local audio  = require("scada-common.audio")
local const  = require("scada-common.constants")
local log    = require("scada-common.log")
local rsio   = require("scada-common.rsio")
local types  = require("scada-common.types")
local util   = require("scada-common.util")

local unit   = require("supervisor.unit")

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

local rsctl  = require("supervisor.session.rsctl")

local TONE           = audio.TONE

local ALARM          = types.ALARM
local PRIO           = types.ALARM_PRIORITY
local ALARM_STATE    = types.ALARM_STATE
local CONTAINER_MODE = types.CONTAINER_MODE
local PROCESS        = types.PROCESS
local PROCESS_NAMES  = types.PROCESS_NAMES
local RTU_UNIT_TYPE  = types.RTU_UNIT_TYPE
local WASTE_MODE     = types.WASTE_MODE
local WASTE          = types.WASTE_PRODUCT

local IO             = rsio.IO

local DTV_RTU_S_DATA = qtypes.DTV_RTU_S_DATA

-- 7.14 kJ per blade for 1 mB of fissile fuel<br>
-- 2856 FE per blade per 1 mB, 285.6 FE per blade per 0.1 mB (minimum)
local POWER_PER_BLADE = util.joules_to_fe(7140)

local FLOW_STABILITY_DELAY_S = const.FLOW_STABILITY_DELAY_MS / 1000

local ALARM_LIMS = const.ALARM_LIMITS

local AUTO_SCRAM = {
    NONE = 0,
    MATRIX_DC = 1,
    MATRIX_FILL = 2,
    CRIT_ALARM = 3,
    RADIATION = 4,
    GEN_FAULT = 5
}

local START_STATUS = {
    OK = 0,
    NO_UNITS = 1,
    BLADE_MISMATCH = 2
}

local charge_Kp = 0.15
local charge_Ki = 0.0
local charge_Kd = 0.6

local rate_Kp = 2.45
local rate_Ki = 0.4825
local rate_Kd = -1.0

---@class facility_management
local facility = {}

-- create a new facility management object
---@nodiscard
---@param config svr_config supervisor configuration
---@param cooling_conf sv_cooling_conf cooling configurations of reactor units
function facility.new(config, cooling_conf)
    local self = {
        units = {},
        status_text = { "START UP", "initializing..." },
        all_sys_ok = false,
        allow_testing = false,
        -- rtus
        rtu_conn_count = 0,
        rtu_list = {},
        redstone = {},
        induction = {},
        sps = {},
        tanks = {},
        envd = {},
        -- redstone I/O control
        io_ctl = nil,   ---@type rs_controller
        -- process control
        units_ready = false,
        mode = PROCESS.INACTIVE,
        last_mode = PROCESS.INACTIVE,
        return_mode = PROCESS.INACTIVE,
        mode_set = PROCESS.MAX_BURN,
        start_fail = START_STATUS.OK,
        max_burn_combined = 0.0,        -- maximum burn rate to clamp at
        burn_target = 0.1,              -- burn rate target for aggregate burn mode
        charge_setpoint = 0,            -- FE charge target setpoint
        gen_rate_setpoint = 0,          -- FE/t charge rate target setpoint
        group_map = {},                 -- units -> group IDs
        prio_defs = { {}, {}, {}, {} }, -- priority definitions (each level is a table of units)
        at_max_burn = false,
        ascram = false,
        ascram_reason = AUTO_SCRAM.NONE,
        ---@class ascram_status
        ascram_status = {
            matrix_dc = false,
            matrix_fill = false,
            crit_alarm = false,
            radiation = false,
            gen_fault = false
        },
        -- closed loop control
        charge_conversion = 1.0,
        time_start = 0.0,
        initial_ramp = true,
        waiting_on_ramp = false,
        waiting_on_stable = false,
        accumulator = 0.0,
        saturated = false,
        last_update = 0,
        last_error = 0.0,
        last_time = 0.0,
        -- waste processing
        waste_product = WASTE.PLUTONIUM,
        current_waste_product = WASTE.PLUTONIUM,
        pu_fallback = false,
        sps_low_power = false,
        disabled_sps = false,
        -- alarm tones
        tone_states = {},
        test_tone_set = false,
        test_tone_reset = false,
        test_tone_states = {},
        test_alarm_states = {},
        -- statistics
        im_stat_init = false,
        avg_charge = util.mov_avg(3),  -- 3 seconds
        avg_inflow = util.mov_avg(6),  -- 3 seconds
        avg_outflow = util.mov_avg(6), -- 3 seconds
        -- induction matrix charge delta stats
        avg_net = util.mov_avg(60),    -- 60 seconds
        imtx_last_capacity = 0,
        imtx_last_charge = 0,
        imtx_last_charge_t = 0,
        -- track faulted induction matrix update times to reject
        imtx_faulted_times = { 0, 0, 0 }
    }

    -- create units
    for i = 1, config.UnitCount do
        table.insert(self.units, unit.new(i, cooling_conf.r_cool[i].BoilerCount, cooling_conf.r_cool[i].TurbineCount, config.ExtChargeIdling))
        table.insert(self.group_map, 0)
    end

    -- list for RTU session management
    self.rtu_list = { self.redstone, self.induction, self.sps, self.tanks, self.envd }

    -- init redstone RTU I/O controller
    self.io_ctl = rsctl.new(self.redstone)

    -- fill blank alarm/tone states
    for _ = 1, 12 do table.insert(self.test_alarm_states, false) end
    for _ = 1, 8 do
        table.insert(self.tone_states, false)
        table.insert(self.test_tone_states, false)
    end

