// Autonomous boot probe. Started from emulator.tsx when WIN95_PROBE=1.
// Writes status + screenshot to /tmp so an outer loop can read them
// without DevTools or CDP.

import * as fs from "fs";

const STATUS_FILE = "/tmp/win95-probe.json";
const SCREEN_FILE = "/tmp/win95-screen.png";
const TICK_MS = 5000;

interface ProbeStatus {
  ts: string;
  uptimeSec: number;
  phase: "init" | "running" | "text-mode" | "splash" | "desktop" | "done";
  cpuRunning: boolean;
  instructionCounter: number;
  instructionDelta: number;
  textScreen: string;
  textHash: string;
  gfxW: number;
  gfxH: number;
  dominantColor: string;
  verdict: "" | "SUCCESS" | "FAIL_IOS" | "FAIL_KRNL386" | "FAIL_VXDLINK" | "FAIL_PROTECTION" | "FAIL_SPLASH_HANG" | "FAIL_HUNG" | "FAIL_OTHER";
}

let startTime = 0;
let lastInstr = 0;
let lastTextHash = "";
let stableTextTicks = 0;

// XT scancodes (set 1). Win95 doesn't have Win+R — that landed in Win98.
// Ctrl+Esc opens Start, then R is the underlined mnemonic for "Run...".
const SC = {
  CTRL_DN: [0x1d], CTRL_UP: [0x9d],
  ESC_DN: [0x01], ESC_UP: [0x81],
  R_DN: [0x13], R_UP: [0x93],
  ENTER_DN: [0x1c], ENTER_UP: [0x9c],
  BACKSLASH_DN: [0x2b], BACKSLASH_UP: [0xab],
};

function sendChord(emu: any, ...keys: { dn: number[]; up: number[] }[]) {
  for (const k of keys) emu.keyboard_send_scancodes(k.dn);
  setTimeout(() => {
    for (let i = keys.length - 1; i >= 0; i--) emu.keyboard_send_scancodes(keys[i].up);
  }, 60);
}

function sendKey(emu: any, dn: number[], up: number[]) {
  emu.keyboard_send_scancodes(dn);
  setTimeout(() => emu.keyboard_send_scancodes(up), 50);
}

/** Replay a list of actions: {type:"keys",dn,up} | {type:"text",text} | {type:"wait",ms} */
function runScript(emu: any, steps: any[]) {
  let i = 0;
  const next = () => {
    if (i >= steps.length) { console.log("[probe] script done"); return; }
    const s = steps[i++];
    if (s.type === "wait") { setTimeout(next, s.ms); return; }
    if (s.type === "keys") { sendKey(emu, s.dn, s.up); setTimeout(next, 200); return; }
    if (s.type === "chord") { sendChord(emu, ...s.keys); setTimeout(next, 200); return; }
    if (s.type === "text") {
      // keyboard_send_text handles ASCII → scancode for us
      emu.keyboard_send_text(s.text);
      setTimeout(next, 100 + s.text.length * 30);
      return;
    }
    next();
  };
  next();
}

export function startProbe(emulator: any) {
  startTime = Date.now();
  console.log("[probe] writing to", STATUS_FILE);

  // WIN95_PROBE_SCRIPT=\\HOST  → after desktop, send Win+R, type, Enter
  const scriptCmd = process.env.WIN95_PROBE_SCRIPT;
  let scriptArmed = !!scriptCmd;

  const tick = () => {
    try {
      const s = collectStatus(emulator);
      fs.writeFileSync(STATUS_FILE, JSON.stringify(s, null, 2));

      // Try to capture a screenshot — this can fail if the screen adapter
      // isn't ready yet, so we swallow that.
      try {
        const img: HTMLImageElement = emulator.screen_make_screenshot();
        // The Image has a data: URL src; decode it to bytes
        if (img && img.src && img.src.startsWith("data:image/png;base64,")) {
          const b64 = img.src.slice("data:image/png;base64,".length);
          fs.writeFileSync(SCREEN_FILE, Buffer.from(b64, "base64"));
        }
      } catch {}

