/**
 * `mosaic fleet backlog <sub> --json` — Mosaic-native backlog of record.
 *
 * Mosaic OWNS this backlog end-to-end on its existing Postgres storage layer
 * (`@mosaicstack/db`). It REPLACES the former Hermes adapter — there is NO
 * runtime dependency on Hermes.
 *
 * Storage tier (the existing storage-layer convention, no new engine):
 *   - default: embedded PGlite at <mosaicHome>/fleet/backlog (real Postgres
 *     semantics, persisted on disk so the operator's backlog survives reboots
 *     and `mosaic update` — see install.sh PRESERVE_PATHS).
 *   - DATABASE_URL set: full server Postgres — same code, no change.
 *
 * Migrations run on first use so the `backlog` table always exists.
 */

import { mkdir } from 'node:fs/promises';
import { homedir } from 'node:os';
import { join } from 'node:path';
import type { Command } from 'commander';
import {
  BacklogService,
  DEFAULT_CLAIM_TTL_SECONDS,
  type BacklogCard,
  type DbHandle,
} from '@mosaicstack/db';

function defaultMosaicHome(): string {
  return process.env['MOSAIC_HOME'] ?? join(homedir(), '.config', 'mosaic');
}

/** Resolve where the embedded PGlite backlog store lives (default tier). */
export function defaultBacklogDataDir(mosaicHome = defaultMosaicHome()): string {
  return join(mosaicHome, 'fleet', 'backlog');
}

/**
 * Open a db handle for the backlog and ensure the schema exists.
 *
 * Tier detection mirrors the storage layer: DATABASE_URL => server Postgres
 * (migrations applied via runMigrations); otherwise embedded PGlite at the
 * fleet/backlog data dir (migrations applied via runPgliteMigrations).
 */
async function openBacklogDb(mosaicHome: string): Promise<DbHandle> {
  const { createDb, createPgliteDb, runMigrations, runPgliteMigrations } =
    await import('@mosaicstack/db');
  const url = process.env['DATABASE_URL'];
  if (url) {
    await runMigrations(url);
    return createDb(url);
  }
  const dataDir = process.env['PGLITE_DATA_DIR'] ?? defaultBacklogDataDir(mosaicHome);
  // PGlite writes a file-backed store to dataDir but does not create missing
  // parent directories (e.g. <mosaicHome>/fleet). Create them first. Skip for
  // the in-memory pseudo-paths so a memory:// store never touches the fs.
  if (!dataDir.startsWith('memory://') && dataDir !== ':memory:') {
    await mkdir(dataDir, { recursive: true });
  }
  const handle = createPgliteDb(dataDir);
  await runPgliteMigrations(handle);
  return handle;
}

function parseDependsOn(value?: string): string[] {
  if (!value) return [];
  return value
    .split(',')
    .map((s) => s.trim())
    .filter((s) => s.length > 0);
}

function parseAcceptance(value?: string): unknown {
  if (!value) return null;
  try {
    return JSON.parse(value);
  } catch {
    // Fall back to a list of newline/semicolon-separated criteria.
    return value
      .split(/[\n;]/)
      .map((s) => s.trim())
      .filter((s) => s.length > 0);
  }
}

function printCard(card: BacklogCard | null, json?: boolean): void {
  if (json) {
    console.log(JSON.stringify(card));
    return;
  }
  if (!card) {
    console.log('(none)');
    return;
  }
  const deps = card.dependsOn.length ? card.dependsOn.join(',') : '-';
  console.log(
    `${card.id}\t[${card.status}]\tp=${card.priority}\tphase=${card.phase ?? '-'}\tdeps=${deps}\t${card.title}`,
  );
}

function printCards(cards: BacklogCard[], json?: boolean): void {
  if (json) {
    console.log(JSON.stringify(cards));
    return;
  }
  if (cards.length === 0) {
    console.log('(no cards)');
    return;
  }
  for (const card of cards) printCard(card, false);
}

/**
 * Register `backlog` under an existing `fleet` command.
 * `mosaicHomeFor` resolves the active --mosaic-home (parent flag) at call time.
 */
export function registerFleetBacklogCommand(
  fleetCmd: Command,
  mosaicHomeFor: () => string,
): Command {
  const backlogCmd = fleetCmd
    .command('backlog')
    .description('Mosaic-native backlog of record (atomic claim + TTL, deps DAG)');

  const withSvc = async <T>(fn: (svc: BacklogService) => Promise<T>): Promise<T> => {
    const handle = await openBacklogDb(mosaicHomeFor());
    try {
      return await fn(new BacklogService(handle.db));
    } finally {
      await handle.close();
    }
  };

