local comms        = require("scada-common.comms")
local log          = require("scada-common.log")
local mqueue       = require("scada-common.mqueue")
local types        = require("scada-common.types")
local util         = require("scada-common.util")

local unit_session = require("supervisor.session.rtu.unit_session")

local turbinev = {}

local RTU_UNIT_TYPES = comms.RTU_UNIT_TYPES
local DUMPING_MODE = types.DUMPING_MODE
local MODBUS_FCODE = types.MODBUS_FCODE

local TBV_RTU_S_CMDS = {
    INC_DUMP_MODE = 1,
    DEC_DUMP_MODE = 2
}

local TBV_RTU_S_DATA = {
    SET_DUMP_MODE = 1
}

turbinev.RS_RTU_S_CMDS = TBV_RTU_S_CMDS
turbinev.RS_RTU_S_DATA = TBV_RTU_S_DATA

local TXN_TYPES = {
    FORMED = 1,
    BUILD = 2,
    STATE = 3,
    TANKS = 4,
    INC_DUMP = 5,
    DEC_DUMP = 6,
    SET_DUMP = 7
}

local TXN_TAGS = {
    "turbinev.formed",
    "turbinev.build",
    "turbinev.state",
    "turbinev.tanks",
    "turbinev.inc_dump",
    "turbinev.dec_dump",
    "turbinev.set_dump"
}

local PERIODICS = {
    FORMED = 2000,
    BUILD = 1000,
    STATE = 500,
    TANKS = 1000
}

-- create a new turbinev rtu session runner
---@param session_id integer
---@param unit_id integer
---@param advert rtu_advertisement
---@param out_queue mqueue
function turbinev.new(session_id, unit_id, advert, out_queue)
    -- type check
    if advert.type ~= RTU_UNIT_TYPES.TURBINE_VALVE then
        log.error("attempt to instantiate turbinev RTU for type '" .. advert.type .. "'. this is a bug.")
        return nil
    end

    local log_tag = "session.rtu(" .. session_id .. ").turbinev(" .. advert.index .. "): "

    local self = {
        session = unit_session.new(unit_id, advert, out_queue, log_tag, TXN_TAGS),
        in_q = mqueue.new(),
        has_build = false,
        periodics = {
            next_formed_req = 0,
            next_build_req = 0,
            next_state_req = 0,
            next_tanks_req = 0
        },
        ---@class turbinev_session_db
        db = {
            formed = false,
            build = {
                last_update = 0,
                length = 0,
                width = 0,
                height = 0,
                min_pos = { x = 0, y = 0, z = 0 },  ---@type coordinate
                max_pos = { x = 0, y = 0, z = 0 },  ---@type coordinate
                blades = 0,
                coils = 0,
                vents = 0,
                dispersers = 0,
                condensers = 0,
                steam_cap = 0,
                max_energy = 0,
                max_flow_rate = 0,
                max_production = 0,
                max_water_output = 0
            },
            state = {
                last_update = 0,
                flow_rate = 0,
                prod_rate = 0,
                steam_input_rate = 0,
                dumping_mode = DUMPING_MODE.IDLE    ---@type DUMPING_MODE
            },
            tanks = {
                last_update = 0,
                steam = { type = "mekanism:empty_gas", amount = 0 }, ---@type tank_fluid
                steam_need = 0,
                steam_fill = 0.0,
                energy = 0,
                energy_need = 0,
                energy_fill = 0.0
            }
        }
    }

    local public = self.session.get()

    -- PRIVATE FUNCTIONS --

    -- increment the dumping mode
    local function _inc_dump_mode()
        -- write coil 1 with unused value 0
        self.session.send_request(TXN_TYPES.INC_DUMP, MODBUS_FCODE.WRITE_SINGLE_COIL, { 1, 0 })
    end

    -- decrement the dumping mode
    local function _dec_dump_mode()
        -- write coil 2 with unused value 0
        self.session.send_request(TXN_TYPES.DEC_DUMP, MODBUS_FCODE.WRITE_SINGLE_COIL, { 2, 0 })
    end

    -- set the dumping mode
    ---@param mode DUMPING_MODE
    local function _set_dump_mode(mode)
        -- write holding register 1
        self.session.send_request(TXN_TYPES.SET_DUMP, MODBUS_FCODE.WRITE_SINGLE_HOLD_REG, { 1, mode })
    end

    -- query if the multiblock is formed
    local function _request_formed()
        -- read discrete input 1 (start = 1, count = 1)
        self.session.send_request(TXN_TYPES.FORMED, MODBUS_FCODE.READ_DISCRETE_INPUTS, { 1, 1 })
    end

    -- query the build of the device
    local function _request_build()
        -- read input registers 1 through 15 (start = 1, count = 15)
        self.session.send_request(TXN_TYPES.BUILD, MODBUS_FCODE.READ_INPUT_REGS, { 1, 15 })
    end

    -- query the state of the device
    local function _request_state()
        -- read input registers 16 through 19 (start = 16, count = 4)
        self.session.send_request(TXN_TYPES.STATE, MODBUS_FCODE.READ_INPUT_REGS, { 16, 4 })
    end

    -- query the tanks of the device
    local function _request_tanks()
        -- read input registers 20 through 25 (start = 20, count = 6)
        self.session.send_request(TXN_TYPES.TANKS, MODBUS_FCODE.READ_INPUT_REGS, { 20, 6 })
    end

