import type {
  IMediaElementEventMap,
  IMediaSourceEventMap,
  ISourceBufferEventMap,
} from "../../../compat/browser_compatibility_types";
import { insertInto, keepRangeIntersection } from "../../../utils/ranges";
import type { CancellationSignal } from "../../../utils/task_canceller";
import type { DummyMediaElement } from "./html5";
import type { DummyMediaSource, DummySourceBuffer } from "./mse";

interface IDummySourceBufferEventObject {
  resolve: () => void;
  reject: (e: unknown) => void;
  obj: DummySourceBuffer;
  evtName: keyof ISourceBufferEventMap;
  cancelSignal: CancellationSignal | null;
}
interface IDummyMediaSourceEventObject {
  resolve: () => void;
  reject: (e: unknown) => void;
  obj: DummyMediaSource;
  evtName: keyof IMediaSourceEventMap;
  cancelSignal: CancellationSignal | null;
}

export class EventScheduler {
  private _scheduled: Array<IDummySourceBufferEventObject | IDummyMediaSourceEventObject>;
  constructor() {
    this._scheduled = [];
  }

  public schedule(
    obj: DummyMediaElement,
    evtName: keyof IMediaElementEventMap,
    cancelSignal: CancellationSignal | null | undefined,
  ): Promise<void>;
  public schedule(
    obj: DummyMediaSource,
    evtName: keyof IMediaSourceEventMap,
    cancelSignal: CancellationSignal | null | undefined,
  ): Promise<void>;
  public schedule(
    obj: DummySourceBuffer,
    evtName: keyof ISourceBufferEventMap,
    cancelSignal: CancellationSignal | null | undefined,
  ): Promise<void>;
  public schedule(
    obj: DummyMediaElement | DummyMediaSource | DummySourceBuffer,
    evtName:
      | keyof IMediaElementEventMap
      | keyof IMediaSourceEventMap
      | keyof ISourceBufferEventMap,
    cancelSignal: CancellationSignal | null | undefined,
  ): Promise<void> {
    return new Promise<void>((res, rej) => {
      /* eslint-disable */
      this._scheduled.push({
        resolve: res,
        reject: rej,
        obj: obj as any,
        evtName: evtName as any,
        cancelSignal: cancelSignal ?? null,
      });
      /* eslint-enable */
      if (this._scheduled.length === 1) {
        this._start();
      }
    });
  }

  private _start() {
    const elt = this._scheduled[0];
    if (elt === undefined) {
      return;
    }
    /* eslint-disable */
    let timeout: ReturnType<typeof setTimeout> | null;
    timeout = setTimeout(() => {
      const { evtName, obj } = elt;
      timeout = null;
      const event = new Event(evtName);
      const handlerFnName = `on${evtName}` as any;
      if ((obj as any)[handlerFnName] !== null) {
        try {
          (obj as any)[handlerFnName](event);
        } catch (e) {
          // nothing
        }
      }
      timeout = setTimeout(() => {
        timeout = null;
        (obj as any).trigger(evtName as any, event);
        const index = this._scheduled.indexOf(elt);
        if (index >= 0) {
          this._scheduled.splice(index, 1);
        }
        elt.resolve();
        this._start();
      }, 0);
    }, 0);
    /* eslint-enable */
    elt.cancelSignal?.register((err) => {
      if (timeout !== null) {
        clearTimeout(timeout);
        timeout = null;
      }
      const index = this._scheduled.indexOf(elt);
      if (index >= 0) {
        this._scheduled.splice(index, 1);
      }
      elt.reject(err);
      this._start();
    });
  }
}

/**
 * Simulate TimeRanges as returned by SourceBuffer.prototype.buffered.
 * Add an "insert" and "remove" methods to manually update it.
 * @class TimeRangesWithMetadata
 */
export default class TimeRangesWithMetadata<T> implements TimeRanges {
  public length: number;

  private _rangesWithMetadata: Array<{
    start: number;
    end: number;
    info: T;
  }>;

  private _ranges: Array<{
    start: number;
    end: number;
  }>;

  constructor() {
    this._ranges = [];
    this._rangesWithMetadata = [];
    this.length = 0;
  }

  insert(start: number, end: number, info: T): void {
    insertInto(this._ranges, { start, end });
    this.length = this._ranges.length;
    insertToMetadataRanges(this._rangesWithMetadata, { start, end, info });
  }

  getMetadataFor(time: number): T | null {
    for (const element of this._rangesWithMetadata) {
      if (element.start <= time && element.end > time) {
        return element.info;
      }
    }
    return null;
  }

