#!/usr/bin/env lua

--- Transforms a code into a list of file to stitch
---@param code string the code to parse
---@return table
local function parse(code)
    if type(code) ~= "string" then error("parse expects a string") end
    local filemap = {
        ["1"] = "1.wav",
        ["2"] = "2.wav",
        ["3"] = "3.wav",
        ["4"] = "4.wav",
        ["5"] = "5.wav",
        ["6"] = "6.wav",
        ["7"] = "7.wav",
        ["8"] = "8.wav",
        ["9"] = "9.wav",
        ["0"] = "0.wav",
        ["*"] = "Star.wav",
        ["#"] = "Octothorpe.wav",
        ["A"] = "A.wav",
        ["B"] = "B.wav",
        ["C"] = "C.wav",
        ["D"] = "D.wav",
        ["-"] = "skip.wav",
    }
    local seq = {}
    for i = 1, #code do
        table.insert(seq, filemap[code:sub(i, i)] or filemap["-"])
    end
    return seq
end



local args = {...}

local i = 1
while i <= #args do
    local code = args[i]
    local out = args[i+1] or "out.wav"
    local sequence = parse(code)
    local list = io.open(out .. ".filelist", "w")
    if not list then
        io.stderr:write("Cannot open `" .. out .. ".filelist\n")
        io.stderr:write("Abborting\n")
        os.exit(1)
    end
    for _, v in ipairs(sequence) do
        list:write("file '" .. v .. "'\n")
    end
    list:close()
    os.execute("ffmpeg -f concat -safe 0 -i " .. out .. ".filelist -c copy " .. out)
    i = i + 2
end