local utils = require("utils")
local fw = require("fastweb")
local config = require("fwutils.config")
local request = require("fastweb.request")
local response = require("fastweb.response")
local cjson = require("cjson")
local funs = require("fwutils.funs")
-- 允许的扩展名
local allowed_extensions = {
    "shtml",
    "html",
    "js"
}
local M = {
    cfg = nil,
    template_engine_bc_this_role = nil
}

-- 更新
M.update = function(conn)
    -- 查询权限表
    local select = conn:select()
    select:table("fw_template")
    select:where_i32("enable","=",1)
    local result = select:query()
    local bc = {
        public = {}
    }
    while result:next() do
        local id = result:get("id")
        local role_id = string.format("%d",result:get("role_id"))
        local key = result:get("key")
        local value = result:get("value")


        if bc[role_id] == nil then
            bc[role_id] = {}
        end
        if role_id == "0" then
            bc["public"][key] = value
        else
            bc[role_id][key] = value
        end
    end
    local code = "return " .. require("serpent").serialize(bc, {comment = false})
    utils.save_file(fw.website_dir().."/"..(fwutils_config.path.luabytecode:gsub("%.", "/")).."/template_engine_bc.lua",code)
    return true
end
-- 处理
-- @param static_content 静态内容
-- @param cfg 配置
-- @return 是否替换(TRUE则不需要继续处理，FALSE则继续处理)
M.handle = function(__cfg,functions)

    local function has_ext(ext)
        for _, v in ipairs(allowed_extensions) do
            if v == ext then
                return true
            end
        end
        return false
    end


    M.cfg = __cfg
    M.template_engine_bc_this_role = {
        template = {
            private = {},
            public = {}
        },
    }


    local ext = utils.ext(M.cfg.filepath())
    local static_content = nil
    if ext ~= nil  then
        if not has_ext(ext) then
            return false
        end
        -- 读取资源文件
        static_content = utils.read_file(fw.website_dir()..M.cfg.filepath())
        if static_content == nil or static_content == "" then
            return false
        end
    else
        -- 无需替换的扩展名
        return false
    end 
    local template_engine_bc = require(fwutils_config.path.luabytecode..".template_engine_bc")
    M.template_engine_bc_this_role["template"]["private"] = template_engine_bc[string.format("%d",M.cfg.role_id())]
    M.template_engine_bc_this_role["template"]["public"] = template_engine_bc["public"]
    

    local replaced,content = M.replace(static_content)
    if replaced then
        static_content = content
    end
    -- 执行函数
    static_content, n = static_content:gsub("%${<<<%s*(.-)%s*>>>}", function(code)
        -- 尝试编译代码（Lua 5.2+ 使用 load；Lua 5.1 可用 loadstring）
        local env = {}
        _G["engine"] = M
        local env = funs.regist(env)
        if functions ~= nil then
            env = functions.regist(env)
        end
        env["_G"] = _G
        local chunk, errmsg = load(code,nil,nil,env)
        if not chunk then
            fw.throw_string(errmsg)
        end
        -- 使用 pcall 安全执行代码块
        local status, result = pcall(chunk)
        if not status then 
            fw.throw_string(result)
        end
        -- 如果代码没有返回值，则替换为空字符串，否则转换成字符串返回
        return tostring(result)
    end)

    if n > 0 then
        replaced = true
    end
 
    if replaced then
        if  ext == "shtml" or ext == "html" then
            response.header("Content-Type","text/html")
        elseif ext == "js" then
            response.header("Content-Type","application/javascript")
        end
        response.send(static_content)
        return true
    end
    return false
end
M.replace = function (content)
    if content == nil or content == "" then
        return false 
    end
    -- 支持多级kvs替换，如 ${people.age}
    local function flatten_kvs(tbl, prefix, out)
        if tbl == nil then
            return {}
        end
        out = out or {}
        prefix = prefix or ""
        for k, v in pairs(tbl) do
            local key = prefix ~= "" and (prefix .. "." .. k) or k
            if type(v) == "table" then
                flatten_kvs(v, key, out)
            else
                out[key] = v
            end
        end
        return out
    end

