server {
    listen 8080;

    # 精确匹配（优先级最高）
    location = /api/health {
        content_by_lua_block { ngx.say("OK") }
    }

    # 前缀匹配（停止搜索正则）
    location ^~ /api/v1/ {
        proxy_pass http://v1_backend;
    }

    # 正则匹配（按顺序匹配，第一个匹配的生效）
    location ~ ^/api/users/(\d+)$ {
        set $user_id $1;
        proxy_pass http://user_backend;
    }

    # 正则匹配（忽略大小写）
    location ~* \.(jpg|png|gif)$ {
        root /var/www/static;
    }

    # 普通前缀匹配
    location /api/ {
        proxy_pass http://default_backend;
    }

    # 默认匹配
    location / {
        content_by_lua_block { ngx.say("Welcome") }
    }
}

-- /usr/local/openresty/lua/router.lua
local _M = {}
local cjson = require "cjson"

-- 路由表
local routes = {
    -- 精确匹配
    exact = {
        ["/api/health"]   = {upstream = "health_service",  strip_prefix = false},
        ["/api/version"]  = {upstream = "version_service", strip_prefix = false},
    },

    -- 前缀匹配
    prefix = {
        ["/api/users"]    = {upstream = "user_service",  strip_prefix = false},
        ["/api/orders"]   = {upstream = "order_service", strip_prefix = false},
        ["/api/products"] = {upstream = "product_service", strip_prefix = false},
        ["/api/payments"] = {upstream = "payment_service", strip_prefix = false},
    },

    -- 正则匹配
    pattern = {
        {pattern = "^/api/v(%d+)/(.+)$",  upstream = "versioned", strip_prefix = false},
        {pattern = "^/user/(%d+)/profile$", upstream = "user_service", strip_prefix = false},
    },
}

-- 匹配函数
function _M.match(uri)
    -- 1. 精确匹配（O(1) 哈希查找）
    local route = routes.exact[uri]
    if route then
        return route, uri
    end

    -- 2. 前缀匹配
    for prefix, r in pairs(routes.prefix) do
        if uri:sub(1, #prefix) == prefix then
            local remainder = uri:sub(#prefix + 1)
            return r, remainder
        end
    end

    -- 3. 正则匹配
    for _, r in ipairs(routes.pattern) do
        local captures = {uri:match(r.pattern)}
        if #captures > 0 then
            return r, captures
        end
    end

    return nil, nil
end

return _M

server {
    listen 8080;

    # 定义后端上游
    upstream user_service {
        server 127.0.0.1:8081;
        server 127.0.0.1:8082;
    }

    upstream order_service {
        server 127.0.0.1:8083;
    }

    upstream product_service {
        server 127.0.0.1:8084;
    }

    location /api/ {
        content_by_lua_file /usr/local/openresty/lua/route_handler.lua;
    }
}

-- /usr/local/openresty/lua/route_handler.lua
local router = require "router"
local http = require "resty.http"
local cjson = require "cjson"

local uri = ngx.var.uri
local route, remainder = router.match(uri)

if not route then
    ngx.status = 404
    ngx.say(cjson.encode({
        error = "Not Found",
        message = "No route matched: " .. uri,
        available_routes = {"/api/users", "/api/orders", "/api/products"},
    }))
    return
end

-- 获取上游地址
local upstream = route.upstream

-- 转发请求
local httpc = http.new()
httpc:set_timeout(5000)

local upstream_url = "http://" .. upstream .. uri

local res, err = httpc:request_uri(upstream_url, {
    method = ngx.req.get_method(),
    body = ngx.req.get_body_data(),
    headers = ngx.req.get_headers(),
})

if not res then
    ngx.status = 502
    ngx.say(cjson.encode({error = "Bad Gateway", message = err}))
    return
end

ngx.status = res.status
ngx.say(res.body)

-- /usr/local/openresty/lua/trie_router.lua
local _M = {}

function _M.new()
    return {
        root = {children = {}, handler = nil, params = {}}
    }
end

-- 注册路由
function _M:add(method, path, handler)
    local node = self.root
    local segments = {}

    for segment in path:gmatch("[^/]+") do
        -- 参数段 :param
        if segment:sub(1, 1) == ":" then
            table.insert(segments, {name = segment:sub(2), is_param = true})
            segment = ":"
        else
            table.insert(segments, {name = segment, is_param = false})
        end

        if not node.children[segment] then
            node.children[segment] = {children = {}, handler = nil, params = {}}
        end
        node = node.children[segment]
    end

    node.handler = handler
    node.segments = segments
end

-- 匹配路由
function _M:match(method, path)
    local node = self.root
    local params = {}
    local segments = {}

    for segment in path:gmatch("[^/]+") do
        table.insert(segments, segment)
    end

    for i, seg in ipairs(segments) do
        -- 先尝试精确匹配
        if node.children[seg] then
            node = node.children[seg]
        -- 再尝试参数匹配
        elseif node.children[":"] then
            node = node.children[":"]
            if node.segments and node.segments[i] then
                params[node.segments[i].name] = seg
            end
        else
            return nil
        end
    end

    if node.handler then
        return node.handler, params
    end
    return nil
end

return _M

-- /usr/local/openresty/lua/route_handler_trie.lua
local trie = require "trie_router"

local router = trie.new()

