-- texdoclib-alias.tlu: alias handling for texdoc
--
-- The TeX Live Team, GPLv3, see texdoclib.tlu for details

--[[ structure of the alias table

alias = {
  name1 = {<true or nil> 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 texdoclib-score.tlu)

--]]

-- dependencies
local texdoc = {
    config = require 'texdoclib-config',
}

-- shortcuts
local M = {}

-- 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
local 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
local function add_alias(key, value, score)
    local k = key:lower()
    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 being further aliased
local function stop_alias(key)
    local k = key:lower()
    alias[k] = alias[k] or {}
    alias[k].stop = true
end

-- get patterns for a name
function M.get_patterns(name, no_alias)
    local n = name:lower()

    -- get normal aliases
    local res
    if alias[n] and not no_alias then
        res = alias[n]
    else
        res = {make_alias(name, false)}
    end

    -- check for language-specific aliases
    local config_lang = texdoc.config.get_value('lang')
    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 M.confline_to_alias(line)
    -- alias directive without score
    local key, val = line:match('^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 = line:match('^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 = line:match('^stopalias%s+(.+)')
    if key then
        stop_alias(key)
        return true
    end
    return false
end

-- iterator over the list of keys in the alias table
-- Note: currently this function is not used (for debug)
function M.aliased_names()
    return function(_, cur)
        return (next(alias, cur))
    end
end

return M

-- vim: ft=lua:
