import {
    Inject,
    Injectable,
} from '@angular/core';

import {
    DOCUMENT,
} from '@angular/common';

@Injectable()
export class AutoNewLineService {
    public canvas: HTMLCanvasElement;
    private _lineSeparator = '\n';
    private _spaceCharacter = ' ';

    constructor(
        @Inject(DOCUMENT)
        private _document: Document,
    ) {}

    public getTextWidth(
        text: string,
        fontSize: string,
        fontFamily: string,
    ) {
        this.canvas = this.canvas ?
            this.canvas : this._document.createElement('canvas');
        const context = this.canvas.getContext('2d');
        const fontSizeAsShown = parseInt(fontSize, 10);
        context.font = (
            `${fontSizeAsShown}pt ${fontFamily}`
        );
        const metrics = context.measureText(text);
        return metrics.width;
    }

    public sortIntoLines(
        text: string,
        elementWidth: number,
        fontSize: string,
        fontFamily: string,
    ) {
        const lines = text.split(this._lineSeparator);
        const newLinesArray: string[] = [];
        let overflow = '';
        while (lines.length || overflow.length) {
            let lastChar = '';
            let line = lines.length > 0 ? lines.shift() : '';
            line = overflow + line;
            overflow = '';
            while (
                this.getTextWidth(
                    line, fontSize, fontFamily,
                ) > elementWidth
            ) {
                const lineSplit = line.split(this._spaceCharacter);
                if (lineSplit.length > 1) {
                    overflow = lineSplit.pop() +
                        this._spaceCharacter + overflow;
                    line = lineSplit.join(this._spaceCharacter);
                } else {
                    lastChar = line.charAt(line.length - 1);
                    line = line.substring(0, line.length - 1);
                    overflow = lastChar + overflow;
                }
            }
            newLinesArray.push(line);
        }
        return newLinesArray.join(this._lineSeparator).trim();
    }
}