// Package config reads application settings from the environment.
package config

import (
	"fmt"
	"os"
	"strconv"
	"strings"
)

type Config struct {
	Addr        string // listen address, e.g. ":8080"
	BaseDomain  string // e.g. "example.com" (no port)
	PublicPort  string // port to append to generated blog URLs ("" in prod behind a proxy)
	DatabaseURL string
	JWTSecret   []byte
	// Bootstrap superadmin created on first start if no superadmin exists.
	SuperadminUsername string
	SuperadminPassword string
	MaxUploadBytes     int64 // default per-file limit; the superadmin can override it per blog
	Dev                bool  // reload templates/static from disk
}

func Load() (*Config, error) {
	c := &Config{
		Addr:               env("ADDR", ":8080"),
		BaseDomain:         strings.ToLower(strings.TrimSpace(env("BASE_DOMAIN", "blogspace.localhost"))),
		PublicPort:         env("PUBLIC_PORT", ""),
		DatabaseURL:        env("DATABASE_URL", "postgres://blogspace:blogspace@localhost:5432/blogspace?sslmode=disable"),
		JWTSecret:          []byte(env("JWT_SECRET", "")),
		SuperadminUsername: env("SUPERADMIN_USERNAME", "admin"),
		SuperadminPassword: env("SUPERADMIN_PASSWORD", ""),
		Dev:                envBool("DEV", false),
	}
	mb, err := strconv.Atoi(env("MAX_UPLOAD_MB", "10"))
	if err != nil || mb <= 0 {
		return nil, fmt.Errorf("MAX_UPLOAD_MB must be a positive integer")
	}
	c.MaxUploadBytes = int64(mb) << 20

	if len(c.JWTSecret) == 0 {
		if !c.Dev {
			return nil, fmt.Errorf("JWT_SECRET must be set")
		}
		c.JWTSecret = []byte("dev-insecure-secret-change-me")
	}
	if len(c.JWTSecret) < 16 && !c.Dev {
		return nil, fmt.Errorf("JWT_SECRET must be at least 16 bytes")
	}
	if c.BaseDomain == "" {
		return nil, fmt.Errorf("BASE_DOMAIN must be set")
	}
	return c, nil
}

// RootSubdomain is the pseudo-subdomain of the blog served on the base domain
// itself (and on www.). It is owned by the superadmin.
const RootSubdomain = "www"

// BlogURL returns the public URL for a blog subdomain.
func (c *Config) BlogURL(sub string) string {
	if sub == RootSubdomain {
		return c.RootURL()
	}
	return "http://" + sub + "." + c.HostWithPort()
}

// RootURL returns the public URL of the management site.
func (c *Config) RootURL() string {
	return "http://" + c.HostWithPort()
}

func (c *Config) HostWithPort() string {
	if c.PublicPort != "" {
		return c.BaseDomain + ":" + c.PublicPort
	}
	return c.BaseDomain
}

func env(key, def string) string {
	if v, ok := os.LookupEnv(key); ok {
		return v
	}
	return def
}

func envBool(key string, def bool) bool {
	v, ok := os.LookupEnv(key)
	if !ok {
		return def
	}
	switch strings.ToLower(v) {
	case "1", "true", "yes", "on":
		return true
	}
	return false
}