package config

import (
	"crypto/rand"
	"encoding/hex"
	"log"
	"os"
	"path/filepath"
	"strings"
)

type Config struct {
	Addr        string
	Driver      string // sqlite | postgres
	DSN         string
	AdminUser   string
	AdminPass   string
	SessionSec  string
	WebDist     string
	DataDir     string
	SiteURL     string
	InsecureDev bool

	// 对象存储（文件上传）。变量名与站主 .env 里的写法一致（站主已整理）：
	//   S3Api     = R2 的 S3 API 端点（https://<账户ID>.r2.cloudflarestorage.com，
	//               控制台 R2 概览可复制），上传走它 —— 公开域名收不了上传请求
	//   PublicURL = 公开访问域名（r2.dev / 绑定的自定义域名），文件直链走它
	//   AccessKey / SecretAccessKey / Bucket = R2 凭据与桶名
	// 五项齐全 → 上传走 R2、直链走 PublicURL；缺任一项回落本地磁盘
	// （DataDir/uploads），并在启动日志提示一句。
	StorageDriver      string // r2 | local
	S3Endpoint         string // env: S3Api
	R2Bucket           string
	R2AccessKey        string
	R2SecretKey        string
	UploadsPublicBase  string // env: PublicURL
}

func getenv(k, def string) string {
	if v := strings.TrimSpace(os.Getenv(k)); v != "" {
		return v
	}
	return def
}

func Load() (*Config, error) {
	root := getenv("ONE_ROOT", "")
	if root == "" {
		if wd, err := os.Getwd(); err == nil {
			root = filepath.Dir(wd) // server/ -> repo root
		} else {
			root = "."
		}
	}

	c := &Config{
		Addr:       getenv("ONE_ADDR", ":8080"),
		Driver:     strings.ToLower(getenv("ONE_DB_DRIVER", "sqlite")),
		AdminUser:  getenv("ONE_ADMIN_USER", "admin"),
		AdminPass:  getenv("ONE_ADMIN_PASSWORD", "admin"),
		SessionSec: getenv("ONE_SECRET", ""),
		WebDist:    getenv("ONE_WEB_DIST", filepath.Join(root, "frontend", "dist")),
		DataDir:    getenv("ONE_DATA_DIR", filepath.Join(root, "data")),
		SiteURL:    getenv("ONE_SITE_URL", "http://localhost:8080"),
	}

	if c.Driver == "" {
		c.Driver = "sqlite"
	}
	if c.Driver != "sqlite" && c.Driver != "postgres" && c.Driver != "postgresql" {
		return nil, &badDriver{c.Driver}
	}
	if c.Driver == "postgresql" {
		c.Driver = "postgres"
	}

	if c.DSN = getenv("ONE_DB_DSN", ""); c.DSN == "" {
		if c.Driver == "sqlite" {
			c.DSN = filepath.Join(c.DataDir, "one.db")
		} else {
			c.DSN = "postgres://localhost/one?sslmode=disable"
		}
	}

	if c.SessionSec == "" {
		b := make([]byte, 32)
		if _, err := rand.Read(b); err != nil {
			return nil, err
		}
		c.SessionSec = hex.EncodeToString(b)
	}

	c.InsecureDev = os.Getenv("ONE_ADMIN_PASSWORD") == ""

	// 对象存储：变量名按站主 .env 里整理好的来（无 ONE_ 前缀）。
	c.UploadsPublicBase = strings.TrimRight(getenv("PublicURL", ""), "/")
	c.S3Endpoint = getenv("S3Api", "")
	c.R2AccessKey = getenv("AccessKey", "")
	c.R2SecretKey = getenv("SecretAccessKey", "")
	c.R2Bucket = getenv("Bucket", "")
	if c.S3Endpoint != "" && c.R2Bucket != "" && c.R2AccessKey != "" && c.R2SecretKey != "" {
		c.StorageDriver = "r2"
	} else {
		c.StorageDriver = "local"
		// 配了一半（有凭据没端点之类）时给一句启动日志，别让站主猜。
		// 只报字段名，不报值。
		var missing []string
		if c.S3Endpoint == "" {
			missing = append(missing, "S3Api")
		}
		if c.R2Bucket == "" {
			missing = append(missing, "Bucket")
		}
		if c.R2AccessKey == "" {
			missing = append(missing, "AccessKey")
		}
		if c.R2SecretKey == "" {
			missing = append(missing, "SecretAccessKey")
		}
		if len(missing) > 0 {
			log.Printf("storage: R2 配置缺 %s，上传回落本地磁盘", strings.Join(missing, "、"))
		}
	}

	return c, nil
}

type badDriver struct{ d string }

func (e *badDriver) Error() string {
	return "unsupported ONE_DB_DRIVER: " + e.d + " (use sqlite or postgres)"
}