#!/usr/bin/env lua
--
-- lume-docs-build.lua
-- Converts Lume's Markdown documentation into a standalone HTML site.
-- Usage: lua lume-docs-build.lua [input.md] [output.html]
--        Defaults: DOCS.md -> docs/index.html
--

local infile  = arg and arg[1] or "DOCS.md"
local outfile = arg and arg[2] or "index.html"

-- ── Utilities ────────────────────────────────────────────────────────────────

local function read_file(path)
  local f, err = io.open(path, "r")
  if not f then
    io.stderr:write("lume-docs-build: cannot open '" .. path .. "': " .. tostring(err) .. "\n")
    os.exit(1)
  end
  local content = f:read("*a")
  f:close()
  return content
end

local function write_file(path, content)
  -- create parent directory if it doesn't exist (best-effort)
  local dir = path:match("^(.*)/[^/]+$")
  if dir and dir ~= "" then os.execute("mkdir -p " .. dir) end
  local f, err = io.open(path, "w")
  if not f then
    io.stderr:write("lume-docs-build: cannot write '" .. path .. "': " .. tostring(err) .. "\n")
    os.exit(1)
  end
  f:write(content)
  f:close()
end

local function escape_html(s)
  return (s:gsub("&", "&")
            :gsub("<", "&lt;")
            :gsub(">", "&gt;")
            :gsub('"', "&quot;"))
end

-- ── Slug generation (for heading anchors) ────────────────────────────────────

local function slugify(text)
  -- strip markdown inline code and links from heading text
  text = text:gsub("`[^`]+`", function(m) return m:sub(2,-2) end)
  text = text:gsub("%[(.-)%]%(.-%)","  %1")
  text = text:lower()
  text = text:gsub("[^%a%d%s%-]", "")
  text = text:gsub("%s+", "-")
  text = text:gsub("^%-+", ""):gsub("%-+$", "")
  return text
end

-- ── Inline Markdown → HTML ────────────────────────────────────────────────────
-- Handles: **bold**, *italic*, `code`, [text](url), and bare anchors

local function inline_md(s)
  -- escape HTML first so we don't double-escape our own tags
  s = escape_html(s)

  -- code spans (backtick) — protect from further processing
  local code_stash = {}
  s = s:gsub("`([^`]+)`", function(c)
    code_stash[#code_stash+1] = '<code class="inline-code">' .. c .. "</code>"
    return "\x00CODE" .. #code_stash .. "\x00"
  end)

  -- bold + italic  ***text***
  s = s:gsub("%*%*%*(.-)%*%*%*", "<strong><em>%1</em></strong>")
  -- bold  **text**
  s = s:gsub("%*%*(.-)%*%*", "<strong>%1</strong>")
  -- italic  *text*
  s = s:gsub("%*(.-)%*", "<em>%1</em>")

  -- links  [text](url)
  s = s:gsub("%[(.-)%]%((.-)%)", function(txt, url)
    -- internal anchor links start with #
    if url:sub(1,1) == "#" then
      return '<a href="' .. url .. '">' .. txt .. "</a>"
    end
    return '<a href="' .. url .. '" target="_blank" rel="noopener">' .. txt .. "</a>"
  end)

  -- restore code spans
  s = s:gsub("\x00CODE(%d+)\x00", function(n)
    return code_stash[tonumber(n)]
  end)

  return s
end

-- ── Syntax highlighting for code blocks ──────────────────────────────────────
-- Simple but good-enough token colouring for lua, c, sh, and text.

local SH_KEYWORDS = {
  ["if"]=1,["then"]=1,["else"]=1,["elif"]=1,["fi"]=1,
  ["for"]=1,["while"]=1,["do"]=1,["done"]=1,["case"]=1,
  ["esac"]=1,["in"]=1,["function"]=1,["return"]=1,
  ["local"]=1,["export"]=1,["echo"]=1,["exit"]=1,
}

local LUA_KEYWORDS = {
  ["and"]=1,["break"]=1,["do"]=1,["else"]=1,["elseif"]=1,
  ["end"]=1,["false"]=1,["for"]=1,["function"]=1,["goto"]=1,
  ["if"]=1,["in"]=1,["local"]=1,["nil"]=1,["not"]=1,
  ["or"]=1,["repeat"]=1,["return"]=1,["then"]=1,["true"]=1,
  ["until"]=1,["while"]=1,
}

