# Rule for making rules
lua block ".."
    |compiler:def("rule %spec %body", function(compiler, vars)
    |    return compiler:def(vars.spec, vars.body)
    |end)

# Macros
rule "macro %spec %body":
    lua block ".."
        |compiler:defmacro(vars.spec, vars.body)

rule "macro block %spec %body":
    lua block ".."
        |do
        |    local spec, body = vars.spec, vars.body
        |    local wrapper = function(compiler, vars, kind)
        |        if kind == "Expression" then
        |            compiler:error("Macro: "..spec.." was defined to be a block, but is being used as an expression.")
        |        end
        |        return body(compiler, vars, kind), true
        |    end
        |    compiler:defmacro(spec, wrapper)
        |    return nil
        |end

# Compiler tools
rule ["eval %code", "run %code"]:
    lua expr "compiler:run(vars.code)"

macro "source code %code":
    lua expr "utils.repr(vars.code.src, true)"

rule "run file %filename":
    lua block ".."
        |do
        |    local file = io.open(vars.filename)
        |    return compiler:run(file:read("*a"))
        |end

# Macro helper functions
rule "%tree as lua block":
    lua block [..]
        "do return compiler:tree_to_lua(", %tree, ", 'Statement'), true end"

rule "%tree as lua expr":
    lua expr [..]
        "compiler:tree_to_lua(", %tree, ", 'Expression')"

# String functions
rule "join %strs":
    lua block ".."
        |local str_bits = {}
        |for i,bit in ipairs(vars.strs) do str_bits[i] = utils.repr(bit) end
        |do return table.concat(str_bits) end

rule "join %strs with glue %glue":
    lua block ".."
        |local str_bits = {}
        |for i,bit in ipairs(vars.strs) do str_bits[i] = utils.repr(bit) end
        |do return table.concat(str_bits, vars.glue) end

rule ["capitalize %str", "%str capitalized"]:
    lua expr ".."|vars.str:gsub("%l", string.upper, 1)

