#!/usr/bin/env node
'use strict';

/*
 * run.js — the harness behind `Gral.run`.
 *
 * Given a prompt for a target agent it:
 *   1. Resolves the `read` / `write` permission scopes.
 *   2. Collects the `open` files and directories as prompt context.
 *   3. Assembles the tool specs from `tools` + `defaultTools`.
 *   4. Runs the prompt/tool-call loop: send the prompt, execute any tool
 *      calls locally, feed the results back, repeat until the agent
 *      returns a plain response.
 */

import * as fs from 'fs';
import * as path from 'path';

const MAX_READ_BYTES = 1024;
const MAX_ITERATIONS = 20;

/* ------------------------------------------------------------------ *
 * Scopes / permissions
 * ------------------------------------------------------------------ */

/**
 * Normalize a scope descriptor into an absolute allow-list.
 *
 *   null | true        -> null  (allow everything)
 *   false | []         -> []    (allow nothing)
 *   [entry, ...]       -> resolved absolute paths
 *
 * @param {?boolean|string[]} scope
 * @param {string} root
 * @returns {?string[]}
 */
function resolveScope(scope, root) {
  if (scope === true || scope === null || scope === undefined) return null;
  if (!Array.isArray(scope)) return [];
  return scope.map((entry) => path.resolve(root, entry));
}

/**
 * True when `target` is equal to or nested beneath an allowed path.
 * A `null` allow-list grants unrestricted access.
 */
function isAllowed(target, allowed) {
  if (allowed === null || allowed === undefined) return true;
  return allowed.some(
    (base) => target === base || target.startsWith(base + path.sep)
  );
}

/* ------------------------------------------------------------------ *
 * Default tool handlers
 *
 * Every handler receives the parsed call `args` and a context of
 * `{root, scope}`; the scope is the resolved allow-list for the tool.
 * ------------------------------------------------------------------ */

function readFile(args, { root, scope }) {
  const file = args.path;
  const abs = path.resolve(root, file);
  if (!isAllowed(abs, scope)) throw new Error(`read denied: ${file}`);

  let lines = fs.readFileSync(abs, 'utf8').split('\n');
  const from = args.lineStart != null ? args.lineStart - 1 : 0;
  const to = args.lineEnd != null ? args.lineEnd : lines.length;
  lines = lines.slice(from, to);

  let content = lines.join('\n');
  const bytes = Buffer.from(content, 'utf8');
  if (bytes.length > MAX_READ_BYTES) {
    content = bytes.slice(0, MAX_READ_BYTES).toString('utf8');
  }
  return content;
}

function writeFile(args, { root, scope }) {
  const file = args.path;
  const abs = path.resolve(root, file);
  if (!isAllowed(abs, scope)) throw new Error(`write denied: ${file}`);

  fs.mkdirSync(path.dirname(abs), { recursive: true });
  fs.writeFileSync(abs, args.content ?? '');
  return `wrote ${file}`;
}

function updateFile(args, { root, scope }) {
  const file = args.path;
  const abs = path.resolve(root, file);
  if (!isAllowed(abs, scope)) throw new Error(`write denied: ${file}`);

  const content = fs.readFileSync(abs, 'utf8');
  const search = args.search;
  const replace = args.replace ?? '';

  let updated;
  if (args.global) {
    updated = content.split(search).join(replace);
  } else {
    const at = content.indexOf(search);
    updated =
      at < 0
        ? content
        : content.slice(0, at) + replace + content.slice(at + search.length);
  }
  fs.writeFileSync(abs, updated);
  return `updated ${file}`;
}

function listDir(args, { root, scope }) {
  const dir = args.path || '.';
  const abs = path.resolve(root, dir);
  if (!isAllowed(abs, scope)) throw new Error(`read denied: ${dir}`);

  return fs
    .readdirSync(abs, { withFileTypes: true })
    .map((entry) => (entry.isDirectory() ? `${entry.name}/` : entry.name));
}

