import type { Command } from 'commander';
import { spawnSync } from 'node:child_process';
import { accessSync, constants } from 'node:fs';
import { homedir } from 'node:os';
import { join } from 'node:path';

import { DEFAULT_MOSAIC_HOME } from '../constants.js';
import { execBrainTool } from './brain-dispatch.js';

/**
 * `mosaic comms send` — routed agent messaging (FLEET-COMMS.md doctrine).
 *
 * Same-host (default): brain tools/tmux/agent-send.sh. Inter-site
 * (--site <site>): the fleet-comms repo's comms-send.sh — never for
 * local traffic (a git round trip per message; Jason 2026-08-28).
 *
 * Exit codes pass through BOTH paths. rc=2 (text in pane, still draft) is
 * a CONTRACT, not a failure: never retry, confirm with capture-pane.
 */
export interface CommsSendOptions {
  readonly class?: string;
  readonly file?: string;
  readonly socket?: string;
  readonly site?: string;
  readonly commsRepo?: string;
}

export function defaultCommsRepo(): string {
  return process.env['MOSAIC_FLEET_COMMS_REPO'] ?? join(homedir(), 'src', 'fleet-comms');
}

/** Build the agent-send.sh argv for the same-host path. */
export function tmuxSendArgs(target: string, message: string, opts: CommsSendOptions): string[] {
  const args = ['-s', target];
  if (opts.class) args.push('-C', opts.class);
  if (opts.socket) args.push('-L', opts.socket);
  if (opts.file) args.push('-f', opts.file);
  else args.push('-m', message);
  return args;
}

/** Build the comms-send.sh argv for the inter-site path. */
export function fleetCommsSendArgs(
  site: string,
  target: string,
  message: string,
  opts: CommsSendOptions,
): string[] {
  const args = ['-t', `${site}/${target}`];
  if (opts.class) args.push('-c', opts.class);
  args.push('-m', message);
  return args;
}

export function registerCommsCommand(program: Command): void {
  const cmd: Command = program
    .command('comms')
    .description(
      'Routed agent messaging: tmux same-host (default), fleet-comms inter-site (--site)',
    )
    .command('send')
    .description('send <target> [message...] — same-host tmux unless --site is given')
    .option('--class <class>', 'terminal-log | actionable | human | reaction | digest')
    .option('--file <path>', 'message body from file (same-host path only)')
    .option('--socket <name>', 'tmux socket for the same-host send (e.g. mosaic-fleet)')
    .option('--site <site>', 'route via fleet-comms to <site>/<target>')
    .option('--comms-repo <path>', 'fleet-comms checkout', defaultCommsRepo())
    .argument('<target>', 'destination seat (session name)')
    .argument('[message...]', 'message text (joined; or use --file)')
    .action(
      async (
        target: string,
        messageWords: string[],
        opts: CommsSendOptions & Record<string, unknown>,
        command: Command,
      ) => {
        let mosaicHome: string | undefined;
        for (let anc: Command | null = command; anc; anc = anc.parent) {
          const v = (anc.opts() as Record<string, string | undefined>)['mosaicHome'];
          if (v !== undefined) {
            mosaicHome = v;
            break;
          }
        }
        const home = mosaicHome ?? DEFAULT_MOSAIC_HOME;
        const message = messageWords.join(' ');

        if (opts.site) {
          const repo = opts.commsRepo ?? defaultCommsRepo();
          const tool = join(repo, 'tools', 'comms-send.sh');
          try {
            accessSync(tool, constants.X_OK);
          } catch {
            console.error(
              `mosaic comms: fleet-comms sender not found (expected ${tool}). ` +
                'Clone the fleet-comms repo or point --comms-repo at it.',
            );
            process.exitCode = 127;
            return;
          }
          if (!process.env['MOSAIC_AGENT_NAME']) {
            console.error(
              'mosaic comms: inter-site sends require MOSAIC_AGENT_NAME (sending identity).',
            );
            process.exitCode = 2; // invocation defect: fixable by the caller
            return;
          }
          // comms-send.sh locates its working repo via FLEET_COMMS_REPO
          // (default $HOME/src/fleet-comms); without this, --comms-repo
          // would select the executable but not the repository it operates
          // on (codex review of 9c8b6ebf).
          const env = { ...process.env, FLEET_COMMS_SITE: opts.site, FLEET_COMMS_REPO: repo };
          const result = spawnSync(tool, fleetCommsSendArgs(opts.site, target, message, opts), {
            stdio: 'inherit',
            env,
          });
          process.exitCode = result.status ?? 125;
          return;
        }

        // Same-host: the brain tool owns validation (bad class -> its rc 3)
        // and absence (execBrainTool -> 127 with the resolved path).
        process.exitCode = execBrainTool(
          home,
          'tools/tmux/agent-send.sh',
          tmuxSendArgs(target, message, opts),
        );
      },
    );

  cmd.addHelpText(
    'after',
    '\nExit codes pass through. rc=2 means the text reached the pane but is still a draft: NEVER retry (double-send); confirm with tmux capture-pane.',
  );
}