// Copyright (C) 2019 Nicola Murino
//
// 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, version 3.
//
// 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 <https://www.gnu.org/licenses/>.

package plugin

import (
	"fmt"
	"slices"
	"sync"
	"time"

	"github.com/hashicorp/go-hclog"
	"github.com/hashicorp/go-plugin"
	"github.com/sftpgo/sdk/plugin/notifier"

	"github.com/drakkan/sftpgo/v2/internal/logger"
)

// NotifierConfig defines configuration parameters for notifiers plugins
type NotifierConfig struct {
	FsEvents          []string `json:"fs_events" mapstructure:"fs_events"`
	ProviderEvents    []string `json:"provider_events" mapstructure:"provider_events"`
	ProviderObjects   []string `json:"provider_objects" mapstructure:"provider_objects"`
	LogEvents         []int    `json:"log_events" mapstructure:"log_events"`
	RetryMaxTime      int      `json:"retry_max_time" mapstructure:"retry_max_time"`
	RetryQueueMaxSize int      `json:"retry_queue_max_size" mapstructure:"retry_queue_max_size"`
}

func (c *NotifierConfig) hasActions() bool {
	if len(c.FsEvents) > 0 {
		return true
	}
	if len(c.ProviderEvents) > 0 && len(c.ProviderObjects) > 0 {
		return true
	}
	if len(c.LogEvents) > 0 {
		return true
	}
	return false
}

type notifierPlugin struct {
	config         Config
	notifier       notifier.Notifier
	client         *plugin.Client
	mu             sync.RWMutex
	fsEvents       []*notifier.FsEvent
	providerEvents []*notifier.ProviderEvent
	logEvents      []*notifier.LogEvent
}

func newNotifierPlugin(config Config) (*notifierPlugin, error) {
	p := &notifierPlugin{
		config: config,
	}
	if err := p.initialize(); err != nil {
		logger.Warn(logSender, "", "unable to create notifier plugin: %v, config %+v", err, config)
		return nil, err
	}
	return p, nil
}

func (p *notifierPlugin) exited() bool {
	return p.client.Exited()
}

func (p *notifierPlugin) cleanup() {
	p.client.Kill()
}

func (p *notifierPlugin) initialize() error {
	killProcess(p.config.Cmd)
	logger.Debug(logSender, "", "create new notifier plugin %q", p.config.Cmd)
	if !p.config.NotifierOptions.hasActions() {
		return fmt.Errorf("no actions defined for the notifier plugin %q", p.config.Cmd)
	}
	secureConfig, err := p.config.getSecureConfig()
	if err != nil {
		return err
	}
	client := plugin.NewClient(&plugin.ClientConfig{
		HandshakeConfig: notifier.Handshake,
		Plugins:         notifier.PluginMap,
		Cmd:             p.config.getCommand(),
		SkipHostEnv:     true,
		AllowedProtocols: []plugin.Protocol{
			plugin.ProtocolGRPC,
		},
		AutoMTLS:     p.config.AutoMTLS,
		SecureConfig: secureConfig,
		Managed:      false,
		Logger: &logger.HCLogAdapter{
			Logger: hclog.New(&hclog.LoggerOptions{
				Name:        fmt.Sprintf("%s.%s", logSender, notifier.PluginName),
				Level:       pluginsLogLevel,
				DisableTime: true,
			}),
		},
	})
	rpcClient, err := client.Client()
	if err != nil {
		logger.Debug(logSender, "", "unable to get rpc client for plugin %q: %v", p.config.Cmd, err)
		return err
	}
	raw, err := rpcClient.Dispense(notifier.PluginName)
	if err != nil {
		logger.Debug(logSender, "", "unable to get plugin %v from rpc client for command %q: %v",
			notifier.PluginName, p.config.Cmd, err)
		return err
	}

	p.client = client
	p.notifier = raw.(notifier.Notifier)

	return nil
}

func (p *notifierPlugin) queueSize() int {
	p.mu.RLock()
	defer p.mu.RUnlock()

	return len(p.providerEvents) + len(p.fsEvents) + len(p.logEvents)
}

func (p *notifierPlugin) queueFsEvent(ev *notifier.FsEvent) {
	p.mu.Lock()
	defer p.mu.Unlock()

	p.fsEvents = append(p.fsEvents, ev)
}

func (p *notifierPlugin) queueProviderEvent(ev *notifier.ProviderEvent) {
	p.mu.Lock()
	defer p.mu.Unlock()

