refactor: combine frontmatter fields and block, add tests

src/frontmatter/frontmatterBlock.ts

@@ -1,148 +0,0 @@
-/** 0-based line/column range in the document. */
-export type TextRange = {
-	startLine: number;
-	startCol: number;
-	endLine: number;
-	endCol: number;
-};
-
-export type FrontmatterBlock = {
-	/** YAML body between fences (no --- lines). */
-	yaml: string;
-	/** Line index of opening `---`. */
-	openLine: number;
-	/** Line index of closing `---`. */
-	closeLine: number;
-	/** Inclusive range covering the whole frontmatter including fences. */
-	range: TextRange;
-};
-
-/**
- * Extract YAML frontmatter fenced by `---` lines at the start of the file.
- * Returns null if there is no opening fence on line 0.
- */
-export function extractFrontmatterBlock(
-	content: string,
-): FrontmatterBlock | null {
-	const lines = content.split(/\r?\n/);
-	if (lines.length === 0 || lines[0].trim() !== "---") {
-		return null;
-	}
-
-	let closeLine = -1;
-	for (let i = 1; i < lines.length; i += 1) {
-		if (lines[i].trim() === "---") {
-			closeLine = i;
-			break;
-		}
-	}
-
-	if (closeLine < 0) {
-		return {
-			yaml: lines.slice(1).join("\n"),
-			openLine: 0,
-			closeLine: -1,
-			range: {
-				startLine: 0,
-				startCol: 0,
-				endLine: Math.max(0, lines.length - 1),
-				endCol: lines[lines.length - 1]?.length ?? 0,
-			},
-		};
-	}
-
-	const yamlLines = lines.slice(1, closeLine);
-	return {
-		yaml: yamlLines.join("\n"),
-		openLine: 0,
-		closeLine,
-		range: {
-			startLine: 0,
-			startCol: 0,
-			endLine: closeLine,
-			endCol: lines[closeLine].length,
-		},
-	};
-}
-
-/** Range of `key:` line value inside frontmatter, or full key line / whole FM. */
-export function findFieldRange(
-	content: string,
-	key: string,
-): TextRange | undefined {
-	const block = extractFrontmatterBlock(content);
-	if (!block || block.closeLine < 0) {
-		return block?.range;
-	}
-
-	const lines = content.split(/\r?\n/);
-	const keyPattern = new RegExp(`^(\\s*)(${escapeRegExp(key)})\\s*:\\s*(.*)$`);
-
-	for (let i = block.openLine + 1; i < block.closeLine; i += 1) {
-		const line = lines[i] ?? "";
-		const match = keyPattern.exec(line);
-		if (!match) continue;
-
-		const indent = match[1] ?? "";
-		const valueText = match[3] ?? "";
-		const colonIndex = line.indexOf(":", indent.length);
-		const afterColon = colonIndex + 1;
-		let valueCol = afterColon;
-		while (
-			valueCol < line.length &&
-			(line[valueCol] === " " || line[valueCol] === "\t")
-		) {
-			valueCol += 1;
-		}
-
-		if (valueText.length === 0) {
-			return {
-				startLine: i,
-				startCol: 0,
-				endLine: i,
-				endCol: line.length,
-			};
-		}
-
-		return {
-			startLine: i,
-			startCol: valueCol,
-			endLine: i,
-			endCol: line.length,
-		};
-	}
-
-	return undefined;
-}
-
-/** Full line range for a frontmatter key (key + value). */
-export function findFieldLineRange(
-	content: string,
-	key: string,
-): TextRange | undefined {
-	const block = extractFrontmatterBlock(content);
-	if (!block || block.closeLine < 0) {
-		return undefined;
-	}
-
-	const lines = content.split(/\r?\n/);
-	const keyPattern = new RegExp(`^\\s*${escapeRegExp(key)}\\s*:`);
-
-	for (let i = block.openLine + 1; i < block.closeLine; i += 1) {
-		const line = lines[i] ?? "";
-		if (keyPattern.test(line)) {
-			return {
-				startLine: i,
-				startCol: 0,
-				endLine: i,
-				endCol: line.length,
-			};
-		}
-	}
-
-	return undefined;
-}
-
-function escapeRegExp(value: string): string {
-	return value.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
-}

