/*
Generate JSON Schema artifacts under __generated__/ and write index.ts re-exports.
*/

import { mkdirSync, writeFileSync } from "node:fs";
import { dirname, join, relative } from "node:path";
import { createGenerator } from "ts-json-schema-generator";
import { cleanStaleGenerated } from "./cleanup.ts";
import { discoverSchemaRoots, type SchemaRoot } from "./discover-schema-roots.ts";
import { GENERATED_DIR, schemaExportName, schemaJsonBasename, schemaJsonImportVar } from "./names.ts";

export interface RunSchemagenOptions {
  /** Project root (default: `process.cwd()`). */
  projectRoot?: string;
  /** Source tree directory relative to project root (default: `src`). Unused; kept for API compat. */
  srcDir?: string;
  /** Path to tsconfig relative to project root (default: `tsconfig.json`). */
  tsconfig?: string;
}

export interface RunSchemagenResult {
  schemas: number;
}

function resolveTsconfig(projectRoot: string, tsconfig: string): string {
  const path = join(projectRoot, tsconfig);
  try {
    return path;
  } catch {
    throw new Error(`tsconfig not found: ${path}`);
  }
}

function generatedDirForRoot(projectRoot: string, root: SchemaRoot): string {
  return join(dirname(join(projectRoot, root.path)), GENERATED_DIR);
}

function generateJson(projectRoot: string, tsconfigPath: string, root: SchemaRoot): Record<string, unknown> {
  const typeFile = join(projectRoot, root.sourcePath);
  const generator = createGenerator({
    path: typeFile,
    type: root.typeName,
    tsconfig: tsconfigPath,
    topRef: false,
    skipTypeCheck: false,
    jsDoc: "extended",
    additionalProperties: false,
  });
  const schema = generator.createSchema(root.typeName) as Record<string, unknown>;
  schema.additionalProperties = false;
  return schema;
}

function writeGeneratedIndex(generatedDir: string, roots: SchemaRoot[]): void {
  const sorted = [...roots].sort((left, right) => left.typeName.localeCompare(right.typeName));
  const lines = ["// Auto-generated by argsbarg schemagen — do not edit by hand.", ""];
  for (const root of sorted) {
    lines.push(`import ${schemaJsonImportVar(root.typeName)} from "./${schemaJsonBasename(root.typeName)}";`);
  }
  if (sorted.length > 0) {
    lines.push("");
  }
  for (const root of sorted) {
    lines.push(
      `export const ${schemaExportName(root.typeName)} = ${schemaJsonImportVar(root.typeName)} as Record<string, unknown>;`,
    );
    lines.push("");
  }
  writeFileSync(join(generatedDir, "index.ts"), `${lines.join("\n")}`);
}

/** Generate colocated `__generated__` JSON schemas and `index.ts` barrels. */
export function runSchemagen(options: RunSchemagenOptions = {}): RunSchemagenResult {
  const projectRoot = options.projectRoot ?? process.cwd();
  const srcDir = options.srcDir ?? "src";
  const tsconfigPath = resolveTsconfig(projectRoot, options.tsconfig ?? "tsconfig.json");

  const roots = discoverSchemaRoots(projectRoot, srcDir);
  const byGeneratedDir = new Map<string, SchemaRoot[]>();

  for (const root of roots) {
    const schema = generateJson(projectRoot, tsconfigPath, root);
    const generatedDir = generatedDirForRoot(projectRoot, root);
    mkdirSync(generatedDir, { recursive: true });
    const jsonPath = join(generatedDir, schemaJsonBasename(root.typeName));
    writeFileSync(jsonPath, `${JSON.stringify(schema, null, 2)}\n`);
    console.log(`wrote ${relative(projectRoot, jsonPath)} (${root.typeName})`);

    const list = byGeneratedDir.get(generatedDir) ?? [];
    list.push(root);
    byGeneratedDir.set(generatedDir, list);
  }

  for (const [generatedDir, dirRoots] of byGeneratedDir) {
    writeGeneratedIndex(generatedDir, dirRoots);
    console.log(`wrote ${relative(projectRoot, join(generatedDir, "index.ts"))}`);
  }

  cleanStaleGenerated(projectRoot, srcDir, byGeneratedDir);

  return { schemas: roots.length };
}