import { describe, expect, it, vi } from "@suaveplan/testing/runner";
import { SqliteError } from "../errors/index.js";
import { createWasmDriver } from "./wasm-driver.js";

// Injectable worker factory avoids spawning real Workers in Node/Vitest environment
function makeWorkerFactory(
    handler: (
        msg: unknown,
        post: (data: unknown) => void
    ) => void | Promise<void>
): () => Worker {
    return () => {
        let onmessage: ((ev: MessageEvent) => void) | null = null;
        let onerror: ((ev: ErrorEvent) => void) | null = null;

        const post = (data: unknown) => {
            if (onmessage) {
                onmessage({ data } as MessageEvent);
            }
        };

        const worker = {
            get onmessage() {
                return onmessage;
            },
            set onmessage(fn: ((ev: MessageEvent) => void) | null) {
                onmessage = fn;
            },
            get onerror() {
                return onerror;
            },
            set onerror(fn: ((ev: ErrorEvent) => void) | null) {
                onerror = fn;
            },
            postMessage: (msg: unknown) => {
                void Promise.resolve().then(() => handler(msg, post));
            },
            terminate: vi.fn(),
        };

        return worker as unknown as Worker;
    };
}

function makeSuccessWorker(): () => Worker {
    return makeWorkerFactory((msg, post) => {
        const m = msg as {
            type: string;
            id: number;
            sql?: string;
            params?: unknown[];
        };
        if (m.type === "init") {
            post({ id: m.id, ok: true, result: { type: "ready" } });
        } else if (m.type === "query") {
            post({ id: m.id, ok: true, result: [["value1"], ["value2"]] });
        } else if (m.type === "execute") {
            post({ id: m.id, ok: true, result: { rowsAffected: 1 } });
        } else if (m.type === "close") {
            post({ id: m.id, ok: true, result: { type: "closed" } });
        }
    });
}

describe("createWasmDriver", () => {
    it("creates driver and resolves on successful init", {
        timeout: 30000,
    }, async () => {
        const { db, close } = await createWasmDriver(
            undefined,
            makeSuccessWorker()
        );
        expect(db).toBeDefined();
        await close();
    });

    it("query returns rows from worker", { timeout: 30000 }, async () => {
        const { db, close } = await createWasmDriver(
            undefined,
            makeSuccessWorker()
        );
        const rows = await db.query("SELECT * FROM t");
        expect(rows).toEqual([["value1"], ["value2"]]);
        await close();
    });

    it("execute returns rowsAffected from worker", {
        timeout: 30000,
    }, async () => {
        const { db, close } = await createWasmDriver(
            undefined,
            makeSuccessWorker()
        );
        const result = await db.execute("INSERT INTO t VALUES (?)", [1]);
        expect(result.rowsAffected).toBe(1);
        await close();
    });

    it("close() is idempotent", { timeout: 30000 }, async () => {
        const { close } = await createWasmDriver(
            undefined,
            makeSuccessWorker()
        );
        await close();
        await expect(close()).resolves.toBeUndefined();
    });

    it("rejects pending requests when close() is called", {
        timeout: 30000,
    }, async () => {
        let postFn: ((data: unknown) => void) | null = null;

        const slowWorker = makeWorkerFactory((msg, post) => {
            const m = msg as { type: string; id: number };
            if (m.type === "init") {
                post({ id: m.id, ok: true, result: { type: "ready" } });
            } else if (m.type === "close") {
                post({ id: m.id, ok: true, result: { type: "closed" } });
            }
            // query messages hang — capture postFn for manual resolution
            if (m.type === "query") {
                postFn = post;
            }
        });

        const { db, close } = await createWasmDriver(undefined, slowWorker);

        // Fire a query that will hang — capture the promise
        const queryPromise = db.query("SELECT 1");
        // Ensure the query is actually sent before closing
        await Promise.resolve();

        // close() should drain pending
        await close();

        // The hanging query should now reject
        await expect(queryPromise).rejects.toBeInstanceOf(SqliteError);

        // Suppress unused variable warning
        void postFn;
    });

    it("throws SqliteError on worker init failure", {
        timeout: 30000,
    }, async () => {
        const failWorker = makeWorkerFactory((msg, post) => {
            const m = msg as { type: string; id: number };
            if (m.type === "init") {
                post({
                    id: m.id,
                    ok: false,
                    error: "sqlite-wasm init failed: load error",
                });
            } else if (m.type === "close") {
                post({ id: m.id, ok: true, result: { type: "closed" } });
            }
        });

        await expect(
            createWasmDriver(undefined, failWorker)
        ).rejects.toBeInstanceOf(SqliteError);
        await expect(
            createWasmDriver(undefined, failWorker)
        ).rejects.toMatchObject({ code: "SQLITE.DRIVER_INIT_FAILED" });
    });

    it("worker error event rejects pending requests", {
        timeout: 30000,
    }, async () => {
        let fireError: ((ev: ErrorEvent) => void) | null = null;

        const hangingWorker = makeWorkerFactory((msg, post) => {
            const m = msg as { type: string; id: number };
            if (m.type === "init") {
                post({ id: m.id, ok: true, result: { type: "ready" } });
            }
            // query messages hang — worker "crashes" below
        });

        const patchedFactory = () => {
            const worker = hangingWorker();
            Object.defineProperty(worker, "onerror", {
                set: (fn: (ev: ErrorEvent) => void) => {
                    fireError = fn;
                },
                get: () => fireError,
                configurable: true,
            });
            return worker;
        };

        const { db } = await createWasmDriver(undefined, patchedFactory);

        const queryPromise = db.query("SELECT 1");
        await Promise.resolve();

        // Simulate worker crash — onerror should reject all pending promises
        fireError?.({ message: "Worker crashed" } as ErrorEvent);

        await expect(queryPromise).rejects.toBeInstanceOf(SqliteError);
    });
});