feat: add configuration file strategy

src/types/cli.types.ts

@@ -10,4 +10,27 @@ export interface CliOptions {
   dryRun?: boolean;
   selectEndpoints?: boolean;
   skipLint?: boolean;
+  config?: string;
+  initConfig?: string | boolean;
+}
+
+/**
+ * Per-tag configuration inside the generation config file.
+ */
+export interface TagConfig {
+  baseUrl: string;
+  endpoints: string[];
+}
+
+/**
+ * JSON configuration file schema.
+ * Allows full non-interactive control of the generation process.
+ */
+export interface GenerationConfig {
+  input: string;
+  output: string;
+  templates?: string;
+  skipInstall?: boolean;
+  skipLint?: boolean;
+  tags: Record<string, TagConfig>;
 }

src/utils/config.ts

@@ -0,0 +1,118 @@
+import fs from 'fs-extra';
+import { logInfo, logError } from './logger';
+import type { GenerationConfig, TagConfig } from '../types';
+import type { SwaggerAnalysis } from '../types';
+import type { TagSummary } from '../types';
+import type { ApiKeyInfo } from './environment-finder';
+
+/**
+ * Loads and validates a GenerationConfig from a JSON file.
+ */
+export function loadConfig(filePath: string): GenerationConfig {
+  if (!fs.existsSync(filePath)) {
+    logError(`Configuration file not found: ${filePath}`);
+    process.exit(1);
+  }
+
+  const raw = fs.readFileSync(filePath, 'utf8');
+  let config: GenerationConfig;
+
+  try {
+    config = JSON.parse(raw) as GenerationConfig;
+  } catch {
+    logError(`Invalid JSON in configuration file: ${filePath}`);
+    process.exit(1);
+  }
+
+  if (!config.tags || typeof config.tags !== 'object') {
+    logError('Configuration file must contain a "tags" object');
+    process.exit(1);
+  }
+
+  for (const [tag, tagConfig] of Object.entries(config.tags)) {
+    if (!tagConfig.baseUrl || typeof tagConfig.baseUrl !== 'string') {
+      logError(`Tag "${tag}" must have a "baseUrl" string`);
+      process.exit(1);
+    }
+    if (!Array.isArray(tagConfig.endpoints) || tagConfig.endpoints.length === 0) {
+      logError(`Tag "${tag}" must have a non-empty "endpoints" array`);
+      process.exit(1);
+    }
+  }
+
+  return config;
+}
+
+/**
+ * Builds a default GenerationConfig from a swagger analysis, including all tags
+ * and all endpoints. Useful for --init-config to scaffold a config template.
+ */
+export function generateDefaultConfig(
+  analysis: SwaggerAnalysis,
+  tagSummaries: TagSummary[],
+  cliOptions: {
+    input: string;
+    output: string;
+    templates?: string;
+    skipLint?: boolean;
+    skipInstall?: boolean;
+  },
+  apiKeys: ApiKeyInfo[]
+): GenerationConfig {
+  const tags: Record<string, TagConfig> = {};
+
+  for (const summary of tagSummaries) {
+    const matchingKey = apiKeys.find((k) =>
+      k.key.toLowerCase().includes(summary.tag.toLowerCase())
+    );
+
+    tags[summary.tag] = {
+      baseUrl: matchingKey?.key || 'apiUrl',
+      endpoints: summary.operations.map((op) => op.nickname)
+    };
+  }
+
+  const config: GenerationConfig = {
+    input: cliOptions.input,
+    output: cliOptions.output,
+    skipLint: cliOptions.skipLint ?? false,
+    skipInstall: cliOptions.skipInstall ?? false,
+    tags
+  };
+
+  if (cliOptions.templates) {
+    config.templates = cliOptions.templates;
+  }
+
+  return config;
+}
+
+/**
+ * Writes a GenerationConfig to a JSON file.
+ */
+export function writeConfig(config: GenerationConfig, filePath: string): void {
+  fs.writeFileSync(filePath, JSON.stringify(config, null, 2) + '\n', 'utf8');
+  logInfo(`Configuration file written to: ${filePath}`);
+}
+
+/**
+ * Derives the selectionFilter (tag → endpoint nicknames) from a GenerationConfig.
+ */
+export function deriveSelectionFilter(config: GenerationConfig): Record<string, string[]> {
+  const filter: Record<string, string[]> = {};
+  for (const [tag, tagConfig] of Object.entries(config.tags)) {
+    filter[tag] = [...tagConfig.endpoints];
+  }
+  return filter;
+}
+
+/**
+ * Derives the tagApiKeyMap (tag → baseUrl key) from a GenerationConfig.
+ */
+export function deriveTagApiKeyMap(config: GenerationConfig): Record<string, string> {
+  const map: Record<string, string> = {};
+  for (const [tag, tagConfig] of Object.entries(config.tags)) {
+    map[tag] = tagConfig.baseUrl;
+  }
+  return map;
+}