Errore HTTP ${response.status}`;
    try {
        const errorData = await response.json();
        errorMessage = errorData.details || errorData.error || errorMessage;
    } catch (e) {
        const textError = await response.text();
        if (textError) errorMessage = textError;
    }
    throw new Error(errorMessage);
  }
};

export const deleteTemplate = async (id: string): Promise<void> => {
  const response = await fetch(`/api/templates/${id}`, {
    method: 'DELETE',
  });
  if (!response.ok) throw new Error('Eliminazione fallita');
};