import { DateTime, FixedOffsetZone, Zone } from "~/shared/utils/luxon";
import type {
	ApiSchedule,
	ApiScheduleEvent,
	ApiScheduleEventSlot,
	ApiScheduleLocation,
	ApiScheduleRole,
	ApiScheduleShift,
	ApiScheduleShiftSlot
} from "~/shared/types/api";
import type { Entity, Id, Living, Tombstone } from "~/shared/types/common";
import { arrayEquals, setEquals } from "~/shared/utils/functions";

function filterAlive<T extends Entity>(entities?: T[]) {
	return (entities ?? []).filter((entity) => !entity.deleted) as Living<T>[];
}

function filterTombstone<T extends Entity>(entities?: T[]) {
	return (entities ?? []).filter((entity) => entity.deleted) as Tombstone<T>[];
}

function entityMap<T extends { id: Id }>(entities: T[]) {
	return new Map(entities.map(entity => [entity.id, entity]));
}

export function toIso(timestamp: DateTime) {
	return timestamp.setZone(FixedOffsetZone.utcInstance).toISO();
}

export abstract class ClientEntity {
	constructor(
		public id: Id,
		public updatedAt: DateTime,
		public deleted: boolean,
	) {
	}

	abstract equals(other: this): boolean;
}

export class ClientScheduleLocation extends ClientEntity {
	constructor(
		id: Id,
		updatedAt: DateTime,
		deleted: boolean,
		public name: string,
		public description: string,
	) {
		super(id, updatedAt, deleted);
	}

	clone() {
		return new ClientScheduleLocation(
			this.id,
			this.updatedAt,
			this.deleted,
			this.name,
			this.description,
		);
	}

	equals(other: ClientScheduleLocation) {
		return (
			this.id === other.id
			&& this.updatedAt.toMillis() === other.updatedAt.toMillis()
			&& this.deleted === other.deleted
			&& this.name === other.name
			&& this.description === other.description
		)
	}

	static fromApi(api: Living<ApiScheduleLocation>, opts: { zone: Zone, locale: string }) {
		return new this(
			api.id,
			DateTime.fromISO(api.updatedAt, opts),
			api.deleted ?? false,
			api.name,
			api.description ?? "",
		);
	}

	toApi(): ApiScheduleLocation {
		if (this.deleted) {
			return {
				id: this.id,
				updatedAt: toIso(this.updatedAt),
				deleted: true,
			}
		}
		return {
			id: this.id,
			updatedAt: toIso(this.updatedAt),
			name: this.name,
			description: this.description || undefined,
		}
	}
}

export class ClientScheduleEvent extends ClientEntity {
	constructor(
		id: Id,
		updatedAt: DateTime,
		deleted: boolean,
		public name: string,
		public crew: boolean,
		public host: string,
		public cancelled: boolean,
		public description: string,
		public interested: number,
		public slots: ClientScheduleEventSlot[],
	) {
		super(id, updatedAt, deleted);
	}

	clone() {
		return new ClientScheduleEvent(
			this.id,
			this.updatedAt,
			this.deleted,
			this.name,
			this.crew,
			this.host,
			this.cancelled,
			this.description,
			this.interested,
			this.slots.map(slot => slot.clone()),
		);
	}

	equals(other: ClientScheduleEvent) {
		return (
			this.id === other.id
			&& this.updatedAt.toMillis() === other.updatedAt.toMillis()
			&& this.deleted === other.deleted
			&& this.name === other.name
			&& this.crew === other.crew
			&& this.host === other.host
			&& this.cancelled === other.cancelled
			&& this.description === other.description
			&& this.interested === other.interested
			&& arrayEquals(this.slots, other.slots, (a, b) => a.equals(b))
		)
	}

	static fromApi(
		api: Living<ApiScheduleEvent>,
		locations: Map<Id, ClientScheduleLocation>,
		opts: { zone: Zone, locale: string },
	) {
		return new this(
			api.id,
			DateTime.fromISO(api.updatedAt, opts),
			api.deleted ?? false,
			api.name,
			api.crew ?? false,
			api.host ?? "",
			api.cancelled ?? false,
			api.description ?? "",
			api.interested ?? 0,
			api.slots.map(slot => ClientScheduleEventSlot.fromApi(slot, locations, opts)),
		);
	}

