import { z } from 'zod';

/**
 * Types of templates that can be generated
 */
export type TemplateType = 
  | 'collection' 
  | 'field' 
  | 'global' 
  | 'config' 
  | 'access-control'
  | 'hook'
  | 'endpoint'
  | 'plugin'
  | 'block'
  | 'migration';

/**
 * Validation schema for template options
 */
const templateOptionsSchema = z.record(z.any());

/**
 * Generate a template for Payload CMS 3 based on the template type and options
 * @param templateType The type of template to generate
 * @param options Options for the template
 * @returns The generated code as a string
 */
export function generateTemplate(templateType: TemplateType, options: Record<string, any>): string {
  // Validate options
  const validationResult = templateOptionsSchema.safeParse(options);
  if (!validationResult.success) {
    throw new Error(`Invalid template options: ${JSON.stringify(validationResult.error.format())}`);
  }

  // Generate the template based on the type
  switch (templateType) {
    case 'collection':
      return generateCollectionTemplate(options);
    case 'field':
      return generateFieldTemplate(options);
    case 'global':
      return generateGlobalTemplate(options);
    case 'config':
      return generateConfigTemplate(options);
    case 'access-control':
      return generateAccessControlTemplate(options);
    case 'hook':
      return generateHookTemplate(options);
    case 'endpoint':
      return generateEndpointTemplate(options);
    case 'plugin':
      return generatePluginTemplate(options);
    case 'block':
      return generateBlockTemplate(options);
    case 'migration':
      return generateMigrationTemplate(options);
    default:
      throw new Error(`Unsupported template type: ${templateType}`);
  }
}

/**
 * Generate a collection template for Payload CMS 3
 * @param options Collection options
 * @returns The generated collection code
 */
function generateCollectionTemplate(options: Record<string, any>): string {
  const {
    slug,
    fields = [],
    auth = false,
    timestamps = true,
    admin = {},
    hooks = false,
    access = false,
    versions = false,
  } = options;

  if (!slug) {
    throw new Error('Collection slug is required');
  }

  // Generate fields code
  const fieldsCode = fields.length > 0
    ? fields.map((field: any) => {
        return generateFieldTemplate(field);
      }).join(',\n    ')
    : '';

  // Generate admin code
  const adminCode = Object.keys(admin).length > 0
    ? `\n  admin: {
    ${admin.useAsTitle ? `useAsTitle: '${admin.useAsTitle}',` : ''}
    ${admin.defaultColumns ? `defaultColumns: [${admin.defaultColumns.map((col: string) => `'${col}'`).join(', ')}],` : ''}
    ${admin.group ? `group: '${admin.group}',` : ''}
  },`
    : '';

  // Generate hooks code
  const hooksCode = hooks
    ? `\n  hooks: {
    beforeOperation: [
      // Add your hooks here
    ],
    afterOperation: [
      // Add your hooks here
    ],
  },`
    : '';

  // Generate access code
  const accessCode = access
    ? `\n  access: {
    read: () => true,
    update: () => true,
    create: () => true,
    delete: () => true,
  },`
    : '';

  // Generate auth code
  const authCode = auth
    ? `\n  auth: {
    useAPIKey: true,
    tokenExpiration: 7200,
  },`
    : '';

  // Generate versions code
  const versionsCode = versions
    ? `\n  versions: {
    drafts: true,
  },`
    : '';

  return `import { CollectionConfig } from 'payload/types';

const ${slug.charAt(0).toUpperCase() + slug.slice(1)}: CollectionConfig = {
  slug: '${slug}',${adminCode}${authCode}${accessCode}${hooksCode}${versionsCode}
  ${timestamps ? 'timestamps: true,' : ''}
  fields: [
    ${fieldsCode}
  ],
};

export default ${slug.charAt(0).toUpperCase() + slug.slice(1)};`;
}

/**
 * Generate a field template for Payload CMS 3
 * @param options Field options
 * @returns The generated field code
 */
function generateFieldTemplate(options: Record<string, any>): string {
  const {
    name,
    type,
    required = false,
    unique = false,
    localized = false,
    access = false,
    admin = {},
    validation = false,
    defaultValue,
  } = options;

  if (!name || !type) {
    throw new Error('Field name and type are required');
  }

  // Generate admin code
  const adminCode = Object.keys(admin).length > 0
    ? `\n    admin: {
      ${admin.description ? `description: '${admin.description}',` : ''}
      ${admin.readOnly ? 'readOnly: true,' : ''}
    },`
    : '';

