import { spawnSync } from 'node:child_process';
import type { Command } from 'commander';
import { createConfigService } from '../config/config-service.js';
import { DEFAULT_MOSAIC_HOME } from '../constants.js';

/**
 * Resolve mosaicHome from the MOSAIC_HOME env var or the default constant.
 */
function getMosaicHome(): string {
  return process.env['MOSAIC_HOME'] ?? DEFAULT_MOSAIC_HOME;
}

/**
 * Guard: print an error and exit(1) if config has not been initialised.
 */
function assertInitialized(svc: ReturnType<typeof createConfigService>): void {
  if (!svc.isInitialized()) {
    console.error('No config found — run `mosaic wizard` first.');
    process.exit(1);
  }
}

/**
 * Flatten a nested object into dotted-key rows for table display.
 */
function flattenConfig(obj: Record<string, unknown>, prefix = ''): Array<[string, string]> {
  const rows: Array<[string, string]> = [];
  for (const [k, v] of Object.entries(obj)) {
    const key = prefix ? `${prefix}.${k}` : k;
    if (v !== null && typeof v === 'object' && !Array.isArray(v)) {
      rows.push(...flattenConfig(v as Record<string, unknown>, key));
    } else {
      rows.push([key, v === undefined || v === null ? '' : String(v)]);
    }
  }
  return rows;
}

/**
 * Print rows as a padded ASCII table.
 */
function printTable(rows: Array<[string, string]>): void {
  if (rows.length === 0) {
    console.log('(no config values)');
    return;
  }
  const maxKey = Math.max(...rows.map(([k]) => k.length));
  const header = `${'Key'.padEnd(maxKey)}  Value`;
  const divider = '-'.repeat(header.length);
  console.log(header);
  console.log(divider);
  for (const [k, v] of rows) {
    console.log(`${k.padEnd(maxKey)}  ${v}`);
  }
}

export function registerConfigCommand(program: Command): void {
  const cmd = program
    .command('config')
    .description('Manage Mosaic framework configuration')
    .configureHelp({ sortSubcommands: true });

  // ── config show ─────────────────────────────────────────────────────────

  cmd
    .command('show')
    .description('Print the current resolved config')
    .option('-f, --format <format>', 'Output format: table or json', 'table')
    .action(async (opts: { format: string }) => {
      const mosaicHome = getMosaicHome();
      const svc = createConfigService(mosaicHome, mosaicHome);
      assertInitialized(svc);

      const config = await svc.readAll();

      if (opts.format === 'json') {
        console.log(JSON.stringify(config, null, 2));
        return;
      }

      // Default: table
      const rows = flattenConfig(config as unknown as Record<string, unknown>);
      printTable(rows);
    });

  // ── config get <key> ────────────────────────────────────────────────────

  cmd
    .command('get <key>')
    .description('Print a single config value (supports dotted keys, e.g. soul.agentName)')
    .action(async (key: string) => {
      const mosaicHome = getMosaicHome();
      const svc = createConfigService(mosaicHome, mosaicHome);
      assertInitialized(svc);

      const value = await svc.getValue(key);
      if (value === undefined) {
        console.error(`Key "${key}" not found.`);
        process.exit(1);
      }
      if (typeof value === 'object') {
        console.log(JSON.stringify(value, null, 2));
      } else {
        console.log(String(value));
      }
    });

  // ── config set <key> <value> ────────────────────────────────────────────

  cmd
    .command('set <key> <value>')
    .description(
      'Set a config value and persist (supports dotted keys, e.g. soul.agentName "Jarvis")',
    )
    .action(async (key: string, value: string) => {
      const mosaicHome = getMosaicHome();
      const svc = createConfigService(mosaicHome, mosaicHome);
      assertInitialized(svc);

      let previous: unknown;
      try {
        previous = await svc.setValue(key, value);
      } catch (err) {
        console.error(err instanceof Error ? err.message : String(err));
        process.exit(1);
      }

      const prevStr = previous === undefined ? '(unset)' : String(previous);
      console.log(`${key}`);
      console.log(`  old: ${prevStr}`);
      console.log(`  new: ${value}`);
    });

  // ── config edit ─────────────────────────────────────────────────────────

  cmd
    .command('edit')
    .description('Open the config directory in $EDITOR (or vi)')
    .option('-s, --section <section>', 'Open a specific section file: soul | user | tools')
    .action(async (opts: { section?: string }) => {
      const mosaicHome = getMosaicHome();
      const svc = createConfigService(mosaicHome, mosaicHome);
      assertInitialized(svc);

      const editor = process.env['EDITOR'] ?? 'vi';

      let targetPath: string;
      if (opts.section) {
        const validSections = ['soul', 'user', 'tools'] as const;
        if (!validSections.includes(opts.section as (typeof validSections)[number])) {
          console.error(`Invalid section "${opts.section}". Choose: soul, user, tools`);
          process.exit(1);
        }
        targetPath = svc.getConfigPath(opts.section as 'soul' | 'user' | 'tools');
      } else {
        targetPath = svc.getConfigPath();
      }

      const result = spawnSync(editor, [targetPath], { stdio: 'inherit' });

      if (result.error) {
        console.error(`Failed to open editor: ${result.error.message}`);
        process.exit(1);
      }

      if (result.status !== 0) {
        console.error(`Editor exited with code ${String(result.status ?? 1)}`);
        process.exit(result.status ?? 1);
      }

      // Re-read after edit and report any issues
      try {
        await svc.readAll();
        console.log('Config looks valid.');
      } catch (err) {
        console.error('Warning: config may have validation issues:');
        console.error(err instanceof Error ? err.message : String(err));
        process.exit(1);
      }
    });

  // ── config path ─────────────────────────────────────────────────────────

  cmd
    .command('path')
    .description('Print the active config directory path (for scripting)')
    .option(
      '-s, --section <section>',
      'Print path for a specific section file: soul | user | tools',
    )
    .action(async (opts: { section?: string }) => {
      const mosaicHome = getMosaicHome();
      const svc = createConfigService(mosaicHome, mosaicHome);

      if (opts.section) {
        const validSections = ['soul', 'user', 'tools'] as const;
        if (!validSections.includes(opts.section as (typeof validSections)[number])) {
          console.error(`Invalid section "${opts.section}". Choose: soul, user, tools`);
          process.exit(1);
        }
        console.log(svc.getConfigPath(opts.section as 'soul' | 'user' | 'tools'));
      } else {
        console.log(svc.getConfigPath());
      }
    });
}