package service

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

// Settings configures the Metis service runtime.
type Settings struct {
	BindAddr          string
	InventoryPath     string
	CacheDir          string
	ArtifactDir       string
	ArtifactStatePath string
	HistoryPath       string
	SnapshotsPath     string
	TargetsPath       string
	DefaultFlashHost  string
	FlashHosts        []string
	LocalHost         string
	AllowedGroups     []string
	MaxDeviceBytes    int64
	Namespace         string
	RunnerImageAMD64  string
	RunnerImageARM64  string
	HarborRegistry    string
	HarborProject     string
	HarborAPIBase     string
	HarborUsername    string
	HarborPassword    string
	HostTmpDir        string
}

// FromEnv builds service settings with sensible defaults for local dev and in-cluster use.
func FromEnv() Settings {
	dataDir := getenvDefault("METIS_DATA_DIR", "/var/lib/metis")
	localHost := getenvDefault("METIS_LOCAL_HOST", hostnameOr("unknown"))
	defaultFlashHost := getenvDefault("METIS_DEFAULT_FLASH_HOST", localHost)
	flashHosts := splitList(getenvDefault("METIS_FLASH_HOSTS", defaultFlashHost))
	return Settings{
		BindAddr:          getenvDefault("METIS_BIND_ADDR", ":8080"),
		InventoryPath:     getenvDefault("METIS_INVENTORY_PATH", "inventory.titan-rpi4.yaml"),
		CacheDir:          getenvDefault("METIS_CACHE_DIR", filepath.Join(dataDir, "cache")),
		ArtifactDir:       getenvDefault("METIS_ARTIFACT_DIR", filepath.Join(dataDir, "artifacts")),
		ArtifactStatePath: getenvDefault("METIS_ARTIFACT_STATE_PATH", filepath.Join(dataDir, "artifacts.json")),
		HistoryPath:       getenvDefault("METIS_HISTORY_PATH", filepath.Join(dataDir, "history.jsonl")),
		SnapshotsPath:     getenvDefault("METIS_SNAPSHOTS_PATH", filepath.Join(dataDir, "snapshots.json")),
		TargetsPath:       getenvDefault("METIS_TARGETS_PATH", filepath.Join(dataDir, "targets.json")),
		DefaultFlashHost:  defaultFlashHost,
		FlashHosts:        flashHosts,
		LocalHost:         localHost,
		AllowedGroups:     splitList(getenvDefault("METIS_ALLOWED_GROUPS", "admin,maintenance")),
		MaxDeviceBytes:    getenvInt64("METIS_MAX_DEVICE_BYTES", 300000000000),
		Namespace:         getenvDefault("METIS_NAMESPACE", "maintenance"),
		RunnerImageAMD64:  getenvDefault("METIS_RUNNER_IMAGE_AMD64", ""),
		RunnerImageARM64:  getenvDefault("METIS_RUNNER_IMAGE_ARM64", ""),
		HarborRegistry:    getenvDefault("METIS_HARBOR_REGISTRY", "registry.bstein.dev"),
		HarborProject:     getenvDefault("METIS_HARBOR_PROJECT", "metis"),
		HarborAPIBase:     getenvDefault("METIS_HARBOR_API_BASE", "https://registry.bstein.dev/api/v2.0"),
		HarborUsername:    getenvDefault("METIS_HARBOR_USERNAME", ""),
		HarborPassword:    getenvDefault("METIS_HARBOR_PASSWORD", ""),
		HostTmpDir:        getenvDefault("METIS_HOST_TMP_DIR", "/tmp/metis-flash-test"),
	}
}

func getenvDefault(key, fallback string) string {
	if value := strings.TrimSpace(os.Getenv(key)); value != "" {
		return value
	}
	return fallback
}

func getenvInt64(key string, fallback int64) int64 {
	raw := strings.TrimSpace(os.Getenv(key))
	if raw == "" {
		return fallback
	}
	value, err := strconv.ParseInt(raw, 10, 64)
	if err != nil {
		return fallback
	}
	return value
}

func splitList(raw string) []string {
	if strings.TrimSpace(raw) == "" {
		return nil
	}
	parts := strings.Split(raw, ",")
	result := make([]string, 0, len(parts))
	for _, part := range parts {
		part = strings.TrimSpace(part)
		if part == "" {
			continue
		}
		result = append(result, part)
	}
	return result
}

func hostnameOr(fallback string) string {
	name, err := os.Hostname()
	if err != nil || strings.TrimSpace(name) == "" {
		return fallback
	}
	return strings.TrimSpace(name)
}