package auth

import (
	"context"
	"errors"
	"fmt"
	"net/url"

	"github.com/user-management-system/internal/auth/providers"
)

// OAuthProvider OAuth提供商类型
type OAuthProvider string

const (
	OAuthProviderWeChat   OAuthProvider = "wechat"
	OAuthProviderQQ       OAuthProvider = "qq"
	OAuthProviderWeibo    OAuthProvider = "weibo"
	OAuthProviderGoogle    OAuthProvider = "google"
	OAuthProviderFacebook OAuthProvider = "facebook"
	OAuthProviderTwitter  OAuthProvider = "twitter"
	OAuthProviderGitHub   OAuthProvider = "github"
	OAuthProviderAlipay   OAuthProvider = "alipay"
	OAuthProviderDouyin   OAuthProvider = "douyin"
)

// OAuthUser OAuth用户信息
type OAuthUser struct {
	Provider OAuthProvider          `json:"provider"`
	OpenID   string                 `json:"open_id"`
	UnionID  string                 `json:"union_id,omitempty"`
	Nickname string                 `json:"nickname"`
	Avatar   string                 `json:"avatar"`
	Gender   string                 `json:"gender,omitempty"`
	Email    string                 `json:"email,omitempty"`
	Phone    string                 `json:"phone,omitempty"`
	Extra    map[string]interface{} `json:"extra,omitempty"`
}

// OAuthToken OAuth令牌
type OAuthToken struct {
	AccessToken  string `json:"access_token"`
	RefreshToken string `json:"refresh_token,omitempty"`
	ExpiresIn    int64  `json:"expires_in"`
	TokenType    string `json:"token_type"`
	OpenID       string `json:"open_id,omitempty"` // 微信等需要 openid
}

// OAuthConfig OAuth配置
type OAuthConfig struct {
	ClientID     string `json:"client_id"`
	ClientSecret string `json:"client_secret"`
	RedirectURI  string `json:"redirect_uri"`
	Scope        string `json:"scope"`
	AuthURL      string `json:"auth_url"`
	TokenURL     string `json:"token_url"`
	UserInfoURL  string `json:"user_info_url"`
}

// OAuthManager OAuth管理器接口
type OAuthManager interface {
	// GetAuthURL 获取授权URL
	GetAuthURL(provider OAuthProvider, state string) (string, error)

	// ExchangeCode 换取访问令牌
	ExchangeCode(provider OAuthProvider, code string) (*OAuthToken, error)

	// GetUserInfo 获取用户信息
	GetUserInfo(provider OAuthProvider, token *OAuthToken) (*OAuthUser, error)

	// ValidateToken 验证令牌
	ValidateToken(token string) (bool, error)

	// GetConfig 获取OAuth配置
	GetConfig(provider OAuthProvider) (*OAuthConfig, bool)

	// GetEnabledProviders 获取已启用的OAuth提供商
	GetEnabledProviders() []OAuthProviderInfo
}

// OAuthProviderInfo OAuth提供商信息
type OAuthProviderInfo struct {
	Provider OAuthProvider `json:"provider"`
	Enabled  bool          `json:"enabled"`
	Name     string        `json:"name"`
}

// providerEntry 内部 provider 条目
type providerEntry struct {
	config      *OAuthConfig
	google      *providers.GoogleProvider
	wechat      *providers.WeChatProvider
	wechatRedir string
	qq          *providers.QQProvider
	github      *providers.GitHubProvider
	alipay      *providers.AlipayProvider
	douyin      *providers.DouyinProvider
}

// DefaultOAuthManager 默认OAuth管理器（集成真实 provider HTTP 调用）
type DefaultOAuthManager struct {
	entries map[OAuthProvider]*providerEntry
}

// NewOAuthManager 创建OAuth管理器
func NewOAuthManager() *DefaultOAuthManager {
	return &DefaultOAuthManager{
		entries: make(map[OAuthProvider]*providerEntry),
	}
}

