-- $Id$

-- Garrett Albright's Ultimate Lua Script for running Drupal on Lighty!
-- This script handles URL rewriting, WWW addition/removal, and Boost support
-- for Drupal installations running on the lighttpd web server daemon. These are
-- tasks which would be handled by ".htaccess" files when running on the Apache
-- server. Discuss this script at: http://groups.drupal.org/node/25453

-- For more information on how to use this script on your server, see:
-- http://redmine.lighttpd.net/projects/lighttpd/wiki/Docs:ModMagnet

-- Configuration:
--   "www" addition/removal: If you want this script to ADD the "www." prefix
--   to the host name when requests are made to the server without it, set the
--   "love_www" value to "true" (without quotes). This will cause requests for
--   "http://example.com/" to be redirected to "http://www.example.com/". If
--   you want it to REMOVE the prefix when requests are made to the server WITH
--   it, set the value to "false"; "http://www.example.com/" will be redirected
--   to "http://example.com/". If you don't want to do any redirection either
--   way, set the value to "nil".

love_www = nil

--   Subdirectory: If your Drupal installation is in a subdirectory - for
--   example, at http://example.com/drupal/ instead of just
--   http://example.com/ - set the d_path variable below to the path to that
--   directory, with a slash at the beginning AND at the ending of the path. For
--   the example above, you would set d_path to '/drupal/' (with quotes). If
--   your Drupal installation is at your web site's root - for example, just at
--   http://example.com/ - set this variable to a single slash: '/'

d_path = '/' 

--   Boost support: Set to "true" (without quotes) to enable rewriting necessary
--   for the Boost module. Set to "false" if you're not using Boost.
--   See also: http://drupal.org/node/150909

boost_on = true

--   Boost path header: If set to "true", Boost will add a "X-Boost-Path" HTTP
--   header to Boost cache-worthy requests which either contains the path to
--   the cache file in the case of a cache hit, or the word "miss" in the case
--   of a cache miss. This may be handy when initially setting up or debugging
--   Boost, but you may wish to turn it off (set to "false") for live sites for
--   security reasons.

boost_header = true

-- ---- Stop! You should not need to edit anything else below this line. ---- --

-- Remove "www" from URLs. Note that unlike the .htaccess file that comes with
-- Drupal, you don't have to edit this to add your site's/sites' URL/URLs - we
-- can determine that automatically. See also: http://drupal.org/node/352180
-- Match "www." at the beginning of the URL.
-- Note that Lua's matching system is inspired by standard regular
-- expressions, but is not a drop-in replacement. In this case it's close
-- enough, though. See: http://www.lua.org/manual/5.1/manual.html#5.4.1
-- The match function returns nil when there's no match.

if love_www == false and lighty.env['uri.authority']:match('^www%.') ~= nil then
  -- Rebuild the URL without the "www." and pass it as the "Location" header.
  -- Note that Lua's string counting functions are 1-based (the first character
  -- is at position 1, not position 0 as in most other languages), so the 5
  -- parameter is correct for the sub() function below.
  lighty.header['Location'] = lighty.env['uri.scheme'] .. '://' .. lighty.env['uri.authority']:sub(5) .. lighty.env['request.orig-uri']

  -- Return HTTP status code 301.
  return 301
end

-- Add "www" to URLs. Read the comments in the "Remove 'www'" section above for
-- more info - much of it could be repeated here.

if love_www and lighty.env['uri.authority']:match('^www%.') == nil then
  -- Rebuild URL, adding "www.", and pass it in as the "Location" header.
  lighty.header['Location'] = lighty.env['uri.scheme'] .. '://www.' .. lighty.env['uri.authority'] .. lighty.env['request.orig-uri']
  return 301
end

-- We don't want directories (such as the root document directory when '/' is
-- requested) to be counted as a "file" just because it will respond to
-- lighty.stat() with something other than nil. This bit of ugliness lets us do
-- so without creating another variable to store the results of lighty.stat()
-- and then doing file_exists = stat ~= nil and stat.is_file
local file_exists = lighty.env['physical.path']:sub(-1) ~= '/' and lighty.stat(lighty.env['physical.path']) ~= nil
local path_trimmed = lighty.env['uri.path']:sub(d_path:len() + 1)

if boost_on then
  if file_exists then
    -- If the file exists, only try to Boost JS and CSS files (not images or
    -- anything else). This naively assumes all CSS and JS requests will use
    -- their normal extensions, but maybe Boost is using the same assumption…?
    ext = path_trimmed:match('%.%a+')
    if ext ~= '.js' and ext ~= '.css' then
      return
    end
  end
  --[[
    Check for the existence of files at physical paths.
    
