import { test, expect } from "@playwright/test";
import { existsSync } from "node:fs";
import { romPath, symbolsPath, loadSymbols, openReference } from "./reference-fixture";

test.skip(!existsSync(romPath) || !existsSync(symbolsPath), "Needs private ROM and reference symbols.");

/** The cartridge's MagnetTrain runs with its interrupts after a boot, in
 * Saffron's station at day; each frame (sampled in VBlank, after the
 * cutscene's handler) its OAM, hSCX and wLYOverrides' bands, the BG map
 * and attributes, the icon's tiles and the palettes in CRAM are compared
 * with MagnetTrainMachine's, both ways and for both players. */
for (const toGoldenrod of [false, true])
  for (const female of [false, true])
    test(`MagnetTrain matches the cartridge frame by frame ${toGoldenrod ? "to Goldenrod" : "to Saffron"}${female ? " as Kris" : ""}`, async ({ page }) => {
      test.setTimeout(240_000);
      const { at, routine } = loadSymbols();
      const a = {
        romBank: at("hROMBank"),
        program: at("wOverworldMapBlocks"),
        stackTop: at("wStackTop"),
        scriptVar: at("wScriptVar"),
        gender: at("wPlayerGender"),
        timeOfDay: at("wTimeOfDay"),
        mapGroup: at("wMapGroup"),
        mapNumber: at("wMapNumber"),
        tileset: at("wMapTileset"),
        jumptable: at("wJumptableIndex"),
        position: at("wMagnetTrainPosition"),
        lyOverrides: at("wLYOverrides"),
        scx: at("hSCX"),
      };
      const train = routine("MagnetTrain");
      const TEARDOWN = 8;
      await openReference(page);
      const result = await page.evaluate(
        async ({ a, train, toGoldenrod, female }) => {
          const { BinjgbEmulator } = await import("/src/emulator/binjgb.ts");
          const { CrystalAssets } = await import("/src/game/rom/assets.ts");
          const { MagnetTrainMachine } = await import("/src/game/scripts/magnet-train.ts");
          const { rgb } = await import("/src/game/scripts/screen.ts");
          const rom = new Uint8Array(
            await (document.querySelector("#reference-fixture") as HTMLInputElement).files![0].arrayBuffer(),
          );
          const assets = new CrystalAssets(rom);
          const station = assets.map("25:9");
          const reference = new BinjgbEmulator();
          await reference.load(rom, document.createElement("canvas"));
          reference.setMuted(true);
          const read = (p: number) => reference.readMemory(p);
          const write = (p: number, v: number) => reference.writeMemory(p, v & 255);
          reference.advanceFrames(600);
          write(0xff70, 1);
          write(a.gender, female ? 1 : 0);
          write(a.timeOfDay, 1);
          write(a.mapGroup, 25);
          write(a.mapNumber, 9);
          write(a.tileset, station.tileset);
          write(a.scriptVar, toGoldenrod ? 1 : 0);
          write(a.jumptable, 0xff);
          const sentinel = a.program + 0x80;
          const program = [
            0xf3, 0x31, a.stackTop & 255, a.stackTop >> 8, 0xfb,
            0x3e, train.bank, 0xe0, a.romBank & 255, 0xea, 0, 0x20,
            0xcd, train.address & 255, train.address >> 8,
            0x3e, 0x42, 0xea, sentinel & 255, sentinel >> 8,
            0x18, 0xfe,
          ];
          write(sentinel, 0);
          program.forEach((v, i) => write(a.program + i, v));
          reference.setProgramCounter(a.program);
          const toLine = (line: number) => {
            for (let guard = 0; read(0xff44) !== line; guard++) {
              if (guard > 20000) throw new Error("The LCD does not reach the line.");
              reference.advanceCycles(16);
            }
          };
          const cram = (index: number, obj: boolean) => {
            write(obj ? 0xff6a : 0xff68, index);
            return read(obj ? 0xff6b : 0xff69);
          };
          type State = { oam: number[]; bands: number[]; map: number[]; attrs: number[]; tiles: number[]; bg: number[]; obj: number[] };
          const sample = (): State => {
            toLine(152);
            write(0xff4f, 0);
            const map = Array.from({ length: 18 * 32 }, (_, i) => read(0x9800 + i));
            write(0xff4f, 1);
            const attrs = Array.from({ length: 18 * 32 }, (_, i) => read(0x9800 + i) & 7);
            write(0xff4f, 0);
            const state = {
              oam: Array.from({ length: 16 }, (_, i) => read(0xfe00 + i)),
              // Lines 1-143 take wLYOverrides (pushed at VBlank); line 0
              // takes hSCX, which already holds the next frame's here.
