local ecs = require "ecs.core"

local function get_attrib(opt, inout)
    if opt == nil then
        return {
            exist = true,
        }
    end
    local desc = {}
    if opt == "?" then
        desc.opt = true
    else
        assert(opt == ":")
    end
    if inout == "in" then
        desc.r = true
    elseif inout == "out" or inout == "new" then
        desc.w = true
    elseif inout == "update" then
        desc.r = true
        desc.w = true
    elseif inout == "exist" then
        desc.exist = true
        assert(not desc.opt)
    else
        assert(inout == "temp")
    end
    return desc
end

local function cache_world(obj, k)
    local c = {
        typenames = {},
        id = 0,
        select = {},
        ref = {},
    }

    local function gen_ref_pat(key)
        local typenames = c.typenames
        local desc = {}
        local tc = typenames[key]
        if tc == nil then
            error("Unknown type " .. key)
        end
        local a = {
            exist = true,
            name = tc.name,
            id = tc.id,
            type = tc.type,
        }
        local n = #tc
        for i = 1, #tc do
            a[i] = tc[i]
        end
        desc[1] = a
        return desc
    end

    local function gen_select_pat(pat)
        local typenames = c.typenames
        local desc = {}
        local idx = 1
        for token in pat:gmatch "[^ ]+" do
            local key, padding = token:match "^([_%w]+)(.*)"
            assert(key, "Invalid pattern")
            local opt, inout
            if padding ~= "" then
                opt, inout = padding:match "^([:?])(%l+)$"
                assert(opt, "Invalid pattern")
            end
            local tc = typenames[key]
            if tc == nil then
                error("Unknown type " .. key)
            end
            if tc.ref and inout ~= "new" then
                local live = typenames[key .. "_live"]
                local a = {
                    exist = true,
                    name = live.name,
                    id = live.id,
                }
                desc[idx] = a
                idx = idx + 1
            end
            local a = get_attrib(opt, inout)
            a.name = tc.name
            a.id = tc.id
            a.type = tc.type
            local n = #tc
            for i = 1, #tc do
                a[i] = tc[i]
            end
            desc[idx] = a
            idx = idx + 1
        end
        return desc
    end

    local function cache_select(cache, pat)
        local pat_desc = gen_select_pat(pat)
        cache[pat] = k:_groupiter(pat_desc)
        return cache[pat]
    end

    setmetatable(c.select, {
        __mode = "kv",
        __index = cache_select,
    })

    local function cache_ref(cache, pat)
        local pat_desc = gen_ref_pat(pat)
        cache[pat] = k:_groupiter(pat_desc)
        return cache[pat]
    end

    setmetatable(c.ref, {
        __mode = "kv",
        __index = cache_ref,
    })

    obj[k] = c
    return c
end

local context = setmetatable({}, {
    __index = cache_world,
})
local typeid = {
    int = assert(ecs._TYPEINT),
    float = assert(ecs._TYPEFLOAT),
    bool = assert(ecs._TYPEBOOL),
    int64 = assert(ecs._TYPEINT64),
    dword = assert(ecs._TYPEDWORD),
    word = assert(ecs._TYPEWORD),
    byte = assert(ecs._TYPEBYTE),
    double = assert(ecs._TYPEDOUBLE),
    userdata = assert(ecs._TYPEUSERDATA),
}
local typesize = {
    [typeid.int] = 4,
    [typeid.float] = 4,
    [typeid.bool] = 1,
    [typeid.int64] = 8,
    [typeid.dword] = 4,
    [typeid.word] = 2,
    [typeid.byte] = 1,
    [typeid.double] = 8,
    [typeid.userdata] = 8,
}

local M = ecs._METHODS

do -- newtype
    local function parse(s)
        -- s is "name:typename"
        local name, typename = s:match "^([%w_]+):(%w+)$"
        local typeid = assert(typeid[typename])
        return {typeid, name}
    end

    local function align(c, field)
        local t = field[1]
        local tsize = typesize[t]
        local offset = ((c.size + tsize - 1) & ~(tsize - 1))
        c.size = offset + tsize
        field[3] = offset
        return field
    end

    local function align_struct(c, t)
        if t then
            local s = typesize[t] - 1
            c.size = ((c.size + s) & ~s)
        end
    end

