// Copyright 2018 Palantir Technologies, Inc.
//
// 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 baseapp

import (
	"net/http"
	"time"

	"github.com/rcrowley/go-metrics"
	"github.com/rs/zerolog"
)

const (
	// nanoTimeFormat is the same as time.RFC3339Nano, but uses a consistent
	// number of digits instead of removing trailing zeros
	nanoTimeFormat = "2006-01-02T15:04:05.000000000Z07:00"
)

// DefaultParams returns a recommended set of parameters for servers. It
// enables logging and configures logging, adds metrics, and adds default
// middleware. All component parameters are exported and can be selected
// individually if desired.
func DefaultParams(logger zerolog.Logger, metricsPrefix string) []Param {
	var registry metrics.Registry
	if metricsPrefix == "" {
		registry = metrics.NewRegistry()
	} else {
		registry = metrics.NewPrefixedRegistry(metricsPrefix)
	}

	return []Param{
		WithLogger(logger),
		WithRegistry(registry),
		WithMiddleware(DefaultMiddleware(logger, registry)...),
		WithUTCNanoTime(),
		WithErrorLogging(RichErrorMarshalFunc),
		WithMetrics(),
	}
}

// WithLogger sets a root logger used by the server.
func WithLogger(logger zerolog.Logger) Param {
	return func(b *Server) error {
		b.logger = logger
		return nil
	}
}

// WithMiddleware sets middleware that is applied to all routes handled by the
// server.
func WithMiddleware(middleware ...func(http.Handler) http.Handler) Param {
	return func(b *Server) error {
		b.middleware = middleware
		return nil
	}
}

// WithUTCNanoTime adds a UTC timestamp with nanosecond precision to log lines.
func WithUTCNanoTime() Param {
	return func(b *Server) error {
		zerolog.TimeFieldFormat = nanoTimeFormat
		zerolog.TimestampFunc = func() time.Time {
			return time.Now().UTC()
		}
		return nil
	}
}

// WithErrorLogging sets a formatting function used to log errors.
func WithErrorLogging(marshalFunc func(err error) interface{}) Param {
	return func(b *Server) error {
		zerolog.ErrorMarshalFunc = marshalFunc
		return nil
	}
}

// WithRegistry sets the metrics registry for the server.
func WithRegistry(registry metrics.Registry) Param {
	return func(b *Server) error {
		b.registry = registry
		return nil
	}
}

// WithMetrics enables server and runtime metrics collection.
func WithMetrics() Param {
	return func(s *Server) error {
		s.initFns = append(s.initFns, func(s *Server) { RegisterDefaultMetrics(s.Registry()) })
		return nil
	}
}

func WithHTTPServer(server *http.Server) Param {
	return func(s *Server) error {
		s.server = server
		return nil
	}
}