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// Copyright (c) 2016 Uber Technologies, Inc.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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package zap
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import (
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	"encoding/json"
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	"errors"
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	"fmt"
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	"io"
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	"net/http"
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	"go.uber.org/zap/zapcore"
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)
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// ServeHTTP is a simple JSON endpoint that can report on or change the current
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// logging level.
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//
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// # GET
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//
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// The GET request returns a JSON description of the current logging level like:
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//
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//	{"level":"info"}
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//
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// # PUT
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//
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// The PUT request changes the logging level. It is perfectly safe to change the
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// logging level while a program is running. Two content types are supported:
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//
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//	Content-Type: application/x-www-form-urlencoded
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//
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// With this content type, the level can be provided through the request body or
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// a query parameter. The log level is URL encoded like:
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//
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//	level=debug
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//
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// The request body takes precedence over the query parameter, if both are
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// specified.
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//
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// This content type is the default for a curl PUT request. Following are two
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// example curl requests that both set the logging level to debug.
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//
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//	curl -X PUT localhost:8080/log/level?level=debug
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//	curl -X PUT localhost:8080/log/level -d level=debug
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//
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// For any other content type, the payload is expected to be JSON encoded and
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// look like:
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//
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//	{"level":"info"}
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//
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// An example curl request could look like this:
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//
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//	curl -X PUT localhost:8080/log/level -H "Content-Type: application/json" -d '{"level":"debug"}'
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func (lvl AtomicLevel) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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	if err := lvl.serveHTTP(w, r); err != nil {
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		w.WriteHeader(http.StatusInternalServerError)
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		fmt.Fprintf(w, "internal error: %v", err)
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	}
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}
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func (lvl AtomicLevel) serveHTTP(w http.ResponseWriter, r *http.Request) error {
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	type errorResponse struct {
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		Error string `json:"error"`
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	}
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	type payload struct {
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		Level zapcore.Level `json:"level"`
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	}
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	enc := json.NewEncoder(w)
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	switch r.Method {
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	case http.MethodGet:
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		return enc.Encode(payload{Level: lvl.Level()})
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	case http.MethodPut:
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		requestedLvl, err := decodePutRequest(r.Header.Get("Content-Type"), r)
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		if err != nil {
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			w.WriteHeader(http.StatusBadRequest)
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			return enc.Encode(errorResponse{Error: err.Error()})
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		}
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		lvl.SetLevel(requestedLvl)
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		return enc.Encode(payload{Level: lvl.Level()})
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	default:
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		w.WriteHeader(http.StatusMethodNotAllowed)
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		return enc.Encode(errorResponse{
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			Error: "Only GET and PUT are supported.",
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		})
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	}
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}
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// Decodes incoming PUT requests and returns the requested logging level.
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func decodePutRequest(contentType string, r *http.Request) (zapcore.Level, error) {
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	if contentType == "application/x-www-form-urlencoded" {
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		return decodePutURL(r)
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	}
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	return decodePutJSON(r.Body)
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}
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func decodePutURL(r *http.Request) (zapcore.Level, error) {
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	lvl := r.FormValue("level")
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	if lvl == "" {
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		return 0, errors.New("must specify logging level")
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	}
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	var l zapcore.Level
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	if err := l.UnmarshalText([]byte(lvl)); err != nil {
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		return 0, err
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	}
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	return l, nil
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}
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func decodePutJSON(body io.Reader) (zapcore.Level, error) {
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	var pld struct {
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		Level *zapcore.Level `json:"level"`
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	}
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	if err := json.NewDecoder(body).Decode(&pld); err != nil {
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		return 0, fmt.Errorf("malformed request body: %v", err)
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	}
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	if pld.Level == nil {
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		return 0, errors.New("must specify logging level")
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	}
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	return *pld.Level, nil
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}
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