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")
	ErrAccountNotInFallback = infraerrors.BadRequest("ACCOUNT_NOT_IN_FALLBACK", "account is not in proxy fallback state")
)

const AccountListGroupUngrouped int64 = -1
const AccountPrivacyModeUnsetFilter = "__unset__"

// OAuthRefreshPageOptions describes one bounded, cursor-stable scan of OAuth
// accounts. Candidate platforms are supplied by TokenRefreshService's refresher
// registry so repository eligibility cannot drift from registered providers.
type OAuthRefreshPageOptions struct {
	Platforms            []string
	AfterID              int64
	Limit                int
	ActiveOnly           bool
	IncludeSetupToken    bool
	RequireRefreshToken  bool
	ExcludeRetryCooldown bool
}

// OAuthRefreshCandidatePage keeps cursor metadata from the raw SQL ID page.
// Hydration may legitimately lose a concurrently deleted row, but callers can
// still advance past the raw page without truncating or duplicating the scan.
type OAuthRefreshCandidatePage struct {
	Accounts    []Account
	NextAfterID int64
	HasMore     bool
}

// OAuthRefreshCandidatePager is intentionally narrower than AccountRepository.
// Production refresh cycles fail closed when the repository does not implement
// this bounded contract instead of silently falling back to an unpaged scan.
type OAuthRefreshCandidatePager interface {
	ListOAuthRefreshCandidatePage(ctx context.Context, options OAuthRefreshPageOptions) (*OAuthRefreshCandidatePage, error)
}

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)
	// FindByExtraField 根据 extra 字段中的键值对查找账号
	FindByExtraField(ctx context.Context, key string, value any) ([]Account, error)
	// ListCRSAccountIDs returns a map of crs_account_id -> local account ID
	// for all accounts that have been synced from CRS.
	ListCRSAccountIDs(ctx context.Context) (map[string]int64, 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, groupID int64, privacyMode string) ([]Account, *pagination.PaginationResult, error)
	// ListAllWithFilters 返回符合过滤条件的全部账号（不分页），用于账号列表页
	// 计算 OpenAI 调度分数的过滤范围池。
	ListAllWithFilters(ctx context.Context, platform, accountType, status, search string, groupID int64, privacyMode string) ([]Account, 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
	ClearError(ctx context.Context, id int64) error
	SetSchedulable(ctx context.Context, id int64, schedulable bool) error
	AutoPauseExpiredAccounts(ctx context.Context, now time.Time) (int64, 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)
	ListSchedulableUngroupedByPlatform(ctx context.Context, platform string) ([]Account, error)
	ListSchedulableUngroupedByPlatforms(ctx context.Context, platforms []string) ([]Account, error)
	// ListModelAvailabilityCandidates returns accounts that are enabled by
	// persistent configuration (active + schedulable) for model-support
	// diagnosis. It deliberately does not filter transient runtime state such
	// as rate-limit, overload, temporary-unschedulable, or expiry windows.
	// When groupID is nil, includeGrouped controls whether the query scans all
	// matching accounts or only accounts without a group binding.
	ListModelAvailabilityCandidates(ctx context.Context, groupID *int64, platforms []string, includeGrouped bool) ([]Account, error)

	SetRateLimited(ctx context.Context, id int64, resetAt time.Time) error
	SetModelRateLimit(ctx context.Context, id int64, scope string, resetAt time.Time, reason ...string) 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
	ClearAntigravityQuotaScopes(ctx context.Context, id int64) error
	ClearModelRateLimits(ctx context.Context, id int64) error
	UpdateSessionWindow(ctx context.Context, id int64, start, end *time.Time, status string) error
	// UpdateSessionWindowEnd 仅更新 5h 窗口的结束时间，不动 start / status。
	// 用于 active poll 拿到新 ResetsAt 后回写，避免覆盖请求路径上记录的 status。
	UpdateSessionWindowEnd(ctx context.Context, id int64, end time.Time) error
	UpdateExtra(ctx context.Context, id int64, updates map[string]any) error
	BulkUpdate(ctx context.Context, ids []int64, updates AccountBulkUpdate) (int64, error)
	// IncrementQuotaUsed 原子递增 API Key 账号的配额用量（总/日/周）
	IncrementQuotaUsed(ctx context.Context, id int64, amount float64) error
	// ResetQuotaUsed 重置 API Key 账号所有维度的配额用量为 0
	ResetQuotaUsed(ctx context.Context, id int64) error
	// RevertProxyFallback 将账号的 proxy_id 切回 proxy_fallback_origin_id，并清空 origin 字段。
	// 仅当 proxy_fallback_origin_id IS NOT NULL 时更新，否则视为账号不存在（返回 ErrAccountNotFound）。
	RevertProxyFallback(ctx context.Context, accountID int64) error
	// ListShadowsByParent 返回指定父账号的影子账号；当前实现仅查 quota_dimension='spark'（唯一预设）。
	// ⚠️ 新增影子维度时：须更新此函数（或新增维度专用列举），并检查所有调用点（级联删除/一母一影校验/type 守卫），否则会静默漏掉新维度。
	ListShadowsByParent(ctx context.Context, parentID int64) ([]*Account, error)
}