src/frontmatter/frontmatterFields.test.ts

@@ -1,5 +1,6 @@
 import { describe, expect, it } from "vitest";
 import {
+	extractFrontmatterBlock,
 	findFieldRange,
 	formatTagsYamlValue,
 	replaceFrontmatterField,
@@ -76,3 +77,55 @@ describe("setFrontmatterTags", () => {
 		expect(result.content).not.toContain("tags: [old]");
 	});
 });
+
+describe("extractFrontmatterBlock", () => {
+	it("extracts yaml from a valid block", () => {
+		const block = extractFrontmatterBlock(
+			"---\ntitle: Hello\nstatus: todo\n---\nbody",
+		);
+		expect(block).not.toBeNull();
+		expect(block!.yaml).toBe("title: Hello\nstatus: todo");
+		expect(block!.closeLine).toBe(3);
+	});
+
+	it("returns null when content does not start with ---", () => {
+		expect(extractFrontmatterBlock("no frontmatter")).toBeNull();
+		expect(extractFrontmatterBlock("")).toBeNull();
+	});
+
+	it("handles unclosed frontmatter with trailing newline", () => {
+		const block = extractFrontmatterBlock("---\ntitle: x\n");
+		expect(block).not.toBeNull();
+		expect(block!.closeLine).toBe(-1);
+		expect(block!.yaml).toBe("title: x\n");
+	});
+
+	it("handles unclosed frontmatter without trailing newline", () => {
+		const block = extractFrontmatterBlock("---\ntitle: x");
+		expect(block).not.toBeNull();
+		expect(block!.closeLine).toBe(-1);
+		expect(block!.yaml).toBe("title: x");
+	});
+
+	it("handles CRLF line endings (yaml is normalized to LF)", () => {
+		const block = extractFrontmatterBlock(
+			"---\r\ntitle: Hello\r\nstatus: todo\r\n---\r\nbody",
+		);
+		expect(block).not.toBeNull();
+		expect(block!.yaml).toBe("title: Hello\nstatus: todo");
+	});
+
+	it("handles --- with trailing whitespace", () => {
+		const block = extractFrontmatterBlock(
+			"---  \ntitle: Hello\n---  \nbody",
+		);
+		expect(block).not.toBeNull();
+		expect(block!.yaml).toBe("title: Hello");
+		expect(block!.closeLine).toBe(2);
+	});
+
+	it("only matches --- on the first line", () => {
+		const block = extractFrontmatterBlock("text\n---\ntitle: x\n---\n");
+		expect(block).toBeNull();
+	});
+});

src/frontmatter/frontmatterFields.ts

@@ -1,13 +1,138 @@
 import { yamlInlineScalar } from "@/utils/yamlScalar";
-import {
-	extractFrontmatterBlock,
-	findFieldLineRange,
-	findFieldRange,
-	type TextRange,
-} from "./frontmatterBlock";
 