local C_KEYWORDS = {
  ["auto"]=1,["break"]=1,["case"]=1,["char"]=1,["const"]=1,
  ["continue"]=1,["default"]=1,["do"]=1,["double"]=1,["else"]=1,
  ["enum"]=1,["extern"]=1,["float"]=1,["for"]=1,["goto"]=1,
  ["if"]=1,["inline"]=1,["int"]=1,["long"]=1,["register"]=1,
  ["return"]=1,["short"]=1,["signed"]=1,["sizeof"]=1,["static"]=1,
  ["struct"]=1,["switch"]=1,["typedef"]=1,["union"]=1,["unsigned"]=1,
  ["void"]=1,["volatile"]=1,["while"]=1,["NULL"]=1,["true"]=1,["false"]=1,
}

local function hl_lua(code)
  local out = {}
  local i, n = 1, #code
  while i <= n do
    local ch = code:sub(i,i)
    -- single-line comment
    if code:sub(i,i+1) == "--" then
      local rest = escape_html(code:sub(i))
      out[#out+1] = '<span class="hl-comment">' .. rest .. "</span>"
      break
    -- long string / comment stubs not handled — treated as unknown
    elseif ch == '"' or ch == "'" then
      local q, j = ch, i+1
      while j <= n do
        local c = code:sub(j,j)
        if c == "\\" then j=j+2 elseif c==q then j=j+1; break else j=j+1 end
      end
      out[#out+1] = '<span class="hl-string">'..escape_html(code:sub(i,j-1)).."</span>"
      i=j
    elseif ch:match("%d") then
      local j=i
      while j<=n and code:sub(j,j):match("[%d%.xXa-fA-F]") do j=j+1 end
      out[#out+1]='<span class="hl-number">'..escape_html(code:sub(i,j-1)).."</span>"
      i=j
    elseif ch:match("[%a_]") then
      local j=i
      while j<=n and code:sub(j,j):match("[%w_]") do j=j+1 end
      local word=code:sub(i,j-1)
      if LUA_KEYWORDS[word] then
        out[#out+1]='<span class="hl-keyword">'..word.."</span>"
      else
        out[#out+1]=escape_html(word)
      end
      i=j
    else
      out[#out+1]=escape_html(ch); i=i+1
    end
  end
  return table.concat(out)
end

local function hl_c(code)
  local out = {}
  local i, n = 1, #code
  while i <= n do
    local ch = code:sub(i,i)
    if code:sub(i,i+1) == "//" then
      out[#out+1]='<span class="hl-comment">'..escape_html(code:sub(i)).."</span>"; break
    elseif ch == '"' or ch == "'" then
      local q,j=ch,i+1
      while j<=n do
        local c=code:sub(j,j)
        if c=="\\" then j=j+2 elseif c==q then j=j+1;break else j=j+1 end
      end
      out[#out+1]='<span class="hl-string">'..escape_html(code:sub(i,j-1)).."</span>"; i=j
    elseif ch:match("%d") then
      local j=i
      while j<=n and code:sub(j,j):match("[%d%.xXuUlL]") do j=j+1 end
      out[#out+1]='<span class="hl-number">'..escape_html(code:sub(i,j-1)).."</span>"; i=j
    elseif ch:match("[%a_]") then
      local j=i
      while j<=n and code:sub(j,j):match("[%w_]") do j=j+1 end
      local word=code:sub(i,j-1)
      if C_KEYWORDS[word] then
        out[#out+1]='<span class="hl-keyword">'..word.."</span>"
      else
        out[#out+1]=escape_html(word)
      end
      i=j
    else
      out[#out+1]=escape_html(ch); i=i+1
    end
  end
  return table.concat(out)
end

local function hl_sh(code)
  local out = {}
  local i,n=1,#code
  while i<=n do
    local ch=code:sub(i,i)
    if ch=="#" then
      out[#out+1]='<span class="hl-comment">'..escape_html(code:sub(i)).."</span>"; break
    elseif ch=='"' or ch=="'" then
      local q,j=ch,i+1
      while j<=n do
        local c=code:sub(j,j)
        if ch=='"' and c=="\\" then j=j+2 elseif c==q then j=j+1;break else j=j+1 end
      end
      out[#out+1]='<span class="hl-string">'..escape_html(code:sub(i,j-1)).."</span>"; i=j
    elseif ch=="$" then
      out[#out+1]='<span class="hl-operator">$</span>'; i=i+1
    elseif ch:match("[%a_]") then
      local j=i
      while j<=n and code:sub(j,j):match("[%w_]") do j=j+1 end
      local word=code:sub(i,j-1)
      if SH_KEYWORDS[word] then
        out[#out+1]='<span class="hl-keyword">'..word.."</span>"
      else
        out[#out+1]=escape_html(word)
      end
      i=j
    else
      out[#out+1]=escape_html(ch); i=i+1
    end
  end
  return table.concat(out)
end

