package cli

import (
	"context"
	"errors"
	"flag"
	"fmt"
	"net/http"
	"strings"
	"time"

	"github.com/qdm12/gluetun/internal/configuration/settings"
	"github.com/qdm12/gluetun/internal/constants"
	"github.com/qdm12/gluetun/internal/constants/providers"
	"github.com/qdm12/gluetun/internal/provider"
	"github.com/qdm12/gluetun/internal/publicip"
	"github.com/qdm12/gluetun/internal/storage"
	"github.com/qdm12/gluetun/internal/updater"
	"github.com/qdm12/gluetun/internal/updater/resolver"
	"github.com/qdm12/gluetun/internal/updater/unzip"
)

var (
	ErrModeUnspecified     = errors.New("at least one of -enduser or -maintainer must be specified")
	ErrNoProviderSpecified = errors.New("no provider was specified")
)

type UpdaterLogger interface {
	Info(s string)
	Warn(s string)
	Error(s string)
}

func (c *CLI) Update(ctx context.Context, args []string, logger UpdaterLogger) error {
	options := settings.Updater{}
	var endUserMode, maintainerMode, updateAll bool
	var csvProviders string
	flagSet := flag.NewFlagSet("update", flag.ExitOnError)
	flagSet.BoolVar(&endUserMode, "enduser", false, "Write results to /gluetun/servers.json (for end users)")
	flagSet.BoolVar(&maintainerMode, "maintainer", false,
		"Write results to ./internal/storage/servers.json to modify the program (for maintainers)")
	flagSet.StringVar(&options.DNSAddress, "dns", "8.8.8.8", "DNS resolver address to use")
	flagSet.BoolVar(&updateAll, "all", false, "Update servers for all VPN providers")
	flagSet.StringVar(&csvProviders, "providers", "", "CSV string of VPN providers to update server data for")
	if err := flagSet.Parse(args); err != nil {
		return err
	}

	if !endUserMode && !maintainerMode {
		return ErrModeUnspecified
	}

	if updateAll {
		options.Providers = providers.All()
	} else {
		if csvProviders == "" {
			return ErrNoProviderSpecified
		}
		options.Providers = strings.Split(csvProviders, ",")
	}

	options.SetDefaults(options.Providers[0])

	err := options.Validate()
	if err != nil {
		return fmt.Errorf("options validation failed: %w", err)
	}

	storage, err := storage.New(logger, constants.ServersData)
	if err != nil {
		return fmt.Errorf("cannot create servers storage: %w", err)
	}

	const clientTimeout = 10 * time.Second
	httpClient := &http.Client{Timeout: clientTimeout}
	unzipper := unzip.New(httpClient)
	parallelResolver := resolver.NewParallelResolver(options.DNSAddress)
	ipFetcher := publicip.NewFetch(httpClient)

	providers := provider.NewProviders(storage, time.Now, logger, httpClient,
		unzipper, parallelResolver, ipFetcher)

	updater := updater.New(httpClient, storage, providers, logger)
	err = updater.UpdateServers(ctx, options.Providers)
	if err != nil {
		return fmt.Errorf("cannot update server information: %w", err)
	}

	if maintainerMode {
		err := storage.FlushToFile(c.repoServersPath)
		if err != nil {
			return fmt.Errorf("cannot write servers data to embedded JSON file: %w", err)
		}
	}

	return nil
}