    -- PRIVATE FUNCTIONS --

    -- check if all auto-controlled units completed ramping
    ---@nodiscard
    local function _all_units_ramped()
        local all_ramped = true

        for i = 1, #self.prio_defs do
            local units = self.prio_defs[i]
            for u = 1, #units do
                all_ramped = all_ramped and units[u].auto_ramp_complete()
            end
        end

        return all_ramped
    end

    -- split a burn rate among the reactors
    ---@param burn_rate number burn rate assignment
    ---@param ramp boolean true to ramp, false to set right away
    ---@param abort_on_fault boolean? true to exit if one device has an effective burn rate different than its limit
    ---@return integer unallocated_br100, boolean? aborted
    local function _allocate_burn_rate(burn_rate, ramp, abort_on_fault)
        local unallocated = math.floor(burn_rate * 100)

        -- go through all priority groups
        for i = 1, #self.prio_defs do
            local units = self.prio_defs[i]

            if #units > 0 then
                local split = math.floor(unallocated / #units)

                local splits = {}
                for u = 1, #units do splits[u] = split end
                splits[#units] = splits[#units] + (unallocated % #units)

                -- go through all reactor units in this group
                for id = 1, #units do
                    local u = units[id] ---@type reactor_unit

                    local ctl = u.get_control_inf()
                    local lim_br100 = u.auto_get_effective_limit()

                    if abort_on_fault and (lim_br100 ~= ctl.lim_br100) then
                        -- effective limit differs from set limit, unit is degraded
                        return unallocated, true
                    end

                    local last = ctl.br100

                    if splits[id] <= lim_br100 then
                        ctl.br100 = splits[id]
                    else
                        ctl.br100 = lim_br100

                        if id < #units then
                            local remaining = #units - id
                            split = math.floor(unallocated / remaining)
                            for x = (id + 1), #units do splits[x] = split end
                            splits[#units] = splits[#units] + (unallocated % remaining)
                        end
                    end

                    unallocated = math.max(0, unallocated - ctl.br100)

                    if last ~= ctl.br100 then u.auto_commit_br100(ramp) end
                end
            end
        end

        return unallocated, false
    end

    -- set idle state of all assigned reactors
    ---@param idle boolean idle state
    local function _set_idling(idle)
        for i = 1, #self.prio_defs do
            for _, u in pairs(self.prio_defs[i]) do u.auto_set_idle(idle) end
        end
    end

    -- PUBLIC FUNCTIONS --

    ---@class facility
    local public = {}

    --#region Add/Link Devices

    -- link a redstone RTU session
    ---@param rs_unit unit_session
    function public.add_redstone(rs_unit) table.insert(self.redstone, rs_unit) end

    -- link an induction matrix RTU session
    ---@param imatrix unit_session
    ---@return boolean linked induction matrix accepted (max 1)
    function public.add_imatrix(imatrix)
        if #self.induction == 0 then
            table.insert(self.induction, imatrix)
            return true
        else return false end
    end

    -- link an SPS RTU session
    ---@param sps unit_session
    ---@return boolean linked SPS accepted (max 1)
    function public.add_sps(sps)
        if #self.sps == 0 then
            table.insert(self.sps, sps)
            return true
        else return false end
    end

    -- link a dynamic tank RTU session
    ---@param dynamic_tank unit_session
    function public.add_tank(dynamic_tank) table.insert(self.tanks, dynamic_tank) end

    -- link an environment detector RTU session
    ---@param envd unit_session
    function public.add_envd(envd) table.insert(self.envd, envd) end

    -- purge devices associated with the given RTU session ID
    ---@param session integer RTU session ID
    function public.purge_rtu_devices(session)
        for _, v in pairs(self.rtu_list) do util.filter_table(v, function (s) return s.get_session_id() ~= session end) end
    end

    --#endregion

    --#region Update

    -- update (iterate) the facility management
    function public.update()
        -- unlink RTU unit sessions if they are closed
        for _, v in pairs(self.rtu_list) do util.filter_table(v, function (u) return u.is_connected() end) end

        -- check if test routines are allowed right now
        self.allow_testing = true
        for i = 1, #self.units do
            local u = self.units[i] ---@type reactor_unit
            self.allow_testing = self.allow_testing and u.is_safe_idle()
        end

        -- current state for process control
        local charge_update = 0
        local rate_update = 0

        -- calculate moving averages for induction matrix
        if self.induction[1] ~= nil then
            local matrix = self.induction[1] ---@type unit_session
            local db = matrix.get_db()       ---@type imatrix_session_db

            local build_update = db.build.last_update
            rate_update = db.state.last_update
            charge_update = db.tanks.last_update

            local has_data = build_update > 0 and rate_update > 0 and charge_update > 0

            if matrix.is_faulted() then
                -- a fault occured, cannot reliably update stats
                has_data = false
                self.im_stat_init = false
                self.imtx_faulted_times = { build_update, rate_update, charge_update }
            elseif not self.im_stat_init then
                -- prevent operation with partially invalid data
                -- all fields must have updated since the last fault
                has_data = self.imtx_faulted_times[1] < build_update and
                           self.imtx_faulted_times[2] < rate_update and
                           self.imtx_faulted_times[3] < charge_update
            end

            if has_data then
                local energy = util.joules_to_fe(db.tanks.energy)
                local input  = util.joules_to_fe(db.state.last_input)
                local output = util.joules_to_fe(db.state.last_output)

                if self.im_stat_init then
                    self.avg_charge.record(energy, charge_update)
                    self.avg_inflow.record(input, rate_update)
                    self.avg_outflow.record(output, rate_update)

                    if charge_update ~= self.imtx_last_charge_t then
                        local delta = (energy - self.imtx_last_charge) / (charge_update - self.imtx_last_charge_t)

                        self.imtx_last_charge = energy
                        self.imtx_last_charge_t = charge_update

