local LuaHotReload = {};

local visitedSign = {}

local protection = {
    setmetatable = true,
    pairs = true,
    ipairs = true,
    next = true,
    require = true,
    _ENV = true,
}

-- function LuaHotReload.GetTableCount(srcTable)
--     local returnCount = 0;
--     if srcTable then
--         for __, __ in pairs(srcTable) do
--             returnCount = returnCount + 1;
--         end
--     end
--     return returnCount;
-- end

function LuaHotReload.UpdateFunc(newFunc, oldFunc)

    local oldUpvalueMap = {}
    for i = 1, math.huge do
        local name, value = debug.getupvalue(oldFunc, i)
        if not name then break end
        oldUpvalueMap[name] = value
    end

    for i = 1, math.huge do
        local name, value = debug.getupvalue(newFunc, i)
        if not name then break end
        local oldValue = oldUpvalueMap[name]
        if value ~= oldValue then
            if oldValue then
                if type(oldValue) ~= type(value) then
                    debug.setupvalue(newFunc, i, oldValue)
                elseif type(oldValue) == 'function' then
                    LuaHotReload.UpdateFunc(value, oldValue)
                elseif type(oldValue) == 'table' then
                    LuaHotReload.UpdateTable(value, oldValue)
                    debug.setupvalue(newFunc, i, oldValue)
                else
                    debug.setupvalue(newFunc, i, oldValue)
                end
            end
        end
    end
end

function LuaHotReload.UpdateTable(newTable, oldTable)
    if protection[newTable] or protection[oldTable] then return end
    if newTable == oldTable then return; end
    local signature = tostring(oldTable)..tostring(newTable);
    if visitedSign[signature] then return; end
    visitedSign[signature] = true;

    for name, value in pairs(newTable) do
        local oldValue = oldTable[name]
        if type(value) == type(oldValue) then
            if type(value) == 'function' then
                LuaHotReload.UpdateFunc(value, oldValue, name)
                oldTable[name] = value
            elseif type(value) == 'table' then
                LuaHotReload.UpdateTable(value, oldValue)
            end
        else
            oldTable[name] = value
        end
    end

    -- 刷新原表
    local old_meta = debug.getmetatable(oldTable);
    local new_meta = debug.getmetatable(newTable);
    if type(old_meta) == 'table' and type(new_meta) == 'table' then
        LuaHotReload.UpdateTable(new_meta, old_meta);
    end
end

function LuaHotReload.ReloadFile(chunkPath)

    -- 搭建环境
    local env = {};
    setmetatable(env, { __index = _G });
    local _ENV = env;
    visitedSign = {};

    -- loadfile 编译但是不执行
    local func = loadfile(chunkPath, 't');
    if type(func) ~= "function" then -- 加载文件出错了
        return;
    end
    setfenv(func, env); -- 设置执行环境
    local ok, newEnvTable = pcall(func);
    assert(ok, newEnvTable);
    if not ok then return; end

    local chunkTable = string.gsub(chunkPath, "/", "%.");
    local oldEnvTable = require (chunkTable);
    if (type(newEnvTable) == "table") and (type(oldEnvTable) == "table") then
        LuaHotReload.UpdateTable(newEnvTable, oldEnvTable);
    end

    -- 刷新全局环境
    for name, value in pairs(env) do
        if newEnvTable and newEnvTable.__cname == name then
            -- to do nothing
        else
            local gValue = _G[name];
            if type(gValue) ~= type(value) then
                _G[name] = value;
            elseif type(value) == 'function' then
                LuaHotReload.UpdateFunc(value, gValue);
                _G[name] = value;
            elseif type(value) == 'table' then
                LuaHotReload.UpdateTable(value, gValue);
            else -- 这个else是用来更新全局变量的
                _G[name] = value;
            end
        end
    end

    setfenv(func, _G)

    -- -- 环境回归
    -- for name, value in pairs(env) do
    --     env[name] = _G[name];
    -- end
    return 0; 
end
return LuaHotReload;