package config

import (
	"fmt"
	"os"
	"strconv"
	"strings"
	"time"

	"galaxy/postgres"
	"galaxy/redisconn"
)

// LoadFromEnv builds Config from environment variables and validates the
// resulting configuration.
func LoadFromEnv() (Config, error) {
	cfg := DefaultConfig()

	var err error

	cfg.ShutdownTimeout, err = durationEnv(shutdownTimeoutEnvVar, cfg.ShutdownTimeout)
	if err != nil {
		return Config{}, err
	}

	cfg.Logging.Level = stringEnv(logLevelEnvVar, cfg.Logging.Level)

	cfg.InternalHTTP.Addr = stringEnv(internalHTTPAddrEnvVar, cfg.InternalHTTP.Addr)
	cfg.InternalHTTP.ReadHeaderTimeout, err = durationEnv(internalHTTPReadHeaderTimeoutEnvVar, cfg.InternalHTTP.ReadHeaderTimeout)
	if err != nil {
		return Config{}, err
	}
	cfg.InternalHTTP.ReadTimeout, err = durationEnv(internalHTTPReadTimeoutEnvVar, cfg.InternalHTTP.ReadTimeout)
	if err != nil {
		return Config{}, err
	}
	cfg.InternalHTTP.WriteTimeout, err = durationEnv(internalHTTPWriteTimeoutEnvVar, cfg.InternalHTTP.WriteTimeout)
	if err != nil {
		return Config{}, err
	}
	cfg.InternalHTTP.IdleTimeout, err = durationEnv(internalHTTPIdleTimeoutEnvVar, cfg.InternalHTTP.IdleTimeout)
	if err != nil {
		return Config{}, err
	}

	cfg.Docker.Host = stringEnv(dockerHostEnvVar, cfg.Docker.Host)
	cfg.Docker.APIVersion = stringEnv(dockerAPIVersionEnvVar, cfg.Docker.APIVersion)
	cfg.Docker.Network = stringEnv(dockerNetworkEnvVar, cfg.Docker.Network)
	cfg.Docker.LogDriver = stringEnv(dockerLogDriverEnvVar, cfg.Docker.LogDriver)
	cfg.Docker.LogOpts = stringEnv(dockerLogOptsEnvVar, cfg.Docker.LogOpts)
	if raw, ok := os.LookupEnv(imagePullPolicyEnvVar); ok {
		cfg.Docker.PullPolicy = ImagePullPolicy(strings.TrimSpace(raw))
	}

	pgConn, err := postgres.LoadFromEnv(envPrefix)
	if err != nil {
		return Config{}, err
	}
	cfg.Postgres.Conn = pgConn

	redisConn, err := redisconn.LoadFromEnv(envPrefix)
	if err != nil {
		return Config{}, err
	}
	cfg.Redis.Conn = redisConn

	cfg.Streams.StartJobs = stringEnv(startJobsStreamEnvVar, cfg.Streams.StartJobs)
	cfg.Streams.StopJobs = stringEnv(stopJobsStreamEnvVar, cfg.Streams.StopJobs)
	cfg.Streams.JobResults = stringEnv(jobResultsStreamEnvVar, cfg.Streams.JobResults)
	cfg.Streams.HealthEvents = stringEnv(healthEventsStreamEnvVar, cfg.Streams.HealthEvents)
	cfg.Streams.NotificationIntents = stringEnv(notificationIntentsStreamEnv, cfg.Streams.NotificationIntents)
	cfg.Streams.BlockTimeout, err = durationEnv(streamBlockTimeoutEnvVar, cfg.Streams.BlockTimeout)
	if err != nil {
		return Config{}, err
	}