                        -- if the capacity changed, toss out existing data
                        if db.build.max_energy ~= self.imtx_last_capacity then
                            self.imtx_last_capacity = db.build.max_energy
                            self.avg_net.reset()
                        else
                            self.avg_net.record(delta, charge_update)
                        end
                    end
                else
                    self.im_stat_init = true

                    self.avg_charge.reset(energy)
                    self.avg_inflow.reset(input)
                    self.avg_outflow.reset(output)
                    self.avg_net.reset()

                    self.imtx_last_capacity = db.build.max_energy
                    self.imtx_last_charge = energy
                    self.imtx_last_charge_t = charge_update
                end
            else
                -- prevent use by control systems
                rate_update = 0
                charge_update = 0
            end
        else
            self.im_stat_init = false
        end

        self.all_sys_ok = true
        for i = 1, #self.units do
            self.all_sys_ok = self.all_sys_ok and not self.units[i].get_control_inf().degraded
        end

        -------------------------
        -- Run Process Control --
        -------------------------

        --#region

        local avg_charge  = self.avg_charge.compute()
        local avg_inflow  = self.avg_inflow.compute()
        local avg_outflow = self.avg_outflow.compute()

        local now = os.clock()

        local state_changed = self.mode ~= self.last_mode
        local next_mode = self.mode

        -- once auto control is started, sort the priority sublists by limits
        if state_changed then
            self.saturated = false

            log.debug(util.c("FAC: state changed from ", PROCESS_NAMES[self.last_mode + 1], " to ", PROCESS_NAMES[self.mode + 1]))

            if (self.last_mode == PROCESS.INACTIVE) or (self.last_mode == PROCESS.GEN_RATE_FAULT_IDLE) then
                self.start_fail = START_STATUS.OK

                if (self.mode ~= PROCESS.MATRIX_FAULT_IDLE) and (self.mode ~= PROCESS.SYSTEM_ALARM_IDLE) then
                    -- auto clear ASCRAM
                    self.ascram = false
                    self.ascram_reason = AUTO_SCRAM.NONE
                end

                local blade_count = nil
                self.max_burn_combined = 0.0

                for i = 1, #self.prio_defs do
                    table.sort(self.prio_defs[i],
                        ---@param a reactor_unit
                        ---@param b reactor_unit
                        function (a, b) return a.get_control_inf().lim_br100 < b.get_control_inf().lim_br100 end
                    )

                    for _, u in pairs(self.prio_defs[i]) do
                        local u_blade_count = u.get_control_inf().blade_count

                        if blade_count == nil then
                            blade_count = u_blade_count
                        elseif (u_blade_count ~= blade_count) and (self.mode == PROCESS.GEN_RATE) then
                            log.warning("FAC: cannot start GEN_RATE process with inconsistent unit blade counts")
                            next_mode = PROCESS.INACTIVE
                            self.start_fail = START_STATUS.BLADE_MISMATCH
                        end

                        if self.start_fail == START_STATUS.OK then u.auto_engage() end

                        self.max_burn_combined = self.max_burn_combined + (u.get_control_inf().lim_br100 / 100.0)
                    end
                end

                log.debug(util.c("FAC: computed a max combined burn rate of ", self.max_burn_combined, "mB/t"))

                if blade_count == nil then
                    -- no units
                    log.warning("FAC: cannot start process control with 0 units assigned")
                    next_mode = PROCESS.INACTIVE
                    self.start_fail = START_STATUS.NO_UNITS
                else
                    self.charge_conversion = blade_count * POWER_PER_BLADE
                end
            elseif self.mode == PROCESS.INACTIVE then
                for i = 1, #self.prio_defs do
                    -- disable reactors and disengage auto control
                    for _, u in pairs(self.prio_defs[i]) do
                        u.disable()
                        u.auto_set_idle(false)
                        u.auto_disengage()
                    end
                end

                log.info("FAC: disengaging auto control (now inactive)")
            end

            self.initial_ramp = true
            self.waiting_on_ramp = false
            self.waiting_on_stable = false
        else
            self.initial_ramp = false
        end

        -- update unit ready state
        local assign_count = 0
        self.units_ready = true
        for i = 1, #self.prio_defs do
            for _, u in pairs(self.prio_defs[i]) do
                assign_count = assign_count + 1
                self.units_ready = self.units_ready and u.get_control_inf().ready
            end
        end

        -- perform mode-specific operations
        if self.mode == PROCESS.INACTIVE then
            if not self.units_ready then
                self.status_text = { "NOT READY", "assigned units not ready" }
            else
                -- clear ASCRAM once ready
                self.ascram = false
                self.ascram_reason = AUTO_SCRAM.NONE

                if self.start_fail == START_STATUS.NO_UNITS and assign_count == 0 then
                    self.status_text = { "START FAILED", "no units were assigned" }
                elseif self.start_fail == START_STATUS.BLADE_MISMATCH then
                    self.status_text = { "START FAILED", "turbine blade count mismatch" }
                else
                    self.status_text = { "IDLE", "control disengaged" }
                end
            end
        elseif self.mode == PROCESS.MAX_BURN then
            -- run units at their limits
            if state_changed then
                self.time_start = now
                self.saturated = true

                self.status_text = { "MONITORED MODE", "running reactors at limit" }
                log.info("FAC: MAX_BURN process mode started")
            end

            _allocate_burn_rate(self.max_burn_combined, true)
        elseif self.mode == PROCESS.BURN_RATE then
            -- a total aggregate burn rate
            if state_changed then
                self.time_start = now
                self.status_text = { "BURN RATE MODE", "running" }
                log.info("FAC: BURN_RATE process mode started")
            end

            local unallocated = _allocate_burn_rate(self.burn_target, true)
            self.saturated = self.burn_target == self.max_burn_combined or unallocated > 0
        elseif self.mode == PROCESS.CHARGE then
            -- target a level of charge
            if state_changed then
                self.time_start = now
                self.last_time = now
                self.last_error = 0
                self.accumulator = 0

