package arvados

import (
	"fmt"
	"os"
	"strings"

	"git.curoverse.com/arvados.git/sdk/go/config"
)

type Config struct {
	Clusters map[string]Cluster
}

// GetConfig returns the current system config, loading it from
// /etc if needed.
func GetConfig() (*Config, error) {
	var cfg Config
	err := config.LoadFile(&cfg, "/etc/arvados/config.yml")
	return &cfg, err
}

// GetCluster returns the cluster ID and config for the given
// cluster, or the default/only configured cluster if clusterID is "".
func (sc *Config) GetCluster(clusterID string) (*Cluster, error) {
	if clusterID == "" {
		if len(sc.Clusters) == 0 {
			return nil, fmt.Errorf("no clusters configured")
		} else if len(sc.Clusters) > 1 {
			return nil, fmt.Errorf("multiple clusters configured, cannot choose")
		} else {
			for id, cc := range sc.Clusters {
				cc.ClusterID = id
				return &cc, nil
			}
		}
	}
	if cc, ok := sc.Clusters[clusterID]; !ok {
		return nil, fmt.Errorf("cluster %q is not configured", clusterID)
	} else {
		cc.ClusterID = clusterID
		return &cc, nil
	}
}

type Cluster struct {
	ClusterID       string `json:"-"`
	ManagementToken string
	SystemNodes     map[string]SystemNode
}

// GetThisSystemNodeConfig returns a SystemNode for the node we're
// running on right now.
func (cc *Cluster) GetThisSystemNode() (*SystemNode, error) {
	hostname, err := os.Hostname()
	if err != nil {
		return nil, err
	}
	return cc.GetSystemNode(hostname)
}

// GetSystemNodeConfig returns a NodeConfig for the given node. An
// error is returned if the appropriate configuration can't be
// determined (e.g., this does not appear to be a system node).
func (cc *Cluster) GetSystemNode(node string) (*SystemNode, error) {
	// Generally node is "a.b.ca", use the first of {"a.b.ca",
	// "a.b", "a"} that has an entry in SystemNodes.
	labels := strings.Split(node, ".")
	for j := len(labels); j > 0; j-- {
		hostpart := strings.Join(labels[:j], ".")
		if cfg, ok := cc.SystemNodes[hostpart]; ok {
			return &cfg, nil
		}
	}
	// If node is not listed, but "*" gives a default system node
	// config, use the default config.
	if cfg, ok := cc.SystemNodes["*"]; ok {
		return &cfg, nil
	}
	return nil, fmt.Errorf("config does not provision host %q as a system node", node)
}

type SystemNode struct {
	Health    Health
	Keepstore Keepstore
}

type Health struct {
	Listen string
}

type Keepstore struct {
	Listen string
}