import { JhlsTrackIndex, SourceTrack } from "../jhls.d.ts";
import { OVar } from "../../jshelper/mod.ts";
import { profile_to_partial_track, track_to_content_type } from "../mediacaps.ts";
import { BufferRange, Player } from "../player.ts";
import { EncodingProfileExt, ProfileSelector } from "../profiles.ts";
import { PlayerTrack, AppendRange, TARGET_BUFFER_DURATION, MIN_BUFFER_DURATION } from "./mod.ts";

export class MSEPlayerTrack extends PlayerTrack {
  public source_buffer!: SourceBuffer;
  private current_load?: AppendRange;
  private loading = new Set<number>();
  private append_queue: AppendRange[] = [];
  public profile_selector: ProfileSelector;
  public profile = new OVar<EncodingProfileExt | undefined>(undefined);
  public index?: JhlsTrackIndex

  constructor(
    private player: Player,
    private node_id: string,
    track_index: number,
    private metadata: SourceTrack,
  ) {
    super(track_index);
    this.profile_selector = new ProfileSelector(player, this, player.downloader.bandwidth);
    this.init()
  }

  async init() {
    this.buffered.value = [{ start: 0, end: this.player.duration.value, status: "loading" }]
    try {
      const res = await fetch(`/n/${encodeURIComponent(this.node_id)}/stream?format=jhlsi&tracks=${this.track_index}`, { headers: { "Accept": "application/json" } });
      if (!res.ok) return this.player.error.value = "Cannot download index.", undefined;
      let index!: JhlsTrackIndex & { error: string; };
      try { index = await res.json(); }
      catch (_) { this.player.set_pers("Error: Failed to fetch node"); }
      if (index.error) return this.player.set_pers("server error: " + index.error), undefined;
      this.index = index
    } catch (e) {
      if (e instanceof TypeError) {
        this.player.set_pers("Cannot download index: Network Error");
      } else throw e;
    }
    this.buffered.value = []

    await this.profile_selector.select_optimal_profile(this.track_index, this.profile);
    const ct = track_to_content_type(this.track_from_profile())!;
    console.log(`track ${this.track_index} source buffer content-type: ${ct}`);
    this.source_buffer = this.player.media_source.addSourceBuffer(ct);
    this.abort.signal.addEventListener("abort", () => {
      console.log(`destroy source buffer for track ${this.track_index}`);
      this.player.media_source.removeSourceBuffer(this.source_buffer);
    });
    this.source_buffer.mode = "segments";
    this.source_buffer.addEventListener("updateend", () => {
      if (this.abort.signal.aborted) return;
      if (this.current_load) {
        this.loading.delete(this.current_load.index);
        const cb = this.current_load.cb;
        this.current_load = undefined;
        cb()
      } else {
        console.warn("updateend but nothing is loading")
      }
      this.update_buf_ranges();
      this.tick_append();
    });
    this.source_buffer.addEventListener("error", e => {
      console.error("sourcebuffer error", e);
    });
    this.source_buffer.addEventListener("abort", e => {
      console.error("sourcebuffer abort", e);
    });

    this.update(this.player.video.currentTime)
  }
  track_from_profile(): SourceTrack {
    if (this.profile.value) return profile_to_partial_track(this.profile.value);
    else return this.metadata;
  }

  update_buf_ranges() {
    if (!this.index) return;
    const ranges: BufferRange[] = [];
    for (let i = 0; i < this.source_buffer.buffered.length; i++) {
      ranges.push({
        start: this.source_buffer.buffered.start(i),
        end: this.source_buffer.buffered.end(i),
        status: "buffered"
      });
    }
    for (const r of this.loading) {
      ranges.push({ ...this.index.segments[r], status: "loading" });
    }
    this.buffered.value = ranges;
  }

  async update(target: number) {
    if (!this.index) return;
    this.update_buf_ranges(); // TODO required?

    const blocking = [];
    for (let i = 0; i < this.index.segments.length; i++) {
      const seg = this.index.segments[i];
      if (seg.end < target) continue;
      if (seg.start >= target + TARGET_BUFFER_DURATION) break;
      if (!this.check_buf_collision(seg.start, seg.end)) continue;
      if (seg.start <= target + MIN_BUFFER_DURATION)
        blocking.push(this.load(i));
      else
        this.load(i);
    }
    await Promise.all(blocking);
  }
  check_buf_collision(start: number, end: number) {
    const EPSILON = 0.01;
    for (const r of this.buffered.value)
      if (r.end - EPSILON > start && r.start < end - EPSILON)
        return false;
    return true;
  }

  async load(index: number) {
    this.loading.add(index);
    await this.profile_selector.select_optimal_profile(this.track_index, this.profile);
    const url = `/n/${encodeURIComponent(this.node_id)}/stream?format=frag&webm=true&tracks=${this.track_index}&index=${index}${this.profile.value ? `&profile=${this.profile.value.id}` : ""}`;
    const buf = await this.player.downloader.download(url);
    await new Promise<void>(cb => {
      if (!this.index) return;
      if (this.abort.signal.aborted) return;
      this.append_queue.push({ buf, ...this.index.segments[index], index, cb });
      this.tick_append();
    });
  }
  tick_append() {
    if (this.source_buffer.updating || this.current_load) return;
    if (this.append_queue.length) {
      const seg = this.append_queue[0];
      this.append_queue.splice(0, 1);
      this.current_load = seg;
      // TODO why is appending so unreliable?! sometimes it does not add it
      this.source_buffer.changeType(track_to_content_type(this.track_from_profile())!);
      // this.source_buffer.timestampOffset = seg.start;
      this.source_buffer.appendBuffer(seg.buf);
    }
  }
}