package versions

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"strings"

	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-builder/builds"
)

// The builder's tools of its versions (design 51 *Events of the builder*, *Tools of the builder*).
const (
	VersionsTool     = "builder_versions"
	PublishAgainTool = "builder_publish_again"
	FloorAgainTool   = "builder_floor_again"
	TagTool          = "builder_tag"
	TagAsksTool      = "builder_tag_asks"
	UntagTool        = "builder_untag"
	OldFormTool      = "builder_old_form"
	// OldFormClosedEvent is, with builds.VersionNumberedEvent, the builder's own family `version`, kept seven days,
	// apart from its builds' ends, so a waiter on a build's end does not wake on them.
	OldFormClosedEvent = "version.old-form-closed"
)

// NumberedOf is the version.numbered body of an entry (builds.VersionNumbered, the contract a build module reads).
func NumberedOf(e Entry, head string) builds.VersionNumbered {
	return builds.VersionNumbered{Name: e.Name, Kind: e.Kind, Version: e.Version, Tag: e.Tag, Module: e.Module, Fingerprint: e.Fingerprint,
		Commit: e.Commit, Digest: e.Digest, Seat: e.Seat, Head: head}
}

// Reader reads the state as the tools bundle may: every key, and one.
type Reader struct {
	Keys func() ([]string, error)
	Get  func(key string) (json.RawMessage, bool, error)
}

// readStore is a Store over a Reader that refuses every write: the tools bundle only reads versions.
type readStore struct{ r Reader }

var errReadOnly = errors.New("the versions are written by the builder alone")

func (s readStore) Get(_ context.Context, key string) ([]byte, uint64, bool, error) {
	v, ok, err := s.r.Get(key)
	return v, 0, ok, err
}
func (readStore) Create(context.Context, string, []byte) (uint64, error) { return 0, errReadOnly }
func (readStore) Update(context.Context, string, []byte, uint64) (uint64, error) {
	return 0, errReadOnly
}
func (s readStore) KeysOf(_ context.Context, filter string) ([]string, error) {
	all, err := s.r.Keys()
	if err != nil {
		return nil, err
	}
	if filter == AllFilter {
		return all, nil
	}
	prefix := strings.TrimSuffix(filter, "*")
	var out []string
	for _, k := range all {
		if strings.HasPrefix(k, prefix) && !strings.Contains(k[len(prefix):], ".") {
			out = append(out, k)
		}
	}
	return out, nil
}

// VersionsAnswer is what builder_versions answers.
type VersionsAnswer struct {
	Name     string  `json:"name"`
	Versions []Entry `json:"versions"`
	// Asked, Recorded and Why answer a holder's question for one version and digest (ADR 0605 §4).
	Asked    string `json:"asked,omitempty"`
	Recorded *bool  `json:"recorded,omitempty"`
	Why      string `json:"why,omitempty"`
}

// AnswerVersions is builder_versions: a name's versions in order, in one call; with a version (and a digest), whether
// the builder numbered it with that digest, which the holder asks before it stores (ADR 0605 §4).
func AnswerVersions(ctx context.Context, r Reader, name, version, digest string) (VersionsAnswer, error) {
	name = strings.TrimSpace(name)
	if name == "" {
		return VersionsAnswer{}, errors.New("name is required: the package, image, bundle or archive name")
	}
	v := Versions{Store: readStore{r}}
	all, err := v.Of(ctx, name)
	if err != nil {
		return VersionsAnswer{}, err
	}
	out := VersionsAnswer{Name: name, Versions: all}
	if out.Versions == nil {
		out.Versions = []Entry{}
	}
	if version = strings.TrimSpace(version); version != "" {
		_, ok, why, err := v.Recorded(ctx, name, version, strings.TrimSpace(digest))
		if err != nil {
			return VersionsAnswer{}, fmt.Errorf("%s@%s: %w", name, version, err)
		}
		out.Asked, out.Recorded, out.Why = version, &ok, why
	}
	return out, nil
}

// VersionsDescription is builder_versions' description.
const VersionsDescription = "A name's versions as the builder numbered them (its state versions, design 51): every trunk and tagged " +
	"version of a package, image, bundle or archive in order, each with its kind, series, fingerprint, commit, source revision, digest, " +
	"seat, state (numbered, published, refused with its reason, removed with its time, reason and the event that removed it, or kept: its seat kept it whole on remove, its digest shared, with the reason and the other tags naming it, kept_with) and when. " +
	"With version, and digest, it also answers recorded: whether the builder numbered that version with that digest, and why not: the " +
	"question a registry seat's holder asks before it stores a publish (ADR 0605 §4). Read-only."