local highlighters = { lua=hl_lua, c=hl_c, sh=hl_sh, bash=hl_sh, zsh=hl_sh }

local function highlight_code(lang, code)
  local hl = lang and highlighters[lang:lower()]
  if hl then
    -- highlight line by line
    local lines = {}
    for line in (code .. "\n"):gmatch("([^\n]*)\n") do
      lines[#lines+1] = hl(line)
    end
    return table.concat(lines, "\n")
  end
  return escape_html(code)
end

-- ── Block-level Markdown parser ───────────────────────────────────────────────

local function parse_md(src)
  local lines = {}
  for ln in (src .. "\n"):gmatch("([^\n]*)\n") do
    lines[#lines+1] = ln
  end

  local out         = {}
  local toc         = {}   -- {level, text, slug}
  local i           = 1
  local in_list     = false
  local in_para     = false

  local function close_para()
    if in_para then out[#out+1] = "</p>"; in_para = false end
  end
  local function close_list()
    if in_list then out[#out+1] = "</ul>"; in_list = false end
  end
  local function close_all() close_list(); close_para() end

  -- track duplicate slugs
  local slug_count = {}
  local function unique_slug(text)
    local base = slugify(text)
    slug_count[base] = (slug_count[base] or 0) + 1
    if slug_count[base] == 1 then return base end
    return base .. "-" .. slug_count[base]
  end

  while i <= #lines do
    local line = lines[i]

    -- fenced code block  ```lang
    local fence_lang = line:match("^```(%w*)")
    if fence_lang ~= nil then
      close_all()
      local lang = fence_lang ~= "" and fence_lang or nil
      local code_lines = {}
      i = i + 1
      while i <= #lines and not lines[i]:match("^```%s*$") do
        code_lines[#code_lines+1] = lines[i]
        i = i + 1
      end
      local raw  = table.concat(code_lines, "\n")
      local body = highlight_code(lang, raw)
      local lang_label = lang and ('<span class="code-lang">' .. escape_html(lang) .. "</span>") or ""
      out[#out+1] = '<div class="code-block">'
                 .. lang_label
                 .. '<button class="copy-btn" onclick="copyCode(this)" title="Copy">⎘</button>'
                 .. '<pre><code>'
                 .. body
                 .. "</code></pre></div>"
      i = i + 1
      goto continue
    end

    -- heading  # ## ### ####
    local hlevel, htext = line:match("^(#+)%s+(.*)")
    if hlevel then
      close_all()
      local lvl = math.min(#hlevel, 4)
      local slug = unique_slug(htext)
      toc[#toc+1] = {level=lvl, text=htext, slug=slug}
      -- add data-level for sidebar indentation
      out[#out+1] = string.format(
        '<h%d id="%s" class="doc-heading" data-level="%d">'
        .. '<a class="heading-anchor" href="#%s">¶</a>%s</h%d>',
        lvl, slug, lvl, slug, inline_md(htext), lvl)
      i = i + 1
      goto continue
    end

    -- horizontal rule  ---
    if line:match("^%-%-%-+%s*$") or line:match("^%*%*%*+%s*$") then
      close_all()
      out[#out+1] = "<hr>"
      i = i + 1
      goto continue
    end

    -- blockquote  > text
    if line:match("^>") then
      close_all()
      local bq_lines = {}
      while i <= #lines and lines[i]:match("^>") do
        bq_lines[#bq_lines+1] = lines[i]:match("^>%s?(.*)")
        i = i + 1
      end
      out[#out+1] = "<blockquote><p>" .. inline_md(table.concat(bq_lines, " ")) .. "</p></blockquote>"
      goto continue
    end