// RegisterProvider 注册OAuth提供商（保留旧接口，仅存储配置）
func (m *DefaultOAuthManager) RegisterProvider(provider OAuthProvider, config *OAuthConfig) {
	entry := &providerEntry{config: config}

	switch provider {
	case OAuthProviderGoogle:
		entry.google = providers.NewGoogleProvider(config.ClientID, config.ClientSecret, config.RedirectURI)
	case OAuthProviderWeChat:
		entry.wechat = providers.NewWeChatProvider(config.ClientID, config.ClientSecret, "web")
		entry.wechatRedir = config.RedirectURI
	case OAuthProviderQQ:
		entry.qq = providers.NewQQProvider(config.ClientID, config.ClientSecret, config.RedirectURI)
	case OAuthProviderGitHub:
		entry.github = providers.NewGitHubProvider(config.ClientID, config.ClientSecret, config.RedirectURI)
	case OAuthProviderAlipay:
		// 支付宝使用 ClientID 存储 AppID，ClientSecret 存储 RSA 私钥
		entry.alipay = providers.NewAlipayProvider(config.ClientID, config.ClientSecret, config.RedirectURI, false)
	case OAuthProviderDouyin:
		entry.douyin = providers.NewDouyinProvider(config.ClientID, config.ClientSecret, config.RedirectURI)
	}

	m.entries[provider] = entry
}

// GetConfig 获取OAuth配置
func (m *DefaultOAuthManager) GetConfig(provider OAuthProvider) (*OAuthConfig, bool) {
	entry, ok := m.entries[provider]
	if !ok {
		return nil, false
	}
	return entry.config, true
}

// GetAuthURL 获取授权URL（使用真实 provider 实现）
func (m *DefaultOAuthManager) GetAuthURL(provider OAuthProvider, state string) (string, error) {
	entry, ok := m.entries[provider]
	if !ok {
		return "", ErrOAuthProviderNotSupported
	}

	switch provider {
	case OAuthProviderGoogle:
		if entry.google != nil {
			resp, err := entry.google.GetAuthURL(state)
			if err != nil {
				return "", err
			}
			return resp.URL, nil
		}
	case OAuthProviderWeChat:
		if entry.wechat != nil {
			resp, err := entry.wechat.GetAuthURL(entry.wechatRedir, state)
			if err != nil {
				return "", err
			}
			return resp.URL, nil
		}
	case OAuthProviderQQ:
		if entry.qq != nil {
			resp, err := entry.qq.GetAuthURL(state)
			if err != nil {
				return "", err
			}
			return resp.URL, nil
		}
	case OAuthProviderGitHub:
		if entry.github != nil {
			return entry.github.GetAuthURL(state)
		}
	case OAuthProviderAlipay:
		if entry.alipay != nil {
			return entry.alipay.GetAuthURL(state)
		}
	case OAuthProviderDouyin:
		if entry.douyin != nil {
			return entry.douyin.GetAuthURL(state)
		}
	}

	// 通用 fallback：按标准 OAuth2 拼接 URL（对 QQ/微博/Twitter/Facebook）
	config := entry.config
	if config == nil {
		return "", ErrOAuthProviderNotSupported
	}
	return fmt.Sprintf("%s?client_id=%s&redirect_uri=%s&response_type=code&scope=%s&state=%s",
		config.AuthURL,
		url.QueryEscape(config.ClientID),
		url.QueryEscape(config.RedirectURI),
		url.QueryEscape(config.Scope),
		url.QueryEscape(state),
	), nil
}

// ExchangeCode 换取访问令牌（使用真实 provider 实现）
func (m *DefaultOAuthManager) ExchangeCode(provider OAuthProvider, code string) (*OAuthToken, error) {
	entry, ok := m.entries[provider]
	if !ok {
		return nil, ErrOAuthProviderNotSupported
	}

	ctx := context.Background()

