/*
    This file is part of jellything (https://codeberg.org/metamuffin/jellything)
    which is licensed under the GNU Affero General Public License (version 3); see /COPYING.
    Copyright (C) 2023 metamuffin <metamuffin.org>
*/
import { OVar, e } from "../jshelper/mod.ts";

export interface Range { start: number, end: number }
export interface JhlsMetadata {
    tracks: JhlsTrack[],
    duration: number,
}
export interface JhlsTrack {
    info: SourceTrack,
    segments: Range[],
}
export interface SourceTrack {
    kind: SourceTrackKind,
    name: string,
    codec: string,
    language: string,
}
export interface SourceTrackKind {
    video?: {
        width: number,
        height: number,
        fps: number,
    },
    audio?: {
        channels: number,
        sample_rate: number,
        bit_depth: number,
    },
    subtitles?: boolean,
}

const TARGET_BUFFER_DURATION = 15
const MIN_BUFFER_DURATION = 1

document.addEventListener("DOMContentLoaded", () => {
    if (document.body.classList.contains("player")) {
        if (!globalThis.MediaSource) return alert("Media Source Extension API required")
        const node_id = globalThis.location.pathname.split("/")[2];
        const main = document.getElementById("main")!;
        document.getElementsByTagName("footer")[0].remove()
        initialize_player(main, node_id)
    }
})

function initialize_player(el: HTMLElement, node_id: string) {
    el.innerHTML = "" // clear the body

    const player = new Player(node_id)

    const toggle_playing = () => player.playing.value ? player.pause() : player.play()
    const pri_map = (v: number) => (v / player.duration.value * 100) + "%"

    let pri_current: HTMLElement;
    let pri: HTMLElement;
    const controls = e("div", { class: "jsp-controls" },
        player.playing.map(playing => e("button", playing ? "||" : "|>", { onclick: toggle_playing })),
        e("p", { class: "jsp-status" },
            player.position.map(v => e("span", display_time(v))), e("br"),
            player.position.map(v => e("span", display_time(v - player.duration.value)))
        ),
        pri = e("div", { class: "jsp-pri" },
            pri_current = e("div", { class: "jsp-pri-current" }),
            player.tracks.map(
                tracks => e("div", ...tracks.map((t, i) => t.buffered.map(
                    ranges => e("div", ...ranges.map(
                        r => e("div", {
                            class: ["jsp-pri-buffer", `jsp-pri-buffer-${r.status}`],
                            style: {
                                width: pri_map(r.end - r.start),
                                top: `calc(var(--pribufsize)*${i})`,
                                left: pri_map(r.start)
                            }
                        })
                    ))
                )))
            )
        ),
        e("button", "X", {
            onclick() {
                if (document.fullscreenElement) document.exitFullscreen()
                else document.documentElement.requestFullscreen()
            }
        })
    )

    player.position.onchangeinit(p => pri_current.style.width = pri_map(p))

    const pel = e("div", { class: "jsp" },
        player.video,
        player.buffering_status.map(b => e("div", { class: "jsp-overlay" },
            b ? e("p", { class: "jsp-buffering" }, b) : undefined
        )),
        controls,
    )
    el.append(pel)

    mouse_idle(pel, 1000, idle => {
        controls.style.opacity = idle ? "0" : "1"
        pel.style.cursor = idle ? "none" : "default"
    })

    player.video.addEventListener("click", toggle_playing)
    pri.addEventListener("mousedown", ev => {
        const r = pri.getBoundingClientRect()
        const p = (ev.clientX - r.left) / (r.right - r.left)
        player.seek(p * player.duration.value)
    })
    document.body.addEventListener("keydown", k => {
        if (k.code == "Period") player.pause(), player.frame_forward()
        if (k.code == "Space") toggle_playing()
        else if (k.code == "ArrowLeft") player.seek(player.position.value - 5)
        else if (k.code == "ArrowRight") player.seek(player.position.value + 5)
        else if (k.code == "ArrowUp") player.seek(player.position.value - 60)
        else if (k.code == "ArrowDown") player.seek(player.position.value + 60)
        else return;
        k.preventDefault()
    })

}

function mouse_idle(e: HTMLElement, timeout: number, cb: (b: boolean) => unknown) {
    let ct: number;
    let idle = false
    e.onmouseleave = () => { clearTimeout(ct) }
    e.onmousemove = () => {
        clearTimeout(ct)
        if (idle) {
            idle = false
            cb(idle)
        }
        ct = setTimeout(() => {
            idle = true
            cb(idle)
        }, timeout)
    }
}
function display_time(t: number): string {
    if (t < 0) return "-" + display_time(-t)
    let h = 0, m = 0, s = 0;
    while (t > 3600) t -= 3600, h++;
    while (t > 60) t -= 60, m++;
    while (t > 1) t -= 1, s++;
    return (h ? h + "h" : "") + (m ? m + "m" : "") + (s ? s + "s" : "")
}

