package service

import (
	"context"
	"errors"

	"github.com/Tencent/WeKnora/internal/accesspolicy"
	apperrors "github.com/Tencent/WeKnora/internal/errors"
	"github.com/Tencent/WeKnora/internal/types"
)

// PrepareAgentExecutionContext delegates only live bindings owned by the
// authorized Agent's creator. The caller's publication snapshot stays intact.
func (s *customAgentService) PrepareAgentExecutionContext(ctx context.Context, id string) (context.Context, error) {
	prepared, err := s.prepareAgentExecution(ctx, id, map[string]bool{}, map[string]bool{})
	if errors.Is(err, ErrAgentNotFound) {
		return ctx, apperrors.NewNotFoundError("Agent 已删除或无权使用")
	}
	if err != nil {
		return ctx, err
	}
	return prepared, nil
}

func (s *customAgentService) prepareAgentExecution(ctx context.Context, id string, visiting, visited map[string]bool) (context.Context, error) {
	if visiting[id] {
		return ctx, apperrors.NewBadRequestError("Agent 依赖存在循环或层级过多，请调整融合配置")
	}
	if visited[id] {
		return ctx, nil
	}
	if len(visited) >= 64 {
		return ctx, apperrors.NewBadRequestError("Agent 依赖存在循环或层级过多，请调整融合配置")
	}
	agent, err := s.GetAgentByID(ctx, id)
	if err != nil {
		return ctx, err
	}
	if agent == nil || !agent.Enabled || !accesspolicy.Allowed(ctx, "agents.read") {
		return ctx, apperrors.NewForbiddenError("Agent 已停用或无权使用")
	}
	if guard, ok := s.repo.(interface {
		CheckDigitalHumanAgentExecution(context.Context, *types.CustomAgent) error
	}); ok {
		if err := guard.CheckDigitalHumanAgentExecution(ctx, agent); err != nil {
			return ctx, err
		}
	}
	visiting[id] = true
	defer delete(visiting, id)
	visited[id] = true
	if agent.Config.KBSelectionMode == "selected" && len(agent.Config.KnowledgeBases) > 0 && s.kbService != nil {
		for _, kbID := range agent.Config.KnowledgeBases {
			kb, err := s.kbService.GetRepository().GetKnowledgeBaseByIDAndTenant(ctx, kbID, agent.TenantID)
			if err != nil || kb == nil {
				continue
			}
			if kb.CreatorID != "" && kb.CreatorID == agent.CreatedBy && kb.VersionState == "" {
				ctx = accesspolicy.WithExecutionDependency(ctx, agent.TenantID, "knowledge", kb.ID, kb.CreatorID)
			}
		}
	}
	for _, fusionID := range agent.Config.FusionAgentIDs {
		child, err := s.repo.GetAgentByID(ctx, fusionID, agent.TenantID)
		if err != nil || child == nil {
			return ctx, apperrors.NewForbiddenError("融合 Agent 已删除或不可用")
		}
		if child.CreatedBy != "" && child.CreatedBy == agent.CreatedBy {
			ctx = accesspolicy.WithExecutionDependency(ctx, agent.TenantID, "agents", child.ID, child.CreatedBy)
		}
		ctx, err = s.prepareAgentExecution(ctx, fusionID, visiting, visited)
		if err != nil {
			return ctx, err
		}
	}
	return ctx, nil
}