// Copyright 2014 The Cockroach Authors.
//
// 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.
//
// Author: Tobias Schottdorf

package log

import (
	"fmt"
	"io"
	"net/http"
	"strings"

	"golang.org/x/net/context"
)

const httpLogLevelPrefix = "/debug/vmodule/"

func handleVModule(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
	spec := r.RequestURI[len(httpLogLevelPrefix):]
	if err := logging.vmodule.Set(spec); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
	}
	Infof(context.Background(), "vmodule changed to: %s", spec)
	fmt.Fprint(w, "ok: "+spec)
}

func init() {
	http.Handle(httpLogLevelPrefix, http.HandlerFunc(handleVModule))
	copyStandardLogTo("INFO")
}

// FatalOnPanic recovers from a panic and exits the process with a
// Fatal log. This is useful for avoiding a panic being caught through
// a CGo exported function or preventing HTTP handlers from recovering
// panics and ignoring them.
func FatalOnPanic() {
	if r := recover(); r != nil {
		Fatalf(context.Background(), "unexpected panic: %s", r)
	}
}

// SetExitFunc allows setting a function that will be called to exit the
// process when a Fatal message is generated.
func SetExitFunc(f func(int)) {
	logging.mu.Lock()
	defer logging.mu.Unlock()
	logging.exitFunc = f
}

// logDepth uses the PrintWith to format the output string and
// formulate the context information into the machine-readable
// dictionary for separate binary-log output.
func logDepth(ctx context.Context, depth int, sev Severity, format string, args []interface{}) {
	// TODO(tschottdorf): logging hooks should have their entry point here.
	addStructured(ctx, sev, depth+1, format, args)
}

// Shout logs to the specified severity's log, and also to the real
// stderr if logging is currently redirected to a file.
func Shout(ctx context.Context, sev Severity, args ...interface{}) {
	logDepth(ctx, 1, sev, "", args)
	if stderrRedirected {
		fmt.Fprintf(OrigStderr, "*\n* %s: %s\n*\n", sev.String(),
			strings.Replace(MakeMessage(ctx, "", args), "\n", "\n* ", -1))
	}
}

// Infof logs to the INFO log.
// It extracts log tags from the context and logs them along with the given
// message. Arguments are handled in the manner of fmt.Printf; a newline is
// appended.
func Infof(ctx context.Context, format string, args ...interface{}) {
	logDepth(ctx, 1, Severity_INFO, format, args)
}

// Info logs to the INFO log.
// It extracts log tags from the context and logs them along with the given
// message. Arguments are handled in the manner of fmt.Print; a newline is
// appended.
func Info(ctx context.Context, args ...interface{}) {
	logDepth(ctx, 1, Severity_INFO, "", args)
}

// InfofDepth logs to the INFO log, offsetting the caller's stack frame by
// 'depth'.
// It extracts log tags from the context and logs them along with the given
// message. Arguments are handled in the manner of fmt.Printf; a newline is
// appended.
func InfofDepth(ctx context.Context, depth int, format string, args ...interface{}) {
	logDepth(ctx, depth+1, Severity_INFO, format, args)
}

// Warningf logs to the WARNING and INFO logs.
// It extracts log tags from the context and logs them along with the given
// message. Arguments are handled in the manner of fmt.Printf; a newline is
// appended.
func Warningf(ctx context.Context, format string, args ...interface{}) {
	logDepth(ctx, 1, Severity_WARNING, format, args)
}

// Warning logs to the WARNING and INFO logs.
// It extracts log tags from the context and logs them along with the given
// message. Arguments are handled in the manner of fmt.Print; a newline is
// appended.
func Warning(ctx context.Context, args ...interface{}) {
	logDepth(ctx, 1, Severity_WARNING, "", args)
}

// WarningfDepth logs to the WARNING and INFO logs, offsetting the caller's
// stack frame by 'depth'.
// It extracts log tags from the context and logs them along with the given
// message. Arguments are handled in the manner of fmt.Printf; a newline is
// appended.
func WarningfDepth(ctx context.Context, depth int, format string, args ...interface{}) {
	logDepth(ctx, depth+1, Severity_WARNING, format, args)
}

// Errorf logs to the ERROR, WARNING, and INFO logs.
// It extracts log tags from the context and logs them along with the given
// message. Arguments are handled in the manner of fmt.Printf; a newline is
// appended.
func Errorf(ctx context.Context, format string, args ...interface{}) {
	logDepth(ctx, 1, Severity_ERROR, format, args)
}

// Error logs to the ERROR, WARNING, and INFO logs.
// It extracts log tags from the context and logs them along with the given
// message. Arguments are handled in the manner of fmt.Print; a newline is
// appended.
func Error(ctx context.Context, args ...interface{}) {
	logDepth(ctx, 1, Severity_ERROR, "", args)
}

// ErrorfDepth logs to the ERROR, WARNING, and INFO logs, offsetting the
// caller's stack frame by 'depth'.
// It extracts log tags from the context and logs them along with the given
// message. Arguments are handled in the manner of fmt.Printf; a newline is
// appended.
func ErrorfDepth(ctx context.Context, depth int, format string, args ...interface{}) {
	logDepth(ctx, depth+1, Severity_ERROR, format, args)
}

// Fatalf logs to the INFO, WARNING, ERROR, and FATAL logs, including a stack
// trace of all running goroutines, then calls os.Exit(255).
// It extracts log tags from the context and logs them along with the given
// message. Arguments are handled in the manner of fmt.Printf; a newline is
// appended.
func Fatalf(ctx context.Context, format string, args ...interface{}) {
	logDepth(ctx, 1, Severity_FATAL, format, args)
}

// Fatal logs to the INFO, WARNING, ERROR, and FATAL logs, including a stack
// trace of all running goroutines, then calls os.Exit(255).
// It extracts log tags from the context and logs them along with the given
// message. Arguments are handled in the manner of fmt.Print; a newline is
// appended.
func Fatal(ctx context.Context, args ...interface{}) {
	logDepth(ctx, 1, Severity_FATAL, "", args)
}

// FatalfDepth logs to the INFO, WARNING, ERROR, and FATAL logs (offsetting the
// caller's stack frame by 'depth'), including a stack trace of all running
// goroutines, then calls os.Exit(255).
// It extracts log tags from the context and logs them along with the given
// message. Arguments are handled in the manner of fmt.Printf; a newline is
// appended.
func FatalfDepth(ctx context.Context, depth int, format string, args ...interface{}) {
	logDepth(ctx, depth+1, Severity_FATAL, format, args)
}

// V returns true if the logging verbosity is set to the specified level or
// higher.
func V(level level) bool {
	return VDepth(level, 1)
}

// Format writes the log entry to the specified writer.
func (e Entry) Format(w io.Writer) error {
	buf := formatLogEntry(e, nil, nil)
	defer logging.putBuffer(buf)
	_, err := w.Write(buf.Bytes())
	return err
}