  // Generate access code
  const accessCode = access
    ? `\n    access: {
      read: () => true,
      update: () => true,
    },`
    : '';

  // Generate validation code
  const validationCode = validation
    ? `\n    validate: (value) => {
      if (value === undefined || value === null) {
        return '${name} is required';
      }
      return true;
    },`
    : '';

  // Generate default value code
  const defaultValueCode = defaultValue !== undefined
    ? `\n    defaultValue: ${typeof defaultValue === 'string' ? `'${defaultValue}'` : defaultValue},`
    : '';

  // Generate field-specific options based on type
  let fieldSpecificOptions = '';
  
  switch (type) {
    case 'text':
    case 'textarea':
    case 'email':
    case 'code':
      fieldSpecificOptions = `\n    minLength: 1,
    maxLength: 255,`;
      break;
    case 'number':
      fieldSpecificOptions = `\n    min: 0,
    max: 1000,`;
      break;
    case 'select':
      fieldSpecificOptions = `\n    options: [
      { label: 'Option 1', value: 'option1' },
      { label: 'Option 2', value: 'option2' },
    ],
    hasMany: false,`;
      break;
    case 'relationship':
      fieldSpecificOptions = `\n    relationTo: 'collection-name',
    hasMany: false,`;
      break;
    case 'array':
      fieldSpecificOptions = `\n    minRows: 0,
    maxRows: 10,
    fields: [
      {
        name: 'subField',
        type: 'text',
        required: true,
      },
    ],`;
      break;
    case 'blocks':
      fieldSpecificOptions = `\n    blocks: [
      {
        slug: 'block-name',
        fields: [
          {
            name: 'blockField',
            type: 'text',
            required: true,
          },
        ],
      },
    ],`;
      break;
  }

  return `{
    name: '${name}',
    type: '${type}',${required ? '\n    required: true,' : ''}${unique ? '\n    unique: true,' : ''}${localized ? '\n    localized: true,' : ''}${adminCode}${accessCode}${validationCode}${defaultValueCode}${fieldSpecificOptions}
  }`;
}

/**
 * Generate a global template for Payload CMS 3
 * @param options Global options
 * @returns The generated global code
 */
function generateGlobalTemplate(options: Record<string, any>): string {
  const {
    slug,
    fields = [],
    admin = {},
    access = false,
    versions = false,
  } = options;

  if (!slug) {
    throw new Error('Global slug is required');
  }

  // Generate fields code
  const fieldsCode = fields.length > 0
    ? fields.map((field: any) => {
        return generateFieldTemplate(field);
      }).join(',\n    ')
    : '';

  // Generate admin code
  const adminCode = Object.keys(admin).length > 0
    ? `\n  admin: {
    ${admin.group ? `group: '${admin.group}',` : ''}
  },`
    : '';

  // Generate access code
  const accessCode = access
    ? `\n  access: {
    read: () => true,
    update: () => true,
  },`
    : '';

  // Generate versions code
  const versionsCode = versions
    ? `\n  versions: {
    drafts: true,
  },`
    : '';

  return `import { GlobalConfig } from 'payload/types';

const ${slug.charAt(0).toUpperCase() + slug.slice(1)}: GlobalConfig = {
  slug: '${slug}',${adminCode}${accessCode}${versionsCode}
  fields: [
    ${fieldsCode}
  ],
};

export default ${slug.charAt(0).toUpperCase() + slug.slice(1)};`;
}

/**
 * Generate a config template for Payload CMS 3
 * @param options Config options
 * @returns The generated config code
 */
function generateConfigTemplate(options: Record<string, any>): string {
  const {
    serverURL = 'http://localhost:3000',
    collections = [],
    globals = [],
    admin = {},
    db = 'mongodb',
    plugins = [],
    typescript = true,
  } = options;

  // Generate collections code
  const collectionsCode = collections.length > 0
    ? collections.map((collection: string) => `import ${collection.charAt(0).toUpperCase() + collection.slice(1)} from './collections/${collection}';`).join('\n')
    : '';

  // Generate globals code
  const globalsCode = globals.length > 0
    ? globals.map((global: string) => `import ${global.charAt(0).toUpperCase() + global.slice(1)} from './globals/${global}';`).join('\n')
    : '';

