thebespokepixel/n-selector

/* ───────────╮
 │ n-selector │ Single n-way switch channel (gang)
 ╰────────────┴──────────────────────────────────────────────────────────────── */

/**
 * @private
 */
export class Gang {
    /**
     * Represents a single gang of switch positions.
     * @param  {string[]}  members The gang's named positions
     * @param  {boolean} primaryIndex Is this gang the primary index?
     * @property {number} memberCount Get the number of members in this gang.
     */
    constructor(members, primaryIndex = false) {
        if (members === undefined || !Array.isArray(members)) {
            throw new Error('A selection gang requires an array of members as the first parameter.')
        }

        this.members = members
        this.index = 0
        this.isPrimaryIndex = primaryIndex
    }

    get memberCount() {
        return this.members.length
    }

    get isPrimary() {
        return this.isPrimaryIndex
    }

    selection(position) {
        return this.members[Math.floor(position * this.members.length)]
    }

    position(idx) {
        return this.indexOf(idx) / this.members.length
    }

    indexOfMember(id) {
        const idx = this.members.indexOf(id)
        if (idx < 0) {
            throw new Error(`${id} not found.`)
        }

        return idx
    }

    indexOf(idx) {
        if (idx < 0) {
            idx = 0
        }

        if (idx > this.members.length) {
            idx = this.members.length
        }

        return idx
    }
}
/**
 * Add a gang of members.
 * @private
 * @param {Array}  members   Gang members.
 * @param {Boolean} isPrimary Is the primary gang.
 * @returns {Gang} Gang object.
 */
export function addGang(members, isPrimary) {
    return new Gang(members, isPrimary)
}