1 files changed, 99 insertions, 0 deletions
diff --git a/internal/fetcher/channel.go b/internal/fetcher/channel.go
new file mode 100644
index 0000000..cadbab2
--- /dev/null
+++ b/internal/fetcher/channel.go
@@ -0,0 +1,99 @@
+package fetcher
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"os"
+	"os/exec"
+	"path"
+	"searchix/internal/config"
+	"searchix/internal/file"
+	"strconv"
+	"strings"
+
+	"github.com/pkg/errors"
+)
+
+type ChannelFetcher struct {
+	DataPath   string
+	Source     *config.Source
+	SourceFile string
+	Logger     *slog.Logger
+}
+
+func (i *ChannelFetcher) FetchIfNeeded(
+	parent context.Context,
+) (f FetchedFiles, updated bool, err error) {
+	ctx, cancel := context.WithTimeout(parent, i.Source.FetchTimeout)
+	defer cancel()
+
+	dest := i.DataPath
+
+	var before string
+	before, err = os.Readlink(dest)
+	if file.NeedNotExist(err) != nil {
+		err = errors.WithMessagef(err, "could not call readlink on file %s", dest)
+
+		return
+	}
+	i.Logger.Debug("stat before", "name", before)
+
+	args := []string{
+		"--no-build-output",
+		"--timeout",
+		strconv.Itoa(int(i.Source.FetchTimeout.Seconds() - 1)),
+		fmt.Sprintf("<%s/%s>", i.Source.Channel, i.Source.ImportPath),
+		"--attr",
+		i.Source.Attribute,
+		"--out-link",
+		dest,
+	}
+
+	if i.Source.URL != "" {
+		args = append(args, "-I", fmt.Sprintf("%s=%s", i.Source.Channel, i.Source.URL))
+	}
+
+	i.Logger.Debug("nix-build command", "args", args)
+	cmd := exec.CommandContext(ctx, "nix-build", args...)
+	var out []byte
+	out, err = cmd.Output()
+	if err != nil {
+		err = errors.WithMessage(err, "failed to run nix-build (--dry-run)")
+
+		return
+	}
+	i.Logger.Debug("nix-build", "output", strings.TrimSpace(string(out)))
+
+	outPath := path.Join(dest, i.Source.OutputPath)
+	i.Logger.Debug(
+		"checking output path",
+		"outputPath",
+		outPath,
+		"dest",
+		dest,
+		"source",
+		i.Source.OutputPath,
+	)
+	var after string
+	after, err = os.Readlink(dest)
+	if err = file.NeedNotExist(err); err != nil {
+		err = errors.WithMessagef(
+			err,
+			"failed to stat output file from nix-build, filename: %s",
+			outPath,
+		)
+
+		return
+	}
+	i.Logger.Debug("stat after", "name", after)
+
+	updated = before != after
+
+	f = FetchedFiles{
+		Options:  path.Join(dest, i.Source.OutputPath, "options.json"),
+		Packages: path.Join(dest, i.Source.OutputPath, "packages.json"),
+	}
+
+	return
+}