-- binser.lua

--[[
Copyright (c) 2016-2019 Calvin Rose

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
]]

local assert = assert
local error = error
local select = select
local pairs = pairs
local getmetatable = getmetatable
local setmetatable = setmetatable
local type = type
local loadstring = loadstring or load
local concat = table.concat
local char = string.char
local byte = string.byte
local format = string.format
local sub = string.sub
local dump = string.dump
local floor = math.floor
local frexp = math.frexp
local unpack = unpack or table.unpack

-- Lua 5.3 frexp polyfill
-- From https://github.com/excessive/cpml/blob/master/modules/utils.lua
if not frexp then
    local log, abs, floor = math.log, math.abs, math.floor
    local log2 = log(2)
    frexp = function(x)
        if x == 0 then return 0, 0 end
        local e = floor(log(abs(x)) / log2 + 1)
        return x / 2 ^ e, e
    end
end

local function pack(...)
    return {...}, select("#", ...)
end

local function not_array_index(x, len)
    return type(x) ~= "number" or x < 1 or x > len or x ~= floor(x)
end

local function type_check(x, tp, name)
    assert(type(x) == tp,
        format("Expected parameter %q to be of type %q.", name, tp))
end

local bigIntSupport = false
local isInteger
if math.type then -- Detect Lua 5.3
    local mtype = math.type
    bigIntSupport = loadstring[[
    local char = string.char
    return function(n)
        local nn = n < 0 and -(n + 1) or n
        local b1 = nn // 0x100000000000000
        local b2 = nn // 0x1000000000000 % 0x100
        local b3 = nn // 0x10000000000 % 0x100
        local b4 = nn // 0x100000000 % 0x100
        local b5 = nn // 0x1000000 % 0x100
        local b6 = nn // 0x10000 % 0x100
        local b7 = nn // 0x100 % 0x100
        local b8 = nn % 0x100
        if n < 0 then
            b1, b2, b3, b4 = 0xFF - b1, 0xFF - b2, 0xFF - b3, 0xFF - b4
            b5, b6, b7, b8 = 0xFF - b5, 0xFF - b6, 0xFF - b7, 0xFF - b8
        end
        return char(212, b1, b2, b3, b4, b5, b6, b7, b8)
    end]]()
    isInteger = function(x)
        return mtype(x) == 'integer'
    end
else
    isInteger = function(x)
        return floor(x) == x
    end
end

-- Copyright (C) 2012-2015 Francois Perrad.
-- number serialization code modified from https://github.com/fperrad/lua-MessagePack
-- Encode a number as a big-endian ieee-754 double, big-endian signed 64 bit integer, or a small integer
local function number_to_str(n)
    if isInteger(n) then -- int
        if n <= 100 and n >= -27 then -- 1 byte, 7 bits of data
            return char(n + 27)
        elseif n <= 8191 and n >= -8192 then -- 2 bytes, 14 bits of data
            n = n + 8192
            return char(128 + (floor(n / 0x100) % 0x100), n % 0x100)
        elseif bigIntSupport then
            return bigIntSupport(n)
        end
    end
    local sign = 0
    if n < 0.0 then
        sign = 0x80
        n = -n
    end
    local m, e = frexp(n) -- mantissa, exponent
    if m ~= m then
        return char(203, 0xFF, 0xF8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00)
    elseif m == 1/0 then
        if sign == 0 then
            return char(203, 0x7F, 0xF0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00)
        else
            return char(203, 0xFF, 0xF0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00)
        end
    end
    e = e + 0x3FE
    if e < 1 then -- denormalized numbers
        m = m * 2 ^ (52 + e)
        e = 0
    else
        m = (m * 2 - 1) * 2 ^ 52
    end
    return char(203,
                sign + floor(e / 0x10),
                (e % 0x10) * 0x10 + floor(m / 0x1000000000000),
                floor(m / 0x10000000000) % 0x100,
                floor(m / 0x100000000) % 0x100,
                floor(m / 0x1000000) % 0x100,
                floor(m / 0x10000) % 0x100,
                floor(m / 0x100) % 0x100,
                m % 0x100)
end

