package auth

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

	"gopkg.in/yaml.v3"
)

type teaLogin struct {
	Name    string `yaml:"name"`
	URL     string `yaml:"url"`
	Token   string `yaml:"token"`
	Default bool   `yaml:"default"`
}

type teaConfig struct {
	Logins []teaLogin `yaml:"logins"`
}

func parseTea(path string) (*teaConfig, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("read tea config %s: %w", path, err)
	}
	var cfg teaConfig
	if err := yaml.Unmarshal(data, &cfg); err != nil {
		return nil, fmt.Errorf("parse tea config %s: %w", path, err)
	}
	return &cfg, nil
}

func defaultTeaConfigPath() (string, error) {
	home, err := os.UserHomeDir()
	if err != nil {
		return "", fmt.Errorf("resolve home dir: %w", err)
	}
	return filepath.Join(home, ".config", "tea", "config.yml"), nil
}

// ResolveGiteaToken returns a Gitea token for the given host.
// Resolution order:
//  1. GITEA_TOKEN env var (if non-empty)
//  2. ~/.config/tea/config.yml: entry matching host, else default login
func ResolveGiteaToken(host string) (string, error) {
	return resolveGiteaToken(host, "")
}

func resolveGiteaToken(host, teaConfigPath string) (string, error) {
	if tok := os.Getenv("GITEA_TOKEN"); tok != "" {
		return tok, nil
	}
	if teaConfigPath == "" {
		var err error
		teaConfigPath, err = defaultTeaConfigPath()
		if err != nil {
			return "", err
		}
	}
	cfg, err := parseTea(teaConfigPath)
	if err != nil {
		return "", err
	}
	if len(cfg.Logins) == 0 {
		return "", fmt.Errorf("no logins in tea config %s", teaConfigPath)
	}

	want := strings.TrimRight(strings.ToLower(host), "/")

	// First try exact host match.
	for _, l := range cfg.Logins {
		loginHost := strings.TrimRight(strings.ToLower(l.URL), "/")
		if loginHost == want {
			if l.Token == "" {
				return "", fmt.Errorf("tea config login for host %s has empty token", host)
			}
			return l.Token, nil
		}
	}

	// Fall back to default login.
	var chosen *teaLogin
	for i := range cfg.Logins {
		if cfg.Logins[i].Default {
			chosen = &cfg.Logins[i]
			break
		}
	}
	if chosen == nil {
		chosen = &cfg.Logins[0]
	}
	if chosen.Token == "" {
		return "", fmt.Errorf("tea config default login has empty token")
	}
	return chosen.Token, nil
}