// static.go — the offline export: the same pages written out as files.
//
// Everything that needs a server (comments, live activity, jj queries) is
// omitted; the trace/notes toggle, the file finder and the note filters all
// keep working, since they run in the browser.
package web

import (
	"bytes"
	"fmt"
	"html/template"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"strconv"
	"strings"
	"sync"
	"time"
)

func run(dir string, name string, args ...string) []byte {
	cmd := exec.Command(name, args...)
	cmd.Dir = dir
	out, err := cmd.Output()
	if err != nil {
		if ee, ok := err.(*exec.ExitError); ok {
			os.Stderr.Write(ee.Stderr)
		}
		fatal("%s %s: %v", name, strings.Join(args, " "), err)
	}
	return out
}

func buildSite(log logStore, repoAbs, out, title string, theme, light *Theme, themes *themeSet) {
	start := time.Now()
	entries := readLog(log)
	ranked := buildModel(title, entries, "").Ranked
	if len(ranked) == 0 {
		fatal("log has no jj change ids")
	}
	// the most-logged change this repo actually has: a log can span repos, and
	// the busiest change in it may belong to another one
	var change string
	var list []byte
	for _, c := range ranked {
		out, err := jjRun(repoAbs, "file", "list", "-r", c)
		if err == nil {
			change, list = c, out
			break
		}
	}
	if change == "" {
		fatal("none of the log's %d changes are in %s — logs are per repository; point -repo at the one the trace was recorded in",
			len(ranked), repoAbs)
	}
	// an export is a picture of one change, so it holds only what was
	// recorded there; the notes page says how much of the log that leaves out
	site := buildModel(title, entries, change)
	site.Change = change
	site.Theme, site.Light, site.Repo = theme, light, repoAbs
	site.All = site.filesAt(strings.Split(strings.TrimRight(string(list), "\n"), "\n"), change)

	commit := strings.TrimSpace(string(mustJJ(repoAbs, "log", "-r", site.Change, "--no-graph", "-T", "commit_id")))
	tmp, err := os.MkdirTemp("", "notevi-")
	if err != nil {
		fatal("%v", err)
	}
	defer os.RemoveAll(tmp)
	archive := exec.Command("git", "-C", repoAbs, "archive", commit)
	untar := exec.Command("tar", "-x", "-C", tmp)
	untar.Stdin, _ = archive.StdoutPipe()
	untar.Stderr = os.Stderr
	if err := untar.Start(); err != nil {
		fatal("tar: %v", err)
	}
	if err := archive.Run(); err != nil {
		fatal("git archive %s: %v", short(commit), err)
	}
	if err := untar.Wait(); err != nil {
		fatal("tar: %v", err)
	}

	writeSite(site, out, tmp, themes)
	stubs := 0
	for _, f := range site.All {
		if f.Stub != "" {
			stubs++
		}
	}
	fmt.Printf("notevi web: %d files (%d traced, %d not rendered), %d notes, %d agents in %s -> %s\n",
		len(site.All), len(site.Order), stubs, len(site.Notes), len(site.Agents),
		time.Since(start).Round(time.Millisecond), out)
}

func writeSite(site *Site, out, srcDir string, themes *themeSet) {
	if themes == nil {
		themes = &themeSet{}
	}
	hl := newHighlighter(site.Theme, site.Light)
	tpl := newTemplates(hl)
	if err := os.MkdirAll(out, 0o755); err != nil {
		fatal("%v", err)
	}

	each := func(fn func(f *File)) {
		sem := make(chan struct{}, runtime.NumCPU())
		var wg sync.WaitGroup
		for _, f := range site.All {
			wg.Add(1)
			sem <- struct{}{}
			go func(f *File) {
				defer func() { <-sem; wg.Done() }()
				fn(f)
			}(f)
		}
		wg.Wait()
	}
	// phase A: content — coverage percentages must exist before any tree
	// or index below is written
	each(func(f *File) {
		src, err := os.ReadFile(filepath.Join(srcDir, f.Path))
		switch {
		case err != nil:
			f.Stub = "not present in the archived commit"
		case bytes.IndexByte(src, 0) >= 0:
			f.Stub = "binary file — not rendered"
		case len(src) > 2<<20:
			f.Stub = fmt.Sprintf("file too large to render (%d KB)", len(src)/1024)
		default:
			f.render(src, hl)
		}
	})