	toApi(): ApiScheduleEvent {
		if (this.deleted) {
			return {
				id: this.id,
				updatedAt: toIso(this.updatedAt),
				deleted: true,
			}
		}
		return {
			id: this.id,
			updatedAt: toIso(this.updatedAt),
			name: this.name,
			crew: this.crew || undefined,
			host: this.host || undefined,
			cancelled: this.cancelled || undefined,
			description: this.description || undefined,
			interested: this.interested || undefined,
			slots: this.slots.map(slot => slot.toApi()),
		}
	}
}

export class ClientScheduleEventSlot {
	constructor(
		public id: Id,
		public start: DateTime,
		public end: DateTime,
		public locations: ClientScheduleLocation[],
		public assigned: Set<Id>,
		public interested: number,
	) {
	}

	clone() {
		return new ClientScheduleEventSlot(
			this.id,
			this.start,
			this.end,
			[...this.locations],
			new Set(this.assigned),
			this.interested,
		);
	}

	equals(other: ClientScheduleEventSlot) {
		return (
			this.id === other.id
			&& this.start.toMillis() === other.start.toMillis()
			&& this.end.toMillis() === other.end.toMillis()
			&& arrayEquals(this.locations, other.locations)
			&& setEquals(this.assigned, other.assigned)
			&& this.interested === other.interested
		)
	}

	static fromApi(
		api: ApiScheduleEventSlot,
		locations: Map<Id, ClientScheduleLocation>,
		opts: { zone: Zone, locale: string }
	) {
		return new this(
			api.id,
			DateTime.fromISO(api.start, opts),
			DateTime.fromISO(api.end, opts),
			api.locationIds.map(id => locations.get(id)!),
			new Set(api.assigned),
			api.interested ?? 0,
		);
	}

	toApi(): ApiScheduleEventSlot {
		return {
			id: this.id,
			start: toIso(this.start),
			end: toIso(this.end),
			locationIds: this.locations.map(location => location.id),
			assigned: this.assigned.size ? [...this.assigned] : undefined,
			interested: this.interested || undefined,
		}
	}
}

export class ClientScheduleRole extends ClientEntity {
	constructor(
		id: Id,
		updatedAt: DateTime,
		deleted: boolean,
		public name: string,
		public description: string,
	) {
		super(id, updatedAt, deleted);
	}

	clone() {
		return new ClientScheduleRole(
			this.id,
			this.updatedAt,
			this.deleted,
			this.name,
			this.description,
		);
	}

	equals(other: ClientScheduleRole) {
		return (
			this.id === other.id
			&& this.updatedAt.toMillis() === other.updatedAt.toMillis()
			&& this.deleted === other.deleted
			&& this.name === other.name
			&& this.description === other.description
		)
	}

	static fromApi(api: Living<ApiScheduleRole>, opts: { zone: Zone, locale: string }) {
		return new this(
			api.id,
			DateTime.fromISO(api.updatedAt, opts),
			api.deleted ?? false,
			api.name,
			api.description ?? "",
		);
	}

	toApi(): ApiScheduleRole {
		if (this.deleted) {
			return {
				id: this.id,
				updatedAt: toIso(this.updatedAt),
				deleted: true,
			}
		}
		return {
			id: this.id,
			updatedAt: toIso(this.updatedAt),
			name: this.name,
			description: this.description || undefined,
		}
	}
}

export class ClientScheduleShift extends ClientEntity {
	constructor(
		id: Id,
		updatedAt: DateTime,
		deleted: boolean,
		public role: ClientScheduleRole,
		public name: string,
		public description: string,
		public slots: ClientScheduleShiftSlot[],
	) {
		super(id, updatedAt, deleted);
	}

	clone() {
		return new ClientScheduleShift(
			this.id,
			this.updatedAt,
			this.deleted,
			this.role,
			this.name,
			this.description,
			this.slots.map(slot => slot.clone()),
		)
	}

	equals(other: ClientScheduleShift) {
		return (
			this.id === other.id
			&& this.updatedAt.toMillis() === other.updatedAt.toMillis()
			&& this.deleted === other.deleted
			&& this.role.id === other.role.id
			&& this.name === other.name
			&& this.description === other.description
			&& arrayEquals(this.slots, other.slots, (a, b) => a.equals(b))
		)
	}

	static fromApi(
		api: Living<ApiScheduleShift>,
		roles: Map<Id, ClientScheduleRole>,
		opts: { zone: Zone, locale: string },
	) {
		return new this(
			api.id,
			DateTime.fromISO(api.updatedAt, opts),
			api.deleted ?? false,
			roles.get(api.roleId)!,
			api.name,
			api.description ?? "",
			api.slots.map(slot => ClientScheduleShiftSlot.fromApi(slot, opts)),
		);
	}

