IliaDenisov
105 lines
3.6 KiB
Go
105 lines
3.6 KiB
Go
package connector
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import (
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"crypto/sha256"
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"encoding/hex"
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"encoding/json"
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"fmt"
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"galaxy/model/client"
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"galaxy/model/report"
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)
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// Connector is a main interface to provide connectivity with app's server.
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type Connector interface {
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UIConnector
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// CheckConnection is called asynchronously every 5 seconds and tests is connection available with a specific backend server endpoint.
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// There is guaranteed jittered backoff with caps 5s -> 15s -> 30s -> 60s when no connection is available.
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CheckConnection() bool
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// CheckVersion is called asynchronously every 30 minutes and receives from backend server information about currently available app versions.
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CheckVersion() ([]VersionInfo, error)
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// DownloadVersion asynchronously retrieves from a specific string URL a binary artifact from backend server.
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DownloadVersion(string) ([]byte, error)
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}
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// UIConnector contains only funcs are needed for the client app to be functional.
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type UIConnector interface {
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// FetchReport asynchronously requests from backend server a [report.Report] for a given [model.GameID] and turn number.
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// Passed callback func will will accept non-nil error in case of I/O or decoding errors occuried,
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// otherwise callback func accepts loaded [report.Report].
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FetchReport(client.GameID, uint, func(report.Report, error))
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}
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type VersionInfo struct {
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OS string `json:"os"` // Operating System name (unix, darwin, windows, etc.)
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Version string `json:"version"` // Semver format: X.Y.Z
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URL string `json:"url"` // Artifact download URL for this version
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Checksum SHA256Digest `json:"sha256"` // Base64 SHA-256 checksum for artifact binary data
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}
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// SHA256Digest represents a SHA-256 digest in raw binary form.
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//
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// Internally it stores the exact 32-byte digest.
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// In JSON it is encoded as a lowercase hexadecimal string of 64 characters.
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type SHA256Digest [32]byte
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// NewSHA256Digest calculates SHA-256 for the provided byte slice
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// and returns the digest as SHA256Digest.
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//
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// The function does not modify the input data.
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func NewSHA256Digest(data []byte) SHA256Digest {
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sum := sha256.Sum256(data)
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return SHA256Digest(sum)
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}
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// String returns the lowercase hexadecimal representation
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// of the digest.
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//
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// The returned string always contains exactly 64 characters.
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func (d SHA256Digest) String() string {
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return hex.EncodeToString(d[:])
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}
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// MarshalJSON encodes the digest as a JSON string containing
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// the lowercase hexadecimal SHA-256 value.
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//
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// Example JSON value:
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//
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// "b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9"
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func (d SHA256Digest) MarshalJSON() ([]byte, error) {
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return json.Marshal(d.String())
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}
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// UnmarshalJSON decodes a JSON string containing a lowercase or uppercase
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// hexadecimal SHA-256 value into the digest.
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//
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// The input must be a JSON string with exactly 64 hexadecimal characters.
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func (d *SHA256Digest) UnmarshalJSON(data []byte) error {
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var s string
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if err := json.Unmarshal(data, &s); err != nil {
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return fmt.Errorf("sha256 digest must be a JSON string: %w", err)
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}
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if len(s) != hex.EncodedLen(len(d)) {
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return fmt.Errorf("invalid SHA-256 hex length: got %d, want %d", len(s), hex.EncodedLen(len(d)))
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}
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decoded, err := hex.DecodeString(s)
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if err != nil {
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return fmt.Errorf("invalid SHA-256 hex value: %w", err)
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}
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copy(d[:], decoded)
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return nil
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}
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// Equal returns true when both digests are identical.
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//
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// Since SHA256Digest is based on a fixed-size array, direct value comparison
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// is efficient and idiomatic for non-constant-time equality checks.
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func (d SHA256Digest) Equal(other SHA256Digest) bool {
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return d == other
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}
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