/**
 * Copyright 2020 Inrupt Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
 * Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

import {
  internal_fetchAcl,
  internal_getResourceAcl,
  internal_setAcl,
  internal_setResourceAcl,
} from "../acl/acl.internal";
import {
  getAgentAccess as getAgentAccessWac,
  getAgentAccessAll as getAgentAccessAllWac,
  setAgentResourceAccess as setAgentResourceAccessWac,
} from "../acl/agent";
import {
  getGroupAccess as getGroupAccessWac,
  getGroupAccessAll as getGroupAccessAllWac,
  setGroupResourceAccess as setGroupResourceAccessWac,
} from "../acl/group";
import {
  getPublicAccess as getPublicAccessWac,
  setPublicResourceAccess as setPublicResourceAccessWac,
} from "../acl/class";
import {
  IriString,
  UrlString,
  WebId,
  WithServerResourceInfo,
} from "../interfaces";
import { internal_defaultFetchOptions } from "../resource/resource";
import { Access } from "./universal";
import {
  Access as AclAccess,
  AclDataset,
  createAclFromFallbackAcl,
  getResourceAcl,
  hasAccessibleAcl,
  hasFallbackAcl,
  hasResourceAcl,
  saveAclFor,
  WithAccessibleAcl,
  WithResourceAcl,
} from "../acl/acl";

export type WacAccess = (
  | { controlRead: true; controlWrite: true }
  | { controlRead: false; controlWrite: false }
) & {
  read: boolean;
  append: boolean;
  write: boolean;
};

function universalAccessToAcl(
  newAccess: Partial<WacAccess>,
  previousAccess: AclAccess
): AclAccess {
  // Universal access is aligned on ACP, which means there is a distinction between
  // controlRead and controlWrite. This split doesn't exist in WAC, which is why
  // the type for the input variable of this function is a restriction on the
  // universal Access type.
  if (newAccess.controlRead !== newAccess.controlWrite) {
    throw new Error(
      "For Pods using Web Access Control, controlRead and controlWrite must be equal."
    );
  }
  return {
    read: newAccess.read ?? previousAccess.read,
    append: newAccess.append ?? previousAccess.append,
    write: newAccess.write ?? previousAccess.write,
    control: newAccess.controlRead ?? previousAccess.control,
  };
}

function aclAccessToUniversal(access: AclAccess): WacAccess {
  // In ACL, denying access to an actor is a notion that doesn't exist, so an
  // access is either granted or not for a given mode.
  // This creates a misalignment with the ACP notion of an access being granted,
  // denied, or simply not mentioned. Here, we convert the boolean vision of
  // ACL into the boolean or undefined vision of ACP.
  return {
    read: access.read,
    write: access.write,
    append: access.append,
    controlRead: access.control,
    controlWrite: access.control,
  } as WacAccess;
}

async function getActorAccess(
  resource: WithServerResourceInfo,
  actor: IriString,
  accessEvaluationCallback: typeof getAgentAccessWac,
  options: Partial<typeof internal_defaultFetchOptions>
): Promise<Access | null> {
  const resourceAcl = await internal_fetchAcl(resource, options);
  const wacAccess = accessEvaluationCallback(
    internal_setAcl(resource, resourceAcl),
    actor
  );
  if (wacAccess === null) {
    return null;
  }
  return aclAccessToUniversal(wacAccess);
}

async function getActorClassAccess(
  resource: WithServerResourceInfo,
  accessEvaluationCallback: typeof getPublicAccessWac,
  options: Partial<typeof internal_defaultFetchOptions>
): Promise<Access | null> {
  const resourceAcl = await internal_fetchAcl(resource, options);
  const wacAccess = accessEvaluationCallback(
    internal_setAcl(resource, resourceAcl)
  );
  if (wacAccess === null) {
    return null;
  }
  return aclAccessToUniversal(wacAccess);
}

async function getActorAccessAll(
  resource: WithServerResourceInfo,
  accessEvaluationCallback: typeof getAgentAccessAllWac,
  options: Partial<typeof internal_defaultFetchOptions>
): Promise<Record<WebId, WacAccess> | null> {
  const resourceAcl = await internal_fetchAcl(resource, options);
  const wacAgentAccess = accessEvaluationCallback(
    internal_setAcl(resource, resourceAcl)
  );
  if (wacAgentAccess === null) {
    return null;
  }
  const result: Record<WebId, WacAccess> = {};
  for (const [webId, wacAccess] of Object.entries(wacAgentAccess)) {
    result[webId] = aclAccessToUniversal(wacAccess);
  }
  return result;
}

