const PRETALX_URL = `https://pretalx.lebib.org/`
const EVENT_ID = `camp-interhack-2026-2025`
const TALKS_EXPIRATION = 60*60*1000;
const API_ROOT = new URL("api/", PRETALX_URL);

// Database management

let cached_talks = null;

export async function getFreshTalks(){
    if(!cached_talks || (Date.now() - cached_talks.updatedAt.getTime()) > TALKS_EXPIRATION){
        let talk_list = []
        
        for await(let talk_json of requestAllTalks()){
            if(talk_json.state != "confirmed"){
                continue
            }
            let talk = new Talk(talk_json);
            talk_list.push(talk)
        }
        
        talk_list.sort((a,b) => a.startTime.getTime() - b.startTime.getTime())
        
        // {
        //     let mock_i = 2
        //     talk_list[mock_i].slot.start = new Date(Date.now() - 120*1000).toJSON()
        //     talk_list[mock_i].slot.end = (new Date(Date.now() + 3600000 + ( Math.random()*10000))).toJSON()
        //     console.log("mock event", talk_list[mock_i])
        // }

        let talks_by_room_id = {}
        for(let talk of talk_list) {
            if(!talks_by_room_id[talk.slot.room_id]){
                talks_by_room_id[talk.slot.room_id] = []
            }
            talks_by_room_id[talk.slot.room_id].push(talk)
        }

        cached_talks = {
            updatedAt: new Date(),
            talks: talk_list,
            talks_by_room: talks_by_room_id
        }
    }

    return cached_talks
}

export async function getUpcomingTalksForRoom(room_id){
    let db = await getFreshTalks()
    return (db.talks_by_room[room_id] || []).filter(it => it.endTime.getTime() > Date.now())
}

class Talk {
    constructor(srcObj){
        Object.assign(this, srcObj)
    }
    
    get startTime(){
        return new Date(this.slot.start)
    }
    
    get endTime(){
        return new Date(this.slot.end)
    }

    get displayUrl(){
        return new URL(`${encodeURIComponent(EVENT_ID)}/talk/${encodeURIComponent(this.code)}`, PRETALX_URL).toString()
    }

    get isActive(){
        return this.startTime.getTime() <= Date.now() && this.endTime.getTime() >= Date.now()
    }
}

// Lower level tools

const requestAllRooms = makePaginatedGenerator(new URL(`events/${encodeURIComponent(EVENT_ID)}/rooms/`, API_ROOT))
const requestAllTalks = makePaginatedGenerator(new URL(`events/${encodeURIComponent(EVENT_ID)}/talks/`, API_ROOT))

function makePaginatedGenerator(baseUrl){
    return async function*(){
        let buffer = []
        let next_url = baseUrl
        
        while(buffer.length > 0 || next_url != null){
            let item = buffer.shift()
            if(item){
                yield item
            } else {
                let res = await fetch(next_url)
                if(!res.ok){
                    throw new Error(`Server responded with error ${res.status} ${res.statusText}`)
                }
                let response = await res.json()
                next_url = response.next
                buffer.push(...response.results)
            }
        }
    }
}