package services

import (
	"crypto/rand"
	"encoding/base64"
	"encoding/json"
	"errors"
	"time"

	"gorm.io/datatypes"
	"gorm.io/gorm"

	"oidc-oauth2-server/models"
)

type ClientService struct {
	db *gorm.DB
}

type ClientResponse struct {
	ClientID                string    `json:"client_id"`
	ClientSecret            string    `json:"client_secret,omitempty"`
	RegistrationAccessToken string    `json:"registration_access_token,omitempty"`
	RegistrationClientURI   string    `json:"registration_client_uri,omitempty"`
	ClientIDIssuedAt        time.Time `json:"client_id_issued_at"`
	ClientSecretExpiresAt   time.Time `json:"client_secret_expires_at"`
	RedirectURIs            []string  `json:"redirect_uris"`
	TokenEndpointAuthMethod string    `json:"token_endpoint_auth_method"`
	GrantTypes              []string  `json:"grant_types"`
	ResponseTypes           []string  `json:"response_types"`
	ClientName              string    `json:"client_name"`
	ClientURI               string    `json:"client_uri"`
	LogoURI                 string    `json:"logo_uri"`
	Scope                   string    `json:"scope"`
	Contacts                []string  `json:"contacts"`
	TosURI                  string    `json:"tos_uri"`
	PolicyURI               string    `json:"policy_uri"`
	SoftwareID              string    `json:"software_id"`
	SoftwareVersion         string    `json:"software_version"`
}

type ClientRegistrationRequest struct {
	RedirectURIs            []string `json:"redirect_uris" binding:"required"`
	TokenEndpointAuthMethod string   `json:"token_endpoint_auth_method"`
	GrantTypes              []string `json:"grant_types"`
	ResponseTypes           []string `json:"response_types"`
	ClientName              string   `json:"client_name"`
	ClientURI               string   `json:"client_uri"`
	LogoURI                 string   `json:"logo_uri"`
	Scope                   string   `json:"scope"`
	Contacts                []string `json:"contacts"`
	TosURI                  string   `json:"tos_uri"`
	PolicyURI               string   `json:"policy_uri"`
	SoftwareID              string   `json:"software_id"`
	SoftwareVersion         string   `json:"software_version"`
}

func NewClientService(db *gorm.DB) *ClientService {
	return &ClientService{db: db}
}

func (s *ClientService) RegisterClient(req *ClientRegistrationRequest) (*ClientResponse, error) {
	// 生成客户端凭证
	clientID := generateSecureToken(32)
	clientSecret := generateSecureToken(48)

	// 设置默认值
	if len(req.GrantTypes) == 0 {
		req.GrantTypes = []string{"authorization_code"}
	}
	if len(req.ResponseTypes) == 0 {
		req.ResponseTypes = []string{"code"}
	}
	if req.TokenEndpointAuthMethod == "" {
		req.TokenEndpointAuthMethod = "client_secret_basic"
	}

	// 将字符串数组转换为 JSON
	redirectURIsJSON, _ := json.Marshal(req.RedirectURIs)
	grantTypesJSON, _ := json.Marshal(req.GrantTypes)
	responseTypesJSON, _ := json.Marshal(req.ResponseTypes)
	scopesJSON, _ := json.Marshal([]string{req.Scope})
	contactsJSON, _ := json.Marshal(req.Contacts)

	// 创建客户端记录
	client := &models.Client{
		ClientID:                clientID,
		ClientSecret:            clientSecret,
		RedirectURIs:            datatypes.JSON(redirectURIsJSON),
		TokenEndpointAuthMethod: req.TokenEndpointAuthMethod,
		GrantTypes:              datatypes.JSON(grantTypesJSON),
		ResponseTypes:           datatypes.JSON(responseTypesJSON),
		ClientName:              req.ClientName,
		ClientURI:               req.ClientURI,
		LogoURI:                 req.LogoURI,
		Scopes:                  datatypes.JSON(scopesJSON),
		Contacts:                datatypes.JSON(contactsJSON),
		TosURI:                  req.TosURI,
		PolicyURI:               req.PolicyURI,
		SoftwareID:              req.SoftwareID,
		SoftwareVersion:         req.SoftwareVersion,
		IsActive:                true,
		CreatedAt:               time.Now(),
		UpdatedAt:               time.Now(),
	}

