// Package config loads server configuration from environment variables,
// optionally seeded from a .env file in the working directory.
package config

import (
	"bufio"
	"fmt"
	"os"
	"strings"
)

type Config struct {
	Port            string
	PBURL           string
	PBAdminEmail    string
	PBAdminPasswd   string
	CORSOrigins     []string
	AuthSecret      string
	UsersCollection string
}

// devAuthSecret is used only when AUTH_SECRET is unset, so the server still
// runs out-of-the-box in development. Set AUTH_SECRET in production.
const devAuthSecret = "dev-insecure-secret-change-me"

// Load reads .env (if present) into the process environment, then builds a
// Config from environment variables. Required values that are missing produce
// an error so the server fails fast instead of misbehaving later.
func Load() (*Config, error) {
	loadDotEnv(".env")

	cfg := &Config{
		Port:            getenv("PORT", "8080"),
		PBURL:           strings.TrimRight(getenv("PB_URL", "http://10.2.1.10:8027"), "/"),
		PBAdminEmail:    os.Getenv("PB_ADMIN_EMAIL"),
		PBAdminPasswd:   os.Getenv("PB_ADMIN_PASSWORD"),
		CORSOrigins:     splitCSV(getenv("CORS_ORIGINS", "http://localhost:5173")),
		AuthSecret:      getenv("AUTH_SECRET", devAuthSecret),
		UsersCollection: getenv("AUTH_USERS_COLLECTION", "users"),
	}

	if cfg.PBAdminEmail == "" || cfg.PBAdminPasswd == "" {
		return nil, fmt.Errorf("PB_ADMIN_EMAIL and PB_ADMIN_PASSWORD are required")
	}
	return cfg, nil
}

// UsingDevAuthSecret reports whether the insecure development secret is in use.
func (c *Config) UsingDevAuthSecret() bool {
	return c.AuthSecret == devAuthSecret
}

func getenv(key, fallback string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return fallback
}

func splitCSV(s string) []string {
	var out []string
	for _, p := range strings.Split(s, ",") {
		if p = strings.TrimSpace(p); p != "" {
			out = append(out, p)
		}
	}
	return out
}

// loadDotEnv parses a simple KEY=VALUE file and sets any variables that are not
// already present in the environment. Lines starting with # are comments.
func loadDotEnv(path string) {
	f, err := os.Open(path)
	if err != nil {
		return // .env is optional
	}
	defer f.Close()

	sc := bufio.NewScanner(f)
	for sc.Scan() {
		line := strings.TrimSpace(sc.Text())
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		key, val, ok := strings.Cut(line, "=")
		if !ok {
			continue
		}
		key = strings.TrimSpace(key)
		val = strings.Trim(strings.TrimSpace(val), `"'`)
		if _, exists := os.LookupEnv(key); !exists {
			os.Setenv(key, val)
		}
	}
}