package openwrt

import (
	"context"
	"io"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"strings"

	"forge.cadoles.com/Cadoles/emissary/internal/agent"
	"forge.cadoles.com/Cadoles/emissary/internal/agent/controller/openwrt/spec/sysupgrade"
	"github.com/pkg/errors"
	"gitlab.com/wpetit/goweb/logger"
)

type SysUpgradeController struct {
	client          *http.Client
	command         string
	args            []string
	firmwareVersion FirmwareVersion
}

// Name implements agent.Controller
func (*SysUpgradeController) Name() string {
	return "sysupgrade-controller"
}

// Reconcile implements agent.Controller
func (c *SysUpgradeController) Reconcile(ctx context.Context, state *agent.State) error {
	sysSpec := sysupgrade.NewSpec()

	if err := state.GetSpec(sysupgrade.Name, sysSpec); err != nil {
		if errors.Is(err, agent.ErrSpecNotFound) {
			logger.Info(ctx, "could not find sysupgrade spec, doing nothing")

			return nil
		}

		return errors.WithStack(err)
	}

	firmwareVersion, err := c.firmwareVersion.FirmwareVersion(ctx)
	if err != nil {
		return errors.WithStack(err)
	}

	ctx = logger.With(ctx,
		logger.F("currentFirmwareVersion", firmwareVersion),
		logger.F("newFirmwareVersion", sysSpec.Version),
	)

	if firmwareVersion == sysSpec.Version {
		logger.Info(ctx, "firmware version did not change, doing nothing")

		return nil
	}

	downloadDir, err := os.MkdirTemp(os.TempDir(), "emissary_sysupgrade_*")
	if err != nil {
		return errors.WithStack(err)
	}

	defer func() {
		if err := os.RemoveAll(downloadDir); err != nil {
			logger.Error(
				ctx, "could not remove download direction",
				logger.E(errors.WithStack(err)),
				logger.F("downloadDir", downloadDir),
			)
		}
	}()

	firmwareFile := filepath.Join(downloadDir, "firmware.bin")

	logger.Info(
		ctx, "downloading firmware",
		logger.F("url", sysSpec.URL), logger.F("sha256sum", sysSpec.SHA256Sum),
	)

	if err := c.downloadFile(ctx, sysSpec.URL, sysSpec.SHA256Sum, firmwareFile); err != nil {
		return errors.WithStack(err)
	}

	logger.Info(ctx, "upgrading firmware")

	if err := c.upgradeFirmware(ctx, firmwareFile); err != nil {
		return errors.WithStack(err)
	}

	return nil
}

func (c *SysUpgradeController) downloadFile(ctx context.Context, url string, sha256sum string, dest string) error {
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
	if err != nil {
		return errors.WithStack(err)
	}

	res, err := c.client.Do(req)
	if err != nil {
		return errors.WithStack(err)
	}

	defer func() {
		if err := res.Body.Close(); err != nil && !errors.Is(err, os.ErrClosed) {
			panic(errors.WithStack(err))
		}
	}()

	tmp, err := os.CreateTemp(filepath.Dir(dest), "download_")
	if err != nil {
		return errors.WithStack(err)
	}

	defer func() {
		if err := os.Remove(tmp.Name()); err != nil && !os.IsNotExist(err) {
			panic(errors.WithStack(err))
		}
	}()

	if _, err := io.Copy(tmp, res.Body); err != nil {
		return errors.WithStack(err)
	}

	tmpFileHash, err := hash(tmp.Name())
	if err != nil {
		return errors.WithStack(err)
	}

	if tmpFileHash != sha256sum {
		return errors.Errorf("sha256 sum mismatch: expected '%s', got '%s'", sha256sum, tmpFileHash)
	}

	if err := os.Rename(tmp.Name(), dest); err != nil {
		return errors.WithStack(err)
	}

	return nil
}

func (c *SysUpgradeController) upgradeFirmware(ctx context.Context, firmwareFile string) error {
	templatizedArgs := make([]string, len(c.args))
	for i, a := range c.args {
		templatizedArgs[i] = strings.Replace(a, FirmwareFileTemplate, firmwareFile, 1)
	}

	command := exec.CommandContext(ctx, c.command, templatizedArgs...)

	command.Stdout = os.Stdout
	command.Stderr = os.Stderr

	logger.Debug(ctx, "executing command", logger.F("command", c.command), logger.F("args", templatizedArgs))

	if err := command.Run(); err != nil {
		return errors.WithStack(err)
	}

	return nil
}

func NewSysUpgradeController(funcs ...SysUpgradeOptionFunc) *SysUpgradeController {
	opts := defaultSysUpgradeOptions()
	for _, fn := range funcs {
		fn(opts)
	}

	return &SysUpgradeController{
		command:         opts.Command,
		args:            opts.Args,
		client:          opts.Client,
		firmwareVersion: opts.FirmwareVersion,
	}
}

var _ agent.Controller = &SysUpgradeController{}