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)

	addr, ok := os.LookupEnv(internalHTTPAddrEnvVar)
	if !ok || strings.TrimSpace(addr) == "" {
		return Config{}, fmt.Errorf("%s must be set", internalHTTPAddrEnvVar)
	}
	cfg.InternalHTTP.Addr = strings.TrimSpace(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
	}

	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.LobbyEvents = stringEnv(lobbyEventsStreamEnvVar, cfg.Streams.LobbyEvents)
	cfg.Streams.HealthEvents = stringEnv(healthEventsStreamEnvVar, cfg.Streams.HealthEvents)
	cfg.Streams.NotificationIntents = stringEnv(notificationIntentsStreamEnvVar, cfg.Streams.NotificationIntents)
	cfg.Streams.BlockTimeout, err = durationEnv(streamBlockTimeoutEnvVar, cfg.Streams.BlockTimeout)
	if err != nil {
		return Config{}, err
	}

	cfg.EngineClient.CallTimeout, err = durationEnv(engineCallTimeoutEnvVar, cfg.EngineClient.CallTimeout)
	if err != nil {
		return Config{}, err
	}
	cfg.EngineClient.ProbeTimeout, err = durationEnv(engineProbeTimeoutEnvVar, cfg.EngineClient.ProbeTimeout)
	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
	}

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

	cfg.Scheduler.TickInterval, err = durationEnv(schedulerTickIntervalEnvVar, cfg.Scheduler.TickInterval)
	if err != nil {
		return Config{}, err
	}
	cfg.Scheduler.TurnGenerationTimeout, err = durationEnv(turnGenerationTimeoutEnvVar, cfg.Scheduler.TurnGenerationTimeout)
	if err != nil {
		return Config{}, err
	}

	cfg.MembershipCache.TTL, err = durationEnv(membershipCacheTTLEnvVar, cfg.MembershipCache.TTL)
	if err != nil {
		return Config{}, err
	}
	cfg.MembershipCache.MaxGames, err = intEnv(membershipCacheMaxGamesEnvVar, cfg.MembershipCache.MaxGames)
	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 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 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 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)
}