default_context.go

package buffalo

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"reflect"
	"sort"
	"strings"
	"sync"
	"time"

	"github.com/gobuffalo/buffalo/binding"
	"github.com/gobuffalo/buffalo/render"
)

// assert that DefaultContext is implementing Context
var _ Context = &DefaultContext{}
var _ context.Context = &DefaultContext{}

// TODO(sio4): #road-to-v1 - make DefaultContext private
// and only allow it to be generated by App.newContext() or any similar.

// DefaultContext is, as its name implies, a default
// implementation of the Context interface.
type DefaultContext struct {
	context.Context
	response    http.ResponseWriter
	request     *http.Request
	params      url.Values
	logger      Logger
	session     *Session
	contentType string
	data        *sync.Map
	flash       *Flash
}

// Response returns the original Response for the request.
func (d *DefaultContext) Response() http.ResponseWriter {
	return d.response
}

// Request returns the original Request.
func (d *DefaultContext) Request() *http.Request {
	return d.request
}

// Params returns all of the parameters for the request,
// including both named params and query string parameters.
func (d *DefaultContext) Params() ParamValues {
	return d.params
}

// Logger returns the Logger for this context.
func (d *DefaultContext) Logger() Logger {
	return d.logger
}

// Param returns a param, either named or query string,
// based on the key.
func (d *DefaultContext) Param(key string) string {
	return d.Params().Get(key)
}

// Set a value onto the Context. Any value set onto the Context
// will be automatically available in templates.
func (d *DefaultContext) Set(key string, value interface{}) {
	if d.data == nil {
		d.data = &sync.Map{}
	}
	d.data.Store(key, value)
}

// Value that has previously stored on the context.
func (d *DefaultContext) Value(key interface{}) interface{} {
	if k, ok := key.(string); ok && d.data != nil {
		if v, ok := d.data.Load(k); ok {
			return v
		}
	}
	if d.Context == nil {
		return nil
	}
	return d.Context.Value(key)
}

// Session for the associated Request.
func (d *DefaultContext) Session() *Session {
	return d.session
}

// Cookies for the associated request and response.
func (d *DefaultContext) Cookies() *Cookies {
	return &Cookies{d.request, d.response}
}

// Flash messages for the associated Request.
func (d *DefaultContext) Flash() *Flash {
	return d.flash
}

type paginable interface {
	Paginate() string
}

// Render a status code and render.Renderer to the associated Response.
// The request parameters will be made available to the render.Renderer
// "{{.params}}". Any values set onto the Context will also automatically
// be made available to the render.Renderer. To render "no content" pass
// in a nil render.Renderer.
func (d *DefaultContext) Render(status int, rr render.Renderer) error {
	start := time.Now()
	defer func() {
		d.LogField("render", time.Since(start))
	}()

	if rr == nil {
		d.Response().WriteHeader(status)
		return nil
	}

	data := d.Data()
	pp := map[string]string{}
	for k, v := range d.params {
		pp[k] = v[0]
	}
	data["params"] = pp
	data["flash"] = d.Flash().data
	data["session"] = d.Session()
	data["request"] = d.Request()
	data["status"] = status
	bb := &bytes.Buffer{}

	err := rr.Render(bb, data)
	if err != nil {
		var er render.ErrRedirect
		if errors.As(err, &er) {
			return d.Redirect(er.Status, er.URL)
		}
		return HTTPError{Status: http.StatusInternalServerError, Cause: err}
	}

	if d.Session() != nil {
		d.Flash().Clear()
		d.Flash().persist(d.Session())
		if err := d.Session().Save(); err != nil {
			return HTTPError{Status: http.StatusInternalServerError, Cause: err}
		}
	}

	d.Response().Header().Set("Content-Type", rr.ContentType())
	if p, ok := data["pagination"].(paginable); ok {
		d.Response().Header().Set("X-Pagination", p.Paginate())
	}
	d.Response().WriteHeader(status)
	_, err = io.Copy(d.Response(), bb)
	if err != nil {
		return HTTPError{Status: http.StatusInternalServerError, Cause: err}
	}

	return nil
}

// Bind the interface to the request.Body. The type of binding
// is dependent on the "Content-Type" for the request. If the type
// is "application/json" it will use "json.NewDecoder". If the type
// is "application/xml" it will use "xml.NewDecoder". See the
// github.com/gobuffalo/buffalo/binding package for more details.
func (d *DefaultContext) Bind(value interface{}) error {
	return binding.Exec(d.Request(), value)
}

