sourceafButter::Butter.fan

** 'Butter' instances route HTTP requests through a stack of middleware.    
mixin Butter {
    
    ** A const value representing HTTP 1.0
    static const Version http10 := Version("1.0")

    ** A const value representing HTTP 1.1
    static const Version http11 := Version("1.1")


    ** Makes a request and returns the response.
    abstract ButterResponse sendRequest(ButterRequest req)  
    
    ** Returns an instance of the given middleware type as used by the 
    abstract ButterMiddleware? findMiddleware(Type middlewareType, Bool checked := true)

    ** Returns an read only list of middleware instances used by this 'Butter' 
    abstract ButterMiddleware[] middleware()

    ** Builds a pack of butter from the given middleware stack.
    ** The ordering of the stack *is* important.
    static Butter churnOut(ButterMiddleware[] middleware := defaultStack) {
        return ButterChain(middleware)
    }

    ** The default middleware stack. It currently returns new instances of (in order):
    **  - `StickyCookiesMiddleware`
    **  - `StickyHeadersMiddleware`
    **  - `FollowRedriectsMiddleware`
    **  - `ErrOn5xxMiddleware`
    **  - `HttpTerminator`
    static ButterMiddleware[] defaultStack() {
        ButterMiddleware[
            StickyCookiesMiddleware(),
            StickyHeadersMiddleware(),
            FollowRedirectsMiddleware(),
            ErrOn5xxMiddleware(),
            HttpTerminator()
        ]
    }

    ** Makes a simple HTTP get request to the given URI and returns the response.
    virtual ButterResponse get(Uri uri) {
        sendRequest(ButterRequest(uri))
    }

    ** Make a post request to the URI with the given form data.
    ** The 'Content-Type' is set to 'application/x-www-form-urlencoded'.
    virtual ButterResponse postForm(Uri uri, Str:Str form) {
        req := ButterRequest(uri) {
            it.method   = "POST"
        }
        req.headers.contentType = MimeType("application/x-www-form-urlencoded")
        req.body.print(Uri.encodeQuery(form))
        return sendRequest(req)
    }
    
    ** Make a post request to the URI with the given String.
    ** The 'Content-Type' is set to 'text/plain'.
    virtual ButterResponse postStr(Uri uri, Str content, Charset charset := Charset.utf8) {
        req := ButterRequest(uri) {
            it.method   = "POST"
        }
        req.headers.contentType = MimeType("text/plain")
        Buf() { it.charset = charset }.print(content).flip.in.pipe(req.body.out)
        return sendRequest(req)
    }

    ** Make a post request to the URI with the given file.
    ** The 'Content-Type' is set from the file extension's MIME type, or 'application/octet-stream' if unknown.
    virtual ButterResponse postFile(Uri uri, File file) {
        req := ButterRequest(uri) {
            it.method   = "POST"
        }
        req.headers.contentType = file.mimeType ?: MimeType("application/octet-stream")
        file.in.pipe(req.body.out, file.size, true)
        return sendRequest(req)
    }   

    override Obj? trap(Str name, Obj?[]? args := null) {
        middleware.find |mw->Bool| {
            if (mw.typeof.name.equalsIgnoreCase(name))
                return true
            if (mw.typeof.name.lower.endsWith("middleware"))
                if (mw.typeof.name[0..<-"middleware".size].equalsIgnoreCase(name))
                    return true
            return false
        } ?: throw ButterErr(ErrMsgs.chainMiddlewareNotFound(name), middleware.map { it.typeof.name })
    }
}