From d040763a738fc522c68d888a277268da12a3d0b7 Mon Sep 17 00:00:00 2001
From: Ben Heidemann <ben@heidemann.co.uk>
Date: Sun, 4 Apr 2021 01:22:28 +0100
Subject: [PATCH] feat: add filer webpack plugin

---
 src/webpack-plugin/plugin.js     | 88 ++++++++++++++++++++++++++++++++
 src/webpack-plugin/processors.js | 33 ++++++++++++
 src/webpack-plugin/schema.js     | 26 ++++++++++
 src/webpack-plugin/utils.js      | 26 ++++++++++
 4 files changed, 173 insertions(+)
 create mode 100644 src/webpack-plugin/plugin.js
 create mode 100644 src/webpack-plugin/processors.js
 create mode 100644 src/webpack-plugin/schema.js
 create mode 100644 src/webpack-plugin/utils.js

diff --git a/src/webpack-plugin/plugin.js b/src/webpack-plugin/plugin.js
new file mode 100644
index 0000000..b1cb334
--- /dev/null
+++ b/src/webpack-plugin/plugin.js
@@ -0,0 +1,88 @@
+var path = require('path');
+var utils = require('./utils');
+
+const PLUGIN_NAME = 'filer-webpack-plugin';
+
+const OPTIONS_SCHEMA = require('./schema');
+const OPTIONS_PROCESSORS = require('./processors');
+
+module.exports = class FilerWebpackPlugin {
+
+    constructor(options = {}) {
+        utils.validateOptions(options, OPTIONS_SCHEMA);
+        this.options = utils.processOptions(options, OPTIONS_PROCESSORS);
+    }
+
+    apply(compiler) {
+        compiler.hooks.normalModuleFactory.tap(
+            PLUGIN_NAME,
+            (factory) => {
+                factory.hooks.resolve.tap(
+                    PLUGIN_NAME,
+                    (resolveData) => {
+                        // Resolve fsProvider if required
+                        if (
+                            resolveData.request === 'fsProvider'
+                            && resolveData.context === this.options.shimsDir
+                        ) {
+                            return this.resolveFsProvider(resolveData);
+                        }
+
+                        // Ignore filer files (these should resolve modules normally)
+                        if (resolveData.context.startsWith(this.options.filerDir)) return;
+
+                        // Apply fs, path and buffer shims if required
+                        switch (resolveData.request) {
+                            case 'fs':
+                                if (!this.options.shimFs) return;
+                                return this.applyFsShim(resolveData);
+                            case 'path':
+                                if (!this.options.shimPath) return;
+                                return this.applyPathShim(resolveData);
+                            case 'buffer':
+                                if (!this.options.shimBuffer) return;
+                                return this.applyBufferShim(resolveData);
+                            default:
+                                return;
+                        }
+                    }
+                );
+            },
+        )
+    }
+
+    resolveFsProvider(resolveData) {
+        switch (this.options.fsProvider) {
+            case 'default':
+                resolveData.request = path.join(this.options.fsProviderDir, 'default.js');
+                break;
+            case 'indexeddb':
+                resolveData.request = path.join(this.options.fsProviderDir, 'indexeddb.js');
+                break;
+            case 'memory':
+                resolveData.request = path.join(this.options.fsProviderDir, 'memory.js');
+                break;
+            case 'custom':
+                resolveData.request = path.join(this.options.fsProviderDir, 'custom.js');
+                break;
+            default:
+                throw new Error([
+                    `Invalid option for fsProvider.`,
+                    `fsProvider must be one of 'default', 'indexeddb', 'memory' or 'custom'.`,
+                    `If using a custom fsProvider, you must also provide the fsProviderDir option.`
+                ].join(' '));
+        }
+    }
+
+    applyFsShim(resolveData) {
+        resolveData.request = path.join(this.options.shimsDir, 'fs.js');
+    }
+    
+    applyPathShim(resolveData) {
+        resolveData.request = path.join(this.options.shimsDir, 'path.js');
+    }
+
+    applyBufferShim(resolveData) {
+        resolveData.request = path.join(this.options.shimsDir, 'buffer.js');
+    }
+}
diff --git a/src/webpack-plugin/processors.js b/src/webpack-plugin/processors.js
new file mode 100644
index 0000000..71f2a0e
--- /dev/null
+++ b/src/webpack-plugin/processors.js
@@ -0,0 +1,33 @@
+const ROOT_DIR_TAG = '<rootDir>';
+const CWD = process.cwd();
+
+module.exports = {
+    filerDir: {
+        process: function(value) {
+            if (!value) {
+                return path.join(CWD, 'node_modules', 'filer');
+            }
+            return value.replace(ROOT_DIR_TAG, CWD);
+        },
+    },
+    shimsDir: {
+        process: function(value) {
+            if (!value) {
+                return path.join(CWD, 'node_modules', 'filer', 'shims');
+            }
+            return value.replace(ROOT_DIR_TAG, CWD);
+        }
+    },
+    shimFs: { default: true },
+    shimPath: { default: true},
+    shimBuffer: { default: true},
+    fsProvider: { default: 'default'},
+    fsProviderDir: {
+        process: function(value) {
+            if (!value) {
+                return path.join(CWD, 'node_modules', 'filer', 'shims', 'providers');
+            }
+            return value.replace(ROOT_DIR_TAG, CWD);validateOptions
+        },
+    },
+};
diff --git a/src/webpack-plugin/schema.js b/src/webpack-plugin/schema.js
new file mode 100644
index 0000000..40e57ac
--- /dev/null
+++ b/src/webpack-plugin/schema.js
@@ -0,0 +1,26 @@
+module.exports = {
+    type: 'object',
+    properties: {
+        filerDir: {
+            type: 'string',
+        },
+        shimsDir: {
+            type: 'string',
+        },
+        shimFs: {
+            type: 'boolean',
+        },
+        shimPath: {
+            type: 'boolean',
+        },
+        shimBuffer: {
+            type: 'boolean',
+        },
+        fsProvider: {
+            type: 'string',
+        },
+        fsProviderDir: {
+            type: 'string',
+        },
+    }
+};
diff --git a/src/webpack-plugin/utils.js b/src/webpack-plugin/utils.js
new file mode 100644
index 0000000..79954cb
--- /dev/null
+++ b/src/webpack-plugin/utils.js
@@ -0,0 +1,26 @@
+var { validate } = require('schema-utils');
+
+function validateOptions(options, schema) {
+    validate(schema, options);
+}
+
+function processOptions(options, processors) {
+    const processedOptions = {};
+    
+    for (const [property, processor] of Object.entries(processors)) {
+        processedOptions[property] = options[property];
+        if (processedOptions[property] === undefined) {
+            processedOptions[property] = processor.default;
+        }
+        if (processor.process) {
+            processedOptions[property] = processor.process(processedOptions[property]);
+        }
+    }
+
+    return processedOptions;
+}
+
+module.exports = {
+    validateOptions,
+    processOptions,
+};