package services

import (
	"fmt"
	"strings"
	"time"

	"lokistack/models"
	"lokistack/repository"
)

func ListLogPolicyGroups() []models.LogPolicyGroup {
	db := repository.GetDB()
	db.RLock()
	defer db.RUnlock()
	groups := make([]models.LogPolicyGroup, len(db.LogPolicyGroups))
	for i, group := range db.LogPolicyGroups {
		groups[i] = group
		groups[i].UserIDs = append([]uint(nil), group.UserIDs...)
		groups[i].Labels = make(map[string]string, len(group.Labels))
		for key, value := range group.Labels {
			groups[i].Labels[key] = value
		}
	}
	return groups
}

// AnyoneUserID 是 userIds 里的哨兵值，表示「所有人」(anyone / *)。
// 与 policyGroupAccess 的匹配逻辑、前端 ANYONE 常量保持一致。
const AnyoneUserID uint = 0

func validatePolicyGroup(db *repository.JsonDB, group models.LogPolicyGroup, excludeID uint) error {
	group.Name = strings.TrimSpace(group.Name)
	if group.Name == "" {
		return fmt.Errorf("策略组名称必填")
	}
	if group.SourceID == 0 {
		return fmt.Errorf("请选择数据源")
	}
	foundSource := false
	for _, source := range db.LogSources {
		if source.ID == group.SourceID {
			foundSource = true
			break
		}
	}
	if !foundSource {
		return fmt.Errorf("数据源不存在")
	}
	if len(group.UserIDs) == 0 {
		return fmt.Errorf("请选择至少一个用户")
	}
	for key := range group.Labels {
		if !ValidLogLabelName(key) {
			return fmt.Errorf("无效标签名: %s", key)
		}
	}
	seen := map[uint]bool{}
	for _, id := range group.UserIDs {
		if seen[id] {
			return fmt.Errorf("用户 ID 重复: %d", id)
		}
		seen[id] = true
		// AnyoneUserID(0) 是「所有人」哨兵，不对应真实用户记录，
		// 跳过存在性校验；但它必须独占，不能与其他具体用户混选。
		if id == AnyoneUserID {
			if len(group.UserIDs) > 1 {
				return fmt.Errorf("「所有人」不能与具体用户同时选择")
			}
			continue
		}
		found := false
		for _, user := range db.Users {
			if user.ID == id && user.Role != "admin" {
				found = true
				break
			}
		}
		if !found {
			return fmt.Errorf("用户 %d 不存在或不是普通用户", id)
		}
	}
	for _, other := range db.LogPolicyGroups {
		if other.ID == excludeID || other.SourceID != group.SourceID {
			continue
		}
		if other.Name == group.Name {
			return fmt.Errorf("此数据源已有同名策略组")
		}
		for _, id := range other.UserIDs {
			// AnyoneUserID(0) 是「所有人」哨兵，不是真实用户，
			// 允许多个策略组同时包含它（否则新建任何「所有人」策略组都会被这条冲突检查拒掉）
			if id == AnyoneUserID {
				continue
			}
			if seen[id] {
				return fmt.Errorf("用户 %d 已属于此数据源的另一个策略组", id)
			}
		}
	}
	return nil
}

// Group membership replaces legacy per-user grants for the same source.
func removeDirectGrants(db *repository.JsonDB, sourceID uint, userIDs []uint) {
	members := map[uint]bool{}
	for _, id := range userIDs {
		members[id] = true
	}
	for i := range db.LogSources {
		if db.LogSources[i].ID != sourceID {
			continue
		}
		kept := db.LogSources[i].Access[:0]
		for _, rule := range db.LogSources[i].Access {
			if !members[rule.UserID] {
				kept = append(kept, rule)
			}
		}
		db.LogSources[i].Access = kept
		return
	}
}

func CreateLogPolicyGroup(group models.LogPolicyGroup) (*models.LogPolicyGroup, error) {
	db := repository.GetDB()
	id := db.NextID("logPolicyGroups")
	db.Lock()
	defer db.Unlock()
	if err := validatePolicyGroup(db, group, 0); err != nil {
		return nil, err
	}
	group.ID = id
	group.Name = strings.TrimSpace(group.Name)
	group.CreatedAt = time.Now()
	group.UpdatedAt = group.CreatedAt
	removeDirectGrants(db, group.SourceID, group.UserIDs)
	db.LogPolicyGroups = append(db.LogPolicyGroups, group)
	db.RequestSave()
	return &group, nil
}

func UpdateLogPolicyGroup(id uint, group models.LogPolicyGroup) (*models.LogPolicyGroup, error) {
	db := repository.GetDB()
	db.Lock()
	defer db.Unlock()
	for i := range db.LogPolicyGroups {
		if db.LogPolicyGroups[i].ID != id {
			continue
		}
		if err := validatePolicyGroup(db, group, id); err != nil {
			return nil, err
		}
		group.ID = id
		group.Name = strings.TrimSpace(group.Name)
		group.CreatedAt = db.LogPolicyGroups[i].CreatedAt
		group.UpdatedAt = time.Now()
		removeDirectGrants(db, group.SourceID, group.UserIDs)
		db.LogPolicyGroups[i] = group
		db.RequestSave()
		return &group, nil
	}
	return nil, fmt.Errorf("策略组不存在")
}

func DeleteLogPolicyGroup(id uint) error {
	db := repository.GetDB()
	db.Lock()
	defer db.Unlock()
	for i := range db.LogPolicyGroups {
		if db.LogPolicyGroups[i].ID == id {
			db.LogPolicyGroups = append(db.LogPolicyGroups[:i], db.LogPolicyGroups[i+1:]...)
			db.RequestSave()
			return nil
		}
	}
	return fmt.Errorf("策略组不存在")
}

func policyGroupAccess(groups []models.LogPolicyGroup, sourceID, userID uint) *models.LogSourceAccess {
	for _, group := range groups {
		if group.SourceID != sourceID {
			continue
		}
		for _, id := range group.UserIDs {
			// 0 是哨兵值：表示「所有人」(anyone / *)，匹配任意用户。
			// 用于默认策略——让所有账号开箱即可查询业务命名空间。
			if id == 0 || id == userID {
				return &models.LogSourceAccess{UserID: userID, Labels: group.Labels}
			}
		}
	}
	return nil
}