	toApi(): ApiScheduleShift {
		if (this.deleted) {
			return {
				id: this.id,
				updatedAt: toIso(this.updatedAt),
				deleted: true,
			}
		}
		return {
			id: this.id,
			updatedAt: toIso(this.updatedAt),
			roleId: this.role.id,
			name: this.name,
			description: this.description || undefined,
			slots: this.slots.map(slot => slot.toApi()),
		}
	}
}

export class ClientScheduleShiftSlot {
	constructor(
		public id: Id,
		public start: DateTime,
		public end: DateTime,
		public assigned: Set<Id>,
	) {
	}

	clone() {
		return new ClientScheduleShiftSlot(
			this.id,
			this.start,
			this.end,
			new Set(this.assigned),
		)
	}

	equals(other: ClientScheduleShiftSlot) {
		return (
			this.id === other.id
			&& this.start.toMillis() === other.start.toMillis()
			&& this.end.toMillis() === other.end.toMillis()
			&& setEquals(this.assigned, other.assigned)
		)
	}

	static fromApi(api: ApiScheduleShiftSlot, opts: { zone: Zone, locale: string }) {
		return new this(
			api.id,
			DateTime.fromISO(api.start, opts),
			DateTime.fromISO(api.end, opts),
			new Set(api.assigned),
		);
	}

	toApi(): ApiScheduleShiftSlot {
		return {
			id: this.id,
			start: toIso(this.start),
			end: toIso(this.end),
			assigned: this.assigned.size ? [...this.assigned] : undefined,
		}
	}
}

export class ClientSchedule extends ClientEntity {
	originalLocations: Map<Id, ClientScheduleLocation>;
	originalEvents: Map<Id, ClientScheduleEvent>;
	originalRoles: Map<Id, ClientScheduleRole>;
	originalShifts: Map<Id, ClientScheduleShift>;
	modified: boolean;

	constructor(
		id: 111,
		updatedAt: DateTime,
		deleted: boolean,
		public locations: Map<Id, ClientScheduleLocation>,
		public events: Map<Id, ClientScheduleEvent>,
		public roles: Map<Id, ClientScheduleRole>,
		public shifts: Map<Id, ClientScheduleShift>,
	) {
		super(id, updatedAt, deleted);
		this.originalLocations = new Map(locations);
		this.originalEvents = new Map(events);
		this.originalRoles = new Map(roles);
		this.originalShifts = new Map(shifts);
		this.modified = false;
	}

	equals(other: ClientSchedule): boolean {
		throw new Error("ClientSchedule.equals not implemented")
	}

	private recalcModified() {
		function mapEquals<K, V>(a: Map<K, V>, b: Map<K, V>) {
			if (a.size !== b.size) {
				return false;
			}
			for (const [key, value] of a) {
				if (!b.has(key) || b.get(key) !== value) {
					return false;
				}
			}
			return true;
		}
		this.modified = (
			!mapEquals(this.locations, this.originalLocations)
			|| !mapEquals(this.events, this.originalEvents)
			|| !mapEquals(this.roles, this.originalRoles)
			|| !mapEquals(this.shifts, this.originalShifts)
		);
	}

	private fixLocationRefs(locations: Map<Id, ClientScheduleLocation>) {
		for (const events of [this.events, this.originalEvents]) {
			for (const event of events.values()) {
				for (const slot of event.slots) {
					for (let i = 0; i < slot.locations.length; i++) {
						const location = locations.get(slot.locations[i].id);
						if (location && slot.locations[i] !== location) {
							slot.locations[i] = location;
						}
					}
				}
			}
		}
	}

	private checkLocationRefsForDeletion(id: Id) {
		for (const event of this.events.values()) {
			for (const slot of event.slots) {
				for (let i = 0; i < slot.locations.length; i++) {
					if (slot.locations[i].id === id) {
						throw new Error(`Cannot delete location, event "${event.name}" depends on it`);
					}
				}
			}
		}
	}

	isModifiedLocation(id: Id) {
		return this.originalLocations.get(id) !== this.locations.get(id);
	}

	setLocation(location: ClientScheduleLocation) {
		if (location.deleted) {
			this.checkLocationRefsForDeletion(location.id);
		}
		this.locations.set(location.id, location);
		if (!location.deleted) {
			this.fixLocationRefs(new Map([[location.id, location]]));
		}
		this.modified = true;
	}

