package catalogue

import "encoding/json"

// The sources mesh-config says a resolved value came from, in mesh-config_resolved (novox/hq ADR 0348 §9): a key of
// it holds {"value": …, "source": …}.
const (
	SourceMesh    = "mesh"
	SourceNode    = "node"
	SourceModule  = "module"
	SourceDefault = "default"
	SourceUnset   = "unset"
)

// LaidSource says whether a value resolved from source is laid over a module's files: mesh config, node config and the
// module's own value are; a manifest's default is not, since it is the composition's already and a taken key is laid
// only when a layer sets it, never from a default (TakesSettingsField); an unset value is not, since a required one is
// refused by the composition by name. **The one rule for every composer** (issue 1126, C2): the controller's config
// read and a node composing its own lay the same values, so the two compose the same files.
func LaidSource(source string) bool {
	switch source {
	case SourceMesh, SourceNode, SourceModule:
		return true
	}
	return false
}

// LaidValue is one key of mesh-config_resolved read as a composer lays it: its value, and true when its source is laid
// (LaidSource) and it holds a value; false for a default, an unset value, a source not known and a value that cannot be
// read.
func LaidValue(raw []byte) (any, bool) {
	var r struct {
		Value  json.RawMessage `json:"value"`
		Source string          `json:"source"`
	}
	if json.Unmarshal(raw, &r) != nil || !LaidSource(r.Source) || len(r.Value) == 0 {
		return nil, false
	}
	var v any
	if json.Unmarshal(r.Value, &v) != nil {
		return nil, false
	}
	return v, true
}