-export { findFieldLineRange, findFieldRange };
-export type { TextRange };
+/** 0-based line/column range in the document. */
+export type TextRange = {
+	startLine: number;
+	startCol: number;
+	endLine: number;
+	endCol: number;
+};
+
+type FrontmatterBlock = {
+	yaml: string;
+	openLine: number;
+	closeLine: number;
+	range: TextRange;
+};
+
+function escapeRegExp(value: string): string {
+	return value.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
+}
+
+export function extractFrontmatterBlock(content: string): FrontmatterBlock | null {
+	const NOT_FOUND = -1;
+	const lines = content.split(/\r?\n/);
+	if (lines.length === 0 || lines[0].trim() !== "---") {
+		return null;
+	}
+
+	let closeLine = NOT_FOUND;
+	for (let i = 1; i < lines.length; i += 1) {
+		if (lines[i].trim() === "---") {
+			closeLine = i;
+			break;
+		}
+	}
+
+	if (closeLine === NOT_FOUND) {
+		return {
+			yaml: lines.slice(1).join("\n"),
+			openLine: 0,
+			closeLine: NOT_FOUND,
+			range: {
+				startLine: 0,
+				startCol: 0,
+				endLine: Math.max(0, lines.length - 1),
+				endCol: lines[lines.length - 1]?.length ?? 0,
+			},
+		};
+	}
+
+	const yamlLines = lines.slice(1, closeLine);
+	return {
+		yaml: yamlLines.join("\n"),
+		openLine: 0,
+		closeLine,
+		range: {
+			startLine: 0,
+			startCol: 0,
+			endLine: closeLine,
+			endCol: lines[closeLine].length,
+		},
+	};
+}
+
+export function findFieldRange(content: string, key: string): TextRange | undefined {
+	const block = extractFrontmatterBlock(content);
+	if (!block || block.closeLine < 0) {
+		return block?.range;
+	}
+
+	const lines = content.split(/\r?\n/);
+	const keyPattern = new RegExp(`^(\\s*)(${escapeRegExp(key)})\\s*:\\s*(.*)$`);
+
+	for (let i = block.openLine + 1; i < block.closeLine; i += 1) {
+		const line = lines[i] ?? "";
+		const match = keyPattern.exec(line);
+		if (!match) continue;
+
+		const [, indent, , valueText = ""] = match;
+		const colonIndex = line.indexOf(":", indent.length);
+		const afterColon = colonIndex + 1;
+		let valueCol = afterColon;
+		while (
+			valueCol < line.length &&
+			(line[valueCol] === " " || line[valueCol] === "\t")
+		) {
+			valueCol += 1;
+		}
+
+		if (valueText.length === 0) {
+			return {
+				startLine: i,
+				startCol: 0,
+				endLine: i,
+				endCol: line.length,
+			};
+		}
+
+		return {
+			startLine: i,
+			startCol: valueCol,
+			endLine: i,
+			endCol: line.length,
+		};
+	}
+
+	return undefined;
+}
+
+function findFieldLineRange(
+	content: string,
+	key: string,
+): TextRange | undefined {
+	const block = extractFrontmatterBlock(content);
+	if (!block || block.closeLine < 0) {
+		return undefined;
+	}
+
+	const lines = content.split(/\r?\n/);
+	const keyPattern = new RegExp(`^\\s*${escapeRegExp(key)}\\s*:`);
+
+	for (let i = block.openLine + 1; i < block.closeLine; i += 1) {
+		const line = lines[i] ?? "";
+		if (keyPattern.test(line)) {
+			return {
+				startLine: i,
+				startCol: 0,
+				endLine: i,
+				endCol: line.length,
+			};
+		}
+	}
+
+	return undefined;
+}
 
 export type ReplaceFrontmatterFieldResult =
 	| { ok: true; content: string; range: TextRange }

src/frontmatter/parseTaskTags.ts

@@ -1,5 +1,5 @@
 import * as yaml from "js-yaml";
-import { extractFrontmatterBlock } from "./frontmatterBlock";
+import { extractFrontmatterBlock } from "./frontmatterFields";
 
 /** Read current tags array from task file content (empty if missing/invalid). */
 export function parseTaskTags(content: string): string[] {

src/frontmatter/validateFrontmatter.ts

@@ -6,7 +6,7 @@ import {
 	extractFrontmatterBlock,
 	findFieldRange,
 	type TextRange,
-} from "./frontmatterBlock";
+} from "./frontmatterFields";
 
 export type FrontmatterIssueSeverity = "error" | "warning";