Refactor fetch and pacman packages into subpackages

Split fetch into alpm and aur subpackages for better organization.
Rename state to log. Split pacman into read and sync subpackages.
Remove validation in favor of read.DBFreshness.

pkg/pacman/read/read.go

@@ -0,0 +1,109 @@
+package read
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+	"time"
+
+	"github.com/Riyyi/declpac/pkg/fetch"
+	"github.com/Riyyi/declpac/pkg/output"
+)
+
+var LockFile = "/var/lib/pacman/db.lock"
+
+func List() ([]string, error) {
+	start := time.Now()
+	fmt.Fprintf(os.Stderr, "[debug] List: starting...\n")
+
+	cmd := exec.Command("pacman", "-Qq")
+	output, err := cmd.Output()
+	if err != nil {
+		return nil, err
+	}
+
+	list := strings.Split(strings.TrimSpace(string(output)), "\n")
+	if list[0] == "" {
+		list = nil
+	}
+
+	fmt.Fprintf(os.Stderr, "[debug] List: done (%.2fs)\n", time.Since(start).Seconds())
+	return list, nil
+}
+
+func ListOrphans() ([]string, error) {
+	start := time.Now()
+	fmt.Fprintf(os.Stderr, "[debug] ListOrphans: starting...\n")
+
+	cmd := exec.Command("pacman", "-Qdtq")
+	output, err := cmd.Output()
+	if err != nil {
+		return nil, err
+	}
+
+	orphans := strings.Split(strings.TrimSpace(string(output)), "\n")
+	if len(orphans) > 0 && orphans[0] == "" {
+		orphans = orphans[1:]
+	}
+
+	fmt.Fprintf(os.Stderr, "[debug] ListOrphans: done (%.2fs)\n", time.Since(start).Seconds())
+	return orphans, nil
+}
+
+func DBFreshness() (bool, error) {
+	info, err := os.Stat(LockFile)
+	if err != nil {
+		return false, nil
+	}
+
+	age := time.Since(info.ModTime())
+	return age <= 24*time.Hour, nil
+}
+
+func DryRun(packages []string) (*output.Result, error) {
+	start := time.Now()
+	fmt.Fprintf(os.Stderr, "[debug] DryRun: starting...\n")
+
+	f, err := fetch.New()
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	fmt.Fprintf(os.Stderr, "[debug] DryRun: initialized fetcher (%.2fs)\n", time.Since(start).Seconds())
+
+	resolved, err := f.Resolve(packages)
+	if err != nil {
+		return nil, err
+	}
+	fmt.Fprintf(os.Stderr, "[debug] DryRun: packages resolved (%.2fs)\n", time.Since(start).Seconds())
+
+	var toInstall []string
+	var aurPkgs []string
+	for _, pkg := range packages {
+		info := resolved[pkg]
+		if info == nil || (!info.Exists && !info.InAUR) {
+			return nil, fmt.Errorf("package not found: %s", pkg)
+		}
+		if info.InAUR {
+			aurPkgs = append(aurPkgs, pkg)
+		} else if !info.Installed {
+			toInstall = append(toInstall, pkg)
+		}
+	}
+	fmt.Fprintf(os.Stderr, "[debug] DryRun: packages categorized (%.2fs)\n", time.Since(start).Seconds())
+
+	orphans, err := ListOrphans()
+	if err != nil {
+		return nil, err
+	}
+	fmt.Fprintf(os.Stderr, "[debug] DryRun: orphans listed (%.2fs)\n", time.Since(start).Seconds())
+
+	fmt.Fprintf(os.Stderr, "[debug] DryRun: done (%.2fs)\n", time.Since(start).Seconds())
+	return &output.Result{
+		Installed: len(toInstall) + len(aurPkgs),
+		Removed:   len(orphans),
+		ToInstall: append(toInstall, aurPkgs...),
+		ToRemove:  orphans,
+	}, nil
+}