// homepage-build：把 homepage/ 源（落地页 + 定价页 + 文档 md）构建为纯静态站点 homepage/dist/。
// 产物可直接部署到任意静态托管（nginx/Pages）——官网与后端二进制彻底解耦。
// 用法: go run . [-src homepage] [-out homepage/dist]
package main

import (
	"encoding/json"
	"flag"
	"fmt"
	"html/template"
	"os"
	"path/filepath"
	"regexp"
	"strings"

	"github.com/yuin/goldmark"
	"github.com/yuin/goldmark/extension"
	gmhtml "github.com/yuin/goldmark/renderer/html"
)

type PageDef struct {
	File    string `json:"file"`
	Slug    string `json:"slug"`
	Title   string `json:"title"`
	Updated string `json:"updated,omitempty"`
	Hidden  bool   `json:"hidden,omitempty"`
}
type GroupDef struct {
	Name  string    `json:"name"`
	Pages []PageDef `json:"pages"`
}
type Manifest struct {
	ProductVersion string     `json:"productVersion"`
	Groups         []GroupDef `json:"groups"`
}
type TocItem struct {
	ID    string
	Level int
	Text  string
}
type SearchEntry struct {
	Slug, Title, Group, Text string
}
type NavLink struct {
	Slug, Title string
}
type Page struct {
	Slug, Title, Group, Updated string
	HTML                        template.HTML
	TOC                         []TocItem
	Prev, Next                  *NavLink
}

var (
	hRe     = regexp.MustCompile(`(?s)<(h[23])>(.*?)</h[23]>`)
	tagRe   = regexp.MustCompile(`<[^>]+>`)
	mdNoise = regexp.MustCompile("(?s)```.*?```|`[^`]*`|!\\[[^\\]]*\\]\\([^)]*\\)|\\[[^\\]]*\\]\\([^)]*\\)|[#>*_\\-|]+")
)

func injectHeadingIDs(html string) (string, []TocItem) {
	var toc []TocItem
	counter := 0
	out := hRe.ReplaceAllStringFunc(html, func(m string) string {
		sub := hRe.FindStringSubmatch(m)
		tag, inner := sub[1], sub[2]
		counter++
		id := fmt.Sprintf("sec-%d", counter)
		text := strings.TrimSpace(tagRe.ReplaceAllString(inner, ""))
		level := 2
		if tag == "h3" {
			level = 3
		}
		toc = append(toc, TocItem{ID: id, Level: level, Text: text})
		return fmt.Sprintf(`<%s id="%s">%s</%s>`, tag, id, inner, tag)
	})
	return out, toc
}

func plainText(src string) string {
	s := mdNoise.ReplaceAllString(src, " ")
	s = strings.Join(strings.Fields(s), " ")
	if len(s) > 6000 {
		s = s[:6000]
	}
	return s
}

func must(err error, what string) {
	if err != nil {
		fmt.Fprintf(os.Stderr, "[homepage-build] %s: %v\n", what, err)
		os.Exit(1)
	}
}

func writeFile(path string, content []byte) {
	must(os.MkdirAll(filepath.Dir(path), 0o755), "mkdir "+path)
	must(os.WriteFile(path, content, 0o644), "write "+path)
	fmt.Println("[OK]", path)
}

// visibleManifest 返回去掉 hidden 页的分组清单：模板侧栏、上/下一页、搜索索引都只含可见页。
// Logan.Li
func visibleManifest(m Manifest) Manifest {
	vm := Manifest{ProductVersion: m.ProductVersion}
	for _, g := range m.Groups {
		ng := GroupDef{Name: g.Name}
		for _, p := range g.Pages {
			if !p.Hidden {
				ng.Pages = append(ng.Pages, p)
			}
		}
		if len(ng.Pages) > 0 {
			vm.Groups = append(vm.Groups, ng)
		}
	}
	return vm
}

func main() {
	src := flag.String("src", "homepage", "源目录")
	out := flag.String("out", "homepage/dist", "产物目录")
	flag.Parse()

	// 幂等重建：清理上一轮生成的子目录（os.CopyFS 目标已存在会报错）
	for _, d := range []string{"site", "docs", "pricing", "home"} {
		must(os.RemoveAll(filepath.Join(*out, d)), "清理 "+d)
	}

	// 1) 落地页 + 别名 + 可选单页：纯 HTML 直接拷贝
	raw, err := os.ReadFile(filepath.Join(*src, "index.html"))
	must(err, "读 index.html")
	writeFile(filepath.Join(*out, "index.html"), raw)
	// /home 别名：对齐 nginx try_files $uri/index.html，GUI openExternal("/home") 依赖它
	writeFile(filepath.Join(*out, "home", "index.html"), raw)

