require "lib/metaprogramming.nom"
require "lib/operators.nom"
require "lib/utils.nom"

# Conditionals
macro statement [if %condition %if_body] =:
    ".."|if \%condition as lua\ then
        |    \(lua expr "vars.if_body.value") as lua\
        |end

macro statement [if %condition %if_body else %else_body] =:
    ".."|if \%condition as lua\ then
        |    \(lua expr "vars.if_body.value") as lua\
        |else
        |    \(lua expr "vars.else_body.value") as lua\
        |end

# Return
macro statement [return] =: "do return end"
macro block [return %return-value] =: ".."
    |return \%return-value as lua\

macro [do %action] =: ".."
    |(\%action as lua\)(nomsu, setmetatable({}, {__index=vars}))


# GOTOs
macro statement [-> %label] =: ".."
    |::label_\nomsu "var_to_lua_identifier" [%label]\::
macro statement [go to %label] =: ".."
    |goto label_\nomsu "var_to_lua_identifier" [%label]\

# Loop control flow
macro statement [stop, stop loop, break] =: "break"
macro statement [stop for, stop for-loop, break for] =: "goto break_for"
macro statement [stop repeat, stop repeat-loop, break repeat] =: "goto break_repeat"
macro statement [stop %var, break %var] =: ".."
    |goto break_\nomsu "var_to_lua_identifier" [%var]\

macro statement [continue, continue loop] =: "continue"
macro statement [continue for, continue for-loop] =: "goto continue_for"
macro statement [continue repeat, continue repeat-loop] =: "goto continue_repeat"
macro statement [continue %var, go to next %var, on to the next %var] =: ".."
    |goto continue_\nomsu "var_to_lua_identifier" [%var]\

# While loops
macro block [repeat %body] =:
    ".."|while true do
        |    \(lua expr "vars.body.value") as lua\
        |    ::continue_repeat::
        |end
        |::break_repeat::
macro block [repeat while %condition %body] =:
    ".."|while \%condition as lua\ do
        |    \(lua expr "vars.body.value") as lua\
        |    ::continue_repeat::
        |end
        |::break_repeat::
macro block [repeat until %condition %body] =:
    ".."|while not (\%condition as lua\) do
        |    \(lua expr "vars.body.value") as lua\
        |    ::continue_repeat::
        |end
        |::break_repeat::

# Numeric range for loops
macro block [for %var from %start to %stop by %step %body] =:
    %var-type =: lua expr "vars.var.type"
    assert (%var-type == "Var") ".."
        |For loop has the wrong type for the loop variable. Expected Var, but got: \%var-type\
    # This trashes the loop variables, just like in Python.
    ".."
        |for i=\%start as lua\,\%stop as lua\,\%step as lua\ do
        |    \%var as lua\ = i
        |    \(lua expr "vars.body.value") as lua\
        |    ::continue_for::
        |    ::continue_\nomsu "var_to_lua_identifier" [%var]\::
        |end
        |::break_for::
        |::break_\nomsu "var_to_lua_identifier" [%var]\::
macro block [for %var from %start to %stop %body] =:
    %thunk =: :for %var from %start to %stop by 1 %body
    lua block ".."
        |for i,x in ipairs(vars.thunk.value) do
        |    if x.type == 'Var' then vars.thunk.type == vars[x.value] end
        |end
        |return compiler:run_macro(vars.thunk, 'Statement')

macro block [for all %start to %stop by %step %body] =:
    # This trashes the loop variables, just like in Python.
    ".."
        |for i=\%start as lua\,\%stop as lua\,\%step as lua\ do
        |    vars[''] = i
        |    \(lua expr "vars.body.value") as lua\
        |    ::continue_for::
        |    ::continue_\nomsu "var_to_lua_identifier" [%]\::
        |end
        |::break_for::
        |::break_\nomsu "var_to_lua_identifier" [%]\::
macro block [for %var from %start to %stop %body] =:
    %thunk =: :for %var from %start to %stop by 1 %body
    lua block ".."
        |for i,x in ipairs(vars.thunk.value) do
        |    if x.type == 'Var' then vars.thunk.type == vars[x.value] end
        |end
        |return compiler:run_macro(vars.thunk, 'Statement')

