package config

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

	"gopkg.in/yaml.v3"
)

type Config struct {
	Server      ServerConfig      `yaml:"server"`
	Database    DatabaseConfig    `yaml:"database"`
	Admin       AdminConfig       `yaml:"admin"`
	Cache       CacheConfig       `yaml:"cache"`
	HealthCheck HealthCheckConfig `yaml:"health_check"`
	Security    SecurityConfig    `yaml:"security"`
	Gateway     GatewayConfig     `yaml:"gateway"`
}

type GatewayConfig struct {
	MaxRetries     int `yaml:"max_retries"`
	RetryBackoffMs int `yaml:"retry_backoff_ms"`
}

type ServerConfig struct {
	Addr string `yaml:"addr"`
}

type DatabaseConfig struct {
	Path string `yaml:"path"`
}

type AdminConfig struct {
	Username string `yaml:"username"`
	Password string `yaml:"password"`
}

type CacheConfig struct {
	UsageFlushInterval time.Duration `yaml:"usage_flush_interval"`
}

type HealthCheckConfig struct {
	Interval time.Duration `yaml:"interval"`
}

type SecurityConfig struct {
	EncryptionKey     string        `yaml:"encryption_key"`
	SessionTTL        time.Duration `yaml:"session_ttl"`
	IPAllowlist       []string      `yaml:"ip_allowlist"`
	TrustedProxies    []string      `yaml:"trusted_proxies"`
	LoginMaxAttempts  int           `yaml:"login_max_attempts"`
	LoginLockout      time.Duration `yaml:"login_lockout"`
}

func Load(path string) (*Config, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("read config: %w", err)
	}
	cfg := Default()
	if err := yaml.Unmarshal(data, cfg); err != nil {
		return nil, fmt.Errorf("parse config: %w", err)
	}
	resolveEnv(cfg)
	return cfg, nil
}

func Default() *Config {
	return &Config{
		Server: ServerConfig{Addr: ":8080"},
		Database: DatabaseConfig{
			Path: "./data/luminary.db",
		},
		Admin: AdminConfig{
			Username: "admin",
			Password: "admin123",
		},
		Cache: CacheConfig{
			UsageFlushInterval: 5 * time.Second,
		},
		HealthCheck: HealthCheckConfig{
			Interval: 30 * time.Second,
		},
		Security: SecurityConfig{
			EncryptionKey:    "change-me-in-production-32bytes!!",
			SessionTTL:       24 * time.Hour,
			LoginMaxAttempts: 5,
			LoginLockout:     15 * time.Minute,
		},
		Gateway: GatewayConfig{
			MaxRetries:     3,
			RetryBackoffMs: 200,
		},
	}
}

func resolveEnv(cfg *Config) {
	cfg.Admin.Username = resolveEnvValue(cfg.Admin.Username)
	cfg.Admin.Password = resolveEnvValue(cfg.Admin.Password)
	cfg.Security.EncryptionKey = resolveEnvValue(cfg.Security.EncryptionKey)
}

func resolveEnvValue(v string) string {
	if strings.HasPrefix(v, "env.") {
		key := strings.TrimPrefix(v, "env.")
		if val := os.Getenv(key); val != "" {
			return val
		}
	}
	return v
}