import { readFileSync } from "node:fs";
import { join } from "node:path";
import { describe, expect, it } from "vitest";
import { Session } from "../../src/harness/session/session.js";
import { JsonlSessionStorage } from "../../src/harness/session/storage/jsonl.js";
import { InMemorySessionStorage } from "../../src/harness/session/storage/memory.js";
import type { SessionStorage } from "../../src/harness/types.js";
import { createAssistantMessage, createTempDir, createUserMessage, getLatestTempDir } from "./session-test-utils.js";

async function runSessionSuite(
	name: string,
	createStorage: () => SessionStorage | Promise<SessionStorage>,
	inspect?: () => void,
) {
	describe(name, () => {
		it("appends messages and builds context in order", async () => {
			const session = new Session(await createStorage());
			await session.appendMessage(createUserMessage("one"));
			await session.appendMessage(createAssistantMessage("two"));
			const context = await session.buildContext();
			expect(context.messages.map((message) => message.role)).toEqual(["user", "assistant"]);
		});

		it("tracks model and thinking level changes", async () => {
			const session = new Session(await createStorage());
			await session.appendMessage(createUserMessage("one"));
			await session.appendModelChange("openai", "gpt-4.1");
			await session.appendThinkingLevelChange("high");
			const context = await session.buildContext();
			expect(context.thinkingLevel).toBe("high");
			expect(context.model).toEqual({ provider: "openai", modelId: "gpt-4.1" });
		});

		it("supports branching by moving the leaf and appending a new branch", async () => {
			const session = new Session(await createStorage());
			const user1 = await session.appendMessage(createUserMessage("one"));
			const assistant1 = await session.appendMessage(createAssistantMessage("two"));
			await session.appendMessage(createUserMessage("three"));
			await session.moveTo(user1);
			await session.appendMessage(createAssistantMessage("branched"));
			const branch = await session.getBranch();
			expect(branch.map((entry) => entry.id)).toContain(user1);
			expect(branch.map((entry) => entry.id)).not.toContain(assistant1);
			const context = await session.buildContext();
			expect(context.messages.map((message) => message.role)).toEqual(["user", "assistant"]);
		});

		it("supports moving the leaf to root", async () => {
			const session = new Session(await createStorage());
			await session.appendMessage(createUserMessage("one"));
			await session.moveTo(null);
			expect(await session.getLeafId()).toBeNull();
			expect((await session.buildContext()).messages).toEqual([]);
		});

		it("reconstructs compaction summaries in context", async () => {
			const session = new Session(await createStorage());
			await session.appendMessage(createUserMessage("one"));
			await session.appendMessage(createAssistantMessage("two"));
			const user2 = await session.appendMessage(createUserMessage("three"));
			await session.appendMessage(createAssistantMessage("four"));
			await session.appendCompaction("summary", user2, 1234);
			await session.appendMessage(createUserMessage("five"));
			const context = await session.buildContext();
			expect(context.messages[0]?.role).toBe("compactionSummary");
			expect(context.messages).toHaveLength(4);
		});

		it("supports moving with branch summary entries in context", async () => {
			const session = new Session(await createStorage());
			const user1 = await session.appendMessage(createUserMessage("one"));
			const summaryId = await session.moveTo(user1, { summary: "summary text" });
			expect(summaryId).toBeTruthy();
			const summaryEntry = await session.getEntry(summaryId!);
			expect(summaryEntry).toMatchObject({ type: "branch_summary", parentId: user1, fromId: user1 });
			const context = await session.buildContext();
			expect(context.messages[1]?.role).toBe("branchSummary");
		});

		it("supports custom message entries in context", async () => {
			const session = new Session(await createStorage());
			await session.appendMessage(createUserMessage("one"));
			await session.appendCustomMessageEntry("custom", "hello", true, { ok: true });
			const context = await session.buildContext();
			expect(context.messages[1]?.role).toBe("custom");
		});

		it("supports labels and session info entries without affecting context", async () => {
			const session = new Session(await createStorage());
			const user1 = await session.appendMessage(createUserMessage("one"));
			await session.appendLabel(user1, "checkpoint");
			await session.appendSessionName("name");
			const entries = await session.getEntries();
			expect(entries.some((entry) => entry.type === "label")).toBe(true);
			expect(entries.some((entry) => entry.type === "session_info")).toBe(true);
			expect(await session.getLabel(user1)).toBe("checkpoint");
			expect(await session.getSessionName()).toBe("name");
			expect((await session.buildContext()).messages).toHaveLength(1);
		});

		it("rejects labels for missing entries", async () => {
			const session = new Session(await createStorage());
			await expect(session.appendLabel("missing", "checkpoint")).rejects.toThrow("Entry missing not found");
		});

		it("persists leaf changes and appended entries via storage", async () => {
			const storage = await createStorage();
			const session = new Session(storage);
			const user1 = await session.appendMessage(createUserMessage("one"));
			await session.appendMessage(createAssistantMessage("two"));
			await session.appendLabel(user1, "checkpoint");
			await session.appendSessionName("name");
			await session.moveTo(user1);
			await session.appendMessage(createAssistantMessage("branched"));
			const session2 = new Session(storage);
			const context = await session2.buildContext();
			expect(context.messages.map((message) => message.role)).toEqual(["user", "assistant"]);
			expect(await session2.getLabel(user1)).toBe("checkpoint");
			expect(await session2.getSessionName()).toBe("name");
			inspect?.();
		});
	});
}

runSessionSuite("Session with in-memory storage", () => new InMemorySessionStorage());

runSessionSuite(
	"Session with JSONL storage",
	async () => {
		const dir = createTempDir();
		return await JsonlSessionStorage.create(join(dir, "session.jsonl"), { cwd: dir, sessionId: "session-1" });
	},
	() => {
		const dir = getLatestTempDir();
		const filePath = join(dir, "session.jsonl");
		const lines = readFileSync(filePath, "utf8").trim().split("\n");
		expect(lines.length).toBeGreaterThan(1);
		const header = JSON.parse(lines[0]!);
		expect(header.type).toBe("session");
		expect(header.version).toBe(3);
		for (const line of lines.slice(1)) {
			const entry = JSON.parse(line);
			expect(entry.type).not.toBe("entry");
			expect(entry.type).not.toBe("leaf");
			expect(typeof entry.id).toBe("string");
		}
	},
);
