/*
   GoToSocial
   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU Affero 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 Affero General Public License for more details.

   You should have received a copy of the GNU Affero General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

package main

import (
	"flag"
	"fmt"
	"io"
	"os"
	"os/exec"
	"reflect"
	"strings"
	"time"

	"codeberg.org/gruf/go-bytesize"
)

const license = `/*
   GoToSocial
   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU Affero 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 Affero General Public License for more details.

   You should have received a copy of the GNU Affero General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/
`

type Configuration struct {
	LogLevel        string   `name:"log-level" usage:"Log level to run at: [trace, debug, info, warn, fatal]"`
	LogDbQueries    bool     `name:"log-db-queries" usage:"Log database queries verbosely when log-level is trace or debug"`
	ApplicationName string   `name:"application-name" usage:"Name of the application, used in various places internally"`
	LandingPageUser string   `name:"landing-page-user" usage:"the user that should be shown on the instance's landing page"`
	ConfigPath      string   `name:"config-path" usage:"Path to a file containing gotosocial configuration. Values set in this file will be overwritten by values set as env vars or arguments"`
	Host            string   `name:"host" usage:"Hostname to use for the server (eg., example.org, gotosocial.whatever.com). DO NOT change this on a server that's already run!"`
	AccountDomain   string   `name:"account-domain" usage:"Domain to use in account names (eg., example.org, whatever.com). If not set, will default to the setting for host. DO NOT change this on a server that's already run!"`
	Protocol        string   `name:"protocol" usage:"Protocol to use for the REST api of the server (only use http if you are debugging or behind a reverse proxy!)"`
	BindAddress     string   `name:"bind-address" usage:"Bind address to use for the GoToSocial server (eg., 0.0.0.0, 172.138.0.9, [::], localhost). For ipv6, enclose the address in square brackets, eg [2001:db8::fed1]. Default binds to all interfaces."`
	Port            int      `name:"port" usage:"Port to use for GoToSocial. Change this to 443 if you're running the binary directly on the host machine."`
	TrustedProxies  []string `name:"trusted-proxies" usage:"Proxies to trust when parsing x-forwarded headers into real IPs."`
	SoftwareVersion string   `name:"software-version" usage:""`

	DbType      string `name:"db-type" usage:"Database type: eg., postgres"`
	DbAddress   string `name:"db-address" usage:"Database ipv4 address, hostname, or filename"`
	DbPort      int    `name:"db-port" usage:"Database port"`
	DbUser      string `name:"db-user" usage:"Database username"`
	DbPassword  string `name:"db-password" usage:"Database password"`
	DbDatabase  string `name:"db-database" usage:"Database name"`
	DbTLSMode   string `name:"db-tls-mode" usage:"Database tls mode"`
	DbTLSCACert string `name:"db-tls-ca-cert" usage:"Path to CA cert for db tls connection"`

	WebTemplateBaseDir string `name:"web-template-base-dir" usage:"Basedir for html templating files for rendering pages and composing emails."`
	WebAssetBaseDir    string `name:"web-asset-base-dir" usage:"Directory to serve static assets from, accessible at example.org/assets/"`

	InstanceExposePeers            bool `name:"instance-expose-peers" usage:"Allow unauthenticated users to query /api/v1/instance/peers?filter=open"`
	InstanceExposeSuspended        bool `name:"instance-expose-suspended" usage:"Expose suspended instances via web UI, and allow unauthenticated users to query /api/v1/instance/peers?filter=suspended"`
	InstanceExposePublicTimeline   bool `name:"instance-expose-public-timeline" usage:"Allow unauthenticated users to query /api/v1/timelines/public"`
	InstanceDeliverToSharedInboxes bool `name:"instance-deliver-to-shared-inboxes" usage:"Deliver federated messages to shared inboxes, if they're available."`

	AccountsRegistrationOpen bool `name:"accounts-registration-open" usage:"Allow anyone to submit an account signup request. If false, server will be invite-only."`
	AccountsApprovalRequired bool `name:"accounts-approval-required" usage:"Do account signups require approval by an admin or moderator before user can log in? If false, new registrations will be automatically approved."`
	AccountsReasonRequired   bool `name:"accounts-reason-required" usage:"Do new account signups require a reason to be submitted on registration?"`
	AccountsAllowCustomCSS   bool `name:"accounts-allow-custom-css" usage:"Allow accounts to enable custom CSS for their profile pages and statuses."`