-- Copyright (C) 2012-2015 Francois Perrad.
-- number deserialization code also modified from https://github.com/fperrad/lua-MessagePack
local function number_from_str(str, index)
    local b = byte(str, index)
    if not b then error("Expected more bytes of input.") end
    if b < 128 then
        return b - 27, index + 1
    elseif b < 192 then
        local b2 = byte(str, index + 1)
        if not b2 then error("Expected more bytes of input.") end
        return b2 + 0x100 * (b - 128) - 8192, index + 2
    end
    local b1, b2, b3, b4, b5, b6, b7, b8 = byte(str, index + 1, index + 8)
    if (not b1) or (not b2) or (not b3) or (not b4) or
        (not b5) or (not b6) or (not b7) or (not b8) then
        error("Expected more bytes of input.")
    end
    if b == 212 then
        local flip = b1 >= 128
        if flip then -- negative
            b1, b2, b3, b4 = 0xFF - b1, 0xFF - b2, 0xFF - b3, 0xFF - b4
            b5, b6, b7, b8 = 0xFF - b5, 0xFF - b6, 0xFF - b7, 0xFF - b8
        end
        local n = ((((((b1 * 0x100 + b2) * 0x100 + b3) * 0x100 + b4) *
            0x100 + b5) * 0x100 + b6) * 0x100 + b7) * 0x100 + b8
        if flip then
            return (-n) - 1, index + 9
        else
            return n, index + 9
        end
    end
    if b ~= 203 then
        error("Expected number")
    end
    local sign = b1 > 0x7F and -1 or 1
    local e = (b1 % 0x80) * 0x10 + floor(b2 / 0x10)
    local m = ((((((b2 % 0x10) * 0x100 + b3) * 0x100 + b4) * 0x100 + b5) * 0x100 + b6) * 0x100 + b7) * 0x100 + b8
    local n
    if e == 0 then
        if m == 0 then
            n = sign * 0.0
        else
            n = sign * (m / 2 ^ 52) * 2 ^ -1022
        end
    elseif e == 0x7FF then
        if m == 0 then
            n = sign * (1/0)
        else
            n = 0.0/0.0
        end
    else
        n = sign * (1.0 + m / 2 ^ 52) * 2 ^ (e - 0x3FF)
    end
    return n, index + 9
end


local function newbinser()

    -- unique table key for getting next value
    local NEXT = {}
    local CTORSTACK = {}

    -- NIL = 202
    -- FLOAT = 203
    -- TRUE = 204
    -- FALSE = 205
    -- STRING = 206
    -- TABLE = 207
    -- REFERENCE = 208
    -- CONSTRUCTOR = 209
    -- FUNCTION = 210
    -- RESOURCE = 211
    -- INT64 = 212
    -- TABLE WITH META = 213

    local mts = {}
    local ids = {}
    local serializers = {}
    local deserializers = {}
    local resources = {}
    local resources_by_name = {}
    local types = {}

    types["nil"] = function(x, visited, accum)
        accum[#accum + 1] = "\202"
    end

    function types.number(x, visited, accum)
        accum[#accum + 1] = number_to_str(x)
    end

    function types.boolean(x, visited, accum)
        accum[#accum + 1] = x and "\204" or "\205"
    end

    function types.string(x, visited, accum)
        local alen = #accum
        if visited[x] then
            accum[alen + 1] = "\208"
            accum[alen + 2] = number_to_str(visited[x])
        else
            visited[x] = visited[NEXT]
            visited[NEXT] =  visited[NEXT] + 1
            accum[alen + 1] = "\206"
            accum[alen + 2] = number_to_str(#x)
            accum[alen + 3] = x
        end
    end

    local function check_custom_type(x, visited, accum)
        local res = resources[x]
        if res then
            accum[#accum + 1] = "\211"
            types[type(res)](res, visited, accum)
            return true
        end
        local mt = getmetatable(x)
        local id = mt and ids[mt]
        if id then
            local constructing = visited[CTORSTACK]
            if constructing[x] then
                error("Infinite loop in constructor.")
            end
            constructing[x] = true
            accum[#accum + 1] = "\209"
            types[type(id)](id, visited, accum)
            local args, len = pack(serializers[id](x))
            accum[#accum + 1] = number_to_str(len)
            for i = 1, len do
                local arg = args[i]
                types[type(arg)](arg, visited, accum)
            end
            visited[x] = visited[NEXT]
            visited[NEXT] = visited[NEXT] + 1
            -- We finished constructing
            constructing[x] = nil
            return true
        end
    end

    function types.userdata(x, visited, accum)
        if visited[x] then
            accum[#accum + 1] = "\208"
            accum[#accum + 1] = number_to_str(visited[x])
        else
            if check_custom_type(x, visited, accum) then return end
            error("Cannot serialize this userdata.")
        end
    end

