import { describe, expect, it } from "vitest";
import { existsSync, readFileSync } from "node:fs";
import { CrystalAssets } from "../src/game/rom/assets";
import { romRevision } from "../src/game/rom/revision";
import { CRYSTAL_ROMS, validateRom } from "../src/rom/validate";
import { emptyBattleTowerState, loadOpponent } from "../src/game/scripts/battle-tower";
import type { SpecialContext } from "../src/game/scripts/special-context";

/** The user's 1.1 cartridge and PRET's rebuilds of the other English ones
 * (`make crystal crystal_au` in .reference/pokecrystal), each skipped when
 * absent. */
const cartridges = [
  { revision: "1.1", path: process.env.CRYSTAL_ROM_PATH ?? "Pokemon - Crystal Version (UE) (V1.1) [C][!].gbc", rom: CRYSTAL_ROMS[0] },
  { revision: "1.0", path: ".reference/pokecrystal/pokecrystal.gbc", rom: CRYSTAL_ROMS[1] },
  { revision: "au", path: ".reference/pokecrystal/pokecrystal_au.gbc", rom: CRYSTAL_ROMS[2] },
] as const;

for (const { revision, path, rom } of cartridges)
  describe.skipIf(!existsSync(path))(`the ${revision} cartridge`, () => {
    const bytes = existsSync(path) ? new Uint8Array(readFileSync(path)) : new Uint8Array();
    it("is accepted under its name and recognised from its header", async () => {
      // CRYSTAL_ROM_PATH may point the 1.1 entry at another cartridge.
      const assets = new CrystalAssets(bytes);
      const own = cartridges.find((c) => c.revision === romRevision(assets.reader))!;
      expect(await validateRom(new File([bytes], "crystal.gbc"))).toMatchObject({ sha1: own.rom.sha1, name: own.rom.name });
      if (revision !== "1.1" || !process.env.CRYSTAL_ROM_PATH) expect(own.revision).toBe(revision);
      // One changed byte is a modified ROM.
      const changed = bytes.slice();
      changed[0x7fff] ^= 1;
      await expect(validateRom(new File([changed], "crystal.gbc"))).rejects.toThrow("not a supported English");
    });

    it("draws Battle Tower trainers from all 70, or from the first 21 on 1.0", () => {
      const assets = new CrystalAssets(bytes);
      let seed = 84;
      const context = {
        reader: assets.reader,
        data: assets.pokemon,
        random: () => {
          seed = (seed * 1103515245 + 12345) >>> 0;
          return (seed >>> 16) & 255;
        },
        text: () => ({ player: "KAWA", rival: "SILVER", mom: "MOM", strings: {}, weekday: "SUNDAY" }),
      } as unknown as SpecialContext;
      const drawn = new Set<number>();
      for (let draw = 0; draw < 2000; draw++) {
        const bt = { ...emptyBattleTowerState(), levelGroup: 1 + (draw % 10) };
        drawn.add(loadOpponent(context, bt).trainer);
      }
      const limit = romRevision(assets.reader) === "1.0" ? 21 : 70;
      expect(Math.max(...drawn)).toBe(limit - 1);
      expect(drawn.size).toBe(limit);
    });
  });