#!/usr/bin/env node
// Drive the Emscripten build in a real headless Chromium using .snap scripts.
// Shared commands retain test/snapshot.zig's spelling and output format:
//   wait <ms> <text> | stable <quiet-ms> <timeout-ms>
//   snap <label> | snapstyle <label>
// Browser touch additions:
//   touch <down|move|up> <id> <col> <row>
//   swipe <id> <from-col> <from-row> <to-col> <to-row> <steps>
//
// No npm package is needed: Node's WebSocket connects directly to Chrome's
// DevTools protocol. Set PARDES_CHROME when Chromium is not on PATH or in the
// normal Playwright cache.
import childProcess from "node:child_process";
import fs from "node:fs";
import fsp from "node:fs/promises";
import http from "node:http";
import net from "node:net";
import os from "node:os";
import path from "node:path";

const VIEWPORT = { width: 1120, height: 720 };
const args = process.argv.slice(2);
const update = args.includes("--update");
const positional = args.filter((arg) => arg !== "--update");
if (positional.length !== 2) {
    console.error("usage: node test/web_snapshot.mjs <zig-out/web> <script.snap> [--update]");
    process.exit(2);
}

const webDir = path.resolve(positional[0]);
const scriptPath = path.resolve(positional[1]);
const goldenPath = scriptPath.replace(/\.snap$/, ".golden");
if (goldenPath === scriptPath) throw new Error(`not a .snap path: ${scriptPath}`);

let server;
let chrome;
let client;
let userDataDir;
let chromeStderr = "";
const browserLog = [];

async function main() {
  try {
    const served = await serveDirectory(webDir);
    server = served.server;
    const debugPort = await unusedPort();
    const chromePath = await findChrome();
    userDataDir = await fsp.mkdtemp(path.join(os.tmpdir(), "pardes-web-snap-"));
    chrome = childProcess.spawn(chromePath, [
        "--headless=new",
        "--no-sandbox",
        "--disable-dev-shm-usage",
        "--enable-unsafe-swiftshader",
        "--use-angle=swiftshader",
        "--no-first-run",
        "--no-default-browser-check",
        `--remote-debugging-address=127.0.0.1`,
        `--remote-debugging-port=${debugPort}`,
        `--user-data-dir=${userDataDir}`,
        "about:blank",
    ], { stdio: ["ignore", "ignore", "pipe"] });
    chrome.stderr.setEncoding("utf8");
    chrome.stderr.on("data", (chunk) => {
        chromeStderr = (chromeStderr + chunk).slice(-16_384);
    });

    await waitForDevTools(debugPort, chrome);
    const targetResponse = await fetch(
        `http://127.0.0.1:${debugPort}/json/new?${encodeURIComponent(`http://127.0.0.1:${served.port}/index.html`)}`,
        { method: "PUT" },
    );
    if (!targetResponse.ok) throw new Error(`create Chrome target: HTTP ${targetResponse.status}`);
    const target = await targetResponse.json();
    client = await Cdp.connect(target.webSocketDebuggerUrl, browserLog);
    await client.send("Runtime.enable");
    await client.send("Page.enable");
    await client.send("Log.enable");
    await client.send("Emulation.setDeviceMetricsOverride", {
        ...VIEWPORT,
        screenWidth: VIEWPORT.width,
        screenHeight: VIEWPORT.height,
        deviceScaleFactor: 1,
        mobile: false,
    });
    await client.send("Emulation.setTouchEmulationEnabled", { enabled: true, maxTouchPoints: 1 });
    await waitForRuntime(20_000);

    const output = await runScript(await fsp.readFile(scriptPath, "utf8"));
    if (update) {
        await fsp.writeFile(goldenPath, output);
        console.error(`updated ${path.relative(process.cwd(), goldenPath)}`);
    } else {
        const golden = await fsp.readFile(goldenPath, "utf8").catch(() => null);
        if (golden === null) throw new Error(`missing ${goldenPath}; run with --update`);
        if (golden !== output) {
            const actualPath = goldenPath.replace(/\.golden$/, ".actual");
            await fsp.writeFile(actualPath, output);
            throw new Error(`snapshot mismatch; actual written to ${actualPath}`);
        }
        console.error(`web snapshot ok: ${path.relative(process.cwd(), scriptPath)}`);
    }
  } catch (error) {
    console.error(error?.stack ?? error);
    if (browserLog.length) console.error(`browser log:\n${browserLog.join("\n")}`);
    if (chromeStderr.trim()) console.error(`chromium stderr (tail):\n${chromeStderr.trim()}`);
    process.exitCode = 1;
  } finally {
    client?.close();
    if (chrome && chrome.exitCode === null) {
        chrome.kill("SIGTERM");
        await Promise.race([
            new Promise((resolve) => chrome.once("exit", resolve)),
            delay(2_000),
        ]);
    }
    if (server) await new Promise((resolve) => server.close(resolve));
    if (userDataDir) await fsp.rm(userDataDir, { recursive: true, force: true, maxRetries: 5, retryDelay: 100 });
  }
}