-- 注册路由
router:add("GET", "/api/users", function(params)
    ngx.say("List users")
end)

router:add("GET", "/api/users/:id", function(params)
    ngx.say("Get user: " .. params.id)
end)

router:add("GET", "/api/users/:id/orders", function(params)
    ngx.say("Get orders for user: " .. params.id)
end)

router:add("POST", "/api/users", function(params)
    ngx.req.read_body()
    ngx.say("Create user: " .. (ngx.req.get_body_data() or ""))
end)

-- 执行路由匹配
local method = ngx.req.get_method()
local uri = ngx.var.uri

local handler, params = router:match(method, uri)
if handler then
    handler(params)
else
    ngx.status = 404
    ngx.say('{"error":"Not Found"}')
end

-- /usr/local/openresty/lua/version_router.lua
local _M = {}

local upstreams = {
    v1 = "http://api-v1-service:8080",
    v2 = "http://api-v2-service:8080",
    v3 = "http://api-v3-service:8080",
}

-- 默认版本
local default_version = "v2"

-- 版本提取
function _M.extract_version()
    local uri = ngx.var.uri

    -- 方式 1：路径版本 /api/v1/users
    local version = uri:match("^/api/(v%d+)/")
    if version then
        return version, uri:gsub("^/api/v%d+", "")
    end

    -- 方式 2：查询参数 ?api_version=v1
    local args = ngx.req.get_uri_args()
    version = args.api_version or args.v
    if version and version:match("^v%d+$") then
        return version, uri
    end

    -- 方式 3：请求头 X-API-Version
    version = ngx.var.http_x_api_version
    if version and version:match("^v%d+$") then
        return version, uri
    end

    -- 方式 4：Accept 头版本
    local accept = ngx.var.http_accept or ""
    version = accept:match("application/vnd%.api%.(v%d+)%+json")
    if version then
        return version, uri
    end

    return default_version, uri
end

-- 获取上游地址
function _M.get_upstream(version)
    return upstreams[version] or upstreams[default_version]
end

return _M

server {
    listen 8080;

    location /api/ {
        set $api_version "";
        set $backend_uri "";

        access_by_lua_block {
            local vr = require "version_router"
            local version, stripped_uri = vr.extract_version()

            ngx.var.api_version = version
            ngx.var.backend_uri = stripped_uri

            -- 记录版本信息
            ngx.log(ngx.INFO, "API version: ", version, ", URI: ", stripped_uri)
        }

        proxy_pass http://api-$api_version-service:8080$backend_uri;
        proxy_set_header X-API-Version $api_version;
        proxy_set_header X-Original-URI $request_uri;
    }
}

-- /usr/local/openresty/lua/canary.lua
local _M = {}

-- 灰度配置（可从配置中心动态加载）
local canary_config = {
    enabled = true,
    strategy = "user_id",   -- 灰度策略
    percentage = 10,        -- 10% 流量到灰度版本
    whitelist = {           -- 强制灰度的用户
        "user_001", "user_002", "user_003",
    },
    -- 基于 header 的灰度
    header_name = "X-Canary",
    header_value = "true",
}

-- 一致性哈希（确保同一用户始终路由到同一版本）
local function stable_hash(key)
    local hash = 5381
    for i = 1, #key do
        hash = ((hash * 33) + string.byte(key, i)) % 2147483647
    end
    return hash
end

function _M.should_canary()
    if not canary_config.enabled then
        return false
    end

    -- 策略 1：Header 灰度
    local canary_header = ngx.req.get_headers()[canary_config.header_name]
    if canary_header == canary_config.header_value then
        return true
    end

    -- 策略 2：白名单用户
    local user_id = ngx.var.http_x_user_id or ngx.var.cookie_user_id
    if user_id then
        for _, uid in ipairs(canary_config.whitelist) do
            if uid == user_id then
                return true
            end
        end
    end

    -- 策略 3：百分比灰度（基于用户 ID 的一致性哈希）
    if user_id then
        local hash = stable_hash(user_id)
        if (hash % 100) < canary_config.percentage then
            return true
        end
    else
        -- 无用户 ID 时使用 IP
        local client_ip = ngx.var.remote_addr
        local hash = stable_hash(client_ip)
        if (hash % 100) < canary_config.percentage then
            return true
        end
    end

    return false
end

function _M.get_upstream()
    if _M.should_canary() then
        return "canary_backend"
    end
    return "stable_backend"
end

return _M

http {
    upstream stable_backend {
        server 10.0.1.1:8080;
        server 10.0.1.2:8080;
    }

    upstream canary_backend {
        server 10.0.2.1:8080;  -- 新版本
    }

    server {
        listen 8080;

        location /api/ {
            set $target_backend "";

            access_by_lua_block {
                local canary = require "canary"
                ngx.var.target_backend = canary.get_upstream()
            }

            proxy_pass http://$target_backend;
            proxy_set_header X-Backend $target_backend;
        }

