import type { ApplogForInsertOptionalAgent, ApplogValue, EntityID } from '../applog/datom-types.ts'

/**
 * Generic ObjectBuilder for type-safe entity creation and updates.
 *
 * Provides a fluent API to build a set of applogs for an entity.
 * Modeled after the note3 builder pattern.
 *
 * Usage:
 * ```ts
 * ObjectBuilder.create({ name: 'foo' })
 *   .update({ type: 'bar' })
 *   .build(thread)
 * ```
 */
export class ObjectBuilder<
	TARGET extends Record<string, ApplogValue> = Record<string, ApplogValue>,
> {
	constructor(
		private _data: Partial<TARGET>,
		public en: EntityID | null = null,
		private _atPrefix: string | null = null,
		private _atOverrides: Partial<Record<keyof TARGET, string>> = {},
	) {}

	/**
	 * Create a new builder with initial data.
	 */
	static create<TARGET extends Record<string, ApplogValue>>(
		init: Partial<TARGET> = {},
		en?: EntityID,
		atPrefix?: string,
		atOverrides?: Partial<Record<keyof TARGET, string>>,
	): ObjectBuilder<TARGET> {
		return new ObjectBuilder<TARGET>(init, en, atPrefix, atOverrides)
	}

	/**
	 * Update the data being built.
	 */
	update(updateObj: Partial<TARGET>): this {
		Object.assign(this._data, updateObj)
		return this
	}

	/**
	 * Build the applogs for this entity, optionally resolving against a thread.
	 */
	build(thread?: {
		insert(applogs: ApplogForInsertOptionalAgent[]): ApplogForInsertOptionalAgent[]
	}): ApplogForInsertOptionalAgent[] {
		const atPrefix = this._atPrefix
		const applogs: ApplogForInsertOptionalAgent[] = []

		for (const [key, value] of Object.entries(this._data) as [keyof TARGET, ApplogValue][]) {
			if (value === undefined) continue
			const atOverride = this._atOverrides[key]
			const at = atOverride ?? (atPrefix ? `${atPrefix}/${String(key)}` : String(key))
			applogs.push({ en: this.en!, at, vl: value })
		}

		return applogs
	}

	/**
	 * Get the raw data being built.
	 */
	get data(): Partial<TARGET> {
		return { ...this._data }
	}
}