import { existsSync, readFileSync } from 'node:fs';
import { join, relative, resolve } from 'node:path';
import { walkFiles } from './file-rules.js';

const allowedSchemaVersions = new Set([1]);

const readJson = (path) => JSON.parse(readFileSync(path, 'utf8'));

export const validateSource = (sourceDir, config) => {
  const sourceRoot = resolve(sourceDir);
  const errors = [];
  const warnings = [];

  if (!allowedSchemaVersions.has(config.schemaVersion)) {
    errors.push(`Unsupported schemaVersion: ${config.schemaVersion}`);
  }

  if (config.type !== 'bridgeable-components') {
    errors.push(`Unsupported type: ${config.type}`);
  }

  for (const [key, path] of Object.entries(config.paths)) {
    if (!path || typeof path !== 'string') {
      errors.push(`paths.${key} must be a non-empty string.`);
      continue;
    }

    if (!existsSync(join(sourceRoot, path))) {
      warnings.push(`Configured path is missing: ${path}`);
    }
  }

  if (!existsSync(join(sourceRoot, config.entry.globalStyles))) {
    warnings.push(`Global style entry is missing: ${config.entry.globalStyles}`);
  }

  let specCount = 0;
  walkFiles(sourceRoot, (absolutePath) => {
    if (!absolutePath.endsWith('.component.json')) {
      return;
    }

    specCount += 1;
    const relativePath = relative(sourceRoot, absolutePath);
    let spec;

    try {
      spec = readJson(absolutePath);
    } catch (error) {
      errors.push(`Invalid JSON in ${relativePath}: ${error.message}`);
      return;
    }

    const expectedType = relativePath.startsWith(`${config.paths.components}/`)
      ? 'component'
      : 'section';

    if (spec.type && spec.type !== expectedType) {
      errors.push(`${relativePath} has type "${spec.type}" but expected "${expectedType}".`);
    }

    if (!spec.name || typeof spec.name !== 'string') {
      errors.push(`${relativePath} must define a string "name".`);
    }
  });

  if (specCount === 0) {
    warnings.push('No *.component.json files were found.');
  }

  return {
    valid: errors.length === 0,
    errors,
    warnings,
    specCount
  };
};