                -- enabling idling on all assigned units
                _set_idling(true)

                self.status_text = { "CHARGE MODE", "running control loop" }
                log.info("FAC: CHARGE mode starting PID control")
            elseif self.last_update < charge_update then
                -- convert to kFE to make constants not microscopic
                local error = util.round((self.charge_setpoint - avg_charge) / 1000) / 1000

                -- stop accumulator when saturated to avoid windup
                if not self.saturated then
                    self.accumulator = self.accumulator + (error * (now - self.last_time))
                end

                -- local runtime = now - self.time_start
                local integral = self.accumulator
                local derivative = (error - self.last_error) / (now - self.last_time)

                local P = charge_Kp * error
                local I = charge_Ki * integral
                local D = charge_Kd * derivative

                local output = P + I + D

                -- clamp at range -> output clamped (out_c)
                local out_c = math.max(0, math.min(output, self.max_burn_combined))

                self.saturated = output ~= out_c

                if not config.ExtChargeIdling then
                    -- stop idling early if the output is zero, we are at or above the setpoint, and are not losing charge
                    _set_idling(not ((out_c == 0) and (error <= 0) and (avg_outflow <= 0)))
                end

                -- log.debug(util.sprintf("CHARGE[%f] { CHRG[%f] ERR[%f] INT[%f] => OUT[%f] OUT_C[%f] <= P[%f] I[%f] D[%f] }",
                --     runtime, avg_charge, error, integral, output, out_c, P, I, D))

                _allocate_burn_rate(out_c, true)

                self.last_time = now
                self.last_error = error
            end

            self.last_update = charge_update
        elseif self.mode == PROCESS.GEN_RATE then
            -- target a rate of generation
            if state_changed then
                -- estimate an initial output
                local output = self.gen_rate_setpoint / self.charge_conversion

                local unallocated = _allocate_burn_rate(output, true)

                self.saturated = output >= self.max_burn_combined or unallocated > 0
                self.waiting_on_ramp = true

                self.status_text = { "GENERATION MODE", "starting up" }
                log.info(util.c("FAC: GEN_RATE process mode initial ramp started (initial target is ", output, " mB/t)"))
            elseif self.waiting_on_ramp then
                if _all_units_ramped() then
                    self.waiting_on_ramp = false
                    self.waiting_on_stable = true

                    self.time_start = now

                    self.status_text = { "GENERATION MODE", "holding ramped rate" }
                    log.info("FAC: GEN_RATE process mode initial ramp completed, holding for stablization time")
                end
            elseif self.waiting_on_stable then
                if (now - self.time_start) > FLOW_STABILITY_DELAY_S then
                    self.waiting_on_stable = false

                    self.time_start = now
                    self.last_time = now
                    self.last_error = 0
                    self.accumulator = 0

                    self.status_text = { "GENERATION MODE", "running control loop" }
                    log.info("FAC: GEN_RATE process mode initial hold completed, starting PID control")
                end
            elseif self.last_update < rate_update then
                -- convert to MFE (in rounded kFE) to make constants not microscopic
                local error = util.round((self.gen_rate_setpoint - avg_inflow) / 1000) / 1000

                -- stop accumulator when saturated to avoid windup
                if not self.saturated then
                    self.accumulator = self.accumulator + (error * (now - self.last_time))
                end

                -- local runtime = now - self.time_start
                local integral = self.accumulator
                local derivative = (error - self.last_error) / (now - self.last_time)

                local P = rate_Kp * error
                local I = rate_Ki * integral
                local D = rate_Kd * derivative

                -- velocity (rate) (derivative of charge level => rate) feed forward
                local FF = self.gen_rate_setpoint / self.charge_conversion

                local output = P + I + D + FF

                -- clamp at range -> output clamped (sp_c)
                local out_c = math.max(0, math.min(output, self.max_burn_combined))

                self.saturated = output ~= out_c

                -- log.debug(util.sprintf("GEN_RATE[%f] { RATE[%f] ERR[%f] INT[%f] => OUT[%f] OUT_C[%f] <= P[%f] I[%f] D[%f] }",
                --     runtime, avg_inflow, error, integral, output, out_c, P, I, D))

                _allocate_burn_rate(out_c, false)

                self.last_time = now
                self.last_error = error
            end

            self.last_update = rate_update
        elseif self.mode == PROCESS.MATRIX_FAULT_IDLE then
            -- exceeded charge, wait until condition clears
            if self.ascram_reason == AUTO_SCRAM.NONE then
                next_mode = self.return_mode
                log.info("FAC: exiting matrix fault idle state due to fault resolution")
            elseif self.ascram_reason == AUTO_SCRAM.CRIT_ALARM then
                next_mode = PROCESS.SYSTEM_ALARM_IDLE
                log.info("FAC: exiting matrix fault idle state due to critical unit alarm")
            end
        elseif self.mode == PROCESS.SYSTEM_ALARM_IDLE then
            -- do nothing, wait for user to confirm (stop and reset)
        elseif self.mode == PROCESS.GEN_RATE_FAULT_IDLE then
            -- system faulted (degraded/not ready) while running generation rate mode
            -- mode will need to be fully restarted once everything is OK to re-ramp to feed-forward
            if self.units_ready then
                log.info("FAC: system ready after faulting out of GEN_RATE process mode, switching back...")
                next_mode = PROCESS.GEN_RATE
            end
        elseif self.mode ~= PROCESS.INACTIVE then
            log.error(util.c("FAC: unsupported process mode ", self.mode, ", switching to inactive"))
            next_mode = PROCESS.INACTIVE
        end

        --#endregion

        ------------------------------
        -- Evaluate Automatic SCRAM --
        ------------------------------