  getRangeFor(time: number): { start: number; end: number } | null {
    for (const element of this._rangesWithMetadata) {
      if (element.start <= time && element.end > time) {
        return { start: element.start, end: element.end };
      }
    }
    return null;
  }

  remove(start: number, end: number): void {
    const rangesToIntersect: Array<{ start: number; end: number }> = [];
    if (start > 0) {
      rangesToIntersect.push({ start: 0, end: start });
    }
    if (end < Infinity) {
      rangesToIntersect.push({ start: end, end: Infinity });
    }
    this._ranges = keepRangeIntersection(this._ranges, rangesToIntersect);
    this.length = this._ranges.length;

    for (let i = 0; i < this._rangesWithMetadata.length; i++) {
      const element = this._rangesWithMetadata[i];
      if (element.end > start) {
        if (element.start >= end) {
          // Our element is after:
          //
          // Case 1:
          // element  :      |=======|
          // removing : |====|
          //
          // Case 2:
          // element  :         |=======|
          // removing : |====|
          return;
        }
        if (element.end <= end) {
          if (element.start >= start) {
            // Our element is totally included:
            //
            // Case 1:
            // element  :  |=======|
            // removing :  |=======|
            //
            // Case 2:
            // element  :  |=======|
            // removing :  |=========|
            //
            // Case 3:
            // element  :  |=======|
            // removing : |=========|
            //
            // Case 4:
            // element  :  |=======|
            // removing : |========|
            this._rangesWithMetadata.splice(i, 1);
            i--;
          } else {
            // Our element starts before:
            //
            // Case 1:
            // element  :  |=======|
            // removing :    |=====|
            // result   :  |=|
            //
            // Case 2:
            // element  :  |=======|
            // removing :      |=====|
            // result   :  |===|
            element.end = start;
          }
        } else if (element.start >= start) {
          // Our element just ends after
          //
          // Case 1:
          // element  :   |==========|
          // removing : |=======|
          // result   :         |====|
          //
          // Case 2:
          // element  : |============|
          // removing : |=========|
          // result   :           |==|
          element.start = end;
          return;
        } else {
          // Case 1:
          // element  : |=============|
          // removing :     |====|
          // result   : |===|    |====|
          const oldEnd = element.end;
          element.end = start;
          const nextElement = {
            start: end,
            end: oldEnd,
            info: element.info,
          };
          this._rangesWithMetadata.splice(i + 1, 0, nextElement);
          return;
        }
      }
    }
  }

  start(index: number): number {
    if (index >= this._ranges.length) {
      throw new Error("INDEX_SIZE_ERROR");
    }
    return this._ranges[index].start;
  }

  end(index: number): number {
    if (index >= this._ranges.length) {
      throw new Error("INDEX_SIZE_ERROR");
    }
    return this._ranges[index].end;
  }
}

function insertToMetadataRanges<T>(
  ranges: Array<{ start: number; end: number; info: T }>,
  element: { start: number; end: number; info: T },
): void {
  const { start, end } = element;
  if (start >= end) {
    return;
  }

  // begin by the end as in most use cases this will be faster
  for (let i = ranges.length - 1; i >= 0; i--) {
    const elementI = ranges[i];
    if (elementI.start <= start) {
      if (elementI.end <= start) {
        // our element is after, push it after this one
        //
        // Case 1:
        //   prevElement : |------|
        //   element     :        |======|
        //   ===>        : |------|======|
        //
        // Case 2:
        //   prevElement : |------|
        //   element     :          |======|
        //   ===>        : |------| |======|
        ranges.splice(i + 1, 0, { ...element });

