import { useCallback, useEffect, useRef, useState } from 'react';
import { ApiError, request } from './client';
import type { components } from './generated/v1';

export type PlayoutSummary = components['schemas']['PlayoutListItemResponseModel'];
export type PlayoutDetail = components['schemas']['PlayoutResponseModel'];
export type PlayoutItem = components['schemas']['PlayoutItemResponseModel'];
export type PlayoutsPage = components['schemas']['PagedPlayoutsResponseModel'];
export type PlayoutItemsPage = components['schemas']['PagedPlayoutItemsResponseModel'];
export type PlayoutChannelState = components['schemas']['ChannelStateResponseModel'];
export type PlayoutScheduleKind = components['schemas']['PlayoutScheduleKind'];
export type CreatePlayoutRequest = components['schemas']['CreatePlayoutRequest'];
export type UpdatePlayoutDetailsRequest = components['schemas']['UpdatePlayoutDetailsRequest'];

export interface PlayoutsScreenData {
  channelStates: PlayoutChannelState[];
  items: PlayoutItem[];
  playout: PlayoutDetail | null;
  playouts: PlayoutSummary[];
  selectedPlayoutId: number | null;
  totalCount: number;
  warningsCount: number;
}

type PlayoutsScreenBase = Omit<PlayoutsScreenData, 'items' | 'playout'>;

export type PlayoutsScreenQueryState =
  | {
      data: PlayoutsScreenData;
      error: null;
      itemsLoading: boolean;
      refresh: () => void;
      setActivePlayout: (playoutId: number) => void;
      setShowFiller: (showFiller: boolean) => void;
      showFiller: boolean;
      status: 'success';
    }
  | { data: null; error: string; refresh: () => void; status: 'error' }
  | { data: null; error: null; refresh: () => void; status: 'loading' };

type PlayoutsScreenState =
  | { data: PlayoutsScreenData; error: null; itemsLoading: boolean; status: 'success' }
  | { data: null; error: string; status: 'error' }
  | { data: null; error: null; status: 'loading' };

export function getPlayouts(): Promise<PlayoutsPage> {
  return request<PlayoutsPage>('/api/playouts');
}

export function getPlayout(playoutId: number): Promise<PlayoutDetail> {
  return request<PlayoutDetail>(`/api/playouts/${playoutId}`);
}

export function getPlayoutItems(playoutId: number, showFiller = false): Promise<PlayoutItemsPage> {
  return request<PlayoutItemsPage>(`/api/playouts/${playoutId}/items${showFiller ? '?showFiller=true' : ''}`);
}

export function getPlayoutWarningsCount(): Promise<number> {
  return request<number>('/api/playouts/warnings/count');
}

export function getPlayoutChannelStates(): Promise<PlayoutChannelState[]> {
  return request<PlayoutChannelState[]>('/api/channels/state');
}

export function resetAllPlayouts(): Promise<void> {
  return request<void>('/api/playouts/reset-all', { method: 'POST' });
}

export function createPlayout(body: CreatePlayoutRequest): Promise<PlayoutDetail> {
  return request<PlayoutDetail>('/api/playouts', {
    body,
    method: 'POST'
  });
}

export function updatePlayoutDetails(playoutId: number, body: UpdatePlayoutDetailsRequest): Promise<PlayoutDetail> {
  return request<PlayoutDetail>(`/api/playouts/${playoutId}`, {
    body,
    method: 'PUT'
  });
}

export function usePlayoutsScreenQuery(pollMs = 30000): PlayoutsScreenQueryState {
  const [state, setState] = useState<PlayoutsScreenState>({
    data: null,
    error: null,
    status: 'loading'
  });
  const [showFiller, setShowFillerState] = useState(false);
  const activeRef = useRef(true);
  const selectedPlayoutIdRef = useRef<number | null>(null);
  const showFillerRef = useRef(false);
  // Snapshot of the last-known base fields (everything but the selected playout's
  // detail/items), kept in sync whenever load()/loadChannelStates() succeed. Reading
  // this lets setActivePlayout/setShowFiller kick off their fetch without doing the
  // fetch from inside a setState updater (impure; StrictMode double-invokes updaters).
  const baseRef = useRef<PlayoutsScreenBase>({
    channelStates: [],
    playouts: [],
    selectedPlayoutId: null,
    totalCount: 0,
    warningsCount: 0
  });

  useEffect(() => {
    activeRef.current = true;

    return () => {
      activeRef.current = false;
    };
  }, []);

  const loadSelectedPlayout = useCallback((playoutId: number, base: PlayoutsScreenBase) => {
    baseRef.current = base;

