package zones

import (
	"io/fs"
	"sort"
)

func (m *Zones) scan() error {
	for _, fn := range []func() error{
		m.scanDirectory,
		m.scanMachines,
		m.scanZoneIDs,
		m.scanSort,
	} {
		if err := fn(); err != nil {
			return err
		}
	}

	return nil
}

func (m *Zones) scanDirectory() error {
	// each directory is a zone
	entries, err := fs.ReadDir(m.dir, ".")
	if err != nil {
		return err
	}

	for _, e := range entries {
		if e.IsDir() {
			z := &Zone{
				zones: m,
				Name:  e.Name(),
			}

			if err := z.scan(); err != nil {
				return err
			}

			m.Zones = append(m.Zones, z)
		}
	}

	return nil
}

func (m *Zones) scanMachines() error {
	var err error
	m.ForEachMachine(func(p *Machine) bool {
		err = p.scan()
		return err != nil
	})
	return err
}

func (m *Zones) scanZoneIDs() error {
	var hasMissing bool
	var lastZoneID int

	m.ForEachZone(func(z *Zone) bool {
		switch {
		case z.ID == 0:
			hasMissing = true
		case z.ID > lastZoneID:
			lastZoneID = z.ID
		}

		return false
	})

	if hasMissing {
		next := lastZoneID + 1

		m.ForEachZone(func(z *Zone) bool {
			if z.ID == 0 {
				z.ID, next = next, next+1
			}

			return false
		})
	}

	return nil
}

func (m *Zones) scanSort() error {
	sort.SliceStable(m.Zones, func(i, j int) bool {
		id1 := m.Zones[i].ID
		id2 := m.Zones[j].ID
		return id1 < id2
	})

	m.ForEachZone(func(z *Zone) bool {
		sort.SliceStable(z.Machines, func(i, j int) bool {
			id1 := z.Machines[i].ID()
			id2 := z.Machines[j].ID()
			return id1 < id2
		})

		return false
	})

	m.ForEachMachine(func(p *Machine) bool {
		sort.SliceStable(p.RingAddresses, func(i, j int) bool {
			ri1 := p.RingAddresses[i]
			ri2 := p.RingAddresses[j]

			return ri1.Ring < ri2.Ring
		})

		return false
	})

	return nil
}

func (z *Zone) scan() error {
	// each directory is a machine
	entries, err := fs.ReadDir(z.zones.dir, z.Name)
	if err != nil {
		return err
	}

	for _, e := range entries {
		if e.IsDir() {
			m := &Machine{
				zone: z,
				Name: e.Name(),
			}

			if err := m.init(); err != nil {
				return err
			}

			z.Machines = append(z.Machines, m)
		}
	}

	return nil
}