package cluster

var (
	_ MachineIterator = (*Region)(nil)
	_ ZoneIterator    = (*Region)(nil)
)

// Region represents a group of zones geographically related
type Region struct {
	m     *Cluster
	zones []*Zone

	Name    string
	Regions []string `json:",omitempty" yaml:",omitempty"`
}

// ForEachRegion calls a function for each Region of the cluster
// until instructed to terminate the loop
func (m *Cluster) ForEachRegion(fn func(r *Region) bool) {
	for i := range m.Regions {
		r := &m.Regions[i]
		if fn(r) {
			return
		}
	}
}

// ForEachMachine calls a function for each Machine in the region
// until instructed to terminate the loop
func (r *Region) ForEachMachine(fn func(*Machine) bool) {
	r.ForEachZone(func(z *Zone) bool {
		var term bool

		z.ForEachMachine(func(p *Machine) bool {
			if p.IsActive() {
				term = fn(p)
			}
			return term
		})

		return term
	})
}

// ForEachZone calls a function for each Zone in the region
// until instructed to terminate the loop
func (r *Region) ForEachZone(fn func(*Zone) bool) {
	for _, p := range r.zones {
		if fn(p) {
			// terminate
			return
		}
	}
}

func (m *Cluster) initRegions(_ *ScanOptions) error {
	regions := make(map[string][]*Zone)

	// first regions defined by zones
	m.ForEachZone(func(z *Zone) bool {
		SortRegions(z.Regions)
		for _, region := range z.Regions {
			regions[region] = append(regions[region], z)
		}

		return false
	})

	// bind first level regions and their zones
	for name, zones := range regions {
		m.syncRegions(name, zones...)
	}

	// and combine zones to produce larger regions
	for i := range m.Regions {
		r := &m.Regions[i]
		m.finishRegion(r)
	}

	m.sortRegions()
	return nil
}

func (m *Cluster) syncRegions(name string, zones ...*Zone) {
	for _, r := range m.Regions {
		if r.Name == name {
			// found
			r.m = m
			r.zones = zones
			return
		}
	}

	// new
	m.Regions = append(m.Regions, Region{
		m:     m,
		zones: zones,
		Name:  name,
	})
}

func (m *Cluster) finishRegion(r *Region) {
	if r.m != nil {
		// ready
		return
	}

	r.m = m
	sub := []string{}
	for _, name := range r.Regions {
		r2, ok := m.getRegion(name)
		if !ok {
			m.warn(nil).WithField("region", name).Print("unknown region")
			continue
		}

		sub = append(sub, r2.Name)
		r.zones = append(r.zones, r2.zones...)
	}
	r.Regions = sub
}

func (m *Cluster) getRegion(name string) (*Region, bool) {
	for i := range m.Regions {
		r := &m.Regions[i]

		if name == r.Name {
			m.finishRegion(r)
			return r, true
		}
	}

	return nil, false
}