// page.go — what a template gets, and how links are formed.
//
// The same templates render two ways: as a static export (relative links,
// ".html" suffixes, no server-side features) and as the live web app
// (absolute routes, htmx-driven filters, comments and jj queries). Pages carry
// Live so a template can ask for the difference in one place.
package web

import (
	"html/template"
	"net/url"
	"strconv"
	"strings"
)

type page struct {
	Site     *Site
	Title    string
	Kind     string // index | file | files | notes | note | jj | change | session
	Root     string // static: relative prefix; live: route prefix ending in "/"
	Live     bool
	Rev      string // revision being browsed ("" = the change the log points at)
	ChangeID string // resolved change id for Rev — what pages name and link
	Commit   string // the commit under it — what content is read and cached at
	Default  string // the change the log points at
	Path     string // this request's path, so the change bar can re-aim it
	Current  string // current file path, for the tree
	User     string // who web comments are attributed to

	// what this view is scoped to. Scope is "change" (only what was recorded
	// at ChangeID) or "all"; ScopeEmpty means "change" was asked for but
	// nothing was ever recorded there, so the whole log is showing instead.
	Scope      string
	ScopeEmpty bool
	Here       int // notes recorded at this change
	Elsewhere  int // notes recorded at any other change
	ChangeInfo *Row

	Tree  template.HTML
	File  *File
	Files []*File // every file at this change, for counts

	// one note on its own page — the permalink. Excerpt is the code it is
	// about, already rendered; ExErr says why there is none.
	Note         *Note
	Thread       *ThreadNode
	Excerpt      template.HTML
	ExFrom, ExTo int
	ExErr        string

	Notes    []*Note
	Filter   NoteFilter
	Facets   *Facets
	Sessions []*Session
	Compact  bool
	Window   string

	JJ     *JJView
	Change *Change
	Conv   *Conv
	Err    string
}

// JJView is one rendered jj query: what was asked, and what came back.
type JJView struct {
	Root   string
	Kind   string // log | op
	Revset string
	AtOp   string
	Limit  int
	Rows   []Row
	Err    string
}

// params carries the two things every link must not lose: which change you
// are looking at, and how wide the view is.
func (p *page) params() string { return p.paramsWith(p.Scope) }

func (p *page) paramsWith(scope string) string {
	var q []string
	// "@" is a revset like any other now that the default change is the log's,
	// so dropping it here would slide the reader off the change they picked
	if p.Rev != "" {
		q = append(q, "rev="+url.QueryEscape(p.Rev))
	}
	if scope == "all" {
		q = append(q, "scope=all")
	}
	if len(q) == 0 {
		return ""
	}
	return "?" + strings.Join(q, "&")
}

// ScopeHref is this same page seen with the other scope.
func (p *page) ScopeHref(scope string) string {
	path := p.Path
	if path == "" {
		path = p.liveRoot()
	}
	return path + p.paramsWith(scope)
}

// BackHref is this page again at the change the log points at.
func (p *page) BackHref() string {
	q := ""
	if p.Scope == "all" {
		q = "?scope=all"
	}
	return p.JumpPath() + q
}

// JumpPath is where the change picker submits: your own page when it is one
// that can be read at any change, the file tree otherwise.
func (p *page) JumpPath() string {
	switch p.Kind {
	case "index", "file", "files", "notes", "note":
		if p.Path != "" {
			return p.Path
		}
	}
	return p.liveRoot() + "files"
}

func (p *page) liveRoot() string {
	root := p.Root
	if root == "" {
		return "/"
	}
	if !strings.HasPrefix(root, "/") {
		root = "/" + root
	}
	if !strings.HasSuffix(root, "/") {
		root += "/"
	}
	return root
}

// Href maps a logical destination to a URL for this page's mode. Kinds the
// static export has no page for return "", and templates guard on .Live.
func (p *page) Href(kind string, arg ...string) string {
	a := ""
	if len(arg) > 0 {
		a = arg[0]
	}
	if p.Live {
		root := p.liveRoot()
		switch kind {
		case "":
			return root + p.params()
		case "notes":
			return root + "notes" + p.params()
		case "notes-list":
			return root + "notes/list" + p.params()
		case "files":
			return root + "files" + p.params()
		case "tree":
			return root + "tree" + p.params()
		case "jj":
			return root + "jj"
		case "jj-log":
			return root + "jj/log"
		case "jj-op":
			return root + "jj/op"
		case "activity":
			return root + "activity"
		case "code":
			return root + "code/" + escPath(a) + p.params()
		case "note":
			return root + "note/" + a
		case "change":
			return root + "change/" + a
		case "session":
			return root + "session/" + escPath(a)
		case "asset":
			return root + a
		}
		return root
	}
	switch kind {
	case "":
		return p.Root + "index.html"
	case "notes":
		return p.Root + "notes.html"
	case "files":
		return p.Root + "files.html"
	case "tree":
		return p.Root + "tree.html"
	case "code":
		return p.Root + "code/" + a + ".html"
	case "note":
		return p.Root + "note/" + a + ".html"
	case "asset":
		return p.Root + a
	}
	return ""
}

