import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from "fs";
import { tmpdir } from "os";
import { join } from "path";
import { afterEach, describe, expect, it } from "vitest";
import {
	appendSuffix,
	expandSkill,
	formatBlock,
	readSkillBody,
	type SkillBlockMeta,
} from "../src/expand";

const tempDirs: string[] = [];

afterEach(() => {
	for (const dir of tempDirs.splice(0)) {
		rmSync(dir, { recursive: true, force: true });
	}
});

function writeSkillMd(dir: string, name: string, content: string): SkillBlockMeta {
	const baseDir = join(dir, name);
	const filePath = join(baseDir, "SKILL.md");
	mkdirSync(baseDir, { recursive: true });
	writeFileSync(filePath, content, "utf-8");
	return { name, filePath, baseDir };
}

describe("readSkillBody", () => {
	it("strips YAML frontmatter and trims body", () => {
		const dir = mkdtempSync(join(tmpdir(), "pi-skill-reinject-expand-"));
		tempDirs.push(dir);
		const meta = writeSkillMd(
			dir,
			"demo-skill",
			`---
name: demo-skill
description: Demo
---

# Instructions

Do the thing.
`,
		);

		expect(readSkillBody(meta.filePath)).toBe("# Instructions\n\nDo the thing.");
	});

	it("returns trimmed body when frontmatter is absent", () => {
		const dir = mkdtempSync(join(tmpdir(), "pi-skill-reinject-expand-"));
		tempDirs.push(dir);
		const meta = writeSkillMd(dir, "plain", "  hello world  \n");

		expect(readSkillBody(meta.filePath)).toBe("hello world");
	});
});

describe("formatBlock", () => {
	it("embeds name, location, baseDir, and body", () => {
		const meta: SkillBlockMeta = {
			name: "brave-search",
			filePath: "/home/user/.pi/skills/brave-search/SKILL.md",
			baseDir: "/home/user/.pi/skills/brave-search",
		};

		expect(formatBlock(meta, "Search the web.")).toBe(
			`<skill name="brave-search" location="/home/user/.pi/skills/brave-search/SKILL.md">
References are relative to /home/user/.pi/skills/brave-search.

Search the web.
</skill>`,
		);
	});
});

describe("appendSuffix", () => {
	it("appends suffix after a blank line", () => {
		const block = "<skill>body</skill>";
		expect(appendSuffix(block, "[skill-reinject] note")).toBe(
			`${block}\n\n[skill-reinject] note`,
		);
	});

	it("returns block unchanged for empty or whitespace suffix", () => {
		const block = "<skill>body</skill>";
		expect(appendSuffix(block, undefined)).toBe(block);
		expect(appendSuffix(block, "   ")).toBe(block);
	});
});

describe("expandSkill", () => {
	it("produces full injectable text with optional suffix", () => {
		const dir = mkdtempSync(join(tmpdir(), "pi-skill-reinject-expand-"));
		tempDirs.push(dir);
		const meta = writeSkillMd(
			dir,
			"pdf-tools",
			`---
name: pdf-tools
---

Extract pages from PDFs.
`,
		);

		const withoutSuffix = expandSkill(meta);
		expect(withoutSuffix).toContain('name="pdf-tools"');
		expect(withoutSuffix).toContain(`location="${meta.filePath}"`);
		expect(withoutSuffix).toContain(`References are relative to ${meta.baseDir}.`);
		expect(withoutSuffix).toContain("Extract pages from PDFs.");

		expect(expandSkill(meta, "[skill-reinject] Re-applied.")).toBe(
			`${withoutSuffix}\n\n[skill-reinject] Re-applied.`,
		);
	});
});