	if err := s.db.Create(client).Error; err != nil {
		return nil, err
	}

	// 构建响应
	return &ClientResponse{
		ClientID:                clientID,
		ClientSecret:            clientSecret,
		ClientIDIssuedAt:        client.CreatedAt,
		ClientSecretExpiresAt:   time.Time{}, // 永不过期
		RedirectURIs:            req.RedirectURIs,
		TokenEndpointAuthMethod: req.TokenEndpointAuthMethod,
		GrantTypes:              req.GrantTypes,
		ResponseTypes:           req.ResponseTypes,
		ClientName:              req.ClientName,
		ClientURI:               req.ClientURI,
		LogoURI:                 req.LogoURI,
		Scope:                   req.Scope,
		Contacts:                req.Contacts,
		TosURI:                  req.TosURI,
		PolicyURI:               req.PolicyURI,
		SoftwareID:              req.SoftwareID,
		SoftwareVersion:         req.SoftwareVersion,
	}, nil
}

func (s *ClientService) GetClient(clientID string) (*ClientResponse, error) {
	var client models.Client
	if err := s.db.Where("client_id = ? AND is_active = ?", clientID, true).First(&client).Error; err != nil {
		return nil, err
	}

	// 解析 JSON 字段
	var redirectURIs, grantTypes, responseTypes, scopes, contacts []string
	json.Unmarshal(client.RedirectURIs, &redirectURIs)
	json.Unmarshal(client.GrantTypes, &grantTypes)
	json.Unmarshal(client.ResponseTypes, &responseTypes)
	json.Unmarshal(client.Scopes, &scopes)
	json.Unmarshal(client.Contacts, &contacts)

	return &ClientResponse{
		ClientID:                client.ClientID,
		ClientIDIssuedAt:        client.CreatedAt,
		RedirectURIs:            redirectURIs,
		TokenEndpointAuthMethod: client.TokenEndpointAuthMethod,
		GrantTypes:              grantTypes,
		ResponseTypes:           responseTypes,
		ClientName:              client.ClientName,
		ClientURI:               client.ClientURI,
		LogoURI:                 client.LogoURI,
		Scope:                   scopes[0],
		Contacts:                contacts,
		TosURI:                  client.TosURI,
		PolicyURI:               client.PolicyURI,
		SoftwareID:              client.SoftwareID,
		SoftwareVersion:         client.SoftwareVersion,
	}, nil
}

func (s *ClientService) UpdateClient(clientID string, req *ClientRegistrationRequest) (*ClientResponse, error) {
	var client models.Client
	if err := s.db.Where("client_id = ? AND is_active = ?", clientID, true).First(&client).Error; err != nil {
		return nil, err
	}

	// 将字符串数组转换为 JSON
	redirectURIsJSON, _ := json.Marshal(req.RedirectURIs)
	grantTypesJSON, _ := json.Marshal(req.GrantTypes)
	responseTypesJSON, _ := json.Marshal(req.ResponseTypes)
	scopesJSON, _ := json.Marshal([]string{req.Scope})
	contactsJSON, _ := json.Marshal(req.Contacts)

	// 更新客户端信息
	client.RedirectURIs = datatypes.JSON(redirectURIsJSON)
	client.GrantTypes = datatypes.JSON(grantTypesJSON)
	client.ResponseTypes = datatypes.JSON(responseTypesJSON)
	client.Scopes = datatypes.JSON(scopesJSON)
	client.Contacts = datatypes.JSON(contactsJSON)
	client.UpdatedAt = time.Now()

	if err := s.db.Save(&client).Error; err != nil {
		return nil, err
	}

	return s.GetClient(clientID)
}

func (s *ClientService) DeleteClient(clientID string) error {
	result := s.db.Model(&models.Client{}).Where("client_id = ?", clientID).Update("is_active", false)
	if result.Error != nil {
		return result.Error
	}
	if result.RowsAffected == 0 {
		return errors.New("client not found")
	}
	return nil
}

func generateSecureToken(length int) string {
	b := make([]byte, length)
	if _, err := rand.Read(b); err != nil {
		return ""
	}
	return base64.RawURLEncoding.EncodeToString(b)
}