/**
 * SEO Template Engine
 *
 * Handles template selection, variable injection, and content generation
 * for different page types (state, city, category, brand, product, search).
 */

import { getAllSettings, getSetting } from './settings';

// Page types supported by the template engine
export type PageType = 'state' | 'city' | 'category' | 'brand' | 'product' | 'search';

// Template keys mapping
export const TEMPLATE_KEYS: Record<PageType, string> = {
  state: 'state_page_template',
  city: 'city_page_template',
  category: 'category_page_template',
  brand: 'brand_page_template',
  product: 'product_page_template',
  search: 'search_results_template',
};

// Sample mock data for previews
export const MOCK_DATA: Record<PageType, Record<string, any>> = {
  state: {
    state_name: 'Arizona',
    state_code: 'AZ',
    state_code_lower: 'az',
    dispensary_count: 156,
    product_count: 12450,
    brand_count: 287,
    category_count: 8,
    top_brands: ['Raw Garden', 'Stiiizy', 'Select', 'Pax', 'Bloom'],
    top_categories: ['Flower', 'Vape', 'Edibles', 'Concentrate', 'Pre-rolls'],
    avg_price: 42.50,
    last_updated: new Date().toISOString().split('T')[0],
  },
  city: {
    city_name: 'Phoenix',
    state_name: 'Arizona',
    state_code: 'AZ',
    dispensary_count: 45,
    product_count: 3200,
    brand_count: 120,
    nearby_cities: ['Scottsdale', 'Tempe', 'Mesa', 'Glendale'],
    popular_dispensaries: ['Harvest', 'Curaleaf', 'Zen Leaf'],
    avg_price: 40.00,
  },
  category: {
    category_name: 'Flower',
    category_slug: 'flower',
    product_count: 4500,
    brand_count: 95,
    state_name: 'Arizona',
    avg_price: 35.00,
    top_strains: ['Blue Dream', 'OG Kush', 'Girl Scout Cookies'],
    subcategories: ['Indica', 'Sativa', 'Hybrid'],
  },
  brand: {
    brand_name: 'Raw Garden',
    brand_slug: 'raw-garden',
    product_count: 156,
    state_presence: ['AZ', 'CA', 'NV', 'CO'],
    store_count: 89,
    avg_price: 45.00,
    categories: ['Concentrate', 'Vape', 'Live Resin'],
    description: 'Premium cannabis products from California',
  },
  product: {
    product_name: 'Blue Dream Cartridge',
    brand_name: 'Select',
    category: 'Vape',
    thc_percent: 85.5,
    cbd_percent: 0.5,
    price: 45.00,
    dispensary_name: 'Harvest HOC',
    dispensary_city: 'Phoenix',
    state_name: 'Arizona',
    in_stock: true,
  },
  search: {
    query: 'live resin',
    result_count: 245,
    product_results: 180,
    dispensary_results: 45,
    brand_results: 20,
    state_name: 'Arizona',
    top_categories: ['Concentrate', 'Vape'],
  },
};

/**
 * Apply template variables to a template string
 * Replaces {{variable}} with values from data object
 *
 * Rules:
 * - Replace {{variable}} occurrences
 * - Leave unknown variables unchanged
 * - Prevent undefined values (replace with empty string)
 * - Support arrays by joining with comma
 */
export function applyTemplateVariables(
  template: string,
  data: Record<string, any>
): string {
  if (!template) return '';

  let result = template;

  // Find all {{variable}} patterns
  const variablePattern = /\{\{(\w+)\}\}/g;
  let match;

  while ((match = variablePattern.exec(template)) !== null) {
    const fullMatch = match[0];
    const variableName = match[1];

    if (variableName in data) {
      let value = data[variableName];

      // Handle different value types
      if (value === undefined || value === null) {
        value = '';
      } else if (Array.isArray(value)) {
        value = value.join(', ');
      } else if (typeof value === 'object') {
        value = JSON.stringify(value);
      } else {
        value = String(value);
      }

      // Replace all occurrences of this variable
      result = result.split(fullMatch).join(value);
    }
    // Leave unknown variables unchanged
  }

  return result;
}

/**
 * Get the correct template for a page type
 * Uses case-insensitive matching
 */
export async function getTemplateForPageType(pageType: string): Promise<string> {
  const normalizedType = pageType.toLowerCase().trim() as PageType;
  const templateKey = TEMPLATE_KEYS[normalizedType];

  if (!templateKey) {
    console.warn(`[TemplateEngine] Unknown page type: ${pageType}, falling back to state template`);
    return getSetting('state_page_template');
  }

  return getSetting(templateKey);
}

/**
 * Get regeneration template
 */
export async function getRegenerationTemplate(): Promise<string> {
  return getSetting('regeneration_template');
}

/**
 * Generate content for a page using the appropriate template
 */
export async function generatePageContent(
  pageType: string,
  data: Record<string, any>
): Promise<{
  content: string;
  templateUsed: string;
  variablesApplied: string[];
}> {
  const template = await getTemplateForPageType(pageType);
  const content = applyTemplateVariables(template, data);

