//
// Copyright 2019-2023 Nestybox, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

package implementations

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

	"github.com/sirupsen/logrus"

	"github.com/nestybox/sysbox-fs/domain"
)

// /proc/sys/net/unix handler
//
// Emulated resources:
//
// * /proc/sys/net/unix/max_dgram_qlen

type ProcSysNetUnix struct {
	domain.HandlerBase
}

var ProcSysNetUnix_Handler = &ProcSysNetUnix{
	domain.HandlerBase{
		Name:    "ProcSysNetUnix",
		Path:    "/proc/sys/net/unix",
		Enabled: true,
		EmuResourceMap: map[string]*domain.EmuResource{
			"max_dgram_qlen": {
				Kind:    domain.FileEmuResource,
				Mode:    os.FileMode(uint32(0644)),
				Enabled: true,
				Size:    1024,
			},
		},
	},
}

func (h *ProcSysNetUnix) Lookup(
	n domain.IOnodeIface,
	req *domain.HandlerRequest) (os.FileInfo, error) {

	var resource = n.Name()

	logrus.Debugf("Executing Lookup() for req-id: %#x, handler: %s, resource: %s",
		req.ID, h.Name, resource)

	// Return an artificial fileInfo if looked-up element matches any of the
	// emulated nodes.
	if v, ok := h.EmuResourceMap[resource]; ok {
		info := &domain.FileInfo{
			Fname:    resource,
			Fmode:    v.Mode,
			FmodTime: time.Now(),
			Fsize:    v.Size,
		}

		return info, nil
	}

	// If looked-up element hasn't been found by now, let's look into the actual
	// sys container rootfs.
	return h.Service.GetPassThroughHandler().Lookup(n, req)
}

func (h *ProcSysNetUnix) Open(
	n domain.IOnodeIface,
	req *domain.HandlerRequest) (bool, error) {

	var resource = n.Name()

	logrus.Debugf("Executing Open() for req-id: %#x, handler: %s, resource: %s",
		req.ID, h.Name, resource)

	switch resource {
	case "max_dgram_qlen":
		return false, nil
	}

	return h.Service.GetPassThroughHandler().Open(n, req)
}

func (h *ProcSysNetUnix) Read(
	n domain.IOnodeIface,
	req *domain.HandlerRequest) (int, error) {

	var resource = n.Name()

	logrus.Debugf("Executing Read() for req-id: %#x, handler: %s, resource: %s",
		req.ID, h.Name, resource)

	switch resource {
	case "max_dgram_qlen":
		return readCntrData(h, n, req)
	}

	// Refer to generic handler if no node match is found above.
	return h.Service.GetPassThroughHandler().Read(n, req)
}

func (h *ProcSysNetUnix) Write(
	n domain.IOnodeIface,
	req *domain.HandlerRequest) (int, error) {

	var resource = n.Name()

	logrus.Debugf("Executing Write() for req-id: %#x, handler: %s, resource: %s",
		req.ID, h.Name, resource)

	switch resource {
	case "max_dgram_qlen":
		return writeCntrData(h, n, req, writeMaxIntToFs)
	}

	// Refer to generic handler if no node match is found above.
	return h.Service.GetPassThroughHandler().Write(n, req)
}

func (h *ProcSysNetUnix) ReadDirAll(
	n domain.IOnodeIface,
	req *domain.HandlerRequest) ([]os.FileInfo, error) {

	var resource = n.Name()

	logrus.Debugf("Executing ReadDirAll() for req-id: %#x, handler: %s, resource: %s",
		req.ID, h.Name, resource)

	var fileEntries []os.FileInfo

	// Obtain relative path to the element being read.
	relpath, err := filepath.Rel(h.Path, n.Path())
	if err != nil {
		return nil, err
	}

	// Iterate through map of emulated components.
	for k, _ := range h.EmuResourceMap {

		if relpath == filepath.Dir(k) {
			info := &domain.FileInfo{
				Fname:    k,
				Fmode:    os.FileMode(uint32(0644)),
				FmodTime: time.Now(),
			}

			fileEntries = append(fileEntries, info)
		}
	}

	// Obtain the usual entries seen within container's namespaces and add them
	// to the emulated ones.
	usualEntries, err := h.Service.GetPassThroughHandler().ReadDirAll(n, req)
	if err == nil {
		fileEntries = append(fileEntries, usualEntries...)
	}

	fileEntries = domain.FileInfoSliceUniquify(fileEntries)

	return fileEntries, nil
}

func (h *ProcSysNetUnix) ReadLink(
	n domain.IOnodeIface,
	req *domain.HandlerRequest) (string, error) {

	logrus.Debugf("Executing ReadLink() for req-id: %#x, handler: %s, resource: %s",
		req.ID, h.Name, n.Name())

	return h.Service.GetPassThroughHandler().ReadLink(n, req)
}

func (h *ProcSysNetUnix) GetName() string {
	return h.Name
}

func (h *ProcSysNetUnix) GetPath() string {
	return h.Path
}

func (h *ProcSysNetUnix) GetService() domain.HandlerServiceIface {
	return h.Service
}

func (h *ProcSysNetUnix) GetEnabled() bool {
	return h.Enabled
}

func (h *ProcSysNetUnix) SetEnabled(b bool) {
	h.Enabled = b
}

func (h *ProcSysNetUnix) GetResourcesList() []string {

	var resources []string

	for resourceKey, resource := range h.EmuResourceMap {
		resource.Mutex.Lock()
		if !resource.Enabled {
			resource.Mutex.Unlock()
			continue
		}
		resource.Mutex.Unlock()

		resources = append(resources, filepath.Join(h.GetPath(), resourceKey))
	}

	return resources
}
func (h *ProcSysNetUnix) GetResourceMutex(n domain.IOnodeIface) *sync.Mutex {
	resource, ok := h.EmuResourceMap[n.Name()]
	if !ok {
		return nil
	}

	return &resource.Mutex
}

func (h *ProcSysNetUnix) SetService(hs domain.HandlerServiceIface) {
	h.Service = hs
}
