package hostguard

import (
	"context"
	"os"
	"path/filepath"
	"strings"
)

func (g Guard) PendingFences(ctx context.Context) ([]FenceTarget, error) {
	return g.pendingFences(ctx, true)
}

func (g Guard) PendingStopFences(ctx context.Context) ([]FenceTarget, error) {
	return g.pendingFences(ctx, false)
}

func (g Guard) pendingFences(ctx context.Context, handovers bool) ([]FenceTarget, error) {
	if g.FenceView != nil {
		return nil, ErrUnsupported
	}
	names, err := g.recordNames()
	if err != nil {
		return nil, err
	}
	var out []FenceTarget
	for _, name := range names {
		if !strings.HasSuffix(name, ".json") {
			continue
		}
		host := strings.TrimSuffix(name, ".json")
		err := g.readLocked(ctx, host, func(d *recordDir) error {
			r, err := d.read(host)
			if err != nil {
				return err
			}
			if r.ActiveFence == nil || (!handovers && r.root && r.barrier != nil && *r.barrier == *r.ActiveFence) {
				return nil
			}
			for _, receipt := range r.FenceJournal {
				if receipt.Target == *r.ActiveFence {
					return nil
				}
			}
			out = append(out, *r.ActiveFence)
			return nil
		})
		if err != nil {
			return nil, err
		}
	}
	return out, nil
}
func (g Guard) ResumeFence(ctx context.Context, target FenceTarget) error {
	return g.fenceLocked(ctx, target.Host, Captured{Incarnation: target.Incarnation, Stamp: target.Stamp}, func(d *recordDir) error {
		r, err := d.read(target.Host)
		if err != nil {
			return err
		}
		if r.ActiveFence == nil || *r.ActiveFence != target {
			return ErrFenceTarget
		}
		return nil
	})
}

func (g Guard) ExistingFence(ctx context.Context, want FenceTarget) (FenceTarget, error) {
	var found FenceTarget
	err := g.fenceLocked(ctx, want.Host, Captured{Incarnation: want.Incarnation, Stamp: want.Stamp}, func(d *recordDir) error {
		r, err := d.read(want.Host)
		if err != nil {
			return err
		}
		if r.ActiveFence == nil || !r.ActiveFence.sameAuthority(want) {
			return ErrFenceTarget
		}
		found = *r.ActiveFence
		return nil
	})
	return found, err
}

func (g Guard) recordNames() ([]string, error) {
	if g.Root != nil {
		return g.Root.store.Names()
	}
	entries, err := os.ReadDir(filepath.Join(g.DataDir, "hostguard"))
	if err != nil {
		return nil, err
	}
	var names []string
	for _, entry := range entries {
		if !entry.IsDir() {
			names = append(names, entry.Name())
		}
	}
	return names, nil
}