        i += 2; // Go to element immediately after element
        while (i < ranges.length && ranges[i].start < element.end) {
          if (ranges[i].end > element.end) {
            ranges[i].start = element.end;
            return;
          }
          // The next element was completely contained in element.
          // Remove it.
          //
          // Case 1:
          //   prevElement : |------|
          //   element     :        |======|
          //   nextElement :          |---|
          //   ===>        : |------|======|
          //
          // Case 2:
          //   prevElement  : |------|
          //   element   :        |======|
          //   nextElement  :          |----|
          //   ===>         : |------|======|
          ranges.splice(i, 1);
        }
        return;
      } else {
        if (elementI.start === start) {
          if (elementI.end <= end) {
            // In those cases, replace
            //
            // Case 1:
            //  prevElement  : |-------|
            //  element   : |=======|
            //  ===>         : |=======|
            //
            // Case 2:
            //  prevElement  : |-------|
            //  element   : |==========|
            //  ===>         : |==========|
            ranges.splice(i, 1, element);
            i += 1; // Go to element immediately after element
            while (i < ranges.length && ranges[i].start < element.end) {
              if (ranges[i].end > element.end) {
                // The next element ends after element.
                // Mutate the next element.
                //
                // Case 1:
                //   element   : |======|
                //   nextElement  :      |----|
                //   ===>         : |======|--|
                ranges[i].start = element.end;
                return;
              }
              // The next element was completely contained in element.
              // Remove it.
              //
              // Case 1:
              //   element   : |======|
              //   nextElement  :   |---|
              //   ===>         : |======|
              //
              // Case 2:
              //   element   : |======|
              //   nextElement  :   |----|
              //   ===>         : |======|
              ranges.splice(i, 1);
            }
            return;
          } else {
            // The previous element starts at the same time and finishes
            // after the new element.
            // Update the start of the previous element and put the new
            // element before.
            //
            // Case 1:
            //  prevElement  : |------------|
            //  element   : |==========|
            //  ===>         : |==========|-|
            ranges.splice(i, 0, element);
            elementI.start = element.end;
            return;
          }
        } else {
          if (elementI.end <= element.end) {
            // our element has a "complex" relation with this one,
            // update the old one end and add this one after it.
            //
            // Case 1:
            //  prevElement  : |-------|
            //  element   :    |======|
            //  ===>         : |--|======|
            //
            // Case 2:
            //  prevElement  : |-------|
            //  element   :    |====|
            //  ===>         : |--|====|
            ranges.splice(i + 1, 0, element);
            elementI.end = element.start;
            i += 2; // Go to element immediately after element
            while (i < ranges.length && ranges[i].start < element.end) {
              if (ranges[i].end > element.end) {
                // The next element ends after element.
                // Mutate the next element.
                //
                // Case 1:
                //   element   : |======|
                //   nextElement  :      |----|
                //   ===>         : |======|--|
                ranges[i].start = element.end;
                return;
              }
              // The next element was completely contained in element.
              // Remove it.
              //
              // Case 1:
              //   element   : |======|
              //   nextElement  :   |---|
              //   ===>         : |======|
              //
              // Case 2:
              //   element   : |======|
              //   nextElement  :   |----|
              //   ===>         : |======|
              ranges.splice(i, 1);
            }
            return;
          } else {
            // The previous element completely recovers the new element.
            // Split the previous element into two elements, before and after
            // the new element.
            //
            // Case 1:
            //  prevElement  : |---------|
            //  element   :    |====|
            //  ===>         : |--|====|-|
            const nextElement = {
              start: element.end,
              end: elementI.end,
              info: elementI.info,
            };
            elementI.end = element.start;
            ranges.splice(i + 1, 0, element);
            ranges.splice(i + 2, 0, nextElement);
            return;
          }
        }
      }
    }
  }

  // if we got here, we are at the first element
  // check bounds of the previous first element
  const firstElement = ranges[0];
  if (firstElement === undefined) {
    // we do not have any element yet
    ranges.push(element);
    return;
  }

  if (firstElement.start >= end) {
    // our element is before, put it before
    //
    // Case 1:
    //  firstElement :      |----|
    //  element   : |====|
    //  ===>         : |====|----|
    //
    // Case 2:
    //  firstElement :        |----|
    //  element   : |====|
    //  ===>         : |====| |----|
    ranges.splice(0, 0, element);
  } else if (firstElement.end <= end) {
    // Our segment is bigger, replace the first
    //
    // Case 1:
    //  firstElement :   |---|
    //  element   : |=======|
    //  ===>         : |=======|
    //
    // Case 2:
    //  firstElement :   |-----|
    //  element   : |=======|
    //  ===>         : |=======|
    ranges.splice(0, 1, element);
    while (ranges.length > 1 && ranges[1].start < element.end) {
      if (ranges[1].end > element.end) {
        // The next segment ends after element.
        // Mutate the next segment.
        //
        // Case 1:
        //   element   : |======|
        //   nextElement  :      |----|
        //   ===>         : |======|--|
        ranges[1].start = element.end;
        return;
      }
      // The next segment was completely contained in element.
      // Remove it.
      //
      // Case 1:
      //   element   : |======|
      //   nextElement  :   |---|
      //   ===>         : |======|
      //
      // Case 2:
      //   element   : |======|
      //   nextElement  :   |----|
      //   ===>         : |======|
      ranges.splice(1, 1);
    }
    return;
  } else {
    // our segment has a "complex" relation with the first one,
    // update the old one start and add this one before it.
    //
    // Case 1:
    //  firstElement :    |------|
    //  element   : |======|
    //  ===>         : |======|--|
    firstElement.start = end;
    ranges.splice(0, 0, element);
    return;
  }
}