    function types.table(x, visited, accum)
        if visited[x] then
            accum[#accum + 1] = "\208"
            accum[#accum + 1] = number_to_str(visited[x])
        else
            if check_custom_type(x, visited, accum) then return end
            visited[x] = visited[NEXT]
            visited[NEXT] =  visited[NEXT] + 1
            local xlen = #x
            local mt = getmetatable(x)
            if mt then
                accum[#accum + 1] = "\213"
                types.table(mt, visited, accum)
            else
                accum[#accum + 1] = "\207"
            end
            accum[#accum + 1] = number_to_str(xlen)
            for i = 1, xlen do
                local v = x[i]
                types[type(v)](v, visited, accum)
            end
            local key_count = 0
            for k in pairs(x) do
                if not_array_index(k, xlen) then
                    key_count = key_count + 1
                end
            end
            accum[#accum + 1] = number_to_str(key_count)
            for k, v in pairs(x) do
                if not_array_index(k, xlen) then
                    types[type(k)](k, visited, accum)
                    types[type(v)](v, visited, accum)
                end
            end
        end
    end

    types["function"] = function(x, visited, accum)
        if visited[x] then
            accum[#accum + 1] = "\208"
            accum[#accum + 1] = number_to_str(visited[x])
        else
            if check_custom_type(x, visited, accum) then return end
            visited[x] = visited[NEXT]
            visited[NEXT] =  visited[NEXT] + 1
            local str = dump(x)
            accum[#accum + 1] = "\210"
            accum[#accum + 1] = number_to_str(#str)
            accum[#accum + 1] = str
        end
    end

    types.cdata = function(x, visited, accum)
        if visited[x] then
            accum[#accum + 1] = "\208"
            accum[#accum + 1] = number_to_str(visited[x])
        else
            if check_custom_type(x, visited, #accum) then return end
            error("Cannot serialize this cdata.")
        end
    end

    types.thread = function() error("Cannot serialize threads.") end

    local function deserialize_value(str, index, visited)
        local t = byte(str, index)
        if not t then return nil, index end
        if t < 128 then
            return t - 27, index + 1
        elseif t < 192 then
            local b2 = byte(str, index + 1)
            if not b2 then error("Expected more bytes of input.") end
            return b2 + 0x100 * (t - 128) - 8192, index + 2
        elseif t == 202 then
            return nil, index + 1
        elseif t == 203 or t == 212 then
            return number_from_str(str, index)
        elseif t == 204 then
            return true, index + 1
        elseif t == 205 then
            return false, index + 1
        elseif t == 206 then
            local length, dataindex = number_from_str(str, index + 1)
            local nextindex = dataindex + length
            if not (length >= 0) then error("Bad string length") end
            if #str < nextindex - 1 then error("Expected more bytes of string") end
            local substr = sub(str, dataindex, nextindex - 1)
            visited[#visited + 1] = substr
            return substr, nextindex
        elseif t == 207 or t == 213 then
            local mt, count, nextindex
            local ret = {}
            visited[#visited + 1] = ret
            nextindex = index + 1
            if t == 213 then
                mt, nextindex = deserialize_value(str, nextindex, visited)
                if type(mt) ~= "table" then error("Expected table metatable") end
            end
            count, nextindex = number_from_str(str, nextindex)
            for i = 1, count do
                local oldindex = nextindex
                ret[i], nextindex = deserialize_value(str, nextindex, visited)
                if nextindex == oldindex then error("Expected more bytes of input.") end
            end
            count, nextindex = number_from_str(str, nextindex)
            for i = 1, count do
                local k, v
                local oldindex = nextindex
                k, nextindex = deserialize_value(str, nextindex, visited)
                if nextindex == oldindex then error("Expected more bytes of input.") end
                oldindex = nextindex
                v, nextindex = deserialize_value(str, nextindex, visited)
                if nextindex == oldindex then error("Expected more bytes of input.") end
                if k == nil then error("Can't have nil table keys") end
                ret[k] = v
            end
            if mt then setmetatable(ret, mt) end
            return ret, nextindex
        elseif t == 208 then
            local ref, nextindex = number_from_str(str, index + 1)
            return visited[ref], nextindex
        elseif t == 209 then
            local count
            local name, nextindex = deserialize_value(str, index + 1, visited)
            count, nextindex = number_from_str(str, nextindex)
            local args = {}
            for i = 1, count do
                local oldindex = nextindex
                args[i], nextindex = deserialize_value(str, nextindex, visited)
                if nextindex == oldindex then error("Expected more bytes of input.") end
            end
            if not name or not deserializers[name] then
                error(("Cannot deserialize class '%s'"):format(tostring(name)))
            end
            local ret = deserializers[name](unpack(args))
            visited[#visited + 1] = ret
            return ret, nextindex
        elseif t == 210 then
            local length, dataindex = number_from_str(str, index + 1)
            local nextindex = dataindex + length
            if not (length >= 0) then error("Bad string length") end
            if #str < nextindex - 1 then error("Expected more bytes of string") end
            -- XXX: tack: removed non-safe deserialization of functions.
            -- local ret = loadstring(sub(str, dataindex, nextindex - 1))
            local ret = function() error("deserializing functions not supported") end
            visited[#visited + 1] = ret
            return ret, nextindex
        elseif t == 211 then
            local resname, nextindex = deserialize_value(str, index + 1, visited)
            if resname == nil then error("Got nil resource name") end
            local res = resources_by_name[resname]
            if res == nil then
                error(("No resources found for name '%s'"):format(tostring(resname)))
            end
            return res, nextindex
        else
            error("Could not deserialize type byte " .. t .. ".")
        end
    end