	p.providerEvents = append(p.providerEvents, ev)
}

func (p *notifierPlugin) queueLogEvent(ev *notifier.LogEvent) {
	p.mu.Lock()
	defer p.mu.Unlock()

	p.logEvents = append(p.logEvents, ev)
}

func (p *notifierPlugin) canQueueEvent(timestamp int64) bool {
	if p.config.NotifierOptions.RetryMaxTime == 0 {
		return false
	}
	if time.Now().After(time.Unix(0, timestamp).Add(time.Duration(p.config.NotifierOptions.RetryMaxTime) * time.Second)) {
		logger.Warn(logSender, "", "dropping too late event for plugin %v, event timestamp: %v",
			p.config.Cmd, time.Unix(0, timestamp))
		return false
	}
	if p.config.NotifierOptions.RetryQueueMaxSize > 0 {
		return p.queueSize() < p.config.NotifierOptions.RetryQueueMaxSize
	}
	return true
}

func (p *notifierPlugin) notifyFsAction(event *notifier.FsEvent) {
	if !slices.Contains(p.config.NotifierOptions.FsEvents, event.Action) {
		return
	}
	p.sendFsEvent(event)
}

func (p *notifierPlugin) notifyProviderAction(event *notifier.ProviderEvent, object Renderer) {
	if !slices.Contains(p.config.NotifierOptions.ProviderEvents, event.Action) ||
		!slices.Contains(p.config.NotifierOptions.ProviderObjects, event.ObjectType) {
		return
	}
	p.sendProviderEvent(event, object)
}

func (p *notifierPlugin) notifyLogEvent(event *notifier.LogEvent) {
	p.sendLogEvent(event)
}

func (p *notifierPlugin) sendFsEvent(ev *notifier.FsEvent) {
	go func(event *notifier.FsEvent) {
		Handler.addTask()
		defer Handler.removeTask()

		if err := p.notifier.NotifyFsEvent(event); err != nil {
			logger.Warn(logSender, "", "unable to send fs action notification to plugin %v: %v", p.config.Cmd, err)
			if p.canQueueEvent(event.Timestamp) {
				p.queueFsEvent(event)
			}
		}
	}(ev)
}

func (p *notifierPlugin) sendProviderEvent(ev *notifier.ProviderEvent, object Renderer) {
	go func(event *notifier.ProviderEvent) {
		Handler.addTask()
		defer Handler.removeTask()

		if object != nil {
			objectAsJSON, err := object.RenderAsJSON(event.Action != "delete")
			if err != nil {
				logger.Error(logSender, "", "unable to render user as json for action %q: %v", event.Action, err)
			} else {
				event.ObjectData = objectAsJSON
			}
		}

		if err := p.notifier.NotifyProviderEvent(event); err != nil {
			logger.Warn(logSender, "", "unable to send user action notification to plugin %v: %v", p.config.Cmd, err)
			if p.canQueueEvent(event.Timestamp) {
				p.queueProviderEvent(event)
			}
		}
	}(ev)
}

func (p *notifierPlugin) sendLogEvent(ev *notifier.LogEvent) {
	go func(event *notifier.LogEvent) {
		Handler.addTask()
		defer Handler.removeTask()

		if err := p.notifier.NotifyLogEvent(event); err != nil {
			logger.Warn(logSender, "", "unable to send log event to plugin %v: %v", p.config.Cmd, err)
			if p.canQueueEvent(event.Timestamp) {
				p.queueLogEvent(event)
			}
		}
	}(ev)
}

func (p *notifierPlugin) sendQueuedEvents() {
	queueSize := p.queueSize()
	if queueSize == 0 {
		return
	}
	p.mu.Lock()
	defer p.mu.Unlock()

	logger.Debug(logSender, "", "send queued events for notifier %q, events size: %v", p.config.Cmd, queueSize)

	for _, ev := range p.fsEvents {
		p.sendFsEvent(ev)
	}
	p.fsEvents = nil

	for _, ev := range p.providerEvents {
		p.sendProviderEvent(ev, nil)
	}
	p.providerEvents = nil

	for _, ev := range p.logEvents {
		p.sendLogEvent(ev)
	}
	p.logEvents = nil

	logger.Debug(logSender, "", "%d queued events sent for notifier %q,", queueSize, p.config.Cmd)
}