/**
 * For a given Resource, look up its metadata, and read the Access permissions
 * granted to the given Agent.
 *
 * Note that this only lists permissions granted to the given Agent individually,
 * and will not exhaustively list modes the given Agent may have access to because
 * they apply to everyone, or because they apply to the Agent through a group for
 * instance.
 *
 * @param resource The URL of the Resource for which we want to list Access
 * @param agent The Agent for which the Access is granted
 * @param options Optional parameter `options.fetch`: An alternative `fetch` function to make the HTTP request, compatible with the browser-native [fetch API](https://developer.mozilla.org/docs/Web/API/WindowOrWorkerGlobalScope/fetch#parameters).
 * @returns What Access modes are granted to the given Agent explicitly, or null if it could not be determined.
 */
export function getAgentAccess(
  resource: WithServerResourceInfo,
  agent: WebId,
  options: Partial<
    typeof internal_defaultFetchOptions
  > = internal_defaultFetchOptions
): Promise<Access | null> {
  return getActorAccess(resource, agent, getAgentAccessWac, options);
}

/**
 * For a given Resource, look up its metadata, and read the Access permissions
 * granted to the given Group.
 *
 * Note that this only lists permissions granted to the given Group individually,
 * and will not exhaustively list modes the given Group may have access to because
 * they apply to everyone, or because they apply to the Group through another
 * Group that may contain it for instance.
 *
 * @param resource The URL of the Resource for which we want to list Access
 * @param group The Group for which the Access is granted
 * @param options Optional parameter `options.fetch`: An alternative `fetch` function to make the HTTP request, compatible with the browser-native [fetch API](https://developer.mozilla.org/docs/Web/API/WindowOrWorkerGlobalScope/fetch#parameters).
 * @returns What Access modes are granted to the given Group explicitly, or null if it could not be determined.
 */
export function getGroupAccess(
  resource: WithServerResourceInfo,
  group: UrlString,
  options: Partial<
    typeof internal_defaultFetchOptions
  > = internal_defaultFetchOptions
): Promise<Access | null> {
  return getActorAccess(resource, group, getGroupAccessWac, options);
}

/**
 * For a given Resource, look up its metadata, and read the Access permissions
 * granted to everyone.
 *
 * Note that this only lists permissions explicitly granted to everyone as a whole,
 * and will not exhaustively list modes any individual Agent or Group may have
 * access to because they specifically apply to them only.
 *
 * @param resource The URL of the Resource for which we want to list public Access
 * @param options Optional parameter `options.fetch`: An alternative `fetch` function to make the HTTP request, compatible with the browser-native [fetch API](https://developer.mozilla.org/docs/Web/API/WindowOrWorkerGlobalScope/fetch#parameters).
 * @returns What Access modes are granted to the everyone explicitly, or null if it could not be determined.
 */
export function getPublicAccess(
  resource: WithServerResourceInfo,
  options: Partial<
    typeof internal_defaultFetchOptions
  > = internal_defaultFetchOptions
): Promise<Access | null> {
  return getActorClassAccess(resource, getPublicAccessWac, options);
}

/**
 * For a given Resource, look up its metadata, and read the Access permissions
 * granted explicitly to each individual Agent.
 *
 * Note that this only lists permissions granted to each Agent individually,
 * and will not exhaustively list modes any Agent may have access to because
 * they apply to everyone, or because they apply to an Agent through a group for
 * instance.
 *
 * @param resource The URL of the Resource for which we want to list Agents Access
 * @param options Optional parameter `options.fetch`: An alternative `fetch` function to make the HTTP request, compatible with the browser-native [fetch API](https://developer.mozilla.org/docs/Web/API/WindowOrWorkerGlobalScope/fetch#parameters).
 * @returns A map of Agent WebIDs and the access granted to them, or null if it could not be determined.
 */
export function getAgentAccessAll(
  resource: WithServerResourceInfo,
  options: Partial<
    typeof internal_defaultFetchOptions
  > = internal_defaultFetchOptions
): Promise<Record<WebId, WacAccess> | null> {
  return getActorAccessAll(resource, getAgentAccessAllWac, options);
}