  // Extract which variables were actually used
  const variablePattern = /\{\{(\w+)\}\}/g;
  const variablesInTemplate: string[] = [];
  let match;
  while ((match = variablePattern.exec(template)) !== null) {
    if (!variablesInTemplate.includes(match[1])) {
      variablesInTemplate.push(match[1]);
    }
  }

  const variablesApplied = variablesInTemplate.filter(v => v in data);

  return {
    content,
    templateUsed: TEMPLATE_KEYS[pageType.toLowerCase() as PageType] || 'state_page_template',
    variablesApplied,
  };
}

/**
 * Generate a preview with mock data
 */
export async function generatePreview(
  pageType: string,
  customTemplate?: string
): Promise<{
  preview: string;
  template: string;
  mockData: Record<string, any>;
  availableVariables: string[];
}> {
  const normalizedType = (pageType?.toLowerCase().trim() || 'state') as PageType;
  const template = customTemplate || await getTemplateForPageType(normalizedType);
  const mockData = MOCK_DATA[normalizedType] || MOCK_DATA.state;

  const preview = applyTemplateVariables(template, mockData);

  return {
    preview,
    template,
    mockData,
    availableVariables: Object.keys(mockData),
  };
}

/**
 * Regenerate content using regeneration template
 */
export async function regenerateContent(
  pageType: string,
  originalContent: string,
  newData: Record<string, any>,
  improvementAreas?: string[]
): Promise<{
  content: string;
  regenerationPrompt: string;
}> {
  const regenerationTemplate = await getRegenerationTemplate();
  const settings = await getAllSettings();

  // Build regeneration context
  const regenerationData = {
    ...newData,
    original_content: originalContent,
    page_type: pageType,
    improvement_areas: improvementAreas?.join(', ') || 'SEO keywords, local relevance, data freshness',
    tone: settings.tone_voice || 'informational',
    length: settings.default_content_length || 'medium',
  };

  const regenerationPrompt = applyTemplateVariables(regenerationTemplate, regenerationData);

  // Generate new content using the page template
  const pageTemplate = await getTemplateForPageType(pageType);
  const content = applyTemplateVariables(pageTemplate, newData);

  return {
    content,
    regenerationPrompt,
  };
}

/**
 * Get all available templates and their metadata
 */
export async function getAllTemplates(): Promise<Record<string, {
  key: string;
  template: string;
  description: string;
  availableVariables: string[];
}>> {
  const settings = await getAllSettings();

  return {
    state: {
      key: 'state_page_template',
      template: settings.state_page_template || '',
      description: 'Template for state landing pages (e.g., "Arizona Dispensaries")',
      availableVariables: Object.keys(MOCK_DATA.state),
    },
    city: {
      key: 'city_page_template',
      template: settings.city_page_template || '',
      description: 'Template for city landing pages (e.g., "Phoenix Dispensaries")',
      availableVariables: Object.keys(MOCK_DATA.city),
    },
    category: {
      key: 'category_page_template',
      template: settings.category_page_template || '',
      description: 'Template for category pages (e.g., "Flower", "Edibles")',
      availableVariables: Object.keys(MOCK_DATA.category),
    },
    brand: {
      key: 'brand_page_template',
      template: settings.brand_page_template || '',
      description: 'Template for brand pages (e.g., "Raw Garden Products")',
      availableVariables: Object.keys(MOCK_DATA.brand),
    },
    product: {
      key: 'product_page_template',
      template: settings.product_page_template || '',
      description: 'Template for individual product pages',
      availableVariables: Object.keys(MOCK_DATA.product),
    },
    search: {
      key: 'search_results_template',
      template: settings.search_results_template || '',
      description: 'Template for search results pages',
      availableVariables: Object.keys(MOCK_DATA.search),
    },
    regeneration: {
      key: 'regeneration_template',
      template: settings.regeneration_template || '',
      description: 'Template used when regenerating/improving existing content',
      availableVariables: ['original_content', 'page_type', 'improvement_areas', 'tone', 'length', '...page-specific variables'],
    },
  };
}

/**
 * Validate a template string
 */
export function validateTemplate(template: string): {
  valid: boolean;
  variables: string[];
  unknownVariables: string[];
  errors: string[];
} {
  const errors: string[] = [];
  const variables: string[] = [];

  // Find all variables
  const variablePattern = /\{\{(\w+)\}\}/g;
  let match;
  while ((match = variablePattern.exec(template)) !== null) {
    if (!variables.includes(match[1])) {
      variables.push(match[1]);
    }
  }

  // Check for unclosed brackets
  const openBrackets = (template.match(/\{\{/g) || []).length;
  const closeBrackets = (template.match(/\}\}/g) || []).length;
  if (openBrackets !== closeBrackets) {
    errors.push('Mismatched template brackets: {{ and }} counts do not match');
  }

  // Check for empty variable names
  if (template.includes('{{}}')) {
    errors.push('Empty variable name found: {{}}');
  }

  // Get all known variables
  const allKnownVariables = new Set<string>();
  Object.values(MOCK_DATA).forEach(data => {
    Object.keys(data).forEach(key => allKnownVariables.add(key));
  });
  allKnownVariables.add('original_content');
  allKnownVariables.add('page_type');
  allKnownVariables.add('improvement_areas');
  allKnownVariables.add('tone');
  allKnownVariables.add('length');

  const unknownVariables = variables.filter(v => !allKnownVariables.has(v));

  return {
    valid: errors.length === 0,
    variables,
    unknownVariables,
    errors,
  };
}