	MediaImageMaxSize        bytesize.Size `name:"media-image-max-size" usage:"Max size of accepted images in bytes"`
	MediaVideoMaxSize        bytesize.Size `name:"media-video-max-size" usage:"Max size of accepted videos in bytes"`
	MediaDescriptionMinChars int           `name:"media-description-min-chars" usage:"Min required chars for an image description"`
	MediaDescriptionMaxChars int           `name:"media-description-max-chars" usage:"Max permitted chars for an image description"`
	MediaRemoteCacheDays     int           `name:"media-remote-cache-days" usage:"Number of days to locally cache media from remote instances. If set to 0, remote media will be kept indefinitely."`
	MediaEmojiLocalMaxSize   bytesize.Size `name:"media-emoji-local-max-size" usage:"Max size in bytes of emojis uploaded to this instance via the admin API."`
	MediaEmojiRemoteMaxSize  bytesize.Size `name:"media-emoji-remote-max-size" usage:"Max size in bytes of emojis to download from other instances."`

	StorageBackend       string `name:"storage-backend" usage:"Storage backend to use for media attachments"`
	StorageLocalBasePath string `name:"storage-local-base-path" usage:"Full path to an already-created directory where gts should store/retrieve media files. Subfolders will be created within this dir."`
	StorageS3Endpoint    string `name:"storage-s3-endpoint" usage:"S3 Endpoint URL (e.g 'minio.example.org:9000')"`
	StorageS3AccessKey   string `name:"storage-s3-access-key" usage:"S3 Access Key"`
	StorageS3SecretKey   string `name:"storage-s3-secret-key" usage:"S3 Secret Key"`
	StorageS3UseSSL      bool   `name:"storage-s3-use-ssl" usage:"Use SSL for S3 connections. Only set this to 'false' when testing locally"`
	StorageS3BucketName  string `name:"storage-s3-bucket" usage:"Place blobs in this bucket"`
	StorageS3Proxy       bool   `name:"storage-s3-proxy" usage:"Proxy S3 contents through GoToSocial instead of redirecting to a presigned URL"`

	StatusesMaxChars           int `name:"statuses-max-chars" usage:"Max permitted characters for posted statuses"`
	StatusesCWMaxChars         int `name:"statuses-cw-max-chars" usage:"Max permitted characters for content/spoiler warnings on statuses"`
	StatusesPollMaxOptions     int `name:"statuses-poll-max-options" usage:"Max amount of options permitted on a poll"`
	StatusesPollOptionMaxChars int `name:"statuses-poll-option-max-chars" usage:"Max amount of characters for a poll option"`
	StatusesMediaMaxFiles      int `name:"statuses-media-max-files" usage:"Maximum number of media files/attachments per status"`

	LetsEncryptEnabled      bool   `name:"letsencrypt-enabled" usage:"Enable letsencrypt TLS certs for this server. If set to true, then cert dir also needs to be set (or take the default)."`
	LetsEncryptPort         int    `name:"letsencrypt-port" usage:"Port to listen on for letsencrypt certificate challenges. Must not be the same as the GtS webserver/API port."`
	LetsEncryptCertDir      string `name:"letsencrypt-cert-dir" usage:"Directory to store acquired letsencrypt certificates."`
	LetsEncryptEmailAddress string `name:"letsencrypt-email-address" usage:"Email address to use when requesting letsencrypt certs. Will receive updates on cert expiry etc."`

	OIDCEnabled          bool     `name:"oidc-enabled" usage:"Enabled OIDC authorization for this instance. If set to true, then the other OIDC flags must also be set."`
	OIDCIdpName          string   `name:"oidc-idp-name" usage:"Name of the OIDC identity provider. Will be shown to the user when logging in."`
	OIDCSkipVerification bool     `name:"oidc-skip-verification" usage:"Skip verification of tokens returned by the OIDC provider. Should only be set to 'true' for testing purposes, never in a production environment!"`
	OIDCIssuer           string   `name:"oidc-issuer" usage:"Address of the OIDC issuer. Should be the web address, including protocol, at which the issuer can be reached. Eg., 'https://example.org/auth'"`
	OIDCClientID         string   `name:"oidc-client-id" usage:"ClientID of GoToSocial, as registered with the OIDC provider."`
	OIDCClientSecret     string   `name:"oidc-client-secret" usage:"ClientSecret of GoToSocial, as registered with the OIDC provider."`
	OIDCScopes           []string `name:"oidc-scopes" usage:"OIDC scopes."`
	OIDCLinkExisting     bool     `name:"oidc-link-existing" usage:"link existing user accounts to OIDC logins based on the stored email value"`