    -- table  | col | col |
    if line:match("^|") then
      close_all()
      local tbl_lines = {}
      while i <= #lines and lines[i]:match("^|") do
        tbl_lines[#tbl_lines+1] = lines[i]
        i = i + 1
      end
      out[#out+1] = '<div class="table-wrap"><table>'
      local header_done = false
      for _, tl in ipairs(tbl_lines) do
        -- separator row  |---|---|
        if tl:match("^|[-| :]+|%s*$") then
          header_done = true
        else
          local cells = {}
          for cell in (tl .. "|"):gmatch("|([^|]*)|?") do
            -- skip trailing empty captures
            cells[#cells+1] = cell
          end
          -- remove last empty cell from the trailing | pattern
          if cells[#cells] and cells[#cells]:match("^%s*$") then
            table.remove(cells)
          end
          if not header_done then
            out[#out+1] = "<thead><tr>"
            for _, cell in ipairs(cells) do
              out[#out+1] = "<th>" .. inline_md(cell:match("^%s*(.-)%s*$")) .. "</th>"
            end
            out[#out+1] = "</tr></thead><tbody>"
          else
            out[#out+1] = "<tr>"
            for _, cell in ipairs(cells) do
              out[#out+1] = "<td>" .. inline_md(cell:match("^%s*(.-)%s*$")) .. "</td>"
            end
            out[#out+1] = "</tr>"
          end
        end
      end
      out[#out+1] = "</tbody></table></div>"
      goto continue
    end

    -- unordered list  - item or * item
    if line:match("^%s*[%-%*]%s+") then
      close_para()
      if not in_list then out[#out+1] = '<ul class="doc-list">'; in_list = true end
      local item = line:match("^%s*[%-%*]%s+(.*)")
      out[#out+1] = "<li>" .. inline_md(item) .. "</li>"
      i = i + 1
      goto continue
    end

    -- ordered list  1. item
    if line:match("^%s*%d+%.%s+") then
      close_para()
      if not in_list then out[#out+1] = '<ol class="doc-list">'; in_list = true end
      local item = line:match("^%s*%d+%.%s+(.*)")
      out[#out+1] = "<li>" .. inline_md(item) .. "</li>"
      i = i + 1
      goto continue
    end

    -- blank line
    if line:match("^%s*$") then
      close_all()
      i = i + 1
      goto continue
    end

    -- paragraph / continuation
    close_list()
    if not in_para then
      out[#out+1] = "<p>"
      in_para = true
    else
      out[#out+1] = " "
    end
    out[#out+1] = inline_md(line)
    i = i + 1

    ::continue::
  end

  close_all()
  return table.concat(out, "\n"), toc
end

-- ── TOC sidebar HTML ──────────────────────────────────────────────────────────

local function build_sidebar(toc)
  local out = {}
  out[#out+1] = '<nav id="sidebar" aria-label="Table of contents">'
  out[#out+1] = '<div id="sidebar-header">'
  out[#out+1] = '  <span class="sidebar-title">Lume</span>'
  out[#out+1] = '  <span class="sidebar-version">0.1 Alpha</span>'
  out[#out+1] = '</div>'
  out[#out+1] = '<div id="sidebar-search-wrap">'
  out[#out+1] = '  <input id="sidebar-search" type="text" placeholder="Filter…" aria-label="Filter sections">'
  out[#out+1] = '</div>'
  out[#out+1] = '<ul id="toc-list">'
  for _, entry in ipairs(toc) do
    -- skip h1 from TOC (document title)
    if entry.level >= 2 then
      local indent = (entry.level - 2) * 14
      local clean  = entry.text
                       :gsub("`([^`]+)`", "%1")
                       :gsub("%[(.-)%]%(.-%)","  %1")
      out[#out+1] = string.format(
        '<li class="toc-item toc-level-%d" style="padding-left:%dpx">'
        .. '<a href="#%s" class="toc-link">%s</a></li>',
        entry.level, indent, entry.slug, escape_html(clean))
    end
  end
  out[#out+1] = '</ul></nav>'
  return table.concat(out, "\n")
end

-- ── Full HTML template ────────────────────────────────────────────────────────

local function build_html(title, sidebar_html, body_html)
  return string.format([[<!DOCTYPE html>
<html lang="en" data-theme="dark">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>%s</title>
<style>
/* ── Reset ─────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