	cfg.Container.DefaultCPUQuota, err = floatEnv(defaultCPUQuotaEnvVar, cfg.Container.DefaultCPUQuota)
	if err != nil {
		return Config{}, err
	}
	cfg.Container.DefaultMemory = stringEnv(defaultMemoryEnvVar, cfg.Container.DefaultMemory)
	cfg.Container.DefaultPIDsLimit, err = intEnv(defaultPIDsLimitEnvVar, cfg.Container.DefaultPIDsLimit)
	if err != nil {
		return Config{}, err
	}
	cfg.Container.StopTimeout, err = secondsEnv(containerStopTimeoutSecondsEnvVar, cfg.Container.StopTimeout)
	if err != nil {
		return Config{}, err
	}
	cfg.Container.Retention, err = daysEnv(containerRetentionDaysEnvVar, cfg.Container.Retention)
	if err != nil {
		return Config{}, err
	}
	cfg.Container.EngineStateMountPath = stringEnv(engineStateMountPathEnvVar, cfg.Container.EngineStateMountPath)
	cfg.Container.EngineStateEnvName = stringEnv(engineStateEnvNameEnvVar, cfg.Container.EngineStateEnvName)
	cfg.Container.GameStateDirMode, err = octalUint32Env(gameStateDirModeEnvVar, cfg.Container.GameStateDirMode)
	if err != nil {
		return Config{}, err
	}
	cfg.Container.GameStateOwnerUID, err = intEnv(gameStateOwnerUIDEnvVar, cfg.Container.GameStateOwnerUID)
	if err != nil {
		return Config{}, err
	}
	cfg.Container.GameStateOwnerGID, err = intEnv(gameStateOwnerGIDEnvVar, cfg.Container.GameStateOwnerGID)
	if err != nil {
		return Config{}, err
	}
	root, ok := os.LookupEnv(gameStateRootEnvVar)
	if !ok || strings.TrimSpace(root) == "" {
		return Config{}, fmt.Errorf("%s must be set", gameStateRootEnvVar)
	}
	cfg.Container.GameStateRoot = strings.TrimSpace(root)

	cfg.Health.InspectInterval, err = durationEnv(inspectIntervalEnvVar, cfg.Health.InspectInterval)
	if err != nil {
		return Config{}, err
	}
	cfg.Health.ProbeInterval, err = durationEnv(probeIntervalEnvVar, cfg.Health.ProbeInterval)
	if err != nil {
		return Config{}, err
	}
	cfg.Health.ProbeTimeout, err = durationEnv(probeTimeoutEnvVar, cfg.Health.ProbeTimeout)
	if err != nil {
		return Config{}, err
	}
	cfg.Health.ProbeFailuresThreshold, err = intEnv(probeFailuresThresholdEnvVar, cfg.Health.ProbeFailuresThreshold)
	if err != nil {
		return Config{}, err
	}

	cfg.Cleanup.ReconcileInterval, err = durationEnv(reconcileIntervalEnvVar, cfg.Cleanup.ReconcileInterval)
	if err != nil {
		return Config{}, err
	}
	cfg.Cleanup.CleanupInterval, err = durationEnv(cleanupIntervalEnvVar, cfg.Cleanup.CleanupInterval)
	if err != nil {
		return Config{}, err
	}

	cfg.Coordination.GameLeaseTTL, err = secondsEnv(gameLeaseTTLSecondsEnvVar, cfg.Coordination.GameLeaseTTL)
	if err != nil {
		return Config{}, err
	}

	lobbyURL, ok := os.LookupEnv(lobbyInternalBaseURLEnvVar)
	if !ok || strings.TrimSpace(lobbyURL) == "" {
		return Config{}, fmt.Errorf("%s must be set", lobbyInternalBaseURLEnvVar)
	}
	cfg.Lobby.BaseURL = strings.TrimSpace(lobbyURL)
	cfg.Lobby.Timeout, err = durationEnv(lobbyInternalTimeoutEnvVar, cfg.Lobby.Timeout)
	if err != nil {
		return Config{}, err
	}

	cfg.Telemetry.ServiceName = stringEnv(otelServiceNameEnvVar, cfg.Telemetry.ServiceName)
	cfg.Telemetry.TracesExporter = normalizeExporterValue(stringEnv(otelTracesExporterEnvVar, cfg.Telemetry.TracesExporter))
	cfg.Telemetry.MetricsExporter = normalizeExporterValue(stringEnv(otelMetricsExporterEnvVar, cfg.Telemetry.MetricsExporter))
	cfg.Telemetry.TracesProtocol = normalizeProtocolValue(
		os.Getenv(otelExporterOTLPTracesProtocolEnvVar),
		os.Getenv(otelExporterOTLPProtocolEnvVar),
		cfg.Telemetry.TracesProtocol,
	)
	cfg.Telemetry.MetricsProtocol = normalizeProtocolValue(
		os.Getenv(otelExporterOTLPMetricsProtocolEnvVar),
		os.Getenv(otelExporterOTLPProtocolEnvVar),
		cfg.Telemetry.MetricsProtocol,
	)
	cfg.Telemetry.StdoutTracesEnabled, err = boolEnv(otelStdoutTracesEnabledEnvVar, cfg.Telemetry.StdoutTracesEnabled)
	if err != nil {
		return Config{}, err
	}
	cfg.Telemetry.StdoutMetricsEnabled, err = boolEnv(otelStdoutMetricsEnabledEnvVar, cfg.Telemetry.StdoutMetricsEnabled)
	if err != nil {
		return Config{}, err
	}