/**
 * For a given Resource, look up its metadata, and read the Access permissions
 * granted explicitly to each individual Group.
 *
 * Note that this only lists permissions granted to each Group individually,
 * and will not exhaustively list modes any Group may have access to because
 * they apply individually to all of the Agents in the Group, or to everyone
 * for instance.
 *
 * @param resource The URL of the Resource for which we want to list Agents Access
 * @param options Optional parameter `options.fetch`: An alternative `fetch` function to make the HTTP request, compatible with the browser-native [fetch API](https://developer.mozilla.org/docs/Web/API/WindowOrWorkerGlobalScope/fetch#parameters).
 * @returns A map of Group URLs and the access granted to them, or null if it could not be determined.
 */
export function getGroupAccessAll(
  resource: WithServerResourceInfo,
  options: Partial<
    typeof internal_defaultFetchOptions
  > = internal_defaultFetchOptions
): Promise<Record<WebId, WacAccess> | null> {
  return getActorAccessAll(resource, getGroupAccessAllWac, options);
}

async function prepareResourceAcl<T extends WithServerResourceInfo>(
  resource: T,
  options: Partial<typeof internal_defaultFetchOptions>
): Promise<(T & WithResourceAcl & WithAccessibleAcl) | null> {
  if (!hasAccessibleAcl(resource)) {
    return null;
  }
  const acl = await internal_fetchAcl(resource, options);
  const resourceWithAcl = internal_setAcl(resource, acl);
  let resourceAcl: AclDataset;
  if (hasResourceAcl(resourceWithAcl)) {
    // This is the simple case, where the Resource ACL we need to update already
    // exists.
    resourceAcl = internal_getResourceAcl(resourceWithAcl);
  } else if (hasFallbackAcl(resourceWithAcl)) {
    // In this case, the Resource ACL needs to be created first, and then updated.
    resourceAcl = createAclFromFallbackAcl(resourceWithAcl);
  } else {
    return null;
  }

  return internal_setResourceAcl(resourceWithAcl, resourceAcl);
}

async function saveUpdatedAcl<
  T extends WithServerResourceInfo & WithAccessibleAcl & WithResourceAcl
>(
  resource: T,
  acl: AclDataset,
  options: Partial<typeof internal_defaultFetchOptions>
): Promise<T | null> {
  let savedAcl: AclDataset | null = null;
  try {
    savedAcl = await saveAclFor(resource, acl, options);
    return internal_setResourceAcl(resource, savedAcl);
  } catch (e) {
    return null;
  }
}

async function setActorClassAccess<T extends WithServerResourceInfo>(
  resource: T,
  access: Partial<WacAccess>,
  getAccess: typeof getPublicAccessWac,
  setAccess: typeof setPublicResourceAccessWac,
  options: Partial<typeof internal_defaultFetchOptions>
): Promise<(T & WithResourceAcl) | null> {
  const resourceWithOldAcl = await prepareResourceAcl(resource, options);

  if (resourceWithOldAcl === null) {
    return null;
  }

  const resourceAcl = getResourceAcl(resourceWithOldAcl);
  const currentAccess = getAccess(resourceWithOldAcl) as AclAccess;
  const wacAccess = universalAccessToAcl(access, currentAccess);
  const updatedResourceAcl = setAccess(resourceAcl, wacAccess);

  return await saveUpdatedAcl(resourceWithOldAcl, updatedResourceAcl, options);
}

async function setActorAccess<T extends WithServerResourceInfo>(
  resource: T,
  actor: UrlString,
  access: Partial<WacAccess>,
  getAccess: typeof getAgentAccessWac,
  setAccess: typeof setAgentResourceAccessWac,
  options: Partial<typeof internal_defaultFetchOptions>
): Promise<(T & WithResourceAcl) | null> {
  const resourceWithOldAcl = await prepareResourceAcl(resource, options);

  if (resourceWithOldAcl === null) {
    return null;
  }

  const currentAccess = getAccess(resourceWithOldAcl, actor) as AclAccess;
  const resourceAcl = getResourceAcl(resourceWithOldAcl);
  const wacAccess = universalAccessToAcl(access, currentAccess);
  const updatedResourceAcl = setAccess(resourceAcl, actor, wacAccess);