/* ── Tokens ─────────────────────────────────────────── */
:root {
  --font-body:   "Inter", "Segoe UI", system-ui, sans-serif;
  --font-mono:   "JetBrains Mono", "Fira Code", "Cascadia Code", ui-monospace, monospace;
  --font-size:   15px;
  --line-height: 1.7;
  --sidebar-w:   260px;
  --radius:      6px;
  --transition:  0.2s ease;
}
[data-theme="dark"] {
  --bg:          #0f1117;
  --bg-alt:      #181b24;
  --bg-code:     #12141c;
  --bg-sidebar:  #13161e;
  --border:      #2a2d3a;
  --text:        #c9d1e0;
  --text-muted:  #6b7280;
  --text-head:   #e8ecf4;
  --accent:      #7c91f5;
  --accent-dim:  #3d4a8a;
  --link:        #7c91f5;
  --link-hover:  #a5b4fc;
  --hl-keyword:  #7c91f5;
  --hl-string:   #86efac;
  --hl-comment:  #4b5563;
  --hl-number:   #fca5a5;
  --hl-operator: #fcd34d;
  --tag-bg:      #1e2130;
  --tag-text:    #94a3b8;
  --shadow:      0 4px 24px rgba(0,0,0,0.5);
}
[data-theme="light"] {
  --bg:          #f8f9fc;
  --bg-alt:      #ffffff;
  --bg-code:     #eef0f6;
  --bg-sidebar:  #f0f2f8;
  --border:      #d1d5e0;
  --text:        #1e2030;
  --text-muted:  #6b7280;
  --text-head:   #111827;
  --accent:      #4f5fe8;
  --accent-dim:  #c7ccf7;
  --link:        #4255d4;
  --link-hover:  #2d3fa8;
  --hl-keyword:  #4255d4;
  --hl-string:   #166534;
  --hl-comment:  #9ca3af;
  --hl-number:   #b91c1c;
  --hl-operator: #92400e;
  --tag-bg:      #e5e7f0;
  --tag-text:    #374151;
  --shadow:      0 4px 24px rgba(0,0,0,0.08);
}

/* ── Base ────────────────────────────────────────────── */
html { scroll-behavior: smooth; }
body {
  font-family: var(--font-body);
  font-size:   var(--font-size);
  line-height: var(--line-height);
  color:       var(--text);
  background:  var(--bg);
  display:     flex;
  min-height:  100vh;
}

/* ── Sidebar ─────────────────────────────────────────── */
#sidebar {
  width:      var(--sidebar-w);
  min-width:  var(--sidebar-w);
  background: var(--bg-sidebar);
  border-right: 1px solid var(--border);
  height:     100vh;
  position:   sticky;
  top:        0;
  display:    flex;
  flex-direction: column;
  overflow:   hidden;
  flex-shrink: 0;
  transition: width var(--transition);
}
#sidebar-header {
  display:     flex;
  align-items: baseline;
  gap:         8px;
  padding:     18px 16px 10px;
  border-bottom: 1px solid var(--border);
}
.sidebar-title   { font-weight: 700; font-size: 17px; color: var(--text-head); letter-spacing: 0.03em; }
.sidebar-version {
  font-size:  11px;
  background: var(--tag-bg);
  color:      var(--tag-text);
  border:     1px solid var(--border);
  padding:    1px 6px;
  border-radius: 99px;
  font-family: var(--font-mono);
}
#sidebar-search-wrap { padding: 8px 12px; }
#sidebar-search {
  width:       100%%;
  background:  var(--bg);
  border:      1px solid var(--border);
  border-radius: var(--radius);
  padding:     6px 10px;
  color:       var(--text);
  font-size:   13px;
  outline:     none;
  transition:  border-color var(--transition);
}
#sidebar-search:focus { border-color: var(--accent); }
#toc-list {
  list-style:  none;
  overflow-y:  auto;
  flex:        1;
  padding:     6px 0 24px;
}
.toc-item { display: block; }
.toc-link {
  display:     block;
  padding:     3px 16px;
  color:       var(--text-muted);
  text-decoration: none;
  font-size:   13px;
  white-space: nowrap;
  overflow:    hidden;
  text-overflow: ellipsis;
  border-left: 2px solid transparent;
  transition:  color var(--transition), border-color var(--transition), background var(--transition);
}
.toc-link:hover          { color: var(--text); background: var(--bg-alt); }
.toc-link.active         { color: var(--accent); border-left-color: var(--accent); background: var(--bg-alt); }
.toc-level-2 .toc-link  { font-weight: 600; color: var(--text); }
.toc-level-3 .toc-link  { font-size: 12.5px; }
.toc-level-4 .toc-link  { font-size: 12px; }