	SMTPHost     string `name:"smtp-host" usage:"Host of the smtp server. Eg., 'smtp.eu.mailgun.org'"`
	SMTPPort     int    `name:"smtp-port" usage:"Port of the smtp server. Eg., 587"`
	SMTPUsername string `name:"smtp-username" usage:"Username to authenticate with the smtp server as. Eg., 'postmaster@mail.example.org'"`
	SMTPPassword string `name:"smtp-password" usage:"Password to pass to the smtp server."`
	SMTPFrom     string `name:"smtp-from" usage:"Address to use as the 'from' field of the email. Eg., 'gotosocial@example.org'"`

	SyslogEnabled  bool   `name:"syslog-enabled" usage:"Enable the syslog logging hook. Logs will be mirrored to the configured destination."`
	SyslogProtocol string `name:"syslog-protocol" usage:"Protocol to use when directing logs to syslog. Leave empty to connect to local syslog."`
	SyslogAddress  string `name:"syslog-address" usage:"Address:port to send syslog logs to. Leave empty to connect to local syslog."`

	AdvancedCookiesSamesite   string `name:"advanced-cookies-samesite" usage:"'strict' or 'lax', see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Set-Cookie/SameSite"`
	AdvancedRateLimitRequests int    `name:"advanced-rate-limit-requests" usage:"Amount of HTTP requests to permit within a 5 minute window. 0 or less turns rate limiting off."`

	// Cache configuration vars.
	Cache CacheConfiguration `name:"cache"`

	// TODO: move these elsewhere, these are more ephemeral vs long-running flags like above
	AdminAccountUsername  string `name:"username" usage:"the username to create/delete/etc"`
	AdminAccountEmail     string `name:"email" usage:"the email address of this account"`
	AdminAccountPassword  string `name:"password" usage:"the password to set for this account"`
	AdminTransPath        string `name:"path" usage:"the path of the file to import from/export to"`
	AdminMediaPruneDryRun bool   `name:"dry-run" usage:"perform a dry run and only log number of items eligible for pruning"`
}

type CacheConfiguration struct {
	GTS GTSCacheConfiguration `name:"gts"`
}

type GTSCacheConfiguration struct {
	AccountMaxSize   int           `name:"account-max-size"`
	AccountTTL       time.Duration `name:"account-ttl"`
	AccountSweepFreq time.Duration `name:"account-sweep-freq"`

	BlockMaxSize   int           `name:"block-max-size"`
	BlockTTL       time.Duration `name:"block-ttl"`
	BlockSweepFreq time.Duration `name:"block-sweep-freq"`

	DomainBlockMaxSize   int           `name:"domain-block-max-size"`
	DomainBlockTTL       time.Duration `name:"domain-block-ttl"`
	DomainBlockSweepFreq time.Duration `name:"domain-block-sweep-freq"`

	EmojiMaxSize   int           `name:"emoji-max-size"`
	EmojiTTL       time.Duration `name:"emoji-ttl"`
	EmojiSweepFreq time.Duration `name:"emoji-sweep-freq"`

	EmojiCategoryMaxSize   int           `name:"emoji-category-max-size"`
	EmojiCategoryTTL       time.Duration `name:"emoji-category-ttl"`
	EmojiCategorySweepFreq time.Duration `name:"emoji-category-sweep-freq"`

	MentionMaxSize   int           `name:"mention-max-size"`
	MentionTTL       time.Duration `name:"mention-ttl"`
	MentionSweepFreq time.Duration `name:"mention-sweep-freq"`

	NotificationMaxSize   int           `name:"notification-max-size"`
	NotificationTTL       time.Duration `name:"notification-ttl"`
	NotificationSweepFreq time.Duration `name:"notification-sweep-freq"`

