local device = {
    model = "TLSR8258_AC_CONTROLLER",
    vendor = "Custom",
    description = "TuyaOS Mitsubishi AC serial controller (stateless)",
    fingerprint = {{model = "TS0601", manufacturer = "_TZ3000_fcfbx2rz"}},
}

local modes = {"cool", "dry", "fan_only", "auto"}
local fans = {"quiet", "low", "powerful", "max"}
local directions = {"position_1", "position_2", "position_3", "position_4", "position_5"}
local faults = {
    "communication", "eeprom", "test_run", "discharge_temperature", "low_pressure",
    "high_pressure", "refrigerant_overcharge", "drain_or_water_level", "water_leak",
    "power_supply", "fan", "compressor_or_ipm", "overheat_or_overload",
    "function_or_damper_setting", "temperature_sensor", "float_switch",
    "configuration", "other_or_unknown",
}
local schema = {
    [1] = {1, 1}, [2] = {2, 4}, [3] = {2, 4}, [4] = {4, 1},
    [5] = {4, 1}, [6] = {5, 4}, [101] = {4, 1},
}

local function decode(msg)
    if msg.is_attribute or msg.cluster ~= 0xEF00 then return nil end
    local command = msg.cmd_or_attr_id
    -- dataResponse, dataReport, activeStatusReport only.
    if command ~= 0x01 and command ~= 0x02 and command ~= 0x06 then return nil end
    local bytes = msg.payload
    if not bytes or #bytes < 2 then return nil end
    local result = {}
    local pos = 3 -- Skip Tuya sequence (two bytes).
    while pos <= #bytes do
        if pos + 3 > #bytes then return nil end
        local dp, datatype = bytes[pos], bytes[pos + 1]
        local length = bytes[pos + 2] * 256 + bytes[pos + 3]
        pos = pos + 4
        if pos + length - 1 > #bytes then return nil end
        local expected = schema[dp]
        if expected and datatype == expected[1] and length == expected[2] then
            local value = 0
            for i = pos, pos + length - 1 do value = value * 256 + bytes[i] end
            if dp == 1 and value <= 1 then
                result.state = value == 1 and "ON" or "OFF"
            elseif dp == 2 and value >= 16 and value <= 31 then
                result.occupied_cooling_setpoint = value
            elseif dp == 3 and value ~= 255 then
                result.local_temperature = value
            elseif dp == 4 and modes[value + 1] then
                result.ac_mode = modes[value + 1]
            elseif dp == 5 and fans[value + 1] then
                result.fan_mode = fans[value + 1]
            elseif dp == 101 and directions[value + 1] then
                result.air_direction = directions[value + 1]
            elseif dp == 6 then
                result.fault_code = value -- DP6 bitmap, not the original AC error code.
                result.fault = value ~= 0
                local names = {}
                for bit, name in ipairs(faults) do
                    if math.floor(value / 2 ^ (bit - 1)) % 2 == 1 then
                        names[#names + 1] = name
                    end
                end
                if value >= 0x40000 then names[#names + 1] = "unknown_bits" end
                result.fault_description = #names > 0 and table.concat(names, ", ") or "none"
            end
        end
        pos = pos + length
    end
    -- Deliberately no per-device or shared state cache. OFF takes precedence
    -- within this frame only. A standalone DP4 report directly updates mode;
    -- a standalone DP1=ON cannot tell us which mode the firmware restored.
    if result.state == "OFF" then
        result.system_mode = "off"
    elseif result.ac_mode then
        result.system_mode = result.ac_mode
    end
    return next(result) and result or nil
end

local function send(dp, datatype, data, endpoint)
    -- Same sequence placeholder as the gateway's built-in Tuya DP encoder.
    local payload = {0, 0, dp, datatype, 0, #data}
    for _, byte in ipairs(data) do payload[#payload + 1] = byte end
    return {cluster = 0xEF00, endpoint = endpoint or 1, command = 0x00, payload = payload}
end

local function enumValue(values, value)
    for i, name in ipairs(values) do
        if name == value then return i - 1 end
    end
    error("Unsupported enum value: " .. tostring(value))
end

device.fromZigbee = {{cluster = 0xEF00, convert = decode}}
-- The gateway calls setters separately: no whole-message validation or
-- optimistic derived state is possible through this Lua interface. Do not
-- combine conflicting state/system_mode fields in one /set message.
device.toZigbee = {
    {key = "state", convert = function(value, endpoint)
        assert(value == "ON" or value == "OFF", "state must be ON or OFF")
        return send(1, 1, {value == "ON" and 1 or 0}, endpoint)
    end},
    {key = "system_mode", convert = function(value, endpoint)
        if value == "off" then return send(1, 1, {0}, endpoint) end
        -- Firmware DP4 selects the mode AND turns the AC on, even from OFF.
        return send(4, 4, {enumValue(modes, value)}, endpoint)
    end},
    {key = "occupied_cooling_setpoint", convert = function(value, endpoint)
        assert(type(value) == "number" and value >= 16 and value <= 31
            and value == math.floor(value), "Temperature must be an integer from 16 to 31 C")
        return send(2, 2, {0, 0, 0, value}, endpoint)
    end},
    {key = "fan_mode", convert = function(value, endpoint)
        return send(5, 4, {enumValue(fans, value)}, endpoint)
    end},
    {key = "air_direction", convert = function(value, endpoint)
        return send(101, 4, {enumValue(directions, value)}, endpoint)
    end},
}

device.exposes = {
    -- Use the gateway's switch composite so HA exposes a controllable power
    -- switch, rather than treating a top-level binary expose as a sensor.
    {type = "switch", features = {
        {type = "binary", name = "state", property = "state", access = 3,
         value_on = "ON", value_off = "OFF",
         description = "Power; ON restores the firmware operating mode"},
    }},
    {type = "climate", features = {
        {type = "numeric", name = "occupied_cooling_setpoint",
         property = "occupied_cooling_setpoint", access = 3,
         min = 16, max = 31, value_step = 1, unit = "°C"},
        {type = "numeric", name = "local_temperature", property = "local_temperature",
         access = 1, unit = "°C"},
        {type = "enum", name = "system_mode", property = "system_mode", access = 3,
         values = {"off", "cool", "dry", "fan_only", "auto"}},
        {type = "enum", name = "fan_mode", property = "fan_mode", access = 3, values = fans},
    }},
    {type = "enum", name = "air_direction", property = "air_direction", access = 3,
     values = directions, description = "Five fixed vane positions; swing is not supported"},
    {type = "enum", name = "ac_mode", property = "ac_mode", access = 1, values = modes,
     description = "Reported DP4 mode; OFF takes precedence only within the same report"},
    {type = "binary", name = "fault", property = "fault", access = 1,
     value_on = "true", value_off = "false", category = "diagnostic"},
    {type = "numeric", name = "fault_code", property = "fault_code", access = 1,
     description = "DP6 fault bitmap, not the original AC error code", category = "diagnostic"},
    {type = "text", name = "fault_description", property = "fault_description",
     access = 1, category = "diagnostic"},
}

-- No configure, magic packet, polling or configuration writes: firmware reports
-- on join, periodically, on AC state changes and after accepted commands.
return device