/* ------------------------------------------------------------------ *
 * Default tools, keyed by name
 * ------------------------------------------------------------------ */

const DEFAULT_TOOLS = {
  'read-file': {
    scope: 'read',
    handler: readFile,
    description: 'Read a file.',
    parameters: {
      type: 'object',
      properties: {
        path: { type: 'string' },
        lineStart: { type: 'number' },
        lineEnd: { type: 'number' },
      },
      required: ['path'],
    },
  },
  'write-file': {
    scope: 'write',
    handler: writeFile,
    description: 'Write the entire content of a file.',
    parameters: {
      type: 'object',
      properties: {
        path: { type: 'string' },
        content: { type: 'string' },
      },
      required: ['path', 'content'],
    },
  },
  'update-file': {
    scope: 'write',
    handler: updateFile,
    description: 'Replace `search` with `replace` in a file.',
    parameters: {
      type: 'object',
      properties: {
        path: { type: 'string' },
        search: { type: 'string' },
        replace: { type: 'string' },
        global: { type: 'boolean' },
      },
      required: ['path', 'search'],
    },
  },
  'list-dir': {
    scope: 'read',
    handler: listDir,
    description: 'List a directory. Directories are suffixed with "/".',
    parameters: {
      type: 'object',
      properties: {
        path: { type: 'string' },
      },
      required: [],
    },
  },
};

/**
 * Resolve the `defaultTools` selection to a list of default tool names.
 * `null` / `true` select every default; `false` / `[]` select none.
 */
function selectDefaults(selection) {
  if (selection === true || selection === null || selection === undefined) {
    return Object.keys(DEFAULT_TOOLS);
  }
  if (!Array.isArray(selection)) return [];
  return selection.filter((name) => name in DEFAULT_TOOLS);
}

/**
 * Assemble the tool bundle: selected defaults plus any custom `tools`.
 * A custom tool whose name matches a default overrides it.
 */
function buildTools({ read, write, tools, defaultTools }) {
  const bundle = [];

  for (const name of selectDefaults(defaultTools)) {
    const def = DEFAULT_TOOLS[name];
    bundle.push({
      name,
      description: def.description,
      parameters: def.parameters,
      scope: def.scope === 'read' ? read : write,
      handler: def.handler,
    });
  }

  if (Array.isArray(tools)) {
    for (const tool of tools) {
      if (!tool || !tool.name) continue;
      const idx = bundle.findIndex((t) => t.name === tool.name);
      if (idx >= 0) bundle[idx] = tool;
      else bundle.push(tool);
    }
  }

  return bundle;
}

/**
 * Build a name -> execution function for the bundle. Unknown tools and
 * handler failures are reported as tool-result strings rather than thrown,
 * so the loop can hand them back to the agent.
 */
function makeExecutor(bundle, root) {
  const byName = new Map(bundle.map((tool) => [tool.name, tool]));

  return function execute(name, args) {
    const tool = byName.get(name);
    if (!tool) return `Error: unknown tool '${name}'`;
    if (typeof tool.handler !== 'function') {
      return `Error: tool '${name}' has no handler`;
    }
    try {
      return tool.handler(args || {}, { root, scope: tool.scope });
    } catch (err) {
      return `Error: ${err.message}`;
    }
  };
}

/* ------------------------------------------------------------------ *
 * Open context
 * ------------------------------------------------------------------ */

/**
 * Read the `open` entries as prompt context. Files carry their content,
 * directories carry a listing. Entries outside the read scope are skipped.
 */
function collectContext(open, root, read) {
  if (open == null || open === false) return [];

  const entries = open === true ? ['.'] : Array.isArray(open) ? open : [open];
  const context = [];

  for (const entry of entries) {
    const abs = path.resolve(root, entry);
    if (!isAllowed(abs, read)) continue;

    let stat;
    try {
      stat = fs.statSync(abs);
    } catch (err) {
      continue;
    }

    if (stat.isDirectory()) {
      const listing = fs
        .readdirSync(abs, { withFileTypes: true })
        .map((e) => (e.isDirectory() ? `${e.name}/` : e.name));
      context.push({ path: entry, type: 'dir', content: listing.join('\n') });
    } else {
      context.push({
        path: entry,
        type: 'file',
        content: fs.readFileSync(abs, 'utf8'),
      });
    }
  }

  return context;
}

function formatContext(context) {
  return context
    .map((entry) =>
      entry.type === 'dir'
        ? `Directory: ${entry.path}\n${entry.content}`
        : `File: ${entry.path}\n${entry.content}`
    )
    .join('\n\n---\n\n');
}

