handler.go

// Copyright 2019 xgfone
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package ship

import (
	"net/http"
	"strings"
)

// Handler is a handler of the HTTP request.
type Handler func(*Context) error

// HTTPHandler converts itself to http.Handler.
func (h Handler) HTTPHandler(s *Ship) http.Handler {
	return ToHTTPHandler(s, h)
}

type httpHandlerBridge struct {
	ship *Ship
	Handler
}

func newHTTPHandlerBridge(s *Ship, h Handler) httpHandlerBridge {
	if h == nil {
		panic("Handler must not be nil")
	} else if s == nil {
		panic("Ship must not be nil")
	}
	return httpHandlerBridge{ship: s, Handler: h}
}

func (h httpHandlerBridge) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	ctx := h.ship.AcquireContext(r, w)
	h.Handler(ctx)
	h.ship.ReleaseContext(ctx)
}

// ToHTTPHandler converts the Handler to http.Handler
func ToHTTPHandler(s *Ship, h Handler) http.Handler {
	return newHTTPHandlerBridge(s, h)
}

// FromHTTPHandler converts http.Handler to Handler.
func FromHTTPHandler(h http.Handler) Handler {
	return func(ctx *Context) error {
		h.ServeHTTP(ctx.res, ctx.req)
		return nil
	}
}

// FromHTTPHandlerFunc converts http.HandlerFunc to Handler.
func FromHTTPHandlerFunc(h http.HandlerFunc) Handler {
	return FromHTTPHandler(h)
}

// NothingHandler returns a Handler doing nothing.
func NothingHandler() Handler { return func(*Context) error { return nil } }

// OkHandler returns a Handler only sending the response "200 OK"
func OkHandler() Handler {
	return func(c *Context) error { return c.Text(http.StatusOK, "OK") }
}

// NotFoundHandler returns a NotFound handler.
func NotFoundHandler() Handler {
	return func(c *Context) error {
		return c.Text(http.StatusNotFound, "Not Found")
	}
}

// MethodNotAllowedHandler returns a MethodNotAllowed handler.
func MethodNotAllowedHandler(allowedMethods []string) Handler {
	return func(c *Context) error {
		c.SetRespHeader(HeaderAllow, strings.Join(allowedMethods, ", "))
		return c.NoContent(http.StatusMethodNotAllowed)
	}
}