--[[
@module  uart_app
@summary vd960Air 串口应用: UART1 对接 vd960DBN(0x7F 帧) → 标准 JSON 上报(方案 C)
@version 0.3
@date    2026.08.31
@usage
上行链路(方案 C):
  vd960Loop --0x7F帧--> vd960DBN --原样转发(UART1)--> Air780
  → frame_parser 解析 0x7F 帧
  → 0xC0 传感帧: proto_conv 解析 → loop_data JSON(注入 link)发布
  → car_state/loop_state 沿检测: evt_queue 入队 → event_report 发布(ACK 机制)
下行链路:
  MQTT 标准 JSON 命令 → (P1: 转 0x7F 帧) → UART1 → vd960DBN → vd960Loop
MVP 范围: 上行(initialize/loop_data/event_report/heartbeat)+ report_config 时钟校准;
  下行命令转换与 0x7D 配置同步列入 P1。
]]

-- 依赖
local CFG = require "config"
local link_info = require "link_info"
local frame_parser = require "frame_parser"
local proto_conv = require "proto_conv"
local evt_queue = require "evt_queue"
local clock = require "clock"

local uart_app = {}

local UART_ID = CFG.CFG_UART_ID

-- ==================== 公共工具 ====================
-- 上行 JSON 注入 link 对象(4G 特有字段)
local function inject_link(payload)
    if CFG.CFG_LINK_ENABLE then
        local ok, obj = pcall(json.decode, payload)
        if ok and type(obj) == "table" then
            obj.link = link_info.get()
            return json.encode(obj)
        end
    end
    return payload
end

-- 组 loop_data JSON(协议 §5.2)
local function build_loop_data(channels, ts, msg_id)
    local parts = {}
    for i = 1, #channels do
        local c = channels[i]
        parts[i] = string.format(
            '{"ch":%d,"level":"%s","iscar":%s,"loop_ok":%s,"freq":%d,"diff":%d,'
            .. '"sens":%d,"cndtn":%d,"misc":{"type":"%s","value":%d}}',
            c.ch, c.level, tostring(c.iscar), tostring(c.loop_ok),
            c.freq, c.diff, c.sens, c.cndtn, c.misc.type, c.misc.value)
    end
    return string.format('{"msg_id":%d,"cmd":"loop_data","ts":%d,"data":{"channels":[%s]}}',
                         msg_id, ts, table.concat(parts, ","))
end

-- 发布 event_report(新发或重发)
local function publish_event()
    local pend_id, pend_n, pend_ts = evt_queue.pending_info()
    local ts
    if pend_n and pend_n > 0 then
        ts = pend_ts                -- 重发: 原始 ts,msg_id 不变
    else
        ts = clock.now()            -- 新发
    end
    local payload = evt_queue.build_report(ts)
    if not payload then
        return
    end
    payload = inject_link(payload)
    sys.publish("SEND_DATA_REQ", "vd960DBN", CFG.CFG_TOPIC_UP, payload, 1)
    local id = evt_queue.last_msg_id()
    evt_queue.mark_sent(id, evt_queue.count(), ts, mstick())
    log.info("uart_app.evt", "pub id", id, "n", evt_queue.count(), "ts", ts)
end

-- ==================== 0x7F 帧回调 ====================
-- 独立 loop_data msg_id 计数
local g_ld_msg_id = 0
local function next_ld_msg_id()
    g_ld_msg_id = g_ld_msg_id + 1
    return g_ld_msg_id
end

-- 最近通道状态缓存(heartbeat 的 loop_status 用)
local last_loop_ok = { true, true, true, true }

local function on_frame(cmd, payload)
    if cmd == 0xC0 then
        -- 多线圈传感帧 → loop_data + 沿检测事件
        local channels = proto_conv.parse_sensor(payload)
        if not channels then
            return
        end
        -- 刷新 loop_status 缓存
        for i = 1, #channels do
            last_loop_ok[i] = channels[i].loop_ok
        end
        -- 沿检测 → 事件入队(返回是否需要立即发布)
        local need_evt = false
        local events = proto_conv.detect_events(channels)
        for i = 1, #events do
            need_evt = evt_queue.enqueue(events[i]) or need_evt
        end
        -- loop_data 上报(带 link)
        local ts = clock.now()
        local ld = inject_link(build_loop_data(channels, ts, next_ld_msg_id()))
        sys.publish("SEND_DATA_REQ", "vd960DBN", CFG.CFG_TOPIC_UP, ld, 0)
        -- 事件发布
        if need_evt then
            publish_event()
        end
    else
        -- 其他 0x7F 帧(命令响应等): P1 下行命令转换实现后处理
        log.info("uart_app.frame", "cmd", string.format("0x%02X", cmd), "len", payload:len())
    end
end

-- ==================== UART 接收 ====================
local function read()
    local s
    while true do
        s = uart.read(UART_ID, 1024)
        if not s or s:len() == 0 then
            break
        end
        for i = 1, s:len() do
            frame_parser.feed(string.byte(s, i))
        end
    end
end

-- ==================== 对外接口 ====================
-- MQTT 重连后: 未决事件包立即重发
function uart_app.on_mqtt_reconnect()
    local action = evt_queue.on_reconnect(mstick())
    if action == "resend" then
        publish_event()
    end
end

-- 平台 ACK(事件确认)路由
function uart_app.handle_event_ack(msg_id, code)
    evt_queue.handle_ack(msg_id, code)
end

-- 主循环驱动: 事件重发超时检查
function uart_app.poll()
    local action = evt_queue.poll(mstick())
    if action == "resend" then
        publish_event()
    end
end

-- 上报当前传感缓存? MVP: 心跳带 loop_status 由 mqtt_main 维护,此处暂不提供

-- heartbeat 用: 最近 4 路线圈状态(true=正常)
function uart_app.get_loop_status()
    return last_loop_ok
end

-- ==================== 初始化 ====================
frame_parser.init(on_frame)
uart.setup(UART_ID, CFG.CFG_UART_BAUD, 8, 1)
uart.on(UART_ID, "receive", read)

log.info("uart_app", "init ok", "baud", CFG.CFG_UART_BAUD, "topic_up", CFG.CFG_TOPIC_UP)

return uart_app