tree-wide: use a standard project layout

Keep main.go files under cmd/ and internal libraries under internal/.
This will allow us to add more exutables under cmd/ (whereas only one
was possible when main.go was kept in the root).

Signed-off-by: Tom Gundersen <teg@jklm.no>

internal/rpmmd/repository.go

@@ -0,0 +1,90 @@
+package rpmmd
+
+import (
+	"encoding/json"
+	"os/exec"
+	"sort"
+	"time"
+)
+
+type RepoConfig struct {
+	Id         string `json:"id"`
+	Name       string `json:"name"`
+	BaseURL    string `json:"baseurl,omitempty"`
+	Metalink   string `json:"metalink,omitempty"`
+	MirrorList string `json:"mirrorlist,omitempty"`
+}
+
+type PackageList []Package
+
+type Package struct {
+	Name        string
+	Summary     string
+	Description string
+	URL         string
+	Epoch       uint
+	Version     string
+	Release     string
+	Arch        string
+	BuildTime   time.Time
+	License     string
+}
+
+type PackageSpec struct {
+	Name    string `json:"name"`
+	Epoch   uint   `json:"epoch,omitempty"`
+	Version string `json:"version,omitempty"`
+	Release string `json:"release,omitempty"`
+	Arch    string `json:"arch,omitempty"`
+}
+
+func runDNF(command string, arguments []string, result interface{}) error {
+	argv := append([]string{"dnf-json", command}, arguments...)
+
+	cmd := exec.Command("python3", argv...)
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		return err
+	}
+
+	err = cmd.Start()
+	if err != nil {
+		return err
+	}
+
+	err = json.NewDecoder(stdout).Decode(result)
+	if err != nil {
+		return err
+	}
+
+	return cmd.Wait()
+}
+
+func FetchPackageList(repo RepoConfig) (PackageList, error) {
+	var packages PackageList
+	err := runDNF("dump", nil, &packages)
+	return packages, err
+}
+
+func Depsolve(specs ...string) ([]PackageSpec, error) {
+	var dependencies []PackageSpec
+	err := runDNF("depsolve", specs, &dependencies)
+	return dependencies, err
+}
+
+func (packages PackageList) Search(name string) (int, int) {
+	first := sort.Search(len(packages), func(i int) bool {
+		return packages[i].Name >= name
+	})
+
+	if first == len(packages) || packages[first].Name != name {
+		return first, 0
+	}
+
+	last := first + 1
+	for last < len(packages) && packages[last].Name == name {
+		last++
+	}
+
+	return first, last - first
+}