#!/usr/bin/env nomsu -V1
use "core"
use "lib/os.nom"

%UPGRADES <- {}

action [upgrade to %version via %upgrade_fn]
    %UPGRADES.%version <- %upgrade_fn

parse [upgrade %tree to %version as %body] as
    upgrade to %version via ([%] -> (% with %tree -> %body))

action [%tree upgraded from %start_version to %end_version, %tree upgraded to %end_version from %start_version]
    local action [%ver as list]
        (% as number) for % where %ver matches "[0-9]+"
    
    %versions <-: (keys in %UPGRADES) sorted by % -> (% as list)
    for %ver in %versions
        if: (%ver as list) <= (%start_version as list)
            do next %ver
        if: (%ver as list) > (%end_version as list)
            stop %ver
        %tree <- (call %UPGRADES.%ver with [%tree])
    return %tree

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
parse [%tree upgraded from %start_version] as: %tree upgraded from %start_version to (Nomsu version)
parse [%tree upgraded to %end_version] as: %tree upgraded from %tree.version to %end_version
parse [%tree upgraded] as: %tree upgraded from %tree.version to (Nomsu version)

action [use %path from version %version]
    for file %filename in %path
        if (=lua "LOADED[\%filename]")
            do next %filename
        %file <-: read file %filename
        %tree <-: parse %file from %filename
        %tree <-: upgrade %tree from %version
        run tree %tree