package service

import (
	"context"
	"fmt"
	"time"

	infraerrors "github.com/Wei-Shaw/sub2api/internal/pkg/errors"
	"github.com/Wei-Shaw/sub2api/internal/pkg/pagination"
)

var (
	ErrAccountNotFound = infraerrors.NotFound("ACCOUNT_NOT_FOUND", "account not found")
	ErrAccountNilInput = infraerrors.BadRequest("ACCOUNT_NIL_INPUT", "account input cannot be nil")
)

type AccountRepository interface {
	Create(ctx context.Context, account *Account) error
	GetByID(ctx context.Context, id int64) (*Account, error)
	// GetByIDs fetches accounts by IDs in a single query.
	// It should return all accounts found (missing IDs are ignored).
	GetByIDs(ctx context.Context, ids []int64) ([]*Account, error)
	// ExistsByID 检查账号是否存在，仅返回布尔值，用于删除前的轻量级存在性检查
	ExistsByID(ctx context.Context, id int64) (bool, error)
	// GetByCRSAccountID finds an account previously synced from CRS.
	// Returns (nil, nil) if not found.
	GetByCRSAccountID(ctx context.Context, crsAccountID string) (*Account, error)
	Update(ctx context.Context, account *Account) error
	Delete(ctx context.Context, id int64) error

	List(ctx context.Context, params pagination.PaginationParams) ([]Account, *pagination.PaginationResult, error)
	ListWithFilters(ctx context.Context, params pagination.PaginationParams, platform, accountType, status, search string) ([]Account, *pagination.PaginationResult, error)
	ListByGroup(ctx context.Context, groupID int64) ([]Account, error)
	ListActive(ctx context.Context) ([]Account, error)
	ListByPlatform(ctx context.Context, platform string) ([]Account, error)

	UpdateLastUsed(ctx context.Context, id int64) error
	BatchUpdateLastUsed(ctx context.Context, updates map[int64]time.Time) error
	SetError(ctx context.Context, id int64, errorMsg string) error
	SetSchedulable(ctx context.Context, id int64, schedulable bool) error
	BindGroups(ctx context.Context, accountID int64, groupIDs []int64) error

	ListSchedulable(ctx context.Context) ([]Account, error)
	ListSchedulableByGroupID(ctx context.Context, groupID int64) ([]Account, error)
	ListSchedulableByPlatform(ctx context.Context, platform string) ([]Account, error)
	ListSchedulableByGroupIDAndPlatform(ctx context.Context, groupID int64, platform string) ([]Account, error)
	ListSchedulableByPlatforms(ctx context.Context, platforms []string) ([]Account, error)
	ListSchedulableByGroupIDAndPlatforms(ctx context.Context, groupID int64, platforms []string) ([]Account, error)

	SetRateLimited(ctx context.Context, id int64, resetAt time.Time) error
	SetOverloaded(ctx context.Context, id int64, until time.Time) error
	SetTempUnschedulable(ctx context.Context, id int64, until time.Time, reason string) error
	ClearTempUnschedulable(ctx context.Context, id int64) error
	ClearRateLimit(ctx context.Context, id int64) error
	UpdateSessionWindow(ctx context.Context, id int64, start, end *time.Time, status string) error
	UpdateExtra(ctx context.Context, id int64, updates map[string]any) error
	BulkUpdate(ctx context.Context, ids []int64, updates AccountBulkUpdate) (int64, error)
}

// AccountBulkUpdate describes the fields that can be updated in a bulk operation.
// Nil pointers mean "do not change".
type AccountBulkUpdate struct {
	Name        *string
	ProxyID     *int64
	Concurrency *int
	Priority    *int
	Status      *string
	Credentials map[string]any
	Extra       map[string]any
}

