import {Component, Fragment} from 'react';
import find from 'lodash/find';
import flatMap from 'lodash/flatMap';

import SelectField from 'sentry/components/forms/fields/selectField';
import FormContext from 'sentry/components/forms/formContext';
import {SENTRY_APP_PERMISSIONS} from 'sentry/constants';
import {t} from 'sentry/locale';
import {PermissionResource, Permissions, PermissionValue} from 'sentry/types/index';

/**
 * Custom form element that presents API scopes in a resource-centric way. Meaning
 * a dropdown for each resource, that rolls up into a flat list of scopes.
 *
 *
 * API Scope vs Permission
 *
 *    "API Scopes" are the string identifier that gates an endpoint. For example,
 *    `project:read` or `org:admin`. They're made up of two parts:
 *
 *       <resource>:<access>
 *
 *    "Permissions" are a more user-friendly way of conveying this same information.
 *    They're roughly the same with one exception:
 *
 *       - No Access
 *       - Read
 *       - Read & Write
 *       - Admin
 *
 *    "Read & Write" actually maps to the `write` access level since `read` is
 *    implied. Similarly, `admin` implies `read` and `write`.
 *
 *    This components displays things per Resource. Meaning the User selects
 *    "Read", "Read & Write", or "Admin" for Project or Organization or etc.
 *
 *    === Scopes to Permissions
 *
 *    The first thing this component does on instantiation is take the list of API
 *    Scopes passed via `props` and converts them to "Permissions.
 *
 *    So a list of scopes like the following:
 *
 *       ['project:read', 'project:write', 'org:admin']
 *
 *    will become an object that looks like:
 *
 *       {
 *         'Project': 'write',
 *         'Organization': 'admin',
 *       }
 *
 *
 * State
 *
 *    This component stores state like the example object from above. When the
 *    User changes the Permission for a particular resource, it updates the
 *    `state.permissions` object to reflect the change.
 *
 *
 * Updating the Form Field Value
 *
 *    In addition to updating the state, when a value is changed this component
 *    recalculates the full list of API Scopes that need to be passed to the API.
 *
 *    So if the User has changed Project to "Admin" and Organization to "Read & Write",
 *    we end up with a `state.permissions` like:
 *
 *       {
 *         'Project': 'admin',
 *         'Organization': 'write',
 *       }
 *
 *    From there, we calculate the full list of API Scopes. This list includes all
 *    implied scopes, meaning the above state would result in:
 *
 *       ['project:read', 'project:write', 'project:admin', 'org:read', 'org:write']
 *
 */

type Props = {
  appPublished: boolean;
  onChange: (permissions: Permissions) => void;
  permissions: Permissions;
};

type State = {
  permissions: Permissions;
};

function findResource(r: PermissionResource) {
  return find(SENTRY_APP_PERMISSIONS, ['resource', r]);
}

/**
 * Converts the "Permission" values held in `state` to a list of raw
 * API scopes we can send to the server. For example:
 *
 *    ['org:read', 'org:write', ...]
 *
 */
function permissionStateToList(permissions: Permissions) {
  return flatMap(
    Object.entries(permissions),
    ([r, p]) => findResource(r as PermissionResource)?.choices?.[p]?.scopes
  );
}

export default class PermissionSelection extends Component<Props, State> {
  state: State = {
    permissions: this.props.permissions,
  };

  static contextType = FormContext;

  onChange = (resource: PermissionResource, choice: PermissionValue) => {
    const {permissions} = this.state;
    permissions[resource] = choice;
    this.save(permissions);
  };

  save = (permissions: Permissions) => {
    this.setState({permissions});
    this.props.onChange(permissions);
    this.context.form.setValue('scopes', permissionStateToList(this.state.permissions));
  };

  render() {
    const {permissions} = this.state;

    return (
      <Fragment>
        {SENTRY_APP_PERMISSIONS.map(config => {
          const options = Object.entries(config.choices).map(([value, {label}]) => ({
            value,
            label,
          }));

          const value = permissions[config.resource];

          return (
            <SelectField
              // These are not real fields we want submitted, so we use
              // `--permission` as a suffix here, then filter these
              // fields out when submitting the form in
              // sentryApplicationDetails.jsx
              name={`${config.resource}--permission`}
              key={config.resource}
              options={options}
              help={config.help}
              label={config.label || config.resource}
              onChange={this.onChange.bind(this, config.resource)}
              value={value}
              defaultValue={value}
              disabled={this.props.appPublished}
              disabledReason={t('Cannot update permissions on a published integration')}
            />
          );
        })}
      </Fragment>
    );
  }
}