oc-lib/tools/api.go

package tools

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

	"cloud.o-forge.io/core/oc-lib/config"
	"cloud.o-forge.io/core/oc-lib/dbs/mongo"
	beego "github.com/beego/beego/v2/server/web"
)

/*
* API is the Health Check API
* it defines the health check methods
 */
var UncatchedError = []error{} // Singleton instance of the api 500 error cache

type State int

// State is an enum that defines the state of the API
const (
	ALIVE                State = iota
	REDUCED_SERVICE            // occurs when some services are down
	UNPROCESSABLE_ENTITY       // occurs when the database is up but the collections are not
	DB_FALLOUT                 // occurs when the database is down
	TEAPOT                     // well some things boils in here, i'm probably a teapot, occurs when uncatched errors are present (it's fun)
	DEAD                       // occurs when the peer is dead
)

// EnumIndex returns the index of the enum
func (s State) EnumIndex() int {
	return int(s)
}

// ToState returns the state from a string
func ToState(str string) State {
	for _, s := range []State{ALIVE, REDUCED_SERVICE, UNPROCESSABLE_ENTITY, DB_FALLOUT, TEAPOT, DEAD} {
		if s.String() == str {
			return s
		}
	}
	return DEAD
}

// String returns the string of the enum
func (s State) String() string {
	return [...]string{"alive", "reduced service", "unprocessable entity", "database fallout",
		"some things boils in here, i'm probably a teapot", "dead"}[s]
}

type API struct{}

func (a *API) Discovered() {
	respondToDiscovery := func(m map[string]interface{}) {
		if len(m) == 0 {
			a.SubscribeRouter()
		}
	}
	a.ListenRouter(respondToDiscovery)
	a.SubscribeRouter()
}

// GetState returns the state of the API
func (a *API) GetState() (State, int, error) {
	// Check if the database is up
	err := mongo.MONGOService.TestDB(config.GetConfig())
	if err != nil {
		return DB_FALLOUT, 200, err // If the database is not up, return database fallout
	}
	err = mongo.MONGOService.TestCollections(config.GetConfig(), []string{}) // Check if the collections are up
	if err != nil {
		return UNPROCESSABLE_ENTITY, 200, err // If the collections are not up, return unprocessable entity
	}
	if len(UncatchedError) > 0 { // If there are uncatched errors, return teapot
		errStr := ""
		for _, e := range UncatchedError {
			errStr += e.Error() + "\n"
		}
		return TEAPOT, 200, errors.New(errStr)
	}
	return ALIVE, 200, nil // If everything is up, return alive
}

func (a *API) ListenRouter(exec func(msg map[string]interface{})) {
	go NewNATSCaller().ListenNats(DISCOVERY.GenerateKey("api"), exec)
}

func (a *API) SubscribeRouter(infos []*beego.ControllerInfo) {
	nats := NewNATSCaller()
	discovery := map[string]interface{}{}
	for _, info := range infos {
		methods := []string{}
		for k := range info.GetMethod() {
			methods = append(methods, k)
		}
		path := strings.ReplaceAll(info.GetPattern(), "/oc", "/"+strings.ReplaceAll(config.GetAppName(), "oc-", ""))
		discovery[path] = methods
	}
	nats.SetNATSPub("api", DISCOVERY, discovery)
}

// CheckRemotePeer checks the state of a remote peer
func (a *API) CheckRemotePeer(url string) (State, map[string]int) {
	// Check if the database is up
	caller := NewHTTPCaller(map[DataType]map[METHOD]string{}) // Create a new http caller
	var resp APIStatusResponse
	b, err := caller.CallPost(url, "", map[string]interface{}{}) // Call the status endpoint of the peer
	if err != nil {
		return DEAD, map[string]int{} // If the peer is not reachable, return dead
	}
	json.Unmarshal(b, &resp)
	if resp.Data == nil { // If the response is empty, return dead
		return DEAD, map[string]int{}
	}
	new := map[string]int{}
	for k, v := range resp.Data.Services { // Return the services states of the peer
		new[k] = ToState(v).EnumIndex()
	}
	return ToState(resp.Data.State), new // Return the state of the peer & its services states
}

// CheckRemoteAPIs checks the state of remote APIs from your proper OC
func (a *API) CheckRemoteAPIs(apis []DataType) (State, map[string]string, error) {
	// Check if the database is up
	new := map[string]string{}
	caller := NewHTTPCaller(map[DataType]map[METHOD]string{}) // Create a new http caller
	code := 0
	e := ""
	state := ALIVE
	reachable := false
	for _, api := range apis { // Check the state of each remote API in the list
		var resp APIStatusResponse
		b, err := caller.CallGet(api.API()+":8080", "/oc/version/status") // Call the status endpoint of the remote API (standard OC status endpoint)
		if err != nil {
			state = REDUCED_SERVICE // If a remote API is not reachable, return reduced service
			continue
		}
		json.Unmarshal(b, &resp)
		if resp.Data == nil { //
			state = REDUCED_SERVICE // If the response is empty, return reduced service
			continue
		}
		new[api.String()] = resp.Data.State
		if resp.Data.Code > code {
			code = resp.Data.Code
			e += resp.Error
		}
		reachable = true // If the remote API is reachable, set reachable to true cause we are not dead
	}
	if !reachable {
		state = DEAD // If no remote API is reachable, return dead, nobody is alive
	}
	if code > 0 {
		state = REDUCED_SERVICE
	}
	return state, new, nil
}

/* APIStatusResponse is the response of the API status */
type APIStatusResponse struct {
	Data  *APIStatus `json:"data"`
	Error string     `json:"error"`
}

/*
* APIStatus is the status of the API
* it defines the state of the API
* Code is the status code, where 0 is ALIVE, 1 is REDUCED_SERVICE, 2 is UNPROCESSABLE_ENTITY, 3 is DB_FALLOUT, 4 is TEAPOT, 5 is DEAD
 */
type APIStatus struct {
	Code     int               `json:"code"`     // Code is the status code, where 0 is ALIVE, 1 is REDUCED_SERVICE, 2 is UNPROCESSABLE_ENTITY, 3 is DB_FALLOUT, 4 is TEAPOT, 5 is DEAD
	State    string            `json:"state"`    // State is the state of the API (status shows as a string) (alive, reduced service, unprocessable entity, database fallout, some things boils in here, i'm probably a teapot, dead)
	Services map[string]string `json:"services"` // Services is the state of the services of the API (status shows as a string) (alive, reduced service, unprocessable entity, database fallout, some things boils in here, i'm probably a teapot, dead)
}