package com.billpaymentservice.bbps.exception;

import java.util.*;
import java.util.stream.Collectors;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.*;
import org.springframework.validation.FieldError;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.annotation.*;

import com.billpaymentservice.bbps.dto.ResponseModel;

@ControllerAdvice
public class GlobalExceptionHandler {

    private static final Logger logger = LoggerFactory.getLogger(GlobalExceptionHandler.class);
    
   
    @ExceptionHandler(MethodArgumentNotValidException.class)
    public ResponseEntity<ResponseModel<?>> handleValidation(MethodArgumentNotValidException ex) {
        List<Map<String, String>> fieldErrors = ex.getBindingResult().getFieldErrors()
            .stream()
            .map(fe -> Map.of("field", fe.getField(), "message", fe.getDefaultMessage()))
            .collect(Collectors.toList());

        logger.warn("Validation failed: {}", fieldErrors);
        ResponseModel<List<Map<String, String>>> resp = new ResponseModel<>(
            "Validation failed for request",
            "FAILED",
            HttpStatus.BAD_REQUEST.value(),
            null
        );
        // put validation errors into data or duplicate field in ResponseModel as required
        resp.setData(fieldErrors);
        return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(resp);
    }

    @ExceptionHandler(AppException.class)
    public ResponseEntity<ResponseModel<?>> handleAppException(AppException ex) {
        logger.warn("AppException: status={}, message={}", ex.getStatus(), ex.getMessage());
        ResponseModel<?> resp = new ResponseModel<>(ex.getMessage(), ex.getStatus(), ex.getStatusCode(), ex.getData());
        return ResponseEntity.status(HttpStatus.valueOf(ex.getStatusCode())).body(resp);
    }
    
    @ExceptionHandler(CustomException.class)
    public ResponseEntity<ResponseModel<?>> handleCustomException(CustomException ex) {
        logger.warn("CustomException: {}", ex.getMessage());
        ResponseModel<?> resp = new ResponseModel<>(
            ex.getMessage(),
            "FAILED",
            HttpStatus.BAD_REQUEST.value(),
            null
        );
        return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(resp);
    }


    @ExceptionHandler(Exception.class)
    public ResponseEntity<ResponseModel<?>> handleAll(Exception ex) {
        logger.error("Unhandled exception", ex);
        ResponseModel<?> response = new ResponseModel<>(
            "Service temporarily unavailable. Please try again later.",
            "FAILED",
            HttpStatus.INTERNAL_SERVER_ERROR.value(),
            null
        );
        return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(response);
    }
}