import Vue from 'vue';
import Vuex from 'vuex';

Vue.use(Vuex);

const files = require.context('@/store', true, /^\.\/(?!-)[^.]+\.(js|mjs)$/);
const filenames = files.keys();

// Store
let storeData = {};

// Check if {dir.store}/index.js exists
const indexFilename = filenames.find(filename => filename.includes('./index.'));

if (indexFilename) {
  storeData = getModule(indexFilename);
}

// If store is not an exported method = modules store
if (typeof storeData !== 'function') {
  // Store modules
  if (!storeData.modules) {
    storeData.modules = {};
  }

  for (const filename of filenames) {
    let name = filename.replace(/^\.\//, '').replace(/\.(js|mjs)$/, '');
    if (name === 'index') continue;

    const namePath = name.split(/\//);

    name = namePath[namePath.length - 1];
    if (['state', 'getters', 'actions', 'mutations'].includes(name)) {
      const module = getModuleNamespace(storeData, namePath, true);
      appendModule(module, filename, name);
      continue;
    }

    // If file is foo/index.js, it should be saved as foo
    const isIndex = name === 'index';
    if (isIndex) {
      namePath.pop();
    }

    const module = getModuleNamespace(storeData, namePath);
    const fileModule = getModule(filename);

    name = namePath.pop();
    module[name] = module[name] || {};

    // if file is foo.js, existing properties take priority
    // because it's the least specific case
    if (!isIndex) {
      module[name] = Object.assign({}, fileModule, module[name]);
      module[name].namespaced = true;
      continue;
    }

    // if file is foo/index.js we want to overwrite properties from foo.js
    // but not from appended mods like foo/actions.js
    const appendedMods = {};
    if (module[name].appends) {
      appendedMods.appends = module[name].appends;
      for (const append of module[name].appends) {
        appendedMods[append] = module[name][append];
      }
    }

    module[name] = Object.assign({}, module[name], fileModule, appendedMods);
    module[name].namespaced = true;
  }
}

// createStore
export const createStore =
  storeData instanceof Function
    ? storeData
    : () => {
        return new Vuex.Store(
          Object.assign(
            {
              strict: process.env.NODE_ENV !== 'production',
            },
            storeData,
            {
              state: storeData.state instanceof Function ? storeData.state() : {},
            }
          )
        );
      };

// Dynamically require module
function getModule(filename) {
  const file = files(filename);
  const module = file.default || file;
  if (module.commit) {
    throw new Error('[nuxt] store/' + filename.replace('./', '') + ' should export a method which returns a Vuex instance.');
  }
  if (module.state && typeof module.state !== 'function') {
    throw new Error('[nuxt] state should be a function in store/' + filename.replace('./', ''));
  }
  return module;
}

function getModuleNamespace(storeData, namePath, forAppend = false) {
  if (namePath.length === 1) {
    if (forAppend) {
      return storeData;
    }
    return storeData.modules;
  }
  const namespace = namePath.shift();
  storeData.modules[namespace] = storeData.modules[namespace] || {};
  storeData.modules[namespace].namespaced = true;
  storeData.modules[namespace].modules = storeData.modules[namespace].modules || {};
  return getModuleNamespace(storeData.modules[namespace], namePath, forAppend);
}

function appendModule(module, filename, name) {
  const file = files(filename);
  module.appends = module.appends || [];
  module.appends.push(name);
  module[name] = file.default || file;
}