package onboarding

import (
	"context"
	"encoding/json"
	"errors"
	"strings"

	"data-terminal-cloud/internal/device"
	"data-terminal-cloud/internal/deviceauth"
	"data-terminal-cloud/internal/deviceconfig"
	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
)

// These routes use DEVREQ1 factory authentication. A device never supplies the
// platform UUID or tenant used to read configurations or acknowledge commands.
type DeviceControlReport struct {
	Firmware    string             `json:"firmware_version"`
	Revision    int64              `json:"reported_revision"`
	Speaker     int                `json:"speaker"`
	Busy        bool               `json:"busy"`
	RSSI        int                `json:"rssi"`
	DisplayName *string            `json:"display_name,omitempty"`
	Power       *DevicePowerReport `json:"power,omitempty"`
	ScreenWake  *DeviceScreenWake  `json:"screen_wake,omitempty"`
}

type DeviceScreenWake struct {
	ID       string `json:"id"`
	Revision int64  `json:"revision"`
}

type DeviceScreenWakeReceipt struct {
	DeviceScreenWake
	Result string `json:"result"`
}

type DevicePowerReport struct {
	Mode             string `json:"mode"`
	MicrophonePaused bool   `json:"microphone_paused"`
	BacklightPercent int    `json:"backlight_percent"`
	MicrophoneReads  uint64 `json:"microphone_reads"`
}

func controlIdentity(d Device) deviceauth.Identity {
	return deviceauth.Identity{ID: d.ID, PublicID: d.PublicID, TenantID: d.TenantID,
		Status: d.Status, ActivationState: d.Lifecycle, EnrollmentMode: d.Mode,
		BindingGeneration: d.Generation}
}

func validateControlReport(in DeviceControlReport) error {
	if wake := in.ScreenWake; wake != nil {
		if _, err := uuid.Parse(wake.ID); err != nil || len(wake.ID) != 36 || wake.Revision <= 0 ||
			in.Power == nil || in.Power.Mode != "active" {
			return fail(400, "INVALID_CONTROL_REPORT", "屏幕唤醒状态不正确")
		}
	}
	if p := in.Power; p != nil {
		if p.BacklightPercent < -1 || p.BacklightPercent > 100 || p.MicrophoneReads > 4294967295 ||
			(p.Mode != "active" && p.Mode != "standby" && p.Mode != "transition") ||
			(p.Mode == "standby" && (!p.MicrophonePaused || p.BacklightPercent != 0)) ||
			(p.Mode == "active" && (p.MicrophonePaused || p.BacklightPercent <= 0)) {
			return fail(400, "INVALID_CONTROL_REPORT", "待机状态不正确")
		}
	}
	if in.DisplayName != nil && !deviceconfig.ValidDisplayName(*in.DisplayName) {
		return fail(400, "INVALID_CONTROL_REPORT", "设备名称不正确")
	}
	if in.Firmware == "" || len(in.Firmware) > 80 || strings.TrimSpace(in.Firmware) != in.Firmware ||
		in.Revision < 0 || in.Speaker < 0 || in.Speaker > 100 || in.RSSI < -127 || in.RSSI > 0 {
		return fail(400, "INVALID_CONTROL_REPORT", "设备运行状态不正确")
	}
	return nil
}

// An authenticated physical wake only changes power. A revision fence prevents
// an offline gesture or a lost-response retry from undoing newer cloud settings.
// Its receipt and the actual report commit with the desired state under one lock.
func reconcileScreenWake(ctx context.Context, tx pgx.Tx, d Device, wake *DeviceScreenWake) (*DeviceScreenWakeReceipt, error) {
	if wake == nil {
		return nil, nil
	}
	var revision int64
	var desired, previous []byte
	if err := tx.QueryRow(ctx, `SELECT desired_revision,desired_config,
		COALESCE(reported_config->'screen_wake','null'::jsonb)
		FROM device_twin WHERE device_id=$1 AND tenant_id=$2 FOR UPDATE`, d.ID, d.TenantID).Scan(&revision, &desired, &previous); err != nil {
		return nil, err
	}
	var receipt DeviceScreenWakeReceipt
	if json.Unmarshal(previous, &receipt) == nil && receipt.ID == wake.ID {
		if receipt.Revision != wake.Revision {
			return nil, fail(409, "SCREEN_WAKE_CONFLICT", "唤醒请求已变化")
		}
		return &receipt, nil
	}
	receipt = DeviceScreenWakeReceipt{DeviceScreenWake: *wake, Result: "superseded"}
	if revision != wake.Revision {
		return &receipt, nil
	}
	var config map[string]json.RawMessage
	if err := json.Unmarshal(desired, &config); err != nil {
		return nil, err
	}
	var power struct {
		Mode string `json:"mode"`
	}
	if err := json.Unmarshal(config["power"], &power); err != nil || (power.Mode != "standby" && power.Mode != "active") {
		return &receipt, nil
	}
	if power.Mode == "standby" {
		if _, err := tx.Exec(ctx, `UPDATE device_twin
			SET desired_config=jsonb_set(desired_config,'{power}','{"mode":"active"}'::jsonb),
			desired_revision=desired_revision+1,updated_at=now()
			WHERE device_id=$1 AND tenant_id=$2`, d.ID, d.TenantID); err != nil {
			return nil, err
		}
	}
	receipt.Result = "applied"
	return &receipt, nil
}

