package config

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

	"gopkg.in/yaml.v3"
)

const defaultRefreshInterval = 30 * time.Second

type Config struct {
	ServerURL       string
	Username        string // optional, prefills the sign-in form
	RefreshInterval time.Duration
	Theme           string

	// LegacyAPIKey is set when the file still has an `api_key`. The TUI signs in
	// with a user account now and ignores it; this is only so it can say so.
	LegacyAPIKey bool

	// Team is the team to start on, by name or id. Empty shows every team the
	// key's user belongs to.
	Team string

	// Auth is how to sign in when the server offers a choice: "sso" starts a
	// single sign-on login straight away, "password" (or empty) shows the
	// password form. The server decides what is on offer; this only picks the
	// default among it.
	Auth string
}

type rawConfig struct {
	ServerURL       string `yaml:"server_url"`
	Username        string `yaml:"username,omitempty"`
	APIKey          string `yaml:"api_key,omitempty"`          // no longer used; see Config.LegacyAPIKey
	RefreshInterval int    `yaml:"refresh_interval,omitempty"` // seconds
	Theme           string `yaml:"theme,omitempty"`
	Team            string `yaml:"team,omitempty"`
	Auth            string `yaml:"auth,omitempty"`
}

func Load() (*Config, error) {
	dir, err := os.UserConfigDir()
	if err != nil {
		return nil, fmt.Errorf("cannot determine config directory: %w", err)
	}

	path := filepath.Join(dir, "terdut-tui", "config.yaml")
	data, err := os.ReadFile(path)
	if err != nil {
		if os.IsNotExist(err) {
			return nil, fmt.Errorf("config file not found at %s\n\nCreate it with:\n  server_url: https://terdut.example.com\n  username: <your-username>  # optional, prefills the sign-in form\n  theme: gruvbox-dark  # optional\n  team: Ops            # optional, team to start on\n  auth: sso            # optional, sso or password: how to sign in by default", path)
		}
		return nil, fmt.Errorf("cannot read config file: %w", err)
	}

	var raw rawConfig
	if err := yaml.Unmarshal(data, &raw); err != nil {
		return nil, fmt.Errorf("invalid config file: %w", err)
	}

	if raw.ServerURL == "" {
		return nil, fmt.Errorf("config: 'server_url' is required")
	}

	switch raw.Auth {
	case "", "password", "sso":
	default:
		return nil, fmt.Errorf("config: 'auth' must be sso or password, not %q", raw.Auth)
	}

	interval := defaultRefreshInterval
	if raw.RefreshInterval > 0 {
		interval = time.Duration(raw.RefreshInterval) * time.Second
	}

	return &Config{
		ServerURL:       raw.ServerURL,
		Username:        raw.Username,
		LegacyAPIKey:    raw.APIKey != "",
		RefreshInterval: interval,
		Theme:           raw.Theme,
		Team:            raw.Team,
		Auth:            raw.Auth,
	}, nil
}