	cf := mustCreate(filepath.Join(out, "style.css"))
	if err := renderCSS(cf, site); err != nil {
		fatal("css: %v", err)
	}
	cf.Close()
	for _, name := range []string{"app.js", "bemtevi.svg"} {
		b, err := tfs.ReadFile("assets/" + name)
		if err != nil {
			fatal("%v", err)
		}
		if err := os.WriteFile(filepath.Join(out, name), b, 0o644); err != nil {
			fatal("%v", err)
		}
	}
	// the picker travels with the export: a <script src>/<link> pair loads
	// from the filesystem, which is why the menu is a script and not JSON
	for name, b := range map[string][]byte{"themes.css": themes.CSS, "themes.js": themes.JS} {
		if err := os.WriteFile(filepath.Join(out, name), b, 0o644); err != nil {
			fatal("%v", err)
		}
	}

	// shared tree fragment: the only nav tree, fetched by every page; "@@" is
	// replaced with the page root by app.js, since the fragment is fetched
	// from any page depth
	treeFrag := renderTree(site.All, func(p string) string { return "@@code/" + p + ".html" })
	if err := os.WriteFile(filepath.Join(out, "tree.html"), []byte(treeFrag), 0o644); err != nil {
		fatal("%v", err)
	}

	facets := site.Facets()
	var info *Row
	if rows, err := LogRows(site.Repo, site.Change, "", 1); err == nil {
		for _, row := range rows {
			if !row.Blank() {
				r := row
				info = &r
				break
			}
		}
	}
	render := func(path string, p *page) {
		p.Site, p.Facets = site, facets
		p.ChangeID, p.Default, p.ChangeInfo = site.Change, site.Change, info
		p.Scope, p.Here = "change", site.NotesAt[site.Change]
		p.Elsewhere = site.NotesTotal - p.Here
		p.Files = site.All
		f := mustCreate(path)
		if err := tpl.Execute(f, p); err != nil {
			fatal("render %s: %v", path, err)
		}
		f.Close()
	}

	latest := site.FilterNotes(NoteFilter{})
	if len(latest) > 24 {
		latest = latest[:24]
	}
	render(filepath.Join(out, "index.html"), &page{Kind: "index", Title: site.Title, Notes: latest})

	fullTree := renderTree(site.All, func(p string) string { return "code/" + p + ".html" })
	render(filepath.Join(out, "files.html"), &page{Kind: "files", Title: "files — " + site.Title,
		Tree: template.HTML(fullTree)})

	render(filepath.Join(out, "notes.html"), &page{Kind: "notes", Title: "notes — " + site.Title,
		Notes: site.FilterNotes(NoteFilter{})})

	// phase B: every file page, in parallel
	each(func(f *File) {
		dst := filepath.Join(out, "code", f.Path+".html")
		os.MkdirAll(filepath.Dir(dst), 0o755)
		depth := strings.Count(f.Path, "/") + 1
		render(dst, &page{Kind: "file", Title: f.Path + " — " + site.Title,
			Root: strings.Repeat("../", depth), Current: f.Path, File: f})
	})

	// phase C: a page per note, so a permalink handed to someone else opens
	// in the export exactly as it does in the live app. The source is read
	// again rather than kept from phase A: an export is a batch job, and the
	// alternative is holding every file in memory for the sake of a few
	// hundred excerpts.
	if err := os.MkdirAll(filepath.Join(out, "note"), 0o755); err != nil {
		fatal("%v", err)
	}
	for _, n := range site.Notes {
		p := &page{Kind: "note", Title: noteTitle(n) + " — " + site.Title,
			Root: "../", Current: n.File, Note: n, Thread: site.NoteThread(n.ID)}
		if n.File != "" && n.Start > 0 {
			src, err := os.ReadFile(filepath.Join(srcDir, n.File))
			switch {
			case err != nil:
				p.ExErr = "not present in the archived commit"
			case bytes.IndexByte(src, 0) >= 0:
				p.ExErr = "binary file — not rendered"
			default:
				var cov []uint8
				if f, ok := site.Files[n.File]; ok {
					cov = f.Cov
				}
				p.Excerpt, p.ExFrom, p.ExTo = excerptFor(n.File, src, cov, hl, n)
			}
		}
		render(filepath.Join(out, "note", strconv.Itoa(n.ID)+".html"), p)
	}
}

func mustCreate(path string) *os.File {
	f, err := os.Create(path)
	if err != nil {
		fatal("%v", err)
	}
	return f
}