  return await saveUpdatedAcl(resourceWithOldAcl, updatedResourceAcl, options);
}

/**
 * Set the Access modes for a given Agent to a given Resource.
 *
 * Important note: if the target resource did not have a Resource ACL, and its
 * Access was regulated by its Fallback ACL, said Fallback ACL is copied to create
 * a new Resource ACL. This has the side effect that the next time the Fallback
 * ACL is updated, the changes _will not impact_ the target resource.
 *
 * If the target Resource's Access mode cannot be determined, e.g. the user does
 * not have Read and Write access to the target Resource's ACL, or to its
 * fallback ACL if it does not have a Resource ACL, then `null` is returned.
 *
 * @param resource The Resource for which Access is being set
 * @param agent The Agent for whom Access is being set
 * @param access The Access being set
 * @param options Optional parameter `options.fetch`: An alternative `fetch` function to make the HTTP request, compatible with the browser-native [fetch API](https://developer.mozilla.org/docs/Web/API/WindowOrWorkerGlobalScope/fetch#parameters).
 * @returns The Resource, with its ACL updated, or null if the new Access could not
 * be set.
 */
export async function setAgentResourceAccess<T extends WithServerResourceInfo>(
  resource: T,
  agent: WebId,
  access: Partial<WacAccess>,
  options: Partial<
    typeof internal_defaultFetchOptions
  > = internal_defaultFetchOptions
): Promise<(T & WithResourceAcl) | null> {
  return await setActorAccess(
    resource,
    agent,
    access,
    getAgentAccessWac,
    setAgentResourceAccessWac,
    options
  );
}

/**
 * Set the Access modes for a given Group to a given Resource.
 *
 * Important note: if the target resource did not have a Resource ACL, and its
 * Access was regulated by its Fallback ACL, said Fallback ACL is copied to create
 * a new Resource ACL. This has the side effect that the next time the Fallback
 * ACL is updated, the changes _will not impact_ the target resource.
 *
 * If the target Resource's Access mode cannot be determined, e.g. the user does
 * not have Read and Write access to the target Resource's ACL, or to its
 * fallback ACL if it does not have a Resource ACL, then `null` is returned.
 *
 * @param resource The Resource for which Access is being set
 * @param agent The Group for which Access is being set
 * @param access The Access being set
 * @param options Optional parameter `options.fetch`: An alternative `fetch` function to make the HTTP request, compatible with the browser-native [fetch API](https://developer.mozilla.org/docs/Web/API/WindowOrWorkerGlobalScope/fetch#parameters).
 * @returns The Resource, with its ACL updated, or null if the new Access could not
 * be set.
 */
export async function setGroupResourceAccess<T extends WithServerResourceInfo>(
  resource: T,
  group: UrlString,
  access: Partial<WacAccess>,
  options: Partial<
    typeof internal_defaultFetchOptions
  > = internal_defaultFetchOptions
): Promise<(T & WithResourceAcl) | null> {
  return await setActorAccess(
    resource,
    group,
    access,
    getGroupAccessWac,
    setGroupResourceAccessWac,
    options
  );
}

/**
 * Set the Access modes for everyone to a given Resource.
 *
 * Important note: if the target resource did not have a Resource ACL, and its
 * Access was regulated by its Fallback ACL, said Fallback ACL is copied to create
 * a new Resource ACL. This has the side effect that the next time the Fallback
 * ACL is updated, the changes _will not impact_ the target resource.
 *
 * If the target Resource's Access mode cannot be determined, e.g. the user does
 * not have Read and Write access to the target Resource's ACL, or to its
 * fallback ACL if it does not have a Resource ACL, then `null` is returned.
 *
 * @param resource The Resource for which Access is being set
 * @param access The Access being set
 * @param options Optional parameter `options.fetch`: An alternative `fetch` function to make the HTTP request, compatible with the browser-native [fetch API](https://developer.mozilla.org/docs/Web/API/WindowOrWorkerGlobalScope/fetch#parameters).
 * @returns The Resource, with its ACL updated, or null if the new Access could not
 * be set.
 */
export async function setPublicResourceAccess<T extends WithServerResourceInfo>(
  resource: T,
  access: Partial<WacAccess>,
  options: Partial<
    typeof internal_defaultFetchOptions
  > = internal_defaultFetchOptions
): Promise<(T & WithResourceAcl) | null> {
  return await setActorClassAccess(
    resource,
    access,
    getPublicAccessWac,
    setPublicResourceAccessWac,
    options
  );
}