chunked range

range.ts

namespace $ {
	export class $gd_kit_range<Item> extends $mol_object {
		@ $mol_mem
		protected server_count(next?: number | null): number {
			throw new Error('implement')
		}

		@ $mol_mem_key
		protected server_chunk(offset: number, next?: null): readonly Item[] {
			throw new Error('implement')
		}

		limit() {
			return 100
		}

		@ $mol_mem
		protected temp(next?: null | readonly string[]) {
			return next
		}

		@ $mol_action
		temp_push(...ids: readonly string[]) {
			this.temp([ ...this.temp() ?? [], ...ids ])
			this.temp_cut()
		}

		temp_chunk_min() {
			return 1
		}

		temp_cut() {
			const temp = this.temp()
			if (! temp) return

			const limit = this.limit()
			const delete_chunks = Math.ceil(temp.length / limit) - this.temp_chunk_min()
			if (delete_chunks <= 0) return

			const delete_count = delete_chunks * limit
			this.server_count(this.server_count() + delete_count)
			this.temp(temp.slice(0, delete_count))
		}

		protected server_item(index: number, reset?: null) {
			const limit = this.limit()

			const offset = Math.floor(index / limit) * limit
			const chunk_index = index % limit

			const chunk = this.server_chunk(offset, reset)
			const id = chunk[chunk_index]

			return id
		}

		protected item(index: number, reset?: null) {
			const count = this.server_count()
			const temp = this.temp()
			if (index < count) return this.server_item(index, reset)
			return temp?.[index - count]!
		}

		protected count() {
			return this.server_count() + ( this.temp()?.length ?? 0)
		}

		@ $mol_mem
		range() {
			return this.$.$mol_range2(index => this.item(index), () => this.count())
		}
	}
}