// LogField adds the key/value pair onto the Logger to be printed out
// as part of the request logging. This allows you to easily add things
// like metrics (think DB times) to your request.
func (d *DefaultContext) LogField(key string, value interface{}) {
	if d.logger == nil {
		return
	}
	d.logger = d.logger.WithField(key, value)
}

// LogFields adds the key/value pairs onto the Logger to be printed out
// as part of the request logging. This allows you to easily add things
// like metrics (think DB times) to your request.
func (d *DefaultContext) LogFields(values map[string]interface{}) {
	if d.logger == nil {
		return
	}
	d.logger = d.logger.WithFields(values)
}

func (d *DefaultContext) Error(status int, err error) error {
	return HTTPError{Status: status, Cause: err}
}

var mapType = reflect.ValueOf(map[string]interface{}{}).Type()

// Redirect a request with the given status to the given URL.
func (d *DefaultContext) Redirect(status int, url string, args ...interface{}) error {
	if d.Session() != nil {
		d.Flash().persist(d.Session())
		if err := d.Session().Save(); err != nil {
			return HTTPError{Status: http.StatusInternalServerError, Cause: err}
		}
	}

	if strings.HasSuffix(url, "Path()") {
		if len(args) > 1 {
			return fmt.Errorf("you must pass only a map[string]interface{} to a route path: %T", args)
		}
		var m map[string]interface{}
		if len(args) == 1 {
			rv := reflect.Indirect(reflect.ValueOf(args[0]))
			if !rv.Type().ConvertibleTo(mapType) {
				return fmt.Errorf("you must pass only a map[string]interface{} to a route path: %T", args)
			}
			m = rv.Convert(mapType).Interface().(map[string]interface{})
		}
		h, ok := d.Value(strings.TrimSuffix(url, "()")).(RouteHelperFunc)
		if !ok {
			return fmt.Errorf("could not find a route helper named %s", url)
		}
		url, err := h(m)
		if err != nil {
			return err
		}
		http.Redirect(d.Response(), d.Request(), string(url), status)
		return nil
	}

	if len(args) > 0 {
		url = fmt.Sprintf(url, args...)
	}
	http.Redirect(d.Response(), d.Request(), url, status)
	return nil
}

// Data contains all the values set through Get/Set.
func (d *DefaultContext) Data() map[string]interface{} {
	m := map[string]interface{}{}

	if d.data == nil {
		return m
	}

	d.data.Range(func(k, v interface{}) bool {
		s, ok := k.(string)
		if !ok {
			return false
		}
		m[s] = v
		return true
	})
	return m
}

func (d *DefaultContext) String() string {
	data := d.Data()
	bb := make([]string, 0, len(data))

	for k, v := range data {
		if _, ok := v.(RouteHelperFunc); !ok {
			bb = append(bb, fmt.Sprintf("%s: %s", k, v))
		}
	}
	sort.Strings(bb)
	return strings.Join(bb, "\n\n")
}

// File returns an uploaded file by name, or an error
func (d *DefaultContext) File(name string) (binding.File, error) {
	req := d.Request()
	if err := req.ParseMultipartForm(5 * 1024 * 1024); err != nil {
		return binding.File{}, err
	}
	f, h, err := req.FormFile(name)
	bf := binding.File{
		File:       f,
		FileHeader: h,
	}
	return bf, err
}

// MarshalJSON implements json marshaling for the context
func (d *DefaultContext) MarshalJSON() ([]byte, error) {
	m := map[string]interface{}{}
	data := d.Data()
	for k, v := range data {
		// don't try and marshal ourself
		if _, ok := v.(*DefaultContext); ok {
			continue
		}
		if _, err := json.Marshal(v); err == nil {
			// it can be marshaled, so add it:
			m[k] = v
		}
	}
	return json.Marshal(m)
}