  backlogCmd
    .command('create')
    .description('Create a backlog card (idempotency_key dedups)')
    .requiredOption('--id <id>', 'Stable card id')
    .requiredOption('--title <title>', 'Card title')
    .option('--body <body>', 'Card body / description')
    .option('--phase <phase>', 'Board/phase grouping')
    .option('--priority <n>', 'Priority (higher = sooner)', (v) => parseInt(v, 10), 0)
    .option('--depends-on <ids>', 'Comma-separated dependency card ids')
    .option('--acceptance <json>', 'Acceptance criteria (JSON or ;/newline list)')
    .option('--idempotency-key <key>', 'Dedup key; repeat returns the existing card')
    .option('--json', 'Print JSON')
    .action(
      async (opts: {
        id: string;
        title: string;
        body?: string;
        phase?: string;
        priority: number;
        dependsOn?: string;
        acceptance?: string;
        idempotencyKey?: string;
        json?: boolean;
      }) => {
        const card = await withSvc((svc) =>
          svc.create({
            id: opts.id,
            title: opts.title,
            body: opts.body ?? null,
            phase: opts.phase ?? null,
            priority: opts.priority,
            dependsOn: parseDependsOn(opts.dependsOn),
            acceptance: parseAcceptance(opts.acceptance),
            idempotencyKey: opts.idempotencyKey ?? null,
          }),
        );
        printCard(card, opts.json);
      },
    );

  backlogCmd
    .command('list')
    .description('List cards (filters: --status, --phase, --ready-only)')
    .option('--status <status>', 'Filter by status: ready|claimed|blocked|done')
    .option('--phase <phase>', 'Filter by phase')
    .option('--ready-only', 'Only cards that are ready AND have all deps done')
    .option('--json', 'Print JSON')
    .action(
      async (opts: {
        status?: BacklogCard['status'];
        phase?: string;
        readyOnly?: boolean;
        json?: boolean;
      }) => {
        const cards = await withSvc((svc) =>
          svc.list({
            ...(opts.status ? { status: opts.status } : {}),
            ...(opts.phase ? { phase: opts.phase } : {}),
            ...(opts.readyOnly ? { readyOnly: true } : {}),
          }),
        );
        printCards(cards, opts.json);
      },
    );

  backlogCmd
    .command('claim')
    .description('Atomically claim the highest-priority ready card (FOR UPDATE SKIP LOCKED)')
    .requiredOption('--owner <owner>', 'Claim owner (worker/agent id)')
    .option(
      '--ttl <sec>',
      'Claim TTL in seconds',
      (v) => parseInt(v, 10),
      DEFAULT_CLAIM_TTL_SECONDS,
    )
    .option('--id <id>', 'Claim a specific card by id')
    .option('--json', 'Print JSON')
    .action(async (opts: { owner: string; ttl: number; id?: string; json?: boolean }) => {
      const card = await withSvc((svc) =>
        svc.claim({ owner: opts.owner, ttlSeconds: opts.ttl, ...(opts.id ? { id: opts.id } : {}) }),
      );
      printCard(card, opts.json);
      if (!card && !opts.json) process.exitCode = 0;
    });

  backlogCmd
    .command('reclaim')
    .description('Release expired claims back to ready (or a specific --id)')
    .option('--id <id>', 'Release a specific card regardless of expiry')
    .option('--json', 'Print JSON')
    .action(async (opts: { id?: string; json?: boolean }) => {
      const result = await withSvc((svc) => svc.reclaim(opts.id ? { id: opts.id } : {}));
      if (opts.json) {
        console.log(JSON.stringify(result));
      } else if (result.reclaimed.length === 0) {
        console.log('(nothing to reclaim)');
      } else {
        console.log(`reclaimed: ${result.reclaimed.join(', ')}`);
      }
    });

  backlogCmd
    .command('link')
    .description('Add a depends_on edge (--from depends on --to)')
    .requiredOption('--from <id>', 'Card that gains the dependency')
    .requiredOption('--to <id>', 'Card it now depends on')
    .option('--json', 'Print JSON')
    .action(async (opts: { from: string; to: string; json?: boolean }) => {
      const card = await withSvc((svc) => svc.link(opts.from, opts.to));
      printCard(card, opts.json);
    });

  backlogCmd
    .command('stats')
    .description('Counts by status, oldest-ready age, expired-claim count')
    .option('--json', 'Print JSON')
    .action(async (opts: { json?: boolean }) => {
      const stats = await withSvc((svc) => svc.stats());
      if (opts.json) {
        console.log(JSON.stringify(stats));
        return;
      }
      console.log(`total: ${stats.total}`);
      console.log(
        `ready=${stats.counts.ready} claimed=${stats.counts.claimed} ` +
          `blocked=${stats.counts.blocked} done=${stats.counts.done}`,
      );
      console.log(`oldest-ready-age: ${stats.oldestReadyAgeSeconds ?? '-'}s`);
      console.log(`expired-claims: ${stats.expiredClaimCount}`);
    });

  backlogCmd
    .command('block')
    .description('Mark a card blocked')
    .requiredOption('--id <id>', 'Card id')
    .option('--json', 'Print JSON')
    .action(async (opts: { id: string; json?: boolean }) => {
      const card = await withSvc((svc) => svc.block(opts.id));
      printCard(card, opts.json);
    });

  backlogCmd
    .command('complete')
    .description('Mark a card done')
    .requiredOption('--id <id>', 'Card id')
    .option('--json', 'Print JSON')
    .action(async (opts: { id: string; json?: boolean }) => {
      const card = await withSvc((svc) => svc.complete(opts.id));
      printCard(card, opts.json);
    });

  return backlogCmd;
}