func (s *Service) DeviceControlSync(ctx context.Context, d Device, in DeviceControlReport) (map[string]any, error) {
	if !deviceAllowed(d) {
		return nil, errAccess
	}
	if err := validateControlReport(in); err != nil {
		return nil, err
	}
	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return nil, err
	}
	defer tx.Rollback(ctx)
	wakeReceipt, err := reconcileScreenWake(ctx, tx, d, in.ScreenWake)
	if err != nil {
		return nil, err
	}
	// Revision zero means the device has not applied cloud configuration yet.
	// Report hardware readings, never copy desired values into reported_config.
	values := map[string]any{"volume": map[string]any{"speaker": in.Speaker},
		"network": map[string]any{"type": "wifi", "rssi": in.RSSI}}
	// Older firmware omits the field; omission must not claim a name was applied.
	if in.DisplayName != nil {
		values["identity"] = map[string]any{"display_name": *in.DisplayName}
	}
	if in.Power != nil {
		values["power"] = in.Power
	}
	if wakeReceipt != nil {
		values["screen_wake"] = wakeReceipt
	}
	reported, _ := json.Marshal(values)
	tag, err := tx.Exec(ctx, `UPDATE device_twin SET firmware_version=$3,
		reported_config=reported_config || $4::jsonb,
		reported_revision=NULLIF($5,0),
		last_reported_at=now(),updated_at=now()
		WHERE device_id=$1 AND tenant_id=$2 AND $5<=desired_revision
		AND ($5=0 OR reported_revision IS NULL OR $5>=reported_revision)`, d.ID, d.TenantID, in.Firmware, reported, in.Revision)
	if err != nil {
		return nil, err
	}
	if tag.RowsAffected() != 1 {
		return nil, fail(409, "CONFIG_REVISION_CONFLICT", "配置版本已变化，请重新同步")
	}
	if err := tx.Commit(ctx); err != nil {
		return nil, err
	}
	repo := device.NewRepository(s.pool)
	config, err := repo.GetConfiguration(ctx, controlIdentity(d))
	if err != nil {
		return nil, err
	}
	items := []device.Command{}
	if !in.Busy {
		items, err = repo.PullCommands(ctx, controlIdentity(d), 1)
		if err != nil {
			return nil, err
		}
	}
	out := map[string]any{"configuration": config, "commands": items}
	if wakeReceipt != nil {
		out["screen_wake"] = wakeReceipt
	}
	return out, nil
}

type DeviceControlAck struct {
	ID     string         `json:"command_id"`
	Status string         `json:"status"`
	Result map[string]any `json:"result_summary"`
}

func validateControlAck(in DeviceControlAck) error {
	if _, err := uuid.Parse(in.ID); err != nil {
		return fail(400, "INVALID_COMMAND_ACK", "命令编号不正确")
	}
	if in.Status != "ACKNOWLEDGED" && in.Status != "SUCCEEDED" && in.Status != "FAILED" {
		return fail(400, "INVALID_COMMAND_ACK", "命令状态不正确")
	}
	raw, err := json.Marshal(in.Result)
	if err != nil || len(raw) > 4096 {
		return fail(400, "INVALID_COMMAND_ACK", "诊断结果过大或格式不正确")
	}
	return nil
}

func (s *Service) DeviceControlAcknowledge(ctx context.Context, d Device, in DeviceControlAck) (map[string]any, error) {
	if !deviceAllowed(d) {
		return nil, errAccess
	}
	if err := validateControlAck(in); err != nil {
		return nil, err
	}
	if in.Result == nil {
		in.Result = map[string]any{}
	}
	_, err := device.NewRepository(s.pool).AcknowledgeCommand(ctx, controlIdentity(d), in.ID,
		device.CommandAcknowledgement{Status: in.Status, ResultSummary: in.Result})
	if err != nil {
		// A missing, foreign, expired, or terminal command cannot gain authority.
		if !errors.Is(err, pgx.ErrNoRows) {
			return nil, err
		}
		return nil, fail(409, "DEVICE_COMMAND_STATE_CONFLICT", "命令不存在、已过期或状态已变化")
	}
	return map[string]any{"status": "ok"}, nil
}