package web

import (
	"embed"
	"io"
	"net/http"
	"regexp"
	"strings"
)

// The page about llmgw itself: what it is, how to install it, where to get
// it. It is the project's website, carried by every gateway so an operator
// has it where they already are, and served without a key like the landing
// page — it says nothing about this installation, only about the software.
//
// The same template renders the published website (Site), which differs in
// three ways: fonts from Google rather than from this binary, no link back to
// a gateway, and features on main marked as coming in the next release.

// proxyConfigs are the reverse proxy configurations the page shows. They are
// copies of deploy/proxy, which the release attaches; embed cannot reach
// outside this package, and TestAboutProxyConfigsMatchDeploy keeps the two
// the same.
//
//go:embed proxy
var proxyConfigs embed.FS

// AboutData is what the page is rendered with.
type AboutData struct {
	// Version is what this build calls itself; Release is the same when it is
	// a released version, and empty for a development build, which has no
	// files to download.
	Version, Release string
	// Download is where the release's files are, or for a development build
	// the proxy configurations on main.
	Download string
	// Date is the release date, when it is known. A binary does not know it.
	Date         string
	Caddy, Nginx string
	Site         bool
}

// releaseTag is a version the releases page has files for.
var releaseTag = regexp.MustCompile(`^v\d+\.\d+\.\d+$`)

const repoURL = "https://gitea.mynodes.xyz/ilker/llmgw"

// NewAboutData fills the page's data for a version.
func NewAboutData(version string) AboutData {
	d := AboutData{Version: version, Download: repoURL + "/raw/branch/main/deploy/proxy"}
	if releaseTag.MatchString(version) {
		d.Release = version
		d.Download = repoURL + "/releases/download/" + version
	}
	d.Caddy = proxyConfig("Caddyfile")
	d.Nginx = proxyConfig("nginx.conf")
	return d
}

func proxyConfig(name string) string {
	b, err := proxyConfigs.ReadFile("proxy/" + name)
	if err != nil {
		panic("web: the proxy configuration " + name + " is missing from the binary: " + err.Error())
	}
	return strings.TrimRight(string(b), "\n")
}

// RenderAbout writes the page, for the website's build as much as for About.
func RenderAbout(w io.Writer, d AboutData) error {
	return tmpl.ExecuteTemplate(w, "about", d)
}

// About serves the page at /about.
func About(version string) http.HandlerFunc {
	d := NewAboutData(version)
	return func(w http.ResponseWriter, r *http.Request) {
		render(w, "about", d)
	}
}