async function runScript(source) {
    let output = "";
    let activeTouch = null;
    const lines = source.split("\n");
    for (let index = 0; index < lines.length; index += 1) {
        const line = lines[index].trim();
        if (!line || line.startsWith("#")) continue;
        const tokens = line.split(/\s+/);
        const command = tokens.shift();
        try {
            if (command === "wait") {
                const timeout = integer(tokens.shift(), "wait timeout");
                const needle = tokens.join(" ");
                if (!needle) throw new Error("wait needs text");
                await waitUntil(async () => (await grid()).text.includes(needle), timeout, `screen containing ${JSON.stringify(needle)}`);
            } else if (command === "stable") {
                const quiet = integer(tokens.shift(), "stable quiet time");
                const timeout = integer(tokens.shift(), "stable timeout");
                await waitStable(quiet, timeout);
            } else if (command === "snap") {
                const label = tokens.join(" ");
                if (!label) throw new Error("snap needs a label");
                output += formatSnapshot(label, await grid());
            } else if (command === "snapstyle") {
                const label = tokens.join(" ");
                if (!label) throw new Error("snapstyle needs a label");
                output += formatStyleSnapshot(label, await grid());
            } else if (command === "touch") {
                const phase = tokens.shift();
                const id = integer(tokens.shift(), "touch id");
                const col = number(tokens.shift(), "touch col");
                const row = number(tokens.shift(), "touch row");
                if (tokens.length || !["down", "move", "up"].includes(phase)) throw new Error("bad touch command");
                activeTouch = await dispatchTouch(phase, id, col, row, activeTouch);
                await delay(40);
            } else if (command === "swipe") {
                const id = integer(tokens.shift(), "swipe id");
                const x0 = number(tokens.shift(), "swipe start col");
                const y0 = number(tokens.shift(), "swipe start row");
                const x1 = number(tokens.shift(), "swipe end col");
                const y1 = number(tokens.shift(), "swipe end row");
                const steps = integer(tokens.shift(), "swipe steps");
                if (tokens.length || steps < 1) throw new Error("bad swipe command");
                activeTouch = await dispatchTouch("down", id, x0, y0, activeTouch);
                for (let step = 1; step <= steps; step += 1) {
                    const t = step / steps;
                    activeTouch = await dispatchTouch("move", id, x0 + (x1 - x0) * t, y0 + (y1 - y0) * t, activeTouch);
                    await delay(20);
                }
                activeTouch = await dispatchTouch("up", id, x1, y1, activeTouch);
                await delay(80);
            } else {
                throw new Error(`unknown command ${command}`);
            }
        } catch (error) {
            const screen = await grid().catch(() => null);
            const detail = screen ? `\ncurrent screen:\n${screen.lines.map((row) => `|${row}`).join("\n")}` : "";
            throw new Error(`${path.basename(scriptPath)}:${index + 1}: ${line}\n${error.message}${detail}`, { cause: error });
        }
    }
    if (activeTouch) throw new Error("script ended with a finger still down");
    return output;
}

async function dispatchTouch(phase, id, col, row, active) {
    const point = await evaluate(`({
        x: Module._pardes_web_test_cell_x(${JSON.stringify(col)}),
        y: Module._pardes_web_test_cell_y(${JSON.stringify(row)})
    })`);
    const touch = { x: point.x, y: point.y, id, radiusX: 1, radiusY: 1, force: 1 };
    if (phase === "down") {
        if (active) throw new Error("only one finger is supported by this web test");
        await client.send("Input.dispatchTouchEvent", { type: "touchStart", touchPoints: [touch] });
        return touch;
    }
    if (!active || active.id !== id) throw new Error(`finger ${id} is not down`);
    if (phase === "move") {
        await client.send("Input.dispatchTouchEvent", { type: "touchMove", touchPoints: [touch] });
        return touch;
    }
    // Chrome's touchEnd carries no points; a final move gives SDL the scripted
    // release coordinate before the lift.
    await client.send("Input.dispatchTouchEvent", { type: "touchMove", touchPoints: [touch] });
    await client.send("Input.dispatchTouchEvent", { type: "touchEnd", touchPoints: [] });
    return null;
}

