import { readFile } from "node:fs/promises";
import { resolve, isAbsolute } from "node:path";
import { tmpdir } from "node:os";
import { createRequire } from "node:module";
import { Type } from "typebox";
import { Markdown, Text } from "@mariozechner/pi-tui";
import { getMarkdownTheme, keyHint } from "@mariozechner/pi-coding-agent";
import { type Result, err, ok } from "../util/result";
import { formatBytes } from "../util/truncate";
import { defineBrowserTool, type ToolErr, type ToolOk } from "../util/tool";
import { evalJs } from "./cdp-call";
import { applyTruncation } from "../util/truncate";
import { asNumber, asRecord, asString, isRecord } from "../util/guards";

const COMPACT_PREVIEW_BYTES = 120;

// The AsyncFunction constructor is the documented way to compile user source; a plain `unknown` cast would lose the constructor signature, so this typed cast stays.
const AsyncFunction = Object.getPrototypeOf(async () => {}).constructor as
  new (...args: ReadonlyArray<string>) => (...args: ReadonlyArray<unknown>) => Promise<unknown>;

const requireFromHere = createRequire(import.meta.url);

const ExecuteJsArgs = Type.Object({
  expression: Type.String({ description: "JavaScript expression. `return X` is auto-wrapped in an IIFE." }),
  targetId: Type.Optional(Type.String({ description: "Optional iframe targetId; default = current page." })),
});

export const executeJsTool = defineBrowserTool({
  name: "browser_execute_js",
  label: "Browser Execute JS",
  description:
    "Surgical reads from the DOM. The cheapest, most precise way to extract a specific element's text, attribute, value, or geometry. Prefer over browser_screenshot for ANY data extraction or coordinate lookup. `return X` is auto-wrapped in an IIFE. Always use safeJs / JSON.stringify when interpolating untrusted strings.",
  promptSnippet: "Execute JS in the page — surgical DOM reads (preferred over screenshot)",
  promptGuidelines: [
    "DEFAULT for extracting a specific value: `document.querySelector('.price').innerText`, `input.value`, `el.getAttribute('aria-label')`, etc.",
    "For click coordinates not already in browser_snapshot: `JSON.stringify(document.querySelector('SELECTOR').getBoundingClientRect())` — beats a screenshot every time.",
    "For 'is this element visible / enabled / checked / focused', a one-liner here beats a screenshot every time.",
    "DO NOT call browser_screenshot to read a value or check element state. Use this tool.",
    "`return foo` is auto-wrapped in an IIFE — both `foo` and `(() => foo)()` work.",
    "For iframes, first run `Object.values(document.querySelectorAll('iframe'))` to find the iframe, then pass its targetId.",
    "Result must be JSON-serializable (Runtime.evaluate returnByValue=true).",
  ],
  parameters: ExecuteJsArgs,
  concurrency: "parallel",
  async handler(args, { client }): Promise<Result<ToolOk, ToolErr>> {
    const r = await evalJs(client, args.expression, args.targetId);
    if (!r.success) return r;
    const valueStr = r.data === undefined ? "undefined" : JSON.stringify(r.data);
    const truncated = await applyTruncation(valueStr, "js");
    let pretty: string | undefined;
    try {
      const parsed: unknown = JSON.parse(valueStr);
      pretty = JSON.stringify(parsed, null, 2);
    } catch {
      pretty = undefined;
    }
    return ok({
      text: truncated.text,
      details: {
        valueLength: valueStr.length,
        full: valueStr.length > 200_000 ? valueStr.slice(0, 200_000) : valueStr,
        ...(pretty !== undefined ? { pretty: pretty.length > 200_000 ? pretty.slice(0, 200_000) : pretty } : {}),
        ...(truncated.fullOutputPath !== undefined ? { fullOutputPath: truncated.fullOutputPath } : {}),
      },
    });
  },

  renderResult(result, expanded, theme) {
    const raw = asRecord(result.details);
    if (raw === undefined) return new Text(theme.fg("error", "execute_js: no details"), 0, 0);
    const details = {
      valueLength: asNumber(raw["valueLength"]),
      full: asString(raw["full"]),
      pretty: asString(raw["pretty"]),
      fullOutputPath: asString(raw["fullOutputPath"]),
    };

    const len = details.valueLength ?? 0;
    const full = details.full ?? "";
    const isJson = details.pretty !== undefined;

    if (!expanded) {
      const preview = full.length > COMPACT_PREVIEW_BYTES ? full.slice(0, COMPACT_PREVIEW_BYTES) + "…" : full;
      const md = [
        `**${formatBytes(len)}** ${isJson ? "JSON" : "value"}`,
        "```",
        preview,
        "```",
        keyHint("app.tools.expand", "to expand"),
      ].join("\n");
      return new Markdown(md, 0, 0, getMarkdownTheme());
    }

    const body = details.pretty ?? full;
    const fence = isJson ? "```json" : "```";
    const tail = details.fullOutputPath
      ? `\n\nFull value at \`${details.fullOutputPath}\` · ${keyHint("app.tools.expand", "to collapse")}`
      : `\n\n${keyHint("app.tools.expand", "to collapse")}`;
    const md = [`**${formatBytes(len)}** ${isJson ? "JSON" : "value"}`, fence, body, "```", tail].join("\n");
    return new Markdown(md, 0, 0, getMarkdownTheme());
  },
});

const RunScriptArgs = Type.Object({
  path: Type.String({ description: "Absolute path to the script file (.js or .mjs)" }),
  params: Type.Optional(
    Type.Object({}, { additionalProperties: true, description: "Args passed to the script as `params`" }),
  ),
  timeoutMs: Type.Optional(
    Type.Integer({
      default: 60_000,
      minimum: 100,
      maximum: 600_000,
      description: "Hard timeout in ms. Default 60s, max 600s.",
    }),
  ),
});