	switch provider {
	case OAuthProviderGoogle:
		if entry.google != nil {
			resp, err := entry.google.ExchangeCode(ctx, code)
			if err != nil {
				return nil, err
			}
			return &OAuthToken{
				AccessToken:  resp.AccessToken,
				RefreshToken: resp.RefreshToken,
				ExpiresIn:    int64(resp.ExpiresIn),
				TokenType:    resp.TokenType,
			}, nil
		}
	case OAuthProviderWeChat:
		if entry.wechat != nil {
			resp, err := entry.wechat.ExchangeCode(ctx, code)
			if err != nil {
				return nil, err
			}
			return &OAuthToken{
				AccessToken:  resp.AccessToken,
				RefreshToken: resp.RefreshToken,
				ExpiresIn:    int64(resp.ExpiresIn),
				TokenType:    "Bearer",
				OpenID:       resp.OpenID,
			}, nil
		}
	case OAuthProviderQQ:
		if entry.qq != nil {
			resp, err := entry.qq.ExchangeCode(ctx, code)
			if err != nil {
				return nil, err
			}
			openIDResp, err := entry.qq.GetOpenID(ctx, resp.AccessToken)
			if err != nil {
				return nil, err
			}
			return &OAuthToken{
				AccessToken:  resp.AccessToken,
				RefreshToken: resp.RefreshToken,
				ExpiresIn:    int64(resp.ExpiresIn),
				TokenType:    "Bearer",
				OpenID:       openIDResp.OpenID,
			}, nil
		}
	case OAuthProviderGitHub:
		if entry.github != nil {
			resp, err := entry.github.ExchangeCode(ctx, code)
			if err != nil {
				return nil, err
			}
			return &OAuthToken{
				AccessToken: resp.AccessToken,
				TokenType:   resp.TokenType,
			}, nil
		}
	case OAuthProviderAlipay:
		if entry.alipay != nil {
			resp, err := entry.alipay.ExchangeCode(ctx, code)
			if err != nil {
				return nil, err
			}
			return &OAuthToken{
				AccessToken:  resp.AccessToken,
				RefreshToken: resp.RefreshToken,
				ExpiresIn:    int64(resp.ExpiresIn),
				TokenType:    "Bearer",
				OpenID:       resp.UserID,
			}, nil
		}
	case OAuthProviderDouyin:
		if entry.douyin != nil {
			resp, err := entry.douyin.ExchangeCode(ctx, code)
			if err != nil {
				return nil, err
			}
			return &OAuthToken{
				AccessToken:  resp.Data.AccessToken,
				RefreshToken: resp.Data.RefreshToken,
				ExpiresIn:    int64(resp.Data.ExpiresIn),
				TokenType:    "Bearer",
				OpenID:       resp.Data.OpenID,
			}, nil
		}
	}

	return nil, fmt.Errorf("provider %s: real HTTP exchange not implemented yet", provider)
}

// GetUserInfo 获取用户信息（使用真实 provider 实现）
func (m *DefaultOAuthManager) GetUserInfo(provider OAuthProvider, token *OAuthToken) (*OAuthUser, error) {
	entry, ok := m.entries[provider]
	if !ok {
		return nil, ErrOAuthProviderNotSupported
	}

	ctx := context.Background()

	switch provider {
	case OAuthProviderGoogle:
		if entry.google != nil {
			info, err := entry.google.GetUserInfo(ctx, token.AccessToken)
			if err != nil {
				return nil, err
			}
			return &OAuthUser{
				Provider: provider,
				OpenID:   info.ID,
				Nickname: info.Name,
				Avatar:   info.Picture,
				Email:    info.Email,
			}, nil
		}
	case OAuthProviderWeChat:
		if entry.wechat != nil {
			openID := token.OpenID
			info, err := entry.wechat.GetUserInfo(ctx, token.AccessToken, openID)
			if err != nil {
				return nil, err
			}
			gender := ""
			switch info.Sex {
			case 1:
				gender = "male"
			case 2:
				gender = "female"
			}
			return &OAuthUser{
				Provider: provider,
				OpenID:   info.OpenID,
				UnionID:  info.UnionID,
				Nickname: info.Nickname,
				Avatar:   info.HeadImgURL,
				Gender:   gender,
			}, nil
		}
	case OAuthProviderQQ:
		if entry.qq != nil {
			info, err := entry.qq.GetUserInfo(ctx, token.AccessToken, token.OpenID)
			if err != nil {
				return nil, err
			}
			avatar := info.FigureURL2
			if avatar == "" {
				avatar = info.FigureURL1
			}
			if avatar == "" {
				avatar = info.FigureURL
			}
			return &OAuthUser{
				Provider: provider,
				OpenID:   token.OpenID,
				Nickname: info.Nickname,
				Avatar:   avatar,
				Gender:   info.Gender,
				Extra: map[string]interface{}{
					"province": info.Province,
					"city":     info.City,
					"year":     info.Year,
				},
			}, nil
		}
	case OAuthProviderGitHub:
		if entry.github != nil {
			info, err := entry.github.GetUserInfo(ctx, token.AccessToken)
			if err != nil {
				return nil, err
			}
			nickname := info.Name
			if nickname == "" {
				nickname = info.Login
			}
			return &OAuthUser{
				Provider: provider,
				OpenID:   fmt.Sprintf("%d", info.ID),
				Nickname: nickname,
				Email:    info.Email,
			}, nil
		}
	case OAuthProviderAlipay:
		if entry.alipay != nil {
			info, err := entry.alipay.GetUserInfo(ctx, token.AccessToken)
			if err != nil {
				return nil, err
			}
			return &OAuthUser{
				Provider: provider,
				OpenID:   info.UserID,
				Nickname: info.Nickname,
				Avatar:   info.Avatar,
			}, nil
		}
	case OAuthProviderDouyin:
		if entry.douyin != nil {
			info, err := entry.douyin.GetUserInfo(ctx, token.AccessToken, token.OpenID)
			if err != nil {
				return nil, err
			}
			gender := ""
			switch info.Data.Gender {
			case 1:
				gender = "male"
			case 2:
				gender = "female"
			}
			return &OAuthUser{
				Provider: provider,
				OpenID:   info.Data.OpenID,
				UnionID:  info.Data.UnionID,
				Nickname: info.Data.Nickname,
				Avatar:   info.Data.Avatar,
				Gender:   gender,
			}, nil
		}
	}

