package main

import (
	"bytes"
	"fmt"
	"html"
	"log"
	"net/http"
	"net/url"
	"strings"

	"github.com/yuin/goldmark"
)

func (this *Application) Repopage(w http.ResponseWriter, r *http.Request, repoName string) {
	ctx := r.Context()
	repoURL := this.cfg.Gitea.URL + url.PathEscape(this.cfg.Gitea.Org) + `/` + url.PathEscape(repoName)
	extraHead := ""

	readme, err := this.gitea.RepoFile(ctx, repoName, `README.md`)
	if err != nil {
		log.Printf("%s %s: %s", r.Method, r.URL.Path, err)
		http.Redirect(w, r, repoURL, http.StatusTemporaryRedirect)
		return
	}

	lines := strings.Split(string(readme), "\n")

	// Check if this repo has the 'article' tag
	hasArticleTag := false
	this.reposMut.RLock()
	for _, rr := range this.reposCache {
		if rr.Name != repoName {
			continue
		}
		for _, topic := range rr.Topics {
			if topic == "article" {
				hasArticleTag = true
				break
			}
		}
	}
	this.reposMut.RUnlock()

	// We add some extra badges based on special text entries
	extraBadgesMd := ``
	if !hasArticleTag {
		extraBadgesMd += ` %%REPLACEME__BADGE%%`
	}
	extraBadgesMd += ` [![](https://img.shields.io/badge/vcs-git-green?logo=git)](` + repoURL + `)`

	// Inject more badges to 3rd line; or, create badges on 3rd line if there are none already
	if len(lines) >= 3 && strings.Contains(lines[2], `shields.io`) {
		lines[2] += ` ` + extraBadgesMd
	} else {
		// Push other lines down
		lines = append([]string{lines[0], lines[1], extraBadgesMd, ""}, lines[2:]...)
	}

	readmeHtml, err := this.gitea.RenderMarkdown(ctx, repoName, strings.Join(lines, "\n"))
	if err != nil {
		log.Printf("%s %s: %s", r.Method, r.URL.Path, fmt.Errorf("rendering markdown: %w", err))

		// Failed to use Gitea's markdown renderer
		// HTTP 401 (Unauthorized) started happening with this API sometime
		// between Gitea 1.18 -> 1.21, and no authorization token seems
		// sufficient to make it work again
		// Use our own one instead as a fallback
		buff := bytes.Buffer{}
		err = goldmark.Convert(readme, &buff)

		if err != nil {
			// Built-in markdown renderer didn't work either
			log.Printf("%s %s: %s", r.Method, r.URL.Path, fmt.Errorf("rendering markdown: %w", err))
			http.Redirect(w, r, repoURL, http.StatusTemporaryRedirect)
			return
		}

		// OK
		readmeHtml = buff.Bytes()
		err = nil
	}

	readmeHtml = []byte(strings.Replace(string(readmeHtml), `%%REPLACEME__BADGE%%`, `<img src="/static/build_success_brightgreen.svg" style="width:90px;height:20px;">`, 1))

	images, err := this.gitea.ImageFilesForRepo(ctx, repoName)
	if err != nil {
		log.Printf("%s %s: %s", r.Method, r.URL.Path, fmt.Errorf("listing images: %w", err))
		http.Redirect(w, r, repoURL, http.StatusTemporaryRedirect)
		return
	}

	// If the Git repository contains a top-level go.mod file, allow vanity imports
	if goMod, err := this.gitea.RepoFile(ctx, repoName, `go.mod`); err == nil {

		// Check the first line should be `module MODULENAME\n`
		firstLine := bytes.SplitN(goMod, []byte("\n"), 2)[0]
		if bytes.HasPrefix(firstLine, []byte("module ")) {
			moduleName := firstLine[7:]
			extraHead = `<meta name="go-import" content="` + html.EscapeString(string(moduleName)) + ` git ` + repoURL + `.git">`
		}
	}

	// De-escalate all headers in rendered markdown to match our style
	repl := strings.NewReplacer(`<h1`, `<h2`, `<h2`, `<h3`, `<h3`, `<h4`,
		`</h1>`, `</h2>`, `</h2>`, `</h3>`, `</h3>`, `</h4>`)

	// Ready for template

	this.Templatepage(w, r, repoName, extraHead, func() {

		projBodyclass := `projbody`
		if len(images) > 0 {
			projBodyclass += ` projbody_halfw`
		}

		fmt.Fprint(w, `<div class="projinfo"><div class="`+projBodyclass+`">`)
		repl.WriteString(w, string(readmeHtml))
		fmt.Fprint(w, `</div>`)

		if len(images) > 0 {
			fmt.Fprint(w, `<div class="projimg">`)
			for _, img := range images {
				fmt.Fprint(w, `<a href="`+html.EscapeString(img.RawURL)+`"><img alt="" class="thumbimage" src="`+html.EscapeString(img.RawURL)+`" /></a>`)
			}
			fmt.Fprint(w, `</div>`)
		}

		fmt.Fprint(w, `<div style="clear:both;"></div>`)
		fmt.Fprint(w, `</div>`) // projbody
	})
}