[#7] Content Utilities

lib/content.test.ts

@@ -0,0 +1,103 @@
+import { describe, expect, it } from "vitest";
+import {
+  hashContent,
+  validateContentLength,
+  MIN_CONTENT_LENGTH,
+  MAX_CONTENT_LENGTH,
+} from "./content";
+
+// ---------------------------------------------------------------------------
+// hashContent
+// ---------------------------------------------------------------------------
+
+describe("hashContent", () => {
+  it("returns a 0x-prefixed 66-char hex string", () => {
+    const hash = hashContent("hello");
+    expect(hash).toMatch(/^0x[0-9a-f]{64}$/);
+  });
+
+  it("is deterministic", () => {
+    const a = hashContent("test content");
+    const b = hashContent("test content");
+    expect(a).toBe(b);
+  });
+
+  it("produces different hashes for different content", () => {
+    expect(hashContent("aaa")).not.toBe(hashContent("bbb"));
+  });
+
+  it("handles Korean text", () => {
+    const hash = hashContent("안녕하세요 세계");
+    expect(hash).toMatch(/^0x[0-9a-f]{64}$/);
+  });
+
+  it("handles emoji", () => {
+    const hash = hashContent("🔥🚀✨");
+    expect(hash).toMatch(/^0x[0-9a-f]{64}$/);
+  });
+});
+
+// ---------------------------------------------------------------------------
+// validateContentLength
+// ---------------------------------------------------------------------------
+
+describe("validateContentLength", () => {
+  const makeString = (char: string, count: number) =>
+    Array.from({ length: count }, () => char).join("");
+
+  it("rejects content shorter than 500 characters", () => {
+    const result = validateContentLength(makeString("a", 499));
+    expect(result.valid).toBe(false);
+    expect(result.charCount).toBe(499);
+  });
+
+  it("accepts content at exactly 500 characters", () => {
+    const result = validateContentLength(makeString("a", 500));
+    expect(result.valid).toBe(true);
+    expect(result.charCount).toBe(500);
+  });
+
+  it("accepts content at exactly 10,000 characters", () => {
+    const result = validateContentLength(makeString("a", 10_000));
+    expect(result.valid).toBe(true);
+    expect(result.charCount).toBe(10_000);
+  });
+
+  it("rejects content longer than 10,000 characters", () => {
+    const result = validateContentLength(makeString("a", 10_001));
+    expect(result.valid).toBe(false);
+    expect(result.charCount).toBe(10_001);
+  });
+
+  // Unicode correctness — Korean syllables are single characters
+  it("counts Korean syllables as single characters", () => {
+    // 가 = U+AC00, 3 bytes in UTF-8 but 1 character
+    const korean = makeString("가", 500);
+    const result = validateContentLength(korean);
+    expect(result.charCount).toBe(500);
+    expect(result.valid).toBe(true);
+  });
+
+  // Emoji (many are multi-byte or surrogate pairs)
+  it("counts emoji as single characters", () => {
+    // 🔥 = U+1F525, 4 bytes in UTF-8, 2 UTF-16 code units, but 1 character
+    const emoji = makeString("🔥", 500);
+    const result = validateContentLength(emoji);
+    expect(result.charCount).toBe(500);
+    expect(result.valid).toBe(true);
+  });
+
+  // Mixed content
+  it("correctly counts mixed Korean, emoji, and ASCII", () => {
+    // 3 Korean + 2 emoji + 5 ASCII = 10 characters
+    const mixed = "안녕하🔥🚀hello";
+    const result = validateContentLength(mixed);
+    expect(result.charCount).toBe(10);
+    expect(result.valid).toBe(false); // under 500
+  });
+
+  it("exports MIN and MAX constants", () => {
+    expect(MIN_CONTENT_LENGTH).toBe(500);
+    expect(MAX_CONTENT_LENGTH).toBe(10_000);
+  });
+});

lib/content.ts

@@ -0,0 +1,38 @@
+import { keccak256, toHex } from "viem";
+
+/** Minimum content length in Unicode characters. */
+export const MIN_CONTENT_LENGTH = 500;
+
+/** Maximum content length in Unicode characters. */
+export const MAX_CONTENT_LENGTH = 10_000;
+
+/**
+ * Compute keccak256 hash of content, matching the onchain contentHash
+ * stored in PlotChained events.
+ *
+ * Uses UTF-8 encoding — same as `keccak256(toBytes(content))` in viem
+ * and `keccak256(abi.encodePacked(content))` in Solidity.
+ */
+export function hashContent(content: string): `0x${string}` {
+  return keccak256(toHex(content));
+}
+
+/**
+ * Validate content length using Unicode-aware character counting.
+ *
+ * Uses `[...str].length` (iterator-based) to correctly count characters
+ * like Korean syllables and emoji as single characters regardless of
+ * their UTF-8 byte length.
+ *
+ * Range: 500–10,000 characters (proposal §4.1).
+ */
+export function validateContentLength(content: string): {
+  valid: boolean;
+  charCount: number;
+} {
+  const charCount = [...content].length;
+  return {
+    valid: charCount >= MIN_CONTENT_LENGTH && charCount <= MAX_CONTENT_LENGTH,
+    charCount,
+  };
+}