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 own InitDisplayForRedCredits and Credits run with their
 * interrupts after the game has booted; each video frame the screen's
 * background map, the banner's 16 tiles, wBGPals2's three palettes,
 * wLYOverrides and the parser's position and timer are compared with
 * CreditsMachine's, from the first parse to well past THE END. Without B
 * and with B held (which only shortens credits seen before). */
for (const skip of [false, true])
  test(`Credits match the cartridge frame by frame${skip ? " with B held" : ""}`, async ({ page }) => {
    test.setTimeout(300_000);
    const { at, routine } = loadSymbols();
    const a = {
      romBank: at("hROMBank"),
      pos: at("wCreditsPos"),
      timer: at("wCreditsTimer"),
      bgPals2: at("wBGPals2"),
      lyOverrides: at("wLYOverrides"),
      program: at("wOverworldMapBlocks"),
      stackTop: at("wStackTop"),
    };
    const init = routine("InitDisplayForRedCredits"),
      credits = routine("Credits");
    await openReference(page);
    const result = await page.evaluate(
      async ({ a, init, credits, skip }) => {
        const { BinjgbEmulator } = await import("/src/emulator/binjgb.ts");
        const { CrystalAssets } = await import("/src/game/rom/assets.ts");
        const { CreditsMachine } = await import("/src/game/scripts/league.ts");
        const { hallOfFameTiles } = await import("/src/game/scripts/hall-of-fame.ts");
        const rom = new Uint8Array(
          await (document.querySelector("#reference-fixture") as HTMLInputElement).files![0].arrayBuffer(),
        );
        const assets = new CrystalAssets(rom);
        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);
        // Boot to the intro so the interrupt handlers and hardware are set up.
        reference.advanceFrames(600);
        // DI; SP=wStackTop; EI; InitDisplayForRedCredits; B = the status
        // flags (bit 6: the Hall of Fame); Credits; a sentinel.
        const bank = (n: number) => [0x3e, n, 0xe0, a.romBank & 255, 0xea, 0, 0x20];
        const sentinel = a.program + 0x80;
        const program = [
          0xf3,
          0x31, a.stackTop & 255, a.stackTop >> 8,
          0xfb,
          ...bank(init.bank),
          0xcd, init.address & 255, init.address >> 8,
          ...bank(credits.bank),
          0x06, skip ? 0x40 : 0,
          0xcd, credits.address & 255, credits.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);
        if (skip) reference.setButton("b", true);
        const machine = new CreditsMachine(assets.reader, hallOfFameTiles(assets.pokemon, 0), skip);
        type State = { map: number[]; tiles: number[]; pals: number[]; ly: number[]; pos: number; timer: number; lcd?: number[] };
        // The parser's work RAM at line 143 (the frame's logic has run,
        // its VBlank has not), then what that VBlank presents at line 152:
        // the BG map, the banner's tiles and the palettes in CRAM.
        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 sample = (): State => {
          toLine(143);
          const wram = {
            ly: [read(a.lyOverrides + 0x1f), read(a.lyOverrides + 0x87)],
            pos: read(a.pos) | (read(a.pos + 1) << 8),
            timer: read(a.timer),
          };
          toLine(152);
          const cram = Array.from({ length: 12 }, (_, i) => {
            write(0xff68, i * 2);
            const low = read(0xff69);
            write(0xff68, i * 2 + 1);
            return low | (read(0xff69) << 8);
          });
          const state = {
            map: Array.from({ length: 360 }, (_, i) => read(0x9800 + Math.floor(i / 20) * 32 + (i % 20))),
            tiles: Array.from({ length: 256 }, (_, i) => read(0x9000 + i)),
            pals: cram,
            ...wram,
            lcd: [read(0xff44), read(0xff41) & 3],
          };
          reference.advanceCycles(456 * 140);
          return state;
        };
        const native = (): State => {
          const d = machine.debug();
          return {
            map: [...machine.shown],
            tiles: Array.from(machine.vram.subarray(0, 256)),
            pals: machine.paletteWords(),
            ly: [d.lyOverride, d.lyOverride],
            pos: d.pos,
            timer: d.timer,
          };
        };
        // Sample once a frame at the last visible line: the frame's logic
        // has run and its VBlank has not.
