import type { PrismaClient } from "@rakazo/db";
import { describe, expect, it, vi } from "vitest";
import { formatCurrentTimeInstruction, formatLocalDate, loadUserTimeZone } from "./current-time.js";

describe("formatCurrentTimeInstruction", () => {
  it("anchors the present moment in UTC with the weekday and no sub-second noise", () => {
    const line = formatCurrentTimeInstruction(null, new Date("2026-09-17T14:55:41.123Z"));
    expect(line).toContain("Current date and time: Thursday, 2026-09-17T14:55:41Z (UTC).");
    expect(line).not.toContain(".123");
    expect(line).toContain("convert it to the user's time zone when one is known");
  });

  it("states the user's local time with the zone and offset", () => {
    const line = formatCurrentTimeInstruction(
      "Europe/Berlin",
      new Date("2026-09-17T14:55:41.123Z"),
    );
    expect(line).toContain(
      "Current date and time: Thursday, 2026-09-17T16:55:41+02:00 (Europe/Berlin, the user's time zone).",
    );
    expect(line).not.toContain("convert it to the user's time zone");
  });

  it("uses the local date when the zone is still on the previous day", () => {
    const line = formatCurrentTimeInstruction(
      "America/Los_Angeles",
      new Date("2026-01-01T03:00:00Z"),
    );
    expect(line).toContain("Wednesday, 2025-12-31T19:00:00-08:00 (America/Los_Angeles");
  });

  it("prints fractional-hour offsets", () => {
    const now = new Date("2026-09-17T14:55:41Z");
    expect(formatCurrentTimeInstruction("Asia/Kolkata", now)).toContain(
      "2026-09-17T20:25:41+05:30 (Asia/Kolkata",
    );
    expect(formatCurrentTimeInstruction("Asia/Kathmandu", now)).toContain(
      "2026-09-17T20:40:41+05:45 (Asia/Kathmandu",
    );
  });

  it("marks a user who lives in UTC with Z", () => {
    expect(formatCurrentTimeInstruction("UTC", new Date("2026-09-17T14:55:41Z"))).toContain(
      "Thursday, 2026-09-17T14:55:41Z (UTC, the user's time zone).",
    );
  });

  it("falls back to UTC for an unknown zone", () => {
    expect(
      formatCurrentTimeInstruction("Mars/Olympus", new Date("2026-09-17T14:55:41Z")),
    ).toContain("Current date and time: Thursday, 2026-09-17T14:55:41Z (UTC).");
  });

  it("tells the model not to guess the date from training data or quoted timestamps", () => {
    const line = formatCurrentTimeInstruction(null, new Date("2026-01-01T00:00:00Z"));
    expect(line).toContain("Never infer today's date from your training data");
    expect(line).toContain("write absolute dates");
  });

  it("defaults to the real clock", () => {
    const before = Date.now();
    const line = formatCurrentTimeInstruction(undefined);
    const match = /(\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2})Z/.exec(line);
    expect(match).not.toBeNull();
    const stamped = Date.parse(`${match![1]}Z`);
    expect(Math.abs(stamped - before)).toBeLessThan(5_000);
  });
});

describe("loadUserTimeZone", () => {
  const prismaWith = (timeZone: string | null | undefined) => {
    const findUnique = vi.fn(async () => (timeZone === undefined ? null : { timeZone }));
    return {
      prisma: { userProfile: { findUnique } } as unknown as PrismaClient,
      findUnique,
    };
  };

  it("reads the zone from the user's profile", async () => {
    const { prisma, findUnique } = prismaWith("Europe/Berlin");
    await expect(loadUserTimeZone(prisma, "user-1")).resolves.toBe("Europe/Berlin");
    expect(findUnique).toHaveBeenCalledWith({
      where: { userId: "user-1" },
      select: { timeZone: true },
    });
  });

  it("returns nothing without a profile, a zone, or a zone the runtime knows", async () => {
    await expect(loadUserTimeZone(prismaWith(undefined).prisma, "user-1")).resolves.toBeUndefined();
    await expect(loadUserTimeZone(prismaWith(null).prisma, "user-1")).resolves.toBeUndefined();
    await expect(
      loadUserTimeZone(prismaWith("Mars/Olympus").prisma, "user-1"),
    ).resolves.toBeUndefined();
  });
});

describe("formatLocalDate", () => {
  it("is the user's local date, or the UTC date without a known zone", () => {
    const now = new Date("2026-01-01T03:00:00Z");
    expect(formatLocalDate("America/Los_Angeles", now)).toBe("2025-12-31");
    expect(formatLocalDate("Not/AZone", now)).toBe("2026-01-01");
    expect(formatLocalDate(null, now)).toBe("2026-01-01");
  });
});