package graph

import (
	"path/filepath"
	"strings"

	"github.com/aisim/kb-cli/internal/vault"
)

// BuildGraph 从文件元数据构建知识图谱
func BuildGraph(files []*vault.FileMeta) *Graph {
	g := &Graph{}

	// 标签/实体 -> 虚拟节点 ID 映射
	labelToID := make(map[string]int64)
	nextVirtualID := int64(1000000) // 虚拟节点从 1000000 开始

	getOrCreateVirtualNode := func(label string) int64 {
		if id, ok := labelToID[label]; ok {
			return id
		}
		id := nextVirtualID
		nextVirtualID++
		labelToID[label] = id
		return id
	}

	for i, f := range files {
		node := &Node{
			ID:        int64(i + 1),
			Path:      f.Path,
			Title:     f.Title,
			Section:   f.Section,
			Tags:      f.Tags,
			Entities:  f.Entities,
			Wikilinks: f.Wikilinks,
			Content:   f.Content,
		}
		g.Nodes = append(g.Nodes, node)

		// 创建 tag 边
		for _, tag := range f.Tags {
			virtualID := getOrCreateVirtualNode("tag:" + tag)
			g.Edges = append(g.Edges, &Edge{
				FromNode: node.ID,
				ToNode:   virtualID,
				Relation: "tag",
				Label:    tag,
			})
		}

		// 创建 entity 边
		for _, entity := range f.Entities {
			virtualID := getOrCreateVirtualNode("entity:" + entity)
			g.Edges = append(g.Edges, &Edge{
				FromNode: node.ID,
				ToNode:   virtualID,
				Relation: "entity",
				Label:    entity,
			})
		}
	}

	// 创建 wikilink 边（文件间链接）
	pathToID := make(map[string]int64)
	for _, n := range g.Nodes {
		pathToID[n.Path] = n.ID
	}

	for _, n := range g.Nodes {
		for _, link := range n.Wikilinks {
			// 尝试匹配目标文件（模糊匹配：链接文本可能只是标题的一部分）
			for _, target := range g.Nodes {
				if matchesWikilink(target, link) {
					g.Edges = append(g.Edges, &Edge{
						FromNode: n.ID,
						ToNode:   target.ID,
						Relation: "wikilink",
						Label:    link,
					})
					break
				}
			}
		}
	}

	return g
}

// matchesWikilink 检查文件是否匹配 wikilink
func matchesWikilink(node *Node, link string) bool {
	// 精确匹配标题
	if node.Title == link {
		return true
	}
	// 匹配文件名（不含扩展名和编号前缀）
	// 例如：[[充装规格配置]] 匹配 "知识/002-充装规格配置.md"
	base := filepath.Base(node.Path)
	base = strings.TrimSuffix(base, ".md")
	// 去掉编号前缀（如 "002-"）
	if idx := strings.Index(base, "-"); idx >= 0 {
		base = base[idx+1:]
	}
	return base == link || node.Title == link
}