import {
  BusinessRuleError,
  ForbiddenError,
  VersionedAggregateRoot,
  assertThat,
} from '@task-stream/api/shared/domain';
import { ProjectCreatedEvent } from '../events/project-created.event';
import { ProjectDeletedEvent } from '../events/project-deleted.event';
import { ProjectMemberAddedEvent } from '../events/project-member-added.event';
import { ProjectMemberRemovedEvent } from '../events/project-member-removed.event';
import { ProjectMemberRoleChangedEvent } from '../events/project-member-role-changed.event';
import { ProjectSettingsChangedEvent } from '../events/project-settings-changed.event';
import { ProjectUpdatedEvent } from '../events/project-updated.event';
import { ProjectRole } from './project-role';
import {
  defaultProjectSettings,
  ProjectSettings,
  ProjectWorkflow,
  validateProjectSettings,
} from './project-settings';

export interface ProjectMember {
  userId: string;
  role: ProjectRole;
}

/** Data of a project (what ProjectCreatedEvent carries). */
export interface ProjectProps {
  id: string;
  key: string;
  name: string;
  description: string | null;
  /** Anyone (even without signing in) can read it. Absent in old projects: private. */
  isPublic?: boolean;
  /**
   * Takes bug reports and ideas from anyone, through a public form (only
   * while it is public). Absent in old projects: no.
   */
  acceptsProposals?: boolean;
  ownerId: string;
  members: ProjectMember[];
  /** Absent in projects created before settings existed: defaults apply. */
  settings?: ProjectSettings;
  createdAt: string;
  updatedAt: string;
}

/**
 * Event-sourced aggregate: create it with ProjectFactory, load it with the
 * AggregateRehydrator. State only changes in the `on<Event>` handlers.
 */
export class Project extends VersionedAggregateRoot implements ProjectProps {
  public key!: string;
  public name!: string;
  public description: string | null = null;
  public isPublic = false;
  public acceptsProposals = false;
  public ownerId!: string;
  public members: ProjectMember[] = [];
  public settings: ProjectSettings = defaultProjectSettings();
  public createdAt!: string;
  public updatedAt!: string;
  /** Set once deleted: the project can no longer be loaded for commands. */
  public deleted = false;

  constructor(id: string) {
    super();
    this.id = id;
  }

  /** Statuses, transitions, types and areas of this project. */
  get workflow(): ProjectWorkflow {
    return new ProjectWorkflow(this.settings);
  }

  roleOf(userId: string): ProjectRole | null {
    return this.members.find((m) => m.userId === userId)?.role ?? null;
  }

  isMember(userId: string): boolean {
    return this.roleOf(userId) !== null;
  }

  /** Can read the project: members, or anyone if it is public. */
  assertCanView(userId: string): void {
    if (!this.isPublic && !this.isMember(userId)) {
      throw new ForbiddenError(`You are not a member of project ${this.key}`);
    }
  }

  /** Can create and modify tickets, comments, links... (members only, even if public). */
  assertCanContribute(userId: string): void {
    if (!this.isMember(userId)) {
      throw new ForbiddenError(`You are not a member of project ${this.key}`);
    }
    if (this.roleOf(userId) === ProjectRole.VIEWER) {
      throw new ForbiddenError(`Viewers cannot modify project ${this.key}`);
    }
  }

  /** Can manage members, releases and project settings. */
  assertCanManage(userId: string): void {
    const role = this.roleOf(userId);
    if (role !== ProjectRole.OWNER && role !== ProjectRole.ADMIN) {
      throw new ForbiddenError(
        `Only owners and admins can manage project ${this.key}`,
      );
    }
  }

  updateDetails(
    actorId: string,
    changes: {
      name?: string;
      description?: string | null;
      isPublic?: boolean;
      acceptsProposals?: boolean;
    },
  ): void {
    this.assertCanManage(actorId);
    const patch: {
      name?: string;
      description?: string | null;
      isPublic?: boolean;
      acceptsProposals?: boolean;
    } = {};
    if (changes.name !== undefined) {
      const name = changes.name.trim();
      assertThat(name.length > 0, 'Project name is required');
      if (name !== this.name) patch.name = name;
    }
    if (changes.description !== undefined) {
      const description = changes.description?.trim() || null;
      if (description !== this.description) patch.description = description;
    }
    if (changes.isPublic !== undefined && changes.isPublic !== this.isPublic)
      patch.isPublic = changes.isPublic;
    if (
      changes.acceptsProposals !== undefined &&
      changes.acceptsProposals !== this.acceptsProposals
    )
      patch.acceptsProposals = changes.acceptsProposals;
    if (Object.keys(patch).length === 0) return;
    this.apply(new ProjectUpdatedEvent(actorId, this.id, patch));
  }