              bands: [read(a.lyOverrides), read(a.lyOverrides + 47), read(a.lyOverrides + 95)],
              map,
              attrs,
              tiles: Array.from({ length: 128 }, (_, i) => read(0x8000 + i)),
              bg: Array.from({ length: 64 }, (_, i) => cram(i, false)),
              obj: Array.from({ length: 16 }, (_, i) => cram(i, true)),
            };
            reference.advanceCycles(456 * 140);
            return state;
          };
          // Wait for the first run through: its jumptable entry leaves 1.
          let guard = 0;
          while (read(a.jumptable) !== 1 && guard++ < 300) reference.advanceFrames(1);
          const original: State[] = [];
          for (let frame = 0; frame < 600 && read(sentinel) !== 0x42; frame++) original.push(sample());
          const time = 1;
          const host = {
            reader: assets.reader,
            female,
            tiles: () => assets.tileset(station).graphics,
            palettes: () => ({
              bg: assets.palettes({ ...station, environment: 1 }, time),
              obj: Array.from({ length: 8 }, (_, i) => assets.objectPalette(i, time)),
            }),
          };
          const machine = new MagnetTrainMachine(host, toGoldenrod);
          const tiles = machine.tiles();
          const word = (c: number[]) => Math.round((c[0] * 31) / 255) | (Math.round((c[1] * 31) / 255) << 5) | (Math.round((c[2] * 31) / 255) << 10);
          const native: State[] = [];
          const present = () => {
            const screen = machine.screen(tiles, "");
            const oam = screen.sprites.flatMap((s) => [
              (s.y + 16) & 255,
              (s.x + 8) & 255,
              s.tile - 0x100,
              (s.behind ? 0x80 : 0) | (s.flipY ? 0x40 : 0) | (s.flipX ? 0x20 : 0) | s.palette,
            ]);
            const d = machine.debug();
            const pal = (list: number[][][]) => list.flatMap((p) => p.flatMap((c) => { const w = word(c); return [w & 255, w >> 8]; }));
            native.push({
              oam: [...oam, ...Array(16 - oam.length).fill(-1)].slice(0, 16),
              bands: [d.bands.bushes, d.bands.train, d.bands.bushes],
              map: machine.bg.flat(),
              attrs: machine.attrs.flat(),
              tiles: Array.from(tiles.subarray(0x100 * 16, 0x108 * 16)),
              bg: pal(screen.palettes as number[][][]),
              obj: pal(screen.objPalettes.slice(0, 2) as number[][][]),
            });
          };
          machine.step();
          present();
          machine.setPalettes();
          present();
          while (!machine.done) {
            machine.step();
            present();
          }
          // The emulator's OAM keeps cleared sprites' bytes; compare the
          // four the icon uses, or nothing before it appears.
          const same = (o: State, n: State) => {
            const oam = n.oam[0] === -1 ? true : JSON.stringify(o.oam) === JSON.stringify(n.oam);
            return (
              oam &&
              JSON.stringify([o.bands, o.map, o.attrs, o.tiles, o.bg, o.obj]) ===
                JSON.stringify([n.bands, n.map, n.attrs, n.tiles, n.bg, n.obj])
            );
          };
          // The first sample can fall a frame either side of the first run
          // through: align on the offset where the frames agree.
          const offset = [0, 1, -1].find((off) => native.slice(2, 40).every((n, i) => original[i + 2 + off] && same(original[i + 2 + off], n))) ?? 0;
          const mismatches: unknown[] = [];
          // The first sample falls in the VBlank of the first run through,
          // before its overrides are pushed: compare from the next frame.
          native.forEach((n, i) => {
            if (i === 0) return;
            const o = original[i + offset];
            if (mismatches.length >= 4) return;
            if (!o) return void mismatches.push({ frame: i, original: "missing" });
            if (same(o, n)) return;
            const diff: Record<string, unknown> = { frame: i };
            for (const key of ["oam", "bands", "map", "attrs", "tiles", "bg", "obj"] as const) {
              const cells = o[key].flatMap((value, index) => (value === n[key][index] ? [] : [`${index}:${value}/${n[key][index]}`]));
              if (cells.length) diff[key] = cells.slice(0, 10).join(" ");
            }
            mismatches.push(diff);
          });
          return { original: original.length - offset, native: native.length, offset, mismatches };
        },
        { a, train, toGoldenrod, female },
      );
      expect(result.mismatches, JSON.stringify(result)).toEqual([]);
      // The cartridge's teardown frames follow the arrival.
      expect(result.original).toBe(result.native + TEARDOWN);
    });