1 files changed, 113 insertions, 0 deletions
diff --git a/cache/cache.go b/cache/cache.go
new file mode 100644
index 0000000..b57d8b8
--- /dev/null
+++ b/cache/cache.go
@@ -0,0 +1,113 @@
+package cache
+
+import (
+	"bufio"
+	"errors"
+	"io"
+	"io/fs"
+	"os"
+	"path"
+	"pik/model"
+	"pik/paths"
+	"strings"
+)
+
+type Cache struct {
+	Entries []Entry
+}
+
+func (c Cache) Merge(other Cache) Cache {
+	mp := make(map[string]string)
+	for _, e := range append(c.Entries, other.Entries...) {
+		mp[e.Path] = e.Label
+	}
+	result := Cache{}
+	for p, l := range mp {
+		result.Entries = append(result.Entries, Entry{Label: l, Path: p})
+	}
+	return result
+}
+
+type Entry struct {
+	Path  string
+	Label string
+}
+
+var Path = path.Join(paths.Cache, "contexts")
+
+var UnexpectedEntryError = errors.New("unexpected cache entry")
+
+func Load() (Cache, error) {
+	fd, err := os.Open(Path)
+	if errors.Is(err, os.ErrNotExist) {
+		return Cache{}, nil
+	} else if err != nil {
+		return Cache{}, err
+	}
+	defer fd.Close()
+	return FromReader(fd)
+}
+
+func FromReader(r io.Reader) (Cache, error) {
+	c := Cache{}
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		if line == "" || line[0] == '#' || line[0:2] == "//" {
+			continue
+		}
+
+		entry := &Entry{}
+		parts := strings.SplitN(line, "#", 2)
+		switch len(parts) {
+		case 2:
+			entry.Label = strings.TrimSpace(parts[1])
+			fallthrough
+		case 1:
+			entry.Path = strings.TrimSpace(parts[0])
+		default:
+			return c, UnexpectedEntryError
+		}
+		c.Entries = append(c.Entries, *entry)
+	}
+	return c, nil
+}
+
+func (c Cache) String() string {
+	b := strings.Builder{}
+	for _, e := range c.Entries {
+		b.WriteString(e.Path)
+		b.WriteString(" # ")
+		b.WriteString(e.Label)
+		b.WriteString("\n")
+	}
+	return b.String()
+}
+
+func New(st *model.State) Cache {
+	c := &Cache{}
+	for _, s := range st.Sources {
+		c.Entries = append(c.Entries, Entry{
+			Path:  s.Path,
+			Label: s.Label(),
+		})
+	}
+	return *c
+}
+
+func Save(s *model.State) error {
+	ld, err := Load()
+	if err != nil {
+		return err
+	}
+	c := New(s).Merge(ld)
+	return os.WriteFile(Path, []byte(c.String()), os.ModePerm)
+}
+
+func LoadState(f fs.FS, cache Cache, indexers []model.Indexer, runners []model.Runner) (*model.State, error) {
+	var locs []string
+	for _, e := range cache.Entries {
+		locs = append(locs, e.Path)
+	}
+	return model.NewState(f, locs, indexers, runners)
+}