// Package mdb contains a number of database wrappers for databases I commonly
// use
package mdb

import (
	"github.com/mediocregopher/mediocre-go-lib/mcfg"
	"github.com/mediocregopher/mediocre-go-lib/mctx"
	"github.com/mediocregopher/mediocre-go-lib/mlog"
	"github.com/mediocregopher/mediocre-go-lib/mrun"
	"google.golang.org/api/option"
)

// GCE wraps configuration parameters commonly used for interacting with GCE
// services.
type GCE struct {
	Project  string
	CredFile string
}

// MGCE returns a GCE instance which will be initialized and configured when the
// start event is triggered on ctx (see mrun.Start). defaultProject is used as
// the default value for the mcfg parameter this function creates.
func MGCE(ctx mctx.Context, defaultProject string) *GCE {
	ctx = mctx.ChildOf(ctx, "gce")
	credFile := mcfg.String(ctx, "cred-file", "", "Path to GCE credientials JSON file, if any")

	var project *string
	const projectUsage = "Name of GCE project to use"
	if defaultProject == "" {
		project = mcfg.RequiredString(ctx, "project", projectUsage)
	} else {
		project = mcfg.String(ctx, "project", defaultProject, projectUsage)
	}

	var gce GCE
	mrun.OnStart(ctx, func(mctx.Context) error {
		gce.Project = *project
		gce.CredFile = *credFile
		return nil
	})
	return &gce
}

// ClientOptions generates and returns the ClientOption instances which can be
// passed into most GCE client drivers.
func (gce *GCE) ClientOptions() []option.ClientOption {
	var opts []option.ClientOption
	if gce.CredFile != "" {
		opts = append(opts, option.WithCredentialsFile(gce.CredFile))
	}
	return opts
}

// KV implements the mlog.KVer interface.
func (gce *GCE) KV() map[string]interface{} {
	return mlog.KV{
		"gceProject": gce.Project,
	}
}