package econetclient

import (
	"encoding/json"
	"strconv"
	"strings"
	"time"
)

// Device is a flat snapshot of one piece of Rheem equipment, decoded from
// the getUserDataForApp REST response. Fields are computed once per refresh;
// consumers read them directly. WiFiSignal only arrives over MQTT (which this
// client does not use), so it stays at its zero value.
type Device struct {
	SerialNumber string
	DeviceID     string
	FriendlyName string
	Type         string // water_heater | thermostat | unknown
	GenericType  string // e.g. heatpumpWaterHeater, gasWaterHeater

	Connected  bool
	WiFiSignal int // MQTT-only; always 0 here
	Mode       string
	Enabled    bool

	Running      bool   // true when actively heating (decoded from @RUNNING over REST)
	RunningState string // normalized @RUNNING label: "compressor-running" | "element-running" | "idle" | ...

	Setpoint    int
	SetpointMin int
	SetpointMax int

	HotWaterAvailability int // -1 if not reported, else 0/33/66/100
	AlertCount           int
	Away                 bool

	LastUpdated time.Time

	// Usage totals for the current day, populated by Client.Refresh.
	EnergyKWH    float64
	EnergyType   string // "KWH" or "KBTU"
	WaterGallons float64
}

// newDevice decodes an equipment block (the raw JSON map for one unit) into
// a flat Device. It ports the accessor logic from kevinburke/rheemcloud-go
// so behaviour matches, minus the MQTT-only fields.
func newDevice(info map[string]json.RawMessage, now time.Time) *Device {
	d := &Device{
		DeviceID:             jsonStr(info["device_name"]),
		SerialNumber:         jsonStr(info["serial_number"]),
		Type:                 deviceTypeString(jsonStr(info["device_type"])),
		GenericType:          jsonStr(info["@TYPE"]),
		Connected:            connected(info),
		Away:                 jsonBool(info["@AWAY"]),
		AlertCount:           alertCount(info["@ALERTCOUNT"]),
		HotWaterAvailability: hotWater(info["@HOTWATER"]),
		Enabled:              enabled(info),
		Mode:                 mode(info),
		LastUpdated:          now,
	}
	d.FriendlyName = friendlyName(info, d.DeviceID)
	d.Setpoint, d.SetpointMin, d.SetpointMax = setpoint(info["@SETPOINT"])
	d.Running, d.RunningState = running(info)
	return d
}

// --- field decoders ------------------------------------------------------

func connected(info map[string]json.RawMessage) bool {
	v, ok := info["@CONNECTED"]
	if !ok {
		return true // older units omit it and are assumed connected
	}
	return jsonBool(v)
}

func friendlyName(info map[string]json.RawMessage, deviceID string) string {
	if obj := decodeDatapoint(info["@NAME"]); obj != nil {
		if s := jsonStr(obj.Value); s != "" {
			return s
		}
	}
	return deviceID
}

func alertCount(v json.RawMessage) int {
	if len(v) == 0 {
		return 0
	}
	var n float64
	if json.Unmarshal(v, &n) == nil {
		return int(n)
	}
	var s string
	if json.Unmarshal(v, &s) == nil {
		if i, err := strconv.Atoi(s); err == nil {
			return i
		}
	}
	return 0
}

func hotWater(v json.RawMessage) int {
	var icon string
	if len(v) == 0 || json.Unmarshal(v, &icon) != nil {
		return -1
	}
	switch {
	case strings.Contains(icon, "ic_tank_hundread_percent"):
		return 100
	case strings.Contains(icon, "ic_tank_fourty_percent"):
		return 66
	case strings.Contains(icon, "ic_tank_ten_percent"):
		return 33
	case strings.Contains(icon, "ic_tank_empty"), strings.Contains(icon, "ic_tank_zero_percent"):
		return 0
	default:
		return -1
	}
}

func setpoint(v json.RawMessage) (val, min, max int) {
	obj := decodeDatapoint(v)
	if obj == nil {
		return 0, 0, 0
	}
	var n float64
	_ = json.Unmarshal(obj.Value, &n)
	return int(n), int(obj.Constraints.LowerLimit), int(obj.Constraints.UpperLimit)
}

// enabled reports the master on/off state, porting rheemcloud's Device.Enabled.
func enabled(info map[string]json.RawMessage) bool {
	if _, ok := info["@MODE"]; ok {
		labels := modeLabels(info)
		if obj := decodeDatapoint(info["@MODE"]); obj != nil {
			if idx, ok := datapointIndex(obj); ok && idx >= 0 && idx < len(labels) {
				return !strings.EqualFold(labels[idx], "OFF")
			}
		}
	}
	if _, ok := info["@ENABLED"]; ok {
		obj := decodeDatapoint(info["@ENABLED"])
		if obj == nil {
			return false
		}
		idx, _ := datapointIndex(obj)
		return idx == 1
	}
	return false
}

