package cli

import (
	"bufio"
	"fmt"
	"os"
	"os/exec"
	"runtime"
	"strings"
	"time"

	"github.com/spf13/cobra"

	"github.com/humdrum-tiv/dots-cli/internal/api"
	"github.com/humdrum-tiv/dots-cli/internal/auth"
	"github.com/humdrum-tiv/dots-cli/internal/config"
)

// RequireClient loads the stored token and returns a ready API client.
func RequireClient() (*api.Client, error) {
	token, err := auth.LoadToken()
	if err != nil {
		return nil, fmt.Errorf("not linked — run `dots auth`")
	}
	return api.New(config.BaseURL(), token), nil
}

// Today returns the current date (YYYY-MM-DD) in the device timezone.
func Today() string {
	return time.Now().Format("2006-01-02")
}

// TZ returns the device IANA timezone name. If the device timezone is not
// mappable to an IANA name, falls back to "UTC".
func TZ() string {
	if loc := time.Local.String(); loc != "Local" {
		return loc
	}
	return "UTC"
}

func openBrowser(url string) {
	if runtime.GOOS == "darwin" {
		exec.Command("open", url).Start()
	} else {
		exec.Command("xdg-open", url).Start()
	}
}

func NewAuthCmd() *cobra.Command {
	return &cobra.Command{
		Use:   "auth",
		Short: "Link this machine to your Dots account",
		RunE: func(cmd *cobra.Command, args []string) error {
			pageURL := config.BaseURL() + "/cli"
			fmt.Printf("Opening %s — generate a token there, then paste it here.\n", pageURL)
			openBrowser(pageURL)
			fmt.Print("Token: ")
			reader := bufio.NewReader(os.Stdin)
			line, _ := reader.ReadString('\n')
			token := strings.TrimSpace(line)
			if token == "" {
				return fmt.Errorf("no token entered")
			}
			client := api.New(config.BaseURL(), token)
			if _, err := client.GetDay(Today(), TZ()); err != nil {
				return fmt.Errorf("token check failed: %w", err)
			}
			if err := auth.SaveToken(token); err != nil {
				return fmt.Errorf("could not store token: %w", err)
			}
			fmt.Println("Linked. Try `dots today`.")
			return nil
		},
	}
}