    -- PUBLIC FUNCTIONS --

    -- handle a packet
    ---@param m_pkt modbus_frame
    function public.handle_packet(m_pkt)
        local txn_type = self.session.try_resolve(m_pkt)
        if txn_type == false then
            -- nothing to do
        elseif txn_type == TXN_TYPES.FORMED then
            -- formed response
            -- load in data if correct length
            if m_pkt.length == 1 then
                self.db.formed = m_pkt.data[1]
            else
                log.debug(log_tag .. "MODBUS transaction reply length mismatch (" .. TXN_TAGS[txn_type] .. ")")
            end
        elseif txn_type == TXN_TYPES.BUILD then
            -- build response
            if m_pkt.length == 15 then
                self.db.build.last_update      = util.time_ms()
                self.db.build.length           = m_pkt.data[1]
                self.db.build.width            = m_pkt.data[2]
                self.db.build.height           = m_pkt.data[3]
                self.db.build.min_pos          = m_pkt.data[4]
                self.db.build.max_pos          = m_pkt.data[5]
                self.db.build.blades           = m_pkt.data[6]
                self.db.build.coils            = m_pkt.data[7]
                self.db.build.vents            = m_pkt.data[8]
                self.db.build.dispersers       = m_pkt.data[9]
                self.db.build.condensers       = m_pkt.data[10]
                self.db.build.steam_cap        = m_pkt.data[11]
                self.db.build.max_energy       = m_pkt.data[12]
                self.db.build.max_flow_rate    = m_pkt.data[13]
                self.db.build.max_production   = m_pkt.data[14]
                self.db.build.max_water_output = m_pkt.data[15]
                self.has_build = true

                out_queue.push_command(unit_session.RTU_US_CMDS.BUILD_CHANGED)
            else
                log.debug(log_tag .. "MODBUS transaction reply length mismatch (" .. TXN_TAGS[txn_type] .. ")")
            end
        elseif txn_type == TXN_TYPES.STATE then
            -- state response
            if m_pkt.length == 4 then
                self.db.state.last_update      = util.time_ms()
                self.db.state.flow_rate        = m_pkt.data[1]
                self.db.state.prod_rate        = m_pkt.data[2]
                self.db.state.steam_input_rate = m_pkt.data[3]
                self.db.state.dumping_mode     = m_pkt.data[4]
            else
                log.debug(log_tag .. "MODBUS transaction reply length mismatch (" .. TXN_TAGS[txn_type] .. ")")
            end
        elseif txn_type == TXN_TYPES.TANKS then
            -- tanks response
            if m_pkt.length == 6 then
                self.db.tanks.last_update = util.time_ms()
                self.db.tanks.steam       = m_pkt.data[1]
                self.db.tanks.steam_need  = m_pkt.data[2]
                self.db.tanks.steam_fill  = m_pkt.data[3]
                self.db.tanks.energy      = m_pkt.data[4]
                self.db.tanks.energy_need = m_pkt.data[5]
                self.db.tanks.energy_fill = m_pkt.data[6]
            else
                log.debug(log_tag .. "MODBUS transaction reply length mismatch (" .. TXN_TAGS[txn_type] .. ")")
            end
        elseif txn_type == TXN_TYPES.INC_DUMP or txn_type == TXN_TYPES.DEC_DUMP or txn_type == TXN_TYPES.SET_DUMP then
            -- successful acknowledgement
        elseif txn_type == nil then
            log.error(log_tag .. "unknown transaction reply")
        else
            log.error(log_tag .. "unknown transaction type " .. txn_type)
        end
    end

    -- update this runner
    ---@param time_now integer milliseconds
    function public.update(time_now)
        -- check command queue
        while self.in_q.ready() do
            -- get a new message to process
            local msg = self.in_q.pop()

            if msg ~= nil then
                if msg.qtype == mqueue.TYPE.COMMAND then
                    -- instruction
                    local cmd = msg.message

                    if cmd == TBV_RTU_S_CMDS.INC_DUMP_MODE then
                        _inc_dump_mode()
                    elseif cmd == TBV_RTU_S_CMDS.DEC_DUMP_MODE then
                        _dec_dump_mode()
                    else
                        log.debug(util.c(log_tag, "unrecognized in_q command ", cmd))
                    end
                elseif msg.qtype == mqueue.TYPE.DATA then
                    -- instruction with body
                    local cmd = msg.message     ---@type queue_data
                    if cmd.key == TBV_RTU_S_DATA.SET_DUMP_MODE then
                        _set_dump_mode(cmd.val)
                    else
                        log.debug(util.c(log_tag, "unrecognized in_q data ", cmd.key))
                    end
                end
            end

            -- max 100ms spent processing queue
            if util.time() - time_now > 100 then
                log.warning(log_tag .. "exceeded 100ms queue process limit")
                break
            end
        end

        time_now = util.time()

        -- handle periodics

        if self.periodics.next_formed_req <= time_now then
            _request_formed()
            self.periodics.next_formed_req = time_now + PERIODICS.FORMED
        end

        if self.db.formed then
            if not self.has_build and self.periodics.next_build_req <= time_now then
                _request_build()
                self.periodics.next_build_req = time_now + PERIODICS.BUILD
            end

            if self.periodics.next_state_req <= time_now then
                _request_state()
                self.periodics.next_state_req = time_now + PERIODICS.STATE
            end

            if self.periodics.next_tanks_req <= time_now then
                _request_tanks()
                self.periodics.next_tanks_req = time_now + PERIODICS.TANKS
            end
        end

        self.session.post_update()
    end

    -- invalidate build cache
    function public.invalidate_cache()
        self.periodics.next_formed_req = 0
        self.periodics.next_build_req = 0
        self.has_build = false
    end

    -- get the unit session database
    function public.get_db() return self.db end

    return public, self.in_q
end

return turbinev