        --#region

        local astatus = self.ascram_status

        if self.induction[1] ~= nil then
            local db = self.induction[1].get_db() ---@type imatrix_session_db

            -- clear matrix disconnected
            if astatus.matrix_dc then
                astatus.matrix_dc = false
                log.info("FAC: induction matrix reconnected, clearing ASCRAM condition")
            end

            -- check matrix fill too high
            local was_fill = astatus.matrix_fill
            astatus.matrix_fill = (db.tanks.energy_fill >= ALARM_LIMS.CHARGE_HIGH) or (astatus.matrix_fill and db.tanks.energy_fill > ALARM_LIMS.CHARGE_RE_ENABLE)

            if was_fill and not astatus.matrix_fill then
                log.info(util.c("FAC: charge state of induction matrix entered acceptable range <= ", ALARM_LIMS.CHARGE_RE_ENABLE * 100, "%"))
            end

            -- check for critical unit alarms
            astatus.crit_alarm = false
            for i = 1, #self.units do
                local u = self.units[i] ---@type reactor_unit

                if u.has_alarm_min_prio(PRIO.CRITICAL) then
                    astatus.crit_alarm = true
                    break
                end
            end

            -- check for facility radiation
            if #self.envd > 0 then
                local max_rad = 0

                for i = 1, #self.envd do
                    local envd = self.envd[i]  ---@type unit_session
                    local e_db = envd.get_db() ---@type envd_session_db
                    if e_db.radiation_raw > max_rad then max_rad = e_db.radiation_raw end
                end

                astatus.radiation = max_rad >= ALARM_LIMS.FAC_HIGH_RAD
            else
                -- don't clear, if it is true then we lost it with high radiation, so just keep alarming
                -- operator can restart the system or hit the stop/reset button
            end

            -- system not ready, will need to restart GEN_RATE mode
            -- clears when we enter the fault waiting state
            astatus.gen_fault = self.mode == PROCESS.GEN_RATE and not self.units_ready
        else
            astatus.matrix_dc = true
        end

        if (self.mode ~= PROCESS.INACTIVE) and (self.mode ~= PROCESS.SYSTEM_ALARM_IDLE) then
            local scram = astatus.matrix_dc or astatus.matrix_fill or astatus.crit_alarm or astatus.gen_fault

            if scram and not self.ascram then
                -- SCRAM all units
                for i = 1, #self.prio_defs do
                    for _, u in pairs(self.prio_defs[i]) do
                        u.auto_scram()
                    end
                end

                if astatus.crit_alarm then
                    -- highest priority alarm
                    next_mode = PROCESS.SYSTEM_ALARM_IDLE
                    self.ascram_reason = AUTO_SCRAM.CRIT_ALARM
                    self.status_text = { "AUTOMATIC SCRAM", "critical unit alarm tripped" }

                    log.info("FAC: automatic SCRAM due to critical unit alarm")
                    log.warning("FAC: emergency exit of process control due to critical unit alarm")
                elseif astatus.radiation then
                    next_mode = PROCESS.SYSTEM_ALARM_IDLE
                    self.ascram_reason = AUTO_SCRAM.RADIATION
                    self.status_text = { "AUTOMATIC SCRAM", "facility radiation high" }

                    log.info("FAC: automatic SCRAM due to high facility radiation")
                elseif astatus.matrix_dc then
                    next_mode = PROCESS.MATRIX_FAULT_IDLE
                    self.ascram_reason = AUTO_SCRAM.MATRIX_DC
                    self.status_text = { "AUTOMATIC SCRAM", "induction matrix disconnected" }

                    if self.mode ~= PROCESS.MATRIX_FAULT_IDLE then self.return_mode = self.mode end

                    log.info("FAC: automatic SCRAM due to induction matrix disconnection")
                elseif astatus.matrix_fill then
                    next_mode = PROCESS.MATRIX_FAULT_IDLE
                    self.ascram_reason = AUTO_SCRAM.MATRIX_FILL
                    self.status_text = { "AUTOMATIC SCRAM", "induction matrix fill high" }

                    if self.mode ~= PROCESS.MATRIX_FAULT_IDLE then self.return_mode = self.mode end

                    log.info("FAC: automatic SCRAM due to induction matrix high charge")
                elseif astatus.gen_fault then
                    -- lowest priority alarm
                    next_mode = PROCESS.GEN_RATE_FAULT_IDLE
                    self.ascram_reason = AUTO_SCRAM.GEN_FAULT
                    self.status_text = { "GENERATION MODE IDLE", "paused: system not ready" }

                    log.info("FAC: automatic SCRAM due to unit problem while in GEN_RATE mode, will resume once all units are ready")
                end
            end

            self.ascram = scram

            if not self.ascram then
                self.ascram_reason = AUTO_SCRAM.NONE

                -- reset PLC RPS trips if we should
                for i = 1, #self.units do
                    local u = self.units[i] ---@type reactor_unit
                    u.auto_cond_rps_reset()
                end
            end
        end

        --#endregion

        -- update last mode and set next mode
        self.last_mode = self.mode
        self.mode = next_mode

        -------------------------
        -- Handle Redstone I/O --
        -------------------------

        --#region

        if #self.redstone > 0 then
            -- handle facility SCRAM
            if self.io_ctl.digital_read(IO.F_SCRAM) then
                for i = 1, #self.units do
                    local u = self.units[i] ---@type reactor_unit
                    u.cond_scram()
                end
            end

            -- handle facility ack
            if self.io_ctl.digital_read(IO.F_ACK) then public.ack_all() end

