package hostfence

import (
	"context"
	"github.com/carlosframework/platform/internal/hostclaim"
	"slices"
)

// CheckOneBoxRegion uses the same signed roster as fence authority. A fenced
// source still counts; neither a missing heartbeat nor a second fenced box
// turns a two-box placement into a one-box region.
func (a ClaimFenceAuthority) CheckOneBoxRegion(ctx context.Context, source, region string) error {
	o, err := a.Directory.Read(ctx)
	if err != nil {
		return err
	}
	b, ok := o.Roster.Boxes[source]
	if !ok || b.Region != region {
		return hostclaim.ErrFence
	}
	placement, ok := o.Roster.Regions[region]
	if !ok || placement.Account != b.Cloud.Account || placement.AWSRegion != b.Cloud.Region || !slices.Contains(placement.Namespaces, b.Namespace) || !slices.Contains(placement.Pools, b.Pool) {
		return hostclaim.ErrFence
	}
	count := 0
	for _, candidate := range o.Roster.Boxes {
		if candidate.Region == region && candidate.Namespace == b.Namespace && candidate.Pool == b.Pool && candidate.State != "retired" {
			count++
		}
	}
	if b.State == "retired" || count != 1 {
		return hostclaim.ErrFence
	}
	return nil
}