      // Once at desktop, fire the keyboard script (once). The 8s settle is
      // for the "Welcome to Windows 95" tip dialog to be dismissable —
      // we send Esc first to clear it.
      if (scriptArmed && s.phase === "desktop" && s.uptimeSec > 8) {
        scriptArmed = false;
        console.log("[probe] desktop detected, running script:", scriptCmd);
        runScript(emulator, [
          { type: "wait", ms: 3000 },
          { type: "keys", dn: SC.ESC_DN, up: SC.ESC_UP },          // dismiss any dialog
          { type: "wait", ms: 1000 },
          { type: "keys", dn: SC.ESC_DN, up: SC.ESC_UP },          // again, for safety
          { type: "wait", ms: 1000 },
          { type: "chord", keys: [
            { dn: SC.CTRL_DN, up: SC.CTRL_UP },
            { dn: SC.ESC_DN, up: SC.ESC_UP },
          ]},                                                       // Ctrl+Esc → Start
          { type: "wait", ms: 1200 },
          { type: "keys", dn: SC.R_DN, up: SC.R_UP },              // Run mnemonic
          { type: "wait", ms: 1000 },
          // keyboard_send_text can't reliably do backslash, so we interleave:
          // scancode for each \ segment, text for each name segment.
          // WIN95_PROBE_SCRIPT='HOST/HOST' → types \\HOST\HOST (we use / as
          // the segment separator in the env var to dodge shell escaping hell)
          ...scriptCmd!.split("/").flatMap((seg, i) => [
            ...(i === 0
              ? [{ type: "keys", dn: SC.BACKSLASH_DN, up: SC.BACKSLASH_UP },
                 { type: "wait", ms: 60 },
                 { type: "keys", dn: SC.BACKSLASH_DN, up: SC.BACKSLASH_UP }]
              : [{ type: "keys", dn: SC.BACKSLASH_DN, up: SC.BACKSLASH_UP }]),
            { type: "wait", ms: 60 },
            { type: "text", text: seg },
            { type: "wait", ms: 100 },
          ]),
          { type: "wait", ms: 400 },
          { type: "keys", dn: SC.ENTER_DN, up: SC.ENTER_UP },
        ]);
      }

      if (s.verdict) {
        console.log("[probe] VERDICT:", s.verdict);
        fs.writeFileSync(STATUS_FILE.replace(".json", ".done"), s.verdict);
      }
    } catch (e) {
      console.log("[probe] tick error:", e);
    }
  };

  tick();
  setInterval(tick, TICK_MS);
}

function collectStatus(emulator: any): ProbeStatus {
  const uptimeSec = (Date.now() - startTime) / 1000;

  // CPU activity — instruction counter is u32 in wasm, wraps every ~4B
  let instr = 0, running = false;
  try { instr = emulator.get_instruction_counter() || 0; } catch {}
  try { running = emulator.is_running(); } catch {}
  const instrDelta = (instr - lastInstr) >>> 0;
  lastInstr = instr;

  // Text screen — only meaningful in text mode (BIOS, DOS, BSOD).
  // In graphics mode this returns garbage or empty.
  let textScreen = "";
  try {
    const screen = emulator.screen_adapter || emulator.v86?.screen_adapter;
    if (screen) {
      const rows = screen.get_text_screen?.() || [];
      textScreen = rows.map((r: string) => r.trimEnd()).join("\n").trim();
    }
  } catch {}