# Variable assignment
macro block "let %varname = %value":
    ".."|vars[\%varname as lua expr\] = \%value as lua expr\

# Operators
macro ["true","yes"]: "true"
macro ["false","no"]: "false"
macro ["nil","null"]: "nil"
macro block ["nop", "pass"]: ""
macro "%a + %b": ".."|(\%a as lua expr\ + \%b as lua expr\)
macro "%a + %b + %c": ".."|(\%a as lua expr\ + \%b as lua expr\ + \%c as lua expr\)
macro "%a + %b + %c + %d": ".."|(\%a as lua expr\ + \%b as lua expr\ + \%c as lua expr\ + \%d as lua expr\)
macro "%a - %b": ".."|(\%a as lua expr\ - \%b as lua expr\)
macro "%a * %b": ".."|(\%a as lua expr\ * \%b as lua expr\)
macro "%a * %b * %c": ".."|(\%a as lua expr\ * \%b as lua expr\ * \%c as lua expr\)
macro "%a * %b * %c * %d": ".."|(\%a as lua expr\ * \%b as lua expr\ * \%c as lua expr\ * \%d as lua expr\)
macro "%a / %b": ".."|(\%a as lua expr\ / \%b as lua expr\)
macro "%a === %b": ".."|(\%a as lua expr\ == \%b as lua expr\)
macro "%a !== %b": ".."|(\%a as lua expr\ ~= \%b as lua expr\)
macro "%a < %b": ".."|(\%a as lua expr\ < \%b as lua expr\)
macro "%a < %b < %c": ".."|((\%a as lua expr\ < \%b as lua expr\) and (\%b as lua expr\ < \%c as lua expr\))
macro "%a <= %b < %c": ".."|((\%a as lua expr\ <= \%b as lua expr\) and (\%b as lua expr\ < \%c as lua expr\))
macro "%a <= %b <= %c": ".."|((\%a as lua expr\ <= \%b as lua expr\) and (\%b as lua expr\ <= \%c as lua expr\))
macro "%a < %b <= %c": ".."|((\%a as lua expr\ < \%b as lua expr\) and (\%b as lua expr\ <= \%c as lua expr\))
macro "%a > %b > %c": ".."|((\%a as lua expr\ > \%b as lua expr\) and (\%b as lua expr\ > \%c as lua expr\))
macro "%a >= %b > %c": ".."|((\%a as lua expr\ >= \%b as lua expr\) and (\%b as lua expr\ > \%c as lua expr\))
macro "%a >= %b >= %c": ".."|((\%a as lua expr\ >= \%b as lua expr\) and (\%b as lua expr\ >= \%c as lua expr\))
macro "%a > %b >= %c": ".."|((\%a as lua expr\ > \%b as lua expr\) and (\%b as lua expr\ >= \%c as lua expr\))
macro "%a <= %b": ".."|(\%a as lua expr\ <= \%b as lua expr\)
macro "%a > %b": ".."|(\%a as lua expr\ > \%b as lua expr\)
macro "%a >= %b": ".."|(\%a as lua expr\ >= \%b as lua expr\)
macro "%a ^ %b": ".."|(\%a as lua expr\ ^ \%b as lua expr\)
macro "%a and %b": ".."|(\%a as lua expr\ and \%b as lua expr\)
macro "%a and %b and %c":
    ".."|(\%a as lua expr\ and \%b as lua expr\ and \%c as lua expr\)
macro "%a and %b and %c and %d":
    ".."|(\%a as lua expr\ and \%b as lua expr\ and \%c as lua expr\ and \%d as lua expr\)
macro "%a or %b": ".."|(\%a as lua expr\ or \%b as lua expr\)
macro "%a or %b or %c":
    ".."|(\%a as lua expr\ or \%b as lua expr\ or \%c as lua expr\)
macro "%a or %b or %c or %d":
    ".."|(\%a as lua expr\ or \%b as lua expr\ or \%c as lua expr\ or \%d as lua expr\)
macro "%a mod %b": ".."|(\%a as lua expr\ mod \%b as lua expr\)
macro "- %a": ".."|-(\%a as lua expr\)
macro "not %a": ".."|not (\%a as lua expr\)

rule "%a == %b":
    lua expr "((vars.a == vars.b) or utils.equivalent(vars.a, vars.b))"
rule "%a != %b":
    lua expr "((vars.a ~= vars.b) or not utils.equivalent(vars.a, vars.b))"

macro "say %str":
    ".."|print(utils.repr(\%str as lua expr\))

# Control flow
rule "do %action":
    lua expr "vars.action(compiler, setmetatable({}, {__index=vars}))"

macro block "return %return-value":
    ".."|do return \%return-value as lua expr\ end

macro block "return":
    "do return nil end"

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

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

# Ternary operator
macro "%if_expr if %condition else %else_expr":
    ".."|(function(compiler, vars)
        |    if \%condition as lua expr\ then
        |        return \%if_expr as lua expr\
        |    else
        |        return \%else_expr as lua expr\
        |    end
        |end)(compiler, vars)

# For loop
macro block "for %varname in %iterable %body":
    let "varname" = (%varname as lua expr)
    ".."|do
        |    local old_loopval = vars[\%varname\]
        |    for i,value in ipairs(\%iterable as lua expr\) do
        |        vars[\%varname\] = value
        |        \(lua expr "vars.body.value.value") as lua block\
        |    end
        |    vars[\%varname\] = old_loopval
        |end

macro block "for all %iterable %body":
    ".."|do
        |    local old_loopval = vars.it
        |    for i,value in ipairs(\%iterable as lua expr\) do
        |        vars.it = value
        |        \(lua expr "vars.body.value.value") as lua block\
        |    end
        |    vars.it = old_loopval
        |end

