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，返回图和未解析的悬空链接列表
func BuildGraph(files []*vault.FileMeta) (*Graph, []*UnresolvedLink) {
	g := &Graph{}
	unresolved := make([]*UnresolvedLink, 0)

	// 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,
				Provenance: "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,
				Provenance: "entity",
			})
		}
	}

	// 创建 wikilink 边（文件间链接），未匹配的记入悬空链接列表
	for _, n := range g.Nodes {
		for _, link := range n.Wikilinks {
			target, prov := ResolveWikilink(g.Nodes, link)
			if target == nil {
				unresolved = append(unresolved, &UnresolvedLink{
					FromNode: n.ID, LinkText: link, NameTail: NameTail(link),
				})
				continue
			}
			g.Edges = append(g.Edges, &Edge{
				FromNode:   n.ID,
				ToNode:     target.ID,
				Relation:   "wikilink",
				Label:      link,
				Provenance: prov,
			})
		}
	}

	return g, unresolved
}

// ResolveWikilink 解析 wikilink 目标，返回 (目标节点, provenance)。
// exact = 标题/文件名精确；fuzzy = 标题包含。纯内存版，规则与 index 包 DB 版一致。
func ResolveWikilink(nodes []*Node, link string) (*Node, string) {
	// 去锚点：[[标题|别名]] 取标题部分
	if idx := strings.Index(link, "|"); idx >= 0 {
		link = link[:idx]
	}
	var fuzzy *Node
	for _, node := range nodes {
		if node.Title == link {
			return node, "exact"
		}
		// 匹配文件名（去 .md 和编号前缀），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")
		if dash := strings.Index(base, "-"); dash >= 0 {
			base = base[dash+1:]
		}
		if base == link {
			return node, "exact"
		}
		if fuzzy == nil && strings.Contains(node.Title, link) {
			fuzzy = node
		}
	}
	if fuzzy != nil {
		return fuzzy, "fuzzy"
	}
	return nil, ""
}

// NameTail 取 link 尾部用于悬空链接重试匹配（去锚点修饰）
func NameTail(link string) string {
	if idx := strings.Index(link, "|"); idx >= 0 {
		link = link[:idx]
	}
	return link
}