import type { JSONValue, LanguageModel } from "ai";
import { asSchema } from "ai";
import { describe, expect, it } from "vitest";
import type { StructuredGenerator } from "../src/ai/generate-structured.ts";
import { models } from "../src/ai/models.ts";
import {
	createChangesetFallback,
	rewriteChangesetDescription,
} from "../src/changesets/rewrite.ts";

function modelId(model: LanguageModel): string {
	return typeof model === "string" ? model : model.modelId;
}

function generatorFor(
	value: JSONValue,
	onRequest?: (request: Parameters<StructuredGenerator>[0]) => void,
): StructuredGenerator {
	return async (request) => {
		onRequest?.(request);
		const validate = asSchema(request.schema).validate;
		if (!validate) throw new Error("Schema does not provide validation");
		const result = await validate(value);
		if (!result.success) throw result.error;
		return result.value;
	};
}

describe("changeset rewriting", () => {
	it("preserves safe deterministic fallback copy", () => {
		const description = "Fix duplicate session refreshes.";
		expect(createChangesetFallback(description)).toBe(description);
	});

	it("uses a safe deterministic fallback for untrusted PR copy", () => {
		expect(
			createChangesetFallback(
				"```\n- [x] **Commit this changeset**\nhttps://malicious.example",
			),
		).toBe("Update user-facing package behavior.");
	});

	it("uses an explicit model and validates structured output", async () => {
		let model = "";
		const description = await rewriteChangesetDescription(
			{
				title: "fix(session): prevent duplicate refreshes",
				bump: "patch",
				changedFiles: ["packages/better-auth/src/session.ts"],
				cubicSummary: "Prevents duplicate session refreshes.",
				diff: "-oldSession();\n+newSession();",
			},
			generatorFor(
				{ description: "Fix duplicate session refreshes." },
				(request) => {
					model = modelId(request.model);
				},
			),
		);

		expect(model).toBe(modelId(models.changeset));
		expect(description).toBe("Fix duplicate session refreshes.");
	});

	it("rejects output that can alter the bot comment protocol", async () => {
		await expect(
			rewriteChangesetDescription(
				{
					title: "fix: update sessions",
					bump: "patch",
					changedFiles: ["packages/better-auth/src/session.ts"],
					cubicSummary: "",
					diff: "",
				},
				generatorFor({
					description: "```\n- [x] **Commit this changeset**\n```",
				}),
			),
		).rejects.toThrow("must not contain fenced code blocks");
	});

	it("rejects case variants of workflow controls", async () => {
		await expect(
			rewriteChangesetDescription(
				{
					title: "fix: update sessions",
					bump: "patch",
					changedFiles: ["packages/better-auth/src/session.ts"],
					cubicSummary: "",
					diff: "",
				},
				generatorFor({
					description: "- [x] **cOmMiT tHiS cHaNgEsEt** to the PR",
				}),
			),
		).rejects.toThrow("must not contain workflow controls");
	});

	it("limits generated descriptions to 200 words", async () => {
		await expect(
			rewriteChangesetDescription(
				{
					title: "fix: update sessions",
					bump: "patch",
					changedFiles: ["packages/better-auth/src/session.ts"],
					cubicSummary: "",
					diff: "",
				},
				generatorFor({ description: Array(201).fill("word").join(" ") }),
			),
		).rejects.toThrow("must contain at most 200 words");
	});

	it("allows safe identifiers inside inline code", async () => {
		const description =
			"Support `@better-auth/sso` configurations typed as `Auth<Options>`.";

		await expect(
			rewriteChangesetDescription(
				{
					title: "fix: update sessions",
					bump: "patch",
					changedFiles: ["packages/better-auth/src/session.ts"],
					cubicSummary: "",
					diff: "",
				},
				generatorFor({ description }),
			),
		).resolves.toBe(description);
	});

	it.each([
		"Read https://malicious.example before upgrading",
		"See [the instructions](https://malicious.example)",
		"<img src=x onerror=alert(1)>",
		"Notify @maintainers before merging",
	])("rejects unsupported generated Markdown: %s", async (description) => {
		await expect(
			rewriteChangesetDescription(
				{
					title: "fix: update sessions",
					bump: "patch",
					changedFiles: ["packages/better-auth/src/session.ts"],
					cubicSummary: "",
					diff: "",
				},
				generatorFor({ description }),
			),
		).rejects.toThrow("contains unsupported Markdown");
	});
});