sourceafButter::ErrOn5xxMiddleware.fan

** (Middleware) - Throws `BadStatusErr` when a HTTP response returns a 4xx status code. 
** This indicates a bad request.
class ErrOn4xxMiddleware : ButterMiddleware {
    
    ** If set to 'true', this middleware throws a `BadStatusErr` on a 4xx status code. 
    ** Defaults to 'true'.
    Bool enabled    := true

    @NoDoc
    override ButterResponse sendRequest(Butter butter, ButterRequest req) {
        res := butter.sendRequest(req)
        if (enabled && (400..<500).contains(res.statusCode)) {
            body := (Str?) null
            try body = res.body.str; catch { /* wotever */ }
            throw BadStatusErr(req.method, req.url, res.statusCode, res.statusMsg, body)
        }
        return res
    }
}

** (Middleware) - Throws `BadStatusErr` when a HTTP response returns a 5xx status code.
** This indicates a server error.
class ErrOn5xxMiddleware : ButterMiddleware {
    
    ** If set to 'true', this middleware throws a `BadStatusErr` on a 5xx status code. 
    ** Defaults to 'true'.
    Bool enabled    := true

    @NoDoc
    override ButterResponse sendRequest(Butter butter, ButterRequest req) {
        res := butter.sendRequest(req)
        if (enabled && (500..<600).contains(res.statusCode)) {
            errMsg   := res.headers["X-afBedSheet-errMsg"]
            errType  := res.headers["X-afBedSheet-errType"]
            errStack := res.headers["X-afBedSheet-errStackTrace"]
            
            body := (Str?) null
            try body = res.body.str; catch { /* wotever */ }
            
            if (errMsg != null && errType != null && errStack != null)
                throw BadStatusErr(req.method, req.url, res.statusCode, errMsg, "${errType} - ${errMsg}\n${errStack}")
            throw BadStatusErr(req.method, req.url, res.statusCode, res.statusMsg, body)
        }
        return res
    }
}

** Throw by 'ErrOnXxxMiddleware' when a HTTP response returns a bad status code.
** 
** To prevent 'BadStatusErrs' from being thrown, just disable the relevant middleware.
** For example, to prevent a 'BadStatusErr' from being thrown when a 404 is returned:
** 
**   syntax: fantom
**   butterDish.errOn4xxx.enabled = false
** 
** To prevent a 'BadStatusErr' from being thrown when a 500 is returned:
** 
**   syntax: fantom
**   butterDish.errOn5xxx.enabled = false 
const class BadStatusErr : Err {
        
    ** The failing HTTP request URL
    const Uri reqUrl
    
    ** The failing HTTP request Method
    const Str reqMethod
    
    ** The failing HTTP response status code
    const Int statusCode
    
    ** The failing HTTP response status message
    const Str statusMsg

    ** The body of the failing HTTP response (if a string)
    const Str? body

    ** Create a 'BadStatusErr'.
    new make(Str reqMethod, Uri reqUrl, Int statusCode, Str statusMsg, Str? body := null, Err? cause := null) : super(mess(reqMethod, reqUrl, statusCode, statusMsg), cause) {
        this.reqMethod  = reqMethod
        this.reqUrl     = reqUrl
        this.statusCode = statusCode
        this.statusMsg  = statusMsg
        this.body       = body
    }
    
    ** Pre-pends the list of available values to the stack trace.
    override Str toStr() {
        buf := StrBuf()
        buf.add("${typeof.qname}: ${mess(reqMethod, reqUrl, statusCode, statusMsg)}\n")
        if (body != null) {
            buf.add("\nBody:\n")
            body.splitLines.each { buf.add("  $it\n")}
        }
        buf.add("\nStack Trace:")
        return buf.toStr
    }

    private static Str mess(Str reqMethod, Uri reqUrl, Int statusCode, Str statusMsg) {
        "${statusCode} - ${statusMsg} at ${reqMethod} `${reqUrl}`"
    }
}