require "upath"
require "proto"
local lua_action = Object:clone()


-- set type=lua_action metadata for path
function lua_action:register(path)
    dump("acl_check",path, "lua_action")
    assert(self.session:acl_check(path, "lua_action"), "EACCESS:May not use lua_action on path")
    self.session:meta_reset(path, "type", "type", "lua_action")
end


function lua_action:unregister(path)
    self.session:meta_delete(path, "type", "type", "lua_action")
end


-- validate file
-- return false or nil will just ignore this type
function lua_action:check(path)
    return true
end


-- remove all dependency relations which where previously recorded for path
function lua_action:abolish(path)
end


function lua_action:discover(path)
    -- require ?
end


-- compile path to destpath
function lua_action:compile(path, destpath)
end

-- figures out what kind of changes are from old to new (maybe with the help of scm)
-- intended types (the exact interpretation is open to the type):
--   "none"       did not changed anything
--   "edit"       mixed edit
--   "prepend"    user prepended only
--   "append"     user appended only
--   "add"        only content added but nothing removed
--   "comment"    commented only
--   "commentadd" added comment only
--   "spam"       detected spam
-- currentfile the current file
-- newfile     the new file
-- return a string describing the kind (required sub-permission), returning nil will not yield in a acl check and permit anything
function lua_action:diffkind(currentfile, newfile)
    local diff = io.popen("diff -d -C1 %old% %new%" % { old = currentfile:sanitize('shquote'), new = newfile:sanitize('shquote')})

    local changestat = {
        comment = {added = 0, changed = 0},
        content = {added = 0, changed = 0},
        prepend = 'unknown', append = 'unknown',
        changes = 0
    }

    for line in diff:lines() do
        local mode,content = line:match('^(.) (.*)')

        if mode then
            -- this pattern is slightly broken as it will detect empty comment lines (//) as content
            local kind = (content:find('^%s*--')) and "comment" or "content"

            if mode == '+' then
                -- TODO rxpd spamcheck here, per kind?
                changestat[kind].added = changestat[kind].added + 1
                changestat.changes = changestat.changes + 1
                if changestat.prepend == 'unknown' then changestat.prepend = 'maybe' end
                if changestat.append == 'unknown' then changestat.append = 'maybe' end
            elseif mode == '!' then
                -- TODO rxpd spamcheck here, per kind?
                changestat[kind].changed = changestat[kind].changed + 1
                changestat.changes = changestat.changes + 1
                changestat.prepend = false
                changestat.append = false
            elseif mode == '-' then
                changestat[kind].changed = changestat[kind].changed + 1
                changestat.changes = changestat.changes + 1
                changestat.prepend = false
                changestat.append = false
            elseif mode == ' ' then
                if changestat.prepend == 'unknown' then changestat.prepend = false end
                if changestat.append == 'maybe' then changestat.append = false end
            end
        end
    end

    diff:close()

    -- now analyze the stats
    local result

    if changestat.changes == 0 then
        -- nothing changed
        result = 'none'
    else
        if changestat.content.added == 0 and changestat.content.changed == 0 then
            if changestat.comment.changed == 0 then
                -- only comments added
                result = 'commentadd'
            else
                -- edit in comment
                result = 'comment'
            end
        else

            if changestat.append == 'maybe' then
                -- only added new content at the end
                result = 'append'
            elseif changestat.prepend == 'maybe' then
                -- only added new content at the begin
                result = 'prepend'
            elseif changestat.content.changed == 0 then
                -- only new content added
                result = 'add'
            else
                -- generic edit
                result = 'edit'
            end
        end
    end

    return result
end


return lua_action

-- Local Variables:
-- mode: lua
-- lua-indent-level: 4
-- indent-tabs-mode: nil
-- End: