// Copyright 2018 The LUCI 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.

package config

import (
	"strings"
)

// Set is a name of a configuration set: a bunch of config files versioned and
// stored as a single unit in a same repository.
//
// A config set name consists of a domain and a series of path components:
// domain/target[/ref].
//
//  - Service config sets are config sets in the "services" domain, with the
//    service name as the target.
//  - Project config sets are config sets in the "projects" domain. The target
//    is the project name.
type Set string

// ServiceSet returns the name of a config set for the specified service.
func ServiceSet(service string) Set { return Set("services/" + service) }

// ProjectSet returns the config set for the specified project.
func ProjectSet(project string) Set { return RefSet(project, "") }

// RefSet returns the config set for the specified project and ref. If ref
// is empty, this will equal the ProjectSet value.
func RefSet(project string, ref string) Set {
	if ref == "" {
		return Set("projects/" + project)
	}
	return Set(strings.Join([]string{"projects", project, ref}, "/"))
}

// Split splits a Set into its domain, target, and ref components.
func (cs Set) Split() (domain, target, ref string) {
	switch p := strings.SplitN(string(cs), "/", 3); len(p) {
	case 1:
		return p[0], "", ""
	case 2:
		return p[0], p[1], ""
	default:
		return p[0], p[1], p[2]
	}
}

// Service returns a service name for a service-rooted config set or empty
// string for all other sets.
func (cs Set) Service() string {
	domain, target, _ := cs.Split()
	if domain == "services" {
		return target
	}
	return ""
}

// Project returns a project name for a project-rooted config set or empty
// string for all other sets.
//
// Use ProjectAndRef if you need to get both the project name and the ref.
func (cs Set) Project() string {
	domain, target, _ := cs.Split()
	if domain == "projects" {
		return target
	}
	return ""
}

// Ref returns a ref component of a project-rooted config set or empty string
// for all other sets.
//
// Use ProjectAndRef if you need to get both the project name and the ref.
func (cs Set) Ref() string {
	domain, _, ref := cs.Split()
	if domain == "projects" {
		return ref
	}
	return ""
}

// ProjectAndRef splits a project-rooted config set (projects/<name>[/...]) into
// its project name and ref components.
//
// For example, "projects/foo/bar/baz" is a config set that belongs to project
// "foo". It will be parsed into ("foo", "bar/baz").
//
// If configSet is not a project config set, empty strings will be returned.
func (cs Set) ProjectAndRef() (project, ref string) {
	domain, project, ref := cs.Split()
	if domain == "projects" {
		return
	}
	return "", ""
}