const UserModel = require('../models/user');
const merge = require('lodash/merge');

const transformUser = user => {
  const created_at = Date.now();

  const { id, status, canEditName, suspension, disabled } = user;

  let update = {
    $unset: {
      canEditName: '',
      suspension: '',
      disabled: '',
    },
    $set: {
      status: {
        // The username status is specific to each case.
        username: {
          history: [],
        },

        // The user is not banned by default.
        banned: {
          status: false,
          history: [],
        },

        // The user is not suspended by default.
        suspension: {
          until: null,
          history: [],
        },
      },
      updated_at: created_at,
    },
  };

  if (disabled) {
    update = merge(update, {
      $set: {
        status: {
          banned: {
            status: true,
            history: [
              {
                status: true,
                created_at,
              },
            ],
          },
        },
      },
    });
  }

  // If the user has an "until" property of their suspension, then we need
  // to reflect that in the new status object.
  if (suspension && suspension.until !== null) {
    update = merge(update, {
      $set: {
        status: {
          suspension: {
            until: suspension.until,
            history: [
              {
                until: suspension.until,
                created_at,
              },
            ],
          },
        },
      },
    });
  }

  switch (status) {
    case 'ACTIVE':
      if (canEditName) {
        update = merge(update, {
          $set: {
            status: {
              username: {
                status: 'UNSET',
                history: [
                  {
                    status: 'UNSET',
                    created_at,
                  },
                ],
              },
            },
          },
        });
      } else {
        update = merge(update, {
          $set: {
            status: {
              username: {
                status: 'SET',
                history: [
                  {
                    status: 'SET',
                    created_at,
                  },
                ],
              },
            },
          },
        });
      }
      break;
    case 'BANNED':
      if (canEditName) {
        update = merge(update, {
          $set: {
            status: {
              username: {
                status: 'REJECTED',
                history: [
                  {
                    status: 'REJECTED',
                    created_at,
                  },
                ],
              },
            },
          },
        });
      } else {
        update = merge(update, {
          $set: {
            status: {
              banned: {
                status: true,
                history: [
                  {
                    status: true,
                    created_at,
                  },
                ],
              },
              username: {
                status: 'SET',
                history: [
                  {
                    status: 'SET',
                    created_at,
                  },
                ],
              },
            },
          },
        });
      }
      break;
    case 'PENDING':
      update = merge(update, {
        $set: {
          status: {
            username: {
              status: 'CHANGED',
              history: [
                {
                  status: 'CHANGED',
                  created_at,
                },
              ],
            },
          },
        },
      });
      break;
    case 'APPROVED':
      update = merge(update, {
        $set: {
          status: {
            username: {
              status: 'APPROVED',
              history: [
                {
                  status: 'APPROVED',
                  created_at,
                },
              ],
            },
          },
        },
      });
      break;
    default:
      throw new Error(`${status} is an invalid status`);
  }

  return { query: { id }, update };
};

module.exports = {
  async up({ transformSingleWithCursor }) {
    // Get the first batch of users.
    const cursor = UserModel.collection.find({
      status: {
        $in: ['ACTIVE', 'BANNED', 'PENDING', 'APPROVED'],
      },
    });

    await transformSingleWithCursor(cursor, transformUser, UserModel);
  },
};