    Promise.all([getPlayout(playoutId), getPlayoutItems(playoutId, showFillerRef.current)])
      .then(([playout, itemsPage]) => {
        if (!activeRef.current || selectedPlayoutIdRef.current !== playoutId) {
          return;
        }

        setState((current) => {
          // Merge onto whatever channel state the background poll may have landed
          // while this request was in flight, rather than clobbering it with the
          // snapshot captured when the request started.
          const channelStates = current.status === 'success' ? current.data.channelStates : base.channelStates;

          return {
            data: {
              ...base,
              channelStates,
              items: itemsPage.page ?? [],
              playout,
              selectedPlayoutId: playoutId
            },
            error: null,
            itemsLoading: false,
            status: 'success'
          };
        });
      })
      .catch((error: unknown) => {
        if (activeRef.current && selectedPlayoutIdRef.current === playoutId) {
          setState({ data: null, error: messageFromPlayoutError(error), status: 'error' });
        }
      });
  }, []);

  const load = useCallback(() => {
    Promise.all([getPlayouts(), getPlayoutWarningsCount(), getPlayoutChannelStates()])
      .then(([playoutsPage, warningsCount, channelStates]) => {
        if (!activeRef.current) {
          return;
        }

        const playouts = playoutsPage.page ?? [];
        const selectedPlayoutId = selectedPlayoutIdRef.current && playouts.some((playout) => playout.id === selectedPlayoutIdRef.current)
          ? selectedPlayoutIdRef.current
          : playouts[0]?.id ?? null;
        selectedPlayoutIdRef.current = selectedPlayoutId;

        const base: PlayoutsScreenBase = {
          channelStates,
          playouts,
          selectedPlayoutId,
          totalCount: playoutsPage.totalCount,
          warningsCount
        };
        baseRef.current = base;

        if (selectedPlayoutId == null) {
          setState({
            data: {
              ...base,
              items: [],
              playout: null
            },
            error: null,
            itemsLoading: false,
            status: 'success'
          });
          return;
        }

        loadSelectedPlayout(selectedPlayoutId, base);
      })
      .catch((error: unknown) => {
        if (activeRef.current) {
          setState({ data: null, error: messageFromPlayoutError(error), status: 'error' });
        }
      });
  }, [loadSelectedPlayout]);

  const loadChannelStates = useCallback(() => {
    getPlayoutChannelStates()
      .then((channelStates) => {
        if (!activeRef.current) {
          return;
        }

        baseRef.current = { ...baseRef.current, channelStates };

        setState((current) => {
          if (current.status !== 'success') {
            return current;
          }

          return {
            data: { ...current.data, channelStates },
            error: null,
            itemsLoading: current.itemsLoading,
            status: 'success'
          };
        });
      })
      .catch(() => {
        // Keep the monitor visible on background polling failures.
      });
  }, []);

  useEffect(() => {
    load();

    const intervalId = window.setInterval(loadChannelStates, pollMs);

    return () => {
      window.clearInterval(intervalId);
    };
  }, [load, loadChannelStates, pollMs]);

  const refresh = useCallback(() => {
    setState({ data: null, error: null, status: 'loading' });
    load();
  }, [load]);

  const setActivePlayout = useCallback((playoutId: number) => {
    selectedPlayoutIdRef.current = playoutId;

    setState((current) => {
      if (current.status !== 'success') {
        return current;
      }

      return {
        data: {
          ...current.data,
          items: [],
          playout: null,
          selectedPlayoutId: playoutId
        },
        error: null,
        itemsLoading: true,
        status: 'success'
      };
    });

    const base: PlayoutsScreenBase = { ...baseRef.current, selectedPlayoutId: playoutId };
    loadSelectedPlayout(playoutId, base);
  }, [loadSelectedPlayout]);

  const setShowFiller = useCallback((next: boolean) => {
    showFillerRef.current = next;
    setShowFillerState(next);

    const playoutId = selectedPlayoutIdRef.current;

    if (playoutId == null) {
      return;
    }

    setState((current) => {
      if (current.status !== 'success') {
        return current;
      }

      return { ...current, itemsLoading: true };
    });

    getPlayoutItems(playoutId, next)
      .then((itemsPage) => {
        if (!activeRef.current || selectedPlayoutIdRef.current !== playoutId) {
          return;
        }

        setState((current) => {
          if (current.status !== 'success') {
            return current;
          }

          return {
            data: { ...current.data, items: itemsPage.page ?? [] },
            error: null,
            itemsLoading: false,
            status: 'success'
          };
        });
      })
      .catch((error: unknown) => {
        if (!activeRef.current || selectedPlayoutIdRef.current !== playoutId) {
          return;
        }

        setState({ data: null, error: messageFromPlayoutError(error), status: 'error' });
      });
  }, []);

  if (state.status === 'success') {
    return {
      data: state.data,
      error: null,
      itemsLoading: state.itemsLoading,
      refresh,
      setActivePlayout,
      setShowFiller,
      showFiller,
      status: 'success'
    };
  }

  if (state.status === 'error') {
    return { data: null, error: state.error, refresh, status: 'error' };
  }

  return { data: null, error: null, refresh, status: 'loading' };
}

function messageFromPlayoutError(error: unknown, fallback = 'Unable to load playouts'): string {
  if (error instanceof ApiError) {
    return error.detail ?? error.message;
  }

  if (error instanceof Error) {
    return error.message;
  }

  return fallback;
}