async function grid() {
    return evaluate(`(() => {
        const cols = Module._pardes_web_test_cols();
        const rows = Module._pardes_web_test_rows();
        const lines = [];
        const styleRows = [];
        for (let y = 0; y < rows; y++) {
            let line = "";
            const styles = [];
            for (let x = 0; x < cols; x++) {
                const cp = Module._pardes_web_test_cell(x, y) || 32;
                line += String.fromCodePoint(cp);
                styles.push([
                    Module._pardes_web_test_cell_fg(x, y),
                    Module._pardes_web_test_cell_bg(x, y),
                    Module._pardes_web_test_cell_attrs(x, y),
                ]);
            }
            lines.push(line.replace(/ +$/, ""));
            styleRows.push(styles);
        }
        return {
            cols, rows, lines, styleRows,
            cursorX: Module._pardes_web_test_cursor_x(),
            cursorY: Module._pardes_web_test_cursor_y(),
            text: lines.join("\\n"),
        };
    })()`);
}

function formatSnapshot(label, state) {
    const cursorX = state.cursorX < 0 ? 0 : state.cursorX;
    const cursorY = state.cursorY < 0 ? 0 : state.cursorY;
    let out = `== snap ${label} grid=${state.cols}x${state.rows} cursor=${cursorX},${cursorY}\n`;
    for (const line of state.lines) out += `|${line}\n`;
    return out;
}

function formatStyleSnapshot(label, state) {
    let out = `== style ${label}\n`;
    for (let y = 0; y < state.rows; y++) {
        const styles = state.styleRows[y];
        out += `|${y}:`;
        let runStart = 0;
        let runKey = styleKey(styles[0]);
        for (let x = 1; x <= state.cols; x++) {
            const key = x === state.cols ? null : styleKey(styles[x]);
            if (key === runKey) continue;
            out += ` ${runStart}-${x - 1} ${runKey}`;
            runStart = x;
            runKey = key;
        }
        out += "\n";
    }
    return out;
}

function styleKey([fg, bg, attrs]) {
    return `${colorKey(fg)},${colorKey(bg)},${attrsKey(attrs)}`;
}

function colorKey(color) {
    if (color === 0x01000000) return "d";
    if ((color & 0xff000000) === 0x02000000) return `p${color & 0xff}`;
    return `#${(color & 0xffffff).toString(16).padStart(6, "0")}`;
}

function attrsKey(attrs) {
    let out = "";
    if (attrs & (1 << 0)) out += "b";
    if (attrs & (1 << 1)) out += "f";
    if (attrs & (1 << 2)) out += "i";
    if (attrs & (1 << 3)) out += "k";
    if (attrs & (1 << 4)) out += "r";
    if (attrs & (1 << 5)) out += "v";
    if (attrs & (1 << 6)) out += "x";
    out += ["", "u", "U", "~", ".", "-"][(attrs >> 8) & 0x7] ?? "?";
    return out;
}

async function waitStable(quiet, timeout) {
    let elapsed = 0;
    let previous = JSON.stringify(await grid());
    while (elapsed < timeout) {
        await delay(quiet);
        elapsed += quiet;
        const current = JSON.stringify(await grid());
        if (current === previous) return;
        previous = current;
    }
    throw new Error(`screen did not stabilize within ${timeout}ms`);
}

async function waitForRuntime(timeout) {
    await waitUntil(async () => {
        try {
            return await evaluate(`typeof Module?._pardes_web_test_cols === "function" && Module._pardes_web_test_cols() > 0`);
        } catch {
            return false;
        }
    }, timeout, "Pardes web runtime");
}

async function waitUntil(predicate, timeout, description) {
    const deadline = Date.now() + timeout;
    while (Date.now() < deadline) {
        if (await predicate()) return;
        if (chrome?.exitCode !== null) throw new Error(`Chromium exited with ${chrome.exitCode}`);
        await delay(50);
    }
    throw new Error(`timed out waiting for ${description}`);
}

async function evaluate(expression) {
    const response = await client.send("Runtime.evaluate", {
        expression,
        returnByValue: true,
        awaitPromise: true,
    });
    if (response.exceptionDetails) throw new Error(response.exceptionDetails.text);
    return response.result.value;
}

class Cdp {
    static async connect(url, log) {
        const socket = new WebSocket(url);
        await new Promise((resolve, reject) => {
            socket.addEventListener("open", resolve, { once: true });
            socket.addEventListener("error", () => reject(new Error(`connect DevTools websocket ${url}`)), { once: true });
        });
        return new Cdp(socket, log);
    }