    local function serialize(...)
        local visited = {[NEXT] = 1, [CTORSTACK] = {}}
        local accum = {}
        for i = 1, select("#", ...) do
            local x = select(i, ...)
            types[type(x)](x, visited, accum)
        end
        return concat(accum)
    end

    local function make_file_writer(file)
        return setmetatable({}, {
            __newindex = function(_, _, v)
                file:write(v)
            end
        })
    end

    local function serialize_to_file(path, mode, ...)
        local file, err = io.open(path, mode)
        assert(file, err)
        local visited = {[NEXT] = 1, [CTORSTACK] = {}}
        local accum = make_file_writer(file)
        for i = 1, select("#", ...) do
            local x = select(i, ...)
            types[type(x)](x, visited, accum)
        end
        -- flush the writer
        file:flush()
        file:close()
    end

    local function writeFile(path, ...)
        return serialize_to_file(path, "wb", ...)
    end

    local function appendFile(path, ...)
        return serialize_to_file(path, "ab", ...)
    end

    local function deserialize(str, index)
        assert(type(str) == "string", "Expected string to deserialize.")
        local vals = {}
        index = index or 1
        local visited = {}
        local len = 0
        local val
        while true do
            local nextindex
            val, nextindex = deserialize_value(str, index, visited)
            if nextindex > index then
                len = len + 1
                vals[len] = val
                index = nextindex
            else
                break
            end
        end
        return vals, len
    end

    local function deserializeN(str, n, index)
        assert(type(str) == "string", "Expected string to deserialize.")
        n = n or 1
        assert(type(n) == "number", "Expected a number for parameter n.")
        assert(n > 0 and floor(n) == n, "N must be a poitive integer.")
        local vals = {}
        index = index or 1
        local visited = {}
        local len = 0
        local val
        while len < n do
            local nextindex
            val, nextindex = deserialize_value(str, index, visited)
            if nextindex > index then
                len = len + 1
                vals[len] = val
                index = nextindex
            else
                break
            end
        end
        vals[len + 1] = index
        return unpack(vals, 1, n + 1)
    end

    local function readFile(path)
        local file, err = io.open(path, "rb")
        assert(file, err)
        local str = file:read("*all")
        file:close()
        return deserialize(str)
    end

    -- Resources

    local function registerResource(resource, name)
        type_check(name, "string", "name")
        assert(not resources[resource],
            "Resource already registered.")
        assert(not resources_by_name[name],
            format("Resource %q already exists.", name))
        resources_by_name[name] = resource
        resources[resource] = name
        return resource
    end

    local function unregisterResource(name)
        type_check(name, "string", "name")
        assert(resources_by_name[name], format("Resource %q does not exist.", name))
        local resource = resources_by_name[name]
        resources_by_name[name] = nil
        resources[resource] = nil
        return resource
    end

