import path from 'path';

import { normalizeString } from '@vendure/common/lib/normalize-string';

import { AssetNamingStrategy } from './asset-naming-strategy';

/**
 * The default strategy normalizes the file names to remove unwanted characters and
 * in the case of conflicts, increments a counter suffix.
 */
export class DefaultAssetNamingStrategy implements AssetNamingStrategy {
    private readonly numberingRe = /__(\d+)\.[^.]+$/;

    generateSourceFileName(originalFileName: string, conflictFileName?: string): string {
        const normalized = normalizeString(originalFileName, '-');
        if (!conflictFileName) {
            return normalized;
        } else {
            return this.incrementOrdinalSuffix(normalized, conflictFileName);
        }
    }

    generatePreviewFileName(sourceFileName: string, conflictFileName?: string): string {
        const previewSuffix = '__preview';
        const previewFileName = this.isSupportedImageFormat(sourceFileName)
            ? this.addSuffix(sourceFileName, previewSuffix)
            : this.addSuffix(sourceFileName, previewSuffix) + '.png';

        if (!conflictFileName) {
            return previewFileName;
        } else {
            return this.incrementOrdinalSuffix(previewFileName, conflictFileName);
        }
    }

    /**
     * A "supported format" means that the Sharp library can transform it and output the same
     * file type. Unsupported images and other non-image files will be converted to png.
     *
     * See http://sharp.pixelplumbing.com/en/stable/api-output/#tobuffer
     */
    private isSupportedImageFormat(fileName: string): boolean {
        const imageExtensions = ['.jpg', '.jpeg', '.png', '.webp', '.tiff'];
        const ext = path.extname(fileName);
        return imageExtensions.includes(ext);
    }

    private incrementOrdinalSuffix(baseFileName: string, conflictFileName: string): string {
        const matches = conflictFileName.match(this.numberingRe);
        const ord = Number(matches && matches[1]) || 1;
        return this.addOrdinalSuffix(baseFileName, ord + 1);
    }

    private addOrdinalSuffix(fileName: string, order: number): string {
        const paddedOrder = order.toString(10).padStart(2, '0');
        return this.addSuffix(fileName, `__${paddedOrder}`);
    }

    private addSuffix(fileName: string, suffix: string): string {
        const ext = path.extname(fileName);
        const baseName = path.basename(fileName, ext);
        return `${baseName}${suffix}${ext}`;
    }
}