	editLocation(
		location: ClientScheduleLocation,
		edits: {
			deleted?: boolean,
			name?: string,
			description?: string
		},
	) {
		const copy = location.clone();
		if (edits.deleted !== undefined) copy.deleted = edits.deleted;
		if (edits.name !== undefined) copy.name = edits.name;
		if (edits.description !== undefined) copy.description = edits.description;
		this.setLocation(copy);
	}

	restoreLocation(id: Id) {
		const location = this.originalLocations.get(id);
		if (location) {
			this.locations.set(id, location);
			this.fixLocationRefs(new Map([[location.id, location]]));
		} else {
			this.checkLocationRefsForDeletion(id);
			this.locations.delete(id);
		}
		this.recalcModified();
	}

	isModifiedEvent(id: Id) {
		return this.originalEvents.get(id) !== this.events.get(id);
	}

	setEvent(event: ClientScheduleEvent) {
		this.events.set(event.id, event);
		this.modified = true;
	}

	editEvent(
		event: ClientScheduleEvent,
		edits: {
			deleted?: boolean,
			name?: string,
			description?: string
		},
	) {
		const copy = event.clone();
		if (edits.deleted !== undefined) copy.deleted = edits.deleted;
		if (edits.name !== undefined) copy.name = edits.name;
		if (edits.description !== undefined) copy.description = edits.description;
		this.setEvent(copy);
	}

	restoreEvent(id: Id) {
		const event = this.originalEvents.get(id);
		if (event) {
			this.events.set(id, event);
		} else {
			this.events.delete(id);
		}
		this.recalcModified();
	}

	private fixRoleRefs(roles: Map<Id, ClientScheduleRole>) {
		for (const shifts of [this.shifts, this.originalShifts]) {
			for (const shift of shifts.values()) {
				const role = roles.get(shift.role.id);
				if (role && shift.role !== role) {
					shift.role = role;
				}
			}
		}
	}

	private checkRoleRefsForDeletion(id: Id) {
		for (const shift of this.shifts.values()) {
			if (shift.role.id === id) {
				throw new Error(`Cannot delete role, shift "${shift.name}" depends on it`);
			}
		}
	}

	isModifiedRole(id: Id) {
		return this.originalRoles.get(id) !== this.roles.get(id);
	}

	setRole(role: ClientScheduleRole) {
		if (role.deleted) {
			this.checkRoleRefsForDeletion(role.id);
		}
		this.roles.set(role.id, role);
		if (!role.deleted) {
			this.fixRoleRefs(new Map([[role.id, role]]));
		}
		this.modified = true;
	}

	editRole(
		role: ClientScheduleRole,
		edits: {
			deleted?: boolean,
			name?: string,
			description?: string
		},
	) {
		const copy = role.clone();
		if (edits.deleted !== undefined) copy.deleted = edits.deleted;
		if (edits.name !== undefined) copy.name = edits.name;
		if (edits.description !== undefined) copy.description = edits.description;
		this.setRole(copy);
	}

	restoreRole(id: Id) {
		const role = this.originalRoles.get(id);
		if (role) {
			this.roles.set(id, role);
			this.fixRoleRefs(new Map([[role.id, role]]));
		} else {
			this.checkRoleRefsForDeletion(id);
			this.roles.delete(id);
		}
		this.recalcModified();
	}

	isModifiedShift(id: Id) {
		return this.originalShifts.get(id) !== this.shifts.get(id);
	}

	setShift(shift: ClientScheduleShift) {
		this.shifts.set(shift.id, shift);
		this.modified = true;
	}

	editShift(
		shift: ClientScheduleShift,
		edits: {
			deleted?: boolean,
			name?: string,
			description?: string
		},
	) {
		const copy = shift.clone();
		if (edits.deleted !== undefined) copy.deleted = edits.deleted;
		if (edits.name !== undefined) copy.name = edits.name;
		if (edits.description !== undefined) copy.description = edits.description;
		this.setShift(copy);
	}

	restoreShift(id: Id) {
		const shift = this.originalShifts.get(id);
		if (shift) {
			this.shifts.set(id, shift);
		} else {
			this.shifts.delete(id);
		}
		this.recalcModified();
	}