            -- update facility alarm outputs
            local has_prio_alarm, has_any_alarm = false, false
            for i = 1, #self.units do
                local u = self.units[i] ---@type reactor_unit

                if u.has_alarm_min_prio(PRIO.EMERGENCY) then
                    has_prio_alarm, has_any_alarm = true, true
                    break
                elseif u.has_alarm_min_prio(PRIO.TIMELY) then
                    has_any_alarm = true
                end
            end

            self.io_ctl.digital_write(IO.F_ALARM, has_prio_alarm)
            self.io_ctl.digital_write(IO.F_ALARM_ANY, has_any_alarm)

            -- update induction matrix related outputs
            if self.induction[1] ~= nil then
                local db = self.induction[1].get_db() ---@type imatrix_session_db

                self.io_ctl.digital_write(IO.F_MATRIX_LOW, db.tanks.energy_fill < const.RS_THRESHOLDS.IMATRIX_CHARGE_LOW)
                self.io_ctl.digital_write(IO.F_MATRIX_HIGH, db.tanks.energy_fill > const.RS_THRESHOLDS.IMATRIX_CHARGE_HIGH)
                self.io_ctl.analog_write(IO.F_MATRIX_CHG, db.tanks.energy_fill, 0, 1)
            end
        end

        --#endregion

        ----------------
        -- Unit Tasks --
        ----------------

        --#region

        local insufficent_po_rate = false
        local need_emcool = false

        for i = 1, #self.units do
            local u = self.units[i] ---@type reactor_unit

            -- update auto waste processing
            if u.get_control_inf().waste_mode == WASTE_MODE.AUTO then
                if (u.get_sna_rate() * 10.0) < u.get_burn_rate() then
                    insufficent_po_rate = true
                end
            end

            -- check if unit activated emergency coolant & uses facility tanks
            if (cooling_conf.fac_tank_mode > 0) and u.is_emer_cool_tripped() and (cooling_conf.fac_tank_defs[i] == 2) then
                need_emcool = true
            end
        end

        -- update waste product

        self.current_waste_product = self.waste_product

        if (not self.sps_low_power) and (self.waste_product == WASTE.ANTI_MATTER) and (self.induction[1] ~= nil) then
            local db = self.induction[1].get_db() ---@type imatrix_session_db

            if db.tanks.energy_fill >= 0.15 then
                self.disabled_sps = false
            elseif self.disabled_sps or ((db.tanks.last_update > 0) and (db.tanks.energy_fill < 0.1)) then
                self.disabled_sps = true
                self.current_waste_product = WASTE.POLONIUM
            end
        else
            self.disabled_sps = false
        end

        if self.pu_fallback and insufficent_po_rate then
            self.current_waste_product = WASTE.PLUTONIUM
        end

        -- make sure dynamic tanks are allowing outflow if required
        -- set all, rather than trying to determine which is for which (simpler & safer)
        -- there should be no need for any to be in fill only mode
        if need_emcool then
            for i = 1, #self.tanks do
                local session = self.tanks[i]   ---@type unit_session
                local tank = session.get_db()   ---@type dynamicv_session_db

                if tank.state.container_mode == CONTAINER_MODE.FILL then
                    session.get_cmd_queue().push_data(DTV_RTU_S_DATA.SET_CONT_MODE, CONTAINER_MODE.BOTH)
                end
            end
        end

        --#endregion

        ------------------------
        -- Update Alarm Tones --
        ------------------------

        --#region

        local allow_test = self.allow_testing and self.test_tone_set

        local alarms = { false, false, false, false, false, false, false, false, false, false, false, false }

        -- reset tone states before re-evaluting
        for i = 1, #self.tone_states do self.tone_states[i] = false end

        if allow_test then
            alarms = self.test_alarm_states
        else
            -- check all alarms for all units
            for i = 1, #self.units do
                local u = self.units[i] ---@type reactor_unit
                for id, alarm in pairs(u.get_alarms()) do
                    alarms[id] = alarms[id] or (alarm == ALARM_STATE.TRIPPED)
                end
            end

            if not self.test_tone_reset then
                -- clear testing alarms if we aren't using them
                for i = 1, #self.test_alarm_states do self.test_alarm_states[i] = false end
            end
        end

        -- Evaluate Alarms --

        -- containment breach is worst case CRITICAL alarm, this takes priority
        if alarms[ALARM.ContainmentBreach] then
            self.tone_states[TONE.T_1800Hz_Int_4Hz] = true
        else
            -- critical damage is highest priority CRITICAL level alarm
            if alarms[ALARM.CriticalDamage] then
                self.tone_states[TONE.T_660Hz_Int_125ms] = true
            else
                -- EMERGENCY level alarms + URGENT over temp
                if alarms[ALARM.ReactorDamage] or alarms[ALARM.ReactorOverTemp] or alarms[ALARM.ReactorWasteLeak] then
                    self.tone_states[TONE.T_544Hz_440Hz_Alt] = true
                -- URGENT level turbine trip
                elseif alarms[ALARM.TurbineTrip] then
                    self.tone_states[TONE.T_745Hz_Int_1Hz] = true
                -- URGENT level reactor lost
                elseif alarms[ALARM.ReactorLost] then
                    self.tone_states[TONE.T_340Hz_Int_2Hz] = true
                -- TIMELY level alarms
                elseif alarms[ALARM.ReactorHighTemp] or alarms[ALARM.ReactorHighWaste] or alarms[ALARM.RCSTransient] then
                    self.tone_states[TONE.T_800Hz_Int] = true
                end
            end

            -- check RPS transient URGENT level alarm
            if alarms[ALARM.RPSTransient] then
                self.tone_states[TONE.T_1000Hz_Int] = true
                -- disable really painful audio combination
                self.tone_states[TONE.T_340Hz_Int_2Hz] = false
            end
        end

