// Package config 加载服务配置：.env / 环境变量 / 默认值（viper）。
// 所有项均可用环境变量 OT_<KEY> 覆盖（点号转下划线，如 db.driver → OT_DB_DRIVER）。
package config

import (
	"os"
	"strings"
	"time"

	"github.com/spf13/viper"
)

type Config struct {
	Env       string // development | production
	Port      int
	DB        DBConfig
	JWT       JWTConfig
	Auth      AuthConfig
	Proxy     ProxyConfig
	RateLimit RateLimitConfig
	WebAuthn  WebAuthnConfig
	Master    string // 渠道密钥 AES-GCM 主密钥（来自环境变量）
}

// WebAuthnConfig Passkey（WebAuthn）配置。
type WebAuthnConfig struct {
	RPID     string // Relying Party ID（域名，如 localhost）
	RPOrigin string // 前端来源，如 http://localhost:5173
	RPName   string // 展示名
}

// RateLimitConfig 限流参数（MVP 内存计数，Redis 后置）。
type RateLimitConfig struct {
	UserRPS int // 用户级每秒请求数上限（0=不限制）
}

type DBConfig struct {
	Driver string // sqlite | postgres
	DSN    string
}

type JWTConfig struct {
	Secret       string
	AccessTTL    time.Duration
	RefreshTTL   time.Duration
	Issuer       string
	CookieName   string
	CookieSecure bool
	CookieDomain string
}

type AuthConfig struct {
	RegistrationMode string // open | invite
	Argon2Time       uint32
	Argon2Memory     uint32
	Argon2Threads    uint8
	Argon2KeyLen     uint32
	SaltLen          int
}

type ProxyConfig struct {
	DefaultChannelName string // 首次启动自动创建的渠道名（如 openai）
	UpstreamBaseURL    string // 渠道 base_url 默认值
	UpstreamKey        string // 渠道上游 key 默认值
	DefaultModel       string // 渠道模型导入时使用的模型名
	Timeout            time.Duration
	HealthInterval     time.Duration // 渠道健康检查周期
	HealthFailThreshold int          // 连续失败 N 次进 cooldown
}

// loadDotEnv 读取 .env 并把 KEY=VALUE 注入环境变量（AutomaticEnv 自动映射 OT_ 前缀）。
// 已存在的环境变量优先，不覆盖。
func loadDotEnv() {
	data, err := os.ReadFile(".env")
	if err != nil {
		return
	}
	for _, line := range strings.Split(string(data), "\n") {
		line = strings.TrimSpace(line)
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		k, v, ok := strings.Cut(line, "=")
		if !ok {
			continue
		}
		k = strings.TrimSpace(k)
		v = strings.Trim(strings.TrimSpace(v), `"'`)
		if k != "" && os.Getenv(k) == "" {
			_ = os.Setenv(k, v)
		}
	}
}

func Load() (*Config, error) {
	loadDotEnv()

	v := viper.New()
	v.SetEnvPrefix("OT")
	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
	v.AutomaticEnv()

	// 默认值（与 .env.example 对应）
	v.SetDefault("env", "development")
	v.SetDefault("port", 8080)

	v.SetDefault("db.driver", "sqlite")
	v.SetDefault("db.dsn", "data/openteam.db")

	v.SetDefault("jwt.secret", "dev-only-secret-change-me")
	v.SetDefault("jwt.access_ttl", "2h")
	v.SetDefault("jwt.refresh_ttl", "168h")
	v.SetDefault("jwt.issuer", "openteam")
	v.SetDefault("jwt.cookie_name", "ot_refresh")
	v.SetDefault("jwt.cookie_secure", false)
	v.SetDefault("jwt.cookie_domain", "")

	v.SetDefault("auth.registration_mode", "open")
	v.SetDefault("auth.argon2_time", 3)
	v.SetDefault("auth.argon2_memory", 64*1024) // 64 MiB
	v.SetDefault("auth.argon2_threads", 2)
	v.SetDefault("auth.argon2_keylen", 32)
	v.SetDefault("auth.salt_len", 16)

	v.SetDefault("proxy.default_channel_name", "openai")
	v.SetDefault("proxy.upstream_base_url", "https://api.openai.com")
	v.SetDefault("proxy.upstream_key", "")
	v.SetDefault("proxy.default_model", "gpt-4o-mini")
	v.SetDefault("proxy.timeout", "120s")
	v.SetDefault("proxy.health_interval", "60s")
	v.SetDefault("proxy.health_fail_threshold", 2)

	v.SetDefault("ratelimit.user_rps", 20)

	v.SetDefault("webauthn.rp_id", "localhost")
	v.SetDefault("webauthn.rp_origin", "http://localhost:5173")
	v.SetDefault("webauthn.rp_name", "openteam")

	return &Config{
		Env:  v.GetString("env"),
		Port: v.GetInt("port"),
		DB: DBConfig{
			Driver: v.GetString("db.driver"),
			DSN:    v.GetString("db.dsn"),
		},
		JWT: JWTConfig{
			Secret:       v.GetString("jwt.secret"),
			AccessTTL:    v.GetDuration("jwt.access_ttl"),
			RefreshTTL:   v.GetDuration("jwt.refresh_ttl"),
			Issuer:       v.GetString("jwt.issuer"),
			CookieName:   v.GetString("jwt.cookie_name"),
			CookieSecure: v.GetBool("jwt.cookie_secure"),
			CookieDomain: v.GetString("jwt.cookie_domain"),
		},
		Auth: AuthConfig{
			RegistrationMode: v.GetString("auth.registration_mode"),
			Argon2Time:       v.GetUint32("auth.argon2_time"),
			Argon2Memory:     v.GetUint32("auth.argon2_memory"),
			Argon2Threads:    v.GetUint8("auth.argon2_threads"),
			Argon2KeyLen:     v.GetUint32("auth.argon2_keylen"),
			SaltLen:          v.GetInt("auth.salt_len"),
		},
		Proxy: ProxyConfig{
			DefaultChannelName:  v.GetString("proxy.default_channel_name"),
			UpstreamBaseURL:     v.GetString("proxy.upstream_base_url"),
			UpstreamKey:         v.GetString("proxy.upstream_key"),
			DefaultModel:        v.GetString("proxy.default_model"),
			Timeout:             v.GetDuration("proxy.timeout"),
			HealthInterval:      v.GetDuration("proxy.health_interval"),
			HealthFailThreshold: v.GetInt("proxy.health_fail_threshold"),
		},
		RateLimit: RateLimitConfig{
			UserRPS: v.GetInt("ratelimit.user_rps"),
		},
		WebAuthn: WebAuthnConfig{
			RPID:     v.GetString("webauthn.rp_id"),
			RPOrigin: v.GetString("webauthn.rp_origin"),
			RPName:   v.GetString("webauthn.rp_name"),
		},
		Master: v.GetString("master_key"),
	}, nil
}