    -- 先提取 content 中所有需要替换的占位符
    -- 需要正确处理 ${<<<...>>>} 块：块内部的 ${...} 需要替换，但块本身不替换
    local placeholders = {}
    
    -- 第一步：提取所有 ${<<<...>>>} 块，临时替换它们，并收集所有占位符
    local blocks = {}
    local block_index = 0
    local temp_content = content:gsub("%${<<<%s*(.-)%s*>>>}", function(block_content)
        block_index = block_index + 1
        local placeholder = "${__TEMP_BLOCK_" .. block_index .. "__}"
        -- 收集块内部的 ${...} 占位符
        for ph in string.gmatch(block_content, "%${([^}]+)}") do
            placeholders[ph] = true
        end
        blocks[block_index] = {
            placeholder = placeholder,
            content = block_content
        }
        return placeholder
    end)
    
    -- 第二步：提取外部（不在 ${<<<...>>>} 块中）的 ${...} 占位符
    for placeholder in string.gmatch(temp_content, "%${([^}]+)}") do
        -- 忽略临时占位符
        if not placeholder:match("^__TEMP_BLOCK_%d+__$") then
            placeholders[placeholder] = true
        end
    end

    -- print("PLACEHOLDERS:",cjson.encode(placeholders))
    
    -- 如果没有任何占位符，直接返回
    if next(placeholders) == nil then
        return false
    end

    -- 合并所有数据源到一个查找表中（只 flatten 一次）
    local value_map = {}
    
    -- PUBLIC
    local flat_kvs = flatten_kvs(M.template_engine_bc_this_role["template"]["public"])
    for k, v in pairs(flat_kvs) do
        value_map[k] = v
    end
    -- PRIVATE
    flat_kvs = flatten_kvs(M.template_engine_bc_this_role["template"]["private"])
    for k, v in pairs(flat_kvs) do
        value_map[k] = v
    end
    -- REQUEST
    flat_kvs = flatten_kvs(request.gets(), "request")
    for k, v in pairs(flat_kvs) do
        value_map[k] = v
    end
    -- TOKEN
    flat_kvs = flatten_kvs(M.cfg.user_data(), "token")
    for k, v in pairs(flat_kvs) do
        value_map[k] = v
    end

    -- 转义函数：将 Lua 模式特殊字符转义为字面匹配
    local function escape_pattern(str)
        return str:gsub("([%^%$%(%)%%%.%[%]%*%+%-%?])", "%%%1")
    end
    
    -- 第三步：先处理 ${<<<...>>>} 块内部的占位符
    local replaced = false
    for i, block in ipairs(blocks) do
        local block_content = block.content
        for placeholder, _ in pairs(placeholders) do
            if value_map[placeholder] ~= nil then
                local escaped_placeholder = escape_pattern(placeholder)
                local new_content, count = string.gsub(block_content, "%${" .. escaped_placeholder .. "}", tostring(value_map[placeholder]))
                if count > 0 then
                    block_content = new_content
                    replaced = true
                end
            end
        end
        blocks[i].processed_content = block_content
    end
    
    -- 第四步：替换外部的 ${...} 占位符（在临时内容中，此时块已被替换为临时占位符）
    local n = 0
    for placeholder, _ in pairs(placeholders) do
        if value_map[placeholder] ~= nil then
            local escaped_placeholder = escape_pattern(placeholder)
            temp_content, n = string.gsub(temp_content, "%${" .. escaped_placeholder .. "}", tostring(value_map[placeholder]))
            if n > 0 then
                replaced = true
            end
        end
    end
    
    -- 第五步：恢复 ${<<<...>>>} 块（使用处理后的内容）
    for i, block in ipairs(blocks) do
        local processed_block = "${<<<" .. blocks[i].processed_content .. ">>>}"
        temp_content = temp_content:gsub(block.placeholder:gsub("([%^%$%(%)%%%.%[%]%*%+%-%?])", "%%%1"), processed_block)
    end
    content = temp_content

    if replaced then
        return true, content
    end
    return false
end

-- 检查内容中是否有TOKEN变量
-- @return boolean
M.hasToken = function()
    if M.static_content == nil or M.static_content == "" then
        return false
    end
    return M.static_content:match("%${token%.") ~= nil
end

return M