	static fromApi(api: Living<ApiSchedule>, opts: { zone: Zone, locale: string }) {
		const locations = entityMap(filterAlive(api.locations).map(location => ClientScheduleLocation.fromApi(location, opts)));
		const roles = entityMap(filterAlive(api.roles).map(role => ClientScheduleRole.fromApi(role, opts)));
		return new this(
			api.id,
			DateTime.fromISO(api.updatedAt, opts),
			api.deleted ?? false,
			locations,
			entityMap(filterAlive(api.events).map(event => ClientScheduleEvent.fromApi(event, locations, opts))),
			roles,
			entityMap(filterAlive(api.shifts).map(shift => ClientScheduleShift.fromApi(shift, roles, opts))),
		);
	}

	toApi(diff: boolean): ApiSchedule {
		if (this.deleted) {
			return {
				id: this.id,
				updatedAt: toIso(this.updatedAt),
				deleted: true,
			}
		}
		if (!diff) {
			return {
				id: this.id as 111,
				updatedAt: toIso(this.updatedAt),
				locations: this.locations.size ? [...this.locations.values()].map(location => location.toApi()) : undefined,
				events: this.events.size ? [...this.events.values()].map(event => event.toApi()) : undefined,
				roles: this.roles.size ? [...this.roles.values()].map(role => role.toApi()) : undefined,
				shifts: this.shifts.size ? [...this.shifts.values()].map(shift => shift.toApi()) : undefined,
			}
		}

		const locations: ApiScheduleLocation[] = [];
		for (const [id, location] of this.locations)
			if (location !== this.originalLocations.get(id)) locations.push(location.toApi());
		const events: ApiScheduleEvent[] = [];
		for (const [id, event] of this.events)
			if (event !== this.originalEvents.get(id)) events.push(event.toApi());
		const roles: ApiScheduleRole[] = [];
		for (const [id, role] of this.roles)
			if (role !== this.originalRoles.get(id)) roles.push(role.toApi());
		const shifts: ApiScheduleShift[] = [];
		for (const [id, shift] of this.shifts)
			if (shift !== this.originalShifts.get(id)) shifts.push(shift.toApi());
		return {
			id: this.id as 111,
			updatedAt: toIso(this.updatedAt),
			locations: locations.length ? locations : undefined,
			events: events.length ? events : undefined,
			roles: roles.length ? roles : undefined,
			shifts: shifts.length ? shifts : undefined,
		}
	}

	applyUpdate(update: ApiSchedule, opts: { zone: Zone, locale: string }) {
		if (update.deleted)
			throw new Error("ClientSchedule.applyUpdate: Unexpected deletion");
		if (update.id !== this.id)
			throw new Error("ClientSchedule.applyUpdate: id mismatch");
		this.updatedAt = DateTime.fromISO(update.updatedAt, opts);

		function applyEntityUpdates<T extends Entity, U extends ClientEntity>(
			entityUpdates: T[] | undefined,
			fromApi: (api: Living<T>) => U,
			originalEntities: Map<Id, U>,
			entities: Map<Id, U>,
		) {
			if (!entityUpdates)
				return new Map();
			const setEntites = entityMap(filterAlive(entityUpdates).map(entity => fromApi(entity)));
			for (const [id, updatedLocation] of setEntites) {
				const modifiedLocation = entities.get(id);
				if (
					originalEntities.get(id) === modifiedLocation
					|| modifiedLocation?.equals(updatedLocation)
				) {
					entities.set(id, updatedLocation);
				}
				originalEntities.set(id, updatedLocation);
			}
			const deletedLocations = filterTombstone(entityUpdates).map(location => location.id);
			for (const id of deletedLocations) {
				const modifiedLocation = entities.get(id);
				if (
					originalEntities.get(id) === modifiedLocation
					|| entities.get(id)?.deleted
				) {
					entities.delete(id);
				}
				originalEntities.delete(id);
			}
			return setEntites;
		}

		const setLocations = applyEntityUpdates(
			update.locations,
			api => ClientScheduleLocation.fromApi(api, opts),
			this.originalLocations,
			this.locations,
		);
		this.fixLocationRefs(setLocations);
		applyEntityUpdates(
			update.events,
			api => ClientScheduleEvent.fromApi(api, this.locations, opts),
			this.originalEvents,
			this.events,
		);
		applyEntityUpdates(
			update.roles,
			api => ClientScheduleRole.fromApi(api, opts),
			this.originalRoles,
			this.roles,
		);
		applyEntityUpdates(
			update.shifts,
			api => ClientScheduleShift.fromApi(api, this.roles, opts),
			this.originalShifts,
			this.shifts,
		);
		this.recalcModified();
	}
}