package delivery

import (
	"encoding/json"
	"fmt"
)

// The builder's event version.numbered (design 51 *Events of the builder*, *The floor*): said once per version the builder
// numbers, on its own family `version` (seven days), apart from its builds' ends, so a waiter on a build's end does not
// wake on it. A build module consumes it to publish a build's version with the held digest, which stores nothing.
const (
	// VersionNumberedEvent is the event's local name.
	VersionNumberedEvent = "version.numbered"
	// VersionNumberedSubject is its subject, as a consumer's filter names it.
	VersionNumberedSubject = "mesh.mod." + BuilderModule + ".event." + VersionNumberedEvent
)

// VersionNumbered is the body of VersionNumberedEvent: a numbered version of a name, the build it was numbered for, and
// what the build module needs to publish it.
type VersionNumbered struct {
	// Name is the numbered name, as builder_versions lists it; Kind its artifact's kind.
	Name    string `json:"name"`
	Kind    string `json:"kind"`
	Version string `json:"version"`
	Tag     string `json:"tag,omitempty"`
	// Module and Fingerprint are the build the version was numbered for; Commit its source commit.
	Module      string `json:"module"`
	Fingerprint string `json:"fingerprint"`
	Commit      string `json:"commit,omitempty"`
	// Digest is the built artifact's, when the build held one; Seat the registry seat it is published through.
	Digest string `json:"digest,omitempty"`
	Seat   string `json:"seat,omitempty"`
	// Head is the head the version answers, when it answers a tag ask.
	Head string `json:"head,omitempty"`
	// Again is when builder_publish_again said it once more, so the bus's dedup does not drop it.
	Again string `json:"again,omitempty"`
}

// EncodeVersionNumbered writes the body, refusing one that names no name, version, module or fingerprint.
func EncodeVersionNumbered(n VersionNumbered) ([]byte, error) {
	if n.Name == "" || n.Version == "" || n.Module == "" || n.Fingerprint == "" {
		return nil, fmt.Errorf("delivery: %s names its name, version, module and fingerprint", VersionNumberedEvent)
	}
	return json.Marshal(n)
}

// DecodeVersionNumbered reads the body, with the same refusal.
func DecodeVersionNumbered(data []byte) (VersionNumbered, error) {
	var n VersionNumbered
	if err := json.Unmarshal(data, &n); err != nil {
		return VersionNumbered{}, fmt.Errorf("delivery: %s is not readable: %w", VersionNumberedEvent, err)
	}
	if _, err := EncodeVersionNumbered(n); err != nil {
		return VersionNumbered{}, err
	}
	return n, nil
}