-- @@SHEBANG
-- -*- Lua -*-
-- gitano-update-hook
--
-- Git (with) Augmented network operations -- Update hook handler
--
-- Copyright 2012 Daniel Silverstone <dsilvers@digital-scurf.org>
--
--

-- @@GITANO_LUA_PATH

local gitano = require "gitano"
local gall = require "gall"
local luxio = require "luxio"
local sio = require "luxio.simple"
local sp = require "luxio.subprocess"

-- @@GITANO_BIN_PATH
-- @@GITANO_SHARE_PATH
-- @@GITANO_PLUGIN_PATH

local refname, oldsha, newsha = ...

local start_log_level = gitano.log.get_level()
-- Clamp level at info until we have checked if the caller
-- is an admin or not
gitano.log.cap_level(gitano.log.level.INFO)
gitano.log.syslog.open()

local nullsha = ("0"):rep(40)

local repo_root = luxio.getenv("GITANO_ROOT")
local username  = luxio.getenv("GITANO_USER") or "gitano/anonymous"
local keytag    = luxio.getenv("GITANO_KEYTAG") or "unknown"
local project   = luxio.getenv("GITANO_PROJECT") or ""
local source    = luxio.getenv("GITANO_SOURCE") or "ssh"

-- Now load the administration data
gitano.config.repo_path(repo_root)
local admin_repo = gall.repository.new((repo_root or "") .. "/gitano-admin.git")

if not admin_repo then
   gitano.log.fatal("Unable to locate administration repository.  Cannot continue");
end

local admin_head = admin_repo:get(admin_repo.HEAD)

if not admin_head then
   gitano.log.fatal("Unable to find the HEAD of the administration repository.  Cannot continue");
end

local config, msg = gitano.config.parse(admin_head)

if not config then
   gitano.log.critical("Unable to parse administration repository.")
   gitano.log.critical("  * " .. (msg or "No error?"))
   gitano.log.fatal("Cannot continue")
end

-- Now, are we an admin?
if config.groups["gitano-admin"].filtered_members[username] then
   -- Yep, so blithely reset logging level
   gitano.log.set_level(start_log_level)
end

if not config.global.silent then
   -- Not silent, bump to chatty level automatically
   gitano.log.bump_level(gitano.log.level.CHAT)
end

local repo, msg = gitano.repository.find(config, project)
if not repo then
   gitano.log.critical("Unable to locate repository.")
   gitano.log.critical("  * " .. (tostring(msg)))
   gitano.log.fatal("Cannot continue")
end
   
if repo.is_nascent then
   gitano.log.fatal("Repository " .. repo.name .. " is nascent")
end


-- Prepare an update operation

local context = {
   ["source"] = source,
   ["ref"] = refname,
   ["oldsha"] = oldsha,
   ["newsha"] = newsha,
   ["user"] = username,
}

-- Attempt to work out what's going on regarding the update.

if oldsha == nullsha and newsha ~= nullsha then
   context["operation"] = "createref"
elseif oldsha ~= nullsha and newsha == nullsha then
   context["operation"] = "deleteref"
else
   local base, msg = repo.git:merge_base(oldsha, newsha)
   if not base then
      gitano.log.fatal(msg)
   elseif (base == true) or ((base) and (base == newsha)) then
      context["operation"] = "updaterefnonff"
   else
      context["operation"] = "updaterefff"
   end
end

-- Populate the trees

local function do_expensive_populate_context(context)

   local oldtree, newtree
   if oldsha == nullsha or newsha == nullsha then
      repo.git:force_empty_tree()
   end

   if oldsha == nullsha then
      oldtree = repo.git:get(gall.tree.empty_sha).content
   else
      local thing = repo.git:get(oldsha)
      if thing.type == "tag" then
	 thing = thing.content.object
      end
      if thing.type == "commit" then
	 oldtree = thing.content.tree.content
      else
	 oldtree = repo.git:get(gall.tree.empty_sha).content
	 gitano.log.warn("Odd, old object", oldsha, "is not a commit or tag")
      end
   end

   if newsha == nullsha then
      newtree = repo.git:get(gall.tree.empty_sha).content
   else
      local thing = repo.git:get(newsha)
      if thing.type == "tag" then
	 thing = thing.content.object
      end
      if thing.type == "commit" then
	 newtree = thing.content.tree.content
      else
	 newtree = repo.git:get(gall.tree.empty_sha).content
	 gitano.log.warn("Odd, new object", oldsha, "is not a commit or tag")
      end
   end