/* ── Main content ────────────────────────────────────── */
#content {
  flex:        1;
  min-width:   0;
  padding:     0 0 80px;
}
#topbar {
  position:   sticky;
  top:        0;
  z-index:    100;
  display:    flex;
  justify-content: flex-end;
  align-items: center;
  padding:    8px 32px;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  gap:        12px;
}
#theme-toggle {
  background: var(--bg-alt);
  border:     1px solid var(--border);
  border-radius: var(--radius);
  color:      var(--text);
  cursor:     pointer;
  padding:    5px 12px;
  font-size:  13px;
  transition: background var(--transition), color var(--transition);
}
#theme-toggle:hover { background: var(--border); }
#doc-body { max-width: 820px; margin: 0 auto; padding: 40px 40px 0; }

/* ── Typography ──────────────────────────────────────── */
.doc-heading {
  color:       var(--text-head);
  margin-top:  2.2em;
  margin-bottom: 0.5em;
  position:    relative;
  scroll-margin-top: 56px;
}
h1.doc-heading { font-size: 2em;   border-bottom: 1px solid var(--border); padding-bottom: 0.3em; margin-top: 0.2em; }
h2.doc-heading { font-size: 1.5em; border-bottom: 1px solid var(--border); padding-bottom: 0.25em; }
h3.doc-heading { font-size: 1.2em; }
h4.doc-heading { font-size: 1em;   color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.06em; font-size: 0.82em; margin-top: 2.5em; }
.heading-anchor {
  opacity:     0;
  margin-left: 8px;
  font-size:   0.75em;
  color:       var(--text-muted);
  text-decoration: none;
  transition:  opacity var(--transition);
  user-select: none;
}
.doc-heading:hover .heading-anchor { opacity: 1; }
p  { margin-bottom: 1em; }
hr { border: none; border-top: 1px solid var(--border); margin: 2em 0; }
blockquote {
  border-left: 3px solid var(--accent-dim);
  margin:      1em 0;
  padding:     0.6em 1em;
  background:  var(--bg-alt);
  border-radius: 0 var(--radius) var(--radius) 0;
  color:       var(--text-muted);
  font-size:   0.95em;
}
blockquote strong { color: var(--text); }
blockquote p { margin: 0; }
a { color: var(--link); text-decoration: none; }
a:hover { color: var(--link-hover); text-decoration: underline; }

/* ── Lists ────────────────────────────────────────────── */
.doc-list { margin: 0.5em 0 1em 1.4em; }
.doc-list li { margin-bottom: 0.25em; }

/* ── Inline code ──────────────────────────────────────── */
.inline-code {
  font-family: var(--font-mono);
  font-size:   0.875em;
  background:  var(--bg-code);
  border:      1px solid var(--border);
  padding:     1px 5px;
  border-radius: 4px;
  color:       var(--text-head);
}

/* ── Code blocks ──────────────────────────────────────── */
.code-block {
  position:    relative;
  margin:      1.2em 0;
  border-radius: var(--radius);
  border:      1px solid var(--border);
  background:  var(--bg-code);
  overflow:    hidden;
}
.code-block pre {
  overflow-x:  auto;
  padding:     18px 20px;
  font-family: var(--font-mono);
  font-size:   0.875em;
  line-height: 1.6;
}
.code-block code { font-family: inherit; color: var(--text); }
.code-lang {
  position:   absolute;
  top:        0; right: 44px;
  font-family: var(--font-mono);
  font-size:  11px;
  color:      var(--text-muted);
  padding:    3px 8px;
  background: var(--border);
  border-radius: 0 0 4px 4px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.copy-btn {
  position:   absolute;
  top:        6px; right: 8px;
  background: var(--bg-alt);
  border:     1px solid var(--border);
  border-radius: 4px;
  color:      var(--text-muted);
  cursor:     pointer;
  font-size:  14px;
  padding:    2px 7px;
  transition: color var(--transition), background var(--transition);
}
.copy-btn:hover { color: var(--text); background: var(--border); }
.copy-btn.copied { color: #86efac; }

/* ── Syntax colours ────────────────────────────────────── */
.hl-keyword  { color: var(--hl-keyword);  font-weight: 600; }
.hl-string   { color: var(--hl-string); }
.hl-comment  { color: var(--hl-comment);  font-style: italic; }
.hl-number   { color: var(--hl-number); }
.hl-operator { color: var(--hl-operator); }

