import { Course, Bar } from 'tja-parser';

export namespace Factor {
    // 노트 추출 및 정렬 (시간순)
    export function getAllNotes(course: Course) {
        const notes: { type: number, time: number }[] = [];
        for (const group of course.noteGroups) {
            if (group instanceof Bar) {
                // 파서 구조에 따라 노트 추출 방식 조정 필요
                notes.push(...group.getNotes().map((note) => {
                    return {
                        //@ts-expect-error
                        type: note.type,
                        time: note.getTimingMS()
                    }
                }));
            }
        }
        return notes.sort((a, b) => a.time - b.time).filter(n => [1, 2, 3, 4].includes(n.type));
    }

    export function getAverageDensity(notes: { time: number }[]): number {
        if (notes.length < 2) return 0;
        const duration = (notes[notes.length - 1].time - notes[0].time) / 1000;
        return duration > 0 ? notes.length / duration : 0;
    }

    export function getPeakDensity(notes: { time: number }[]): number {
        if (notes.length === 0) return 0;
        let maxPeak = 0;
        const windowSize = 1000;
        for (let i = 0; i < notes.length; i++) {
            let count = 0;
            const startTime = notes[i].time;
            for (let j = i; j < notes.length && notes[j].time < startTime + windowSize; j++) {
                count++;
            }
            maxPeak = Math.max(maxPeak, count);
        }
        return maxPeak;
    }

    export function getMaxCombo(notes: any[]): number {
        return notes.length;
    }
}

export function factorize(course: Course) {
    const notes = Factor.getAllNotes(course);
    return {
        average_density: Factor.getAverageDensity(notes),
        peak_density: Factor.getPeakDensity(notes),
        max_combo: Factor.getMaxCombo(notes)
    };
}