// CreateAccountRequest 创建账号请求
type CreateAccountRequest struct {
	Name        string         `json:"name"`
	Platform    string         `json:"platform"`
	Type        string         `json:"type"`
	Credentials map[string]any `json:"credentials"`
	Extra       map[string]any `json:"extra"`
	ProxyID     *int64         `json:"proxy_id"`
	Concurrency int            `json:"concurrency"`
	Priority    int            `json:"priority"`
	GroupIDs    []int64        `json:"group_ids"`
}

// UpdateAccountRequest 更新账号请求
type UpdateAccountRequest struct {
	Name        *string         `json:"name"`
	Credentials *map[string]any `json:"credentials"`
	Extra       *map[string]any `json:"extra"`
	ProxyID     *int64          `json:"proxy_id"`
	Concurrency *int            `json:"concurrency"`
	Priority    *int            `json:"priority"`
	Status      *string         `json:"status"`
	GroupIDs    *[]int64        `json:"group_ids"`
}

// AccountService 账号管理服务
type AccountService struct {
	accountRepo AccountRepository
	groupRepo   GroupRepository
}

// NewAccountService 创建账号服务实例
func NewAccountService(accountRepo AccountRepository, groupRepo GroupRepository) *AccountService {
	return &AccountService{
		accountRepo: accountRepo,
		groupRepo:   groupRepo,
	}
}

// Create 创建账号
func (s *AccountService) Create(ctx context.Context, req CreateAccountRequest) (*Account, error) {
	// 验证分组是否存在（如果指定了分组）
	if len(req.GroupIDs) > 0 {
		for _, groupID := range req.GroupIDs {
			_, err := s.groupRepo.GetByID(ctx, groupID)
			if err != nil {
				return nil, fmt.Errorf("get group: %w", err)
			}
		}
	}

	// 创建账号
	account := &Account{
		Name:        req.Name,
		Platform:    req.Platform,
		Type:        req.Type,
		Credentials: req.Credentials,
		Extra:       req.Extra,
		ProxyID:     req.ProxyID,
		Concurrency: req.Concurrency,
		Priority:    req.Priority,
		Status:      StatusActive,
	}

	if err := s.accountRepo.Create(ctx, account); err != nil {
		return nil, fmt.Errorf("create account: %w", err)
	}

	// 绑定分组
	if len(req.GroupIDs) > 0 {
		if err := s.accountRepo.BindGroups(ctx, account.ID, req.GroupIDs); err != nil {
			return nil, fmt.Errorf("bind groups: %w", err)
		}
	}

	return account, nil
}

// GetByID 根据ID获取账号
func (s *AccountService) GetByID(ctx context.Context, id int64) (*Account, error) {
	account, err := s.accountRepo.GetByID(ctx, id)
	if err != nil {
		return nil, fmt.Errorf("get account: %w", err)
	}
	return account, nil
}

// List 获取账号列表
func (s *AccountService) List(ctx context.Context, params pagination.PaginationParams) ([]Account, *pagination.PaginationResult, error) {
	accounts, pagination, err := s.accountRepo.List(ctx, params)
	if err != nil {
		return nil, nil, fmt.Errorf("list accounts: %w", err)
	}
	return accounts, pagination, nil
}

// ListByPlatform 根据平台获取账号列表
func (s *AccountService) ListByPlatform(ctx context.Context, platform string) ([]Account, error) {
	accounts, err := s.accountRepo.ListByPlatform(ctx, platform)
	if err != nil {
		return nil, fmt.Errorf("list accounts by platform: %w", err)
	}
	return accounts, nil
}

// ListByGroup 根据分组获取账号列表
func (s *AccountService) ListByGroup(ctx context.Context, groupID int64) ([]Account, error) {
	accounts, err := s.accountRepo.ListByGroup(ctx, groupID)
	if err != nil {
		return nil, fmt.Errorf("list accounts by group: %w", err)
	}
	return accounts, nil
}

// Update 更新账号
func (s *AccountService) Update(ctx context.Context, id int64, req UpdateAccountRequest) (*Account, error) {
	account, err := s.accountRepo.GetByID(ctx, id)
	if err != nil {
		return nil, fmt.Errorf("get account: %w", err)
	}