/* ── Tables ────────────────────────────────────────────── */
.table-wrap { overflow-x: auto; margin: 1.2em 0; border-radius: var(--radius); border: 1px solid var(--border); }
table { width: 100%%; border-collapse: collapse; font-size: 0.92em; }
thead { background: var(--bg-alt); }
th, td { padding: 9px 14px; text-align: left; border-bottom: 1px solid var(--border); }
th { font-weight: 600; color: var(--text-head); white-space: nowrap; }
tr:last-child td { border-bottom: none; }
tr:hover td { background: var(--bg-alt); }

/* ── Scrollbar styling (webkit) ───────────────────────── */
#toc-list::-webkit-scrollbar, pre::-webkit-scrollbar, .table-wrap::-webkit-scrollbar {
  width: 5px; height: 5px;
}
#toc-list::-webkit-scrollbar-track, pre::-webkit-scrollbar-track, .table-wrap::-webkit-scrollbar-track {
  background: transparent;
}
#toc-list::-webkit-scrollbar-thumb, pre::-webkit-scrollbar-thumb, .table-wrap::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 3px;
}

/* ── Mobile ────────────────────────────────────────────── */
@media (max-width: 768px) {
  #sidebar { display: none; }
  #doc-body { padding: 24px 20px 0; }
  #topbar { padding: 8px 16px; }
}
</style>
</head>
<body>

%s

<div id="content">
  <div id="topbar">
    <button id="theme-toggle" onclick="toggleTheme()" aria-label="Toggle colour scheme">☀ Light</button>
  </div>
  <main id="doc-body">
    %s
  </main>
</div>

<script>
// ── Theme ──────────────────────────────────────────────────
const btn = document.getElementById("theme-toggle");
function applyTheme(t) {
  document.documentElement.setAttribute("data-theme", t);
  btn.textContent = t === "dark" ? "☀ Light" : "☾ Dark";
  localStorage.setItem("lume-theme", t);
}
function toggleTheme() {
  applyTheme(document.documentElement.getAttribute("data-theme") === "dark" ? "light" : "dark");
}
(function() {
  const saved = localStorage.getItem("lume-theme") || "dark";
  applyTheme(saved);
})();

// ── Sidebar search filter ──────────────────────────────────
const searchEl = document.getElementById("sidebar-search");
if (searchEl) {
  searchEl.addEventListener("input", function() {
    const q = this.value.trim().toLowerCase();
    document.querySelectorAll("#toc-list .toc-item").forEach(function(li) {
      const txt = li.textContent.toLowerCase();
      li.style.display = (!q || txt.includes(q)) ? "" : "none";
    });
  });
}

// ── Active TOC highlight on scroll ────────────────────────
const headings = Array.from(document.querySelectorAll(".doc-heading[id]"));
const tocLinks  = document.querySelectorAll(".toc-link");

function onScroll() {
  const scrollY = window.scrollY + 80;
  let active = headings[0];
  for (const h of headings) {
    if (h.offsetTop <= scrollY) active = h;
  }
  tocLinks.forEach(function(a) {
    const isActive = active && a.getAttribute("href") === "#" + active.id;
    a.classList.toggle("active", isActive);
    if (isActive) a.scrollIntoView({ block: "nearest", behavior: "smooth" });
  });
}
window.addEventListener("scroll", onScroll, { passive: true });
onScroll();

// ── Copy button ────────────────────────────────────────────
function copyCode(btn) {
  const code = btn.closest(".code-block").querySelector("code");
  navigator.clipboard.writeText(code.innerText).then(function() {
    btn.textContent = "✓";
    btn.classList.add("copied");
    setTimeout(function() { btn.textContent = "⎘"; btn.classList.remove("copied"); }, 1800);
  });
}
</script>
</body>
</html>
]], escape_html(title), sidebar_html, body_html)
end

-- ── Entry point ───────────────────────────────────────────────────────────────

local src          = read_file(infile)
local body_html, toc = parse_md(src)
local sidebar_html = build_sidebar(toc)

-- extract document title from first h1
local title = src:match("^#%s+(.-)%s*\n") or "Lume Documentation"

local html = build_html(title, sidebar_html, body_html)
write_file(outfile, html)
io.write("lume-docs-build: wrote " .. outfile .. "\n")