package server

import (
	"context"
	"fmt"
	"net/http"
	"strconv"
	"strings"

	"chat-agent-system/internal/projectworkflow"
)

// filterLineageEdges 丢掉不属于该项目，或任一端文档对当前主体不可见的边。
// 不可见端整行省略，避免通过 ID、标题或数量泄漏。
func filterLineageEdges(rows []*projectworkflow.DocumentLineage, projectID int64, visible func(docID string) bool) []*projectworkflow.DocumentLineage {
	out := make([]*projectworkflow.DocumentLineage, 0, len(rows))
	for _, row := range rows {
		if row == nil || row.ProjectID != projectID {
			continue
		}
		if visible == nil || !visible(row.DownstreamDocID) || !visible(row.UpstreamDocID) {
			continue
		}
		out = append(out, row)
	}
	return out
}

func writeEmptyLineage(w http.ResponseWriter) {
	writeJSONResponse(w, http.StatusOK, []*projectworkflow.DocumentLineage{})
}

// lineageDocVisible 判断 docID 是否属于 projectID，且当前用户可查看其任务。
// 无法证明归属时返回 false，调用方应给出与“没有血缘”相同的空结果。
func (s *Server) lineageDocVisible(ctx context.Context, projectID, userID int64, docID string) bool {
	docID = strings.TrimSpace(docID)
	if s == nil || projectID <= 0 || docID == "" {
		return false
	}
	taskKey, placed, ok := s.lineageDocPlacement(ctx, projectID, docID)
	if !ok || !placed {
		return false
	}
	if taskKey == "" {
		return true
	}
	return s.allowWorkflowDocTaskAccess(ctx, projectID, userID, taskKey)
}

func (s *Server) lineageDocPlacement(ctx context.Context, projectID int64, docID string) (taskKey string, placed bool, ok bool) {
	if s.gov() != nil {
		doc, err := s.gov().GetDocument(ctx, docID)
		if err != nil {
			if status, mapped := domainHTTPStatus(err); !(mapped && status == http.StatusNotFound) {
				return "", false, false
			}
		}
		if err == nil && doc != nil {
			if doc.ProjectID != projectID {
				return "", false, true
			}
			return doc.TaskKey, true, true
		}
	}
	if pid, task, parsed := parseCanonicalWorkflowDocID(docID); parsed {
		if pid != projectID {
			return "", false, true
		}
		return task, true, true
	}
	if pid, parsed := parseHyphenProjectDocID(docID); parsed {
		if pid != projectID {
			return "", false, true
		}
		return "", true, true
	}
	return "", false, true
}

func parseHyphenProjectDocID(docID string) (int64, bool) {
	const prefix = "doc-proj"
	if !strings.HasPrefix(docID, prefix) {
		return 0, false
	}
	rest := strings.TrimPrefix(docID, prefix)
	idx := strings.IndexByte(rest, '-')
	if idx <= 0 || idx >= len(rest)-1 {
		return 0, false
	}
	projectID, err := strconv.ParseInt(rest[:idx], 10, 64)
	if err != nil || projectID <= 0 {
		return 0, false
	}
	return projectID, true
}

// lineageTestManagerAlias 仅在两种 test_manager 文档 ID 写法之间互换，不把任意空查询改写成别的文档。
func lineageTestManagerAlias(projectID int64, docID string) (string, bool) {
	canonical := fmt.Sprintf("doc_proj%d_test_manager", projectID)
	hyphen := fmt.Sprintf("doc-proj%d-test_manager", projectID)
	switch docID {
	case canonical:
		return hyphen, true
	case hyphen:
		return canonical, true
	default:
		return "", false
	}
}