import { EventEmitter, Injectable } from '@angular/core'

import { SongResult, SongSearch } from '../../../../src-shared/interfaces/search.interface'
import { VersionResult } from '../../../../src-shared/interfaces/songDetails.interface'

@Injectable({
	providedIn: 'root',
})
export class SearchService {

	private resultsChangedEmitter = new EventEmitter<SongResult[]>() // For when any results change
	private newResultsEmitter = new EventEmitter<SongResult[]>()     // For when a new search happens
	private errorStateEmitter = new EventEmitter<boolean>()          // To indicate the search's error state
	private results: SongResult[] = []
	private awaitingResults = false
	private currentQuery: SongSearch
	private _allResultsVisible = true

	async newSearch(query: SongSearch) {
		if (this.awaitingResults) { return }
		this.awaitingResults = true
		this.currentQuery = query
		try {
			this.results = this.trimLastChart(await window.electron.invoke.songSearch(this.currentQuery))
			this.errorStateEmitter.emit(false)
		} catch (err) {
			this.results = []
			console.log(err.message)
			this.errorStateEmitter.emit(true)
		}
		this.awaitingResults = false

		this.newResultsEmitter.emit(this.results)
		this.resultsChangedEmitter.emit(this.results)
	}

	isLoading() {
		return this.awaitingResults
	}

	/**
	 * Event emitted when new search results are returned
	 * or when more results are added to an existing search.
	 * (emitted after `onNewSearch`)
	 */
	onSearchChanged(callback: (results: SongResult[]) => void) {
		this.resultsChangedEmitter.subscribe(callback)
	}

	/**
	 * Event emitted when a new search query is typed in.
	 * (emitted before `onSearchChanged`)
	 */
	onNewSearch(callback: (results: SongResult[]) => void) {
		this.newResultsEmitter.subscribe(callback)
	}

	/**
	 * Event emitted when the error state of the search changes.
	 * (emitted before `onSearchChanged`)
	 */
	onSearchErrorStateUpdate(callback: (isError: boolean) => void) {
		this.errorStateEmitter.subscribe(callback)
	}

	get resultCount() {
		return this.results.length
	}

	async updateScroll() {
		if (!this.awaitingResults && !this._allResultsVisible) {
			this.awaitingResults = true
			this.currentQuery.offset += 50
			this.results.push(...this.trimLastChart(await window.electron.invoke.songSearch(this.currentQuery)))
			this.awaitingResults = false

			this.resultsChangedEmitter.emit(this.results)
		}
	}

	trimLastChart(results: SongResult[]) {
		if (results.length > 50) {
			results.splice(50, 1)
			this._allResultsVisible = false
		} else {
			this._allResultsVisible = true
		}

		return results
	}

	get allResultsVisible() {
		return this._allResultsVisible
	}

	/**
	 * Orders `versionResults` by lastModified date, but prefer the
	 * non-pack version if it's only a few days older.
	 */
	sortChart(versionResults: VersionResult[]) {
		const dates: { [versionID: number]: number } = {}
		versionResults.forEach(version => dates[version.versionID] = new Date(version.lastModified).getTime())
		versionResults.sort((v1, v2) => {
			const diff = dates[v2.versionID] - dates[v1.versionID]
			if (Math.abs(diff) < 6.048e+8 && v1.driveData.inChartPack !== v2.driveData.inChartPack) {
				if (v1.driveData.inChartPack) {
					return 1 // prioritize v2
				} else {
					return -1 // prioritize v1
				}
			} else {
				return diff
			}
		})
	}
}