breaking: CssWriter respects Rollup config (#136)

* break: emit CSS via `name` key;

- will respect Rollup's `output` naming conventions

* fix: respect `output.sourcemap` rollup configl

- do not emit sourcemap if Rollup told not to
- synchronize hashed output filename

* fix: respect `output.sourcemapExcludeSources` config

* fix: output minified sourcemap if not `dev` mode

* chore: update tests, removing forced assumptions

* chore: update & add tests

* chore: fix test dir paths

Author: lukeed

index.d.ts

@@ -1,26 +1,17 @@
-import { Plugin, RollupWarning } from 'rollup';
+import { Plugin, RollupWarning, SourceMap as Mapping } from 'rollup';
 import { PreprocessorGroup } from 'svelte/types/compiler/preprocess';
 import { CompileOptions } from 'svelte/types/compiler/interfaces';
 
-interface Css {
-  code: any;
-  map: any;
-}
+type SourceMap = Omit<Mapping, 'toString' | 'toUrl'>;
 
 declare class CssWriter {
   code: string;
   filename: string;
-  map: {
-    version: number;
-    file?: boolean;
-    sources: string[];
-    sourcesContent: string[];
-    names: any[];
-    mappings: string;
-  };
+  map: false | SourceMap;
   warn: RollupWarning;
-  emit(fileName: string, source: string): void;
-  write(dest: string, map?: boolean): void;
+  write(file: string, map?: boolean): void;
+  emit(name: string, source: string): string;
+  sourcemap(file: string, sourcemap: SourceMap): void;
   toString(): string;
 }
 
@@ -60,6 +51,12 @@ interface Options extends CompileOptions {
   //   }
   // },
 
+  /**
+   * Add extra code for development and debugging purposes.
+   * @default false
+   */
+  dev?: boolean;
+
   /**
    * Emit CSS as "files" for other plugins to process
    * @default false

index.js

@@ -70,34 +70,52 @@ function exists(file) {
 }
 
 class CssWriter {
-	constructor(code, filename, map, warn, toAsset) {
+	constructor(context, bundle, isDev, code, filename, map) {
 		this.code = code;
 		this.filename = filename;
-		this.emit = toAsset;
-		this.warn = warn;
-		this.map = {
+
+		this.map = map && {
 			version: 3,
 			file: null,
 			sources: map.sources,
 			sourcesContent: map.sourcesContent,
 			names: [],
 			mappings: map.mappings
 		};
+
+		this.warn = context.warn;
+		this.emit = (name, source) => context.emitFile({
+			type: 'asset', name, source
+		});
+
+		this.sourcemap = (file, mapping) => {
+			const ref = this.emit(file, this.code);
+			const filename = context.getFileName(ref);
+
+			const mapfile = `${filename}.map`;
+			const toRelative = src => path.relative(path.dirname(file), src);
+
+			if (bundle[filename]) {
+				bundle[filename].source += `\n/*# sourceMappingURL=${mapfile} */`;
+			} else {
+				// This should not ever happen, but just in case...
+				return this.warn(`Missing "${filename}" ("${file}") in bundle; skipping sourcemap!`);
+			}
+
+			const source = JSON.stringify({
+				...mapping,
+				file: filename,
+				sources: mapping.sources.map(toRelative),
+			}, null, isDev ? 2 : 0);
+
+			// use `fileName` to prevent additional Rollup hashing
+			context.emitFile({ type: 'asset', fileName: mapfile, source });
+		}
 	}
 
-	write(dest = this.filename, map = true) {
-		const basename = path.basename(dest);
-
-		if (map) {
-			this.emit(dest, `${this.code}\n/*# sourceMappingURL=${basename}.map */`);
-			this.emit(`${dest}.map`, JSON.stringify({
-				version: 3,
-				file: basename,
-				sources: this.map.sources.map(source => path.relative(path.dirname(dest), source)),
-				sourcesContent: this.map.sourcesContent,
-				names: [],
-				mappings: this.map.mappings
-			}, null, 2));
+	write(dest = this.filename, map = !!this.map) {
+		if (map && this.map) {
+			this.sourcemap(dest, this.map);
 		} else {
 			this.emit(dest, this.code);
 		}
@@ -299,32 +317,33 @@ module.exports = function svelte(options = {}) {
 		/**
 		 * If css: true then outputs a single file with all CSS bundled together
 		 */
-		generateBundle(options, bundle) {
+		generateBundle(config, bundle) {
 			if (css) {
 				// TODO would be nice if there was a more idiomatic way to do this in Rollup
 				let result = '';
 
 				const mappings = [];
-				const sources = [];
 				const sourcesContent = [];
+				const sources = [];
 
 				const chunks = Array.from(cssLookup.keys()).sort().map(key => cssLookup.get(key));
 
 				for (let chunk of chunks) {
 					if (!chunk.code) continue;
 					result += chunk.code + '\n';
 
-					if (chunk.map) {
-						const i = sources.length;
-						sources.push(chunk.map.sources[0]);
-						sourcesContent.push(chunk.map.sourcesContent[0]);
+
+					if (config.sourcemap && chunk.map) {
+						const len = sources.length;
+						config.sourcemapExcludeSources || sources.push(chunk.map.sources[0]);
+						config.sourcemapExcludeSources || sourcesContent.push(chunk.map.sourcesContent[0]);
 
 						const decoded = decode(chunk.map.mappings);
 
-						if (i > 0) {
+						if (len > 0) {
 							decoded.forEach(line => {
 								line.forEach(segment => {
-									segment[1] = i;
+									segment[1] = len;
 								});
 							});
 						}
@@ -335,12 +354,10 @@ module.exports = function svelte(options = {}) {
 
 				const filename = Object.keys(bundle)[0].split('.').shift() + '.css';
 
-				const writer = new CssWriter(result, filename, {
+				const writer = new CssWriter(this, bundle, !!options.dev, result, filename, config.sourcemap && {
 					sources,
 					sourcesContent,
 					mappings: encode(mappings)
-				}, this.warn, (fileName, source) => {
-					this.emitFile({ type: 'asset', fileName, source });
 				});
 
 				css(writer);