Feat/labs eve realm and package

examples/gno.land/p/eve/README.md

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+WIP
+--- 
+
+What's left to get to 'final' version of eve framework
+
+### requirements
+
+A user can publish an item as a revision or update where the old CID is replaced with a new one.
+Old cid can be removed or kept as a reference.
+
+Gno.land visitors choose to view older revisions. (by traversing parent links)
+
+Other gno realms may embed path to /r/eve/home/?cid=... to show specific revisions.
+
+Page view has common footer menu that links to metadata and version info.
+
+
+As a user I can see the Object Registry (index at /r/lab/home?glyph=OfficeHours)
+Each registered object links out to its own realm (officehours at /r/labs/OfficeHours)
+
+Users can update the preferred view of an object if they are the original author.
+
+FUTURE: without using cur realm (realm crossing) - we can still build an immutable oracle.
+This is an append only fashion that does not allow permissions, only that each new object has a unique CID
+
+The Event Stream of (Glyph, URL, CID) is an immutable log of all objects ever created.
+
+### Metadata
+
+A design principle from gno.land: A realm SHOULD always resemble gno.land/r/ view.
+i.e. a fork on another realm should ideally use same markdown renderer and support same metadata.
+
+The metadata for each page SHOULD be linked from each eve.PageTemplate view.
+
+Every object is required to have a CID, JsonLD{ name, description }, and committer/author.
+Every object MAY have additional metadata such as tags, categories, license, etc.
+
+### Versioning
+
+Every object may have a link to the previous version.
+An object MAY have multiple parents (merging branches).
+
+### QueryParameters as Serializable State
+
+A Projectable Object accepts path as a 'Probe' to determine what to render.
+A Probe is a 'path' that is serializable state that can be shared via URL query parameters.
+
+A complete view of an object is only inspectable by probing the inner dimensions of the object.
+This means that a user can share a link to a specific view of an object. 
+
+### Identity and Types
+
+Objects have metadata in the shape of JsonLD.
+Each Object is identified by its CID.
+
+Unless specified otherwise, an object is assumed to be of type "Thing" (schema.org/Thing).
+An object MAY have multiple types (schema.org allows this).
+
+## Existing Projectable Objects
+
+### eve.Flyer Object
+A Flyer is a Projectable Object that has a title, description, image, and link.
+
+### Event Projectable Object
+"Event" (schema.org/Event).
+An Event object has properties such as startDate, endDate, location, performer, etc.
+
+### Calendar Event Projectable Object
+A Calendar Event is a Projectable Object that can render different views based on the Probe.
+
+### Office Hours Event
+A specialized event formatted as ICS, contains a recurrence rule (RRULE).
+
+### Probes
+
+The Render() function accepts a Probe that is a path that is serializable state that can be shared via URL query parameters.
+
+Object + Probe => RenderedView
+
+### Future Work
+- Permissions and Access Control Lists (ACLs) 
+- Standard views of common object types (e.g., Articles, Projects, Profiles)

examples/gno.land/p/eve/component/cid.gno

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+package component
+
+import (
+	"crypto/sha256"
+	"encoding/base32"
+	"encoding/hex"
+	"strings"
+	"time"
+)
+
+func HashStrings(elements ...string) string {
+	combined := ""
+	for _, e := range elements {
+		combined += e
+	}
+	return HashString(combined)
+}
+
+func HashString(s interface{}) string {
+	if s == nil {
+		return ""
+	}
+	if str, ok := s.(string); ok {
+		s = str
+	} else if t, ok := s.(time.Time); ok {
+		s = t.Format(time.RFC3339)
+	} else if es, ok := s.(EventStatus); ok {
+		s = string(es)
+	} else if eam, ok := s.(EventAttendanceMode); ok {
+		s = string(eam)
+	} else {
+		panic("type not supported for hashing: ")
+	}
+
+	hash := sha256.Sum256([]byte(s.(string)))
+	return hex.EncodeToString(hash[:])
+}
+
+// ShaToCid converts a hex-encoded SHA-256 digest into a CIDv1 (base32, multibase "b").
+// Layout: <0x01 version><0x55 codec=raw><0x12 mh=sha2-256><0x20 len=32><digest>
+func ShaToCid(sha string) string {
+	sha = strings.TrimSpace(sha)
+
+	// Decode hex digest (must be 32 bytes for sha2-256)
+	digest, err := hex.DecodeString(sha)
+	if err != nil || len(digest) != 32 {
+		panic("invalid sha256 digest")
+	}
+
+	// Assemble CIDv1 bytes
+	// 0x01 = version 1
+	// 0x55 = multicodec "raw"
+	// 0x12 = multihash code for sha2-256, 0x20 = digest length (32)
+	buf := make([]byte, 0, 1+1+2+32)
+	buf = append(buf, 0x01, 0x55, 0x12, 0x20)
+	buf = append(buf, digest...)
+
+	// Base32 (RFC 4648), no padding, lowercase, with multibase 'b' prefix
+	enc := base32.StdEncoding.WithPadding(base32.NoPadding)
+	return "b" + strings.ToLower(enc.EncodeToString(buf))
+}
+
+// IsCIDv1 checks if the given string is a valid CIDv1 in base32 format.
+func IsCIDv1(s string) bool {
+	if len(s) != 59 {
+		return false
+	}
+	for _, r := range s {
+		if !('a' <= r && r <= 'z' || '2' <= r && r <= '7') { // base32 alphabet
+			return false
+		}
+	}
+	if !strings.HasPrefix(s, "bafkrei") {
+		return false
+	}
+	return true
+}
+
+func MustCIDv1(label, s string) {
+	if !IsCIDv1(s) {
+		panic("invalid " + label + ": not a CIDv1")
+	}
+}