// mode returns the current operating-mode label, porting rheemcloud's Device.Mode.
func mode(info map[string]json.RawMessage) string {
	_, supportsModes := info["@MODE"]
	_, supportsOnOff := info["@ENABLED"]
	if supportsOnOff && !enabled(info) {
		return "off"
	}
	if !supportsModes {
		switch jsonStr(info["@TYPE"]) {
		case "gasWaterHeater", "tanklessWaterHeater":
			return "gas"
		default:
			return "electric"
		}
	}
	labels := modeLabels(info)
	obj := decodeDatapoint(info["@MODE"])
	if obj == nil {
		return "unknown"
	}
	idx, _ := datapointIndex(obj)
	if idx < 0 || idx >= len(labels) {
		return "unknown"
	}
	return modeFromEnumText(labels[idx])
}

func modeLabels(info map[string]json.RawMessage) []string {
	obj := decodeDatapoint(info["@MODE"])
	if obj == nil {
		return nil
	}
	return obj.Constraints.EnumText
}

// modeFromEnumText normalizes a Rheem mode label into a stable slug,
// matching pyeconet's WaterHeaterOperationMode labels.
func modeFromEnumText(s string) string {
	cleaned := strings.ToUpper(strings.ReplaceAll(strings.ReplaceAll(strings.TrimRight(s, " "), " ", "_"), "/", "_"))
	switch cleaned {
	case "OFF":
		return "off"
	case "ELECTRIC", "ELECTRIC_MODE":
		return "electric"
	case "ENERGY_SAVING", "ENERGY_SAVER":
		return "energy-saving"
	case "HEAT_PUMP", "HEAT_PUMP_ONLY":
		return "heat-pump"
	case "HIGH_DEMAND":
		return "high-demand"
	case "GAS":
		return "gas"
	case "PERFORMANCE":
		return "performance"
	case "VACATION":
		return "vacation"
	default:
		return "unknown"
	}
}

// KnownModes are the normalized operating-mode slugs modeFromEnumText emits.
// Consumers (e.g. the mode enum gauge) iterate these so every mode gets a
// series regardless of which one is currently active.
var KnownModes = []string{
	"off", "electric", "energy-saving", "heat-pump",
	"high-demand", "gas", "performance", "vacation", "unknown",
}

// running reports whether the unit is actively heating and a normalized label
// for what is running. It reads the @RUNNING datapoint, a bare string the REST
// getUserDataForApp payload populates (e.g. "Compressor Running" -> true,
// "compressor-running"); empty means idle. This is served over plain REST
// despite older code assuming it was MQTT-only.
func running(info map[string]json.RawMessage) (active bool, state string) {
	raw := strings.TrimSpace(jsonStr(info["@RUNNING"]))
	if raw == "" {
		return false, "idle"
	}
	state = slugify(raw)
	if state == "off" || state == "idle" {
		return false, state
	}
	return true, state
}

// slugify normalizes a Rheem label into a stable lowercase kebab-case slug,
// e.g. "Compressor Running" -> "compressor-running".
func slugify(s string) string {
	s = strings.ToLower(strings.TrimSpace(s))
	s = strings.ReplaceAll(s, "/", "-")
	s = strings.Join(strings.Fields(s), "-")
	return s
}

func deviceTypeString(s string) string {
	switch s {
	case "WH":
		return "water_heater"
	case "HVAC":
		return "thermostat"
	default:
		return "unknown"
	}
}

// --- datapoint plumbing --------------------------------------------------

// datapointObject is the {value, status, title, constraints} shape many
// "@..." fields use. Some fields are bare scalars instead; decodeDatapoint
// returns nil for those and callers fall back to reading the raw value.
type datapointObject struct {
	Value       json.RawMessage      `json:"value"`
	Status      string               `json:"status"`
	Title       string               `json:"title"`
	Constraints datapointConstraints `json:"constraints"`
}

type datapointConstraints struct {
	LowerLimit float64  `json:"lowerLimit"`
	UpperLimit float64  `json:"upperLimit"`
	EnumText   []string `json:"enumText"`
}

func decodeDatapoint(b json.RawMessage) *datapointObject {
	if len(b) == 0 || !isJSONObject(b) {
		return nil
	}
	var obj datapointObject
	if json.Unmarshal(b, &obj) != nil {
		return nil
	}
	return &obj
}

// datapointIndex reads a datapoint's numeric value (mode index / enabled flag).
func datapointIndex(obj *datapointObject) (int, bool) {
	var n float64
	if json.Unmarshal(obj.Value, &n) != nil {
		return 0, false
	}
	return int(n), true
}

func isJSONObject(b json.RawMessage) bool {
	for _, c := range b {
		switch c {
		case ' ', '\t', '\n', '\r':
			continue
		case '{':
			return true
		default:
			return false
		}
	}
	return false
}

func jsonStr(v json.RawMessage) string {
	var s string
	_ = json.Unmarshal(v, &s)
	return s
}

func jsonBool(v json.RawMessage) bool {
	var b bool
	_ = json.Unmarshal(v, &b)
	return b
}