import { type AssistantMessage, fauxAssistantMessage, fauxText, Type } from "@earendil-works/pi-ai";
import { CodemodeSandbox } from "@earendil-works/pi-codemode";
import { CODEMODE_SOURCE_GRAMMAR } from "@earendil-works/pi-codemode/source";
import { defineTool, MemoryStorage, type ToolRegistration } from "@earendil-works/pi-durable";
import { describe, expect, it } from "vitest";
import { createCodemodeExtension } from "../src/codemode/codemode.ts";
import { type CodemodeNamespace, codemodeDescription, codemodeSection } from "../src/codemode/describe.ts";
import { allEntries, chatSetup, openChat } from "./chat-support.ts";
import { context } from "./session-support.ts";

function tool(name: string, description: string, extra: Partial<ToolRegistration> = {}): ToolRegistration {
	return defineTool({
		name,
		description,
		parameters: Type.Object({ path: Type.String({ description: "File path" }) }),
		execute: async () => ({ output: [] }),
		...extra,
	});
}

const GITHUB: CodemodeNamespace = { name: "github", description: "GitHub MCP server", prefix: "mcp__github__" };

describe("code mode description and section", () => {
	it("keeps the tool description the same for every conversation", () => {
		const text = codemodeDescription(false);
		expect(text).toContain("`await tools.<name>({ ...args })`");
		expect(text).toContain("searchTools(query");
		expect(text).toContain("The `codemode` section of the system prompt lists the tools scripts can call");
		expect(text).not.toContain("`models`");
		expect(codemodeDescription(true)).toContain("`models`");
	});

	it("lists callable tools as declarations, grouped by namespace, with namespace descriptions", () => {
		const section = codemodeSection(
			[tool("read", "Read a file."), tool("mcp__github__list_issues", "List issues.")],
			[GITHUB],
			3000,
		)!;
		expect(section).toContain("### `read`\nRead a file.");
		expect(section).toContain("read(args: {");
		expect(section).toContain("## github\nGitHub MCP server");
		// Tools before namespaces; a namespace's tools after its heading.
		expect(section.indexOf("### `read`")).toBeLessThan(section.indexOf("## github"));
		expect(section.indexOf("## github")).toBeLessThan(section.indexOf("### `mcp__github__list_issues`"));
		expect(section).toContain("Promise<string>");
	});

	it("lists what fits the budget, every namespace before any is complete, and says what is left out", () => {
		const github = Array.from({ length: 30 }, (_, index) => tool(`mcp__github__tool${index}`, "x".repeat(200)));
		const section = codemodeSection([tool("read", "Read a file."), ...github], [GITHUB], 400)!;
		expect(section).toContain("### `read`");
		expect(section).toContain("## github (some tools not listed)");
		expect(section).not.toContain("tool29");
		expect(codemodeSection([...github], [GITHUB], 10)!).toContain("## github (tools not listed)");
		expect(codemodeSection([], [GITHUB], 3000)).toBeUndefined();
	});

	it("uses the longest matching namespace prefix", () => {
		const section = codemodeSection(
			[tool("mcp__github__x", "x")],
			[{ name: "git", prefix: "mcp__git" }, GITHUB],
			3000,
		)!;
		expect(section).toContain("## github");
		expect(section).not.toContain("## git\n");
	});

	it("renders the section from the conversation's callable tools into the system prompt", async () => {
		const setup = chatSetup();
		setup.registry.install(createCodemodeExtension({ sandbox: new CodemodeSandbox(), namespaces: [GITHUB] }));
		setup.registry.install({
			name: "tools",
			tools: [
				tool("read", "Read a file."),
				tool("mcp__github__list_issues", "List issues.", { callers: ["tools"] }),
				tool("mcp__github__get_issue", "Get an issue.", { deferred: true }),
			],
		});
		setup.faux.setResponses([fauxAssistantMessage([fauxText("hi")]) as AssistantMessage]);
		const { harness, root } = await openChat(new MemoryStorage(), setup);
		await (await root.submit({ type: "input", content: "go" }, context)).wait(context);
		const system = (await allEntries(root)).find((entry) => entry.kind === "pi.system")!;
		const sections = (system.model![0] as { sections?: Record<string, string> }).sections!;
		expect(sections.codemode).toContain("### `read`");
		expect(sections.codemode).toContain("### `mcp__github__list_issues`");
		// Deferred tools are found with searchTools(), not listed.
		expect(sections.codemode).not.toContain("mcp__github__get_issue");
		// The code mode tool itself is not callable from scripts.
		expect(sections.codemode).not.toContain("### `codemode`");
		// The tool declaration carries the script grammar; pi-ai applies it only for models that support it.
		const tools = (system.model![0] as { toolsAdded?: { name: string; constrainedSampling?: unknown }[] })
			.toolsAdded!;
		expect(tools.find((candidate) => candidate.name === "codemode")?.constrainedSampling).toEqual({
			type: "grammar",
			variants: { openai_lark: CODEMODE_SOURCE_GRAMMAR },
		});
		await harness.close(context);
	});
});