        # 灰度管理接口
        location /admin/canary {
            content_by_lua_block {
                local cjson = require "cjson"
                ngx.req.read_body()
                local method = ngx.req.get_method()

                if method == "POST" then
                    local body = cjson.decode(ngx.req.get_body_data())
                    -- 更新灰度配置
                    local shared = ngx.shared.gateway_config
                    shared:set("canary_enabled", body.enabled or false)
                    shared:set("canary_percentage", body.percentage or 0)
                    ngx.say(cjson.encode({status = "updated"}))
                elseif method == "GET" then
                    local shared = ngx.shared.gateway_config
                    ngx.say(cjson.encode({
                        enabled = shared:get("canary_enabled"),
                        percentage = shared:get("canary_percentage"),
                    }))
                end
            }
        }
    }
}

-- /usr/local/openresty/lua/ab_testing.lua
local _M = {}

-- A/B 测试实验配置
local experiments = {
    {
        name = "new_search_algorithm",
        -- 流量分配
        variants = {
            {name = "control",  weight = 50, upstream = "search_v1"},
            {name = "variant_a", weight = 30, upstream = "search_v2"},
            {name = "variant_b", weight = 20, upstream = "search_v3"},
        },
        -- 参与条件
        conditions = {
            path = "^/api/search",
            method = "GET",
        },
    },
    {
        name = "checkout_flow",
        variants = {
            {name = "control", weight = 50, upstream = "checkout_v1"},
            {name = "new_flow", weight = 50, upstream = "checkout_v2"},
        },
        conditions = {
            path = "^/api/checkout",
        },
    },
}

-- 基于权重的随机选择
local function weighted_select(variants, seed)
    local hash = 0
    for i = 1, #seed do
        hash = (hash * 31 + string.byte(seed, i)) % 10000
    end

    local point = hash % 100
    local cumulative = 0

    for _, variant in ipairs(variants) do
        cumulative = cumulative + variant.weight
        if point < cumulative then
            return variant
        end
    end

    return variants[#variants]
end

function _M.route()
    local uri = ngx.var.uri
    local method = ngx.req.get_method()
    local user_id = ngx.var.http_x_user_id or ngx.var.remote_addr

    for _, exp in ipairs(experiments) do
        -- 检查是否参与实验
        local path_match = uri:match(exp.conditions.path)
        local method_match = (not exp.conditions.method) or (method == exp.conditions.method)

        if path_match and method_match then
            -- 选择变体
            local variant = weighted_select(exp.variants, user_id .. exp.name)

            -- 记录实验信息
            ngx.req.set_header("X-Experiment", exp.name)
            ngx.req.set_header("X-Variant", variant.name)

            -- Cookie 持久化（确保同一用户始终看到同一版本）
            local cookie_name = "ab_" .. exp.name
            local existing = ngx.var["cookie_" .. cookie_name]
            if existing then
                -- 使用已有的变体
                for _, v in ipairs(exp.variants) do
                    if v.name == existing then
                        variant = v
                        break
                    end
                end
            else
                -- 设置新 Cookie
                ngx.header["Set-Cookie"] = cookie_name .. "=" .. variant.name .. "; Path=/; Max-Age=86400"
            end

            return variant.upstream, exp.name, variant.name
        end
    end

    return nil, nil, nil
end

return _M

-- /usr/local/openresty/lua/dynamic_config.lua
local _M = {}

local cjson = require "cjson"

-- 配置版本号
local config_version = 0

-- 从共享内存加载路由配置
function _M.load_routes()
    local shared = ngx.shared.gateway_config
    local routes_json = shared:get("routes_json")

    if not routes_json then
        return nil, "No routes configured"
    end

    local new_version = shared:get("routes_version") or 0
    if new_version <= config_version then
        return nil, "Config not changed"
    end

    local routes = cjson.decode(routes_json)
    config_version = new_version
    return routes
end

-- Admin API 更新路由
function _M.update_routes(new_routes_json)
    local shared = ngx.shared.gateway_config
    local ok, err = shared:set("routes_json", new_routes_json)
    if not ok then
        return false, err
    end

    -- 递增版本号
    local new_version = (shared:get("routes_version") or 0) + 1
    shared:set("routes_version", new_version)

    -- 通知所有 Worker 刷新配置
    -- ngx.timer.at(0, function() _M.load_routes() end)

    return true, new_version
end

return _M

# Admin API
location /admin/routes {
    content_by_lua_block {
        local cjson = require "cjson"
        local dc = require "dynamic_config"
        local method = ngx.req.get_method()

        if method == "PUT" or method == "POST" then
            ngx.req.read_body()
            local body = ngx.req.get_body_data()
            local ok, result = dc.update_routes(body)
            if ok then
                ngx.say(cjson.encode({status = "ok", version = result}))
            else
                ngx.status = 500
                ngx.say(cjson.encode({error = result}))
            end
        elseif method == "GET" then
            local shared = ngx.shared.gateway_config
            local routes = shared:get("routes_json") or "{}"
            ngx.say(routes)
        end
    }
}