	// 更新字段
	if req.Name != nil {
		account.Name = *req.Name
	}

	if req.Credentials != nil {
		account.Credentials = *req.Credentials
	}

	if req.Extra != nil {
		account.Extra = *req.Extra
	}

	if req.ProxyID != nil {
		account.ProxyID = req.ProxyID
	}

	if req.Concurrency != nil {
		account.Concurrency = *req.Concurrency
	}

	if req.Priority != nil {
		account.Priority = *req.Priority
	}

	if req.Status != nil {
		account.Status = *req.Status
	}

	// 先验证分组是否存在（在任何写操作之前）
	if req.GroupIDs != nil {
		for _, groupID := range *req.GroupIDs {
			_, err := s.groupRepo.GetByID(ctx, groupID)
			if err != nil {
				return nil, fmt.Errorf("get group: %w", err)
			}
		}
	}

	// 执行更新
	if err := s.accountRepo.Update(ctx, account); err != nil {
		return nil, fmt.Errorf("update account: %w", err)
	}

	// 绑定分组
	if req.GroupIDs != nil {
		if err := s.accountRepo.BindGroups(ctx, account.ID, *req.GroupIDs); err != nil {
			return nil, fmt.Errorf("bind groups: %w", err)
		}
	}

	return account, nil
}

// Delete 删除账号
// 优化：使用 ExistsByID 替代 GetByID 进行存在性检查，
// 避免加载完整账号对象及其关联数据，提升删除操作的性能
func (s *AccountService) Delete(ctx context.Context, id int64) error {
	// 使用轻量级的存在性检查，而非加载完整账号对象
	exists, err := s.accountRepo.ExistsByID(ctx, id)
	if err != nil {
		return fmt.Errorf("check account: %w", err)
	}
	// 明确返回账号不存在错误，便于调用方区分错误类型
	if !exists {
		return ErrAccountNotFound
	}

	if err := s.accountRepo.Delete(ctx, id); err != nil {
		return fmt.Errorf("delete account: %w", err)
	}

	return nil
}

// UpdateStatus 更新账号状态
func (s *AccountService) UpdateStatus(ctx context.Context, id int64, status string, errorMessage string) error {
	account, err := s.accountRepo.GetByID(ctx, id)
	if err != nil {
		return fmt.Errorf("get account: %w", err)
	}

	account.Status = status
	account.ErrorMessage = errorMessage

	if err := s.accountRepo.Update(ctx, account); err != nil {
		return fmt.Errorf("update account: %w", err)
	}

	return nil
}

// UpdateLastUsed 更新最后使用时间
func (s *AccountService) UpdateLastUsed(ctx context.Context, id int64) error {
	if err := s.accountRepo.UpdateLastUsed(ctx, id); err != nil {
		return fmt.Errorf("update last used: %w", err)
	}
	return nil
}

// GetCredential 获取账号凭证（安全访问）
func (s *AccountService) GetCredential(ctx context.Context, id int64, key string) (string, error) {
	account, err := s.accountRepo.GetByID(ctx, id)
	if err != nil {
		return "", fmt.Errorf("get account: %w", err)
	}

	return account.GetCredential(key), nil
}

// TestCredentials 测试账号凭证是否有效（需要实现具体平台的测试逻辑）
func (s *AccountService) TestCredentials(ctx context.Context, id int64) error {
	account, err := s.accountRepo.GetByID(ctx, id)
	if err != nil {
		return fmt.Errorf("get account: %w", err)
	}

	// 根据平台执行不同的测试逻辑
	switch account.Platform {
	case PlatformAnthropic:
		// TODO: 测试Anthropic API凭证
		return nil
	case PlatformOpenAI:
		// TODO: 测试OpenAI API凭证
		return nil
	case PlatformGemini:
		// TODO: 测试Gemini API凭证
		return nil
	default:
		return fmt.Errorf("unsupported platform: %s", account.Platform)
	}
}
