const path = require('path');
const { getResourceDir, resourceTypeToDirName } = require('./paths');
const { ensureDir, listJsonFiles, readJsonIfExists, writeJson } = require('./fs');

function resourcePath(resourceType, resourceId) {
  return path.join(getResourceDir(resourceType), `${resourceId}.json`);
}

function nowIso() {
  return new Date().toISOString();
}

function createResourceDocument({
  id,
  resource_type,
  desired_state,
  current_state,
  last_applied_state,
  metadata,
  created_at,
  updated_at,
}) {
  const timestamp = nowIso();

  return {
    id,
    resource_type,
    schema_version: 'v1',
    desired_state: desired_state || {},
    current_state: current_state || {},
    last_applied_state: last_applied_state || {},
    metadata: metadata || {},
    created_at: created_at || timestamp,
    updated_at: updated_at || timestamp,
  };
}

async function getResource(resourceType, resourceId) {
  return readJsonIfExists(resourcePath(resourceType, resourceId));
}

async function saveResource(document) {
  const existing = await getResource(document.resource_type, document.id);
  const next = createResourceDocument({
    ...document,
    created_at: existing ? existing.created_at : document.created_at,
    updated_at: nowIso(),
  });

  await writeJson(resourcePath(next.resource_type, next.id), next);
  return next;
}

async function patchResourceState(resourceType, resourceId, patch) {
  const existing = await getResource(resourceType, resourceId);

  if (!existing) {
    return null;
  }

  return saveResource({
    ...existing,
    desired_state: patch.desired_state || existing.desired_state,
    current_state: patch.current_state || existing.current_state,
    last_applied_state: patch.last_applied_state || existing.last_applied_state,
    metadata: patch.metadata || existing.metadata,
  });
}

async function listResources(resourceType) {
  const files = await listJsonFiles(getResourceDir(resourceType));
  return Promise.all(files.map((filePath) => readJsonIfExists(filePath)));
}

async function listAllResources() {
  const result = {};

  for (const resourceType of Object.keys(resourceTypeToDirName)) {
    await ensureDir(getResourceDir(resourceType));
    result[resourceType] = await listResources(resourceType);
  }

  return result;
}

module.exports = {
  createResourceDocument,
  getResource,
  saveResource,
  patchResourceState,
  listResources,
  listAllResources,
};