-- configuration handling for texdoc
--[[ 
Copyright 2008, 2009 Manuel Pégourié-Gonnard
Distributed under the terms of the GNU GPL version 3 or later.
See texdoc.tlu for details.
--]]

-- Load a private environment for this submodule (see texdoc.tlu).
local L = {}
load_env(L, {
    'config',
})

--[[ structure of the alias table

alias = {
  name1 = { <true or nill> stop, <aliasentry> aliasentry1, ... },
  ...
}
stop == true means further alias directives should be ignored

aliasentry = {
  name      = <string> pattern to be matched,
  score     = <number or nil> associated score,
  original  = <true or nil> is this the original keyword?,
  locale    = <true or nil> is this entry found via config.lang?
}
score == nil means to use the default score (defined in score.tlu)

--]]

-- alias is local to this file
local alias = {}

-- turn a name into a suitable alias entry
-- if score is 'false', this is the original name
function make_alias(pat, score)
    local al = {}
    al.name = pat
    if score == false then
        al.original = true
    else
        al.score = score -- may be nil
    end
    return al
end

-- add an alias value for a key
function add_alias(key, value, score)
    local k = string.lower(key)
    alias[k] = alias[k] or { make_alias(key, false) }
    if alias[k].stop then return end
    table.insert(alias[k], make_alias(value, score))
end

-- prevent a key from begin further aliased
function stop_alias(key)
    local k = string.lower(key)
    alias[k] = alias[k] or {}
    alias[k].stop = true
end

-- get patterns for a name
function get_patterns(name, no_alias)
    local n = string.lower(name)
    -- get normal aliases
    local res
    if config.mode ~= 'regex' and config.alias_switch
        and not no_alias and alias[n] then
        res = alias[n]
    else
        res = { make_alias(name, false) }
    end
    -- check for language-specific aliases
    local lang = config.lang and alias[n .. '-' .. config.lang]
    if lang then
        for _, entry in ipairs(lang) do
            if not entry.original then
                table.insert(res, {
                    name    = entry.name,
                    score   = entry.score,
                    locale  = true,
                })
            end
        end
    end
    return res
end

-- interpret a confline as an alias setting or return false
function confline_to_alias(line, file, pos)
    -- alias directive without score
    local key, val = string.match(line, '^alias%s+([%w%p]+)%s*=%s*(.+)')
    if key and val then
        add_alias(key, val)
        return true
    end
    -- alias directive with score
    local score, key, val = string.match(line,
        '^alias%(([%d+-.]+)%)%s+([%w%p]+)%s*=%s*(.+)')
    if score then score = tonumber(score) end
    if key and val and score then
        add_alias(key, val, score)
        return true
    end
    -- stopalias directive
    local key = string.match(line, '^stopalias%s+(.+)')
    if key then 
        stop_alias(key)
        return true
    end
    return false
end

-- iterator over the list of keys in the alias table
function aliased_names()
    return function(_, cur)
        return (next(alias, cur))
    end
end

-- finally export a few symbols
export_symbols(L, {
    'confline_to_alias',
    'get_patterns',
    'aliased_names',
})