import {Component, Input, Output, OnInit, OnDestroy, EventEmitter, OnChanges} from '@angular/core';
import {ActivatedRoute, Router} from '@angular/router';
import config from "@common/config";
import StorageService from "@common/services/storage";
import UtilService from "@common/services/util";

@Component({
    selector: 'pagination',
    templateUrl: './template.html',
    styleUrls: ['./style.less']
})
export default class Pagination implements OnInit, OnDestroy, OnChanges {
    @Input() pageTotal: number;
    @Input() pageNum: any;
    @Input() totalItems: any;
    @Output() pageChange: EventEmitter<any> = new EventEmitter();

    pageCurrent = 1;
    pagesLength = 9;
    pageList = [];
    private paramsSub;
    pageSize = 10;

    constructor(private activatedRoute: ActivatedRoute,
                private storageService: StorageService, private router: Router) {
    }

    ngOnInit(): void {
        this.pageSize = this.storageService.get('pageSize') || config.limit;
        if (this.pageChange.observers.length > 0) {
            this.pageCurrent = this.pageNum;
        } else {
            this.paramsSub = this.activatedRoute.params.subscribe(params => {
                this.pageCurrent = (<any>params).pageNum;
                this.getPageList()
            })
        }
    }

    ngOnDestroy(): void {
        this.paramsSub && this.paramsSub.unsubscribe();
    }

    ngOnChanges(changes: any): void {
        if (changes.pageNum) {
            this.pageCurrent = changes.pageNum.currentValue;
        }
        this.getPageList()
    }

    pageSizeChange(value) {
        this.storageService.set('pageSize', value);
        this.router.navigate(['../', 1, {timestamp: (new Date()).valueOf()}], {
            relativeTo: this.activatedRoute,
            queryParamsHandling: 'preserve',
            replaceUrl: true
        })
    }


    goTo() {
        if (this.pageChange.observers.length > 0) {
            this.getPageList();
            this.pageChange.emit(this.pageCurrent);
        } else {
            this.router.navigate(['../', this.pageCurrent], {
                relativeTo: this.activatedRoute,
                queryParamsHandling: 'preserve'
            })
        }
    }

    prevPage() {
        if (this.pageCurrent > 1) {
            this.pageCurrent -= 1;
            this.goTo();
        }
    }

    nextPage() {
        if (this.pageCurrent < this.pageTotal) {
            this.pageCurrent += 1;
            this.goTo();
        }
    }

    changePage(item) {
        if (item == '...') {
            return;
        } else {
            this.pageCurrent = item;
        }
        this.goTo();
    }

    private getPageList() {
        this.pageCurrent *= 1;
        let pageList = [];
        if (this.pageTotal <= this.pagesLength) {
            for (let i = 1; i <= this.pageTotal; i++) {
                pageList.push(i);
            }
        } else {
            let offset = (this.pagesLength - 1) / 2;
            if (this.pageCurrent <= offset) {
                // 左边没有...
                for (let i = 1; i <= offset + 1; i++) {
                    pageList.push(i);
                }
                pageList.push('...');
                pageList.push(this.pageTotal);
            } else if (this.pageCurrent > this.pageTotal - offset) {
                // 右边没有...
                pageList.push(1);
                pageList.push('...');
                for (let i = offset + 1; i >= 1; i--) {
                    pageList.push(this.pageTotal - i);
                }
                pageList.push(this.pageTotal);
            } else {
                // 两边都有...
                pageList.push(1);
                pageList.push('...');

                for (let i = Math.ceil(offset / 2); i >= 1; i--) {
                    pageList.push(this.pageCurrent - i);
                }
                pageList.push(this.pageCurrent);
                for (let i = 1; i <= offset / 2; i++) {
                    pageList.push(this.pageCurrent + i);
                }

                pageList.push('...');
                pageList.push(this.pageTotal);
            }
        }
        this.pageList = pageList;
    }
}