interface BufferRange extends Range { status: "buffered" | "loading" | "queued" }
class Player {
    public video = e("video")
    private media_source = new MediaSource();
    public tracks = new OVar<PlayerTrack[]>([]);

    public position = new OVar(0)
    public duration = new OVar(1)
    public playing = new OVar(false)
    public canplay = new OVar(false)
    public buffering_status = new OVar<string | undefined>(undefined)
    public error = new OVar<string | undefined>(undefined)

    constructor(private node_id: string) {
        this.video.onloadedmetadata = () => { }
        this.video.ondurationchange = () => { }
        this.video.ontimeupdate = () => {
            this.position.value = this.video.currentTime
            this.update() // TODO maybe not here
        }
        this.video.onplay = () => {
            console.log("play");
            this.buffering_status.value = "Resuming playback...";
        }
        this.video.onwaiting = () => {
            console.log("waiting");
            this.buffering_status.value = "Buffering...";
            this.canplay.value = false;
        }
        this.video.onplaying = () => {
            console.log("playing");
            this.playing.value = true;
            this.buffering_status.value = undefined;
        }
        this.video.onpause = () => {
            console.log("pause");
            this.playing.value = false
        }
        this.video.oncanplay = () => {
            console.log("canplay");
            this.buffering_status.value = undefined
            this.canplay.value = true
        }
        this.video.onseeking = () => {
            console.log("seeking");
            this.buffering_status.value = "Seeking..."
        }
        this.video.onseeked = () => {
            console.log("seeked");
            this.buffering_status.value = undefined
        }
        this.fetch_meta()
    }

    async fetch_meta() {
        this.buffering_status.value = "Loading JHLS metadata..."
        const res = await fetch(`/n/${encodeURIComponent(this.node_id)}/stream?format=jhls`)
        if (!res.ok) return this.error.value = "Cannot download JHLS metadata"
        const metadata = await res.json() as JhlsMetadata
        this.buffering_status.value = undefined

        this.duration.value = metadata.duration
        this.video.src = URL.createObjectURL(this.media_source)
        this.media_source.addEventListener("sourceopen", async () => {
            this.tracks.value.push(new PlayerTrack(this.media_source, this.node_id, 0, metadata.tracks[0]))
            this.tracks.value.push(new PlayerTrack(this.media_source, this.node_id, 1, metadata.tracks[1]))
            this.tracks.change()
            this.buffering_status.value = "Fetching initial segments..."
            this.update()
            await this.canplay.wait_for(true)
            this.buffering_status.value = undefined
        })
    }
    async update(newt?: number) {
        await Promise.all(this.tracks.value.map(t => t.update(newt ?? this.video.currentTime)))
    }

    play() {
        this.video.play()
    }
    pause() {
        this.video.pause()
    }
    frame_forward() {
        //@ts-ignore trust me bro
        this.video["seekToNextFrame"]()
    }
    async seek(p: number) {
        this.buffering_status.value = "Buffering at target..."
        await this.update(p)
        this.video.currentTime = p
    }

}

interface AppendRange extends Range { buf: ArrayBuffer, index: number, cb: () => void }
class PlayerTrack {
    private source_buffer: SourceBuffer
    private current_load?: AppendRange
    private loading = new Set<number>()
    public buffered = new OVar<BufferRange[]>([])
    private append_queue: AppendRange[] = []
    constructor(media_source: MediaSource, private node_id: string, private track_index: number, private metadata: JhlsTrack) {
        this.source_buffer = media_source.addSourceBuffer("video/webm")
        this.source_buffer.mode = "segments"
        this.source_buffer.addEventListener("updateend", () => {
            if (this.current_load) {
                this.current_load.cb()
                this.loading.delete(this.current_load.index)
                this.current_load = undefined
            }
            this.update_buf_ranges()
            this.tick_append()
        })
        this.source_buffer.addEventListener("error", e => {
            console.error("sourcebuffer error", e);
        })
    }

    update_buf_ranges() {
        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.metadata.segments[r], status: "loading" })
        }
        this.buffered.value = ranges
    }

    async update(target: number) {
        this.update_buf_ranges() // TODO required?

        const blocking = []
        for (let i = 0; i < this.metadata.segments.length; i++) {
            const seg = this.metadata.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)
        const res = await fetch(`/n/${encodeURIComponent(this.node_id)}/stream?format=hlsseg&tracks=${this.track_index}&index=${index}`)
        if (!res.ok) throw new Error(`segment fail i=${index} t=${this.track_index}`);
        const buf = await res.arrayBuffer()

        await new Promise<void>(cb => {
            this.append_queue.push({ buf, ...this.metadata.segments[index], index, cb })
            this.tick_append()
        })
    }
    tick_append() {
        if (this.source_buffer.updating) return
        if (this.append_queue.length) {
            const seg = this.append_queue[0];
            this.source_buffer.timestampOffset = seg.start
            this.source_buffer.appendBuffer(seg.buf);
            this.append_queue.splice(0, 1)
            this.current_load = seg
        }
    }
}