1package identity
 2
 3import (
 4	"sync"
 5
 6	"github.com/MichaelMure/git-bug/entity"
 7	"github.com/MichaelMure/git-bug/repository"
 8)
 9
10// Resolver define the interface of an Identity resolver, able to load
11// an identity from, for example, a repo or a cache.
12type Resolver interface {
13	ResolveIdentity(id entity.Id) (Interface, error)
14}
15
16// SimpleResolver is a Resolver loading Identities directly from a Repo
17type SimpleResolver struct {
18	repo repository.Repo
19}
20
21func NewSimpleResolver(repo repository.Repo) *SimpleResolver {
22	return &SimpleResolver{repo: repo}
23}
24
25func (r *SimpleResolver) ResolveIdentity(id entity.Id) (Interface, error) {
26	return ReadLocal(r.repo, id)
27}
28
29// StubResolver is a Resolver that doesn't load anything, only returning IdentityStub instances
30type StubResolver struct{}
31
32func NewStubResolver() *StubResolver {
33	return &StubResolver{}
34}
35
36func (s *StubResolver) ResolveIdentity(id entity.Id) (Interface, error) {
37	return &IdentityStub{id: id}, nil
38}
39
40// CachedResolver is a resolver ensuring that loading is done only once through another Resolver.
41type CachedResolver struct {
42	mu         sync.RWMutex
43	resolver   Resolver
44	identities map[entity.Id]Interface
45}
46
47func NewCachedResolver(resolver Resolver) *CachedResolver {
48	return &CachedResolver{
49		resolver:   resolver,
50		identities: make(map[entity.Id]Interface),
51	}
52}
53
54func (c *CachedResolver) ResolveIdentity(id entity.Id) (Interface, error) {
55	c.mu.RLock()
56	if i, ok := c.identities[id]; ok {
57		c.mu.RUnlock()
58		return i, nil
59	}
60	c.mu.RUnlock()
61
62	c.mu.Lock()
63	defer c.mu.Unlock()
64
65	i, err := c.resolver.ResolveIdentity(id)
66	if err != nil {
67		return nil, err
68	}
69	c.identities[id] = i
70	return i, nil
71}