# List Comprehension
# TODO: maybe make this lazy, or a lazy version?
macro "%expression for %varname in %iterable":
    ".."|(function(game, vars)
        |    local comprehension = {}
        |    for i,value in ipairs(\%iterable as lua expr\) do
        |        vars[\%varname as lua expr\] = value
        |        comprehension[i] = \%expression as lua expr\
        |    end
        |    return comprehension
        |end)(game, setmetatable({}, {__index=vars}))

macro "%expression for all %iterable":
    ".."|(function(game, vars)
        |    local comprehension = {}
        |    for i,value in ipairs(\%iterable as lua expr\) do
        |        vars.it = value
        |        comprehension[i] = \%expression as lua expr\
        |    end
        |    return comprehension
        |end)(game, setmetatable({}, {__index=vars}))

# Dict comprehension
macro "%key = %value for %varname in %iterable":
    ".."|(function(game, vars)
        |    local comprehension = {}
        |    for i,value in ipairs(\%iterable as lua expr\) do
        |        vars[\%varname as lua expr\] = value
        |        comprehension[\%key as lua expr\] = \%value as lua expr\
        |    end
        |    return comprehension
        |end)(game, setmetatable({}, {__index=vars}))

macro "%key = %value for all %iterable":
    ".."|(function(game, vars)
        |    local comprehension = {}
        |    for i,value in ipairs(\%iterable as lua expr\) do
        |        vars.it = value
        |        comprehension[\%key as lua expr\] = \%value as lua expr\
        |    end
        |    return comprehension
        |end)(game, setmetatable({}, {__index=vars}))

# Number ranges
rule "%start up to %stop":
    lua expr "utils.range(vars.start,vars.stop-1)"

rule ["%start thru %stop", "%start through %stop"]:
    lua expr "utils.range(vars.start,vars.stop)"

rule "%start down to %stop":
    lua expr "utils.range(vars.start,vars.stop+1,-1)"

rule ["%start down thru %stop", "%start down through %stop"]:
    lua expr "utils.range(vars.start,vars.stop,-1)"

rule "%start up to %stop via %step":
    lua expr "utils.range(vars.start,vars.stop-1,vars.step)"

rule ["%start thru %stop via %step", "%start through %stop via %step"]:
    lua expr "utils.range(vars.start,vars.stop,vars.step)"

rule "%start down to %stop via %step":
    lua expr "utils.range(vars.start,vars.stop+1,-vars.step)"

rule ["%start down thru %stop via %step", "%start down through %stop via %step"]:
    lua expr "utils.range(vars.start,vars.stop,-vars.step)"

# Common utility functions
rule ["random number"]: lua expr "math.random()"
rule ["sum of %items"]: lua expr "utils.sum(vars.items)"
rule ["product of %items"]: lua expr "utils.product(vars.items)"
rule ["all of %items"]: lua expr "utils.all(vars.items)"
rule ["any of %items"]: lua expr "utils.any(vars.items)"
rule ["avg of %items", "average of %items"]: lua expr "(utils.sum(vars.items)/#vars.items)"
rule ["min of %items", "smallest of %items", "lowest of %items"]:
    lua expr "utils.min(vars.items)"
rule ["max of %items", "biggest of %items", "largest of %items", "highest of %items"]:
    lua expr "utils.min(vars.items)"

rule ["min of %items with respect to %keys"]:
    lua expr "utils.min(vars.items, vars.keys)"
rule ["max of %items with respect to %keys"]:
    lua expr "utils.max(vars.items, vars.keys)"