    function M:register(typeclass)
        local name = assert(typeclass.name)
        local ctx = context[self]
        local typenames = ctx.typenames
        local id = ctx.id + 1
        assert(typenames[name] == nil and id <= ecs._MAXTYPE)
        ctx.id = id
        local c = {
            id = id,
            name = name,
            size = 0,
        }
        for i, v in ipairs(typeclass) do
            c[i] = align(c, parse(v))
        end
        local ttype = typeclass.type
        if ttype == "lua" then
            assert(c.size == 0)
            c.size = ecs._LUAOBJECT
            c.islua = true
        elseif c.size > 0 then
            align_struct(c, typeclass[1][1])
        else
            -- size == 0, one value
            if ttype then
                local t = assert(typeid[typeclass.type])
                c.type = t
                c.size = typesize[t]
                c[1] = {t, "v", 0}
            else
                c.tag = true
            end
        end
        typenames[name] = c
        self:_newtype(id, c.size)
        if typeclass.ref then
            c.ref = true
            self:register{
                name = name .. "_live",
            }
            self:register{
                name = name .. "_dead",
            }
        end
    end
end

local function dump(obj)
    for e, v in pairs(obj) do
        if type(v) == "table" then
            for k, v in pairs(v) do
                print(e, k, v)
            end
        else
            print(e, v)
        end
    end
end

function M:new(obj)
    --	dump(obj)
    local eid = self:_newentity()
    local typenames = context[self].typenames
    for k, v in pairs(obj) do
        local tc = typenames[k]
        if not tc then
            error("Invalid key : " .. k)
        end
        local id = self:_addcomponent(eid, tc.id)
        self:object(k, id, v)
    end
end

local ref_key = setmetatable({}, {
    __index = function(cache, key)
        local select_key = string.format("%s_dead:out %s_live?out %s:new", key, key, key)
        cache[key] = select_key
        return select_key
    end,
})

function M:ref(name, obj)
    local ctx = context[self]
    local typenames = ctx.typenames
    local tc = assert(typenames[name])
    local live = name .. "_live"
    local dead = name .. "_dead"
    obj = obj or tc.tag
    for v in self:select(dead) do
        v[dead] = false
        v[live] = true
        v[name] = obj
        return self:sync(ref_key[name], v)
    end
    local eid = self:_newentity()
    local id = self:_addcomponent(eid, tc.id)
    self:object(name, id, obj)
    self:object(live, self:_addcomponent(eid, typenames[live].id), true)
    return id
end

function M:release(name, refid)
    local id = assert(context[self].typenames[name].id)
    self:_release(id, refid)
end

function M:context(t)
    local typenames = context[self].typenames
    local id = {}
    for i, name in ipairs(t) do
        local tc = typenames[name]
        if not tc then
            error("Invalid component name " .. name)
        end
        id[i] = tc.id
    end
    return self:_context(id)
end

function M:select(pat)
    return context[self].select[pat]()
end

function M:sync(pat, iter)
    local p = context[self].select[pat]
    return self:_sync(p, iter)
end

function M:clear(name)
    local id = assert(context[self].typenames[name].id)
    self:_clear(id)
end

function M:sort(sorted, name)
    local ctx = context[self]
    local typenames = ctx.typenames
    local t = assert(typenames[name])
    assert(t.type == typeid.int or (#t == 1 and t[1][1] == typeid.float))
    local stype = typenames[sorted]
    if stype == nil then
        local id = ctx.id + 1
        assert(id <= ecs._MAXTYPE)
        ctx.id = id
        stype = {
            id = id,
            name = sorted,
            size = ecs._ORDERKEY,
            tag = true,
        }
        self:_newtype(id, stype.size)
        typenames[sorted] = stype
    else
        assert(stype.size == ecs._ORDERKEY)
    end
    self:_sortkey(stype.id, t.id)
end

do
    local _object = M._object
    function M:object(name, refid, v)
        local pat = context[self].ref[name]
        return _object(pat, v, refid)
    end

    function M:singleton(name, v)
        local pat = context[self].ref[name]
        return _object(pat, v)
    end
end

function ecs.world()
    local w = ecs._world()
    context[w].typenames.REMOVED = {
        name = "REMOVED",
        id = ecs._REMOVED,
        size = 0,
        tag = true,
    }
    return w
end

return ecs