package config

import (
	"io"
	"os"
	"path/filepath"
	"strings"

	"gopkg.in/yaml.v3"
)

type DB struct {
	Host     string `yaml:"host"`
	Port     string `yaml:"port"`
	User     string `yaml:"user"`
	Password string `yaml:"password"`
	Name     string `yaml:"name"`
}

type App struct {
	Port        string `yaml:"port"`
	MarketingDB DB     `yaml:"marketing_db"`
	YMTDB       DB     `yaml:"ymt_db"`
}

type root struct {
	App App `yaml:"app"`
}

func Load() App {
	env := strings.ToLower(strings.TrimSpace(os.Getenv("APP_ENV")))
	paths := []string{}
	if env != "" {
		paths = append(paths,
			"config."+env+".yaml",
			filepath.Join("server", "config."+env+".yaml"),
		)
	}
	// no global fallback to config.yaml; rely on APP_ENV or environment variables
	var cfg App
	for _, p := range paths {
		if readYAML(p, &cfg) {
			break
		}
	}
	LoadEnv()
	if v := os.Getenv("MARKETING_DB_HOST"); v != "" {
		cfg.MarketingDB.Host = v
	}
	if v := os.Getenv("MARKETING_DB_PORT"); v != "" {
		cfg.MarketingDB.Port = v
	}
	if v := os.Getenv("MARKETING_DB_USER"); v != "" {
		cfg.MarketingDB.User = v
	}
	if v := os.Getenv("MARKETING_DB_PASSWORD"); v != "" {
		cfg.MarketingDB.Password = v
	}
	if v := os.Getenv("MARKETING_DB_NAME"); v != "" {
		cfg.MarketingDB.Name = v
	}
	if v := os.Getenv("YMT_DB_HOST"); v != "" {
		cfg.YMTDB.Host = v
	}
	if v := os.Getenv("YMT_DB_PORT"); v != "" {
		cfg.YMTDB.Port = v
	}
	if v := os.Getenv("YMT_DB_USER"); v != "" {
		cfg.YMTDB.User = v
	}
	if v := os.Getenv("YMT_DB_PASSWORD"); v != "" {
		cfg.YMTDB.Password = v
	}
	if v := os.Getenv("YMT_DB_NAME"); v != "" {
		cfg.YMTDB.Name = v
	}
	return cfg
}

func readYAML(path string, out *App) bool {
	f, err := os.Open(path)
	if err != nil {
		return false
	}
	defer f.Close()
	b, err := io.ReadAll(f)
	if err != nil {
		return false
	}
	var r root
	if err := yaml.Unmarshal(b, &r); err == nil {
		if r.App.Port != "" || r.App.MarketingDB.Host != "" || r.App.YMTDB.Host != "" {
			*out = r.App
			return true
		}
	}
	if err := yaml.Unmarshal(b, out); err != nil {
		return false
	}
	return true
}

func (d DB) DSN() string {
	if strings.TrimSpace(d.User) == "" || strings.TrimSpace(d.Host) == "" || strings.TrimSpace(d.Port) == "" || strings.TrimSpace(d.Name) == "" {
		return ""
	}
	return d.User + ":" + d.Password + "@tcp(" + d.Host + ":" + d.Port + ")/" + d.Name + "?parseTime=True&loc=Local&charset=utf8mb4"
}

func LoadEnv() {
	env := strings.ToLower(strings.TrimSpace(os.Getenv("APP_ENV")))
	paths := []string{}
	if env != "" {
		paths = append(paths,
			".env."+env,
			filepath.Join("server", ".env."+env),
		)
	}
	paths = append(paths,
		".env.local",
		filepath.Join("server", ".env.local"),
	)
	for _, p := range paths {
		f, err := os.Open(p)
		if err != nil {
			continue
		}
		b, err := io.ReadAll(f)
		f.Close()
		if err != nil {
			continue
		}
		lines := strings.Split(string(b), "\n")
		for _, ln := range lines {
			s := strings.TrimSpace(ln)
			if s == "" || strings.HasPrefix(s, "#") {
				continue
			}
			kv := strings.SplitN(s, "=", 2)
			if len(kv) != 2 {
				continue
			}
			k := strings.TrimSpace(kv[0])
			v := strings.TrimSpace(kv[1])
			if k != "" {
				os.Setenv(k, v)
			}
		}
		break
	}
}