// Copyright (c) 2025 Nikolai Papin
// 
// This file is part of Easywish
// 
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// 
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
// the GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

package config

import (
	"fmt"
	"strings"

	"github.com/spf13/viper"
)

type Config struct {
	Hostname								string 	`mapstructure:"HOSTNAME"`
	Port										uint16 	`mapstructure:"PORT"`

	DatabaseUrl							string 	`mapstructure:"POSTGRES_URL"`
	RedisUrl								string 	`mapstructure:"REDIS_URL"`
	MinioUrl								string 	`mapstructure:"MINIO_URL"`

	JwtAlgorithm						string 	`mapstructure:"JWT_ALGORITHM"`
	JwtSecret								string 	`mapstructure:"JWT_SECRET"`
	JwtIssuer								string 	`mapstructure:"JWT_ISSUER"`
	JwtAudience							string 	`mapstructure:"JWT_AUDIENCE"`
	JwtExpAccess						int 		`mapstructure:"JWT_EXP_ACCESS"`
	JwtExpRefresh						int 		`mapstructure:"JWT_EXP_REFRESH"`

	SmtpEnabled							bool 		`mapstructure:"SMTP_ENABLED"`
	SmtpServer							string	`mapstructure:"SMTP_SERVER"`
	SmtpPort								uint16	`mapstructure:"SMTP_PORT"`
	SmtpUser								string 	`mapstructure:"SMTP_USER"`
	SmtpPassword						string	`mapstructure:"SMTP_PASSWORD"`
	SmtpFrom 								string	`mapstructure:"SMTP_FROM"`
	SmtpUseTLS							bool		`mapstructure:"SMTP_USE_TLS"`
	SmtpUseSSL							bool		`mapstructure:"SMTP_USE_SSL"`			
	SmtpTimeout							uint		`mapstructure:"SMTP_TIMEOUT"`

	PasswordMinLength 	  	int 		`mapstructure:"PASSWORD_MIN_LENGTH"`
	PasswordMaxLength 	  	int 	  `mapstructure:"PASSWORD_MIN_LENGTH"`
	PasswordCheckNumbers		bool		`mapstructure:"PASSWORD_CHECK_NUMBERS"`
	PasswordCheckCharacters	bool		`mapstructure:"PASSWORD_CHECK_CHARACTERS"`
	PasswordCheckCases   		bool		`mapstructure:"PASSWORD_CHECK_CASES"`
	PasswordCheckSymbols 		bool		`mapstructure:"PASSWORD_CHECK_SYMBOLS"`
	PasswordCheckLeaked 		bool		`mapstructure:"PASSWORD_CHECK_LEAKED"`

	Environment  						string 	`mapstructure:"ENVIRONMENT"`
}

func Load() (*Config, error) {

	viper.SetDefault("HOSTNAME", "localhost")
	viper.SetDefault("PORT", "8080")

	viper.SetDefault("JWT_ALGORITHM", "HS256")
	viper.SetDefault("JWT_SECRET", "default_jwt_secret_please_change")
	viper.SetDefault("JWT_EXP_ACCESS", 5)
	viper.SetDefault("JWT_EXP_REFRESH", 10080)
	viper.SetDefault("JWT_AUDIENCE", "easywish")
	viper.SetDefault("JWT_ISSUER", "easywish")

	viper.SetDefault("SMTP_ENABLED", false)
	viper.SetDefault("SMTP_USE_TLS", false)
	viper.SetDefault("SMTP_USE_SSL", false)
	viper.SetDefault("SMTP_FROM", "An Easywish instance")

	viper.SetDefault("PASSWORD_MIN_LENGTH", 6)
	viper.SetDefault("PASSWORD_MAX_LENGTH", 100)
	viper.SetDefault("PASSWORD_CHECK_NUMBERS", false)
	viper.SetDefault("PASSWORD_CHECK_CHARACTERS", false)
	viper.SetDefault("PASSWORD_CHECK_CASES", false)
	viper.SetDefault("PASSWORD_CHECK_SYMBOLS", false)
	viper.SetDefault("PASSWORD_CHECK_LEAKED", false)

	viper.SetDefault("ENVIRONMENT", "production")

	viper.AutomaticEnv()

	// Viper's AutomaticEnv() expects lowercase keys for unmarshalling into structs by default, 
	// while the environment variables and struct tags are in uppercase. 
	// Here's the stupidity we have to do to fix it:

	viper.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
	viper.BindEnv("HOSTNAME")
	viper.BindEnv("PORT")

	viper.BindEnv("POSTGRES_URL")
	viper.BindEnv("REDIS_URL")
	viper.BindEnv("MINIO_URL")

	viper.BindEnv("JWT_ALGORITHM")
	viper.BindEnv("JWT_SECRET")
	viper.BindEnv("JWT_ISSUER")
	viper.BindEnv("JWT_AUDIENCE")
	viper.BindEnv("JWT_EXP_ACCESS")
	viper.BindEnv("JWT_EXP_REFRESH")

	viper.BindEnv("SMTP_ENABLED")
	viper.BindEnv("SMTP_SERVER")
	viper.BindEnv("SMTP_PORT")
	viper.BindEnv("SMTP_USER")
	viper.BindEnv("SMTP_PASSWORD")
	viper.BindEnv("SMTP_FROM")
	viper.BindEnv("SMTP_USE_TLS")
	viper.BindEnv("SMTP_USE_SSL")
	viper.BindEnv("SMTP_TIMEOUT")

	viper.BindEnv("PASSWORD_MIN_LENGTH")
	viper.BindEnv("PASSWORD_MAX_LENGTH")
	viper.BindEnv("PASSWORD_CHECK_NUMBERS")
	viper.BindEnv("PASSWORD_CHECK_CHARACTERS")
	viper.BindEnv("PASSWORD_CHECK_CASES")
	viper.BindEnv("PASSWORD_CHECK_SYMBOLS")
	viper.BindEnv("PASSWORD_CHECK_LEAKED")

	viper.BindEnv("ENVIRONMENT")

	required := []string{
		"POSTGRES_URL",
		"REDIS_URL",
		"MINIO_URL",
	}
	var missing []string
	for _, key := range required {
		if !viper.IsSet(key) {
			missing = append(missing, key)
		}
	}
	if len(missing) > 0 {
		return nil, fmt.Errorf("missing required environment variables: %s", strings.Join(missing, ", "))
	}

	var cfg Config
	if err := viper.Unmarshal(&cfg); err != nil {
		return nil, fmt.Errorf("failed to unmarshal config: %w", err)
	}

	config = &cfg

	return &cfg, nil
}

func GetConfig() *Config {

	if config == nil {
		
		if _, err := Load(); err != nil {
			panic(err)
		}
	}

	return config
}

var config *Config