    constructor(socket, log) {
        this.socket = socket;
        this.log = log;
        this.nextId = 1;
        this.pending = new Map();
        socket.addEventListener("message", (event) => {
            const message = JSON.parse(event.data);
            if (message.id) {
                const pending = this.pending.get(message.id);
                if (!pending) return;
                this.pending.delete(message.id);
                if (message.error) pending.reject(new Error(`${pending.method}: ${message.error.message}`));
                else pending.resolve(message.result ?? {});
                return;
            }
            if (message.method === "Runtime.exceptionThrown")
                log.push(`exception: ${message.params.exceptionDetails.text}`);
            else if (message.method === "Runtime.consoleAPICalled")
                log.push(`console ${message.params.type}: ${message.params.args.map((arg) => arg.value ?? arg.description).join(" ")}`);
            else if (message.method === "Log.entryAdded")
                log.push(`${message.params.entry.level}: ${message.params.entry.text}`);
        });
    }

    send(method, params = {}) {
        const id = this.nextId++;
        return new Promise((resolve, reject) => {
            this.pending.set(id, { resolve, reject, method });
            this.socket.send(JSON.stringify({ id, method, params }));
        });
    }

    close() {
        this.socket.close();
    }
}

async function serveDirectory(root) {
    const canonicalRoot = await fsp.realpath(root);
    const server = http.createServer(async (request, response) => {
        try {
            const url = new URL(request.url, "http://localhost");
            const relative = decodeURIComponent(url.pathname === "/" ? "/index.html" : url.pathname);
            const filename = path.resolve(canonicalRoot, `.${relative}`);
            if (filename !== canonicalRoot && !filename.startsWith(`${canonicalRoot}${path.sep}`)) {
                response.writeHead(403).end();
                return;
            }
            const contents = await fsp.readFile(filename);
            const contentType = filename.endsWith(".wasm") ? "application/wasm"
                : filename.endsWith(".js") ? "text/javascript; charset=utf-8"
                    : "text/html; charset=utf-8";
            response.writeHead(200, { "content-type": contentType, "cache-control": "no-store" });
            response.end(contents);
        } catch {
            response.writeHead(404).end();
        }
    });
    await new Promise((resolve, reject) => {
        server.once("error", reject);
        server.listen(0, "127.0.0.1", resolve);
    });
    return { server, port: server.address().port };
}

async function unusedPort() {
    const probe = net.createServer();
    await new Promise((resolve, reject) => {
        probe.once("error", reject);
        probe.listen(0, "127.0.0.1", resolve);
    });
    const port = probe.address().port;
    await new Promise((resolve) => probe.close(resolve));
    return port;
}

async function waitForDevTools(port, child) {
    const deadline = Date.now() + 10_000;
    while (Date.now() < deadline) {
        if (child.exitCode !== null) throw new Error(`Chromium exited with ${child.exitCode}`);
        try {
            const response = await fetch(`http://127.0.0.1:${port}/json/version`);
            if (response.ok) return;
        } catch {}
        await delay(50);
    }
    throw new Error("Chromium DevTools endpoint did not start");
}

async function findChrome() {
    const candidates = [];
    if (process.env.PARDES_CHROME) candidates.push(process.env.PARDES_CHROME);
    for (const command of ["chromium", "chromium-browser", "google-chrome", "google-chrome-stable"]) {
        const found = childProcess.spawnSync("which", [command], { encoding: "utf8" });
        if (found.status === 0 && found.stdout.trim()) candidates.push(found.stdout.trim());
    }
    const cache = process.env.PLAYWRIGHT_BROWSERS_PATH || path.join(os.homedir(), ".cache", "ms-playwright");
    for (const entry of await fsp.readdir(cache).catch(() => [])) {
        if (entry.startsWith("chromium-")) {
            candidates.push(path.join(cache, entry, "chrome-linux64", "chrome"));
            candidates.push(path.join(cache, entry, "chrome-linux", "chrome"));
        } else if (entry.startsWith("chromium_headless_shell-")) {
            candidates.push(path.join(cache, entry, "chrome-headless-shell-linux64", "chrome-headless-shell"));
        }
    }
    for (const candidate of candidates) {
        try {
            await fsp.access(candidate, fs.constants.X_OK);
            return candidate;
        } catch {}
    }
    throw new Error("no Chromium found; set PARDES_CHROME=/path/to/chrome");
}

function integer(value, label) {
    const parsed = Number.parseInt(value, 10);
    if (!Number.isSafeInteger(parsed) || String(parsed) !== value) throw new Error(`bad ${label}: ${value}`);
    return parsed;
}

function number(value, label) {
    const parsed = Number(value);
    if (!Number.isFinite(parsed)) throw new Error(`bad ${label}: ${value}`);
    return parsed;
}

function delay(ms) {
    return new Promise((resolve) => setTimeout(resolve, ms));
}

await main();