import { format } from 'date-fns'

import _ from 'lodash'
import { useEffect, useRef, useState } from 'preact/hooks'
import { prettyCourseName, WEEK_DAYS } from '../../utils.jsx'

export const Course = ({ events, selection, setSelection, hideOtherCourses }) => {
    const selectionSet = new Set(selection)

    const visibleEvents = !hideOtherCourses ? events : events.filter(e => selectionSet.has(e.id))

    const eventsByCourse = _.groupBy(_.sortBy(visibleEvents, 'id'), 'id')

    const profsPerCourse = _.mapValues(eventsByCourse, events =>
        _.uniq(events.flatMap(event => event.docenti))
    )

    const [currentlyHovered, setCurrentlyHovered] = useState(null)
    const element = useRef()

    useEffect(() => {
        if (element.current) {
            const l = e => {
                const isMobile = window.matchMedia('(pointer: coarse)').matches

                const $course = e.target.closest('.course')
                if ($course && !isMobile) {
                    setCurrentlyHovered($course.dataset.courseId)
                } else {
                    setCurrentlyHovered(null)
                }
            }

            element.current.addEventListener('mousemove', l)
            element.current.addEventListener('mouseleave', l)

            return () => {
                element.current.removeEventListener('mousemove', l)
                element.current.removeEventListener('mouseleave', l)
            }
        }
    }, [element.current])

    return (
        <div class="course-view" ref={element}>
            <div class="wrap-container">
                {Object.entries(eventsByCourse).map(([id, courseEvents]) => (
                    <div
                        class={
                            'course' +
                            (currentlyHovered === id ? ' highlight' : '') +
                            (selectionSet.has(id) ? ' selected' : '')
                        }
                        data-course-id={id}
                        onClick={() => {
                            if (!selectionSet.has(id)) setSelection([...selection, id])
                            else setSelection(selection.filter(selId => selId !== id))
                        }}
                    >
                        <div class="title">{prettyCourseName(courseEvents[0].name)}</div>
                        <div class="docenti">{profsPerCourse[id].join(', ')}</div>
                        <div class="events">
                            {courseEvents.map(course => (
                                <div>
                                    {WEEK_DAYS[course.start.getDay()]}{' '}
                                    {format(course.start, 'H:mm')}&ndash;
                                    {format(course.end, 'H:mm')} {course.aule.join(', ')}
                                </div>
                            ))}
                        </div>
                    </div>
                ))}
            </div>
        </div>
    )
}