  // Generate plugins code
  const pluginsCode = plugins.length > 0
    ? plugins.map((plugin: string) => {
        if (plugin === 'form-builder') {
          return `import formBuilder from '@payloadcms/plugin-form-builder';`;
        } else if (plugin === 'seo') {
          return `import seoPlugin from '@payloadcms/plugin-seo';`;
        } else if (plugin === 'nested-docs') {
          return `import nestedDocs from '@payloadcms/plugin-nested-docs';`;
        } else {
          return `import ${plugin} from '@payloadcms/plugin-${plugin}';`;
        }
      }).join('\n')
    : '';

  // Generate plugins initialization code
  const pluginsInitCode = plugins.length > 0
    ? `\n  plugins: [
    ${plugins.map((plugin: string) => {
      if (plugin === 'form-builder') {
        return `formBuilder({
      formOverrides: {
        admin: {
          group: 'Content',
        },
      },
      formSubmissionOverrides: {
        admin: {
          group: 'Content',
        },
      },
      redirectRelationships: ['pages'],
    }),`;
      } else if (plugin === 'seo') {
        return `seoPlugin(),`;
      } else if (plugin === 'nested-docs') {
        return `nestedDocs({
      collections: ['pages'],
    }),`;
      } else {
        return `${plugin}(),`;
      }
    }).join('\n    ')}
  ],`
    : '';

  // Generate admin code
  const adminInitCode = Object.keys(admin).length > 0
    ? `\n  admin: {
    user: '${admin.user || 'users'}',
    bundler: ${admin.bundler === 'vite' ? 'viteBundler()' : 'webpackBundler()'},
    meta: {
      titleSuffix: '- Payload CMS',
      favicon: '/assets/favicon.ico',
      ogImage: '/assets/og-image.jpg',
    },
  },`
    : '';

  // Generate database code
  const dbCode = db === 'postgres'
    ? `\n  db: postgresAdapter({
    pool: {
      connectionString: process.env.DATABASE_URI,
    },
  }),`
    : `\n  db: mongooseAdapter({
    url: process.env.MONGODB_URI,
  }),`;

  // Generate collections and globals initialization
  const collectionsInitCode = collections.length > 0
    ? `\n  collections: [
    ${collections.map((collection: string) => `${collection.charAt(0).toUpperCase() + collection.slice(1)},`).join('\n    ')}
  ],`
    : '';

  const globalsInitCode = globals.length > 0
    ? `\n  globals: [
    ${globals.map((global: string) => `${global.charAt(0).toUpperCase() + global.slice(1)},`).join('\n    ')}
  ],`
    : '';

  // Generate imports for database adapters
  const dbImports = db === 'postgres'
    ? `import { postgresAdapter } from '@payloadcms/db-postgres';`
    : `import { mongooseAdapter } from '@payloadcms/db-mongoose';`;

  // Generate bundler imports
  const bundlerImports = admin.bundler === 'vite'
    ? `import { viteBundler } from '@payloadcms/bundler-vite';`
    : `import { webpackBundler } from '@payloadcms/bundler-webpack';`;

  return `import path from 'path';
import { buildConfig } from 'payload/config';
${dbImports}
${bundlerImports}
${collectionsCode ? `\n${collectionsCode}` : ''}
${globalsCode ? `\n${globalsCode}` : ''}
${pluginsCode ? `\n${pluginsCode}` : ''}

export default buildConfig({
  serverURL: '${serverURL}',${adminInitCode}${dbCode}${pluginsInitCode}${collectionsInitCode}${globalsInitCode}
  typescript: {
    outputFile: path.resolve(__dirname, 'payload-types.ts'),
  },
  graphQL: {
    schemaOutputFile: path.resolve(__dirname, 'generated-schema.graphql'),
  },
  cors: ['http://localhost:3000'],
  csrf: [
    'http://localhost:3000',
  ],
});`;
}

/**
 * Generate an access control template for Payload CMS 3
 * @param options Access control options
 * @returns The generated access control code
 */
function generateAccessControlTemplate(options: Record<string, any>): string {
  const {
    type = 'collection',
    name = 'default',
    roles = ['admin', 'editor', 'user'],
  } = options;

  return `import { Access } from 'payload/types';

// Define user roles type
type Role = ${roles.map(role => `'${role}'`).join(' | ')};

// Access control for ${type} ${name}
export const ${name}Access: Access = ({ req }) => {
  // If there's no user, deny access
  if (!req.user) {
    return false;
  }

