// Package mapping is md <-> Gitea JSON. The whole translation, and only the
// translation.
//
// Pure functions: no network, no filesystem, no flags, no clock. Give it a
// payload and it hands back a domain issue; give it an issue and it hands back
// a request body. That purity is the point — it can be reasoned about and
// tested without a Gitea anywhere, and it is the one package to open when the
// two representations disagree.
//
// Direction of knowledge: this package imports the domain and the protocol
// (internal/wire), and nothing imports it but the command layer. The domain
// never imports it, and TestDomainDependsOnNothing over in internal/issue fails
// the moment it does; the transport never imports it either, and
// TestTransportDoesNotImportTheDomain over in internal/gitea says so. Both
// sides speak wire's shapes, which is what lets the two meet without either one
// reaching into the other.
//
// What crosses the boundary, and what does not:
//
//	domain          Gitea             note
//	----------------------------------------------------------------------
//	id (slug)       body marker       <!-- kettle:id … -->, first line of the
//	                                  tracker-side body; stripped out of the
//	                                  local copy — see marker.go
//	title           title             verbatim, both ways
//	body            body              verbatim up, verbatim down except the
//	                                  marker and checkbox state
//	state           state             open/closed, the same vocabulary
//	labels          labels[]          names both ways; ids only on write
//	assignees       assignees[]       logins
//	milestone       milestone.title   resolved to an id on write
//	depends         —                 slugs; #N is translated at this edge
//	—               number, html_url  lands in Extra as gitea:/url:
//	—               ref               Extra as branch:; push fills it from git
//
// `depends:` is the authoritative graph and is always slugs. The body's
// `## Depends on` section is human prose and is passed through UNCHANGED in
// both directions: a pull seeds `depends:` from the `#N` it finds there, and a
// push never rewrites what the author wrote. Deliberate — a translator that
// edits prose churns the body on every round trip.
//
// The ONE thing this package adds to a body is the id marker, and it does so
// because the slug has to survive a push: push deletes the local file, so the
// tracker has to be the thing that remembers what the issue was called here.
package mapping

import (
	"git.noodles.cam/claude-skills/marketplace/cli/internal/issue"
	"git.noodles.cam/claude-skills/marketplace/cli/internal/wire"
)

// Origin is what this bridge writes into the domain's `origin:` field. The
// domain records that an issue exists somewhere else; only this layer knows
// where, and what the handle beside it means.
const Origin = "gitea"

// The sync-owned metadata fields, named once. Every one of them is bookkeeping
// about a tracker, which is why the domain carries them verbatim in
// Issue.Extra and never reads them — the format's ownership table draws the
// same line. A field spelled in three call sites is a field that gets renamed
// in two.
const (
	// GiteaKey is the handle in the tracker: owner/repo#42, a wire.Key written
	// out. Cross-repo on purpose — a number alone is only unique inside one
	// repository, and an issue that has been moved, or a store that has ever
	// pointed at two repositories, needs the answer to say which.
	GiteaKey = "gitea"
	// URLKey is the issue's web address, for a receipt a human can click.
	URLKey = "url"
	// SyncedKey is when this copy was last written from or to the tracker —
	// how old the working copy is, and nothing more.
	SyncedKey = "synced"
	// RemoteUpdatedKey is the tracker's own updated_at.
	RemoteUpdatedKey = "remote-updated"
	// CommentsKey is how many comments the tracker holds, so a reader knows a
	// thread exists without fetching it.
	CommentsKey = "comments"
	// BranchKey is Gitea's `ref` — the branch an issue is pinned to. Its value
	// is a git branch name and means exactly `ref`, which is what makes it a
	// sync field rather than a domain one.
	BranchKey = "branch"
)

// RemoteKeyOf is the handle an issue carries, and whether it carries one at
// all.
//
// ok is false for anything that is not a handle: an empty field on a
// never-pushed issue, a line somebody hand-edited, a key written by a format
// that predates this one — and a bare `#42`, which names a number without the
// repository that makes it mean something. Callers act on ok rather than on a
// zero number, because "#0" and "not synced" would otherwise be the same
// answer.
func RemoteKeyOf(i *issue.Issue) (key wire.Key, ok bool) {
	k, err := wire.ParseKey(i.Extra[GiteaKey])
	if err != nil || k.Repo.Zero() {
		return wire.Key{}, false
	}
	return k, true
}

// NumberOf is the Gitea number of an already-synced issue; ok is false for one
// that has never been pushed.
func NumberOf(i *issue.Issue) (number int, ok bool) {
	k, ok := RemoteKeyOf(i)
	return k.Number, ok
}