type AccountDuplicateRepository interface {
	// CreateWithAccountGroups atomically persists an account, its exact group priorities,
	// and the scheduler outbox event for the new routing snapshot.
	CreateWithAccountGroups(ctx context.Context, account *Account, groups []AccountGroup) error
}

// AccountBillingSettingsRepository applies an admin edit without overwriting a
// rate_multiplier that a successful upstream probe synchronized after the edit
// form was loaded. A nil rateMultiplier means the request did not edit it.
type AccountBillingSettingsRepository interface {
	UpdateWithAccountBillingSettings(
		ctx context.Context,
		account *Account,
		probeEnabled *bool,
		rateSyncEnabled *bool,
		rateMultiplier *float64,
	) error
}

// AdminAccountRepository makes the account-duplication write capability an explicit
// construction dependency without forcing read-only gateway test doubles to implement it.
type AdminAccountRepository interface {
	AccountRepository
	AccountDuplicateRepository
	AccountBillingSettingsRepository
}

// 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
	RateMultiplier *float64
	LoadFactor     *int
	Status         *string
	Schedulable    *bool
	Credentials    map[string]any
	Extra          map[string]any
	ProbeEnabled   *bool
	// EnsureCodexFingerprintSeed asks the repository to atomically preserve an
	// existing valid Codex fingerprint seed or create one for eligible rows.
	EnsureCodexFingerprintSeed bool
}

// CreateAccountRequest 创建账号请求
type CreateAccountRequest struct {
	Name               string         `json:"name"`
	Notes              *string        `json:"notes"`
	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"`
	ExpiresAt          *time.Time     `json:"expires_at"`
	AutoPauseOnExpired *bool          `json:"auto_pause_on_expired"`
}

// UpdateAccountRequest 更新账号请求
type UpdateAccountRequest struct {
	Name               *string         `json:"name"`
	Notes              *string         `json:"notes"`
	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"`
	ExpiresAt          *time.Time      `json:"expires_at"`
	AutoPauseOnExpired *bool           `json:"auto_pause_on_expired"`
}

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

type groupExistenceBatchChecker interface {
	ExistsByIDs(ctx context.Context, ids []int64) (map[int64]bool, error)
}

// 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 {
		if err := s.validateGroupIDsExist(ctx, req.GroupIDs); err != nil {
			return nil, err
		}
	}

	// 创建账号
	account := &Account{
		Name:        req.Name,
		Notes:       normalizeAccountNotes(req.Notes),
		Platform:    req.Platform,
		Type:        req.Type,
		Credentials: SanitizeStoredCredentials(req.Platform, req.Credentials),
		Extra:       prepareCodexFingerprintExtraForCreate(req.Platform, req.Type, req.Extra),
		ProxyID:     req.ProxyID,
		Concurrency: req.Concurrency,
		Priority:    req.Priority,
		Status:      StatusActive,
		ExpiresAt:   req.ExpiresAt,
	}
	if req.AutoPauseOnExpired != nil {
		account.AutoPauseOnExpired = *req.AutoPauseOnExpired
	} else {
		account.AutoPauseOnExpired = true
	}

