// Package config 提供 Agent 与 Gateway 的配置加载（环境变量优先，内置默认值）。
package config

import (
	"os"
	"strconv"
	"strings"
	"time"
)

// AgentConfig 是 Agent 端运行配置。
type AgentConfig struct {
	HostID       string
	AgentVersion string
	Service      string

	GatewayURL string
	AgentToken string

	LogFiles []string

	CoreInterval    time.Duration
	DiskInterval    time.Duration
	NetworkInterval time.Duration
	ProcessInterval time.Duration

	BatchSize    int
	FlushInterval time.Duration

	CheckpointDriver string // memory | file | redis
	CheckpointFile   string
	RedisURL         string

	CollectTimeout time.Duration
}

// DefaultAgentConfig 返回 Agent 默认配置。
func DefaultAgentConfig() AgentConfig {
	return AgentConfig{
		HostID:           env("HMS_HOST_ID", "host-001"),
		AgentVersion:     env("HMS_AGENT_VERSION", "0.1.0"),
		Service:          env("HMS_SERVICE", "host"),
		GatewayURL:       env("HMS_GATEWAY_URL", "http://127.0.0.1:4318"),
		AgentToken:       env("HMS_AGENT_TOKEN", "dev-token"),
		LogFiles:         splitCSV(env("HMS_LOG_FILES", "")),
		CoreInterval:     durEnv("HMS_CORE_INTERVAL", 15*time.Second),
		DiskInterval:     durEnv("HMS_DISK_INTERVAL", 30*time.Second),
		NetworkInterval:  durEnv("HMS_NETWORK_INTERVAL", 30*time.Second),
		ProcessInterval:  durEnv("HMS_PROCESS_INTERVAL", 60*time.Second),
		BatchSize:        intEnv("HMS_BATCH_SIZE", 128),
		FlushInterval:    durEnv("HMS_FLUSH_INTERVAL", 10*time.Second),
		CheckpointDriver: env("HMS_CHECKPOINT_DRIVER", "file"),
		CheckpointFile:   env("HMS_CHECKPOINT_FILE", "checkpoint.json"),
		RedisURL:         env("HMS_REDIS_URL", "redis://127.0.0.1:6379/0"),
		CollectTimeout:   durEnv("HMS_COLLECT_TIMEOUT", 5*time.Second),
	}
}

// GatewayConfig 是服务端 Collector Gateway 配置。
type GatewayConfig struct {
	Addr       string
	AgentToken string

	// 查询内存存储的保留上限。
	MaxMetricsPerHost int
	MaxLogsPerHost    int

	RedisURL string
}

// DefaultGatewayConfig 返回 Gateway 默认配置。
func DefaultGatewayConfig() GatewayConfig {
	return GatewayConfig{
		Addr:              env("HMS_GATEWAY_ADDR", "0.0.0.0:4318"),
		AgentToken:        env("HMS_AGENT_TOKEN", "dev-token"),
		MaxMetricsPerHost: intEnv("HMS_MAX_METRICS_PER_HOST", 20000),
		MaxLogsPerHost:    intEnv("HMS_MAX_LOGS_PER_HOST", 20000),
		RedisURL:          env("HMS_REDIS_URL", "redis://127.0.0.1:6379/0"),
	}
}

func env(key, def string) string {
	if v, ok := os.LookupEnv(key); ok && v != "" {
		return v
	}
	return def
}

func durEnv(key string, def time.Duration) time.Duration {
	if v, ok := os.LookupEnv(key); ok && v != "" {
		if d, err := time.ParseDuration(v); err == nil {
			return d
		}
	}
	return def
}

func intEnv(key string, def int) int {
	if v, ok := os.LookupEnv(key); ok && v != "" {
		if n, err := strconv.Atoi(v); err == nil {
			return n
		}
	}
	return def
}

func splitCSV(v string) []string {
	if v == "" {
		return nil
	}
	parts := strings.Split(v, ",")
	out := make([]string, 0, len(parts))
	for _, p := range parts {
		if p = strings.TrimSpace(p); p != "" {
			out = append(out, p)
		}
	}
	return out
}