# List/dict functions
macro [..]
    "%list 's %index", "%index st in %list", "%index nd in %list", "%index rd in %list"
    "%index th in %list", "%index in %list"
..:
    ".."|\%list as lua expr\[\%index as lua expr\]

macro block [..]
    "%list 's %index = %value", "%index st in %list = %value", "%index nd in %list = %value"
    "%index rd in %list = %value", "%index th in %list = %value", "%index in %list = %value"
..:
    ".."|\%list as lua expr\[\%index as lua expr\] = \%value as lua expr\

macro ["%item is in %list", "%list contains %item"]:
    ".."|(\%list as lua expr\[\%index as lua expr\] ~= nil)

macro ["length of %list", "size of %list", "number of %list"]:
    ".."|#(\%list as lua expr\)

rule "dict %items":
    let "dict" = []
    for "pair" in %items:
        lua block "vars.dict[vars.pair[1]] = vars.pair[2]"
    return %dict

# Permission functions
rule "restrict %fn to within %whitelist":
    lua block ".."
        |local fns = compiler:get_invocations(vars.fn)
        |local whitelist = compiler:get_invocations(vars.whitelist)
        |local whiteset = {}
        |for _,w in ipairs(whitelist) do
        |    if not compiler.defs[w] then
        |        compiler:error("Undefined function: "..tostring(w))
        |    else whiteset[w] = true
        |    end
        |end
        |for _,fn in ipairs(fns) do
        |    local fn_info = compiler.defs[fn]
        |    if fn_info == nil then
        |        compiler:error("Undefined function: "..tostring(fn))
        |    elseif not compiler:check_permission(fn) then
        |        print("You do not have permission to restrict function: "..tostring(fn))
        |    else
        |        compiler.defs[fn].whiteset = whiteset
        |    end
        |end

rule "allow %whitelist to use %fn":
    lua block ".."
        |local fns = compiler:get_invocations(vars.fn)
        |local whitelist = compiler:get_invocations(vars.whitelist)
        |for _,w in ipairs(whitelist) do
        |    if not compiler.defs[w] then
        |        compiler:error("Undefined function: "..tostring(w))
        |    end
        |end
        |for _,fn in ipairs(fns) do
        |    local fn_info = compiler.defs[fn]
        |    if fn_info == nil then
        |        compiler:error("Undefined function: "..tostring(fn))
        |    elseif fn_info.whiteset == nil then
        |        print("Function is already allowed by everyone: "..tostring(fn))
        |    elseif not compiler:check_permission(fn) then
        |        print("You do not have permission to grant permissions for function: "..tostring(fn))
        |    else
        |        for _,w in ipairs(whitelist) do
        |            fn_info.whiteset[w] = true
        |        end
        |    end
        |end

rule "forbid %blacklist to use %fn":
    lua block ".."
        |local fns = compiler:get_invocations(vars.fn)
        |local blacklist = compiler:get_invocations(vars.blacklist)
        |for _,b in ipairs(blacklist) do
        |    if not compiler.defs[b] then
        |        compiler:error("Undefined function: "..tostring(b))
        |    end
        |end
        |for _,fn in ipairs(fns) do
        |    local fn_info = compiler.defs[fn]
        |    if fn_info == nil then
        |        compiler:error("Undefined function: "..tostring(fn))
        |    elseif fn_info.whiteset == nil then
        |        print("Cannot remove items from a whitelist when there is no whitelist on function: "..tostring(fn))
        |    elseif not compiler:check_permission(fn) then
        |        print("You do not have permission to restrict function: "..tostring(fn))
        |    else
        |        for _,b in ipairs(blacklist) do fn_info.whiteset[b] = nil end
        |    end
        |end

# Error functions
rule "error!":
    lua block ".."
        |table.remove(compiler.callstack)
        |compiler:error()

rule "error %msg":
    lua block ".."
        |table.remove(compiler.callstack)
        |compiler:error(vars.msg)

macro block "test %code yields %expected":
    let "generated" = (lua expr "utils.repr(compiler:stringify_tree(vars.code.value.value), true)")
    let "expected" = (%expected as lua expr)
    if (%generated != %expected):
        say "Test failed!"
        say "Expected:"
        say %expected
        say "But got:"
        say %generated
        error!
    return ""