import type { Command } from 'commander';
import { resolve } from 'path';
import { homedir } from 'os';
import type { Skill } from '../skills/index.js';
import { loadAllSkills } from '../skills/index.js';
import { loadConfigSafe } from './shared.js';

export interface SkillListRow {
  name: string;
  tier: Skill['manifest']['tier'];
  status: 'available' | 'unavailable';
  reason?: string;
}

export function toSkillListRows(skills: Skill[]): SkillListRow[] {
  return skills
    .map((skill) => ({
      name: skill.manifest.name,
      tier: skill.manifest.tier,
      status: (skill.available ? 'available' : 'unavailable') as SkillListRow['status'],
      reason: skill.unavailableReasons?.join('; '),
    }))
    .sort((a, b) => a.name.localeCompare(b.name));
}

export function renderSkillsTable(rows: SkillListRow[]): string {
  if (rows.length === 0) {
    return 'No skills found.';
  }

  const nameWidth = Math.max('NAME'.length, ...rows.map((row) => row.name.length));
  const tierWidth = Math.max('TIER'.length, ...rows.map((row) => row.tier.length));
  const statusWidth = Math.max('STATUS'.length, ...rows.map((row) => row.status.length));

  const lines = [
    `${'NAME'.padEnd(nameWidth)}  ${'TIER'.padEnd(tierWidth)}  ${'STATUS'.padEnd(statusWidth)}  REASON`,
    `${'-'.repeat(nameWidth)}  ${'-'.repeat(tierWidth)}  ${'-'.repeat(statusWidth)}  ------`,
  ];

  for (const row of rows) {
    lines.push(
      `${row.name.padEnd(nameWidth)}  ${row.tier.padEnd(tierWidth)}  ${row.status.padEnd(statusWidth)}  ${row.reason ?? ''}`,
    );
  }

  return lines.join('\n');
}

export function renderSkillInfo(skill: Skill): string {
  const lines: string[] = [
    `Name: ${skill.manifest.name}`,
    `Description: ${skill.manifest.description}`,
    `Version: ${skill.manifest.version}`,
    `Tier: ${skill.manifest.tier}`,
    `Status: ${skill.available ? 'available' : 'unavailable'}`,
    `Directory: ${skill.directory}`,
  ];

  if (skill.manifest.author) {
    lines.push(`Author: ${skill.manifest.author}`);
  }

  if (skill.manifest.tools && skill.manifest.tools.length > 0) {
    lines.push(`Tools: ${skill.manifest.tools.join(', ')}`);
  }

  if (skill.unavailableReasons && skill.unavailableReasons.length > 0) {
    lines.push(`Unavailable reasons: ${skill.unavailableReasons.join('; ')}`);
  }

  return lines.join('\n');
}

function loadSkillsFromConfig(configPath?: string): { skills?: Skill[]; error?: string } {
  const loaded = loadConfigSafe(configPath);
  if (loaded.error || !loaded.config) {
    return { error: loaded.error ?? 'Failed to load config' };
  }

  const defaultManagedDir = resolve(homedir(), '.flynn/workspace/skills');
  const skills = loadAllSkills({
    bundledDir: loaded.config.skills.bundled_dir,
    managedDir: loaded.config.skills.managed_dir ?? defaultManagedDir,
    workspaceDir: loaded.config.skills.workspace_dir,
  });

  return { skills };
}

export function registerSkillsCommand(program: Command): void {
  const skills = program
    .command('skills')
    .description('Manage Flynn skills')
    .action(() => {
      skills.outputHelp();
    });

  skills
    .command('list')
    .description('List discovered skills')
    .option('--json', 'Output as JSON')
    .option('-c, --config <path>', 'Config file path')
    .action((opts: { json?: boolean; config?: string }) => {
      const loaded = loadSkillsFromConfig(opts.config);
      if (loaded.error || !loaded.skills) {
        console.error(loaded.error ?? 'Failed to load skills');
        process.exitCode = 1;
        return;
      }

      const rows = toSkillListRows(loaded.skills);
      if (opts.json) {
        console.log(JSON.stringify(rows, null, 2));
        return;
      }

      console.log(renderSkillsTable(rows));
    });

  skills
    .command('info <name>')
    .description('Show details for a skill')
    .option('--json', 'Output as JSON')
    .option('-c, --config <path>', 'Config file path')
    .action((name: string, opts: { json?: boolean; config?: string }) => {
      const loaded = loadSkillsFromConfig(opts.config);
      if (loaded.error || !loaded.skills) {
        console.error(loaded.error ?? 'Failed to load skills');
        process.exitCode = 1;
        return;
      }

      const skill = loaded.skills.find((item) => item.manifest.name === name);
      if (!skill) {
        console.error(`Skill '${name}' not found.`);
        process.exitCode = 1;
        return;
      }

      if (opts.json) {
        console.log(JSON.stringify(skill, null, 2));
        return;
      }

      console.log(renderSkillInfo(skill));
    });
}