  // Admin users can do anything
  if (req.user.role === 'admin') {
    return true;
  }

  // Editor users can read and update but not delete
  if (req.user.role === 'editor') {
    return {
      read: true,
      update: true,
      create: true,
      delete: false,
    };
  }

  // Regular users can only read their own documents
  if (req.user.role === 'user') {
    return {
      read: {
        and: [
          {
            createdBy: {
              equals: req.user.id,
            },
          },
        ],
      },
      update: {
        createdBy: {
          equals: req.user.id,
        },
      },
      create: true,
      delete: {
        createdBy: {
          equals: req.user.id,
        },
      },
    };
  }

  // Default deny
  return false;
};`;
}

/**
 * Generate a hook template for Payload CMS 3
 * @param options Hook options
 * @returns The generated hook code
 */
function generateHookTemplate(options: Record<string, any>): string {
  const {
    type = 'collection',
    name = 'default',
    operation = 'create',
    timing = 'before',
  } = options;

  return `import { ${timing === 'before' ? 'BeforeOperation' : 'AfterOperation'} } from 'payload/types';

// ${timing}${operation.charAt(0).toUpperCase() + operation.slice(1)} hook for ${type} ${name}
export const ${timing}${operation.charAt(0).toUpperCase() + operation.slice(1)}Hook: ${timing === 'before' ? 'BeforeOperation' : 'AfterOperation'} = async ({ 
  req, 
  data, 
  operation,
  ${timing === 'after' ? 'doc,' : ''}
  ${timing === 'after' ? 'previousDoc,' : ''}
}) => {
  // Your hook logic here
  console.log(\`${timing} ${operation} operation on ${type} ${name}\`);
  
  ${timing === 'before' 
    ? `// You can modify the data before it's saved
  return data;` 
    : `// You can perform actions after the operation
  return doc;`}
};`;
}

/**
 * Generate an endpoint template for Payload CMS 3
 * @param options Endpoint options
 * @returns The generated endpoint code
 */
function generateEndpointTemplate(options: Record<string, any>): string {
  const {
    path = '/api/custom',
    method = 'get',
    auth = true,
  } = options;

  return `import { Payload } from 'payload';
import { Request, Response } from 'express';

// Custom endpoint handler
export const ${method}${path.replace(/\//g, '_').replace(/^_/, '').replace(/_$/, '')} = async (req: Request, res: Response, payload: Payload) => {
  try {
    ${auth ? `// Check if user is authenticated
    if (!req.user) {
      return res.status(401).json({
        message: 'Unauthorized',
      });
    }` : ''}

    // Your endpoint logic here
    const result = {
      message: 'Success',
      timestamp: new Date().toISOString(),
    };

    // Return successful response
    return res.status(200).json(result);
  } catch (error) {
    // Handle errors
    console.error(\`Error in ${path} endpoint:\`, error);
    return res.status(500).json({
      message: 'Internal Server Error',
      error: error.message,
    });
  }
};

// Endpoint configuration
export default {
  path: '${path}',
  method: '${method}',
  handler: ${method}${path.replace(/\//g, '_').replace(/^_/, '').replace(/_$/, '')},
};`;
}

/**
 * Generate a plugin template for Payload CMS 3
 * @param options Plugin options
 * @returns The generated plugin code
 */
function generatePluginTemplate(options: Record<string, any>): string {
  const {
    name = 'custom-plugin',
    collections = [],
    globals = [],
    fields = [],
    endpoints = [],
  } = options;

  return `import { Config, Plugin } from 'payload/config';

// Define the plugin options type
export interface ${name.replace(/-/g, '_').charAt(0).toUpperCase() + name.replace(/-/g, '_').slice(1)}PluginOptions {
  // Add your plugin options here
  enabled?: boolean;
}

// Define the plugin
export const ${name.replace(/-/g, '_')}Plugin = (options: ${name.replace(/-/g, '_').charAt(0).toUpperCase() + name.replace(/-/g, '_').slice(1)}PluginOptions = {}): Plugin => {
  return {
    // Plugin name
    name: '${name}',
    
    // Plugin configuration function
    config: (incomingConfig: Config): Config => {
      // Default options
      const { enabled = true } = options;
      
      if (!enabled) {
        return incomingConfig;
      }
      
      // Create a new config to modify
      const config = { ...incomingConfig };
      