macro block [for %var in %iterable %body] =:
    %var-type =: lua expr "vars.var.type"
    assert (%var-type == "Var") ".."
        |For loop has the wrong type for the loop variable. Expected Var, but got: \%var-type\
    # This trashes the loop variables, just like in Python.
    ".."
        |for i,value in ipairs(\%iterable as lua\) do
        |    \%var as lua\ = value
        |    \(lua expr "vars.body.value") as lua\
        |    ::continue_for::
        |    ::continue_\nomsu "var_to_lua_identifier" [%var]\::
        |end
        |::break_for::
        |::break_\nomsu "var_to_lua_identifier" [%var]\::

macro block [for all %iterable %body] =:
    pass # TODO: fix compiler bug
    # This trashes the loop variables, just like in Python.
    ".."|for i,value in ipairs(\%iterable as lua\) do
        |    vars[''] = value
        |    \(lua expr "vars.body.value") as lua\
        |    ::continue_for::
        |    ::continue_\nomsu "var_to_lua_identifier" [%]\::
        |end
        |::break_for::
        |::break_\nomsu "var_to_lua_identifier" [%]\::

# Switch statement/multi-branch if
macro block [when %body] =:
    %result =: ""
    %fallthroughs =: []
    for %statement in (lua expr "vars.body.value.value"):
        %func-call =: lua expr "vars.statement.value"
        assert ((lua expr "vars['func-call'].type") == "FunctionCall") ".."
            |Invalid format for 'when' statement. Only '*' blocks are allowed.
        %tokens =: lua expr "vars['func-call'].value"

        %star =: lua expr "vars.tokens[1]"
        assert (lua expr "vars.star and vars.star.type == 'Word' and vars.star.value == '*'") ".."
            |Invalid format for 'when' statement. Lines must begin with '*'

        %condition =: lua expr "vars.tokens[2]"
        assert %condition ".."
            |Invalid format for 'when' statement. Lines must begin with '*' and have a condition or the word "else"

        %thunk =: lua expr "vars.tokens[3]"
        if (%thunk == (nil)):
            lua block "table.insert(vars.fallthroughs, vars.condition)"
            go to next %statement

        if (lua expr "vars.condition.type == 'Word' and vars.condition.value == 'else'"):
            %result join=: ".."|
                |do
        ..else:
            %condition =: %condition as lua
            for all %fallthroughs: %condition join=: ".."| or \% as lua\
            %result join=: ".."|
                |if \%condition\ then
        %result join=: ".."|
            |    \(lua expr "vars.thunk.value") as lua\
            |    goto finished_when
            |end

        %fallthroughs =: []

    %result join=: "\n::finished_when::"
    %result

# Switch statement
macro block [when %branch-value == ? %body] =:
    %result =: ".."|local branch_value = \%branch-value as lua\
    %fallthroughs =: []
    for %statement in (lua expr "vars.body.value.value"):
        %func-call =: lua expr "vars.statement.value"
        assert ((lua expr "vars['func-call'].type") == "FunctionCall") ".."
            |Invalid format for 'when' statement. Only '*' blocks are allowed.
        %tokens =: lua expr "vars['func-call'].value"

        %star =: lua expr "vars.tokens[1]"
        assert (lua expr "vars.star and vars.star.type == 'Word' and vars.star.value == '*'") ".."
            |Invalid format for 'when' statement. Lines must begin with '*'

        %condition =: lua expr "vars.tokens[2]"
        assert %condition ".."
            |Invalid format for 'when' statement. Lines must begin with '*' and have a condition or the word "else"

        %thunk =: lua expr "vars.tokens[3]"
        if (%thunk == (nil)):
            lua block "table.insert(vars.fallthroughs, vars.condition)"
            go to next %statement

        if (lua expr "vars.condition.type == 'Word' and vars.condition.value == 'else'"):
            %result join=: ".."|
                |do
        ..else:
            %condition =: ".."|branch_value == (\%condition as lua\)
            for all %fallthroughs: %condition join=: ".."| or (branch_value == \% as lua\)
            %result join=: ".."|
                |if \%condition\ then
        %result join=: ".."|
            |    \(lua expr "vars.thunk.value") as lua\
            |    goto finished_when
            |end

        %fallthroughs =: []

    %result join=: "\n::finished_when::"
    %result