solher/zest

package zest

import (
    "errors"
    "log"
    "net/http"
    "os"
    "runtime"
)

// Recovery is a Negroni inspired middleware handler that recovers from any panic
// and writes a 500 UNDEFINED_ERROR Zest API error.
type Recovery struct {
    Logger    *log.Logger
    Render    *Render
    StackAll  bool
    StackSize int
}

// NewRecovery returns a new instance of Recovery
func NewRecovery() *Recovery {
    return &Recovery{
        Logger:    log.New(os.Stdout, "", 0),
        Render:    NewRender(),
        StackAll:  false,
        StackSize: 1024 * 8,
    }
}

func (rec *Recovery) ServeHTTP(w http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
    defer func() {
        if err := recover(); err != nil {
            stack := make([]byte, rec.StackSize)
            stack = stack[:runtime.Stack(stack, rec.StackAll)]

            f := "PANIC: %s\n%s"
            if rec.Logger != nil {
                rec.Logger.Printf(f, err, stack)
            }

            err := &APIError{Description: "An internal error occured. Please retry later.", ErrorCode: "UNDEFINED_ERROR"}

            rec.Render.JSONError(w, http.StatusInternalServerError, err, errors.New("undefined error"))
        }
    }()

    next(w, r)
}