  // VGA state tells us everything: in graphics or text, and at what resolution.
  // Win95 splash: 320×400. Win95 desktop: ≥640×480.
  // Old v86 builds (pre-2025) don't expose screen_width/screen_height — fall
  // back to the rendered canvas dimensions so the bisect harness works across
  // versions.
  let inGraphics = false, gfxW = 0, gfxH = 0;
  try {
    const vga = emulator.v86?.cpu?.devices?.vga;
    if (vga) {
      inGraphics = !!vga.graphical_mode;
      gfxW = vga.screen_width || 0;
      gfxH = vga.screen_height || 0;
    }
  } catch {}
  if (gfxW === 0) {
    try {
      const canvas = document.querySelector("#emulator canvas") as HTMLCanvasElement | null;
      if (canvas && canvas.width > 0) {
        gfxW = canvas.width;
        gfxH = canvas.height;
        // Canvas exists with content → assume graphics. Text mode uses a div.
        const textDiv = document.querySelector("#emulator div") as HTMLElement | null;
        inGraphics = canvas.style.display !== "none" &&
                     (!textDiv || textDiv.style.display === "none");
      }
    } catch {}
  }

  // Sample the framebuffer to identify which screen we're on.
  // Splash is sky-blue gradient (R~120 G~175 B~215). Desktop is teal (0,128,128).
  let dominantColor = "";
  if (inGraphics) {
    try {
      const canvas = document.querySelector("#emulator canvas") as HTMLCanvasElement | null;
      if (canvas) {
        const ctx = canvas.getContext("2d")!;
        const cx = Math.floor(canvas.width / 2);
        const cy = Math.floor(canvas.height / 3); // upper-third → sky on splash, taskbar-free on desktop
        const px = ctx.getImageData(cx, cy, 1, 1).data;
        dominantColor = `${px[0]},${px[1]},${px[2]}`;
      }
    } catch {}
  }

  const textHash = hashStr(textScreen);
  if (!inGraphics && textHash === lastTextHash && textScreen) stableTextTicks++;
  else stableTextTicks = 0;
  lastTextHash = textHash;

  const hasMeaningfulText = !inGraphics && textScreen.length > 20 && /[A-Za-z]{4,}/.test(textScreen);
  const atSplash = inGraphics && gfxW > 0 && gfxW < 640;
  const atDesktop = inGraphics && gfxW >= 640;

  const phase: ProbeStatus["phase"] =
    !running ? "init" :
    atDesktop ? "desktop" :
    atSplash ? "splash" :
    hasMeaningfulText ? "text-mode" :
    "running";

  let verdict: ProbeStatus["verdict"] = "";
  const t = inGraphics ? "" : textScreen.toLowerCase();

  if (t.includes("krnl386")) verdict = "FAIL_KRNL386";
  else if (t.includes("vxd dynamic link")) verdict = "FAIL_VXDLINK";
  else if (t.includes("initializing device ios") && t.includes("protection error")) verdict = "FAIL_IOS";
  else if (t.includes("windows protection error")) verdict = "FAIL_PROTECTION";
  // Stuck at splash for >70s with CPU spinning → IDE IRQ never fired
  else if (atSplash && uptimeSec > 70) verdict = "FAIL_SPLASH_HANG";
  // Stuck on text for 40s
  else if (stableTextTicks >= 8 && instrDelta > 1_000_000) verdict = "FAIL_HUNG";
  // CPU dead
  else if (running && instrDelta < 1000 && uptimeSec > 30) verdict = "FAIL_HUNG";
  // Made it to ≥640×480 graphics → desktop reached. But if a keyboard
  // script is running, hold off — the outer harness reads the SMB log
  // directly and we just keep the app alive.
  else if (atDesktop && uptimeSec > 30 && !process.env.WIN95_PROBE_SCRIPT) verdict = "SUCCESS";
  // Timeout
  else if (uptimeSec > 180) verdict = "FAIL_OTHER";

  return {
    ts: new Date().toISOString(),
    uptimeSec: Math.round(uptimeSec),
    phase, cpuRunning: running,
    instructionCounter: instr,
    instructionDelta: instrDelta,
    textScreen: textScreen.slice(0, 2000),
    textHash, gfxW, gfxH, dominantColor,
    verdict,
  };
}

function hashStr(s: string): string {
  let h = 5381;
  for (let i = 0; i < s.length; i++) h = ((h << 5) + h + s.charCodeAt(i)) | 0;
  return (h >>> 0).toString(16);
}