	if err := cfg.Validate(); err != nil {
		return Config{}, err
	}

	return cfg, nil
}

func stringEnv(name string, fallback string) string {
	value, ok := os.LookupEnv(name)
	if !ok {
		return fallback
	}

	return strings.TrimSpace(value)
}

func durationEnv(name string, fallback time.Duration) (time.Duration, error) {
	value, ok := os.LookupEnv(name)
	if !ok {
		return fallback, nil
	}

	parsed, err := time.ParseDuration(strings.TrimSpace(value))
	if err != nil {
		return 0, fmt.Errorf("%s: parse duration: %w", name, err)
	}

	return parsed, nil
}

func secondsEnv(name string, fallback time.Duration) (time.Duration, error) {
	value, ok := os.LookupEnv(name)
	if !ok {
		return fallback, nil
	}

	parsed, err := strconv.Atoi(strings.TrimSpace(value))
	if err != nil {
		return 0, fmt.Errorf("%s: parse seconds: %w", name, err)
	}
	if parsed <= 0 {
		return 0, fmt.Errorf("%s: must be positive", name)
	}

	return time.Duration(parsed) * time.Second, nil
}

func daysEnv(name string, fallback time.Duration) (time.Duration, error) {
	value, ok := os.LookupEnv(name)
	if !ok {
		return fallback, nil
	}

	parsed, err := strconv.Atoi(strings.TrimSpace(value))
	if err != nil {
		return 0, fmt.Errorf("%s: parse days: %w", name, err)
	}
	if parsed <= 0 {
		return 0, fmt.Errorf("%s: must be positive", name)
	}

	return time.Duration(parsed) * 24 * time.Hour, nil
}

func intEnv(name string, fallback int) (int, error) {
	value, ok := os.LookupEnv(name)
	if !ok {
		return fallback, nil
	}

	parsed, err := strconv.Atoi(strings.TrimSpace(value))
	if err != nil {
		return 0, fmt.Errorf("%s: parse int: %w", name, err)
	}

	return parsed, nil
}

func floatEnv(name string, fallback float64) (float64, error) {
	value, ok := os.LookupEnv(name)
	if !ok {
		return fallback, nil
	}

	parsed, err := strconv.ParseFloat(strings.TrimSpace(value), 64)
	if err != nil {
		return 0, fmt.Errorf("%s: parse float: %w", name, err)
	}

	return parsed, nil
}

func boolEnv(name string, fallback bool) (bool, error) {
	value, ok := os.LookupEnv(name)
	if !ok {
		return fallback, nil
	}

	parsed, err := strconv.ParseBool(strings.TrimSpace(value))
	if err != nil {
		return false, fmt.Errorf("%s: parse bool: %w", name, err)
	}

	return parsed, nil
}

func octalUint32Env(name string, fallback uint32) (uint32, error) {
	value, ok := os.LookupEnv(name)
	if !ok {
		return fallback, nil
	}

	parsed, err := strconv.ParseUint(strings.TrimSpace(value), 8, 32)
	if err != nil {
		return 0, fmt.Errorf("%s: parse octal: %w", name, err)
	}

	return uint32(parsed), nil
}

func normalizeExporterValue(value string) string {
	trimmed := strings.TrimSpace(value)
	switch trimmed {
	case "", "none":
		return "none"
	default:
		return trimmed
	}
}

func normalizeProtocolValue(primary string, fallback string, defaultValue string) string {
	primary = strings.TrimSpace(primary)
	if primary != "" {
		return primary
	}

	fallback = strings.TrimSpace(fallback)
	if fallback != "" {
		return fallback
	}

	return strings.TrimSpace(defaultValue)
}