// codeLink is the tree's per-file linker for this page's mode.
func (p *page) codeLink() func(string) string {
	return func(path string) string { return p.Href("code", path) }
}

func escPath(p string) string {
	parts := strings.Split(p, "/")
	for i, s := range parts {
		parts[i] = url.PathEscape(s)
	}
	return strings.Join(parts, "/")
}

// ConvHref opens the conversation a note was written in, anchored on it. It
// needs the transcripts on this machine, so the static export has none — and
// the conversation itself does not link back to where you already are.
func (p *page) ConvHref(n *Note) string {
	if !p.Live || p.Kind == "session" || n.Session == "" || safeSession(n.Session) != nil {
		return ""
	}
	id := strconv.Itoa(n.ID)
	return p.Href("session", n.Session) + "?note=" + id + "#note-" + id
}

// PermaHref is the note's own page: the link to hand someone else. It is the
// one link on the card that names nothing but the note, so it survives the
// change scope, the filters, and the file having moved on since.
//
// It is empty on the note's own page, which is where it already points, and in
// a static export of a different change, which has no page for it.
func (p *page) PermaHref(n *Note) string {
	if p.Kind == "note" && (p.Note == nil || p.Note.ID == n.ID) {
		return ""
	}
	if !p.Live && p.Site != nil && p.Site.NoteByID(n.ID) == nil {
		return ""
	}
	return p.Href("note", strconv.Itoa(n.ID))
}

// ThreadHref opens the incoming replies and mentions for a note. The focused
// root only needs an in-page jump; every other card gets its own permalink.
func (p *page) ThreadHref(n *Note) string {
	if len(n.Replies) == 0 && len(n.Mentions) == 0 {
		return ""
	}
	if p.Kind == "note" && p.Note != nil && p.Note.ID == n.ID {
		return "#discussion"
	}
	h := p.Href("note", strconv.Itoa(n.ID))
	if h == "" {
		return ""
	}
	return h + "#discussion"
}

// ReplyHref is the explicit parent link. A static export may not contain the
// parent's change, in which case it leaves the relationship as text instead of
// manufacturing a link to a page the export did not write.
func (p *page) ReplyHref(n *Note) string {
	if n.ReplyTo < 1 {
		return ""
	}
	if !p.Live && p.Site != nil && p.Site.NoteByID(n.ReplyTo) == nil {
		return ""
	}
	return p.Href("note", strconv.Itoa(n.ReplyTo))
}

// HasCode reports whether this view has a page for a path. The live app can
// render any file at the change it is reading; a static export only wrote the
// ones present at the change it holds, so a note about a file that is not
// there must not offer a link into nothing.
func (p *page) HasCode(path string) bool {
	if p.Live {
		return path != ""
	}
	for _, f := range p.Files {
		if f.Path == path {
			return true
		}
	}
	return false
}

// NoteHref points at the noted line, or the note list when it is unpinned.
// The ?note= is what turns a jump into an arrival: the page opens in notes
// focus with the card flashed and its lines marked (see app.js).
func (p *page) NoteHref(n *Note) string {
	if n.File == "" {
		return p.Href("notes")
	}
	id := strconv.Itoa(n.ID)
	h := p.Href("code", n.File)
	sep := "?"
	if strings.Contains(h, "?") {
		sep = "&"
	}
	h += sep + "note=" + id
	if n.Start > 0 {
		h += "#L" + strconv.Itoa(n.Start)
	}
	return h
}

// newTemplates parses the page templates. The highlighter comes along because
// note bodies are markdown, and a fenced code block in a note is painted by
// the same grammars as the code view.
func newTemplates(hl *highlighter) *template.Template {
	md := newMarkdown(hl)
	funcs := template.FuncMap{
		"short": short,
		"md":    md.renderAt,
		"band":  func(a, b uint8) bool { return b != 0 && a&b != 0 },
		"lines": func(n *Note) string {
			if n.Start <= 0 {
				return "whole file"
			}
			if n.End > n.Start {
				return ":" + strconv.Itoa(n.Start) + "-" + strconv.Itoa(n.End)
			}
			return ":" + strconv.Itoa(n.Start)
		},
		"base": func(p string) string {
			if i := strings.LastIndex(p, "/"); i >= 0 {
				return p[i+1:]
			}
			return p
		},
		"dict": func(kv ...any) map[string]any {
			m := map[string]any{}
			for i := 0; i+1 < len(kv); i += 2 {
				m[kv[i].(string)] = kv[i+1]
			}
			return m
		},
	}
	tpl, err := template.New("layout.tmpl").Funcs(funcs).ParseFS(tfs, "templates/*.tmpl")
	if err != nil {
		fatal("%v", err)
	}
	return tpl
}

func short(s string) string {
	if len(s) > 8 {
		return s[:8]
	}
	return s
}