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

	// require_oauth_only 检查：apikey 类型账号不可加入限制分组
	if account.Type == AccountTypeAPIKey && len(req.GroupIDs) > 0 {
		for _, gid := range req.GroupIDs {
			g, err := s.groupRepo.GetByID(ctx, gid)
			if err != nil {
				return nil, err
			}
			if g.RequireOAuthOnly && (g.Platform == PlatformOpenAI || g.Platform == PlatformAntigravity || g.Platform == PlatformAnthropic || g.Platform == PlatformGemini || g.Platform == PlatformGrok) {
				return nil, fmt.Errorf("分组 [%s] 仅允许 OAuth 账号，apikey 类型账号无法加入", g.Name)
			}
		}
	}

	// 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.Notes != nil {
		account.Notes = normalizeAccountNotes(req.Notes)
	}

	if req.Credentials != nil {
		account.Credentials = SanitizeStoredCredentials(account.Platform, *req.Credentials)
	}

	if req.Extra != nil {
		extra := make(map[string]any, len(*req.Extra))
		for key, value := range *req.Extra {
			extra[key] = value
		}
		delete(extra, OllamaCloudUsageSessionExtraKey)
		delete(extra, OllamaCloudUsageAutoRefreshExtraKey)
		delete(extra, OllamaCloudUsageSnapshotExtraKey)
		account.Extra = prepareCodexFingerprintExtraForUpdate(account, extra)
	} else {
		account.Extra = prepareCodexFingerprintExtraForUpdate(account, account.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
	}
	if req.ExpiresAt != nil {
		account.ExpiresAt = req.ExpiresAt
	}
	if req.AutoPauseOnExpired != nil {
		account.AutoPauseOnExpired = *req.AutoPauseOnExpired
	}

	// 先验证分组是否存在（在任何写操作之前）
	if req.GroupIDs != nil {
		if err := s.validateGroupIDsExist(ctx, *req.GroupIDs); err != nil {
			return nil, err
		}
	}

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

	// require_oauth_only 检查
	if account.Type == AccountTypeAPIKey && req.GroupIDs != nil {
		for _, gid := range *req.GroupIDs {
			g, err := s.groupRepo.GetByID(ctx, gid)
			if err != nil {
				return nil, err
			}
			if g.RequireOAuthOnly && (g.Platform == PlatformOpenAI || g.Platform == PlatformAntigravity || g.Platform == PlatformAnthropic || g.Platform == PlatformGemini || g.Platform == PlatformGrok) {
				return nil, fmt.Errorf("分组 [%s] 仅允许 OAuth 账号，apikey 类型账号无法加入", g.Name)
			}
		}
	}

	// 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
	}

	// 注意:此处不级联删除 spark 影子账号。当前唯一的后台删除入口走 AdminService.DeleteAccount
	// (已 ListShadowsByParent 先删影子再删母)。本方法目前无删除调用方;若未来有调用方经此
	// 删除母账号,需在此补级联,否则会留下孤儿影子(外审第6轮 P3:当前不可达,记为残留)。
	if err := s.accountRepo.Delete(ctx, id); err != nil {
		return fmt.Errorf("delete account: %w", err)
	}

	return nil
}

func (s *AccountService) validateGroupIDsExist(ctx context.Context, groupIDs []int64) error {
	if len(groupIDs) == 0 {
		return nil
	}
	if s.groupRepo == nil {
		return fmt.Errorf("group repository not configured")
	}

	if batchChecker, ok := s.groupRepo.(groupExistenceBatchChecker); ok {
		existsByID, err := batchChecker.ExistsByIDs(ctx, groupIDs)
		if err != nil {
			return fmt.Errorf("check groups exists: %w", err)
		}
		for _, groupID := range groupIDs {
			if groupID <= 0 {
				return fmt.Errorf("get group: %w", ErrGroupNotFound)
			}
			if !existsByID[groupID] {
				return fmt.Errorf("get group: %w", ErrGroupNotFound)
			}
		}
		return nil
	}

	for _, groupID := range groupIDs {
		_, err := s.groupRepo.GetByID(ctx, groupID)
		if err != nil {
			return fmt.Errorf("get group: %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
	case PlatformGrok:
		// Grok OAuth credentials are validated via token exchange/refresh and request-path probes.
		return nil
	case PlatformKimi, PlatformZhipu, PlatformDeepseek:
		// 国产 OpenAI 兼容供应商：凭证为 API Key，实际可用性经余额/额度探测与转发路径验证。
		return nil
	default:
		return fmt.Errorf("unsupported platform: %s", account.Platform)
	}
}