import type { AniListAuthorisation } from './identity';
import type { MediaListEntryStatus, MediaSeason, MediaStatus, MediaTitle } from './media';

export interface MediaPrequel {
  id: number;
  title: MediaTitle;
  episodes: number;
  seen: number;
  nextAiringEpisode?: {
    episode: number;
    airingAt?: number;
  };
  startDate: {
    year: number;
    month: number;
    day: number;
  };
  coverImage: {
    extraLarge: string;
    medium: string;
  };
}

export interface PrequelRelationNode {
  id: number;
  title: MediaTitle;
  episodes: number;
  status: MediaStatus;
  mediaListEntry: {
    status: MediaListEntryStatus;
    progress: number;
  };
  coverImage: {
    extraLarge: string;
    medium: string;
  };
  startDate: {
    year: number;
  };
}

export interface PrequelRelation {
  relationType: string;
  node: PrequelRelationNode;
}

export interface PrequelRelations {
  edges: PrequelRelation[];
}

interface PrequelsPage {
  data: {
    Page: {
      media: {
        title: MediaTitle;
        id: number;
        relations: PrequelRelations;
        nextAiringEpisode?: {
          episode: number;
          airingAt?: number;
        };
        startDate: {
          year: number;
          month: number;
          day: number;
        };
        coverImage: {
          extraLarge: string;
          medium: string;
        };
      }[];
      pageInfo: {
        hasNextPage: boolean;
      };
    };
  };
}

const prequelsPage = async (
  page: number,
  anilistAuthorisation: AniListAuthorisation,
  year: number,
  season: MediaSeason
): 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
      }
			coverImage { extraLarge medium }
      id
			nextAiringEpisode { episode airingAt }
			startDate { year month day }
      relations {
        edges {
          relationType
          node {
            title {
              english
              romaji
            }
            episodes
            mediaListEntry {
              status
              progress
            }
						coverImage { extraLarge medium }
          }
        }
      }
    }
  }
}`
      })
    })
  ).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);
  }

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

  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' || relation.relationType === 'PARENT') {
        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,
        nextAiringEpisode: candidate.nextAiringEpisode,
        startDate: candidate.startDate,
        coverImage: candidate.coverImage
      });
  }

  return media;
};