package host

import (
	"github.com/carlosframework/platform/internal/cgroup"
	"github.com/carlosframework/platform/internal/registry"
	"github.com/carlosframework/platform/internal/release"
)

// memTier builds the exec backend's Tier seam from a manifest reader —
// on a box, stagedManifestOfLiveVersion, the same reader the caps pass
// uses, so "what does this app declare" has one answer on the box.
//
// One bit decides it: capabilities.children → the 1G tier a forking family
// gets on the unit path (caps/render.go); anything else → 512M, the
// carlos-app@ template's number. A missing or unreadable sibling is the
// default tier, not an error: the smaller cap is the safe direction, and
// the caps pass already reports the unreadable sibling in its own advice.
func memTier(load func(registry.Route) (*release.Manifest, error)) func(registry.Route) cgroup.Limit {
	return func(rt registry.Route) cgroup.Limit {
		m, err := load(rt)
		if err != nil || m == nil || m.Capabilities == nil || !m.Capabilities.Children {
			return cgroup.TierDefault
		}
		return cgroup.TierChildren
	}
}

// memTierOf is memTier for one named version: that version's staged
// manifest, never the live link's (zero-downtime spec §7.3: a generation's
// limits are its own artifact's). A staged copy is immutable once anything
// refers to it (plan 4), so the answer for a version does not move.
func memTierOf(load func(rt registry.Route, version string) (*release.Manifest, error)) func(registry.Route, string) cgroup.Limit {
	return func(rt registry.Route, version string) cgroup.Limit {
		return memTier(func(rt registry.Route) (*release.Manifest, error) { return load(rt, version) })(rt)
	}
}