    -- Templating

    local function normalize_template(template)
        local ret = {}
        for i = 1, #template do
            ret[i] = template[i]
        end
        local non_array_part = {}
        -- The non-array part of the template (nested templates) have to be deterministic, so they are sorted.
        -- This means that inherently non deterministicly sortable keys (tables, functions) should NOT be used
        -- in templates. Looking for way around this.
        for k in pairs(template) do
            if not_array_index(k, #template) then
                non_array_part[#non_array_part + 1] = k
            end
        end
        table.sort(non_array_part)
        for i = 1, #non_array_part do
            local name = non_array_part[i]
            ret[#ret + 1] = {name, normalize_template(template[name])}
        end
        return ret
    end

    local function templatepart_serialize(part, argaccum, x, len)
        local extras = {}
        local extracount = 0
        for k, v in pairs(x) do
            extras[k] = v
            extracount = extracount + 1
        end
        for i = 1, #part do
            local name
            if type(part[i]) == "table" then
                name = part[i][1]
                len = templatepart_serialize(part[i][2], argaccum, x[name], len)
            else
                name = part[i]
                len = len + 1
                argaccum[len] = x[part[i]]
            end
            if extras[name] ~= nil then
                extracount = extracount - 1
                extras[name] = nil
            end
        end
        if extracount > 0 then
            argaccum[len + 1] = extras
        else
            argaccum[len + 1] = nil
        end
        return len + 1
    end

    local function templatepart_deserialize(ret, part, values, vindex)
        for i = 1, #part do
            local name = part[i]
            if type(name) == "table" then
                local newret = {}
                ret[name[1]] = newret
                vindex = templatepart_deserialize(newret, name[2], values, vindex)
            else
                ret[name] = values[vindex]
                vindex = vindex + 1
            end
        end
        local extras = values[vindex]
        if extras then
            for k, v in pairs(extras) do
                ret[k] = v
            end
        end
        return vindex + 1
    end

    local function template_serializer_and_deserializer(metatable, template)
        return function(x)
            local argaccum = {}
            local len = templatepart_serialize(template, argaccum, x, 0)
            return unpack(argaccum, 1, len)
        end, function(...)
            local ret = {}
            local args = {...}
            templatepart_deserialize(ret, template, args, 1)
            return setmetatable(ret, metatable)
        end
    end

    -- Used to serialize classes withh custom serializers and deserializers.
    -- If no _serialize or _deserialize (or no _template) value is found in the
    -- metatable, then the metatable is registered as a resources.
    local function register(metatable, name, serialize, deserialize)
        if type(metatable) == "table" then
            name = name or metatable.name
            serialize = serialize or metatable._serialize
            deserialize = deserialize or metatable._deserialize
            if (not serialize) or (not deserialize) then
                if metatable._template then
                    -- Register as template
                    local t = normalize_template(metatable._template)
                    serialize, deserialize = template_serializer_and_deserializer(metatable, t)
                else
                    -- Register the metatable as a resource. This is semantically
                    -- similar and more flexible (handles cycles).
                    registerResource(metatable, name)
                    return
                end
            end
        elseif type(metatable) == "string" then
            name = name or metatable
        end
        type_check(name, "string", "name")
        type_check(serialize, "function", "serialize")
        type_check(deserialize, "function", "deserialize")
        assert((not ids[metatable]) and (not resources[metatable]),
            "Metatable already registered.")
        assert((not mts[name]) and (not resources_by_name[name]),
            ("Name %q already registered."):format(name))
        mts[name] = metatable
        ids[metatable] = name
        serializers[name] = serialize
        deserializers[name] = deserialize
        return metatable
    end

    local function unregister(item)
        local name, metatable
        if type(item) == "string" then -- assume name
            name, metatable = item, mts[item]
        else -- assume metatable
            name, metatable = ids[item], item
        end
        type_check(name, "string", "name")
        mts[name] = nil
        if (metatable) then
            resources[metatable] = nil
            ids[metatable] = nil
        end
        serializers[name] = nil
        deserializers[name] = nil
        resources_by_name[name] = nil;
        return metatable
    end

    local function registerClass(class, name)
        name = name or class.name
        if class.__instanceDict then -- middleclass
            register(class.__instanceDict, name)
        else -- assume 30log or similar library
            register(class, name)
        end
        return class
    end

    return {
        VERSION = "0.0-8",
        -- aliases
        s = serialize,
        d = deserialize,
        dn = deserializeN,
        r = readFile,
        w = writeFile,
        a = appendFile,

        serialize = serialize,
        deserialize = deserialize,
        deserializeN = deserializeN,
        readFile = readFile,
        writeFile = writeFile,
        appendFile = appendFile,
        register = register,
        unregister = unregister,
        registerResource = registerResource,
        unregisterResource = unregisterResource,
        registerClass = registerClass,

        newbinser = newbinser
    }
end

return newbinser()