	StatusMaxSize   int           `name:"status-max-size"`
	StatusTTL       time.Duration `name:"status-ttl"`
	StatusSweepFreq time.Duration `name:"status-sweep-freq"`

	TombstoneMaxSize   int           `name:"tombstone-max-size"`
	TombstoneTTL       time.Duration `name:"tombstone-ttl"`
	TombstoneSweepFreq time.Duration `name:"tombstone-sweep-freq"`

	UserMaxSize   int           `name:"user-max-size"`
	UserTTL       time.Duration `name:"user-ttl"`
	UserSweepFreq time.Duration `name:"user-sweep-freq"`
}

func main() {
	var out string

	// Load runtime config flags
	flag.StringVar(&out, "out", "", "Generated file output path")
	flag.Parse()

	// Open output file path
	output, err := os.OpenFile(out, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0o644)
	if err != nil {
		panic(err)
	}

	fmt.Fprint(output, "// THIS IS A GENERATED FILE, DO NOT EDIT BY HAND\n")
	fmt.Fprint(output, license)
	fmt.Fprint(output, "package config\n\n")
	fmt.Fprint(output, "import \"codeberg.org/gruf/go-bytesize\"\n\n")
	generateFields(output, nil, reflect.TypeOf(Configuration{}))
	_ = output.Close()
	_ = exec.Command("gofumports", "-w", out).Run()

	// The plan here is that eventually we might be able
	// to generate an example configuration from struct tags
}

func generateFields(output io.Writer, prefixes []string, t reflect.Type) {
	for i := 0; i < t.NumField(); i++ {
		field := t.Field(i)

		if ft := field.Type; ft.Kind() == reflect.Struct {
			// This is a struct field containing further nested config vars.
			generateFields(output, append(prefixes, field.Name), ft)
			continue
		}

		// Get prefixed config variable name
		name := strings.Join(prefixes, "") + field.Name

		// Get period-separated (if nested) config variable "path"
		fieldPath := strings.Join(append(prefixes, field.Name), ".")

		// Get dash-separated config variable CLI flag "path"
		flagPath := strings.Join(append(prefixes, field.Tag.Get("name")), "-")
		flagPath = strings.ToLower(flagPath)

		// ConfigState structure helper methods
		fmt.Fprintf(output, "// Get%s safely fetches the Configuration value for state's '%s' field\n", name, fieldPath)
		fmt.Fprintf(output, "func (st *ConfigState) Get%s() (v %s) {\n", name, field.Type.String())
		fmt.Fprintf(output, "\tst.mutex.Lock()\n")
		fmt.Fprintf(output, "\tv = st.config.%s\n", fieldPath)
		fmt.Fprintf(output, "\tst.mutex.Unlock()\n")
		fmt.Fprintf(output, "\treturn\n")
		fmt.Fprintf(output, "}\n\n")
		fmt.Fprintf(output, "// Set%s safely sets the Configuration value for state's '%s' field\n", name, fieldPath)
		fmt.Fprintf(output, "func (st *ConfigState) Set%s(v %s) {\n", name, field.Type.String())
		fmt.Fprintf(output, "\tst.mutex.Lock()\n")
		fmt.Fprintf(output, "\tdefer st.mutex.Unlock()\n")
		fmt.Fprintf(output, "\tst.config.%s = v\n", fieldPath)
		fmt.Fprintf(output, "\tst.reloadToViper()\n")
		fmt.Fprintf(output, "}\n\n")

		// Global ConfigState helper methods
		// TODO: remove when we pass around a ConfigState{}
		fmt.Fprintf(output, "// %sFlag returns the flag name for the '%s' field\n", name, fieldPath)
		fmt.Fprintf(output, "func %sFlag() string { return \"%s\" }\n\n", name, flagPath)
		fmt.Fprintf(output, "// Get%s safely fetches the value for global configuration '%s' field\n", name, fieldPath)
		fmt.Fprintf(output, "func Get%[1]s() %[2]s { return global.Get%[1]s() }\n\n", name, field.Type.String())
		fmt.Fprintf(output, "// Set%s safely sets the value for global configuration '%s' field\n", name, fieldPath)
		fmt.Fprintf(output, "func Set%[1]s(v %[2]s) { global.Set%[1]s(v) }\n\n", name, field.Type.String())
	}
}