import { z } from 'zod';
import { parseSpec } from '../lib/parser.js';
import { formatEndpoints } from '../utils/format.js';
import type { EndpointInfo, EndpointFilter, ParameterInfo, ResponseInfo } from '../lib/types.js';
import type { OpenAPIV3 } from 'openapi-types';

export const queryToolName = 'query-endpoints';

export const queryToolDescription = 'Search and filter API endpoints in an OpenAPI spec. Filter by method, path pattern, tag, or operation ID.';

export const queryToolSchema = {
  path: z.string().describe('Path to the OpenAPI/Swagger spec file'),
  method: z.string().optional().describe('Filter by HTTP method (GET, POST, etc.)'),
  pathPattern: z.string().optional().describe('Regex pattern to match path'),
  tag: z.string().optional().describe('Filter by tag name'),
  operationId: z.string().optional().describe('Filter by exact operation ID'),
};

const HTTP_METHODS = ['get', 'post', 'put', 'patch', 'delete', 'head', 'options', 'trace'] as const;

export async function queryToolHandler(args: {
  path: string;
  method?: string;
  pathPattern?: string;
  tag?: string;
  operationId?: string;
}): Promise<{
  content: Array<{ type: 'text'; text: string }>;
  structuredContent: Record<string, unknown>;
}> {
  try {
    const { spec } = await parseSpec(args.path);

    const filter: EndpointFilter = {
      method: args.method?.toLowerCase(),
      pathPattern: args.pathPattern,
      tag: args.tag,
      operationId: args.operationId,
    };

    const endpoints = extractEndpoints(spec, filter);
    const text = formatEndpoints(endpoints);

    return {
      content: [{ type: 'text', text }],
      structuredContent: {
        success: true,
        count: endpoints.length,
        endpoints,
      },
    };
  } catch (err) {
    const error = err as Error;
    return {
      content: [{ type: 'text', text: `Error querying endpoints: ${error.message}` }],
      structuredContent: {
        success: false,
        error: error.message,
      },
    };
  }
}

function extractEndpoints(spec: object, filter: EndpointFilter): EndpointInfo[] {
  const endpoints: EndpointInfo[] = [];
  const paths = (spec as { paths?: Record<string, object> }).paths || {};

  for (const [pathName, pathItem] of Object.entries(paths)) {
    if (!pathItem) continue;

    for (const method of HTTP_METHODS) {
      const operation = (pathItem as Record<string, unknown>)[method] as OpenAPIV3.OperationObject | undefined;
      if (!operation) continue;

      // Apply filters
      if (filter.method && method !== filter.method) continue;

      if (filter.pathPattern) {
        try {
          const regex = new RegExp(filter.pathPattern);
          if (!regex.test(pathName)) continue;
        } catch {
          // Invalid regex, skip filter
        }
      }

      if (filter.tag && (!operation.tags || !operation.tags.includes(filter.tag))) continue;

      if (filter.operationId && operation.operationId !== filter.operationId) continue;

      // Extract endpoint info
      const endpoint: EndpointInfo = {
        method,
        path: pathName,
        operationId: operation.operationId,
        summary: operation.summary,
        description: operation.description,
        tags: operation.tags || [],
        parameters: extractParameters(operation, pathItem as OpenAPIV3.PathItemObject),
        requestBody: extractRequestBody(operation),
        responses: extractResponses(operation),
      };

      endpoints.push(endpoint);
    }
  }

  return endpoints;
}

function extractParameters(
  operation: OpenAPIV3.OperationObject,
  pathItem: OpenAPIV3.PathItemObject
): ParameterInfo[] {
  const params: ParameterInfo[] = [];

  // Combine path-level and operation-level parameters
  const allParams = [
    ...(pathItem.parameters || []),
    ...(operation.parameters || []),
  ] as OpenAPIV3.ParameterObject[];

  for (const param of allParams) {
    if ('$ref' in param) continue; // Skip refs (should be dereferenced)

    params.push({
      name: param.name,
      in: param.in as 'query' | 'header' | 'path' | 'cookie',
      required: param.required || false,
      description: param.description,
      schema: param.schema as object | undefined,
    });
  }

  return params;
}

function extractRequestBody(operation: OpenAPIV3.OperationObject): EndpointInfo['requestBody'] {
  if (!operation.requestBody) return undefined;

  const body = operation.requestBody as OpenAPIV3.RequestBodyObject;
  if ('$ref' in body) return undefined; // Skip refs

  return {
    required: body.required || false,
    description: body.description,
    contentTypes: Object.keys(body.content || {}),
  };
}

function extractResponses(operation: OpenAPIV3.OperationObject): ResponseInfo[] {
  const responses: ResponseInfo[] = [];

  if (!operation.responses) return responses;

  for (const [statusCode, response] of Object.entries(operation.responses)) {
    const resp = response as OpenAPIV3.ResponseObject;
    if ('$ref' in resp) continue; // Skip refs

    responses.push({
      statusCode,
      description: resp.description,
      contentTypes: Object.keys(resp.content || {}),
    });
  }

  return responses;
}