package search

import (
	"strings"

	"gorm.io/gorm"
	"senlinai-agent/backend/internal/models"
)

type Service struct {
	db *gorm.DB
}

const maxSearchResults = 50

// SearchResultDTO 是搜索接口的稳定结果，所有关联均使用公开 identity。
type SearchResultDTO struct {
	Type      string `json:"type"`
	ID        string `json:"id"`
	ProjectID string `json:"projectId"`
	Title     string `json:"title"`
	Snippet   string `json:"snippet"`
}

func NewService(databases ...*gorm.DB) *Service {
	var database *gorm.DB
	if len(databases) > 0 {
		database = databases[0]
	}
	return &Service{db: database}
}

func (s *Service) database() *gorm.DB {
	if s.db != nil {
		return s.db
	}
	return models.DBService
}

func (s *Service) Search(userID uint, query string) ([]SearchResultDTO, error) {
	query = strings.TrimSpace(query)
	if query == "" {
		return []SearchResultDTO{}, nil
	}
	if s.database().Dialector.Name() == "postgres" {
		return s.searchPostgres(userID, query)
	}

	like := containsPattern(query)
	results := []SearchResultDTO{}
	var projects []models.SenlinAgentProject
	if err := s.database().Where("owner_id = ? AND (name LIKE ? ESCAPE '!' OR description LIKE ? ESCAPE '!')", userID, like, like).Limit(maxSearchResults).Find(&projects).Error; err != nil {
		return nil, err
	}
	for _, project := range projects {
		results = append(results, SearchResultDTO{Type: "project", ID: project.Identity, ProjectID: project.Identity, Title: project.Name, Snippet: project.Description})
	}

	var tasks []models.SenlinAgentTask
	if err := s.database().Select("senlin_agent_tasks.*").Joins("JOIN senlin_agent_projects ON senlin_agent_projects.id = senlin_agent_tasks.project_id").
		Where("(senlin_agent_projects.owner_id = ? OR senlin_agent_tasks.assignee_id = ?) AND (senlin_agent_tasks.title LIKE ? ESCAPE '!' OR senlin_agent_tasks.description LIKE ? ESCAPE '!')", userID, userID, like, like).
		Limit(maxSearchResults).
		Find(&tasks).Error; err != nil {
		return nil, err
	}
	for _, task := range tasks {
		results = append(results, SearchResultDTO{Type: "task", ID: task.Identity, ProjectID: task.ProjectIdentity, Title: task.Title, Snippet: task.Description})
	}

	var notes []models.SenlinAgentNote
	if err := s.database().Select("senlin_agent_notes.*").Joins("JOIN senlin_agent_projects ON senlin_agent_projects.id = senlin_agent_notes.project_id").
		Where(`(senlin_agent_projects.owner_id = ? OR EXISTS (
			SELECT 1 FROM senlin_agent_task_shares
			JOIN senlin_agent_tasks ON senlin_agent_tasks.id = senlin_agent_task_shares.task_id
			WHERE senlin_agent_task_shares.object_type = 'note'
			  AND senlin_agent_task_shares.object_id = senlin_agent_notes.id
			  AND senlin_agent_tasks.project_id = senlin_agent_notes.project_id
			  AND senlin_agent_tasks.assignee_id = ?
		)) AND (senlin_agent_notes.title LIKE ? ESCAPE '!' OR senlin_agent_notes.markdown LIKE ? ESCAPE '!')`, userID, userID, like, like).
		Limit(maxSearchResults).
		Find(&notes).Error; err != nil {
		return nil, err
	}
	for _, note := range notes {
		results = append(results, SearchResultDTO{Type: "note", ID: note.Identity, ProjectID: note.ProjectIdentity, Title: note.Title, Snippet: note.Markdown})
	}
	if len(results) > maxSearchResults {
		results = results[:maxSearchResults]
	}
	return results, nil
}

func (s *Service) searchPostgres(userID uint, query string) ([]SearchResultDTO, error) {
	var results []SearchResultDTO
	like := containsPattern(query)
	err := s.database().Raw(`
		SELECT 'project' AS type, p.identity AS id, p.identity AS project_id, p.name AS title, p.description AS snippet
		FROM senlin_agent_projects p
		WHERE p.owner_id = ?
		  AND (coalesce(p.name, '') ILIKE ? ESCAPE '!' OR coalesce(p.description, '') ILIKE ? ESCAPE '!')
		UNION ALL
		SELECT 'task' AS type, t.identity AS id, p.identity AS project_id, t.title, t.description AS snippet
		FROM senlin_agent_tasks t
		JOIN senlin_agent_projects p ON p.id = t.project_id
		WHERE (p.owner_id = ? OR t.assignee_id = ?)
		  AND (coalesce(t.title, '') ILIKE ? ESCAPE '!' OR coalesce(t.description, '') ILIKE ? ESCAPE '!')
		UNION ALL
		SELECT 'note' AS type, n.identity AS id, p.identity AS project_id, n.title, n.markdown AS snippet
		FROM senlin_agent_notes n
		JOIN senlin_agent_projects p ON p.id = n.project_id
		WHERE (p.owner_id = ? OR EXISTS (
			SELECT 1 FROM senlin_agent_task_shares ts
			JOIN senlin_agent_tasks t ON t.id = ts.task_id
			WHERE ts.object_type = 'note'
			  AND ts.object_id = n.id
			  AND t.project_id = n.project_id
			  AND t.assignee_id = ?
		))
		  AND (coalesce(n.title, '') ILIKE ? ESCAPE '!' OR coalesce(n.markdown, '') ILIKE ? ESCAPE '!')
		LIMIT ?
	`, userID, like, like, userID, userID, like, like, userID, userID, like, like, maxSearchResults).Scan(&results).Error
	return results, err
}

func containsPattern(query string) string {
	escaped := strings.NewReplacer("!", "!!", "%", "!%", "_", "!_").Replace(query)
	return "%" + escaped + "%"
}