HODA/internal/apps/store.go

package apps

import (
	"cmp"
	"slices"
	"strings"
	"sync"
	"time"
)

// LocalSource is the store key for the host this instance runs on. Agents are
// stored under their URL.
const LocalSource = "local"

// HostStatus says whether a Docker host answered on the last attempt. LastOK
// is only sent while the host is unreachable, so the response stays the same
// (and its ETag stable) while nothing changes.
type HostStatus struct {
	Name   string     `json:"name"`
	OK     bool       `json:"ok"`
	LastOK *time.Time `json:"lastOk,omitempty"`
}

// Response is the body of GET /api/apps, on the primary and on agents.
type Response struct {
	Node   string       `json:"node"`
	Hosts  []HostStatus `json:"hosts"`
	Apps   []App        `json:"apps"`
	Issues []Issue      `json:"issues"`
}

type source struct {
	status HostStatus
	apps   []App
	issues []Issue
}

// Store holds the latest apps and label problems of each source: this host,
// then one per agent.
type Store struct {
	mu      sync.RWMutex
	sources map[string]*source
	now     func() time.Time
}

// NewStore returns an empty store.
func NewStore() *Store {
	return &Store{sources: map[string]*source{}, now: time.Now}
}

// SetApps records a successful read of a source.
func (s *Store) SetApps(key, host string, list []App, issues []Issue) {
	now := s.now()
	s.mu.Lock()
	defer s.mu.Unlock()
	s.sources[key] = &source{status: HostStatus{Name: host, OK: true, LastOK: &now}, apps: list, issues: issues}
}

// SetReported records an agent's own view of its host. An agent that can't
// reach its Docker still sends its last known apps and when it last could.
func (s *Store) SetReported(key string, status HostStatus, list []App, issues []Issue) {
	if status.OK {
		now := s.now()
		status.LastOK = &now
	}
	s.mu.Lock()
	defer s.mu.Unlock()
	s.sources[key] = &source{status: status, apps: list, issues: issues}
}

// SetError marks a source unreachable and keeps its last known apps.
func (s *Store) SetError(key, host string) {
	s.mu.Lock()
	defer s.mu.Unlock()
	src, ok := s.sources[key]
	if !ok {
		src = &source{status: HostStatus{Name: host}}
		s.sources[key] = src
	}
	src.status.OK = false
}

// Lookup finds an app by ID and the key of the source that reported it.
func (s *Store) Lookup(id string) (key string, app App, ok bool) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	for k, src := range s.sources {
		for _, a := range src.apps {
			if a.ID == id {
				return k, a, true
			}
		}
	}
	return "", App{}, false
}

// Snapshot returns every host's status, all apps in display order and all
// label problems. localIcon gives the icon URL of this host's apps; agents send
// their own. The caller fills in Node.
func (s *Store) Snapshot(localIcon func(id string) string) Response {
	s.mu.RLock()
	defer s.mu.RUnlock()
	resp := Response{Hosts: make([]HostStatus, 0, len(s.sources)), Apps: []App{}, Issues: []Issue{}}
	for key, src := range s.sources {
		status := src.status
		if status.OK {
			status.LastOK = nil
		}
		resp.Hosts = append(resp.Hosts, status)
		for _, a := range src.apps {
			if key == LocalSource && localIcon != nil {
				a.Icon = localIcon(a.ID)
			}
			resp.Apps = append(resp.Apps, a)
		}
		resp.Issues = append(resp.Issues, src.issues...)
	}
	slices.SortFunc(resp.Hosts, func(a, b HostStatus) int { return strings.Compare(a.Name, b.Name) })
	slices.SortFunc(resp.Apps, compareApps)
	slices.SortFunc(resp.Issues, func(a, b Issue) int {
		return cmp.Or(strings.Compare(a.Host, b.Host), strings.Compare(a.Container, b.Container), strings.Compare(a.Message, b.Message))
	})
	return resp
}

// compareApps orders by group, with apps that have none last, then the order
// label, then name.
func compareApps(a, b App) int {
	ungrouped := func(app App) int {
		if app.Group == DefaultGroup {
			return 1
		}
		return 0
	}
	return cmp.Or(
		cmp.Compare(ungrouped(a), ungrouped(b)),
		cmp.Compare(strings.ToLower(a.Group), strings.ToLower(b.Group)),
		cmp.Compare(a.Order, b.Order),
		cmp.Compare(strings.ToLower(a.Name), strings.ToLower(b.Name)),
		cmp.Compare(a.Host, b.Host),
		cmp.Compare(a.ID, b.ID),
	)
}