/* ------------------------------------------------------------------ *
 * Tool-call extraction
 * ------------------------------------------------------------------ */

/**
 * Normalize the tool calls returned by the prompt action. Accepts either
 * a flat `{id, name, arguments}` shape or a nested `{id, function:{...}}`
 * shape, and parses string `arguments` as JSON.
 */
function extractToolCalls(res) {
  const raw = res && (res.toolCalls || res.tool_calls);
  if (!Array.isArray(raw)) return [];

  return raw.map((call) => {
    const fn = call.function || call;
    let args = call.arguments !== undefined ? call.arguments : fn.arguments;
    if (typeof args === 'string') {
      try {
        args = JSON.parse(args);
      } catch (err) {
        args = {};
      }
    }
    return { id: call.id, name: fn.name, args: args || {} };
  });
}

/* ------------------------------------------------------------------ *
 * Run
 * ------------------------------------------------------------------ */

/**
 * The harness behind `Gral.run`. Sends a prompt to a target agent with a
 * tool bundle restricted by the supplied arguments, then loops: while the
 * agent returns tool calls, execute them locally and send the results
 * back until a plain response is produced.
 *
 * @param {object} options
 * @param {string} options.agentId     Target agent for the prompt.
 * @param {string} [options.instruction] Instruction for the agent.
 * @param {string} [options.input]       Main input for the agent.
 * @param {object[]} [options.messages]  Prior messages for the agent.
 * @param {?boolean|string[]} [options.read]  Readable files/dirs (null = all).
 * @param {?boolean|string[]} [options.write] Writable files/dirs (null = all).
 * @param {?boolean|string[]} [options.open]  Paths opened as context.
 * @param {object[]} [options.tools]          Extra tools to pass the agent.
 * @param {?boolean|string[]} [options.defaultTools] Default tool selection.
 * @returns {Promise<any>} The agent's final response.
 */
async function run({
  agentId,
  instruction,
  input,
  messages,
  read = null,
  write = null,
  open = null,
  tools = null,
  defaultTools = true,
} = {}) {
  const Gral = global.Gral;
  const root = Gral && Gral.path ? Gral.path : process.cwd();

  if (!agentId) throw new Error('run: agentId is required');
  if (!Gral || !Gral.horde) throw new Error('run: horde connection unavailable');

  const readScope = resolveScope(read, root);
  const writeScope = resolveScope(write, root);

  const bundle = buildTools({
    read: readScope,
    write: writeScope,
    tools,
    defaultTools,
  });
  const specs = bundle.map(({ name, description, parameters }) => ({
    type: 'function',
    function: {
      name,
      description,
      parameters,
    }
  }));
  const execute = makeExecutor(bundle, root);

  const context = collectContext(open, root, readScope);
  const history = Array.isArray(messages) ? messages.slice() : [];
  if (context.length) {
    history.unshift({ role: 'system', content: formatContext(context) });
  }

  for (let step = 0; step < MAX_ITERATIONS; step++) {
    const res = await Gral.horde.sendAction('send-agent-prompt', {
      agentId,
      instruction,
      input,
      options: {
        messages: history,
        tools: specs,
      },
    });

    const calls = res.toolCalls || [];
    if (calls.length === 0) return res.response;

    if (res.response) {
      console.log(res.response);
      history.push({
        role: 'assistant',
        content: res.response,
      });
    }

    for (const call of calls) {
      call.result = execute(call.tool_name, call.arguments);
      history.push({
        role: 'tool',
        content: call,
      });
    }

    if (calls.length) {
      console.log('called: ' + calls.map(c => c.tool_name));
    }
  }

  throw new Error(`run: exceeded ${MAX_ITERATIONS} tool-call iterations`);
}

export default run;