const allowedRoots = (): ReadonlyArray<string> => {
  const env = process.env["BH_SCRIPT_DIR"];
  return [tmpdir(), process.cwd(), ...(env !== undefined ? [env] : [])].map((d) => resolve(d));
};

const isPathAllowed = (p: string): boolean => {
  const abs = resolve(p);
  return allowedRoots().some((root) => abs === root || abs.startsWith(`${root}/`));
};

const MAX_SOURCE_BYTES = 1_000_000;

type ContentItem = { readonly type: "text"; readonly text: string };

const isContentItem = (v: unknown): v is ContentItem =>
  isRecord(v) && v["type"] === "text" && typeof v["text"] === "string";

export const runScriptTool = defineBrowserTool({
  name: "browser_run_script",
  label: "Browser Run Script",
  description:
    "Execute a temporary JavaScript script with full Node.js + browser-daemon access. Path must be inside tmpdir, cwd, or BH_SCRIPT_DIR. Mandatory timeout. The script is full RCE on the harness's process — only invoke scripts you wrote and reviewed.",
  promptSnippet: "Run a temporary script with daemon + Node access (security-bounded)",
  promptGuidelines: [
    "Write the script with the write tool first; pass its absolute path.",
    "Path must be inside tmpdir, cwd, or BH_SCRIPT_DIR — otherwise rejected.",
    "Default timeout is 60s; pass timeoutMs to extend (max 600s).",
    "Script bindings: params, daemon, require, signal, onUpdate, ctx, console, fetch, JSON, Buffer, setTimeout, clearTimeout.",
    "Script MUST return { content: [{ type: 'text', text: '...' }], details?: {...} }. Throw on errors.",
  ],
  parameters: RunScriptArgs,
  concurrency: "parallel",
  async handler(args, { client, signal, onUpdate, extensionCtx }): Promise<Result<ToolOk, ToolErr>> {
    if (!isAbsolute(args.path)) {
      return err({ kind: "invalid_state", message: "Script path must be absolute" });
    }
    if (!isPathAllowed(args.path)) {
      return err({
        kind: "invalid_state",
        message: `Script path outside allowed directories (allowed: ${allowedRoots().join(", ")})`,
      });
    }
    let source: string;
    try {
      source = await readFile(args.path, "utf8");
    } catch (e) {
      return err({
        kind: "io_error",
        message: `Failed to read script: ${e instanceof Error ? e.message : String(e)}`,
      });
    }
    if (source.length === 0) return err({ kind: "invalid_state", message: "Script is empty" });
    if (source.length > MAX_SOURCE_BYTES) {
      return err({ kind: "invalid_state", message: `Script exceeds ${MAX_SOURCE_BYTES}B size cap` });
    }

    let executeFn: (...a: ReadonlyArray<unknown>) => Promise<unknown>;
    try {
      executeFn = new AsyncFunction(
        "params", "daemon", "require", "signal", "onUpdate", "ctx",
        "console", "fetch", "JSON", "Buffer", "setTimeout", "clearTimeout",
        `"use strict";\n${source}`,
      );
    } catch (e) {
      return err({
        kind: "invalid_state",
        message: `Syntax error: ${e instanceof Error ? e.message : String(e)}`,
      });
    }

    const timeoutMs = args.timeoutMs ?? 60_000;
    const ac = new AbortController();
    const onAbort = (): void => ac.abort();
    if (signal !== undefined) signal.addEventListener("abort", onAbort, { once: true });
    const timeoutTimer = setTimeout(() => ac.abort(), timeoutMs);

    try {
      const scriptPromise = executeFn(
        args.params ?? {},
        client,
        requireFromHere,
        ac.signal,
        (u: unknown) => {
          if (!isRecord(u)) return;
          const content = u["content"];
          if (!Array.isArray(content) || content.length === 0) return;
          const first: unknown = content[0];
          if (!isRecord(first)) return;
          const txt = first["text"];
          if (typeof txt !== "string") return;
          try { onUpdate({ text: txt }); } catch {}
        },
        extensionCtx ?? { cwd: process.cwd() },
        console, fetch, JSON, Buffer, setTimeout, clearTimeout,
      );
      const abortPromise = new Promise<never>((_, reject) => {
        ac.signal.addEventListener("abort", () => reject(new Error("script aborted (timeout or cancellation)")), { once: true });
      });
      const result = await Promise.race([scriptPromise, abortPromise]);
      clearTimeout(timeoutTimer);
      if (signal !== undefined) signal.removeEventListener("abort", onAbort);

      if (!isRecord(result)) {
        return err({ kind: "invalid_state", message: `Script must return an object; got ${JSON.stringify(result)}` });
      }
      const content = result["content"];
      if (!Array.isArray(content)) {
        return err({ kind: "invalid_state", message: "Script return value must have a content array" });
      }
      if (!content.every(isContentItem)) {
        return err({ kind: "invalid_state", message: "Script content array must contain { type: 'text', text: string } items" });
      }
      const textOut = content.map((c) => c.text).join("\n");
      const details = result["details"];
      return isRecord(details) ? ok({ text: textOut, details }) : ok({ text: textOut });
    } catch (e) {
      clearTimeout(timeoutTimer);
      if (signal !== undefined) signal.removeEventListener("abort", onAbort);
      return err({
        kind: "internal",
        message: `Script execution failed: ${e instanceof Error ? e.message : String(e)}`,
      });
    }
  },
});