/**
 * TouchBistro MCP Server - Server Class with Lazy Tool Loading
 */

import { Server } from '@modelcontextprotocol/sdk/server/index.js';
import {
  CallToolRequestSchema,
  ListToolsRequestSchema,
} from '@modelcontextprotocol/sdk/types.js';
import { z } from 'zod';
import type { TouchBistroApiClient } from './lib/api-client.js';

// Type definition for tool modules
interface ToolDefinition {
  description: string;
  parameters: z.ZodTypeAny;
  handler: (args: any, client: TouchBistroApiClient) => Promise<any>;
}

type ToolModule = Record<string, ToolDefinition>;

export class TouchBistroMCPServer {
  private server: Server;
  private client: TouchBistroApiClient;
  private toolModules: Map<string, () => Promise<ToolModule>>;
  private allToolDefinitions: Record<string, ToolDefinition> = {};

  constructor(client: TouchBistroApiClient) {
    this.client = client;
    this.toolModules = new Map();

    this.server = new Server(
      {
        name: 'touchbistro-mcp-server',
        version: '1.0.0',
      },
      {
        capabilities: {
          tools: {},
        },
      }
    );

    this.setupToolModules();
    this.setupHandlers();
  }

  /**
   * Register tool modules for lazy loading
   */
  private setupToolModules(): void {
    this.toolModules.set('orders', async () => {
      const module = await import('./tools/orders.js');
      return module.orderTools;
    });

    this.toolModules.set('menu', async () => {
      const module = await import('./tools/menu.js');
      return module.menuTools;
    });

    this.toolModules.set('tables', async () => {
      const module = await import('./tools/tables.js');
      return module.tableTools;
    });

    this.toolModules.set('staff', async () => {
      const module = await import('./tools/staff.js');
      return module.staffTools;
    });

    this.toolModules.set('customers', async () => {
      const module = await import('./tools/customers.js');
      return module.customerTools;
    });

    this.toolModules.set('reservations', async () => {
      const module = await import('./tools/reservations.js');
      return module.reservationTools;
    });

    this.toolModules.set('inventory', async () => {
      const module = await import('./tools/inventory.js');
      return module.inventoryTools;
    });

    this.toolModules.set('payments', async () => {
      const module = await import('./tools/payments.js');
      return module.paymentTools;
    });
  }

  /**
   * Load all tools from registered modules
   */
  private async loadAllTools(): Promise<void> {
    const toolModules = await Promise.all(
      Array.from(this.toolModules.values()).map(loader => loader())
    );

    for (const toolModule of toolModules) {
      Object.assign(this.allToolDefinitions, toolModule);
    }

    console.error(`Loaded ${Object.keys(this.allToolDefinitions).length} TouchBistro tools`);
  }

  /**
   * Convert Zod schema to JSON Schema for MCP
   */
  private zodToJsonSchema(schema: z.ZodTypeAny): any {
    if (schema instanceof z.ZodObject) {
      const shape = schema.shape;
      const properties: any = {};
      const required: string[] = [];

      for (const [key, value] of Object.entries(shape)) {
        properties[key] = this.zodToJsonSchema(value as z.ZodTypeAny);
        if (!(value instanceof z.ZodOptional)) {
          required.push(key);
        }
      }

      return {
        type: 'object',
        properties,
        ...(required.length > 0 ? { required } : {}),
      };
    }

    if (schema instanceof z.ZodString) {
      const base: any = { type: 'string' };
      if (schema.description) base.description = schema.description;
      return base;
    }

    if (schema instanceof z.ZodNumber) {
      const base: any = { type: 'number' };
      if (schema.description) base.description = schema.description;
      return base;
    }

    if (schema instanceof z.ZodBoolean) {
      const base: any = { type: 'boolean' };
      if (schema.description) base.description = schema.description;
      return base;
    }

    if (schema instanceof z.ZodArray) {
      return {
        type: 'array',
        items: this.zodToJsonSchema(schema.element),
        ...(schema.description ? { description: schema.description } : {}),
      };
    }

    if (schema instanceof z.ZodEnum) {
      return {
        type: 'string',
        enum: schema.options,
        ...(schema.description ? { description: schema.description } : {}),
      };
    }

    if (schema instanceof z.ZodOptional) {
      return this.zodToJsonSchema(schema.unwrap());
    }

    return { type: 'string' };
  }

  /**
   * Setup MCP protocol handlers
   */
  private setupHandlers(): void {
    // List tools handler
    this.server.setRequestHandler(ListToolsRequestSchema, async () => {
      if (Object.keys(this.allToolDefinitions).length === 0) {
        await this.loadAllTools();
      }

      const mcpTools = Object.entries(this.allToolDefinitions).map(([name, tool]) => ({
        name,
        description: tool.description,
        inputSchema: this.zodToJsonSchema(tool.parameters),
      }));

      return {
        tools: mcpTools,
      };
    });

    // Call tool handler
    this.server.setRequestHandler(CallToolRequestSchema, async (request) => {
      if (Object.keys(this.allToolDefinitions).length === 0) {
        await this.loadAllTools();
      }

      const { name, arguments: args } = request.params;
      const tool = this.allToolDefinitions[name as keyof typeof this.allToolDefinitions];

      if (!tool) {
        throw new Error(`Unknown tool: ${name}`);
      }

      try {
        const validatedArgs = tool.parameters.parse(args);
        const result = await tool.handler(validatedArgs, this.client);
        return result;
      } catch (error: any) {
        if (error instanceof z.ZodError) {
          throw new Error(`Invalid parameters: ${error.message}`);
        }
        throw new Error(`Tool execution failed: ${error.message}`);
      }
    });
  }

  /**
   * Start the server with the given transport
   */
  async start(transport: any): Promise<void> {
    await this.server.connect(transport);
  }
}