    @param paths
      A table of path info to check, keyed by physical path.
    @return
      true if a file exists at a path in the table; false otherwise.
  --]]
  local check_exists = function(paths)
    for idx, stats in ipairs(paths) do
      if lighty.stat(stats.physical) then
        lighty.env['physical.path'] = stats.physical
        lighty.env['uri.path'] = stats.path
        lighty.env['physical.rel-path'] = stats.path
        lighty.header['Content-Type'] = stats.ctype
        if stats.gzip then
          lighty.header['Content-Encoding'] = 'gzip'
        end
        if boost_header then
          lighty.header['X-Boost-Path'] = stats.path
        end
        return true
      end
    end
    return false
  end

  -- Make sure there's something in the Cookie value to avoid having to check
  -- against nil more than once
  if (lighty.request['Cookie'] == nil) then
    lighty.request['Cookie'] = ''
  end
  
  local gzip_on = (lighty.request['Accept-Encoding'] ~= nil and lighty.request['Accept-Encoding']:find('gzip', 1, true)) or lighty.request['Cookie']:find('boost-gzip', 1, true)

  -- cache/perm files might exist in their non-cache location (in which case,
  -- file_exists == true at this point), but even in that case we want to serve
  -- them from the cache directory anyway (for ghetto Gzip support, for
  -- example).
  local perm = {}

  if path_trimmed == 'boost-gzip-cookie-test.html' then
    -- For whatever reason, OOP-style function calling isn't working on these
    -- tables (perm:insert(item) causes the error "attempt to call method
    -- 'insert' (a nil value)"), so we do it functional-style.
    table.insert(perm, {
      ['physical'] = lighty.env['physical.doc-root'] .. d_path .. 'cache/perm/boost-gzip-cookie-test.html.gz',
      ['ctype'] = 'text/html',
      ['path'] = d_path .. 'cache/perm/boost-gzip-cookie-test.html.gz',
      ['gzip'] = true,
    })
  elseif ext ~= nil then
    local path = d_path .. 'cache/perm/' .. lighty.env['uri.authority'] .. '/' .. path_trimmed .. '_' .. ext
    local physical = lighty.env['physical.doc-root'] .. path
    local types = {
      ['.css'] = 'text/css',
      ['.js'] = 'text/javascript',
    }
    if gzip_on then
      table.insert(perm, {
        ['physical'] = physical .. '.gz',
        ['ctype'] = types[ext],
        ['path'] = path .. '.gz',
        ['gzip'] = true,
      })
    end
    table.insert(perm, {
      ['physical'] = physical,
      ['ctype'] = types[ext],
      ['path'] = path,
      ['gzip'] = false,
    })
  end
  
  boost_hit = #perm ~= 0 and check_exists(perm)
  
  -- If no hits yet, and we might have a hit in cache/normal…
  if not boost_hit then
    if file_exists then
      -- Just serve the file!
      return
    end
    -- Patterns for paths Boost doesn't cache. Lua's patterns lack an "or"
    -- operator like the pipe in regular expressions, so instead of something
    -- like '^(admin|cache|etc)' we have this kludge.
    for idx, path in ipairs({
      '^admin',
      '^cache',
      '^misc',
      '^modules',
      '^sites',
      '^system',
      '^openid',
      '^themes',
      '^node/add',
      '^comment/reply',
      '^edit',
      '^user$',
      '^user/[^%d]',
    }) do
      if path_trimmed:match(path) then
        bad_path = true
        break
      end
    end
    if not bad_path == true and lighty.env['request.method'] == 'GET' and lighty.env['uri.scheme'] ~= 'https' and lighty.request['Cookie']:find('DRUPAL_UID', 1, true) == nil then
      local path = d_path .. 'cache/normal/' .. lighty.env['uri.authority'] .. '/' .. path_trimmed .. '_'
      if lighty.env['uri.query'] ~= nil then
        path = path .. lighty.env['uri.query']
      end
      local physical = lighty.env['physical.doc-root'] .. path
      local types = {
        {
          ['ext'] = '.html',
          ['ctype'] = 'text/html',
        },
        {
          ['ext'] = '.xml',
          ['ctype'] = 'text/xml',
        },
        {
          ['ext'] = '.json',
          ['ctype'] = 'text/javascript',
        },
      }
      local norm = {}
      
      if gzip_on then
        -- Similarly to above, types:ipairs() does not work
        for idx, type in ipairs(types) do
          table.insert(norm, {
            ['physical'] = physical .. type.ext .. '.gz',
            ['ctype'] = type.ctype,
            ['path'] = path .. type.ext .. '.gz',
            ['gzip'] = true,
          })
        end
      end
      for idx, type in ipairs(types) do
        table.insert(norm, {
          ['physical'] = physical .. type.ext,
          ['ctype'] = type.ctype,
          ['path'] = path .. type.ext,
          ['gzip'] = false,
        })
      end
      
      -- Check the norm for hits
      boost_hit = check_exists(norm)
    end
  end
  -- If we got a hit and we want to send the header…
end

if not file_exists and (not boost_on or not boost_hit) then
  -- Rewrite the query part of the URI (or create it if there isn't one) to
  -- append "q=<path>" (while stripping away the path to the Drupal installation
  -- if it's in there).
  lighty.env['uri.query'] = (lighty.env['uri.query'] == nil and '' or lighty.env['uri.query'] .. '&') .. 'q=' .. path_trimmed
  lighty.env['uri.path'] = d_path .. 'index.php'
  lighty.env['physical.rel-path'] = lighty.env['uri.path']
  lighty.env['physical.path'] = lighty.env['physical.doc-root'] .. lighty.env['physical.rel-path']
end