// Package server provides HTTP server functionality
package server

import (
	"errors"
	"fmt"
	"net/http"
)

// Common server error types
var (
	// ErrInvalidConfig indicates missing or invalid server configuration
	ErrInvalidConfig = errors.New("invalid server configuration")

	// ErrServerStartFailed indicates failure to start the server
	ErrServerStartFailed = errors.New("failed to start server")

	// ErrUnauthorizedOrigin indicates a request from an unauthorized origin
	ErrUnauthorizedOrigin = errors.New("unauthorized origin")

	// ErrRouteSetupFailed indicates failure to set up routes
	ErrRouteSetupFailed = errors.New("failed to set up routes")

	// ErrHandlerNotFound indicates a missing handler
	ErrHandlerNotFound = errors.New("handler not found")

	// ErrPanicRecovered indicates a recovered panic
	ErrPanicRecovered = errors.New("panic recovered")

	// ErrMiddlewareError indicates a middleware error
	ErrMiddlewareError = errors.New("middleware error")

	// HTTP error types
	ErrBadRequest         = errors.New("bad request")
	ErrUnauthorized       = errors.New("unauthorized")
	ErrValidationFailed   = errors.New("validation failed")
	ErrForbidden          = errors.New("forbidden")
	ErrNotFound           = errors.New("not found")
	ErrMethodNotAllowed   = errors.New("method not allowed")
	ErrInternalServer     = errors.New("internal server error")
	ErrServiceUnavailable = errors.New("service unavailable")
)

// Error represents a server-specific error with detailed context
type Error struct {
	// Op is the operation that failed (e.g., "start", "route", "middleware")
	Op string

	// Err is the underlying error
	Err error

	// Details contains additional error context
	Details string

	// StatusCode is the HTTP status code (if applicable)
	StatusCode int

	// Path is the request path (if applicable)
	Path string

	// Method is the HTTP method (if applicable)
	Method string

	// Origin is the request origin (if applicable)
	Origin string

	// RequestID is the request ID (if applicable)
	RequestID string
}

// Error returns a string representation of the error
func (e *Error) Error() string {
	msg := fmt.Sprintf("server %s failed", e.Op)
	if e.StatusCode > 0 {
		msg = fmt.Sprintf("%s with status %d", msg, e.StatusCode)
	}
	if e.Method != "" && e.Path != "" {
		msg = fmt.Sprintf("%s for %s %s", msg, e.Method, e.Path)
	}
	if e.Origin != "" {
		msg = fmt.Sprintf("%s from origin %s", msg, e.Origin)
	}
	if e.RequestID != "" {
		msg = fmt.Sprintf("%s (request ID: %s)", msg, e.RequestID)
	}
	if e.Details != "" {
		msg = fmt.Sprintf("%s: %s", msg, e.Details)
	}
	if e.Err != nil {
		msg = fmt.Sprintf("%s: %v", msg, e.Err)
	}
	return msg
}

// Unwrap returns the underlying error
func (e *Error) Unwrap() error {
	return e.Err
}

// Is reports whether target matches this error
func (e *Error) Is(target error) bool {
	return errors.Is(e.Err, target)
}

// NewError creates a new server error
func NewError(op string, err error, details string) *Error {
	return &Error{
		Op:      op,
		Err:     err,
		Details: details,
	}
}

// NewRequestError creates a new server error with request context
func NewRequestError(op string, method string, path string, statusCode int, err error, details string) *Error {
	return &Error{
		Op:         op,
		Method:     method,
		Path:       path,
		StatusCode: statusCode,
		Err:        err,
		Details:    details,
	}
}

// NewMiddlewareError creates a new middleware error
func NewMiddlewareError(op string, requestID string, err error, details string) *Error {
	return &Error{
		Op:        op,
		RequestID: requestID,
		Err:       err,
		Details:   details,
	}
}

// NewCORSError creates a new CORS error
func NewCORSError(origin string, err error, details string) *Error {
	return &Error{
		Op:      "cors",
		Origin:  origin,
		Err:     err,
		Details: details,
	}
}

// StatusCode returns the appropriate HTTP status code for the error
func StatusCode(err error) int {
	var e *Error
	if errors.As(err, &e) && e.StatusCode > 0 {
		return e.StatusCode
	}

	switch {
	case errors.Is(err, ErrBadRequest):
		return http.StatusBadRequest
	case errors.Is(err, ErrUnauthorized):
		return http.StatusUnauthorized
	case errors.Is(err, ErrForbidden):
		return http.StatusForbidden
	case errors.Is(err, ErrNotFound):
		return http.StatusNotFound
	case errors.Is(err, ErrMethodNotAllowed):
		return http.StatusMethodNotAllowed
	case errors.Is(err, ErrUnauthorizedOrigin):
		return http.StatusForbidden
	case errors.Is(err, ErrServiceUnavailable):
		return http.StatusServiceUnavailable
	default:
		return http.StatusInternalServerError
	}
}

// IsClientError returns true if the error represents a client error (4xx)
func IsClientError(err error) bool {
	code := StatusCode(err)
	return code >= 400 && code < 500
}

// IsServerError returns true if the error represents a server error (5xx)
func IsServerError(err error) bool {
	code := StatusCode(err)
	return code >= 500
}