// Package docs：用户文档骨架（嵌入 HTML，侧栏+正文密度对齐工作台）。
package docs

import (
	"embed"
	"net/http"
	"strings"

	"github.com/gin-gonic/gin"
)

//go:embed content assets template.html
var files embed.FS

type page struct {
	Slug  string
	Title string
	Body  string
}

var order = []page{
	{Slug: "install", Title: "安装与启动"},
	{Slug: "connect", Title: "连库入门"},
	{Slug: "workbench", Title: "工作台简介"},
	{Slug: "faq", Title: "常见问题"},
}

type Handler struct {
	tpl string
}

func New() *Handler {
	raw, err := files.ReadFile("template.html")
	if err != nil {
		panic("docs: template.html 缺失: " + err.Error())
	}
	return &Handler{tpl: string(raw)}
}

func (h *Handler) Register(r *gin.Engine) {
	r.GET("/docs", func(c *gin.Context) { c.Redirect(http.StatusFound, "/docs/install") })
	r.GET("/docs/:slug", h.Page)
	r.GET("/docs/assets/*file", h.Asset)
}

func (h *Handler) Page(c *gin.Context) {
	slug := c.Param("slug")
	bodyBytes, err := files.ReadFile("content/" + slug + ".html")
	if err != nil {
		c.Status(http.StatusNotFound)
		return
	}
	title := slug
	nav := strings.Builder{}
	for _, p := range order {
		cls := "nav-link"
		if p.Slug == slug {
			cls += " active"
			title = p.Title
		}
		nav.WriteString(`<a class="` + cls + `" href="/docs/` + p.Slug + `">` + p.Title + `</a>`)
	}
	html := h.tpl
	html = strings.ReplaceAll(html, "{{TITLE}}", title)
	html = strings.ReplaceAll(html, "{{NAV}}", nav.String())
	html = strings.ReplaceAll(html, "{{BODY}}", string(bodyBytes))
	c.Header("Content-Type", "text/html; charset=utf-8")
	c.Header("Cache-Control", "no-cache")
	_, _ = c.Writer.WriteString(html)
}

func (h *Handler) Asset(c *gin.Context) {
	name := strings.TrimPrefix(c.Param("file"), "/")
	if strings.Contains(name, "..") {
		c.Status(http.StatusBadRequest)
		return
	}
	data, err := files.ReadFile("assets/" + name)
	if err != nil {
		c.Status(http.StatusNotFound)
		return
	}
	ct := "application/octet-stream"
	if strings.HasSuffix(name, ".css") {
		ct = "text/css; charset=utf-8"
	}
	c.Header("Content-Type", ct)
	c.Data(http.StatusOK, ct, data)
}