	// 可选单页（pricing / terms / license）：根 <name>.html + <name>/index.html
	// （对齐 nginx location = /pricing|/license → 目录内 index；纯静态服务器上 /pricing/ 亦为 200）// Logan.Li
	for _, name := range []string{"pricing.html", "terms.html", "license.html"} {
		b, e := os.ReadFile(filepath.Join(*src, name))
		if e != nil {
			continue
		}
		writeFile(filepath.Join(*out, name), b)
		writeFile(filepath.Join(*out, strings.TrimSuffix(name, ".html"), "index.html"), b)
	}
	// 站点资源：落地页/定价页引用 /site/assets/*
	siteAssets := filepath.Join(*src, "assets")
	if st, _ := os.Stat(siteAssets); st != nil {
		must(os.CopyFS(filepath.Join(*out, "site", "assets"), os.DirFS(siteAssets)), "拷 site assets")
		fmt.Println("[OK]", filepath.Join(*out, "site", "assets"))
	}

	// 2) 文档：manifest → goldmark 渲染 → docs.html 模板（Go html/template）
	mraw, err := os.ReadFile(filepath.Join(*src, "content", "manifest.json"))
	must(err, "读 manifest")
	var manifest Manifest
	must(json.Unmarshal(mraw, &manifest), "解析 manifest")
	vis := visibleManifest(manifest)

	tplRaw, err := os.ReadFile(filepath.Join(*src, "docs.html"))
	must(err, "读 docs.html")
	tpl, err := template.New("doc").Parse(string(tplRaw))
	must(err, "解析 docs 模板")
	md := goldmark.New(goldmark.WithExtensions(extension.Table, extension.Strikethrough, extension.TaskList), goldmark.WithRendererOptions(gmhtml.WithHardWraps()))

	// 可见页顺序（侧栏 / 上下一页 / 搜索）
	var order []string
	pages := map[string]*Page{}
	var search []SearchEntry
	var prev *NavLink
	for _, g := range vis.Groups {
		for _, def := range g.Pages {
			srcb, err := os.ReadFile(filepath.Join(*src, "content", def.File))
			must(err, "读文档 "+def.File)
			var buf strings.Builder
			must(md.Convert(srcb, &buf), "渲染 "+def.File)
			body, toc := injectHeadingIDs(buf.String())
			p := &Page{Slug: def.Slug, Title: def.Title, Group: g.Name, Updated: def.Updated, HTML: template.HTML(body), TOC: toc, Prev: prev}
			pages[def.Slug] = p
			order = append(order, def.Slug)
			prev = &NavLink{Slug: def.Slug, Title: def.Title}
			search = append(search, SearchEntry{Slug: def.Slug, Title: def.Title, Group: g.Name, Text: plainText(string(srcb))})
		}
	}
	for i, slug := range order {
		if i+1 < len(order) {
			n := pages[order[i+1]]
			pages[slug].Next = &NavLink{Slug: n.Slug, Title: n.Title}
		}
	}

	render := func(p *Page) []byte {
		var sb strings.Builder
		must(tpl.Execute(&sb, map[string]any{"Manifest": vis, "Page": p, "TOC": p.TOC, "Content": p.HTML}), "渲染模板 "+p.Slug)
		return []byte(sb.String())
	}
	// /docs/ 首页 = 第一篇（静态站无重定向，直接渲染）
	writeFile(filepath.Join(*out, "docs", "index.html"), render(pages[order[0]]))
	for _, slug := range order {
		writeFile(filepath.Join(*out, "docs", slug, "index.html"), render(pages[slug]))
	}
	// hidden 页：仍渲染为独立页面（不进侧栏/导航/搜索），供 /docs/<slug> 直达
	for _, g := range manifest.Groups {
		for _, def := range g.Pages {
			if !def.Hidden {
				continue
			}
			srcb, err := os.ReadFile(filepath.Join(*src, "content", def.File))
			must(err, "读隐藏文档 "+def.File)
			var buf strings.Builder
			must(md.Convert(srcb, &buf), "渲染 "+def.File)
			body, toc := injectHeadingIDs(buf.String())
			p := &Page{Slug: def.Slug, Title: def.Title, Group: g.Name, Updated: def.Updated, HTML: template.HTML(body), TOC: toc}
			writeFile(filepath.Join(*out, "docs", def.Slug, "index.html"), render(p))
		}
	}
	sj, _ := json.Marshal(search)
	writeFile(filepath.Join(*out, "docs", "search-data.json"), sj)

	// docs assets（模板引用 /docs/assets/*）
	da := filepath.Join(*src, "docs-assets")
	if st, _ := os.Stat(da); st != nil {
		must(os.CopyFS(filepath.Join(*out, "docs", "assets"), os.DirFS(da)), "拷 docs assets")
		fmt.Println("[OK]", filepath.Join(*out, "docs", "assets"))
	}

	fmt.Printf("[DONE] 落地页 + %d 页文档（+隐藏页）→ %s（纯静态，可部署任意域名）\n", len(order), *out)
}