import type { AniListAuthorisation } from './identity';
import type { MediaTitle } from './media';

export interface MediaPrequel {
	id: number;
	title: MediaTitle;
	episodes: number;
	seen: number;
}

interface PrequelRelations {
	edges: {
		relationType: string;
		node: {
			title: MediaTitle;
			episodes: number;
			mediaListEntry: {
				status: string;
				progress: number;
			};
		};
	}[];
}

interface PrequelsPage {
	data: {
		Page: {
			media: {
				title: MediaTitle;
				id: number;
				relations: PrequelRelations;
			}[];
			pageInfo: {
				hasNextPage: boolean;
			};
		};
	};
}

const prequelsPage = async (
	page: number,
	anilistAuthorisation: AniListAuthorisation,
	year: number,
	season: 'WINTER' | 'SPRING' | 'SUMMER' | 'FALL'
): Promise<PrequelsPage> =>
	await (
		await fetch('https://graphql.anilist.co', {
			method: 'POST',
			headers: {
				Authorization: `${anilistAuthorisation.tokenType} ${anilistAuthorisation.accessToken}`,
				'Content-Type': 'application/json',
				Accept: 'application/json'
			},
			body: JSON.stringify({
				query: `{
  Page(page: ${page}) {
    pageInfo {
      hasNextPage
    }
    media(season: ${season}, seasonYear: ${year}) {
      title {
        english
        romaji
      }
      id
      relations {
        edges {
          relationType
          node {
            title {
              english
              romaji
            }
            episodes
            mediaListEntry {
              status
              progress
            }
          }
        }
      }
    }
  }
}`
			})
		})
	).json();

export const prequels = async (
	anilistAuthorisation: AniListAuthorisation,
	year: number,
	season: 'WINTER' | 'SPRING' | 'SUMMER' | 'FALL'
): Promise<MediaPrequel[]> => {
	const candidates = [];
	let page = 1;
	let currentPage = await prequelsPage(page, anilistAuthorisation, year, season);

	for (const candidate of currentPage.data.Page.media) {
		candidates.push(candidate);
	}

	while (currentPage['data']['Page']['pageInfo']['hasNextPage']) {
		for (const candidate of currentPage.data.Page.media) {
			candidates.push(candidate);
		}

		page += 1;
		currentPage = await prequelsPage(page, anilistAuthorisation, year, season);
	}

	const media: MediaPrequel[] = [];

	for (const candidate of candidates) {
		let episodes = 0;
		let seen = 0;

		for (const relation of candidate.relations.edges) {
			if (relation.relationType === 'PREQUEL') {
				if (
					relation.node.mediaListEntry === null ||
					relation.node.mediaListEntry.status !== 'COMPLETED'
				) {
					episodes += relation.node.episodes;

					if (relation.node.mediaListEntry !== null) {
						seen += relation.node.mediaListEntry.progress || 0;
					}
				}
			}
		}

		if (media.some((m) => m.id === candidate.id)) continue;

		if (episodes !== 0) {
			media.push({
				id: candidate.id,
				title: candidate.title,
				episodes,
				seen
			});
		}
	}

	return media;
};