        let guard = 0;
        while (read(a.pos) === 0 && read(a.pos + 1) === 0 && guard++ < 300) reference.advanceFrames(1);
        while (read(0xff44) !== 143 && guard++ < 100000) reference.advanceCycles(16);
        const original: State[] = [];
        for (let frame = 0; frame < 12000 && read(sentinel) !== 0x42; frame++) original.push(sample());
        const nativeFrames: State[] = [];
        const present = () => {
          const before = native();
          machine.vblank();
          const after = native();
          nativeFrames.push({ ...after, ly: before.ly, pos: before.pos, timer: before.timer });
        };
        for (let frame = 0; frame < original.length + 8; frame++) {
          const logic = machine.step(skip ? "b" : "");
          let next = logic.next();
          while (!next.done) {
            present();
            next = logic.next();
          }
          present();
        }
        // Positions between two waits are a parse in progress, whose own
        // progress the native parser does not model: compare the parser
        // where it rests, and the screen always.
        const { KANTO } = await import("/src/game/rom/profile.ts");
        const boundaries = new Set<number>([0]);
        for (let p = 0, guard = 0; guard < 1024; guard++) {
          const command = rom[KANTO.CreditsScript + p++];
          if (command === 0xff) {
            boundaries.add(p);
            break;
          }
          if (command === 0xfe || command === 0xfa) boundaries.add(++p);
          else if (command === 0xfd || command < 0xf9) p++;
        }
        const rest = ({ lcd: _, ...x }: State) => (boundaries.has(x.pos) ? x : { ...x, pos: -1, timer: -1 });
        const same = (x: State, y: State) => JSON.stringify(rest(x)) === JSON.stringify(boundaries.has(x.pos) ? y : rest(y));
        // The first emulator sample falls after the first parse; find its
        // native frame, then every later frame must match in order.
        const offset = nativeFrames.findIndex((frame) => frame.pos === original[0].pos && same(original[0], frame));
        const mismatches: unknown[] = [];
        if (offset >= 0)
          original.forEach((frame, i) => {
            const mine = nativeFrames[offset + i];
            if (mismatches.length >= 5 || (mine && same(frame, mine))) return;
            if (!mine) return void mismatches.push({ frame: i, native: "missing" });
            const diff: Record<string, unknown> = { frame: i, pos: frame.pos, timer: [frame.timer, mine.timer], lcd: frame.lcd };
            for (const key of ["map", "tiles", "pals", "ly"] as const) {
              const cells = frame[key].flatMap((value, index) =>
                value === mine[key][index] ? [] : [`${index}:${value}/${mine[key][index]}`],
              );
              if (cells.length) diff[key] = cells.slice(0, 12).join(" ");
            }
            if (frame.pos !== mine.pos) diff.nativePos = mine.pos;
            mismatches.push(diff);
          });
        return {
          frames: original.length,
          offset,
          first: original[0] && { pos: original[0].pos, timer: original[0].timer },
          debugFirst: offset < 0 ? [original[0], ...nativeFrames.slice(0, 4)].map((x) => ({ ...x, map: x.map.slice(80, 140).join(","), tiles: x.tiles.slice(0, 16).join(",") })) : undefined,
          endPos: original.at(-1)?.pos,
          mismatches,
        };
      },
      { a, init, credits, skip },
    );
    expect(result.offset, JSON.stringify(result.debugFirst)).toBeGreaterThanOrEqual(0);
    expect(result.frames).toBeGreaterThan(skip ? 3000 : 8000);
    expect(result.mismatches).toEqual([]);
  });