        -- radiation is a big concern, always play this CRITICAL level alarm if active
        if alarms[ALARM.ContainmentRadiation] then
            self.tone_states[TONE.T_800Hz_1000Hz_Alt] = true
            -- we are going to disable the RPS trip alarm audio due to conflict, and if it was enabled
            -- then we can re-enable the reactor lost alarm audio since it doesn't painfully combine with this one
            if self.tone_states[TONE.T_1000Hz_Int] and alarms[ALARM.ReactorLost] then self.tone_states[TONE.T_340Hz_Int_2Hz] = true end
            -- it sounds *really* bad if this is in conjunction with these other tones, so disable them
            self.tone_states[TONE.T_745Hz_Int_1Hz] = false
            self.tone_states[TONE.T_800Hz_Int] = false
            self.tone_states[TONE.T_1000Hz_Int] = false
        end

        -- add to tone states if testing is active
        if allow_test then
            for i = 1, #self.tone_states do
                self.tone_states[i] = self.tone_states[i] or self.test_tone_states[i]
            end

            self.test_tone_reset = false
        else
            if not self.test_tone_reset then
                -- clear testing tones if we aren't using them
                for i = 1, #self.test_tone_states do self.test_tone_states[i] = false end
            end

            -- flag that tones were reset
            self.test_tone_set = false
            self.test_tone_reset = true
        end

        --#endregion
    end

    -- call the update function of all units in the facility<br>
    -- additionally sets the requested auto waste mode if applicable
    function public.update_units()
        for i = 1, #self.units do
            local u = self.units[i] ---@type reactor_unit
            u.auto_set_waste(self.current_waste_product)
            u.update()
        end
    end

    --#endregion

    --#region Commands

    -- SCRAM all reactor units
    function public.scram_all()
        for i = 1, #self.units do
            local u = self.units[i] ---@type reactor_unit
            u.scram()
        end
    end

    -- ack all alarms on all reactor units
    function public.ack_all()
        for i = 1, #self.units do
            local u = self.units[i] ---@type reactor_unit
            u.ack_all()
        end
    end

    -- stop auto control
    function public.auto_stop() self.mode = PROCESS.INACTIVE end

    -- set automatic control configuration and start the process
    ---@param auto_cfg coord_auto_config configuration
    ---@return table response ready state (successfully started) and current configuration (after updating)
    function public.auto_start(auto_cfg)
        local charge_scaler = 1000000   -- convert MFE to FE
        local gen_scaler    = 1000      -- convert kFE to FE
        local ready         = false

        -- load up current limits
        local limits = {}
        for i = 1, config.UnitCount do
            local u = self.units[i] ---@type reactor_unit
            limits[i] = u.get_control_inf().lim_br100 * 100
        end

        -- only allow changes if not running
        if self.mode == PROCESS.INACTIVE then
            if (type(auto_cfg.mode) == "number") and (auto_cfg.mode > PROCESS.INACTIVE) and (auto_cfg.mode <= PROCESS.GEN_RATE) then
                self.mode_set = auto_cfg.mode
            end

            if (type(auto_cfg.burn_target) == "number") and auto_cfg.burn_target >= 0.1 then
                self.burn_target = auto_cfg.burn_target
            end

            if (type(auto_cfg.charge_target) == "number") and auto_cfg.charge_target >= 0 then
                self.charge_setpoint = auto_cfg.charge_target * charge_scaler
            end

            if (type(auto_cfg.gen_target) == "number") and auto_cfg.gen_target >= 0 then
                self.gen_rate_setpoint = auto_cfg.gen_target * gen_scaler
            end

            if (type(auto_cfg.limits) == "table") and (#auto_cfg.limits == config.UnitCount) then
                for i = 1, config.UnitCount do
                    local limit = auto_cfg.limits[i]

                    if (type(limit) == "number") and (limit >= 0.1) then
                        limits[i] = limit
                        self.units[i].set_burn_limit(limit)
                    end
                end
            end

            ready = self.mode_set > 0

            if (self.mode_set == PROCESS.CHARGE) and (self.charge_setpoint <= 0) or
               (self.mode_set == PROCESS.GEN_RATE) and (self.gen_rate_setpoint <= 0) or
               (self.mode_set == PROCESS.BURN_RATE) and (self.burn_target < 0.1) then
                ready = false
            end

            ready = ready and self.units_ready

            if ready then self.mode = self.mode_set end
        end

        return {
            ready,
            self.mode_set,
            self.burn_target,
            self.charge_setpoint / charge_scaler,
            self.gen_rate_setpoint / gen_scaler,
            limits
        }
    end

    --#endregion

    --#region Settings

    -- set the automatic control group of a unit
    ---@param unit_id integer unit ID
    ---@param group integer group ID or 0 for independent
    function public.set_group(unit_id, group)
        if (group >= 0 and group <= 4) and (unit_id > 0 and unit_id <= config.UnitCount) and self.mode == PROCESS.INACTIVE then
            -- remove from old group if previously assigned
            local old_group = self.group_map[unit_id]
            if old_group ~= 0 then
                util.filter_table(self.prio_defs[old_group], function (u) return u.get_id() ~= unit_id end)
            end

            self.group_map[unit_id] = group

            -- add to group if not independent
            if group > 0 then
                table.insert(self.prio_defs[group], self.units[unit_id])
            end
        end
    end

    -- set waste production
    ---@param product WASTE_PRODUCT target product
    ---@return WASTE_PRODUCT product newly set value, if valid
    function public.set_waste_product(product)
        if product == WASTE.PLUTONIUM or product == WASTE.POLONIUM or product == WASTE.ANTI_MATTER then
            self.waste_product = product
        end

        return self.waste_product
    end

    -- enable/disable plutonium fallback
    ---@param enabled boolean requested state
    ---@return boolean enabled newly set value
    function public.set_pu_fallback(enabled)
        self.pu_fallback = enabled == true
        return self.pu_fallback
    end

