package chatgpt

import (
	"encoding/json"
	"fmt"
	"log"
	"net/http"

	"gpt-plus/pkg/httpclient"
)

const (
	defaultUserAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/145.0.0.0 Safari/537.36"
	chatGPTOrigin    = "https://chatgpt.com"
)

// defaultLanguage is the package-level language setting used by standalone functions
// that don't have access to a Session. Set via SetDefaultLanguage().
var defaultLanguage = "en-US"

// StatusFunc is a callback for reporting progress to the user.
type StatusFunc func(format string, args ...interface{})

// GetDefaultUA returns the default User-Agent string.
func GetDefaultUA() string {
	return defaultUserAgent
}

// SetDefaultLanguage sets the default oai-language for standalone functions (CheckAccount, etc.).
func SetDefaultLanguage(lang string) {
	if lang != "" {
		defaultLanguage = lang
	}
}

// GetDefaultLanguage returns the current default language setting.
func GetDefaultLanguage() string {
	return defaultLanguage
}

// Session holds authentication state for a ChatGPT session.
type Session struct {
	Client       *httpclient.Client
	AccessToken  string
	RefreshToken string
	IDToken      string
	DeviceID     string
	AccountID    string
	UserID       string
	Language     string // browser locale e.g. "en-US" — derived from card country
}

// NewSession creates a new Session with all auth details.
func NewSession(client *httpclient.Client, accessToken, refreshToken, idToken, deviceID, accountID, userID string) *Session {
	return &Session{
		Client:       client,
		AccessToken:  accessToken,
		RefreshToken: refreshToken,
		IDToken:      idToken,
		DeviceID:     deviceID,
		AccountID:    accountID,
		UserID:       userID,
	}
}

// AuthHeaders returns common headers required for ChatGPT API requests.
func (s *Session) AuthHeaders() map[string]string {
	lang := s.Language
	if lang == "" {
		lang = defaultLanguage
	}
	return map[string]string{
		"Authorization": "Bearer " + s.AccessToken,
		"User-Agent":    defaultUserAgent,
		"Accept":        "*/*",
		"Content-Type":  "application/json",
		"Origin":        chatGPTOrigin,
		"Referer":       chatGPTOrigin + "/",
		"oai-device-id": s.DeviceID,
		"oai-language":  lang,
	}
}

// RefreshSession calls /api/auth/session to get a fresh access token
// (reflecting current plan status after Plus/Team activation).
func (s *Session) RefreshSession() error {
	sessionURL := "https://chatgpt.com/api/auth/session"

	headers := map[string]string{
		"User-Agent": defaultUserAgent,
		"Accept":     "application/json",
		"Origin":     chatGPTOrigin,
		"Referer":    chatGPTOrigin + "/",
	}

	resp, err := s.Client.Get(sessionURL, headers)
	if err != nil {
		return fmt.Errorf("refresh session request: %w", err)
	}

	body, err := httpclient.ReadBody(resp)
	if err != nil {
		return fmt.Errorf("read refresh session body: %w", err)
	}

	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("refresh session returned %d: %s", resp.StatusCode, string(body))
	}

	var result struct {
		AccessToken  string `json:"accessToken"`
		RefreshToken string `json:"refreshToken"`
		IDToken      string `json:"idToken"`
	}
	if err := json.Unmarshal(body, &result); err != nil {
		return fmt.Errorf("parse refresh session response: %w", err)
	}

	if result.AccessToken != "" {
		s.AccessToken = result.AccessToken
	}
	if result.RefreshToken != "" {
		s.RefreshToken = result.RefreshToken
	}
	if result.IDToken != "" {
		s.IDToken = result.IDToken
	}

	log.Printf("[session] tokens refreshed successfully")
	return nil
}