Add reconciliation state foundation

internal/state/outputs.go

@@ -0,0 +1,82 @@
+package state
+
+import (
+	"fmt"
+	"time"
+)
+
+type OutputProjection struct {
+	Path       string
+	Kind       string
+	SourcePath string
+	Transform  string
+	URL        string
+	SHA256     string
+	Size       int64
+}
+
+func FindOutputByPath(outputs []OutputFile, path string) (OutputFile, bool) {
+	for _, output := range outputs {
+		if output.Path == path {
+			return output, true
+		}
+	}
+	return OutputFile{}, false
+}
+
+func MergeOutputFiles(retained, planned []OutputFile) ([]OutputFile, error) {
+	outputs := make([]OutputFile, 0, len(retained)+len(planned))
+	indexByPath := make(map[string]int, len(retained)+len(planned))
+	for _, output := range retained {
+		if _, exists := indexByPath[output.Path]; exists {
+			return nil, fmt.Errorf("state output path %q is duplicated", output.Path)
+		}
+		indexByPath[output.Path] = len(outputs)
+		outputs = append(outputs, output)
+	}
+	seenPlanned := make(map[string]struct{}, len(planned))
+	for _, output := range planned {
+		if _, exists := seenPlanned[output.Path]; exists {
+			return nil, fmt.Errorf("state output path %q is duplicated", output.Path)
+		}
+		seenPlanned[output.Path] = struct{}{}
+		if index, exists := indexByPath[output.Path]; exists {
+			outputs[index] = output
+			continue
+		}
+		indexByPath[output.Path] = len(outputs)
+		outputs = append(outputs, output)
+	}
+	return outputs, nil
+}
+
+func ManagedOutputPaths(s DistributorState) []string {
+	paths := make([]string, 0, len(s.Outputs))
+	for _, output := range s.Outputs {
+		paths = append(paths, output.Path)
+	}
+	return paths
+}
+
+func ProjectOutputs(outputs []OutputProjection, existing []OutputFile, now time.Time) []OutputFile {
+	now = now.UTC()
+	files := make([]OutputFile, 0, len(outputs))
+	for _, output := range outputs {
+		createdAt := now
+		if existingOutput, ok := FindOutputByPath(existing, output.Path); ok {
+			createdAt = existingOutput.CreatedAt
+		}
+		files = append(files, OutputFile{
+			Path:       output.Path,
+			Kind:       output.Kind,
+			SourcePath: output.SourcePath,
+			Transform:  output.Transform,
+			URL:        output.URL,
+			SHA256:     output.SHA256,
+			Size:       output.Size,
+			CreatedAt:  createdAt,
+			UpdatedAt:  now,
+		})
+	}
+	return files
+}