    -- enable/disable SPS at low power
    ---@param enabled boolean requested state
    ---@return boolean enabled newly set value
    function public.set_sps_low_power(enabled)
        self.sps_low_power = enabled == true
        return self.sps_low_power
    end

    --#endregion

    --#region Diagnostic Testing

    -- attempt to set a test tone state
    ---@param id TONE|0 tone ID or 0 to disable all
    ---@param state boolean state
    ---@return boolean allow_testing, table test_tone_states
    function public.diag_set_test_tone(id, state)
        if self.allow_testing then
            self.test_tone_set = true
            self.test_tone_reset = false

            if id == 0 then
                for i = 1, #self.test_tone_states do self.test_tone_states[i] = false end
            else
                self.test_tone_states[id] = state
            end
        end

        return self.allow_testing, self.test_tone_states
    end

    -- attempt to set a test alarm state
    ---@param id ALARM|0 alarm ID or 0 to disable all
    ---@param state boolean state
    ---@return boolean allow_testing, table test_alarm_states
    function public.diag_set_test_alarm(id, state)
        if self.allow_testing then
            self.test_tone_set = true
            self.test_tone_reset = false

            if id == 0 then
                for i = 1, #self.test_alarm_states do self.test_alarm_states[i] = false end
            else
                self.test_alarm_states[id] = state
            end
        end

        return self.allow_testing, self.test_alarm_states
    end

    --#endregion

    --#region Read States/Properties

    -- get current alarm tone on/off states
    ---@nodiscard
    function public.get_alarm_tones() return self.tone_states end

    -- get build properties of all facility devices
    ---@nodiscard
    ---@param type RTU_UNIT_TYPE? type or nil to include only a particular unit type, or to include all if nil
    function public.get_build(type)
        local all = type == nil
        local build = {}

        if all or type == RTU_UNIT_TYPE.IMATRIX then
            build.induction = {}
            for i = 1, #self.induction do
                local matrix = self.induction[i]    ---@type unit_session
                build.induction[i] = { matrix.get_db().formed, matrix.get_db().build }
            end
        end

        if all or type == RTU_UNIT_TYPE.SPS then
            build.sps = {}
            for i = 1, #self.sps do
                local sps = self.sps[i] ---@type unit_session
                build.sps[i] = { sps.get_db().formed, sps.get_db().build }
            end
        end

        if all or type == RTU_UNIT_TYPE.DYNAMIC_VALVE then
            build.tanks = {}
            for i = 1, #self.tanks do
                local tank = self.tanks[i]  ---@type unit_session
                build.tanks[tank.get_device_idx()] = { tank.get_db().formed, tank.get_db().build }
            end
        end

        return build
    end

    -- get automatic process control status
    ---@nodiscard
    function public.get_control_status()
        local astat = self.ascram_status
        return {
            self.all_sys_ok,
            self.units_ready,
            self.mode,
            self.waiting_on_ramp or self.waiting_on_stable,
            self.at_max_burn or self.saturated,
            self.ascram,
            astat.matrix_dc,
            astat.matrix_fill,
            astat.crit_alarm,
            astat.radiation,
            astat.gen_fault or self.mode == PROCESS.GEN_RATE_FAULT_IDLE,
            self.status_text[1],
            self.status_text[2],
            self.group_map,
            self.current_waste_product,
            self.pu_fallback and (self.current_waste_product == WASTE.PLUTONIUM) and (self.waste_product ~= WASTE.PLUTONIUM),
            self.disabled_sps
        }
    end

    -- get RTU statuses
    ---@nodiscard
    function public.get_rtu_statuses()
        local status = {}

        -- total count of all connected RTUs in the facility
        status.count = self.rtu_conn_count

        -- power averages from induction matricies
        status.power = {
            self.avg_charge.compute(),
            self.avg_inflow.compute(),
            self.avg_outflow.compute(),
            0
        }

        -- status of induction matricies (including tanks)
        status.induction = {}
        for i = 1, #self.induction do
            local matrix = self.induction[i] ---@type unit_session
            local db     = matrix.get_db()   ---@type imatrix_session_db

            status.induction[i] = { matrix.is_faulted(), db.formed, db.state, db.tanks }

            local fe_per_ms = self.avg_net.compute()
            local remaining = util.joules_to_fe(util.trinary(fe_per_ms >= 0, db.tanks.energy_need, db.tanks.energy))
            status.power[4] = remaining / fe_per_ms
        end

        -- status of sps
        status.sps = {}
        for i = 1, #self.sps do
            local sps = self.sps[i]     ---@type unit_session
            local db  = sps.get_db()    ---@type sps_session_db
            status.sps[i] = { sps.is_faulted(), db.formed, db.state, db.tanks }
        end

        -- status of dynamic tanks
        status.tanks = {}
        for i = 1, #self.tanks do
            local tank = self.tanks[i]  ---@type unit_session
            local db   = tank.get_db()  ---@type dynamicv_session_db
            status.tanks[tank.get_device_idx()] = { tank.is_faulted(), db.formed, db.state, db.tanks }
        end

        -- radiation monitors (environment detectors)
        status.envds = {}
        for i = 1, #self.envd do
            local envd = self.envd[i]   ---@type unit_session
            local db   = envd.get_db()  ---@type envd_session_db
            status.envds[envd.get_device_idx()] = { envd.is_faulted(), db.radiation, db.radiation_raw }
        end

        return status
    end

    --#endregion

    -- supervisor sessions reporting the list of active RTU sessions
    ---@param rtu_sessions table session list of all connected RTUs
    function public.report_rtus(rtu_sessions) self.rtu_conn_count = #rtu_sessions end

    -- get the units in this facility
    ---@nodiscard
    function public.get_units() return self.units end

    return public
end

return facility