#!/usr/bin/env nomsu -V2.5
use "core"
use "lib/os.nom"

%UPGRADES = {}
action [upgrade to %version via %upgrade_fn]:
    %UPGRADES.%version = %upgrade_fn

%ACTION_UPGRADES = {}
action [upgrade action %stub to %version via %upgrade_fn]:
    unless (%ACTION_UPGRADES.%version): %ACTION_UPGRADES.%version = []
    %ACTION_UPGRADES.%version.%stub = %upgrade_fn

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

compile [upgrade action %action to %version as %body] to:
    %replacements = {}
    for %i in 1 to (length of %action):
        if (%action.%i.type is "Var"):
            %replacements.(%action.%i.1) = "\(\%tree as lua id)[\%i]"
    local action [make tree %t]:
        when:
            (%t is "Var" syntax tree):
                if (%replacements.(%t.1)):
                    return %replacements.(%t.1)
                ..else:
                    return "\(%t.type)(\(quote "\(%t.source)"), \(quote "\(%t.1) \0\(=lua "string.format('%X', __MANGLE_INDEX)")"))"
            (%t is syntax tree):
                %args = ((make tree %) for % in %t)
                add "\(\%tree as lua id).source" to %args at index 1
                return "\(%t.type)(\(%args joined with ", "))"
            else: return (quote "\%t")
    return (..)
        Lua ".."
            A_upgrade_action_1_to_2_via_3(\(quote %action.stub), \(%version as lua expr), function(\(\%tree as lua id))
                __MANGLE_INDEX = (__MANGLE_INDEX or 0) + 1
                return \(make tree %body)
            end)

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 % in %ver matching "[0-9]+")
    %versions = {}
    for %v = % in %UPGRADES: %versions.%v = (yes)
    for %v = % in %ACTION_UPGRADES: %versions.%v = (yes)
    %versions = ((keys in %versions) 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
        if %ACTION_UPGRADES.%ver:
            %tree = (..)
                %tree with % -> (..)
                    if ((% is "Action" syntax tree) and %ACTION_UPGRADES.%ver.(%.stub)):
                        return (call %ACTION_UPGRADES.%ver.(%.stub) with [%])
        if %UPGRADES.%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 or (Nomsu version)) to %end_version

parse [%tree upgraded] as (%tree upgraded from (%tree.version or (Nomsu 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