const keyMap = {
	datePrecision: 'date_precision',
	productionDate: 'production_date',
	productionLocation: 'production_location',
	productionCity: 'production_city',
	productionState: 'production_state',
};

export default function initSceneRevisions({ knex, mj, logger }) {
	async function applySceneValueDelta(sceneId, delta, trx) {
		return knex('releases')
			.where('id', sceneId)
			.update(keyMap[delta.key] || delta.key, delta.value)
			.transacting(trx);
	}

	async function applySceneActorsDelta(sceneId, delta, trx) {
		await knex('releases_actors')
			.where('release_id', sceneId)
			.delete()
			.transacting(trx);

		if (delta.value.length > 0) {
			await knex('releases_actors')
				.insert(delta.value.map((actorId) => ({
					release_id: sceneId,
					actor_id: actorId,
				})))
				.transacting(trx);
		}
	}

	async function applySceneTagsDelta(sceneId, delta, trx) {
		// don't remove unidentified tags
		await knex('releases_tags')
			.where('release_id', sceneId)
			.whereNotNull('tag_id')
			.delete()
			.transacting(trx);

		if (delta.value.length > 0) {
			await knex('releases_tags')
				.insert(delta.value.map((tag) => ({
					release_id: sceneId,
					tag_id: tag.id,
					actor_id: tag.actorId,
					source: 'editor',
				})))
				.transacting(trx);
		}
	}

	async function applySceneMoviesDelta(sceneId, delta, trx) {
		await knex('movies_scenes')
			.where('scene_id', sceneId)
			.delete()
			.transacting(trx);

		if (delta.value.length > 0) {
			await knex('movies_scenes')
				.insert(delta.value.map((movieId) => ({
					scene_id: sceneId,
					movie_id: movieId,
				})))
				.transacting(trx);
		}
	}

	async function applySceneDeleteDelta(sceneId, _delta, trx, reqUser) {
		if (!reqUser.abilities.some((ability) => ability.subject === 'scene' && ability.action === 'delete')) {
			throw new HttpError('You are not privileged to delete scenes', 400);
		}

		await knex('releases')
			.where('id', sceneId)
			.delete()
			.transacting(trx);
	}

	async function applySceneRevision(revisionIds, reqUser) {
		const revisions = await knex('scenes_revisions')
			.whereIn('id', revisionIds)
			.whereNull('applied_at'); // should not re-apply revision that was already applied

		await revisions.reduce(async (chain, revision) => {
			await chain;

			await knex.transaction(async (trx) => {
				await Promise.all(revision.deltas.map(async (delta) => {
					if (delta.key === 'delete') {
						return applySceneDeleteDelta(revision.scene_id, delta, trx, reqUser);
					}

					if ([
						'title',
						'description',
						'date',
						'datePrecision',
						'duration',
						'productionDate',
						'productionLocation',
						'productionCity',
						'productionState',
					].includes(delta.key)) {
						return applySceneValueDelta(revision.scene_id, delta, trx);
					}

					if (delta.key === 'actors') {
						return applySceneActorsDelta(revision.scene_id, delta, trx);
					}

					if (delta.key === 'tags') {
						return applySceneTagsDelta(revision.scene_id, delta, trx);
					}

					if (delta.key === 'movies') {
						return applySceneMoviesDelta(revision.scene_id, delta, trx);
					}

					return null;
				}));

				await knex('scenes_revisions')
					.where('id', revision.id)
					.update('applied_at', knex.fn.now())
					.transacting(trx);

				// await trx.commit();
			}).catch(async (error) => {
				logger.error(`Failed to apply revision ${revision.id} on scene ${revision.scene_id}: ${error.message}`);
				throw error;
			});
		}, Promise.resolve());
	}

	async function reviewSceneRevision(revisionId, isApproved, { feedback }, reqUser) {
		if (!reqUser || reqUser.role === 'user') {
			throw new HttpError('You are not permitted to approve revisions', 403);
		}

		if (typeof isApproved !== 'boolean') {
			throw new HttpError('You must either approve or reject the revision', 400);
		}

		const updated = await knex('scenes_revisions')
			.where('id', revisionId)
			.whereNull('approved') // don't rerun reviewed revision, must be forked into new revision instead
			.whereNull('applied_at')
			.update({
				approved: isApproved,
				reviewed_at: knex.fn.now(),
				reviewed_by: reqUser.id,
				feedback,
			});

		if (updated === 0) {
			throw new HttpError('This revision was already reviewed', 409);
		}

		if (isApproved) {
			try {
				await applySceneRevision([revisionId], reqUser);
			} catch (error) {
				await knex('scenes_revisions')
					.where('id', revisionId)
					.update({
						approved: null,
						reviewed_at: null,
						reviewed_by: null,
					});

				throw error;
			}
		}
	}

	async function createSceneRevision(sceneId, { edits, comment, apply }, reqUser) {
		const [
			[scene],
			openRevisions,
		] = await Promise.all([
			fetchScenesById([sceneId], {
				reqUser,
				includeAssets: true,
				includePartOf: true,
			}),
			knex('scenes_revisions')
				.where('user_id', reqUser.id)
				.whereNull('approved'),
		]);

		if (!scene) {
			throw new HttpError(`No scene with ID ${sceneId} found to update`, 404);
		}

		if (openRevisions.length >= config.revisions.unapprovedLimit && reqUser.role !== 'admin') {
			throw new HttpError(`You have ${config.revisions.unapprovedLimit} unapproved revisions, please wait for approval before submitting another revision.`, 429);
		}

		const baseScene = Object.fromEntries(Object.entries(scene).map(([key, values]) => {
			if ([
				'effectiveDate',
				'isNew',
				'network',
				'stashes',
				'watchUrl',
			].includes(key)) {
				return null;
			}

			if (values?.hash) {
				return [key, values.hash];
			}

			if (values?.id) {
				return [key, values.id];
			}

			if (key === 'tags') {
				return [key, values.map((tag) => ({
					id: tag.id,
					actorId: tag.actorId,
				}))];
			}

			if (Array.isArray(values)) {
				return [key, values.map((value) => value?.hash || value?.id || value)];
			}

			return [key, values];
		}).filter(Boolean));

		const deltas = Object.entries(edits).map(([key, value]) => {
			if (key === 'delete') {
				return { key: 'delete' };
			}

			if (baseScene[key] === value || typeof value === 'undefined') {
				return null;
			}

			if (key === 'tags') {
				return {
					key,
					value: value.map((tag) => ({
						id: tag.id,
						actorId: tag.actorId,
					})),
				};
			}

			if (Array.isArray(value)) {
				const valueSet = new Set(value);
				const baseSet = new Set(baseScene[key]);

				if (valueSet.size === baseSet.size && baseScene[key].every((id) => valueSet.has(id))) {
					return null;
				}

				return { key, value: Array.from(valueSet) };
			}

			return { key, value };
		}).filter(Boolean);

		if (deltas.length === 0) {
			throw new HttpError('No effective changes provided', 400);
		}

		const [revisionEntry] = await knex('scenes_revisions')
			.insert({
				user_id: reqUser.id,
				scene_id: scene.id,
				base: JSON.stringify(baseScene),
				deltas: JSON.stringify(deltas),
				hash: mj.hash({
					base: baseScene,
					deltas,
				}),
				comment,
			})
			.returning('id');

		if (['admin', 'editor'].includes(reqUser.role) && apply) {
			// don't keep the editor waiting for the revision to apply
			reviewSceneRevision(revisionEntry.id, true, {}, reqUser).catch(() => {});
		}
	}

	return {
		createSceneRevision,
		reviewSceneRevision,
	};
}