	return nil, fmt.Errorf("provider %s: real HTTP user info not implemented yet", provider)
}

// ValidateToken 验证令牌
// 注意：由于 ValidateToken 不持有 provider 上下文，无法进行真正的 token 验证
// 对于需要验证 token 的场景，应使用 GetUserInfo 通过 provider 的 userinfo 端点验证
// 如果没有可用的 provider，返回错误
func (m *DefaultOAuthManager) ValidateToken(token string) (bool, error) {
	if len(token) == 0 {
		return false, nil
	}
	// 由于缺乏 provider 上下文，无法进行有意义的验证
	// 遍历所有已启用的 provider，尝试通过 GetUserInfo 验证
	// 如果没有任何 provider 可用，返回错误而不是默认通过
	providers := m.GetEnabledProviders()
	if len(providers) == 0 {
		return false, errors.New("no OAuth providers configured")
	}
	// 尝试任一 provider 的 userinfo 端点验证
	tokenObj := &OAuthToken{AccessToken: token}
	for _, p := range providers {
		if _, err := m.GetUserInfo(p.Provider, tokenObj); err == nil {
			return true, nil
		}
	}
	return false, nil
}

// ValidateTokenWithProvider 通过指定 provider 验证令牌
func (m *DefaultOAuthManager) ValidateTokenWithProvider(provider OAuthProvider, token string) (bool, error) {
	if token == "" {
		return false, nil
	}

	cfg, ok := m.GetConfig(provider)
	if !ok || cfg.ClientID == "" {
		return false, fmt.Errorf("provider %s not configured", provider)
	}

	// 通过 provider 的 userinfo 端点验证 token
	tokenObj := &OAuthToken{AccessToken: token}
	_, err := m.GetUserInfo(provider, tokenObj)
	if err != nil {
		return false, err
	}
	return true, nil
}

// GetEnabledProviders 获取已启用的OAuth提供商
func (m *DefaultOAuthManager) GetEnabledProviders() []OAuthProviderInfo {
	providerNames := map[OAuthProvider]string{
		OAuthProviderGoogle:       "Google",
		OAuthProviderWeChat:   "微信",
		OAuthProviderQQ:       "QQ",
		OAuthProviderWeibo:    "微博",
		OAuthProviderFacebook: "Facebook",
		OAuthProviderTwitter:  "Twitter",
		OAuthProviderGitHub:   "GitHub",
		OAuthProviderAlipay:   "支付宝",
		OAuthProviderDouyin:   "抖音",
	}

	var result []OAuthProviderInfo
	for provider, entry := range m.entries {
		name := providerNames[provider]
		if name == "" {
			name = string(provider)
		}
		result = append(result, OAuthProviderInfo{
			Provider: provider,
			Enabled:  entry.config != nil,
			Name:     name,
		})
	}
	return result
}