module.exports = function(RED) {
    function thermostat(config) {
        RED.nodes.createNode(this,config);
        var node = this;
        var context = node.context();

        const HEAT_ON_THRESHOLD = 0.2
        const HEAT_OFF_THRESHOLD = 0.2

        let control_mode = context.get("control_mode") || "auto" //auto, on, off
        let current_temp = context.get("current_temp")
        let target_temp = context.get("target_temp") || 19
        let window_state = context.get("window_state") || "close" //open, close
        let window_mode = context.get("window_mode") || "cool" //heat, cool, off
        let heater_status = null
        let debug = ""


        function debug_text(text) {
            if (text === "return_debug") return debug
            debug = debug ? `${debug}, ${text}` : text
        }

        function predict_temp_change(current_temp, time_interval) {
            let last_temp = context.get('last_temp') || null
            let last_temp_time = context.get('last_temp_time') || null
            if (last_temp === null || last_temp_time === null) {
                last_temp = current_temp
                last_temp_time = new Date().getTime()
                context.set('last_temp', last_temp)
                context.set('last_temp_time', last_temp_time)
                return 0
            }

            const temp_diff = current_temp - last_temp
            const time_diff = (new Date().getTime() - last_temp_time) / 1000
            const rate_of_change = temp_diff / time_diff

            last_temp = current_temp
            last_temp_time = new Date().getTime()
            context.set('last_temp', last_temp)
            context.set('last_temp_time', last_temp_time)

            return current_temp + rate_of_change * time_interval
        }


        function logic() {
            if (control_mode === "off") {
                heater_status = 0
                debug_text("Heater: force/off")
                return
            }

            if (control_mode === "on") {
                heater_status = 1
                debug_text("Heater: force/on")
                return
            }

            if (control_mode === "auto-predict" && current_temp !== null && target_temp !== null) {
                const predicted_temp = predict_temp_change(current_temp, 40)
                if (window_state === "open" && window_mode === "cool") {
                    heater_status = 0
                    debug_text("Heater: w-open-cool/off")
                    return
                }
                if (window_state === "open" && window_mode === "heat") {
                    heater_status = 1
                    debug_text("Heater: w-open-heat/on")
                    return
                }

                if (window_state === "close") {
                    if (predicted_temp < target_temp) {
                        heater_status = 1
                        debug_text(`Heater: auto-predict/${"on"}`)
                    } else if (predicted_temp >= target_temp) {
                        heater_status = 0
                        debug_text(`Heater: auto-predict/${"off"}`)
                    }
                }
                return
            }

            if (control_mode === "auto" && current_temp !== null && target_temp !== null) {
                if (window_state === "open" && window_mode === "cool") {
                    heater_status = 0
                    debug_text("Heater: w-open-cool/off")
                    return
                }
                if (window_state === "open" && window_mode === "heat") {
                    heater_status = 1
                    debug_text("Heater: w-open-heat/on")
                    return
                }

                if (window_state === "close") {
                    if (current_temp <= target_temp - HEAT_ON_THRESHOLD) {
                        heater_status = 1
                        debug_text(`Heater: auto/${"on"}`)
                    } else if (current_temp >= target_temp + HEAT_OFF_THRESHOLD) {
                        heater_status = 0
                        debug_text(`Heater: auto/${"off"}`)
                    } else {
                        debug_text(`Heater: auto/${"hyst"}`)
                    }
                }
                return
            }
        }

        node.on('input', function(msg) {
            let topic = msg.topic
            let payload = msg.payload

            debug_text(`W-mode: ${window_mode}`)
            if (topic === "window_mode_control" && (payload === "cool" || payload === "heat" || payload === "off")) {
                window_mode = payload
                context.set("window_mode", window_mode)
            }

            if (topic === "control" && (payload === "on" || payload === "off" || payload === "auto" || payload === "auto-predict")) {
                control_mode = payload
                context.set("control_mode", control_mode)
            }

            debug_text(`W-state: ${window_state}`)
            if (topic === "window" && (payload === "open" || payload === "close")) {
                window_state = payload
                context.set("window_state", window_state)
            }

            if (topic === "target") {
                target_temp = parseFloat(msg.payload)
                context.set("target_temp", target_temp)
                debug_text(`Current: ${current_temp}`)
                debug_text(`Target: ${target_temp}`)
            }

            if (msg.topic === "current") {
                current_temp = parseFloat(msg.payload)
                context.set("current_temp", current_temp)
                debug_text(`Current: ${current_temp}`)
                debug_text(`Target: ${target_temp}`)
            }


            logic()


            let extended_stats = {
                "control_mode": control_mode,
                "current_temp": current_temp,
                "target_temp": target_temp,
                "window_state": window_state,
                "window_mode": window_mode,
                "heater_status": heater_status,
                "HEAT_ON_THRESHOLD": HEAT_ON_THRESHOLD,
                "HEAT_OFF_THRESHOLD": HEAT_OFF_THRESHOLD,
            }



            node.status({ text: debug_text("return_debug") })

            let msg_heater_status = { payload: heater_status }
            let msg_extended_stats = { payload: extended_stats }

            if (heater_status === null || typeof heater_status === "undefined") {
                msg_heater_status = null
            }

            node.send([msg_heater_status, msg_extended_stats]);
        });




    }
    RED.nodes.registerType("c-thermostat", thermostat );
}