import { Controller, Delete, Get, Post, Req, Res } from "@nestjs/common";
import { ApiOperation, ApiResponse, ApiTags } from "@nestjs/swagger";
import type { Request, Response } from "express";
import { McpService } from "./mcp.service";

@ApiTags("mcp")
@Controller("mcp")
export class McpController {
  constructor(private readonly mcpService: McpService) {}

  @Post()
  @ApiOperation({
    summary: "Send JSON-RPC message",
    description:
      "Accepts a JSON-RPC request, notification, or response. " +
      "Returns either `application/json` for a single response or " +
      "`text/event-stream` (SSE) when the server streams multiple messages.",
  })
  @ApiResponse({
    status: 200,
    description: "JSON-RPC response (application/json or text/event-stream)",
  })
  @ApiResponse({
    status: 202,
    description: "Accepted — input was a notification or response only",
  })
  @ApiResponse({
    status: 400,
    description: "Bad Request — malformed JSON-RPC payload",
  })
  post(@Req() req: Request, @Res() res: Response): Promise<void> {
    return this.mcpService.handle(req, res);
  }

  @Get()
  @ApiOperation({
    summary: "Open server-sent event stream",
    description:
      "Opens a persistent SSE stream so the server can push JSON-RPC requests and " +
      "notifications to the client without a prior POST. " +
      "Requires `Accept: text/event-stream`. Pass `Last-Event-ID` to resume a broken stream.",
  })
  @ApiResponse({ status: 200, description: "SSE stream (text/event-stream)" })
  @ApiResponse({
    status: 405,
    description: "Method Not Allowed — server does not offer an SSE stream",
  })
  get(@Req() req: Request, @Res() res: Response): Promise<void> {
    return this.mcpService.handle(req, res);
  }

  @Delete()
  @ApiOperation({
    summary: "Terminate session",
    description:
      "Explicitly terminates a session identified by the `Mcp-Session-Id` header. " +
      "The server may return 405 if it does not support client-initiated session termination.",
  })
  @ApiResponse({ status: 200, description: "Session terminated" })
  @ApiResponse({ status: 404, description: "Session not found" })
  @ApiResponse({
    status: 405,
    description:
      "Method Not Allowed — server does not support session termination",
  })
  delete(@Req() req: Request, @Res() res: Response): Promise<void> {
    return this.mcpService.handle(req, res);
  }
}