      // Add collections
      ${collections.length > 0 ? `
      // Add plugin collections
      const collections = [
        // Define your collections here
        ${collections.map((collection: string) => `{
          slug: '${collection}',
          // Add collection configuration
        }`).join(',\n        ')}
      ];
      
      config.collections = [
        ...(config.collections || []),
        ...collections,
      ];` : '// No collections to add'}
      
      // Add globals
      ${globals.length > 0 ? `
      // Add plugin globals
      const globals = [
        // Define your globals here
        ${globals.map((global: string) => `{
          slug: '${global}',
          // Add global configuration
        }`).join(',\n        ')}
      ];
      
      config.globals = [
        ...(config.globals || []),
        ...globals,
      ];` : '// No globals to add'}
      
      // Add endpoints
      ${endpoints.length > 0 ? `
      // Add plugin endpoints
      const endpoints = [
        // Define your endpoints here
        ${endpoints.map((endpoint: string) => `{
          path: '/${endpoint}',
          method: 'get',
          handler: async (req, res) => {
            res.status(200).json({ message: '${endpoint} endpoint' });
          },
        }`).join(',\n        ')}
      ];
      
      config.endpoints = [
        ...(config.endpoints || []),
        ...endpoints,
      ];` : '// No endpoints to add'}
      
      // Return the modified config
      return config;
    },
  };
};

export default ${name.replace(/-/g, '_')}Plugin;`;
}

/**
 * Generate a block template for Payload CMS 3
 * @param options Block options
 * @returns The generated block code
 */
function generateBlockTemplate(options: Record<string, any>): string {
  const {
    name = 'custom-block',
    fields = [],
    imageField = true,
    contentField = true,
  } = options;

  // Generate fields code
  const fieldsCode = fields.length > 0
    ? fields.map((field: any) => {
        return generateFieldTemplate(field);
      }).join(',\n    ')
    : '';

  // Generate image field
  const imageFieldCode = imageField
    ? `{
    name: 'image',
    type: 'upload',
    relationTo: 'media',
    required: true,
    admin: {
      description: 'Add an image to this block',
    },
  },`
    : '';

  // Generate content field
  const contentFieldCode = contentField
    ? `{
    name: 'content',
    type: 'richText',
    required: true,
    admin: {
      description: 'Add content to this block',
    },
  },`
    : '';

  return `import { Block } from 'payload/types';

// Define the ${name} block
export const ${name.replace(/-/g, '_')}Block: Block = {
  slug: '${name}',
  labels: {
    singular: '${name.charAt(0).toUpperCase() + name.slice(1).replace(/-/g, ' ')}',
    plural: '${name.charAt(0).toUpperCase() + name.slice(1).replace(/-/g, ' ')}s',
  },
  fields: [
    ${imageFieldCode}
    ${contentFieldCode}
    ${fieldsCode}
  ],
};

export default ${name.replace(/-/g, '_')}Block;`;
}

/**
 * Generate a migration template for Payload CMS 3
 * @param options Migration options
 * @returns The generated migration code
 */
function generateMigrationTemplate(options: Record<string, any>): string {
  const {
    name = 'custom-migration',
    collection = '',
    operation = 'update',
  } = options;

  return `import { Payload } from 'payload';

// Migration: ${name}
export const ${name.replace(/-/g, '_')}Migration = async (payload: Payload) => {
  try {
    console.log('Starting migration: ${name}');
    
    ${collection ? `// Get the collection
    const collection = '${collection}';
    
    // Find documents to migrate
    const docs = await payload.find({
      collection,
      limit: 100,
    });
    
    console.log(\`Found \${docs.docs.length} documents to migrate\`);
    
    // Process each document
    for (const doc of docs.docs) {
      ${operation === 'update' ? `// Update the document
      await payload.update({
        collection,
        id: doc.id,
        data: {
          // Add your migration changes here
          migratedAt: new Date().toISOString(),
        },
      });` : operation === 'delete' ? `// Delete the document
      await payload.delete({
        collection,
        id: doc.id,
      });` : `// Custom operation
      // Add your custom migration logic here`}
    }` : `// Add your migration logic here
    // This could be schema changes, data transformations, etc.`}
    
    console.log('Migration completed successfully: ${name}');
    return { success: true };
  } catch (error) {
    console.error('Migration failed:', error);
    return { success: false, error: error.message };
  }
};

export default ${name.replace(/-/g, '_')}Migration;`;
}