// Copyright 2017 Frédéric Guillot. All rights reserved.
// Use of this source code is governed by the Apache 2.0
// license that can be found in the LICENSE file.

package config

import (
	"net/url"
	"os"
	"strconv"

	"github.com/miniflux/miniflux/logger"
)

const (
	defaultBaseURL                 = "http://localhost"
	defaultDatabaseURL             = "postgres://postgres:postgres@localhost/miniflux2?sslmode=disable"
	defaultWorkerPoolSize          = 5
	defaultPollingFrequency        = 60
	defaultBatchSize               = 10
	defaultDatabaseMaxConns        = 20
	defaultListenAddr              = "127.0.0.1:8080"
	defaultCertFile                = ""
	defaultKeyFile                 = ""
	defaultCertDomain              = ""
	defaultCertCache               = "/tmp/cert_cache"
	defaultSessionCleanupFrequency = 24
)

// Config manages configuration parameters.
type Config struct {
	IsHTTPS  bool
	baseURL  string
	rootURL  string
	basePath string
}

func (c *Config) get(key, fallback string) string {
	value := os.Getenv(key)
	if value == "" {
		return fallback
	}

	return value
}

func (c *Config) getInt(key string, fallback int) int {
	value := os.Getenv(key)
	if value == "" {
		return fallback
	}

	v, _ := strconv.Atoi(value)
	return v
}

// HasDebugMode returns true if debug mode is enabled.
func (c *Config) HasDebugMode() bool {
	return c.get("DEBUG", "") != ""
}

// BaseURL returns the application base URL with path.
func (c *Config) BaseURL() string {
	if c.baseURL == "" {
		c.baseURL = c.get("BASE_URL", defaultBaseURL)
		if c.baseURL[len(c.baseURL)-1:] == "/" {
			c.baseURL = c.baseURL[:len(c.baseURL)-1]
		}
	}
	return c.baseURL
}

// RootURL returns the base URL without path.
func (c *Config) RootURL() string {
	if c.rootURL == "" {
		u, _ := url.Parse(c.BaseURL())
		u.Path = ""
		c.rootURL = u.String()
	}
	return c.rootURL
}

// BasePath returns the application base path according to the base URL.
func (c *Config) BasePath() string {
	if c.basePath == "" {
		u, _ := url.Parse(c.BaseURL())
		c.basePath = u.Path
	}
	return c.basePath
}

// DatabaseURL returns the database URL.
func (c *Config) DatabaseURL() string {
	value, exists := os.LookupEnv("DATABASE_URL")
	if !exists {
		logger.Info("The environment variable DATABASE_URL is not configured (the default value is used instead)")
	}

	if value == "" {
		value = defaultDatabaseURL
	}

	return value
}

// DatabaseMaxConnections returns the number of maximum database connections.
func (c *Config) DatabaseMaxConnections() int {
	return c.getInt("DATABASE_MAX_CONNS", defaultDatabaseMaxConns)
}

// ListenAddr returns the listen address for the HTTP server.
func (c *Config) ListenAddr() string {
	return c.get("LISTEN_ADDR", defaultListenAddr)
}

// CertFile returns the SSL certificate filename if any.
func (c *Config) CertFile() string {
	return c.get("CERT_FILE", defaultCertFile)
}

// KeyFile returns the private key filename for custom SSL certificate.
func (c *Config) KeyFile() string {
	return c.get("KEY_FILE", defaultKeyFile)
}

// CertDomain returns the domain to use for Let's Encrypt certificate.
func (c *Config) CertDomain() string {
	return c.get("CERT_DOMAIN", defaultCertDomain)
}

// CertCache returns the directory to use for Let's Encrypt session cache.
func (c *Config) CertCache() string {
	return c.get("CERT_CACHE", defaultCertCache)
}

// SessionCleanupFrequency returns the interval for session cleanup.
func (c *Config) SessionCleanupFrequency() int {
	return c.getInt("SESSION_CLEANUP_FREQUENCY", defaultSessionCleanupFrequency)
}

// WorkerPoolSize returns the number of background worker.
func (c *Config) WorkerPoolSize() int {
	return c.getInt("WORKER_POOL_SIZE", defaultWorkerPoolSize)
}

// PollingFrequency returns the interval to refresh feeds in the background.
func (c *Config) PollingFrequency() int {
	return c.getInt("POLLING_FREQUENCY", defaultPollingFrequency)
}

// BatchSize returns the number of feeds to send for background processing.
func (c *Config) BatchSize() int {
	return c.getInt("BATCH_SIZE", defaultBatchSize)
}

// IsOAuth2UserCreationAllowed returns true if user creation is allowed for OAuth2 users.
func (c *Config) IsOAuth2UserCreationAllowed() bool {
	return c.getInt("OAUTH2_USER_CREATION", 0) == 1
}

// OAuth2ClientID returns the OAuth2 Client ID.
func (c *Config) OAuth2ClientID() string {
	return c.get("OAUTH2_CLIENT_ID", "")
}

// OAuth2ClientSecret returns the OAuth2 client secret.
func (c *Config) OAuth2ClientSecret() string {
	return c.get("OAUTH2_CLIENT_SECRET", "")
}

// OAuth2RedirectURL returns the OAuth2 redirect URL.
func (c *Config) OAuth2RedirectURL() string {
	return c.get("OAUTH2_REDIRECT_URL", "")
}

// OAuth2Provider returns the name of the OAuth2 provider configured.
func (c *Config) OAuth2Provider() string {
	return c.get("OAUTH2_PROVIDER", "")
}

// HasHSTS returns true if HTTP Strict Transport Security is enabled.
func (c *Config) HasHSTS() bool {
	return c.get("DISABLE_HSTS", "") == ""
}

// NewConfig returns a new Config.
func NewConfig() *Config {
	return &Config{IsHTTPS: os.Getenv("HTTPS") != ""}
}