spaceapid/util/util.go
2024-05-26 20:52:15 +02:00

120 lines
3.6 KiB
Go

package util
import (
"encoding/json"
"errors"
"log"
"os"
"path"
"git.hamburg.ccc.de/ccchh/spaceapid/types"
)
const (
savedStateJSONPath = "/var/lib/spaceapid/spaceapid-state.json"
)
// MergeOldState merges a given SpaceAPIResponse with the state saved at the time of last program exit and then deletes
// the file containing the old state.
func MergeOldState(response *types.SpaceAPIResponseV14) {
var (
err error
oldState []byte
persistedState types.PersistentStateV14
)
log.Println("Merging old state from", savedStateJSONPath, "...")
// Check if state.json is present
_, err = os.Stat(savedStateJSONPath)
if err != nil {
log.Println("Old state json not accessible at", savedStateJSONPath, ", skipping merge... error:", err)
if errors.Is(err, os.ErrNotExist) {
return
}
goto removeOld
}
// Read file and load persisted state
oldState, err = os.ReadFile(savedStateJSONPath)
if err != nil {
log.Println("Error reading old state from", savedStateJSONPath, ", skipping merge... error:", err)
goto removeOld
}
err = json.Unmarshal(oldState, &persistedState)
if err != nil {
log.Println(savedStateJSONPath, "doesn't seem to contain valid data... error:", err)
goto removeOld
}
// Merge state
response.State = persistedState.State
// Merge sensors
for key, environmentSensors := range persistedState.Sensors {
for _, sensor := range environmentSensors {
// Order or amount of sensors might have changed, so check sensors already present in response
// and then look for matching values in persisted state
for i := range response.Sensors[key] {
if rs := &response.Sensors[key][i]; rs.Location == sensor.Location && rs.Name == sensor.Name {
rs.Value = sensor.Value
rs.LastChange = sensor.LastChange
}
}
}
}
// Delete old state json
removeOld:
err = os.RemoveAll(savedStateJSONPath)
if err != nil {
log.Println("Failed to remove", savedStateJSONPath, ", continuing... error:", err)
}
}
func SaveCurrentState(response types.SpaceAPIResponseV14) {
// Create state directory if not present
err := os.MkdirAll(path.Dir(savedStateJSONPath), 0750)
if err != nil {
log.Fatalln("Failed creating", savedStateJSONPath, ", aborting... error:", err)
}
// Open persistent state file
file, err := os.OpenFile(savedStateJSONPath, os.O_WRONLY|os.O_CREATE, 0644)
if err != nil {
log.Fatalln("Failed opening", savedStateJSONPath, "while trying to save current state... error:", err)
}
defer file.Close()
// Create persistent state
persistentStateV14 := types.PersistentStateV14{
State: struct {
Open bool `json:"open"`
LastChange int64 `json:"lastchange"`
}{Open: response.State.Open, LastChange: response.State.LastChange},
}
// Save sensor state
persistentStateV14.Sensors = make(map[string][]types.PersistentEnvironmentSensor)
for key, environmentSensors := range response.Sensors {
persistentStateV14.Sensors[key] = make([]types.PersistentEnvironmentSensor, len(environmentSensors))
for i, sensor := range environmentSensors {
persistentStateV14.Sensors[key][i].Value = sensor.Value
persistentStateV14.Sensors[key][i].Location = sensor.Location
persistentStateV14.Sensors[key][i].Name = sensor.Name
persistentStateV14.Sensors[key][i].LastChange = sensor.LastChange
}
}
// Serialize persistent state
marshal, err := json.MarshalIndent(persistentStateV14, "", "\t")
if err != nil {
log.Fatalln("Failed serializing persistent state... error:", err)
}
// Write to file
_, err = file.Write(marshal)
if err != nil {
log.Fatalln("Failed writing persistent state to file", file.Name(), "... error:", err)
}
}