package config

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

	"github.com/spf13/viper"
)

const (
	// TemplateExt stores the extension used for the template files
	TemplateExt = ".gohtml"

	// StaticDir stores the name of the directory that will serve static files
	StaticDir = "static"

	// StaticPrefix stores the URL prefix used when serving static files
	StaticPrefix = "files"
)

type environment string

const (
	// EnvLocal represents the local environment
	EnvLocal environment = "local"

	// EnvTest represents the test environment
	EnvTest environment = "test"

	// EnvDevelop represents the development environment
	EnvDevelop environment = "dev"

	// EnvStaging represents the staging environment
	EnvStaging environment = "staging"

	// EnvQA represents the qa environment
	EnvQA environment = "qa"

	// EnvProduction represents the production environment
	EnvProduction environment = "prod"
)

// SwitchEnvironment sets the environment variable used to dictate which environment the application is
// currently running in.
// This must be called prior to loading the configuration in order for it to take effect.
func SwitchEnvironment(env environment) {
	if err := os.Setenv("PAGODA_APP_ENVIRONMENT", string(env)); err != nil {
		panic(err)
	}
}

type (
	// Config stores complete configuration
	Config struct {
		HTTP    HTTPConfig
		App     AppConfig
		Cache   CacheConfig
		Storage StorageConfig
		Tasks   TasksConfig
		Mail    MailConfig
	}

	// HTTPConfig stores HTTP configuration
	HTTPConfig struct {
		Hostname     string
		Port         uint16
		ReadTimeout  time.Duration
		WriteTimeout time.Duration
		IdleTimeout  time.Duration
		TLS          struct {
			Enabled     bool
			Certificate string
			Key         string
		}
	}

	// AppConfig stores application configuration
	AppConfig struct {
		Name          string
		Environment   environment
		EncryptionKey string
		Timeout       time.Duration
		PasswordToken struct {
			Expiration time.Duration
			Length     int
		}
		EmailVerificationTokenExpiration time.Duration
	}

	// CacheConfig stores the cache configuration
	CacheConfig struct {
		Capacity   int
		Expiration struct {
			StaticFile time.Duration
			Page       time.Duration
		}
	}

	// StorageConfig stores the storage configuration
	StorageConfig struct {
		// DatabaseFile is the path used to find the database file.
		// It can be an absolute path, or a path relative to the config file location.
		DatabaseFile string

		// MigrationsDir is the path used to find the migration files.
		// It can be an absolute path, or a path relative to the config file location.
		MigrationsDir string
	}

	// TasksConfig stores the tasks configuration
	TasksConfig struct {
		Goroutines      int
		ReleaseAfter    time.Duration
		CleanupInterval time.Duration
	}

	// MailConfig stores the mail configuration
	MailConfig struct {
		Hostname    string
		Port        uint16
		User        string
		Password    string
		FromAddress string
	}
)

// GetConfig loads and returns configuration
func GetConfig() (Config, error) {
	var c Config

	// Load the config file
	viper.SetConfigName("config")
	viper.SetConfigType("yaml")
	viper.AddConfigPath(".")
	viper.AddConfigPath("config")
	viper.AddConfigPath("../")
	viper.AddConfigPath("../../")

	// Load env variables
	viper.SetEnvPrefix("pagoda")
	viper.AutomaticEnv()
	viper.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))

	if err := viper.ReadInConfig(); err != nil {
		return c, err
	}

	if err := viper.Unmarshal(&c); err != nil {
		return c, err
	}

	usedConfigFilePath := viper.GetViper().ConfigFileUsed()

	configFileDir := filepath.Dir(usedConfigFilePath)
	if !filepath.IsAbs(c.Storage.DatabaseFile) {
		c.Storage.DatabaseFile = filepath.Join(configFileDir, c.Storage.DatabaseFile)
	}
	if !filepath.IsAbs(c.Storage.MigrationsDir) {
		c.Storage.MigrationsDir = filepath.Join(configFileDir, c.Storage.MigrationsDir)
	}

	return c, nil
}