   -- First, populate gitano/starttree and gitano/targettree

   local function set_list(tag, entries)
      -- Make the set for direct string tests
      for i = 1, #entries do
	 entries[entries[i]] = true
      end
      context[tag] = entries
   end

   local function populate_tree(tag, tree)
      local flat_tree = gall.tree.flatten(tree)
      local names = {}
      for fn in pairs(flat_tree) do
	 names[#names+1] = fn
      end
      set_list(tag, names)
   end

   populate_tree("start_tree", oldtree)
   populate_tree("target_tree", newtree)

   -- Now gitano/treedelta
   local delta = oldtree:diff_to(newtree)
   local targets, added, deleted, modified, renamed, renamedto =
      {}, {}, {}, {}, {}, {}

   for i = 1, #delta do
      local details = delta[i]
      local fname = details.filename
      targets[#targets+1] = fname
      if details.action == "A" then
	 added[#added+1] = fname
      end
      if details.action == "C" and details.score == "100" then
	 added[#added+1] = fname
      end
      if details.action == "D" then
	 deleted[#deleted+1] = fname
      end
      if details.action == "M" or
	 ((details.action == "R" or details.action == "C") and
	  (tonumber(details.score) < 100)) then
	 modified[#modified+1] = fname
      end
      if details.action == "R" then
	 renamed[#renamed+1] = details.src_name
	 renamedto[#renamedto+1] = fname
      end

      context["treediff/kind/" .. fname] = details.endkind
      context["treediff/oldkind/" .. fname] = details.startkind
   end

   set_list("treediff/targets", targets)
   set_list("treediff/added", added)
   set_list("treediff/deleted", deleted)
   set_list("treediff/modified", modified)
   set_list("treediff/renamed", renamed)
   set_list("treediff/renamedto", renamedto)
end

local function defer_generation(key)
   context[key] = function(ctx)
		     -- This populates quite a bit, so we do this
		     -- test in case someone else got hold of this
		     -- beforehand and manages to cross the streams
		     if type(ctx[key]) == "function" then
			gitano.log.chat("Treedeltas generating because of:",
					key, " Please hold.")
			do_expensive_populate_context(ctx)
			gitano.log.chat("Treedeltas built, continuing")
		     end
		     -- And return what we were meant to be
		     return ctx[key]
		  end
end

defer_generation "start_tree"
defer_generation "target_tree"
defer_generation "treediff/targets"
defer_generation "treediff/added"
defer_generation "treediff/deleted"
defer_generation "treediff/modified"
defer_generation "treediff/renamed"
defer_generation "treediff/renamedto"

-- Run the ruleset given the contextet

local action, reason = repo:run_lace(context)

if not action then
   gitano.log.crit(reason)
   gitano.log.fatal("Ruleset did not complete cleanly")
end

if action ~= "allow" then
   gitano.log.critical("Rules refused update:", reason)
   gitano.log.fatal("Ruleset denied action.  Sorry")
end

-- Now perform any special hook checks (e.g. for the admin hook)
gitano.log.ddebug("Ruleset allowed the action, let's run builtin action")

local allow, msg = gitano.actions.update_actions(conf, repo, context)
if not allow then
   gitano.log.critical("Builtin actions said:", msg)
   gitano.log.fatal("Actions denied action.  Sorry")
end

if repo:uses_hook("update") then
   gitano.log.debug("Configuring for update hook")
   gitano.actions.set_supple_globals("update")

   local msg = "Running repository update hook"
   gitano.log.info(msg)
   gitano.syslog.info(msg)

   local info = {
      username = username,
      keytag = keytag,
      source = source,
      realname = (config.users[username] or {}).real_name or "",
      email = (config.users[username] or {}).email_address or "",
   }
   local ok, msg = gitano.supple.run_hook("update", repo, info,
					  refname, oldsha, newsha)
   if not ok then
      gitano.log.fatal(msg or "No reason given to refuse action.")
   end
   gitano.log.info("Finished")
end

gitano.log.info("Allowing ref update of", 
		refname, "from", oldsha, "to", newsha)

gitano.log.syslog.info("Allowing ref update of", refname)

gitano.log.syslog.close()

return 0