package hostguard

import (
	"context"

	"github.com/carlosframework/platform/internal/hostclaim"
)

// WithServingRetirement holds both root and shared host locks. Unlike Work,
// retirement may precede installation of the newly admitted stamp. The callback
// must authenticate the older installation and stop receipts before effects.
// It must not call a lock-taking Guard or RootAuthority method.
func (g Guard) WithServingRetirement(ctx context.Context, host string, current Captured, fn func(hostclaim.Observed, FenceView) error) error {
	if ctx == nil || g.Root == nil || g.FenceView != nil || current.Incarnation == "" || current.Stamp == 0 || fn == nil {
		return ErrInvalidInput
	}
	return g.locked(ctx, host, func(d *recordDir) error {
		o, err := g.freshObserved(ctx, host)
		if err != nil {
			return err
		}
		c, h := o.Claim, o.Claim.Holder
		if h.Incarnation != current.Incarnation || h.Stamp != current.Stamp || h.Session != current.Stamp || c.Op.Kind != hostclaim.KindServing || c.Op.ID != "" || c.Op.Phase != "" {
			return ErrStampMismatch
		}
		r, err := d.read(host)
		if err != nil {
			return err
		}
		if r.quarantined || r.pendingInstallation != nil || r.barrier != nil {
			return ErrFenced
		}
		if r.ActiveFence != nil {
			completed := false
			for _, receipt := range r.FenceJournal {
				completed = completed || receipt.Target == *r.ActiveFence
			}
			if !completed || r.ActiveFence.Incarnation != current.Incarnation || r.ActiveFence.Stamp >= current.Stamp {
				return ErrFenced
			}
		}
		if r.Incarnation != current.Incarnation || r.ActiveStamp == 0 || r.ActiveStamp > current.Stamp {
			return ErrStampMismatch
		}
		for _, retired := range r.rootRetired {
			if retired == current {
				return ErrRetiredStamp
			}
		}
		for _, receipt := range r.FenceJournal {
			if receipt.Target.matchesSession(c, current) {
				return ErrFenced
			}
		}
		view, err := g.Root.viewLocked(host, Captured{Incarnation: r.Incarnation, Stamp: r.ActiveStamp})
		if err != nil {
			return err
		}
		if err = view.validate(host, view.Captured); err != nil {
			return err
		}
		if err = ctx.Err(); err != nil {
			return err
		}
		return fn(o, view)
	})
}