  /**
   * Only the owner deletes a project, confirming its key. Tickets, comments
   * and releases follow (cascade saga); the events stay in the store.
   */
  delete(actorId: string, confirmKey: string): void {
    if (actorId !== this.ownerId) {
      throw new ForbiddenError(`Only the owner can delete project ${this.key}`);
    }
    if (confirmKey.trim().toUpperCase() !== this.key) {
      throw new BusinessRuleError(
        `Type the project key (${this.key}) to confirm the deletion`,
      );
    }
    this.apply(
      new ProjectDeletedEvent(
        actorId,
        this.id,
        this.key,
        this.members.map((m) => m.userId),
      ),
    );
  }

  /** Owners and admins customise statuses, transitions, types and areas. */
  updateSettings(actorId: string, next: ProjectSettings): void {
    this.assertCanManage(actorId);
    const settings = validateProjectSettings(next, this.settings);
    if (JSON.stringify(settings) === JSON.stringify(this.settings)) return;
    this.apply(new ProjectSettingsChangedEvent(actorId, this.id, settings));
  }

  addMember(actorId: string, userId: string, role: ProjectRole): void {
    this.assertCanManage(actorId);
    assertThat(role !== ProjectRole.OWNER, 'A project can only have one owner');
    if (this.isMember(userId)) {
      throw new BusinessRuleError(
        `User ${userId} is already a member of ${this.key}`,
      );
    }
    this.apply(new ProjectMemberAddedEvent(actorId, this.id, userId, role));
  }

  changeMemberRole(actorId: string, userId: string, role: ProjectRole): void {
    this.assertCanManage(actorId);
    assertThat(role !== ProjectRole.OWNER, 'A project can only have one owner');
    const current = this.roleOf(userId);
    if (!current)
      throw new BusinessRuleError(
        `User ${userId} is not a member of ${this.key}`,
      );
    if (current === ProjectRole.OWNER) {
      throw new BusinessRuleError('The owner role cannot be changed');
    }
    if (current === role) return;
    this.apply(
      new ProjectMemberRoleChangedEvent(
        actorId,
        this.id,
        userId,
        role,
        current,
      ),
    );
  }

  removeMember(actorId: string, userId: string): void {
    // Anyone can leave a project; removing others requires manage rights.
    if (actorId !== userId) this.assertCanManage(actorId);
    if (!this.isMember(userId)) {
      throw new BusinessRuleError(
        `User ${userId} is not a member of ${this.key}`,
      );
    }
    if (userId === this.ownerId) {
      throw new BusinessRuleError('The project owner cannot be removed');
    }
    this.apply(new ProjectMemberRemovedEvent(actorId, this.id, userId));
  }

  /* ---- State transitions (also replayed by loadFromHistory) ---- */

  onProjectCreatedEvent({ project }: ProjectCreatedEvent): void {
    this.key = project.key;
    this.name = project.name;
    this.description = project.description;
    this.isPublic = project.isPublic ?? false;
    this.acceptsProposals = project.acceptsProposals ?? false;
    this.ownerId = project.ownerId;
    this.members = project.members.map((m) => ({ ...m }));
    this.settings = structuredClone(
      project.settings ?? defaultProjectSettings(),
    );
    this.createdAt = project.createdAt;
    this.updatedAt = project.updatedAt;
  }

  onProjectUpdatedEvent(event: ProjectUpdatedEvent): void {
    Object.assign(this, event.changes);
    this.updatedAt = event.occurredAt;
  }

  onProjectDeletedEvent(): void {
    this.deleted = true;
  }

  onProjectSettingsChangedEvent(event: ProjectSettingsChangedEvent): void {
    this.settings = structuredClone(event.settings);
    this.updatedAt = event.occurredAt;
  }

  onProjectMemberAddedEvent(event: ProjectMemberAddedEvent): void {
    this.members = [
      ...this.members,
      { userId: event.userId, role: event.role },
    ];
    this.updatedAt = event.occurredAt;
  }

  onProjectMemberRoleChangedEvent(event: ProjectMemberRoleChangedEvent): void {
    this.members = this.members.map((m) =>
      m.userId === event.userId ? { ...m, role: event.role } : m,
    );
    this.updatedAt = event.occurredAt;
  }

  onProjectMemberRemovedEvent(event: ProjectMemberRemovedEvent): void {
    this.members = this.members.filter((m) => m.userId !== event.userId);
    this.updatedAt = event.occurredAt;
  }
}